Chapter 22: A Hello, World!

Co-authored-by: godalming123 <68993177+godalming123@users.noreply.github.com>
Co-authored-by: Tamás Hadházy <85063808+Hels15@users.noreply.github.com>
Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: Symious <14933944+symious@users.noreply.github.com>
Co-authored-by: Jun Kawasaki <jun784@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

138 files changed, 2588 insertions, 954 deletions

diff --git a/src/main/java/com/seaofnodes/simple/Parser.java b/src/main/java/com/seaofnodes/simple/Parser.java
index 6f307785..ea618757 100644
--- a/src/main/java/com/seaofnodes/simple/Parser.java
+++ b/src/main/java/com/seaofnodes/simple/Parser.java
@@ -3,7 +3,7 @@ package com.seaofnodes.simple;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.*;
-import java.text.ParseException;
+
 import java.util.*;
 
 /**
@@ -23,7 +23,7 @@ public class Parser {
     public final CodeGen _code;
 
     // The Lexer.  Thin wrapper over a byte[] buffer with a cursor.
-    private final Lexer _lexer;
+    private Lexer _lexer;
 
     /**
      * Current ScopeNode - ScopeNodes change as we parse code, but at any point of time
@@ -83,7 +83,7 @@ public class Parser {
     // Mapping from a type name to a Type.  The string name matches
     // `type.str()` call.  No TypeMemPtrs are in here, because Simple does not
     // have C-style '*ptr' references.
-    public static HashMap<String, Type> TYPES;
+    public static HashMap<String, Type> TYPES = defaultTypes();
 
     // Mapping from a type name to the constructor for a Type.
     public final HashMap<String, StructNode> INITS;
@@ -91,7 +91,6 @@ public class Parser {
 
     public Parser(CodeGen code, TypeInteger arg) {
         _code = code;
-        _lexer = new Lexer(code._src);
         _scope = new ScopeNode();
         _continueScope = _breakScope = null;
         ZERO  = con(TypeInteger.ZERO).keep();
@@ -132,7 +131,9 @@ public class Parser {
     private <N extends Node> N ctrl(N n) { return _scope.ctrl(n); }
 
     public void parse() {
-        _xScopes.push(_scope);
+        // Graph callbacks during scope setup need a source position.
+        _lexer = new Lexer(com.seaofnodes.simple.sys.SYS);
+
         _scope.define(ScopeNode.CTRL, Type.CONTROL   , false, null, _lexer);
         _scope.define(ScopeNode.MEM0, TypeMem.BOT    , false, null, _lexer);
         _scope.define(ScopeNode.ARG0, TypeInteger.BOT, false, null, _lexer);
@@ -140,6 +141,16 @@ public class Parser {
         ctrl(XCTRL);
         _scope.mem(con(TypeMem.BOT));
 
+        // Parse the sys import
+        while( !_lexer.isEOF() ) {
+            parseStatement();
+            _lexer.skipWhiteSpace();
+        }
+
+        // Reset lexer for program text
+        _lexer = new Lexer(_code._src);
+        _xScopes.push(_scope);
+
         // Parse whole program, as-if function header "{ int arg -> body }"
         parseFunctionBody(_code._main,loc(),"arg");
 
@@ -148,9 +159,10 @@ public class Parser {
         // default main).
         FunNode main = _code.link(_code._main);
         StopNode stop = _code._stop;
-        if( main.ret().expr() instanceof ConstantNode && main.ret().mem().in(0)==main  && stop.nIns() > 1 ) {
+        if( main.ret().expr()._type==Type.TOP && main.uctrl()==null ) {
             // Kill an empty default main; so it does not attempt to put a
             // "main" in any final ELF file
+            main.setDef(1,XCTRL); // Delete default start input
             stop.delDef(stop._inputs.find(main.ret()));
         } else {
             // We have a non-empty default main.
@@ -188,7 +200,7 @@ public class Parser {
         ScopeNode breakScope = _breakScope; _breakScope = null;
         ScopeNode continueScope = _continueScope; _continueScope = null;
 
-        FunNode fun = _fun = (FunNode)peep(new FunNode(loc(),sig,null,_code._start));
+        FunNode fun = _fun = (FunNode)peep(new FunNode(loc(),sig,_nestedType,null,_code._start));
         // Once the function header is available, install in linker table -
         // allowing recursive functions.  Linker matches on declared args and
         // exact fidx, and ignores the return (because the fidx will only match
@@ -225,9 +237,14 @@ public class Parser {
         while (!peek('}') && !_lexer.isEOF())
             last = parseStatement();
 
-        // Last expression is the return
+        // Last expression is the return except for the top-level main
         if( ctrl()._type==Type.CONTROL )
-            fun.addReturn(ctrl(), _scope.mem(), last);
+            if( fun.sig() != _code._main )
+                fun.addReturn(ctrl(), _scope.mem(), last);
+            else {
+                fun.setDef(1,XCTRL); // Kill default main
+                _code.addAll(fun._outputs);
+            }
 
         // Pop off the inProgress node on the multi-exit Region merge
         assert r.inProgress();
@@ -285,8 +302,7 @@ public class Parser {
      * @return a {@link Node} or {@code null}
      */
     private Node parseStatement() {
-        if( false ) return null;
-        else if (matchx("return")  ) return parseReturn();
+        if(      matchx("return")  ) return parseReturn();
         else if (matchx("if")      ) return parseIf();
         else if (matchx("while")   ) return parseWhile();
         else if (matchx("for")     ) return parseFor();
@@ -400,7 +416,7 @@ public class Parser {
         // Our current scope is the body Scope
         ctrl(ifT.unkeep());     // set ctrl token to ifTrue projection
         _scope.addGuards(ifT,pred.unkeep(),false); // Up-cast predicate
-        parseStatement();       // Parse loop body
+        parseStatement().isKill();                 // Parse loop body
         _scope.removeGuards(ifT);
 
         // Merge the loop bottom into other continue statements
@@ -437,8 +453,11 @@ public class Parser {
 
         // At exit the false control is the current control, and
         // the scope is the exit scope after the exit test.
-        _xScopes.pop();
-        _xScopes.push(exit);
+        // During sys parsing, there is no xscope here.
+        if( !_xScopes.isEmpty() ) {
+            _xScopes.pop();
+            _xScopes.push( exit );
+        }
         _scope = exit;
         return ZERO;
     }
@@ -622,7 +641,7 @@ public class Parser {
             throw error("Cannot reassign final '"+name+"'");
 
         // Lift expression, based on type
-        Node lift = liftExpr(expr.keep(), def.type());
+        Node lift = liftExpr(expr.keep(), def.type(), true);
         // Update
         _scope.update(name,lift);
         // Return un-lifted expr
@@ -631,19 +650,30 @@ public class Parser {
 
     // Apply declared access permissions; widen floats and narrow integers.
     // Early error if types do not match variable.
-    private Node liftExpr( Node expr, Type t ) {
-        assert !(expr._type instanceof TypeMemPtr tmp) || !tmp.isFRef();
+    private Node liftExpr( Node expr, Type t, boolean isLoad ) {
+        if( expr._type instanceof TypeMemPtr tmp && tmp.isFRef() )
+            throw error("Must define forward ref "+tmp._obj._name);
         // Read-only access is deep; a fixed binding alone does not remove access.
         if( t instanceof TypeMemPtr tmp && tmp.isFinal() ) {
             expr = peep(new ReadOnlyNode(expr));
         }
+        // Auto-widen array to i64 (cast ptr to raw int bits)
+        if( t == TypeInteger.BOT && expr._type instanceof TypeMemPtr tmp && tmp._obj.isAry() )
+            expr = peep(new AddNode(peep(new CastNode(t,ctrl(),expr)),con(tmp._obj.aryBase())));
         // Auto-widen int to float
         expr = widenInt( expr, t );
-        // Auto-narrow wide ints to narrow ints
-        expr = zsMask(expr,t);
+        // Auto-narrow wide ints to narrow ints.  For loads, emit code to force
+        // the loaded value to match the declared sign/zero bits.  For stores,
+        // just force the type, acting "as if" the store silently truncates.
+        if( expr._type instanceof TypeFloat && t instanceof TypeInteger )
+            expr = peep(new ToIntegerNode(expr));
+        Type et = expr._type;
+        if( isLoad ) { expr = zsMask(expr,t); et = expr._type; }
+        else if( et instanceof TypeInteger && t instanceof TypeInteger ) et=t;
+
         // Type is sane
-        if( expr._type!=Type.BOTTOM && (!expr._type.shallowISA(t) || !expr._type.accessISA(t)) )
-            throw error("Type " + expr._type.str() + " is not of declared type " + t.str());
+        if( et!=Type.BOTTOM && (!et.shallowISA(t) || !et.accessISA(t)) )
+            throw error("Type " + et.str() + " is not of declared type " + t.str());
         return expr;
     }
 
@@ -659,7 +689,10 @@ public class Parser {
      * exprAsgn = var '=' exprAsgn | expr
      */
     private Node parseDeclarationStatement() {
+        int old = pos();
         Type t = type();
+        if( peek('.') )         // Ambiguity static vars: "type.var", parse as expression
+            { pos(old); t=null; }
         if( t == null )
             return require(parseAsgn(),";");
 
@@ -676,9 +709,9 @@ public class Parser {
         if( t instanceof TypeMemPtr tmp ) {
             Type base = TYPES.get(tmp._obj._name);
             TypeMemPtr ptr = (TypeMemPtr)base;
-            return (tmp._ro ? ptr.makeRO() : ptr).makeNullable();
+            return ptr.withAccess(tmp._ro).makeNullable();
         }
-        return t.glb();
+        return t.glb(false);
     }
 
     // The binding modifier sits immediately before the name. It never
@@ -701,7 +734,9 @@ public class Parser {
         // Optional initializing expression follows
         Node expr;
         if( match("=") ) {
-            expr = parseAsgn();
+            expr = isExternDecl()
+                ? externDecl(name,t)
+                : parseAsgn();
             // var/val, then type comes from expression
             if( inferType ) {
                 if( expr._type==Type.NIL )
@@ -709,14 +744,17 @@ public class Parser {
                 t = expr._type;
                 if( !xfinal ) t = inferredType(t);  // Widen if not final
             }
-            if( t instanceof TypeFunPtr && expr._type instanceof TypeFunPtr tfp && tfp.isConstant() )
-                _code.link(tfp)._name = name;
+            // expr is a constant function
+            if( t instanceof TypeFunPtr && expr._type instanceof TypeFunPtr tfp && tfp.isConstant() ) {
+                if( expr instanceof ExternNode ) t = expr._type; // Upgrade declared type to exact function
+                else _code.link(tfp).setName(name); // Assign debug name to Simple function
+            }
 
         } else {
             // Need an expression to infer the type.
             // Also, if not-null then need an initializing expression.
             // Allowed in a class def, because type/init will happen in the constructor.
-            if( (inferType || (t instanceof TypeNil tn && !tn.nullable() )) && !_scope.inCon() )
+            if( (inferType || (t instanceof TypeNil tn && !tn.nullable() )) && !_scope.inConstructor() )
                 throw errorSyntax("=expression");
             // Initial value for uninitialized struct fields.
             expr = switch( t ) {
@@ -732,7 +770,7 @@ public class Parser {
         }
 
         // Lift expression, based on type
-        Node lift = liftExpr(expr, t);
+        Node lift = liftExpr(expr, t, true);
 
         // Lift type to the declaration.  This will report as an error later if
         // we cannot lift the type.
@@ -748,23 +786,23 @@ public class Parser {
 
     /**
      * Parse a struct declaration, and return the following statement.
-     * Only allowed in top level scope.
-     * Structs cannot be redefined.
+     * Structs cannot be redefined, but can be nested.
      *
-     * @return The statement following the struct
+     * @return zero
      */
+    private String _nestedType;
     private Node parseStruct() {
-        if (_xScopes.size() > 1) throw error("struct declarations can only appear in top level scope");
+        // "struct" already parsed, so expect the struct name next.
+        String old = _nestedType;
         String typeName = requireId();
-        Type t = TYPES.get(typeName);
-        if( t!=null && !(t instanceof TypeMemPtr tmp && tmp.isFRef() ) )
-            throw error("struct '" + typeName + "' cannot be redefined");
+        if( old!=null ) typeName = old+"."+typeName;
+        _nestedType = typeName;
 
         // A Block scope parse, and inspect the scope afterward for fields.
         _scope.push(ScopeNode.Kind.Constructor);
         require("{");
         while (!peek('}') && !_lexer.isEOF())
-            parseStatement();
+            parseStatement().isKill();
 
         // Grab the declarations and build fields and a Struct
         int lexlen = _scope._lexSize.last();
@@ -772,15 +810,19 @@ public class Parser {
         StructNode s = new StructNode();
         Ary<Field> fs = new Ary<>(Field.class);
         for( int i=lexlen; i<varlen; i++ ) {
-            s.addDef(_scope.in(i));
-            Var v = _scope._vars.at(i);
-            if( !v.isFRef() )  // Promote to outer scope, not defined here
-                fs.push(Field.make(v._name,v.type(),_code.getALIAS(),v._final));
+            Var v = _scope.var(i);
+            if( v.isFRef() )  continue; // Promote to outer scope, not defined here
+            s.addDef(_scope.in(i)); // Keep the program code to generate instance
+            fs.push(Field.make(v._name,v.type(),_code.getALIAS(),v._final));
         }
+        // Save instance default constructor
         TypeStruct ts = s._ts = TypeStruct.make(typeName, fs.asAry());
+        s.setType(s.compute()); // Do not call peephole, in case the entire struct is a big plain constant
         TYPES.put(typeName, TypeMemPtr.make(ts));
-        INITS.put(typeName,s.peephole().keep());
+        INITS.put(typeName,s.keep());
+
         // Done with struct/block scope
+        _nestedType = old;
         require("}");
         require(";");
         _scope.pop();
@@ -811,6 +853,20 @@ public class Parser {
         if( t0 == null && KEYWORDS.contains(tname) )
             return posT(old1);
         if( t0 == Type.BOTTOM || t0 == Type.TOP ) return t0; // var/val type inference
+
+        // Check for subtype.
+        while( true ) {
+            int old2 = pos();
+            if( !match(".") )  break;
+            String sname = _lexer.matchId();
+            if( sname==null ) { pos(old2); break; }
+            String tsname = tname+"."+sname;
+            t0 = TYPES.get(tsname);
+            if( t0==null ) { pos(old2); t0 = TYPES.get(tname); break; }
+            tname = tsname;
+        }
+
+        // Still no type found?  Assume forward reference
         Type t1 = t0 == null ? TypeMemPtr.make(TypeStruct.makeFRef(tname)) :t0; // Null: assume a forward ref type
         // A qualifier before the name applies to the struct reference, not
         // to an enclosing array. Arrays have their own [] / [~] qualifier.
@@ -843,13 +899,12 @@ public class Parser {
         int old2 = pos();
         if( !match("!") ) match("~");
         String id = _lexer.matchId();
-        if( !(peek(',') || peek(';') || match("->")) )
-            return posT(old1);
-        pos(old2);              // Reset lexer to reparse
-        if( id==null )
+        if( !(peek(',') || peek(';') || match("->")) || id==null )
             return posT(old1);  // Reset lexer to reparse
+        pos(old2);              // Reset lexer to reparse
         // Yes a forward ref, so declare it
         TYPES.put(tname,((TypeMemPtr)t1).withAccess(false));
+        // Return the (array, final) type
         return t2;
     }
 
@@ -866,10 +921,9 @@ public class Parser {
             if( t instanceof TypeMemPtr ptr && (ptr._obj._fields==null || !ptr._obj.isAry()) &&
                 ary._fields[1]._type instanceof TypeMemPtr old )
                 t = old.withAccess(ptr._ro);
-            return TypeMemPtr.make(TypeStruct.makeAry(TypeInteger.U32,ary._fields[0]._alias,t,ary._fields[1]._alias));
+            return TypeMemPtr.make(TypeStruct.makeAry(tname,TypeInteger.U32,ary._fields[0]._alias,t,ary._fields[1]._alias));
         }
-        // Need make an array type.
-        TypeStruct ts = TypeStruct.makeAry(TypeInteger.U32,_code.getALIAS(),t,_code.getALIAS());
+        TypeStruct ts = TypeStruct.makeAry(tname,TypeInteger.U32,_code.getALIAS(),t,_code.getALIAS());
         assert ts.str().equals(tname);
         TypeMemPtr tary = TypeMemPtr.make(ts);
         TYPES.put(tname,tary);
@@ -1083,12 +1137,28 @@ public class Parser {
      */
     private Node parsePrimary() {
         if( _lexer.isNumber(_lexer.peek()) ) return parseLiteral();
+        if( _lexer.peek('"') ) return newString(parseString());
         if( matchx("true" ) ) return con(1);
         if( matchx("false") ) return ZERO;
         if( matchx("null" ) ) return NIL;
+        if( match ("'"    ) ) return parseChar();
         if( match ("("    ) ) return require(parseAsgn(), ")");
         if( matchx("new"  ) ) return alloc();
         if( match ("{"    ) ) return require(func(),"}");
+
+        // Parse static variable lookup: `type.fld` in the type namespace
+        Type t = type();
+        if( t!=null && match(".") ) {
+            String fld = requireId();
+            TypeMemPtr tmp = ((TypeMemPtr)t);
+            String tname = tmp._obj._name;
+            StructNode init = INITS.get(tname);
+            int idx = tmp._obj.find(fld);
+            if( idx == -1 )
+                throw error("Accessing unknown STATIC field");
+            return init.in(idx);
+        }
+
         // Expect an identifier now
         Var n = requireLookupId();
         Node rvalue = _scope.in(n);
@@ -1137,12 +1207,13 @@ public class Parser {
         };
         // Convert to float ops, or narrow int types; error if not declared type.
         // Also, if postfix LHS is still keep()
-        return liftExpr(peep(op.widen()),t);
+        return liftExpr(peep(op.widen()),t,true);
     }
 
 
     // Expect an ID here.  If not found, assume a forward reference function
     Var requireLookupId() {
+        // Try in the normal variable namespace
         String id = _lexer.matchId();
         if( id == null || KEYWORDS.contains(id) )
             throw errorSyntax("an identifier or expression");
@@ -1261,6 +1332,18 @@ public class Parser {
         ALTMP.clear();  ALTMP.add(len.unkeep()); ALTMP.add(con(ary._fields[1]._type.makeZero()));
         return newStruct(ary,size,0,ALTMP);
     }
+    private Node newString(String s) {
+        TypeMemPtr tmp = typeAry(TypeInteger.U8);
+        int  lenAlias = tmp._obj.field("#" )._alias;
+        int elemAlias = tmp._obj.field("[]")._alias;
+        TypeConAryB con = TypeConAryB.make(s);
+        Type elem = con.elem();
+        // Make a TMP, not-null (byte)2, singleton (true) (requires text
+        // strings are hash-interned), with a TypeStruct having a constant
+        // array body.
+        TypeMemPtr str = TypeMemPtr.make((byte)2,TypeStruct.makeAry("[u8]", TypeInteger.U32, lenAlias, elem, elemAlias, true, con),true);
+        return con(str.makeRO());
+    }
 
     // Memory is one hidden SSA variable, including across branches and loops.
     private Node mem() { return _scope.mem(); }
@@ -1301,14 +1384,12 @@ public class Parser {
             throw error("Accessing unknown field '" + name + "' from 'null'");
 
         // Sanity check expr for being a reference
-        if( !(expr._type instanceof TypeMemPtr ptr) ) {
+        if( !(expr._type instanceof TypeMemPtr ptr) )
             throw error( "Expected "+(name=="#" || name=="[]" ? "array" : "reference")+" but found " + expr._type.str() );
-        }
 
-        // Sanity check field name for existing
-        TypeMemPtr tmp = (TypeMemPtr)TYPES.get(ptr._obj._name);
-        if( tmp == null ) throw error("Accessing unknown field '" + name + "' from '" + ptr + "'");
-        TypeStruct base = ptr._obj.isAry() ? ptr._obj : tmp._obj;
+        // Find the field from the Type.  Lookup in the base object field names.
+        TypeStruct base = ptr._obj;
+        assert !base.isFRef();
         int fidx = base.find(name);
         if( fidx == -1 ) throw error("Accessing unknown field '" + name + "' from '" + ptr.str() + "'");
 
@@ -1329,7 +1410,7 @@ public class Parser {
         // Disambiguate "obj.fld==x" boolean test from "obj.fld=x" field assignment
         if( matchOpx('=','=') ) {
             Node val = parseAsgn().keep();
-            Node lift = liftExpr( val, tf );
+            Node lift = liftExpr( val, tf, false );
 
             store(name,f._alias,tf,expr.unkeep(),off.unkeep(),lift,false,base.isAry() ? ctrl() : null);
             return val.unkeep();        // "obj.a = expr" returns the expression while updating memory
@@ -1404,7 +1485,7 @@ public class Parser {
         // Make a concrete function type, with a fidx
         TypeFunPtr tfp = _code.makeFun(TypeTuple.make(ts.asAry()),Type.BOTTOM);
         ReturnNode ret = parseFunctionBody(tfp,loc,finals,ids.asAry());
-        return con(ret._fun.sig());
+        return new FunPtrNode(ret._fun.sig(),ret).peephole();
     }
 
     /**
@@ -1417,10 +1498,10 @@ public class Parser {
         if( expr._type == Type.NIL )
             throw error("Calling a null function pointer");
         if( !(expr instanceof FRefNode) && !expr._type.isa(TypeFunPtr.BOT) )
-            throw error("Expected a function but got "+expr._type.glb().str());
+            throw error("Expected a function but got "+expr._type.glb(false).str());
         expr.keep();            // Keep while parsing args
 
-        Ary<Node> args = new Ary<Node>(Node.class);
+        Ary<Node> args = new Ary<>( Node.class );
         args.push(null);        // Space for ctrl,mem
         args.push(null);
         while( !peek(')') ) {
@@ -1458,6 +1539,21 @@ public class Parser {
         return new ProjNode(cend,2,"#2").peephole();
     }
 
+    // Just after parsing "type foo = " can parse `"C"`
+    private boolean isExternDecl( ) {
+        int old = pos();
+        String s = parseString();
+        if( "C".equals(s) ) return true;
+        pos(old);
+        return false;
+    }
+    // External linked constant
+    private Node externDecl( String ex, Type t ) {
+        if( t instanceof TypeFunPtr tfp )          // Generic TFP from type parse
+            t  = _code.makeFun(tfp._sig,tfp._ret); // Get a FIDX, becomes a constant
+        return new ExternNode(t,ex).peephole();
+    }
+
     /**
      * Parse integer literal
      *
@@ -1474,6 +1570,50 @@ public class Parser {
         return _scope.upcastGuard(n.peephole());
     }
 
+    // Parse a string or null
+    private String parseString() {
+        if( !peek('"') ) return null;
+        _lexer.inc();
+        StringBuilder sb = new StringBuilder();
+        while( !_lexer.isEOF() ) {
+            char c = _lexer.nextChar();
+            if( c=='"' ) return sb.toString();
+            if( c!='\\' ) {
+                sb.append(c);
+                continue;
+            }
+            if( _lexer.isEOF() )
+                throw error("Unclosed string");
+            sb.append(escapedChar("string"));
+        }
+        throw error("Unclosed string");
+    }
+
+    private char escapedChar(String kind) {
+        char esc = _lexer.nextChar();
+        return switch( esc ) {
+        case '0'  -> '\u0000';
+        case 'n'  -> '\n';
+        case 't'  -> '\t';
+        case 'r'  -> '\r';
+        case '\\' -> '\\';
+        case '"'  -> '"';
+        case '\'' -> '\'';
+        default -> throw error("Unknown "+kind+" escape \\\\"+esc);
+        };
+    }
+
+    // Already parsed "'"
+    private Node parseChar() {
+        if( _lexer.isEOF() ) throw error("Unclosed character");
+        char c = _lexer.nextChar();
+        if( c=='\\' ) {
+            if( _lexer.isEOF() ) throw error("Unclosed character");
+            c = escapedChar("character");
+        }
+        return require(con(TypeInteger.constant(c)),"'");
+    }
+
     //////////////////////////////////
     // Utilities for lexical analysis
 
@@ -1617,7 +1757,15 @@ public class Parser {
                          _input[_position  ] == '/' &&
                          _input[_position+1] == '/') {
                     inc(); inc();
-                    while( !isEOF() && _input[_position] != '\n' ) inc();
+                    while( !isEOF() && _input[_position] != '\n' )
+                        inc();
+                } else if( _position+2 < _input.length &&
+                         _input[_position  ] == '/' &&
+                         _input[_position+1] == '*') {
+                    // Skip /*comment*/
+                    while( !isEOF() && !(_input[_position-1] == '*' && _input[_position] == '/'))
+                        inc();
+                    inc();
                 } else break;
             }
         }
diff --git a/src/main/java/com/seaofnodes/simple/Var.java b/src/main/java/com/seaofnodes/simple/Var.java
index 6e621875..14295395 100644
--- a/src/main/java/com/seaofnodes/simple/Var.java
+++ b/src/main/java/com/seaofnodes/simple/Var.java
@@ -9,11 +9,13 @@ import com.seaofnodes.simple.type.*;
 public class Var {
 
     public final String _name;   // Declared name
+    // These fields are not final for forward reference late updates or
+    // promotions.
     public int _idx;             // index in containing scope
     private Type _type;          // Declared type
     public boolean _final;       // Final field
-    public Parser.Lexer _loc;    // Source location
     public boolean _fref;        // Forward ref
+    public Parser.Lexer _loc;    // Source location
 
     public Var(int idx, String name, Type type, boolean xfinal, Parser.Lexer loc ) {
         this(idx,name,type,xfinal,loc,false);
@@ -23,8 +25,8 @@ public class Var {
         _name = name;
         _type = type;
         _final = xfinal;
-        _loc = loc;
         _fref = fref;
+        _loc = loc;
     }
     // Raw declared type, without resolving a forward reference while printing.
     public Type _type() { return _type; }
@@ -34,10 +36,6 @@ public class Var {
         Type def = Parser.TYPES.get(((TypeMemPtr)_type)._obj._name);
         return (_type=_type.meet(def));
     }
-    public Type lazyGLB() {
-        Type t = type();
-        return t instanceof TypeMemPtr ? t : t.glb();
-    }
 
     // Forward reference variables (not types) must be BOTTOM and
     // distinct from inferred variables
@@ -47,8 +45,8 @@ public class Var {
         assert isFRef() && xfinal;
         _type = type;
         _final = true;
-        _loc = loc;
         _fref = false;
+        _loc = loc;
     }
 
     @Override public String toString() {
diff --git a/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java b/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
index 2c44cb05..8a3d6322 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
@@ -24,7 +24,7 @@ public class CodeGen {
         Opto,                   // Run ideal optimizations
         TypeCheck,              // Last check for bad programs
         LoopTree,               // Build a loop tree; break infinite loops
-        InstSelect,             // Convert to target hardware nodes
+        Select,                 // Convert to target hardware nodes
         Schedule,               // Global schedule (code motion) nodes
         LocalSched,             // Local schedule
         RegAlloc,               // Register allocation
@@ -38,6 +38,7 @@ public class CodeGen {
     public final String _src;
     // Compile-time known initial argument type
     public final TypeInteger _arg;
+
     // ---------------------------
     public CodeGen( String src ) { this(src, TypeInteger.BOT, 123L ); }
     public CodeGen( String src, TypeInteger arg, long workListSeed ) {
@@ -57,14 +58,15 @@ public class CodeGen {
     public CodeGen driver( Phase phase ) { return driver(phase,null,null); }
     public CodeGen driver( Phase phase, String cpu, String callingConv ) {
         if( _phase==null )                       parse();
-        if( _phase.ordinal() < phase.ordinal() ) opto();
-        if( _phase.ordinal() < phase.ordinal() ) typeCheck();
-        if( _phase.ordinal() < phase.ordinal() ) loopTree();
-        if( _phase.ordinal() < phase.ordinal() && cpu != null ) instSelect(cpu,callingConv);
-        if( _phase.ordinal() < phase.ordinal() ) GCM();
-        if( _phase.ordinal() < phase.ordinal() ) localSched();
-        if( _phase.ordinal() < phase.ordinal() ) regAlloc();
-        if( _phase.ordinal() < phase.ordinal() ) encode();
+        int p1 = phase.ordinal();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.Opto      .ordinal() ) opto();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.TypeCheck .ordinal() ) typeCheck();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.LoopTree  .ordinal() ) loopTree();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.Select    .ordinal() && cpu != null ) instSelect(cpu,callingConv);
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.Schedule  .ordinal() ) GCM();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.LocalSched.ordinal() ) localSched();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.RegAlloc  .ordinal() ) regAlloc();
+        if( _phase.ordinal() < p1 && _phase.ordinal() < Phase.Encoding  .ordinal() ) encode();
         return this;
     }
 
@@ -121,7 +123,7 @@ public class CodeGen {
         return TypeFunPtr.make((byte)2,sig,ret, 1L<<fidx );
     }
     // Signature for MAIN
-    public TypeFunPtr _main = makeFun(TypeTuple.MAIN,Type.BOTTOM);
+    public final TypeFunPtr _main = makeFun(TypeTuple.MAIN,Type.BOTTOM);
     // Reverse from a constant function pointer to the IR function being called
     public FunNode link( TypeFunPtr tfp ) {
         assert tfp.isConstant();
@@ -176,6 +178,25 @@ public class CodeGen {
 
         // Pessimistic peephole optimization on a worklist
         _iter.iterate(this);
+
+        // Not really a true optimistic pass, but look for unlinked functions.
+        // This can be removed, which may trigger another round of pessimistic.
+        // This is the point where we flip from a virtual Call Graph (any call
+        // can call any function) to having a correct (but conservative) CG.
+
+        FunNode main = link(_main);
+        for( int i=0; i<_start.nOuts(); i++ ) {
+            Node use = _start.out(i);
+            if( use instanceof FunNode fun &&
+                fun.nIns()==2 && fun.in(1)==_start && fun != main && !fun.hasPtr() &&
+                    (fun._name==null || fun._name.startsWith("sys.")) ) {
+                add(fun).setDef(1,Parser.XCTRL);
+                addAll(fun._outputs);
+                i--;
+            }
+        }
+        _iter.iterate(this);
+
         _tOpto = (int)(System.currentTimeMillis() - t0);
 
         // TODO:
@@ -219,7 +240,7 @@ public class CodeGen {
         _phase = Phase.LoopTree;
         long t0 = System.currentTimeMillis();
         // Build the loop tree, fix never-exit loops
-        _start.buildLoopTree(_stop);
+        _start.buildLoopTree(_start,_stop);
         _tLoopTree = (int)(System.currentTimeMillis() - t0);
         return this;
     }
@@ -247,7 +268,7 @@ public class CodeGen {
     public CodeGen instSelect( String cpu, String callingConv ) { return instSelect(cpu,callingConv,PORTS); }
     public CodeGen instSelect( String cpu, String callingConv, String base ) {
         assert _phase.ordinal() == Phase.LoopTree.ordinal();
-        _phase = Phase.InstSelect;
+        _phase = Phase.Select;
 
         _callingConv = callingConv;
 
@@ -278,14 +299,14 @@ public class CodeGen {
         _rpcMask = new RegMask(_mach.rpc());
         _retMasks[3] = _rpcMask;
 
-
         // Convert to machine ops
         long t0 = System.currentTimeMillis();
         _uid = 1;               // All new machine nodes reset numbering
         var map = new IdentityHashMap<Node,Node>();
         _instSelect( _stop, map );
         _stop  = ( StopNode)map.get(_stop );
-        _start = (StartNode)map.get(_start);
+        StartNode start = (StartNode)map.get(_start);
+        _start = start==null ? new StartNode(_start) : start;
         _instOuts(_stop,visit());
         _visit.clear();
         _tInsSel = (int)(System.currentTimeMillis() - t0);
@@ -310,14 +331,14 @@ public class CodeGen {
 
         // Produce a machine node from n; map it to flag as done so stops cycles.
         map.put(n, x=_mach.instSelect(n) );
+        // Stop retains the callable body. Its lifetime edge is not a machine operand.
+        if( n instanceof FunPtrNode ) x._inputs.pop();
         // Walk machine op and replace inputs with mapped inputs
         for( int i=0; i < x.nIns(); i++ )
             x._inputs.set(i, _instSelect(x.in(i),map) );
         if( x instanceof MachNode mach )
             mach.postSelect(this);  // Post selection action
 
-        // Updates forward edges only.
-        n._outputs.clear();
         return x;
     }
 
@@ -340,7 +361,7 @@ public class CodeGen {
 
     // Global schedule (code motion) nodes
     public CodeGen GCM() {
-        assert _phase.ordinal() <= Phase.InstSelect.ordinal();
+        assert _phase.ordinal() <= Phase.Select.ordinal();
         _phase = Phase.Schedule;
         long t0 = System.currentTimeMillis();
 
@@ -439,8 +460,10 @@ public class CodeGen {
     String printCFG() {
         if( _cfg==null ) return "no CFG";
         SB sb = new SB();
-        for( CFGNode cfg : _cfg )
-            IRPrinter.printLine(cfg,sb);
+        for( CFGNode cfg : _cfg ) {
+            sb.fix(8,""+(int)cfg._idepth);
+            IRPrinter.printLine( cfg, sb );
+        }
         return sb.toString();
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java b/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java
index d1d20919..88af3f27 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/ElfFile.java
@@ -274,8 +274,6 @@ public class ElfFile {
         int start_global = num+1; // Add one to skip the final .rela.text local symbol
         for( Symbol a: symbols._symbols )
             a._index = start_global++;
-        int bigConIdx = start_global;
-        start_global += enc._bigCons.size();
 
         // create .text relocations
         DataSection text_rela = new DataSection(".rela.text", 4 /* SHT_RELA */);
@@ -299,10 +297,10 @@ public class ElfFile {
 
         // Write relocations for the constant pool
         for( Encoding.Relo relo : enc._bigCons.values() ) {
-            Symbol glob = new Symbol("GLOB$"+bigConIdx, rdata._index, SYM_BIND_GLOBAL, SYM_TYPE_FUNC);
+            Symbol glob = new Symbol("CPOOL$"+start_global, rdata._index, SYM_BIND_GLOBAL, SYM_TYPE_FUNC);
             glob._value = relo._target;
-            glob._size = 1 << relo._t.log_size();
-            glob._index = bigConIdx++;
+            glob._size = relo._t.size();
+            glob._index = start_global++;
             symbols.push(glob);
             write8(text_rela._contents, relo._opStart+relo._off);
             write8(text_rela._contents, ((long)glob._index << 32L) | relo._elf );
@@ -314,6 +312,7 @@ public class ElfFile {
         text_rela._info = text._index;
         pushSection(text_rela);
 
+        // Final .rela.text symbol
         Symbol sym = new Symbol(text_rela._name, num++, SYM_BIND_LOCAL, SYM_TYPE_SECTION);
         sym._name_pos = text_rela._name_pos;
         sym._size = text_rela.size();
diff --git a/src/main/java/com/seaofnodes/simple/codegen/Encoding.java b/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
index 81f195b1..aad19090 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
@@ -50,13 +50,15 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
         public final Node _op;
         public final Type _t;          // Constant type
         public final int _align;       // Log alignment, captured for diagnostic display
+        public final int _structSize;  // Capture layout during encoding, not printing
         public final byte _off;        // Offset from start of opcode
         public final byte _elf;        // ELF relocation type, e.g. 2/PC32
-        public int _target;      // Where constant is finally placede
+        public int _target;      // Where constant is finally placed
         public int _opStart;     // Opcode start
         Relo( Node op, Type t, byte off, byte elf ) {
             _op=op;  _t=t;  _off=off; _elf=elf;
-            _align = t.log_size();
+            _align = t.alignment();
+            _structSize = t instanceof TypeStruct ts ? ts.size() : 0;
         }
     }
     public final HashMap<Node,Relo> _bigCons = new HashMap<>();
@@ -142,8 +144,8 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
 
 
     final HashMap<Node,String> _externals = new HashMap<>();
-    public Encoding external( Node call, String extern ) {
-        _externals.put(call,extern);
+    public Encoding external( Node n, String extern ) {
+        _externals.put(n,extern);
         return this;
     }
 
@@ -187,12 +189,10 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
         Ary<CFGNode> rpo = new Ary<>(CFGNode.class);
         rpos.put(_code._start.loop(),rpo);
         BitSet visit = _code.visit();
-        //IdentityHashMap<CFGNode,LoopNode> looptail = new IdentityHashMap<>();
         rpo.add(_code._stop);
         for( Node n : _code._start._outputs )
             if( n instanceof FunNode fun ) {
                 int x = rpo._len;
-                //_rpo_cfg2(fun, visit, rpo, looptail);
                 _rpo_cfg(fun, visit, rpos );
                 assert rpo.at(x) instanceof ReturnNode;
             }
@@ -363,11 +363,6 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
             slide = 0;
             for( int i=0; i<len; i++ ) {
                 CFGNode bb = _code._cfg.at(i);
-                // Functions pad to align 16
-                if( bb instanceof FunNode ) {
-                    int newStart = _opStart[bb._nid]+slide;
-                    slide += (newStart+15 & -16)-newStart;
-                }
                 _opStart[bb._nid] += slide;
                 // Slide down all other (non-CFG) ops in the block
                 for( Node n : bb._outputs )
@@ -391,6 +386,23 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
         }
 
 
+        // Go again, inserting padding on function headers.  Since no
+        // short-jumps span function headers, the padding will not make any
+        // short jumps fail.
+        for( int i=0; i<len; i++ ) {
+            CFGNode bb = _code._cfg.at(i);
+            // Functions pad to align 16
+            if( bb instanceof FunNode ) {
+                int newStart = _opStart[bb._nid]+slide;
+                slide += (newStart+15 & -16)-newStart;
+            }
+            _opStart[bb._nid] += slide;
+            for( Node n : bb._outputs )
+                if( n instanceof MachNode && !(n instanceof CFGNode) )
+                    _opStart[n._nid] += slide;
+        }
+
+
         // Copy/slide the bits to make space for all the longer branches
         int grow = _opStart[_code._cfg.at(len-1)._nid] - oldStarts[len-1];
         if( grow > 0 ) {        // If no short-form ops, nothing to do here
@@ -426,31 +438,71 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
     void writeConstantPool( BAOS bits, boolean patch ) {
         padN(16,bits);
 
+        // radix sort the big constants by alignment
+        Ary<Relo>[] raligns = new Ary[5];
+        for( Node op : _bigCons.keySet() ) {
+            Relo relo = _bigCons.get(op);
+            int align = relo._t.alignment();
+            Ary<Relo> relos = raligns[align]==null ? (raligns[align]=new Ary<>(Relo.class)) : raligns[align];
+            relos.add(relo);
+        }
+
+
+        // Types can be used more than once; collapse the dups
         HashMap<Type,Integer> targets = new HashMap<>();
 
-        // By log size
-        for( int log = 3; log >= 0; log-- ) {
-            // Write the 8-byte constants
-            for( Node op : _bigCons.keySet() ) {
-                Relo relo = _bigCons.get(op);
-                if( relo._t.log_size()==log ) {
-                    // Map from relo to constant start and patch
-                    Integer target = targets.get(relo._t);
-                    if( target==null ) {
-                        targets.put(relo._t,target = bits.size());
-                        // Put constant into code space.
-                        if( relo._t instanceof TypeTuple tt ) // Constant tuples put all entries
-                            for( Type tx : tt._types )
-                                addN(log,tx,bits);
-                        else
-                            addN(log,relo._t,bits);
+        // By alignment
+        for( int align = 4; align >= 0; align-- ) {
+            Ary<Relo> relos = raligns[align];
+            if( relos == null ) continue;
+            for( Relo relo : relos ) {
+                // Map from relo to constant start and patch
+                Integer target = targets.get(relo._t);
+                if( target==null ) {
+                    targets.put(relo._t,target = bits.size());
+                    // Write constant into constant pool
+                    switch( relo._t ) {
+                    case TypeTuple  tt -> cpool(align,bits,tt);
+                    case TypeStruct ts -> cpool(bits,ts);
+                    // Simple primitive (e.g. larger int, float)
+                    default -> addN(align,relo._t,bits);
                     }
-                    relo._target = target;
-                    relo._opStart= _opStart[op._nid];
-                    // Go ahead and locally patch in-memory
-                    if( patch )
-                        ((RIPRelSize)op).patch(this, relo._opStart, _opLen[op._nid], relo._target - relo._opStart);
                 }
+                // Record target address and opcode start
+                relo._target = target;
+                relo._opStart= _opStart[relo._op._nid];
+                // Go ahead and locally patch in-memory
+                if( patch )
+                    ((RIPRelSize)relo._op).patch(this, relo._opStart, _opLen[relo._op._nid], relo._target - relo._opStart);
+            }
+        }
+    }
+
+    // Constant tuples put all entries at same alignment
+    private void cpool(int align, BAOS bits, TypeTuple tt) {
+        for( Type tx : tt._types )
+            addN(align,tx,bits);
+    }
+
+    // Structs use internal field layout
+    private void cpool( BAOS bits, TypeStruct ts ) {
+        // Field order by offset
+        int[] layout = ts.layout();
+        int off=0; // offset in the struct
+        for( int fn=0; fn<ts._fields.length; fn++ ) {
+            Field f  = ts._fields[layout[fn]];
+            int foff = ts. offset(layout[fn]);
+            // Pad up to field
+            while( off < foff ) { bits.write(0); off++; };
+            // Constant array fields are special
+            if( f._fname=="[]" ) {   // Must be a constant array
+                ts._con.write(bits); // Write the constant array bits
+                off += ts._con.len();
+            } else {
+                int log = f._type.log_size();
+                if( f._fname=="#" )  addN(log,ts._con.len(),bits); // Must be a constant array
+                else                 addN(log,f._type      ,bits);
+                off += 1<<log;
             }
         }
     }
@@ -459,14 +511,16 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
     // A series of libc/external calls that Simple can link against in a JIT.
     // Since no runtime in the JVM process, using magic numbers for the CPU
     // emulators to pick up on.
-    public static int SENTINAL_CALLOC = -4;
+    public static int SENTINEL_CALLOC = -4;
+    public static int SENTINEL_WRITE  = -8;
 
     void patchGlobalRelocations() {
         for( Node src : _externals.keySet() ) {
             int start  = _opStart[src._nid];
             String dst =  _externals.get(src);
             int target = switch( dst ) {
-            case "calloc" -> SENTINAL_CALLOC;
+            case "calloc" -> SENTINEL_CALLOC;
+            case "write"  -> SENTINEL_WRITE ;
             default -> throw Utils.TODO();
             };
             ((RIPRelSize)src).patch(this, start, _opLen[src._nid], target - start);
diff --git a/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java b/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java
index 447a6df1..530336d6 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/GlobalCodeMotion.java
@@ -32,7 +32,6 @@ public abstract class GlobalCodeMotion {
 
     // Post-Order of CFG
     private static void _rpo_cfg(CFGNode def, Node use, BitSet visit, Ary<CFGNode> rpo) {
-        if( use instanceof CallNode call ) call.unlink_all();
         if( !(use instanceof CFGNode cfg) || visit.get(cfg._nid) )
             return;             // Been there, done that
         if( def instanceof ReturnNode && use instanceof CallEndNode )
diff --git a/src/main/java/com/seaofnodes/simple/codegen/IFG.java b/src/main/java/com/seaofnodes/simple/codegen/IFG.java
index bc5fae8d..89850c8c 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/IFG.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/IFG.java
@@ -409,7 +409,7 @@ abstract public class IFG {
         int best=sptr;
         int bestScore = pickRiskyScore(color_stack[best]);
         for( int i=sptr+1; i<color_stack.length; i++ ) {
-            if( bestScore == 999999 ) return best; // Already max score
+            if( bestScore == 1000000 ) return best; // Already max score
             int iScore = pickRiskyScore(color_stack[i]);
             if( iScore > bestScore )
                 { best = i; bestScore = iScore; }
@@ -426,13 +426,25 @@ abstract public class IFG {
     // Picking a live range that is very close to coloring might allow it to
     // color despite being risky.
     private static int pickRiskyScore( LRG lrg ) {
+        // Pick single-def clonables that are not right next to their single-use.
+        // Failing to color these will clone them closer to their uses.
+        if( !lrg._multiDef && lrg._machDef!=null && lrg._machUse!=null && lrg._machDef.isClone() ) {
+            Node def = (Node)lrg._machDef;
+            Node use = (Node)lrg._machUse;
+            CFGNode cfg = def.cfg0();
+            if( lrg._multiUse || cfg != use.cfg0() || // Many uses or different blocks OR
+              // Same block, but not close
+              cfg._outputs.find(def)+1 < cfg._outputs.find(use) )
+                return 1000000;
+        }
+
         // Always pick callee-save registers as being very large area recovered
         // and very cheap to spill.
         if( lrg._machDef instanceof CalleeSaveNode )
-            return 999998;
+            return 1000000-2-lrg._mask.firstReg();
         if( lrg._splitDef != null && lrg._splitDef.in(1) instanceof CalleeSaveNode &&
             lrg._splitUse != null && lrg._splitUse.out(0) instanceof ReturnNode )
-            return 999999;
+            return 1000000-1;
 
         // TODO: cost/benefit model.  Perhaps counting loop-depth (freq) of def/use for cost
         // and "area" for benefit
@@ -443,36 +455,39 @@ abstract public class IFG {
         if( mask.size1() ) return reg;
         // Check chain of splits up the def-chain.  Take first allocated
         // register, and if it's available in the mask, take it.
-        Node defSplit = lrg._splitDef, useSplit = lrg._splitUse;
-        int tidx, cnt=0;
+        Node def = lrg._splitDef, use = lrg._splitUse;
+        int tidx=0, cnt=0;
 
-        while( (tidx=biasable(defSplit)) != 0 || biasable(useSplit) != 0 ) {
+        while( def != null || use != null ) {
             if( cnt++ > 10 ) break;
 
-            if( tidx != 0 ) {
-                short bias = biasColor( alloc, defSplit, mask );
+            if( def != null ) {
+                short bias = biasColor( alloc, def, mask );
                 if( bias >= 0 ) return bias; // Good bias
-                if( bias == -2 ) defSplit = null; // Kill this side, no more searching
-            } else defSplit = null;
+                if( bias == -2 ) def = null; // Kill this side, no more searching
+                else if( (tidx=biasable(def)) == 0 ) def = null;
+            }
 
-            if( biasable(useSplit) != 0 ) {
-                short bias = biasColor( alloc, useSplit, mask );
+            if( use != null ) {
+                short bias = biasColor( alloc, use, mask );
                 if( bias >= 0 ) return bias; // Good bias
-                if( bias == -2 ) useSplit = null; // Kill this side, no more searching
-            } else useSplit = null;
+                if( bias == -2 ) use = null; // Kill this side, no more searching
+                else if( biasable(use)==0 ) use = null;
+            }
 
-            if( defSplit != null ) {
-                short bias = biasColorNeighbors( alloc, defSplit, mask );
+            if( def != null ) {
+                short bias = biasColorNeighbors( alloc, def, mask );
                 if( bias >= 0 ) return bias;
                 // Advance def side
-                defSplit = defSplit.in(tidx);
-                if( alloc.lrg(defSplit)==null ) defSplit=null;
+                def = def.in(tidx);
+                if( alloc.lrg(def)==null ) def=null;
             }
 
-            if( useSplit != null ) {
-                short bias = biasColorNeighbors( alloc, useSplit, mask );
+            if( use != null ) {
+                short bias = biasColorNeighbors( alloc, use, mask );
                 if( bias >= 0 ) return bias;
-                useSplit = useSplit.out(0);
+                use = use.out(0);
+                if( biasable(use)==0 ) use=null;
             }
 
         }
@@ -481,7 +496,7 @@ abstract public class IFG {
 
     private static int biasable(Node split) {
         if( split instanceof SplitNode ) return 1; // Yes biasable, advance is slot 1
-        if( split instanceof PhiNode ) return 1;   // Yes biasable, advance is slot 1
+        if( split instanceof PhiNode phi ) return phi.region() instanceof LoopNode ? 2 : 1; // Prefer the backedge in loops
         if( !(split instanceof MachNode mach) ) return 0; // Not biasable
         return mach.twoAddress();                         // Only biasable if 2-addr
     }
diff --git a/src/main/java/com/seaofnodes/simple/codegen/Machine.java b/src/main/java/com/seaofnodes/simple/codegen/Machine.java
index 2766414f..a95faefc 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/Machine.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/Machine.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple.codegen;
 
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.TypeFunPtr;
+import com.seaofnodes.simple.type.TypeInteger;
 
 abstract public class Machine {
     // Human readable machine name.  Something like "x86-64" or "arm" or "risc5"
@@ -94,4 +95,14 @@ Pre-alloc               Post-Alloc    SP+48   RPC
     // registers.
     public abstract short maxArgSlot(TypeFunPtr tfp);
 
+    // Only the declared C result width describes the physical return register.
+    // Simple functions already return canonical full-width integer values.
+    protected static TypeInteger cReturn(ProjNode prj) {
+        if( prj._idx==2 && prj.in(0) instanceof CallEndNode cend &&
+            cend.call().fptr() instanceof ExternNode ext &&
+            ((TypeFunPtr)ext._con).ret() instanceof TypeInteger ret && ret.log_size()<3 )
+            return ret;
+        return null;
+    }
+
 }
diff --git a/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java b/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java
index dd3d2acb..5a641490 100644
--- a/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java
+++ b/src/main/java/com/seaofnodes/simple/codegen/RegAlloc.java
@@ -172,7 +172,7 @@ public class RegAlloc {
             }
         // Cache reg masks for New and Call
         for( CFGNode bb : _code._cfg ) {
-            if( bb instanceof CallEndNode cend ) cend.cacheRegs(_code);
+            if( bb instanceof CallEndMach cend ) cend.cacheRegs(_code);
             for( Node n : bb._outputs )
                 if( n instanceof NewNode nnn ) nnn.cacheRegs(_code);
         }
@@ -467,16 +467,17 @@ public class RegAlloc {
         if( def._type==Type.TOP ) return;
         // Effective block for use
         CFGNode cfg = n instanceof PhiNode phi ? phi.region().cfg(i) : n.cfg0();
+        // Use-side RegMask, if available
+        RegMask umask = n instanceof MachNode mach ? mach.regmap(i) : null;
         // Def is a split ?
         if( skip && def instanceof SplitNode ) {
-            boolean singleReg = n instanceof MachNode mach && mach.regmap(i)!=null && mach.regmap(i).size1();
+            boolean singleReg = umask!=null && umask.size1();
             // Same block, multiple registers, split is only used by n,
             // assume this is good enough and do not split again.
             if( cfg==def.cfg0() && def.nOuts()==1 && !singleReg )
                 return;
         }
-        RegMask use = n instanceof MachNode mach ? mach.regmap(i) : null;
-        makeSplit(def,kind,round,lrg,use).insertBefore(n, i);
+        makeSplit(def,kind,round,lrg,umask).insertBefore(n, i);
         // Skip split-of-split same block
         if( skip && def instanceof SplitNode && cfg==def.cfg0() )
             n.in(i).setDefOrdered(1,def.in(1));
@@ -523,13 +524,13 @@ public class RegAlloc {
     private void postColor() {
         int maxReg = -1;
         for( CFGNode bb : _code._cfg ) { // For all ops
-            if( bb instanceof FunNode fun )
+            if( bb instanceof FunNode )
                 maxReg = -1;   // Reset for new function
             // Compute frame size, based on arguments and largest reg seen
             if( bb instanceof ReturnNode ret )
                 ret.fun().computeFrameAdjust(_code,maxReg);
             // Raise frame size by max stack args passed, even if ignored
-            if( bb instanceof CallEndNode cend )
+            if( bb instanceof CallEndMach cend )
                 maxReg = Math.max(maxReg,cend._xslot);
 
             for( int j=0; j<bb.nOuts(); j++ ) {
diff --git a/src/main/java/com/seaofnodes/simple/node/AddNode.java b/src/main/java/com/seaofnodes/simple/node/AddNode.java
index 62b33ada..3a5528ef 100644
--- a/src/main/java/com/seaofnodes/simple/node/AddNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/AddNode.java
@@ -1,41 +1,27 @@
 package com.seaofnodes.simple.node;
 
-
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.*;
 
+import java.util.BitSet;
 
 import static com.seaofnodes.simple.Parser.con;
 
-public class AddNode extends Node {
+public class AddNode extends ArithNode {
     public AddNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
 
     @Override public String label() { return "Add"; }
-
-    @Override protected String format() { return "(%1+%2)"; }
-
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if( t1 instanceof TypeInteger i1 &&
-            t2 instanceof TypeInteger i2 ) {
-            if (i1.isConstant() && i2.isConstant())
-                return TypeInteger.constant(i1.value()+i2.value());
-            // Fold ranges like {0-1} + {2-3} into {2-4}.
-            if( !overflow(i1._min,i2._min) &&
-                !overflow(i1._max,i2._max) )
-                return TypeInteger.make(i1._min+i2._min,i1._max+i2._max);
-        }
+    @Override public String op() { return "+"; }
+
+    @Override long doOp( long x, long y ) { return x + y; }
+    @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
+        // Fold ranges like {0-1} + {2-3} into {2-4}.
+        if( !overflow(x._min,y._min) &&
+            !overflow(x._max,y._max) )
+            return TypeInteger.make(x._min+y._min,x._max+y._max);
         return TypeInteger.BOT;
     }
 
-    static boolean overflow( long x, long y ) {
-        if( (x ^    y ) < 0 ) return false; // unequal signs, never overflow
-        return (x ^ (x + y)) < 0; // sum has unequal signs, so overflow
-    }
     @Override
     public Node idealize () {
         Node lhs = in(1);
@@ -106,7 +92,7 @@ public class AddNode extends Node {
         if( spine_cmp(lhs.in(2),rhs,this) )
             return new AddNode(new AddNode(lhs.in(1),rhs).peephole(),lhs.in(2));
 
-        return null;
+        return super.idealize();
     }
 
     // Rotation is only valid for associative ops, e.g. Add, Mul, And, Or, Xor.
@@ -183,10 +169,4 @@ public class AddNode extends Node {
 
     @Override Node copy(Node lhs, Node rhs) { return new AddNode(lhs,rhs); }
     @Override Node copyF() { return new AddFNode(null,null); }
-    @Override public Parser.ParseException err() {
-        if( in(1)._type.isHigh() || in(2)._type.isHigh() ) return null;
-        if( !(in(1)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+label()+"' " + in(1)._type,null);
-        if( !(in(2)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+label()+"' " + in(2)._type,null);
-        return null;
-    }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/AndNode.java b/src/main/java/com/seaofnodes/simple/node/AndNode.java
index b425a6ce..9957472b 100644
--- a/src/main/java/com/seaofnodes/simple/node/AndNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/AndNode.java
@@ -4,28 +4,16 @@ import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
 
-import java.util.BitSet;
-
-public class AndNode extends LogicalNode {
+public class AndNode extends ArithNode {
     public AndNode(Parser.Lexer loc, Node lhs, Node rhs) { super(loc, lhs, rhs); }
 
     @Override public String label() { return "And"; }
     @Override public String op() { return "&"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if( t1 instanceof TypeInteger i0 &&
-            t2 instanceof TypeInteger i1 ) {
-            if( i0.isConstant() && i1.isConstant() )
-                return TypeInteger.constant(i0.value()&i1.value());
-            // Sharpen allowed bits if either value is narrowed
-            long mask = i0.mask() & i1.mask();
-            return mask < 0 ? TypeInteger.BOT : TypeInteger.make(0,mask);
-        }
-        return TypeInteger.BOT;
+    @Override long doOp( long x, long y ) { return x & y; }
+    @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
+        // Sharpen allowed bits if either value is narrowed
+        long mask = x.mask() & y.mask();
+        return mask < 0 ? TypeInteger.BOT : TypeInteger.make(0,mask);
     }
 
     @Override
@@ -51,9 +39,10 @@ public class AndNode extends LogicalNode {
         // Do we have ((x & (phi cons)) & (phi cons)) ?
         // Push constant up through the phi: x & (phi con0&con0 con1&con1...)
         Node phicon = AddNode.phiCon(this,true);
-        if( phicon!=null ) return phicon;
+        if( phicon!=null )
+            return phicon;
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new AndNode(_loc,lhs,rhs); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/ArithNode.java b/src/main/java/com/seaofnodes/simple/node/ArithNode.java
new file mode 100644
index 00000000..e94ccbc6
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/ArithNode.java
@@ -0,0 +1,95 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.print.ExprPrinter;
+
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.Utils;
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeInteger;
+
+public abstract class ArithNode extends Node {
+    // Source location for late reported errors
+    Parser.Lexer _loc;
+
+    public ArithNode( Parser.Lexer loc, Node lhs, Node rhs) { super(null, lhs, rhs); _loc = loc; }
+    abstract String op();
+
+    @Override protected ExprPrinter<Node> _print1(ExprPrinter<Node> p) {
+        return p.open().n(in(1)).p(op()).n(in(2)).close();
+    }
+
+    abstract long doOp(long x, long y);
+    abstract TypeInteger doOp(TypeInteger x, TypeInteger y);
+
+    // Generic airthmetic op math: high returns high; low returns low; 2
+    // constants fold; only 2 non-constants call specialized math.
+    @Override
+    public final TypeInteger compute() {
+        Type t1 = in(1)._type, t2 = in(2)._type;
+        if( t1.isHigh() || t2.isHigh() )
+            return TypeInteger.TOP;
+        if( t1 instanceof TypeInteger x &&
+            t2 instanceof TypeInteger y )
+            return x.isConstant() && y.isConstant()
+                ? con(x,y)
+                : doOp(x,y);
+        return TypeInteger.BOT;
+    }
+
+    private TypeInteger con( Type t1, Type t2 ) {
+        return TypeInteger.constant( doOp( ((TypeInteger)t1).value(), ((TypeInteger)t2).value()) );
+    }
+
+    // Check for "op(Phi(con,x),Phi(con,y))" and push-up through the Phi.
+    // Note that this is the exact reverse of Phi pulling a common op down
+    // to reduce total op-count.  We don't get in an endless push-up
+    // push-down peephole cycle because the constants all fold first.
+    // Returns "Phi(op(con,con),op(x,y))".
+
+    // This check is slightly different from the
+
+    // Expected to be called after other ideal checks are done.
+    @Override public Node idealize() {
+        if( in(1) instanceof PhiNode lhs &&
+            in(2) instanceof PhiNode rhs &&
+            lhs.nIns() >= 2 && !lhs.inProgress() &&
+            lhs.region()==rhs.region() ) {
+            // Profit check: only 1 instance of `this` will remain, all the
+            // others will fold to constants.
+            int cnt=0;
+            for( int i=1; i<lhs.nIns(); i++ )
+                if( isCon(lhs,rhs,i) )
+                    cnt++;
+            if( lhs.nIns()-1 - cnt <= 1 ) {
+                // Profit!  Push up-phi and fold
+                Node[] ns = new Node[lhs.nIns()];
+                ns[0] = lhs.in(0);
+                for( int i=1; i<lhs.nIns(); i++ ) {
+                    ns[i] = isCon(lhs,rhs,i)
+                        ? new ConstantNode(con(lhs.in(i)._type, rhs.in(i)._type)).peephole()
+                        : copy(lhs.in(i), rhs.in(i)).peephole();
+                }
+                String label = lhs._label==rhs._label ? lhs._label : lhs._label + rhs._label;
+                return new PhiNode(label,lhs._declaredType,ns).peephole();
+            }
+        }
+        return null;
+    }
+
+    static boolean isCon( PhiNode lhs, PhiNode rhs, int i ) {
+        return lhs.in(i)._type.isConstant() && rhs.in(i)._type.isConstant();
+    }
+
+
+    static boolean overflow( long x, long y ) {
+        if( (x ^    y ) < 0 ) return false; // unequal signs, never overflow
+        return (x ^ (x + y)) < 0; // sum has unequal signs, so overflow
+    }
+
+    @Override public Parser.ParseException err() {
+        if( in(1)._type.isHigh() || in(2)._type.isHigh() ) return null;
+        if( !(in(1)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+op()+"' " + in(1)._type,_loc);
+        if( !(in(2)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+op()+"' " + in(2)._type,_loc);
+        return null;
+    }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/BoolNode.java b/src/main/java/com/seaofnodes/simple/node/BoolNode.java
index d6a126f5..21ac59d3 100644
--- a/src/main/java/com/seaofnodes/simple/node/BoolNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/BoolNode.java
@@ -123,9 +123,24 @@ abstract public class BoolNode extends Node {
         Node copyF() { return new LEF(null,null); }
     }
 
-    public static class EQF extends EQ { public EQF(Node lhs, Node rhs) { super(lhs,rhs); } boolean doOp(double lhs, double rhs) { return lhs == rhs; } public boolean isFloat() { return true; } }
-    public static class LTF extends LT { public LTF(Node lhs, Node rhs) { super(lhs,rhs); } boolean doOp(double lhs, double rhs) { return lhs <  rhs; } public boolean isFloat() { return true; } }
-    public static class LEF extends LE { public LEF(Node lhs, Node rhs) { super(lhs,rhs); } boolean doOp(double lhs, double rhs) { return lhs <= rhs; } public boolean isFloat() { return true; } }
+    public static class EQF extends EQ {
+        public EQF(Node lhs, Node rhs) { super(lhs,rhs); }
+        @Override boolean doOp(double lhs, double rhs) { return lhs == rhs; }
+        @Override public boolean isFloat() { return true; }
+        @Override Node copy(Node lhs, Node rhs) { return new EQF(lhs,rhs); }
+    }
+    public static class LTF extends LT {
+        public LTF(Node lhs, Node rhs) { super(lhs,rhs); }
+        @Override boolean doOp(double lhs, double rhs) { return lhs <  rhs; }
+        @Override public boolean isFloat() { return true; }
+        @Override Node copy(Node lhs, Node rhs) { return new LTF(lhs,rhs); }
+    }
+    public static class LEF extends LE {
+        public LEF(Node lhs, Node rhs) { super(lhs,rhs); }
+        @Override boolean doOp(double lhs, double rhs) { return lhs <= rhs; }
+        @Override public boolean isFloat() { return true; }
+        @Override Node copy(Node lhs, Node rhs) { return new LEF(lhs,rhs); }
+    }
 
     // Unsigned less that, for range checks.  Not directly user writable.
     public static class ULT extends BoolNode {
diff --git a/src/main/java/com/seaofnodes/simple/node/CFGNode.java b/src/main/java/com/seaofnodes/simple/node/CFGNode.java
index 47dfa311..4f346ee3 100644
--- a/src/main/java/com/seaofnodes/simple/node/CFGNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/CFGNode.java
@@ -133,7 +133,19 @@ public abstract class CFGNode extends Node {
     // Tag all CFG Nodes with their containing LoopNode; LoopNodes themselves
     // also refer to *their* containing LoopNode, as well as have their depth.
     // Start contains the function bodies at depth 0; real loops add depth.
-    public void buildLoopTree(StopNode stop) {
+    public void buildLoopTree(StartNode start, StopNode stop) {
+        // Unlink all linked calls.  This can remove RPC constants which
+        // shuffled the StartNode outputs so requires a while loop.
+        boolean done=false;
+        while(!done) {
+            done = true;
+            for( Node use : start._outputs )
+                if( use instanceof FunNode fun )
+                    for( Node c : fun._inputs )
+                        if( c instanceof CallNode call )
+                            { call.unlink_all(); done=false; }
+        }
+
         _ltree = stop._ltree = Parser.XCTRL._ltree = new LoopTree((StartNode)this);
         _bltWalk(2,null,stop, new BitSet());
     }
diff --git a/src/main/java/com/seaofnodes/simple/node/CallEndMach.java b/src/main/java/com/seaofnodes/simple/node/CallEndMach.java
new file mode 100644
index 00000000..47cab07a
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/CallEndMach.java
@@ -0,0 +1,36 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.codegen.*;
+
+public class CallEndMach extends CallEndNode implements MachNode {
+    public CallEndMach( CallEndNode n ) { super(n); }
+    // MachNode specifics, shared across all CPUs
+    public int _xslot;
+    private RegMask _retMask;
+    private RegMask _kills;
+    public void cacheRegs(CodeGen code) {
+        // Return mask depends on TFP (either GPR or FPR)
+        _retMask = code._mach.retMask(call().tfp());
+        // Kill mask is all caller-saves, and any mirror stack slots for args
+        // in registers.
+        RegMaskRW kills = code._callerSave.copy();
+        // Start of stack slots
+        int maxReg = code._mach.regs().length;
+        // Incoming function arg slots, all low numbered in the RA
+        int fslot = fun()._maxArgSlot;
+        // Killed slots for this calls outgoing args
+        int xslot = code._mach.maxArgSlot(call().tfp());
+        _xslot = (maxReg+fslot)+xslot;
+        for( int i=0; i<xslot; i++ )
+            kills.set((maxReg+fslot)+i);
+        _kills = kills;
+    }
+    public String op() { return "cend"; }
+    public RegMask regmap(int i) { return null; }
+    public RegMask outregmap() { return null; }
+    public RegMask outregmap(int idx) { return idx==2  ? _retMask : null; }
+    public RegMask killmap() { return _kills; }
+    public void encoding( Encoding enc ) { }
+    public void asm(CodeGen code, SB sb) {  }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/CallEndNode.java b/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
index 47e80ca9..94f5ee49 100644
--- a/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/CallEndNode.java
@@ -24,6 +24,11 @@ public class CallEndNode extends CFGNode implements MultiNode {
 
     public CallNode call() { return (CallNode)in(0); }
 
+    @Override public CFGNode idom(Node dep) {
+        // Folding the idom is the one inlining Return
+        return _folding ? cfg(1) : super.idom(dep);
+    }
+
     @Override
     protected ExprPrinter<Node> _print1(ExprPrinter<Node> p) {
         p.p("cend( ");
@@ -38,7 +43,6 @@ public class CallEndNode extends CFGNode implements MultiNode {
         if( !(in(0) instanceof CallNode call) )
             return TypeTuple.RET.dual();
         Type ret = Type.BOTTOM;
-        TypeMem mem = TypeMem.BOT;
         if( addDep(call.fptr())._type instanceof TypeFunPtr tfp ) {
             ret = tfp.ret();
             // Here, if I can figure out I've found *all* callers, then I can meet
@@ -71,10 +75,10 @@ public class CallEndNode extends CFGNode implements MultiNode {
                     assert fun.in(1) instanceof StartNode && fun.in(2)==call;
                     // Disallow self-recursive inlining (loop unrolling by another name)
                     CFGNode idom = call;
-                    while( !(idom instanceof FunNode) )
+                    while( idom!=null && !(idom instanceof FunNode) )
                         idom = idom.idom();
                     // Inline?
-                    if( idom != fun ) {
+                    if( idom != null && idom != fun ) {
                         // Trivial inline: rewrite
                         _folding = true;
                         // Rewrite Fun so the normal RegionNode ideal collapses
@@ -196,33 +200,4 @@ public class CallEndNode extends CFGNode implements MultiNode {
         return _folding ? in(1).in(idx) : null;
     }
 
-    // ------------
-    // MachNode specifics, shared across all CPUs
-    public int _xslot;
-    private RegMask _retMask;
-    private RegMask _kills;
-    public void cacheRegs(CodeGen code) {
-        // Return mask depends on TFP (either GPR or FPR)
-        _retMask = code._mach.retMask(call().tfp());
-        // Kill mask is all caller-saves, and any mirror stack slots for args
-        // in registers.
-        RegMaskRW kills = code._callerSave.copy();
-        // Start of stack slots
-        int maxReg = code._mach.regs().length;
-        // Incoming function arg slots, all low numbered in the RA
-        int fslot = fun()._maxArgSlot;
-        // Killed slots for this calls outgoing args
-        int xslot = code._mach.maxArgSlot(call().tfp());
-        _xslot = (maxReg+fslot)+xslot;
-        for( int i=0; i<xslot; i++ )
-            kills.set((maxReg+fslot)+i);
-        _kills = kills;
-    }
-    public String op() { return "cend"; }
-    public RegMask regmap(int i) { return null; }
-    public RegMask outregmap() { return null; }
-    public RegMask outregmap(int idx) { return idx==2  ? _retMask : null; }
-    public RegMask killmap() { return _kills; }
-    public void encoding( Encoding enc ) { }
-    public void asm(CodeGen code, SB sb) {  }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/CallNode.java b/src/main/java/com/seaofnodes/simple/node/CallNode.java
index 70c71d43..3bf873fa 100644
--- a/src/main/java/com/seaofnodes/simple/node/CallNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/CallNode.java
@@ -34,7 +34,8 @@ public class CallNode extends CFGNode {
     public String name() {
         if( fptr()._type instanceof TypeFunPtr tfp && tfp.isConstant() && tfp.notNull() ) {
             FunNode fun = CodeGen.CODE.link(tfp);
-            return fun==null ? null : fun._name;
+            if( fun !=null ) return fun._name;
+            if( fptr() instanceof ExternNode ex )  return ex._extern;
         }
         return null;
     }
@@ -164,6 +165,9 @@ public class CallNode extends CFGNode {
             if( !arg(i+2)._type.isa(tfp.arg(i)) || !arg(i+2)._type.accessISA(tfp.arg(i)) )
                 return Parser.error( "Argument #"+i+" isa "+arg(i+2)._type+", but must be a "+tfp.arg(i), _loc);
 
+        if( tfp.fidxs() < 0 )
+            throw Utils.TODO(); // Infinite unknown TFPs?  Should be fairly precise CG
+
         return null;
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/CastARM.java b/src/main/java/com/seaofnodes/simple/node/CastMach.java
index a5a4e112..92822433 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/arm/CastARM.java
+++ b/src/main/java/com/seaofnodes/simple/node/CastMach.java
@@ -1,18 +1,19 @@
-package com.seaofnodes.simple.node.cpus.arm;
+package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.SB;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.codegen.Encoding;
 import com.seaofnodes.simple.codegen.RegMask;
-import com.seaofnodes.simple.node.CastNode;
-import com.seaofnodes.simple.node.MachNode;
 
-public class CastARM extends CastNode implements MachNode {
-    public CastARM( CastNode cast ) { super(cast); }
+/**
+ * Cast a pointer to read-only
+ */
+public class CastMach extends CastNode implements MachNode {
+    public CastMach( CastNode n ) { super(n); }
     @Override public String op() { return label(); }
     @Override public RegMask regmap(int i) { assert i==1; return RegMask.FULL; }
     @Override public RegMask outregmap() { return RegMask.FULL; }
     @Override public int twoAddress( ) { return 1; }
     @Override public void encoding( Encoding enc ) { }
-    @Override public void asm(CodeGen code, SB sb) { _t.print(sb.p(code.reg(in(1))).p(" isa ")); }
+    @Override public void asm(CodeGen code, SB sb) { sb.p(code.reg(in(1))); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/CastNode.java b/src/main/java/com/seaofnodes/simple/node/CastNode.java
index 5598acd8..8ae7b327 100644
--- a/src/main/java/com/seaofnodes/simple/node/CastNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/CastNode.java
@@ -6,6 +6,8 @@ import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.type.TypeMemPtr;
+
 
 // Upcast (join) the input to a t.  Used after guard test to lift an input.
 // Can also be used to make a type-assertion if ctrl is null.
@@ -34,6 +36,9 @@ public class CastNode extends Node {
 
     @Override
     public Type compute() {
+        // Cast array to int
+        if( _t == TypeInteger.BOT && in(1)._type instanceof TypeMemPtr tmp && tmp._obj.isAry() )
+            return _t;
         return in(1)._type.join(_t);
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/ConstantNode.java b/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
index c4a41e5d..d3ac24a7 100644
--- a/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/ConstantNode.java
@@ -33,6 +33,10 @@ public class ConstantNode extends Node {
     public static Node make( Type type ) {
         if( type==Type. CONTROL ) return new CtrlNode();
         if( type==Type.XCONTROL ) return new XCtrlNode();
+        if( type instanceof TypeFunPtr tfp && tfp.isConstant() && tfp.notNull() ) {
+            FunNode fun = CodeGen.CODE.link(tfp);
+            if( fun!=null && !fun.isDead() ) return new FunPtrNode(tfp,fun.ret());
+        }
         return new ConstantNode(type);
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/DivNode.java b/src/main/java/com/seaofnodes/simple/node/DivNode.java
index 70631c0a..7b5ae16c 100644
--- a/src/main/java/com/seaofnodes/simple/node/DivNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/DivNode.java
@@ -1,28 +1,17 @@
 package com.seaofnodes.simple.node;
 
-
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
+import java.util.BitSet;
 
-public class DivNode extends Node {
+public class DivNode extends ArithNode {
     public DivNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
 
     @Override public String label() { return "Div"; }
+    @Override public String op() { return "//"; }
 
-    @Override protected String format() { return "(%1/%2)"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if( t1 instanceof TypeInteger i1 &&
-            t2 instanceof TypeInteger i2 ) {
-            if (i1.isConstant() && i2.isConstant())
-                return i2.value() == 0
-                    ? TypeInteger.ZERO
-                    : TypeInteger.constant(i1.value()/i2.value());
-        }
+    @Override long doOp( long x, long y ) { return y==0 ? 0 : x / y; }
+    @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
         return TypeInteger.BOT;
     }
 
@@ -31,7 +20,7 @@ public class DivNode extends Node {
         // Div of 1.
         if( in(2)._type == TypeInteger.TRUE && in(1)._type instanceof TypeInteger )
             return in(1);
-        return null;
+        return super.idealize();
     }
 
     @Override Node copy(Node lhs, Node rhs) { return new DivNode(lhs,rhs); }
diff --git a/src/main/java/com/seaofnodes/simple/node/ExternNode.java b/src/main/java/com/seaofnodes/simple/node/ExternNode.java
new file mode 100644
index 00000000..093cc2cb
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/ExternNode.java
@@ -0,0 +1,21 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.Parser;
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.type.Type;
+import com.seaofnodes.simple.type.TypeFunPtr;
+import java.util.BitSet;
+
+/**
+   A constant with external linkage.
+ */
+
+public class ExternNode extends ConstantNode {
+    public final String _extern;
+    public ExternNode(Type t, String ex) { super(t); _extern = ex; }
+
+    @Override public String  label() { return "#"+_con+":"+_extern; }
+
+    @Override public boolean eq(Node n) { return this==n; }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/FunNode.java b/src/main/java/com/seaofnodes/simple/node/FunNode.java
index eb1e8259..5f67f859 100644
--- a/src/main/java/com/seaofnodes/simple/node/FunNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/FunNode.java
@@ -22,7 +22,7 @@ public class FunNode extends RegionNode {
 
     public String _name;        // Debug name
 
-    public FunNode( Parser.Lexer loc, TypeFunPtr sig, Node... nodes ) { super(loc,nodes); _sig = sig; }
+    public FunNode( Parser.Lexer loc, TypeFunPtr sig, String name, Node... nodes ) { super(loc,nodes); _name=name; _sig = sig; }
     public FunNode( FunNode fun ) {
         super( fun, fun==null ? null : fun._loc );
         if( fun!=null ) {
@@ -60,6 +60,16 @@ public class FunNode extends RegionNode {
     public void setRet(ReturnNode ret) { _ret=ret; }
     public ReturnNode ret() { assert _ret!=null; return _ret; }
 
+    // Direct calls are known; any other use of an address may have unknown callers.
+    public boolean hasPtr() {
+        for( Node use : ret()._outputs )
+            if( use instanceof FunPtrNode )
+                for( Node user : use._outputs )
+                    if( !(user instanceof CallNode call) || call.fptr()!=use ||
+                        call._inputs.find(use)!=call.nIns()-1 ) return true;
+        return false;
+    }
+
     // Signature can improve over time
     public TypeFunPtr sig() { return _sig; }
     public void setSig( TypeFunPtr sig ) {
@@ -70,10 +80,17 @@ public class FunNode extends RegionNode {
         }
     }
 
+    public void setName( String name ) {
+        if( _name==null ) _name=name;
+        else _name += "."+name;
+    }
+
     @Override
     public Type compute() {
         // Only dead if no callers after SCCP
-        return Type.CONTROL;
+        if( unknownCallers() )
+            return Type.CONTROL;
+        return super.compute();
     }
 
     @Override
@@ -117,10 +134,10 @@ public class FunNode extends RegionNode {
     // unless folding then just a ID on input#1
     @Override public int idepth() { return _folding ? super.idepth() : 1; }
     // Bypass Region idom, always assume idom is Start
-    @Override public CFGNode idom(Node dep) { return cfg(1); }
+    @Override public CFGNode idom(Node dep) { return _folding && nIns()==3 ? cfg(2) : cfg(1); }
 
     // Always in-progress until we run out of unknown callers
-    public boolean unknownCallers() { return in(1) instanceof StartNode; }
+    public boolean unknownCallers() { return nIns()<2 || in(1) instanceof StartNode; }
 
     @Override public boolean inProgress() { return unknownCallers(); }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java b/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java
new file mode 100644
index 00000000..43242c32
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java
@@ -0,0 +1,12 @@
+package com.seaofnodes.simple.node;
+
+import com.seaofnodes.simple.type.TypeFunPtr;
+
+// A function address keeps its body alive, even without a linked Call.
+public class FunPtrNode extends ConstantNode {
+    public FunPtrNode(TypeFunPtr tfp, ReturnNode ret) {
+        super(tfp);
+        addDef(ret);
+    }
+    public ReturnNode ret() { return (ReturnNode)in(1); }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/LogicalNode.java b/src/main/java/com/seaofnodes/simple/node/LogicalNode.java
deleted file mode 100644
index 6ac16d31..00000000
--- a/src/main/java/com/seaofnodes/simple/node/LogicalNode.java
+++ /dev/null
@@ -1,27 +0,0 @@
-package com.seaofnodes.simple.node;
-
-import com.seaofnodes.print.ExprPrinter;
-
-import com.seaofnodes.simple.Parser;
-import com.seaofnodes.simple.type.Type;
-import com.seaofnodes.simple.type.TypeInteger;
-
-public abstract class LogicalNode extends Node {
-    // Source location for late reported errors
-    Parser.Lexer _loc;
-
-    public LogicalNode(Parser.Lexer loc, Node lhs, Node rhs) { super(null, lhs, rhs); _loc = loc; }
-    abstract String op();
-
-    @Override protected ExprPrinter<Node> _print1(ExprPrinter<Node> p) {
-        return p.open().n(in(1)).p(op()).n(in(2)).close();
-    }
-
-
-    @Override public Parser.ParseException err() {
-        if( in(1)._type.isHigh() || in(2)._type.isHigh() ) return null;
-        if( !(in(1)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+op()+"' " + in(1)._type,_loc);
-        if( !(in(2)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+op()+"' " + in(2)._type,_loc);
-        return null;
-    }
-}
diff --git a/src/main/java/com/seaofnodes/simple/node/LoopNode.java b/src/main/java/com/seaofnodes/simple/node/LoopNode.java
index f86d7518..265132dc 100644
--- a/src/main/java/com/seaofnodes/simple/node/LoopNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/LoopNode.java
@@ -26,7 +26,7 @@ public class LoopNode extends RegionNode {
     }
 
     // Bypass Region idom, same as the default idom() using use in(1) instead of in(0)
-    public int idepth() { return validIDepth() ? _idepth : cacheIDepth(entry().idepth()+1); }
+    @Override public int idepth() { return validIDepth() ? _idepth : cacheIDepth(entry().idepth()+1); }
     // Bypass Region idom, same as the default idom() using use in(1) instead of in(0)
     @Override public CFGNode idom(Node dep) { return entry(); }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/MemOpNode.java b/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
index adfc80a5..db667e6d 100644
--- a/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/MemOpNode.java
@@ -78,7 +78,6 @@ public abstract class MemOpNode extends Node {
         _declaredType = Type.BOTTOM;
     }
 
-    //
     static String mlabel(String name) { return "[]".equals(name) ? "ary" : ("#".equals(name) ? "len" : name); }
     String mlabel() { return mlabel(_name); }
 
@@ -90,7 +89,7 @@ public abstract class MemOpNode extends Node {
 
     @Override protected ExprPrinter<Node> _print1(ExprPrinter<Node> p) { return _printMach(p);  }
     protected ExprPrinter<Node> _printMach(ExprPrinter<Node> p) { throw Utils.TODO(); }
-
+    public int log_size() { return _declaredType.log_size();  }
 
     // Extra conditions for factoring matching memory operations through a Phi.
     // The caller has already checked the opcode, input shape and control.
diff --git a/src/main/java/com/seaofnodes/simple/node/MinusNode.java b/src/main/java/com/seaofnodes/simple/node/MinusNode.java
index 66e26163..cd67b8fc 100644
--- a/src/main/java/com/seaofnodes/simple/node/MinusNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/MinusNode.java
@@ -17,7 +17,7 @@ public class MinusNode extends Node {
     public Type compute() {
         if( in(1)._type.isHigh() ) return TypeInteger.TOP;
         if( in(1)._type instanceof TypeInteger i0 &&
-            !(i0==TypeInteger.BOT || i0._min == Long.MIN_VALUE || i0._max == Long.MIN_VALUE) )
+            i0._min != Long.MIN_VALUE && i0._max != Long.MIN_VALUE )
             return TypeInteger.make(-i0._max,-i0._min);
         return TypeInteger.BOT;
     }
diff --git a/src/main/java/com/seaofnodes/simple/node/MulNode.java b/src/main/java/com/seaofnodes/simple/node/MulNode.java
index ac97725c..6e1dc053 100644
--- a/src/main/java/com/seaofnodes/simple/node/MulNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/MulNode.java
@@ -1,29 +1,18 @@
 package com.seaofnodes.simple.node;
 
-
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
+import java.util.BitSet;
 
-public class MulNode extends Node {
+public class MulNode extends ArithNode {
     public MulNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
 
     @Override public String label() { return "Mul"; }
+    @Override public String op() { return "*"; }
 
-    @Override protected String format() { return "(%1*%2)"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if( t1 instanceof TypeInteger i1 &&
-            t2 instanceof TypeInteger i2 ) {
-            if( i1==TypeInteger.ZERO || i2==TypeInteger.ZERO)
-                return TypeInteger.ZERO;
-            if (i1.isConstant() && i2.isConstant())
-                return TypeInteger.constant(i1.value()*i2.value());
-        }
+    @Override long doOp( long x, long y ) { return x * y; }
+    @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
         return TypeInteger.BOT;
     }
 
@@ -67,14 +56,8 @@ public class MulNode extends Node {
         Node phicon = AddNode.phiCon(this,true);
         if( phicon!=null ) return phicon;
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new MulNode(lhs,rhs); }
     @Override Node copyF() { return new MulFNode(null,null); }
-    @Override public Parser.ParseException err() {
-        if( in(1)._type.isHigh() || in(2)._type.isHigh() ) return null;
-        if( !(in(1)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+label()+"' " + in(1)._type.glb(),null);
-        if( !(in(2)._type instanceof TypeInteger) ) return Parser.error("Cannot '"+label()+"' " + in(2)._type.glb(),null);
-        return null;
-    }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/Node.java b/src/main/java/com/seaofnodes/simple/node/Node.java
index 8b0647d0..fff1ab14 100644
--- a/src/main/java/com/seaofnodes/simple/node/Node.java
+++ b/src/main/java/com/seaofnodes/simple/node/Node.java
@@ -37,7 +37,7 @@ public abstract class Node extends BaseNode<Node> implements Cloneable {
      * walked in either direction.  These outputs are typically used for
      * efficient optimizations but otherwise have no semantics meaning.
      */
-    public Ary<Node> _outputs;
+     public Ary<Node> _outputs;
 
     /**
      * Current computed type for this Node.  This value changes as the graph
@@ -59,7 +59,7 @@ public abstract class Node extends BaseNode<Node> implements Cloneable {
     // Used by any pass rewriting all Node classes but not the edges.
     Node( Node n ) {
         super(CODE.getUID()); // allocate unique dense ID
-        assert CodeGen.CODE._phase.ordinal() >= CodeGen.Phase.InstSelect.ordinal();
+        assert CodeGen.CODE._phase.ordinal() >= CodeGen.Phase.Select.ordinal();
         _inputs  = new Ary<>(n==null ? new Node[0] : n._inputs.asAry());
         _outputs = new Ary<>(Node.class);
         _type = n==null ? Type.BOTTOM : n._type;
@@ -188,7 +188,7 @@ public abstract class Node extends BaseNode<Node> implements Cloneable {
 
     // Shortcut for "popping" until n nodes.  A "pop" is basically a
     // setDef(last,null) followed by lowering the nIns() count.
-    void popUntil(int n) {
+    public void popUntil(int n) {
         unlock();
         while( nIns() > n ) {
             Node old_def = _inputs.pop();
@@ -204,9 +204,9 @@ public abstract class Node extends BaseNode<Node> implements Cloneable {
      * code elimination.
      */
     public void kill( ) {
+        assert isUnused();      // Has no uses, so it is dead
         unlock();
         moveDepsToWorklist();
-        assert isUnused();      // Has no uses, so it is dead
         _type=null;             // Flag as dead
         while( nIns()>0 ) { // Set all inputs to null, recursively killing unused Nodes
             Node old_def = _inputs.removeLast();
@@ -241,6 +241,10 @@ public abstract class Node extends BaseNode<Node> implements Cloneable {
         if( unkeep().isUnused() )
             kill();
     }
+    public void isKill() {
+        if( isUnused() )
+            kill();
+    }
 
     // Replace self with nnn in the graph, making 'this' go dead
     public void subsume( Node nnn ) {
diff --git a/src/main/java/com/seaofnodes/simple/node/OrNode.java b/src/main/java/com/seaofnodes/simple/node/OrNode.java
index 1cd8bafc..d16dd194 100644
--- a/src/main/java/com/seaofnodes/simple/node/OrNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/OrNode.java
@@ -4,24 +4,13 @@ import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
 
-import java.util.BitSet;
-
-public class OrNode extends LogicalNode {
+public class OrNode extends ArithNode {
     public OrNode(Parser.Lexer loc, Node lhs, Node rhs) { super(loc, lhs, rhs); }
 
     @Override public String label() { return "Or"; }
     @Override public String op() { return "|"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if( t1 instanceof TypeInteger i0 &&
-            t2 instanceof TypeInteger i1 ) {
-            if( i0.isConstant() && i1.isConstant() )
-                return TypeInteger.constant(i0.value()|i1.value());
-        }
+    @Override long doOp( long x, long y ) { return x | y; }
+    @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
         return TypeInteger.BOT;
     }
 
@@ -47,7 +36,7 @@ public class OrNode extends LogicalNode {
         Node phicon = AddNode.phiCon(this,true);
         if( phicon!=null ) return phicon;
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new OrNode(_loc,lhs,rhs); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/ParmNode.java b/src/main/java/com/seaofnodes/simple/node/ParmNode.java
index c3a0cf21..3e8e3711 100644
--- a/src/main/java/com/seaofnodes/simple/node/ParmNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/ParmNode.java
@@ -38,4 +38,8 @@ public class ParmNode extends PhiNode {
 
     // Always in-progress until we run out of unknown callers
     @Override public boolean inProgress() { return fun().inProgress(); }
+
+    @Override public boolean eq( Node n ) {
+        return ((ParmNode)n)._idx==_idx && super.eq(n);
+    }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/PhiNode.java b/src/main/java/com/seaofnodes/simple/node/PhiNode.java
index e075ea5c..8aa123f7 100644
--- a/src/main/java/com/seaofnodes/simple/node/PhiNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/PhiNode.java
@@ -50,7 +50,7 @@ public class PhiNode extends Node {
         // During parsing Phis have to be computed type pessimistically.
         if( r.inProgress() ) return _declaredType;
         // Set type to local top of the starting type
-        Type t = _declaredType.glb().dual();//Type.TOP;
+        Type t = _declaredType.glb(false).dual();//Type.TOP;
         for (int i = 1; i < nIns(); i++)
             // If the region's control input is live, add this as a dependency
             // to the control because we can be peeped should it become dead.
@@ -167,7 +167,7 @@ public class PhiNode extends Node {
                 }
                 PhiNode phi = j==1 && op instanceof MemOpNode mem
                     ? new MemPhiNode(_label,mem._alias,ins)
-                    : PhiNode.make(_label,t.glb(),ins);
+                    : PhiNode.make(_label,t.glb(false),ins);
                 x = phi.peephole();
             }
             cp.addDef(x);
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CastRISC.java b/src/main/java/com/seaofnodes/simple/node/ReadOnlyMach.java
index c404aaa5..86d17f9b 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CastRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/ReadOnlyMach.java
@@ -1,18 +1,19 @@
-package com.seaofnodes.simple.node.cpus.riscv;
+package com.seaofnodes.simple.node;
 
 import com.seaofnodes.simple.SB;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.codegen.Encoding;
 import com.seaofnodes.simple.codegen.RegMask;
-import com.seaofnodes.simple.node.CastNode;
-import com.seaofnodes.simple.node.MachNode;
 
-public class CastRISC extends CastNode implements MachNode {
-    public CastRISC( CastNode cast ) { super(cast); }
+/**
+ * Cast a pointer to read-only
+ */
+public class ReadOnlyMach extends ReadOnlyNode implements MachNode {
+    public ReadOnlyMach( ReadOnlyNode n ) { super(n); }
     @Override public String op() { return label(); }
     @Override public RegMask regmap(int i) { assert i==1; return RegMask.FULL; }
     @Override public RegMask outregmap() { return RegMask.FULL; }
     @Override public int twoAddress( ) { return 1; }
     @Override public void encoding( Encoding enc ) { }
-    @Override public void asm(CodeGen code, SB sb) { _t.print(sb.p(code.reg(in(1))).p(" isa ")); }
+    @Override public void asm(CodeGen code, SB sb) { sb.p(code.reg(in(1))); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/ReadOnlyNode.java b/src/main/java/com/seaofnodes/simple/node/ReadOnlyNode.java
index d79f2815..94c1b6f6 100644
--- a/src/main/java/com/seaofnodes/simple/node/ReadOnlyNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/ReadOnlyNode.java
@@ -4,7 +4,6 @@ package com.seaofnodes.simple.node;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeMemPtr;
 
-
 /**
  * Cast a pointer to read-only
  */
@@ -24,4 +23,5 @@ public class ReadOnlyNode extends Node {
             return in(1);
         return null;
     }
+
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/SarNode.java b/src/main/java/com/seaofnodes/simple/node/SarNode.java
index d321da42..429be229 100644
--- a/src/main/java/com/seaofnodes/simple/node/SarNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/SarNode.java
@@ -3,29 +3,17 @@ package com.seaofnodes.simple.node;
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-import java.util.BitSet;
 
-public class SarNode extends LogicalNode {
+public class SarNode extends ArithNode {
     public SarNode(Parser.Lexer loc, Node lhs, Node rhs) { super(loc, lhs, rhs); }
 
     @Override public String label() { return "Sar"; }
     @Override public String op() { return ">>"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if (t1 instanceof TypeInteger i0 &&
-            t2 instanceof TypeInteger i1) {
-            if( i0 == TypeInteger.ZERO )
-                return TypeInteger.ZERO;
-            if( i0.isConstant() && i1.isConstant() )
-                return TypeInteger.constant(i0.value()>>i1.value());
-            if( i1.isConstant() ) {
-                int log = (int)i1.value();
-                return TypeInteger.make(-1L<<(63-log),(1L<<(63-log))-1);
-            }
+    @Override long doOp( long x, long y ) { return x >> y; }
+    @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
+        if( y.isConstant() ) {
+            int log = (int)y.value();
+            return TypeInteger.make(-1L<<(63-log),(1L<<(63-log))-1);
         }
         return TypeInteger.BOT;
     }
@@ -42,7 +30,7 @@ public class SarNode extends LogicalNode {
 
         // TODO: x >> 3 >> (y ? 1 : 2) ==> x >> (y ? 4 : 5)
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new SarNode(_loc,lhs,rhs); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
index 8d3e3089..44f0bc05 100644
--- a/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/ScopeNode.java
@@ -32,7 +32,10 @@ public class ScopeNode extends Node {
     // Size of each nested lexical scope
     public final Ary<Integer> _lexSize;
 
-    // Lexical scope is one of normal Block, constructor or function
+    // Lexical scope is typed:
+    // - Block scope - basic block scoping
+    // - Constructor - struct type is defined, and here we give values to all fields
+    // - Function - out-of-scope lookups restricted to final constants
     public enum Kind { Block, Constructor, Function };
     public final Ary<Kind> _kinds;
 
@@ -56,7 +59,7 @@ public class ScopeNode extends Node {
         int j=1;
         for( int i=0; i<nIns(); i++ ) {
             if( j < _lexSize._len && i == _lexSize.at(j) ) { p.p("| "); j++; }
-            Var v = _vars.get(i);
+            Var v = _vars.at(i);
             p.p(v._type().print(new SB()));
             p.p(" ");
             if( v._final ) p.p("!");
@@ -76,6 +79,7 @@ public class ScopeNode extends Node {
 
     public Node ctrl() { return in(0); }
     public Node mem() { return in(lookup(MEM0)); }
+    public Var var(int i) { return _vars.at(i); }
 
     /**
      * The ctrl of a ScopeNode is always bound to the currently active
@@ -90,7 +94,7 @@ public class ScopeNode extends Node {
     public <N extends Node> N ctrl(N n) { return setDef(0,n); }
     public Node mem(Node n) { update(MEM0,n); return n; }
 
-    public void push(Kind kind) {
+    public void push( Kind kind ) {
         assert _lexSize._len==_kinds._len;
         _lexSize.push(_vars.size());
         _kinds  .push(kind);
@@ -99,11 +103,11 @@ public class ScopeNode extends Node {
     // Pop a lexical scope
     public void pop() {
         assert _lexSize._len==_kinds._len;
-        promote();
+        promote();              // Promote forward references to the next outer scope
         int n = _lexSize.pop();
         _kinds.pop();
-        popUntil(n);
-        _vars.setLen(n);
+        popUntil(n);            // Pop off inputs going out of scope
+        _vars.setLen(n);        // Pop off variables going out of scope
     }
 
 
@@ -112,7 +116,7 @@ public class ScopeNode extends Node {
     public void promote() {
         int n = _lexSize.last();
         for( int i=n; i<nIns(); i++ ) {
-            Var v = _vars.at(i);
+            Var v = var(i);
             if( !v.isFRef() ) continue;
             if( _lexSize._len==1 )
                 throw Parser.error("Undefined name '" + v._name + "'",v._loc);
@@ -134,7 +138,7 @@ public class ScopeNode extends Node {
         return false;
     }
 
-    public boolean inCon() { return _kinds.last() == Kind.Constructor; }
+    public boolean inConstructor() { return _kinds.last() == Kind.Constructor; }
 
     // Is v outside any current function scope?
     public boolean outOfFunction( Var v ) {
@@ -148,9 +152,9 @@ public class ScopeNode extends Node {
     // Find name in reverse, return an index into _vars or -1.  Linear scan
     // instead of hashtable, but probably doesn't matter until the scan
     // typically hits many dozens of variables.
-    int find( String name ) {
+    public int find( String name ) {
         for( int i=_vars.size()-1; i>=0; i-- )
-            if( _vars.at(i)._name.equals(name) )
+            if( var(i)._name.equals(name) )
                 return i;
         return -1;
     }
@@ -162,7 +166,7 @@ public class ScopeNode extends Node {
         assert _lexSize.isEmpty() || name.charAt(0)!='$' ; // Later scopes do not define memory
         if( _lexSize._len > 0 )
             for( int i=_vars.size()-1; i>=_lexSize.last(); i-- ) {
-                Var n = _vars.at(i);
+                Var n = var(i);
                 if( n._name.equals(name) ) {
                     if( !n.isFRef() ) return false;       // Double define
                     FRefNode fref = (FRefNode)in(n._idx); // Get forward ref
@@ -189,11 +193,11 @@ public class ScopeNode extends Node {
     public Var lookup( String name ) {
         int idx = find(name);
         // -1 is missed in all scopes, not found
-        return idx == -1 ? null : update(_vars.at(idx),null);
+        return idx == -1 ? null : update(var(idx),null);
     }
 
     /**
-     * If the name is present in any scope, then redefine else null
+     * Redefine an existing name
      *
      * @param name Name being redefined
      * @param n    The node to bind to the name
@@ -201,7 +205,7 @@ public class ScopeNode extends Node {
     public void update( String name, Node n ) {
         int idx = find(name);
         assert idx>=0;
-        update(_vars.at(idx),n);
+        update(var(idx),n);
     }
 
     public Var update( Var v, Node st ) {
@@ -215,7 +219,7 @@ public class ScopeNode extends Node {
                 // Set real Phi in the loop head
                 // The phi takes its one input (no backedge yet) from a recursive
                 // lookup, which might have insert a Phi in every loop nest.
-                : loop.setDef(v._idx,PhiNode.make(v._name, v.lazyGLB(), loop.ctrl(), loop.in(loop.update(v,null)._idx),null).peephole());
+                : loop.setDef(v._idx,PhiNode.make(v._name, v.type(), loop.ctrl(), loop.in(loop.update(v,null)._idx),null).peephole());
             setDef(v._idx,old);
         }
         assert !v._final || st==null || canInit(v);
@@ -281,7 +285,7 @@ public class ScopeNode extends Node {
             if( in(i) != that.in(i) ) { // No need for redundant Phis
                 // If we are in lazy phi mode we need to a lookup
                 // by name as it will trigger a phi creation
-                Var v = _vars.at(i);
+                Var v = var(i);
                 Node lhs = this.in(this.update(v,null));
                 Node rhs = that.in(that.update(v,null));
                 setDef(i, PhiNode.make(v._name, v.type(), r, lhs, rhs).peephole());
@@ -292,7 +296,7 @@ public class ScopeNode extends Node {
     // Forward refs are copied to the other side, "as if" they were there all along.
     public void balanceIf( ScopeNode scope ) {
         for( int i = nIns(); i < scope.nIns(); i++ ) {
-            Var n = scope._vars.at(i);
+            Var n = scope.var(i);
             if( n.isFRef() ) {  // RHS has forward refs
                 _vars.add(n);   // Copy to LHS
                 addDef(scope.in(i));
diff --git a/src/main/java/com/seaofnodes/simple/node/ShlNode.java b/src/main/java/com/seaofnodes/simple/node/ShlNode.java
index afd20062..e2951784 100644
--- a/src/main/java/com/seaofnodes/simple/node/ShlNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/ShlNode.java
@@ -3,25 +3,22 @@ package com.seaofnodes.simple.node;
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-import java.util.BitSet;
 
-public class ShlNode extends LogicalNode {
+public class ShlNode extends ArithNode {
     public ShlNode(Parser.Lexer loc, Node lhs, Node rhs) { super(loc, lhs, rhs); }
 
     @Override public String label() { return "Shl"; }
     @Override public String op() { return "<<"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if (t1 instanceof TypeInteger i0 &&
-            t2 instanceof TypeInteger i1 ) {
-            if( i0 == TypeInteger.ZERO )
-                return TypeInteger.ZERO;
-            if( i0.isConstant() && i1.isConstant() )
-                return TypeInteger.constant(i0.value()<<i1.value());
+    @Override long doOp( long x, long y ) { return x << y; }
+    @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
+        if( x == TypeInteger.ZERO )
+            return TypeInteger.ZERO;
+        if( y.isConstant() ) {
+            int shf = (int)y.value();
+            // If no overflow, shift endpoints
+            if( !(((x._min<<shf)>>shf) != x._min ||
+                  ((x._max<<shf)>>shf) != x._max ) )
+                    return TypeInteger.make(x._min<<shf,x._max<<shf);
         }
         return TypeInteger.BOT;
     }
@@ -45,7 +42,7 @@ public class ShlNode extends LogicalNode {
 
         // TODO: x << 3 << (y ? 1 : 2) ==> x << (y ? 4 : 5)
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new ShlNode(_loc,lhs,rhs); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/ShrNode.java b/src/main/java/com/seaofnodes/simple/node/ShrNode.java
index 587e1631..0023431f 100644
--- a/src/main/java/com/seaofnodes/simple/node/ShrNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/ShrNode.java
@@ -3,27 +3,15 @@ package com.seaofnodes.simple.node;
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-import java.util.BitSet;
 
-public class ShrNode extends LogicalNode {
+public class ShrNode extends ArithNode {
     public ShrNode(Parser.Lexer loc, Node lhs, Node rhs) { super(loc, lhs, rhs); }
 
     @Override public String label() { return "Shr"; }
     @Override public String op() { return ">>>"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if (t1 instanceof TypeInteger i0 &&
-            t2 instanceof TypeInteger i1 ) {
-            if( i0 == TypeInteger.ZERO )
-                return TypeInteger.ZERO;
-            if( i0.isConstant() && i1.isConstant() )
-                return TypeInteger.constant(i0.value()>>>i1.value());
-        }
-        return TypeInteger.BOT;
+    @Override long doOp( long x, long y ) { return x >>> y; }
+    @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
+        return x == TypeInteger.ZERO ? x : TypeInteger.BOT;
     }
 
     @Override
@@ -38,7 +26,7 @@ public class ShrNode extends LogicalNode {
 
         // TODO: x >>> 3 >>> (y ? 1 : 2) ==> x >>> (y ? 4 : 5)
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new ShrNode(_loc,lhs,rhs); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/StopNode.java b/src/main/java/com/seaofnodes/simple/node/StopNode.java
index c88dbf51..298c24a9 100644
--- a/src/main/java/com/seaofnodes/simple/node/StopNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/StopNode.java
@@ -24,11 +24,15 @@ public class StopNode extends CFGNode {
     @Override
     protected ExprPrinter<Node> _print1(ExprPrinter<Node> p) {
         // For the sake of many old tests, and single value prints as "return val"
-        if( ret()!=null ) return p.n(ret());
+        ReturnNode ret1 = ret();
+        if( ret1!=null ) return p.n(ret1);
         p.p("Stop[ ");
         for( Node ret : _inputs )
-            if( ret!=null )
-                p.n(ret).p(" ");
+            if( ret!=null ) {
+                String name = ((ReturnNode)ret).fun()._name;
+                if( name== null || !name.startsWith("sys.") )
+                    p.n(ret).p(" ");
+            }
         return p.p("]");
     }
 
@@ -38,7 +42,13 @@ public class StopNode extends CFGNode {
     // If a single Return, return it.
     // Otherwise, null because ambiguous.
     public ReturnNode ret() {
-        return nIns()==1 && in(0) instanceof ReturnNode ret ? ret : null;
+        Node ret1 = this;
+        for( Node ret : _inputs ) {
+            String name = ((ReturnNode)ret).fun()._name;
+            if( name==null || !name.startsWith("sys.") )
+                ret1 = ret1==this ? ((ReturnNode)ret) : null;
+        }
+        return ret1==this ? null : (ReturnNode)ret1;
     }
 
     @Override
@@ -50,7 +60,7 @@ public class StopNode extends CFGNode {
     public Node idealize() {
         int len = nIns();
         for( int i=0; i<nIns(); i++ )
-            if( ((ReturnNode)in(i)).fun().isDead() )
+            if( addDep(((ReturnNode)in(i)).fun()).isDead() )
                 delDef(i--);
         if( len != nIns() ) return this;
         return null;
diff --git a/src/main/java/com/seaofnodes/simple/node/StoreNode.java b/src/main/java/com/seaofnodes/simple/node/StoreNode.java
index a5b09663..ecda014b 100644
--- a/src/main/java/com/seaofnodes/simple/node/StoreNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/StoreNode.java
@@ -85,12 +85,23 @@ public class StoreNode extends MemOpNode {
             }
         }
 
-        // Store of zero after alloc
-        if( mem() instanceof ProjNode prj && prj.in(0) instanceof NewNode &&
-            prj.in(0)==ptr().in(0) &&  // Same NewNode memory & pointer
-            (val()._type==TypeInteger.ZERO || val()._type==Type.NIL ) )
-            return mem();
-
+        // Store will chop high order bits off; math to change those bits can be dropped.
+        if( val() instanceof SarNode shr &&
+            shr.in(1) instanceof ShlNode shl &&
+            shr.in(2)._type.isConstant() &&
+            shl.in(2)._type.isConstant() ) {
+            TypeInteger shrC = (TypeInteger) shr.in(2)._type;
+
+            // size of the thing that sign-extends
+            int base_size = (1 << shr.in(1)._type.log_size()) << 3;
+            int not_affected_bits = base_size - (int) shrC.value();
+            int store_size = (1 << log_size()) << 3;
+            // if the store is unrelated to the shift amount, then get rid of the shift
+            if( shl.in(2)._type == shr.in(2)._type && shrC.value() >= store_size && not_affected_bits >= store_size) {
+                setDef(4, shl.in(1));
+                return this;
+            }
+        }
         return null;
     }
 
@@ -154,8 +165,6 @@ public class StoreNode extends MemOpNode {
         TypeMemPtr tmp = (TypeMemPtr)ptr()._type;
         if( (tmp._ro || tmp._obj.field(_name)._final) && !_init )
             return Parser.error("Cannot modify final field '"+_name+"'",_loc);
-        //Type t = val()._type;
-        //return _init || t.isa(_declaredType) ? null : Parser.error("Cannot store "+t+" into field "+_declaredType+" "+_name,_loc);
         return null;
     }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/SubNode.java b/src/main/java/com/seaofnodes/simple/node/SubNode.java
index 9bf6d83e..2c4fed39 100644
--- a/src/main/java/com/seaofnodes/simple/node/SubNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/SubNode.java
@@ -1,35 +1,26 @@
 package com.seaofnodes.simple.node;
 
-
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
+import java.util.BitSet;
 
-public class SubNode extends Node {
+public class SubNode extends ArithNode {
     public SubNode(Node lhs, Node rhs) { super(null, lhs, rhs); }
 
     @Override public String label() { return "Sub"; }
+    @Override public String op() { return "-"; }
 
-    @Override protected String format() { return "(%1-%2)"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
+    @Override long doOp( long x, long y ) { return x - y; }
+    @Override TypeInteger doOp(TypeInteger x, TypeInteger y) {
         // Sub of same is 0
         if( in(1)==in(2) )
             return TypeInteger.ZERO;
-        if( t1 instanceof TypeInteger i1 &&
-            t2 instanceof TypeInteger i2 ) {
-            if (i1.isConstant() && i2.isConstant())
-                return TypeInteger.constant(i1.value()-i2.value());
-            // Fold ranges like {2-3} - {0-1} into {1-3}.
-            if( !AddNode.overflow(i1._min,-i2._max) &&
-                !AddNode.overflow(i1._max,-i2._min) &&
-                i2._min != Long.MIN_VALUE  )
-                return TypeInteger.make(i1._min-i2._max,i1._max-i2._min);
-        }
+        // Fold ranges like {2-3} - {0-1} into {1-3}.
+        if( !AddNode.overflow(x._min,-y._max) &&
+            !AddNode.overflow(x._max,-y._min) &&
+            y._min != Long.MIN_VALUE  )
+            return TypeInteger.make(x._min-y._max,x._max-y._min);
 
         return TypeInteger.BOT;
     }
@@ -55,7 +46,7 @@ public class SubNode extends Node {
         if( lhs instanceof MinusNode minus )
             return new MinusNode(new AddNode(minus.in(1),rhs).peephole());
 
-        return null;
+        return super.idealize();
     }
 
     @Override Node copy(Node lhs, Node rhs) { return new SubNode(lhs,rhs); }
diff --git a/src/main/java/com/seaofnodes/simple/node/XorNode.java b/src/main/java/com/seaofnodes/simple/node/XorNode.java
index 034e352a..75cea98e 100644
--- a/src/main/java/com/seaofnodes/simple/node/XorNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/XorNode.java
@@ -3,24 +3,14 @@ package com.seaofnodes.simple.node;
 import com.seaofnodes.simple.Parser;
 import com.seaofnodes.simple.type.Type;
 import com.seaofnodes.simple.type.TypeInteger;
-import java.util.BitSet;
 
-public class XorNode extends LogicalNode {
+public class XorNode extends ArithNode {
     public XorNode(Parser.Lexer loc, Node lhs, Node rhs) { super(loc, lhs, rhs); }
 
     @Override public String label() { return "Xor"; }
     @Override public String op() { return "^"; }
-
-    @Override
-    public Type compute() {
-        Type t1 = in(1)._type, t2 = in(2)._type;
-        if( t1.isHigh() || t2.isHigh() )
-            return TypeInteger.TOP;
-        if( t1 instanceof TypeInteger i0 &&
-            t2 instanceof TypeInteger i1 ) {
-            if( i0.isConstant() && i1.isConstant() )
-                return TypeInteger.constant(i0.value()^i1.value());
-        }
+    @Override long doOp( long x, long y ) { return x ^ y; }
+    @Override TypeInteger doOp( TypeInteger x, TypeInteger y ) {
         return TypeInteger.BOT;
     }
 
@@ -46,7 +36,7 @@ public class XorNode extends LogicalNode {
         Node phicon = AddNode.phiCon(this,true);
         if( phicon!=null ) return phicon;
 
-        return null;
+        return super.idealize();
     }
     @Override Node copy(Node lhs, Node rhs) { return new XorNode(_loc,lhs,rhs); }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallARM.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallARM.java
index 57d7ef7c..dd2d9e2c 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallARM.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallARM.java
@@ -9,13 +9,13 @@ import com.seaofnodes.simple.type.TypeFunPtr;
 public class CallARM extends CallNode implements MachNode, RIPRelSize {
     final TypeFunPtr _tfp;
     final String _name;
-
     CallARM(CallNode call, TypeFunPtr tfp) {
         super(call);
         _inputs.pop(); // Pop constant target
         assert tfp.isConstant();
         _tfp = tfp;
-        _name = CodeGen.CODE.link(tfp)._name;
+        FunNode fun = CodeGen.CODE.link(tfp);
+        _name = fun==null ? ((ExternNode)call.fptr())._extern : fun._name; // Can be null for extern calls
     }
 
     @Override public String op() { return "call"; }
@@ -24,9 +24,12 @@ public class CallARM extends CallNode implements MachNode, RIPRelSize {
     @Override public TypeFunPtr tfp() { return _tfp; }
     @Override public RegMask regmap(int i) { return arm.callInMask(_tfp,i,fun()._maxArgSlot); }
     @Override public RegMask outregmap() { return null; }
+    @Override public int nargs() { return nIns()-2; } // Minus control, memory, fptr
 
     @Override public void encoding( Encoding enc ) {
-        enc.relo(this);
+        FunNode fun = CodeGen.CODE.link(_tfp);
+        if( fun==null ) enc.external(this,_name);
+        else enc.relo(this);
         // BL
         enc.add4(Arm64.b(Arm64.OP_CALL,0)); // Target patched at link time
     }
@@ -40,7 +43,7 @@ public class CallARM extends CallNode implements MachNode, RIPRelSize {
     }
 
     @Override public void asm(CodeGen code, SB sb) {
-        sb.p(_name).p("  ");
+        sb.p(_name);
         for( int i=0; i<nargs(); i++ )
             sb.p(code.reg(arg(i+2))).p("  ");
         sb.unchar(2);
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallEndARM.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallEndARM.java
deleted file mode 100644
index b3c2f6c2..00000000
--- a/src/main/java/com/seaofnodes/simple/node/cpus/arm/CallEndARM.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package com.seaofnodes.simple.node.cpus.arm;
-
-import com.seaofnodes.simple.node.CallEndNode;
-import com.seaofnodes.simple.node.MachNode;
-
-public class CallEndARM extends CallEndNode implements MachNode {
-    CallEndARM( CallEndNode cend ) { super(cend); }
-}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/ExtendARM.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/ExtendARM.java
new file mode 100644
index 00000000..6fec7a77
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/arm/ExtendARM.java
@@ -0,0 +1,31 @@
+package com.seaofnodes.simple.node.cpus.arm;
+
+import com.seaofnodes.isa.Arm64;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.SB;
+
+// Convert a narrow C return register to Simple's full-width integer value.
+public class ExtendARM extends MachConcreteNode {
+    final int _bits;
+    final boolean _signed;
+    ExtendARM(ProjNode prj, TypeInteger ret) {
+        super(prj);
+        _inputs.set(0,null);
+        _inputs.add(new ProjARM(prj));
+        _bits = 8 << ret.log_size();
+        _signed = ret._min < 0;
+    }
+    @Override public String op() { return (_signed ? "sext" : "zext")+_bits; }
+    @Override public RegMask regmap(int i) { return arm.RMASK; }
+    @Override public RegMask outregmap() { return arm.WMASK; }
+    @Override public void encoding(Encoding enc) {
+        short dst = enc.reg(this), src = enc.reg(in(1));
+        // SBFM/UBFM aliases: sign/zero extend the low byte, short or int.
+        enc.add4(Arm64.imm_shift(_signed ? Arm64.OPI_ASR : Arm64.OPI_LSR,0,_bits-1,src,dst));
+    }
+    @Override public void asm(CodeGen code, SB sb) {
+        sb.p(code.reg(this)).p(" = ").p(code.reg(in(1)));
+    }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/FloatARM.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/FloatARM.java
index 6209397d..6bc2fe08 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/arm/FloatARM.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/arm/FloatARM.java
@@ -21,8 +21,6 @@ public class FloatARM extends ConstantNode implements MachNode, RIPRelSize {
     @Override public void encoding( Encoding enc ) {
         enc.largeConstant(this,_con,0,-1/*TODO: ARM-style ELF patching*/);
         short dst = (short)(enc.reg(this) - arm.D_OFFSET);
-        double d = ((TypeFloat)_con).value();
-        long x = Double.doubleToRawLongBits(d);
         enc.add4(Arm64.load_pc(Arm64.OPF_ARM, 0, dst));
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
index 1f2b6a37..720a14c1 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
@@ -5,7 +5,7 @@ import com.seaofnodes.simple.*;
 import com.seaofnodes.simple.codegen.*;
 import com.seaofnodes.simple.node.ConstantNode;
 import com.seaofnodes.simple.node.MachNode;
-import com.seaofnodes.simple.node.cpus.riscv.riscv;
+import com.seaofnodes.simple.node.Node;
 import com.seaofnodes.simple.type.TypeFunPtr;
 
 public class TFPARM extends ConstantNode implements MachNode, RIPRelSize {
@@ -26,21 +26,22 @@ public class TFPARM extends ConstantNode implements MachNode, RIPRelSize {
     }
 
     @Override public byte encSize(int delta) {
-        if( -(1L<<12) <= delta && delta < (1L<<12) ) return 4;
-        throw Utils.TODO();
+        return 8;
     }
 
     // Delta is from opcode start
     @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
         short rpc = enc.reg(this);
         if(opLen == 8 ) {
-            // opstart of add
-            int next = opStart + opLen;
+            // ARM encoding delta is from PC & 0xFFF
+            int target = opStart+delta;
+            int base = opStart & ~0xFFF;
+            delta = target-base;
             int adrp_delta = delta >> 12;
             // patch upper 20 bits via adrp
             enc.patch4(opStart, Arm64.adrp(1, adrp_delta & 0b11, 0b10000, adrp_delta >> 2, rpc));
             // low 12 bits via add
-            enc.patch4(next, Arm64.imm_inst_l(Arm64.OPI_ADD, delta & 0xfff, rpc));
+            enc.patch4(opStart+4, Arm64.imm_inst_l(Arm64.OPI_ADD, delta & 0xfff, rpc));
         } else {
             // should not happen as one instruction is 4 byte, and TFP arm encodes 2.
             throw Utils.TODO();
@@ -51,4 +52,5 @@ public class TFPARM extends ConstantNode implements MachNode, RIPRelSize {
         String reg = code.reg(this);
         _con.print(sb.p(reg).p(" #"));
     }
+    @Override public boolean eq(Node n) { return this==n; }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/TMPARM.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/TMPARM.java
new file mode 100644
index 00000000..adbaa8c2
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/arm/TMPARM.java
@@ -0,0 +1,54 @@
+package com.seaofnodes.simple.node.cpus.arm;
+
+import com.seaofnodes.isa.Arm64;
+import com.seaofnodes.simple.*;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.ConstantNode;
+import com.seaofnodes.simple.node.MachNode;
+import com.seaofnodes.simple.node.Node;
+import com.seaofnodes.simple.type.TypeMemPtr;
+
+public class TMPARM extends ConstantNode implements MachNode, RIPRelSize {
+    TMPARM( ConstantNode con ) { super(con); }
+    @Override public String op() { return "ldp"; }
+    @Override public RegMask regmap(int i) { return null; }
+    @Override public RegMask outregmap() { return arm.WMASK; }
+    @Override public boolean isClone() { return true; }
+    @Override public TMPARM copy() { return new TMPARM(this); }
+    @Override public void encoding( Encoding enc ) {
+        enc.largeConstant(this,((TypeMemPtr)_con)._obj,0,-1);
+        short dst = enc.reg(this);
+        // adrp    x0, 0
+        enc.add4(Arm64.adrp(1,0, Arm64.OP_ADRP, 0,dst));
+        // add     x0, x0, 0
+        arm.imm_inst(enc,Arm64.OPI_ADD,0, dst);
+    }
+
+    @Override public byte encSize(int delta) {
+        return 8;
+    }
+
+    // Delta is from opcode start
+    @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
+        short dst = enc.reg(this);
+        if(opLen == 8 ) {
+            // ARM encoding delta is from PC & 0xFFF
+            int target = opStart+delta;
+            int base = opStart & ~0xFFF;
+            delta = target-base;
+            int adrp_delta = delta >> 12;
+            // patch upper 20 bits via adrp
+            enc.patch4(opStart, Arm64.adrp(1, adrp_delta & 0b11, 0b10000, adrp_delta >> 2, dst));
+            // low 12 bits via add
+            enc.patch4(opStart+4, Arm64.imm_inst_l(Arm64.OPI_ADD, delta & 0xfff, dst));
+        } else {
+            throw Utils.TODO();
+        }
+    }
+
+    @Override public void asm(CodeGen code, SB sb) {
+        String reg = code.reg(this);
+        _con.print(sb.p(reg).p(" #"));
+    }
+    @Override public boolean eq(Node n) { return this==n; }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/arm/arm.java b/src/main/java/com/seaofnodes/simple/node/cpus/arm/arm.java
index 66a59fde..ddd9797b 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/arm/arm.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/arm/arm.java
@@ -224,6 +224,8 @@ public class arm extends Machine {
         if( idx==0 ) return CodeGen.CODE._rpcMask;
         if( idx==1 ) return null;
         // Count floats in signature up to index
+        if( idx-2 >= tfp.nargs() ) return null; // Anti-dependence
+        // Count floats in signature up to index
         int fcnt=0;
         for( int i=2; i<idx; i++ )
             if( tfp.arg(i-2) instanceof TypeFloat)
@@ -277,47 +279,47 @@ public class arm extends Machine {
     // Instruction selection
     @Override public Node instSelect(Node n ) {
         return switch( n ) {
-        case AddFNode addf  -> new AddFARM(addf);
-        case AddNode add    -> add(add);
-        case AndNode and    -> and(and);
-        case BoolNode bool  -> cmp(bool);
-        case CallNode call  -> call(call);
-        case CastNode cast  -> new CastARM(cast);
-        case CallEndNode cend -> new CallEndARM(cend);
-        case CProjNode c    -> new CProjNode(c);
-        case ConstantNode con -> con(con);
-        case DivFNode divf  -> new DivFARM(divf);
-        case DivNode div    -> new DivARM(div);
-        case FunNode fun    -> new FunARM(fun);
-        case IfNode iff     -> jmp(iff);
-        case LoadNode ld    -> ld(ld);
-        case MemMergeNode mem -> new MemMergeNode(mem);
-        case MinusNode neg  -> new NegARM(neg);
-        case MulFNode mulf  -> new MulFARM(mulf);
-        case MulNode mul    -> new MulARM(mul);
-        case NewNode nnn    -> new NewARM(nnn);
-        case NotNode not    -> new NotARM(not);
-        case OrNode or      -> or(or);
-        case ParmNode parm  -> new ParmARM(parm);
+        case AddFNode addf   -> new AddFARM(addf);
+        case AddNode add     -> add(add);
+        case AndNode and     -> and(and);
+        case BoolNode bool   -> cmp(bool);
+        case CallNode call   -> call(call);
+        case CastNode cast   -> new CastMach(cast);
+        case CallEndNode cend-> new CallEndMach(cend);
+        case CProjNode c     -> new CProjNode(c);
+        case ConstantNode con-> con(con);
+        case DivFNode divf   -> new DivFARM(divf);
+        case DivNode div     -> new DivARM(div);
+        case FunNode fun     -> new FunARM(fun);
+        case IfNode iff      -> jmp(iff);
+        case LoadNode ld     -> ld(ld);
+        case MemMergeNode mem-> new MemMergeNode(mem);
+        case MinusNode neg   -> new NegARM(neg);
+        case MulFNode mulf   -> new MulFARM(mulf);
+        case MulNode mul     -> new MulARM(mul);
+        case NewNode nnn     -> new NewARM(nnn);
+        case NotNode not     -> new NotARM(not);
+        case OrNode or       -> or(or);
+        case ParmNode parm   -> new ParmARM(parm);
         case BulkMemPhiNode phi -> new BulkMemPhiNode(phi);
         case MemPhiNode phi -> new MemPhiNode(phi);
-        case PhiNode phi    -> new PhiNode(phi);
-        case ProjNode prj   -> new ProjARM(prj);
-        case ReadOnlyNode read  -> new ReadOnlyNode(read);
-        case ReturnNode ret -> new RetARM(ret,ret.fun());
-        case SarNode sar    -> asr(sar);
-        case ShlNode shl    -> lsl(shl);
-        case ShrNode shr    -> lsr(shr);
+        case PhiNode phi     -> new PhiNode(phi);
+        case ProjNode prj    -> prj(prj);
+        case ReadOnlyNode read -> new ReadOnlyMach(read);
+        case ReturnNode ret  -> new RetARM(ret,ret.fun());
+        case SarNode sar     -> asr(sar);
+        case ShlNode shl     -> lsl(shl);
+        case ShrNode shr     -> lsr(shr);
         case StartNode start -> new StartNode(start);
-        case StopNode stop  -> new StopNode(stop);
-        case StoreNode st   -> st(st);
-        case SubFNode subf  -> new SubFARM(subf);
-        case SubNode sub    -> sub(sub);
-        case ToFloatNode tfn-> new I2F8ARM(tfn);
+        case StopNode stop   -> new StopNode(stop);
+        case StoreNode st    -> st(st);
+        case SubFNode subf   -> new SubFARM(subf);
+        case SubNode sub     -> sub(sub);
+        case ToFloatNode tfn -> new I2F8ARM(tfn);
         case ToIntegerNode cvt -> new F8ToIARM(cvt);
-        case XorNode xor    -> xor(xor);
+        case XorNode xor     -> xor(xor);
 
-        case LoopNode  loop  -> new LoopNode(loop);
+        case LoopNode loop   -> new LoopNode(loop);
         case RegionNode region-> new RegionNode(region);
         default -> throw Utils.TODO();
         };
@@ -365,13 +367,13 @@ public class arm extends Machine {
     private Node con( ConstantNode con ) {
         if( !con._con.isConstant() ) return new ConstantNode( con ); // Default unknown caller inputs
         return switch( con._con ) {
-            case TypeInteger ti  -> new IntARM(con);
-            case TypeFloat   tf  -> new FloatARM(con);
-            case TypeFunPtr  tfp -> new TFPARM(con);
-            case TypeMemPtr tmp -> new ConstantNode(con);
-            case TypeNil tn  -> throw Utils.TODO();
-            // TOP, BOTTOM, XCtrl, Ctrl, etc.  Never any executable code.
-            case Type t -> t==Type.NIL ? new IntARM(con) : new ConstantNode(con);
+        case TypeInteger ti -> new IntARM(con);
+        case TypeFloat   tf -> new FloatARM(con);
+        case TypeFunPtr tfp -> new TFPARM(con);
+        case TypeMemPtr tmp -> new TMPARM(con);
+        case TypeNil tn  -> throw Utils.TODO();
+        // TOP, BOTTOM, XCtrl, Ctrl, etc.  Never any executable code.
+        case Type t -> t==Type.NIL ? new IntARM(con) : new ConstantNode(con);
         };
     }
 
@@ -445,4 +447,9 @@ public class arm extends Machine {
         return mop;
     }
 
+    private Node prj(ProjNode prj) {
+        TypeInteger ret = cReturn(prj);
+        return ret==null ? new ProjARM(prj) : new ExtendARM(prj,ret);
+    }
+
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallEndRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallEndRISC.java
deleted file mode 100644
index 7df68e77..00000000
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallEndRISC.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package com.seaofnodes.simple.node.cpus.riscv;
-
-import com.seaofnodes.simple.node.CallEndNode;
-import com.seaofnodes.simple.node.MachNode;
-
-public class CallEndRISC extends CallEndNode implements MachNode {
-    CallEndRISC( CallEndNode cend ) { super(cend); }
-}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallRISC.java
index 2b3232c3..ff50a67f 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/CallRISC.java
@@ -14,23 +14,26 @@ public class CallRISC extends CallNode implements MachNode, RIPRelSize {
         assert tfp.isConstant();
         _inputs.pop(); // Pop constant target
         _tfp = tfp;
-        _name = CodeGen.CODE.link(tfp)._name;
+        FunNode fun = CodeGen.CODE.link(tfp);
+        _name = fun==null ? ((ExternNode)call.fptr())._extern : fun._name; // Can be null for extern calls
     }
 
     @Override public String op() { return "call"; }
     @Override public String label() { return op(); }
-    @Override public RegMask regmap(int i) {
-        return riscv.callInMask(_tfp,i,fun()._maxArgSlot);
-    }
-    @Override public RegMask outregmap() { return riscv.RPC_MASK; }
     @Override public String name() { return _name; }
     @Override public TypeFunPtr tfp() { return _tfp; }
+    @Override public RegMask regmap(int i) { return riscv.callInMask(_tfp,i,fun()._maxArgSlot); }
+    @Override public RegMask outregmap() { return riscv.RPC_MASK; }
+    @Override public int nargs() { return nIns()-2; } // Minus control, memory, fptr
 
     @Override public void encoding( Encoding enc ) {
         // Short form +/-4K:  beq r0,r0,imm12
         // Long form:  auipc rX,imm20/32; jal r0,[rX+imm12/32]
-        enc.relo(this);
-        enc.add4(RiscV.j_type(RiscV.OP_JAL, riscv.RPC, 0));
+        FunNode fun = CodeGen.CODE.link(_tfp);
+        if( fun==null ) enc.external(this,_name);
+        else enc.relo(this);
+        short rpc = enc.reg(this);
+        enc.add4(RiscV.j_type(RiscV.OP_JAL, rpc, 0));
     }
 
     // Delta is from opcode start
@@ -42,8 +45,9 @@ public class CallRISC extends CallNode implements MachNode, RIPRelSize {
 
     // Delta is from opcode start
     @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
+        short rpc = enc.reg(this);
         if( opLen==4 ) {
-            enc.patch4(opStart,RiscV.j_type(RiscV.OP_JAL, riscv.RPC, delta));
+            enc.patch4(opStart,RiscV.j_type(RiscV.OP_JAL, rpc, delta));
         } else {
             throw Utils.TODO();
         }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ExtendRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ExtendRISC.java
new file mode 100644
index 00000000..c2e93159
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ExtendRISC.java
@@ -0,0 +1,32 @@
+package com.seaofnodes.simple.node.cpus.riscv;
+
+import com.seaofnodes.isa.RiscV;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.SB;
+
+// Convert a narrow C return register to Simple's full-width integer value.
+public class ExtendRISC extends MachConcreteNode {
+    final int _bits;
+    final boolean _signed;
+    ExtendRISC(ProjNode prj, TypeInteger ret) {
+        super(prj);
+        _inputs.set(0,null);
+        _inputs.add(new ProjRISC(prj));
+        _bits = 8 << ret.log_size();
+        _signed = ret._min < 0;
+    }
+    @Override public String op() { return (_signed ? "sext" : "zext")+_bits; }
+    @Override public RegMask regmap(int i) { return riscv.RMASK; }
+    @Override public RegMask outregmap() { return riscv.WMASK; }
+    @Override public void encoding(Encoding enc) {
+        short dst = enc.reg(this), src = enc.reg(in(1));
+        int shift = 64-_bits;
+        enc.add4(RiscV.i_type(RiscV.OP_IMM,dst,1,src,shift));
+        enc.add4(RiscV.i_type(RiscV.OP_IMM,dst,5,dst,shift | (_signed ? 0x400 : 0)));
+    }
+    @Override public void asm(CodeGen code, SB sb) {
+        sb.p(code.reg(this)).p(" = ").p(code.reg(in(1)));
+    }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/FltRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/FltRISC.java
index 9f6dec78..3dbb40d1 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/FltRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/FltRISC.java
@@ -17,7 +17,7 @@ public class FltRISC extends ConstantNode implements MachNode, RIPRelSize {
     @Override public FltRISC copy() { return new FltRISC(this); }
 
     @Override public void encoding( Encoding enc ) {
-        enc.largeConstant(this,_con, 0, -1/*TODO: RISC5 style patching*/);
+        enc.largeConstant(this,_con, 0, -1);
         short dst = (short)(enc.reg(this) - riscv.F_OFFSET);
         short tmp = (short)riscv.T6;
         // AUIPC dst,#hi20_constant_pool
@@ -28,7 +28,6 @@ public class FltRISC extends ConstantNode implements MachNode, RIPRelSize {
     @Override public RegMask killmap() { return new RegMask(riscv.T6); }
 
     // Delta is from opcode start.
-    // TODO: always size 8?
     @Override public byte encSize(int delta) { return 8;  }
 
     // Delta is from opcode start
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ImmRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ImmRISC.java
index dd41589c..ceea98e3 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ImmRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/ImmRISC.java
@@ -42,8 +42,7 @@ abstract public class ImmRISC extends MachConcreteNode implements MachNode {
     @Override public void encoding( Encoding enc ) {
         short dst = enc.reg(this );
         short src = enc.reg(in(1));
-        int body = RiscV.i_type(opcode(), dst, func3(), src, _imm12 & 0xFFF);
-        enc.add4(body);
+        enc.add4(RiscV.i_type(opcode(), dst, func3(), src, _imm12 & 0xFFF));
     }
 
     // General form: "addi  rd = rs1 + imm"
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/Int8RISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/Int8RISC.java
new file mode 100644
index 00000000..fabb3b9d
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/Int8RISC.java
@@ -0,0 +1,48 @@
+package com.seaofnodes.simple.node.cpus.riscv;
+
+import com.seaofnodes.isa.RiscV;
+import com.seaofnodes.simple.node.ConstantNode;
+
+import com.seaofnodes.simple.*;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.MachNode;
+
+// Special instruction for loading 8 byte constants from the constant pool.
+
+public class Int8RISC extends ConstantNode implements MachNode, RIPRelSize {
+    public Int8RISC(ConstantNode con) { super(con); }
+
+    @Override public String op() { return "ld8"; }
+    @Override public RegMask regmap(int i) { return null; }
+    @Override public RegMask outregmap() { return riscv.WMASK; }
+    @Override public boolean isClone() { return true; }
+    @Override public Int8RISC copy() { return new Int8RISC(this); }
+
+    @Override public byte encSize(int delta) { return 8;  }
+
+    @Override public void encoding( Encoding enc ) {
+        short dst  = enc.reg(this);
+        short tmp = (short)riscv.T6;
+        enc.largeConstant(this,_con, 0, -1);
+        // AUIPC dst,#hi20_constant_pool
+        enc.add4(RiscV.u_type(RiscV.OP_AUIPC, tmp, 0));
+        // Load dst,[dst+#low12_constant_pool]
+        enc.add4(RiscV.i_type(RiscV.OP_LOAD, dst, 0b11, tmp, 0));
+    }
+    @Override public RegMask killmap() { return new RegMask(riscv.T6); }
+
+    // Delta is from opcode start
+    @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
+        short dst = enc.reg(this);
+        short tmp = (short)riscv.T6;
+        // AUIPC dst,#hi20_constant_pool
+        enc.patch4(opStart  , RiscV.u_type(RiscV.OP_AUIPC, tmp, delta>>12));
+        // Load dst,[dst+#low12_constant_pool]
+        enc.patch4(opStart+4, RiscV.i_type(RiscV.OP_LOAD, dst, 0b11, tmp, delta & 0xFFF));
+    }
+
+    @Override public void asm(CodeGen code, SB sb) {
+        _con.print(sb.p(code.reg(this)).p(" = #"));
+    }
+
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/LUI.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/LUI.java
index 596e11cd..deaa3b59 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/LUI.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/LUI.java
@@ -11,7 +11,7 @@ import com.seaofnodes.simple.type.TypeInteger;
 public class LUI extends ConstantNode implements MachNode {
     public LUI( int imm20 ) {
         super(TypeInteger.constant(imm20));
-        assert riscv.imm20Exact((TypeInteger)_con);
+        assert (imm20 & 0xFFF)==0;
     }
     @Override public RegMask regmap(int i) { return null; }
     @Override public RegMask outregmap() { return riscv.WMASK; }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/MemOpRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/MemOpRISC.java
index 41ab37be..c2025a3d 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/MemOpRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/MemOpRISC.java
@@ -36,8 +36,9 @@ public abstract class MemOpRISC extends MemOpNode implements MachNode {
         if(this instanceof StoreRISC) {
             if( _declaredType == TypeInteger. I8 || _declaredType == TypeInteger.U8  || _declaredType == TypeInteger.BOOL) func3=0; //   SB
             if( _declaredType == TypeInteger.I16 || _declaredType == TypeInteger.U16 ) func3=1; // SH
-            if( _declaredType == TypeInteger.I32 || _declaredType == TypeInteger.U32 || _declaredType instanceof TypeMemPtr) func3=2; //  SW
-            if( _declaredType == TypeInteger.BOT ) func3=3; //   SD
+            if( _declaredType == TypeInteger.I32 || _declaredType == TypeInteger.U32 ) func3=2; //  SW
+            if( _declaredType instanceof TypeMemPtr) func3=3; //  SD
+            if( _declaredType == TypeInteger.BOT   ) func3=3; //   SD
             if( func3 == -1 ) throw Utils.TODO();
             return func3;
         }
@@ -51,9 +52,10 @@ public abstract class MemOpRISC extends MemOpNode implements MachNode {
         if( _declaredType == TypeInteger.U32 ) func3=6; // LWU
 
         // float
-        if(_declaredType == TypeFloat.F32) func3 = 2; // fLW   fSW
-        if(_declaredType == TypeFloat.F64) func3 = 3; // fLD   fSD
-        if( _declaredType instanceof TypeMemPtr ) func3=3; // 8 byte pointers
+        if( _declaredType == TypeFloat.F32) func3 = 2; // fLW   fSW
+        if( _declaredType == TypeFloat.F64) func3 = 3; // fLD   fSD
+
+        if( _declaredType instanceof TypeMemPtr) func3 = 3; // 8 byte pointers (pick ld)
         if( func3 == -1 ) throw Utils.TODO();
         return func3;
     }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/SraIRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/SraIRISC.java
index 49b1cad9..48171483 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/SraIRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/SraIRISC.java
@@ -5,7 +5,9 @@ import com.seaofnodes.simple.Utils;
 import com.seaofnodes.simple.node.Node;
 
 public class SraIRISC extends ImmRISC {
-    public SraIRISC( Node and, int imm) { super(and,imm); }
+    public SraIRISC( Node and, int imm) {
+        super(and,imm | (0x20 << 5));
+    }
     @Override int opcode() {  return RiscV.OP_IMM; }
     @Override int func3() {  return 5;}
     @Override public String glabel() { return ">>"; }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/StoreRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/StoreRISC.java
index 3cb7cc2d..03e06f83 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/StoreRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/StoreRISC.java
@@ -27,7 +27,9 @@ public class StoreRISC extends MemOpRISC {
         if( i==1 ) return null; // mem
         if( i==2 ) return riscv.RMASK; // ptr
         // 2 - index
-        if( i==4 ) return _sz >= '4' ? riscv.MEM_MASK : riscv.RMASK; // No byte/short FP stores
+        if( i==4 ) return _sz >= '4'
+                       ? riscv.MEM_MASK   // Word/dword value in GPR or FPR
+                       : riscv.RMASK;     // Byte/short stores require a GPR
         return null; // Anti-dependence
     }
     @Override public RegMask outregmap() { return null; }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java
index 1d3c5920..d7da5ba1 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TFPRISC.java
@@ -5,6 +5,7 @@ import com.seaofnodes.simple.*;
 import com.seaofnodes.simple.codegen.*;
 import com.seaofnodes.simple.node.ConstantNode;
 import com.seaofnodes.simple.node.MachNode;
+import com.seaofnodes.simple.node.Node;
 import com.seaofnodes.simple.type.TypeFunPtr;
 
 public class TFPRISC extends ConstantNode implements MachNode, RIPRelSize {
@@ -20,11 +21,9 @@ public class TFPRISC extends ConstantNode implements MachNode, RIPRelSize {
         short dst = enc.reg(this);
         TypeFunPtr tfp = (TypeFunPtr)_con;
         // auipc  t0,0
-        int auipc = RiscV.u_type(RiscV.OP_AUIPC, dst, 0);
+        enc.add4(RiscV.u_type(RiscV.OP_AUIPC, dst, 0));
         // addi   t1,t0 + #0
-        int addi = RiscV.i_type(RiscV.OP_IMM, dst, 0, dst, 0);
-        enc.add4(auipc);
-        enc.add4(addi);
+        enc.add4(RiscV.i_type(RiscV.OP_IMM, dst, 0, dst, 0));
     }
 
     @Override public byte encSize(int delta) { return 8; }
@@ -45,5 +44,5 @@ public class TFPRISC extends ConstantNode implements MachNode, RIPRelSize {
     @Override public void asm(CodeGen code, SB sb) {
         _con.print(sb.p(code.reg(this)).p(" #"));
     }
-
+    @Override public boolean eq(Node n) { return this==n; }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TMPRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TMPRISC.java
new file mode 100644
index 00000000..46b8aace
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/TMPRISC.java
@@ -0,0 +1,42 @@
+package com.seaofnodes.simple.node.cpus.riscv;
+
+import com.seaofnodes.isa.RiscV;
+import com.seaofnodes.simple.*;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.ConstantNode;
+import com.seaofnodes.simple.node.MachNode;
+import com.seaofnodes.simple.node.Node;
+import com.seaofnodes.simple.type.TypeMemPtr;
+
+public class TMPRISC extends ConstantNode implements MachNode, RIPRelSize {
+    TMPRISC(ConstantNode con) { super(con); }
+    @Override public String op() { return "ldp"; }
+    @Override public RegMask regmap(int i) { return null; }
+    @Override public RegMask outregmap() { return riscv.WMASK; }
+    @Override public boolean isClone() { return true; }
+    @Override public TMPRISC copy() { return new TMPRISC(this); }
+    @Override public void encoding( Encoding enc ) {
+        enc.largeConstant(this,((TypeMemPtr)_con)._obj,0,-1);
+        short dst = enc.reg(this);
+        // AUIPC dst,#hi20_constant_pool
+        enc.add4(RiscV.u_type(RiscV.OP_AUIPC, dst, 0));
+        // addi dst,[dst+#low12_constant_pool]
+        enc.add4(RiscV.i_type(RiscV.OP_IMM, dst, 0, dst, 0));
+    }
+
+    @Override public byte encSize(int delta) { return 8; }
+
+    // Delta is from opcode start
+    @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
+        short dst = enc.reg(this);
+        // Round the high part because ADDI's low 12 bits are signed.
+        enc.patch4(opStart  , RiscV.u_type(RiscV.OP_AUIPC, dst, (delta+0x800)>>12));
+        // ADDI dst,dst,#low12_constant_pool
+        enc.patch4(opStart+4, RiscV.i_type(RiscV.OP_IMM, dst, 0, dst, delta & 0xFFF));
+    }
+
+    @Override public void asm(CodeGen code, SB sb) {
+        _con.print(sb.p(code.reg(this)).p(" #"));
+    }
+    @Override public boolean eq(Node n) { return this==n; }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/XorIRISC.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/XorIRISC.java
index df96d10b..ebdf9fa8 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/XorIRISC.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/XorIRISC.java
@@ -6,6 +6,7 @@ import com.seaofnodes.simple.node.Node;
 
 public class XorIRISC extends ImmRISC {
     public XorIRISC( Node and, int imm) { super(and,imm); }
+    public XorIRISC( Node and, int imm, boolean pop) { super(and,imm,pop); }
     @Override int opcode() {  return RiscV.OP_IMM; }
     @Override int func3() {  return 4; }
     @Override public String glabel() { return "^"; }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/riscv.java b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/riscv.java
index 335347e9..f2d1e0b9 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/riscv/riscv.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/riscv/riscv.java
@@ -137,6 +137,7 @@ public class riscv extends Machine {
     static RegMask callInMask( TypeFunPtr tfp, int idx, int maxArgSlot ) {
         if( idx==0 ) return RPC_MASK;
         if( idx==1 ) return null;
+        if( idx-2 >= tfp.nargs() ) return null; // Anti-dependence
         // Count floats in signature up to index
         int fcnt=0;
         for( int i=2; i<idx; i++ )
@@ -197,7 +198,7 @@ public class riscv extends Machine {
         // shift left 32 to clear out the upper 32 bits.
         // shift right SIGNED to sign-extend upper 32 bits; then shift 12 more to clear out lower 12 bits.
         // shift left 12 to re-center the bits.
-        return ti.isConstant() && (((ti.value()<<32)>>>44)<<12) == ti.value();
+        return ti.isConstant() && (((ti.value()<<32)>>44)<<12) == ti.value();
     }
 
     @Override public Node instSelect( Node n ) {
@@ -207,8 +208,8 @@ public class riscv extends Machine {
         case AndNode      and -> and(and);
         case BoolNode    bool -> cmp(bool);
         case CallNode    call -> call(call);
-        case CastNode   cast  -> new CastRISC(cast);
-        case CallEndNode cend -> new CallEndRISC(cend);
+        case CastNode   cast  -> new CastMach(cast);
+        case CallEndNode cend -> new CallEndMach(cend);
         case CProjNode      c -> new CProjNode(c);
         case ConstantNode con -> con(con);
         case DivFNode    divf -> new DivFRISC(divf);
@@ -228,7 +229,7 @@ public class riscv extends Machine {
         case MemPhiNode phi -> new MemPhiNode(phi);
         case PhiNode      phi -> new PhiNode(phi);
         case ProjNode     prj -> prj(prj);
-        case ReadOnlyNode read-> new ReadOnlyNode(read);
+        case ReadOnlyNode read-> new ReadOnlyMach(read);
         case ReturnNode   ret -> new RetRISC(ret, ret.fun());
         case SarNode      sar -> sra(sar);
         case ShlNode      shl -> sll(shl);
@@ -302,7 +303,7 @@ public class riscv extends Machine {
             ? new SetIRISC(bool, (int)ti.value(),false)
             : new  SetRISC(bool, false);
         // x <= y - flip and negate; !(y < x); `slt tmp=y,x; xori dst=tmp,#1`
-        case "<=" -> new XorIRISC(new SetRISC(bool.swap12(), false),1);
+        case "<=" -> new XorIRISC(new SetRISC(bool.swap12(), false),1,false);
         // x == y - sub and vs0 == `sub tmp=x-y; sltu dst=tmp,#1`
         case "==" -> new SetIRISC(new SubRISC(bool),1,true,false);
         default -> throw Utils.TODO();
@@ -325,12 +326,12 @@ public class riscv extends Machine {
             }
             // Need more complex sequence for larger constants... or a load
             // from a constant pool, which does not need an extra register
-            throw Utils.TODO();
+            yield new Int8RISC(con);
         }
         // Load from constant pool
         case TypeFloat   tf  -> new FltRISC(con);
         case TypeFunPtr  tfp -> new TFPRISC(con);
-        case TypeMemPtr  tmp -> throw Utils.TODO();
+        case TypeMemPtr  tmp -> new TMPRISC(con);
         case TypeNil     tn  -> throw Utils.TODO();
         // TOP, BOTTOM, XCtrl, Ctrl, etc.  Never any executable code.
         case Type t -> t==Type.NIL ? new IntRISC(con) : new ConstantNode(con);
@@ -391,6 +392,8 @@ public class riscv extends Machine {
     }
 
     private Node prj(ProjNode prj) {
+        TypeInteger ret = cReturn(prj);
+        if( ret!=null ) return new ExtendRISC(prj,ret);
         return new ProjRISC(prj);
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/AddIX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/AddIX86.java
index 569be754..c55f975c 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/AddIX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/AddIX86.java
@@ -1,5 +1,9 @@
 package com.seaofnodes.simple.node.cpus.x86_64_v2;
 
+import com.seaofnodes.isa.X86;
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.Utils;
+import com.seaofnodes.simple.codegen.Encoding;
 import com.seaofnodes.simple.node.Node;
 
 public class AddIX86 extends ImmX86 {
@@ -10,4 +14,10 @@ public class AddIX86 extends ImmX86 {
     @Override public String glabel() { return "+"; }
     @Override int opcode() { return 0x81; }
     @Override int mod() { return 0; }
+    @Override public final void encoding( Encoding enc ) {
+        if( _imm== 1 || _imm== -1 ) {
+            short dst = enc.reg(this); // Also src1
+            X86.unary(enc,0xFF,_imm==1 ? 0 : 1,dst);
+        } else super.encoding(enc);
+    }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallEndX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallEndX86.java
deleted file mode 100644
index ce8b993f..00000000
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallEndX86.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package com.seaofnodes.simple.node.cpus.x86_64_v2;
-
-import com.seaofnodes.simple.node.CallEndNode;
-import com.seaofnodes.simple.node.MachNode;
-
-public class CallEndX86 extends CallEndNode implements MachNode {
-    CallEndX86( CallEndNode cend ) { super(cend); }
-}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallX86.java
index c97037e2..3d450040 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CallX86.java
@@ -1,9 +1,9 @@
 package com.seaofnodes.simple.node.cpus.x86_64_v2;
 
+import com.seaofnodes.isa.X86;
 import com.seaofnodes.simple.SB;
 import com.seaofnodes.simple.codegen.*;
-import com.seaofnodes.simple.node.CallNode;
-import com.seaofnodes.simple.node.MachNode;
+import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.type.TypeFunPtr;
 
 public class CallX86 extends CallNode implements MachNode, RIPRelSize {
@@ -14,7 +14,8 @@ public class CallX86 extends CallNode implements MachNode, RIPRelSize {
         _inputs.pop(); // Pop constant target
         assert tfp.isConstant();
         _tfp = tfp;
-        _name = CodeGen.CODE.link(tfp)._name;
+        FunNode fun = CodeGen.CODE.link(tfp);
+        _name = fun==null ? ((ExternNode)call.fptr())._extern : fun._name; // Can be null for extern calls
     }
     @Override public String op() { return "call"; }
     @Override public String label() { return op(); }
@@ -25,7 +26,10 @@ public class CallX86 extends CallNode implements MachNode, RIPRelSize {
     @Override public int nargs() { return nIns()-2; } // Minus control, memory, fptr
 
     @Override public void encoding( Encoding enc ) {
-        enc.relo(this).add1(0xe8).add4(0);
+        FunNode fun = CodeGen.CODE.link(_tfp);
+        if( fun==null ) enc.external(this,_name);
+        else enc.relo(this);
+        X86.call(enc);
     }
 
     // Delta is from opcode start, but X86 measures from the end of the 5-byte encoding
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CastX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CastX86.java
deleted file mode 100644
index 9537cfb3..00000000
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CastX86.java
+++ /dev/null
@@ -1,16 +0,0 @@
-package com.seaofnodes.simple.node.cpus.x86_64_v2;
-
-import com.seaofnodes.simple.SB;
-import com.seaofnodes.simple.codegen.*;
-import com.seaofnodes.simple.node.CastNode;
-import com.seaofnodes.simple.node.MachNode;
-
-public class CastX86 extends CastNode implements MachNode {
-    CastX86( CastNode cast ) { super(cast); }
-    @Override public String op() { return label(); }
-    @Override public RegMask regmap(int i) { assert i==1; return RegMask.FULL; }
-    @Override public RegMask outregmap() { return RegMask.FULL; }
-    @Override public int twoAddress( ) { return 1; }
-    @Override public void encoding( Encoding enc ) { }
-    @Override public void asm(CodeGen code, SB sb) { _t.print(sb.p(code.reg(in(1))).p(" isa ")); }
-}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpMemX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpMemX86.java
index bf8f1631..942400f4 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpMemX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpMemX86.java
@@ -12,7 +12,7 @@ public class CmpMemX86 extends MemOpX86 {
     CmpMemX86( BoolNode bool, LoadNode ld, Node base, Node idx, int off, int scale, int imm, Node val, boolean swap ) {
         super(bool,ld, base, idx, off, scale, imm, val );
         _swap = swap;
-        assert !_swap || val() == null || bool.op()=="==" || bool.op()=="!="; // Cannot swap with immediate
+        assert !_swap || val() != null || bool.op()=="==" || bool.op()=="!="; // Cannot swap with immediate
     }
     @Override public String op() { return ((val()==null && _imm==0) ? "test" : "cmp") + _sz; }
     @Override public RegMask outregmap() { return x86_64_v2.FLAGS_MASK; }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpX86.java
index e3cbe75f..27246db5 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/CmpX86.java
@@ -10,6 +10,12 @@ public class CmpX86 extends MachConcreteNode implements MachNode {
     @Override public String op() { return "cmp"; }
     @Override public RegMask regmap(int i) { return x86_64_v2.RMASK; }
     @Override public RegMask outregmap() { return x86_64_v2.FLAGS_MASK; }
+    // This one is marginal: cloning a Cmp[reg,reg] means stretching the
+    // lifetimes of 2 normal registers in exchange for shortening a flags
+    // register lifetime.  Spilling flags is (probably) relatively expensive
+    // compared to some normal registers - and those normal registers might not
+    // be spilling!
+    @Override public boolean isClone() { return true; }
 
     @Override public void encoding( Encoding enc ) {
         X86.reg(enc,0x3B,enc.reg(in(1)),enc.reg(in(2)));
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/DivX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/DivX86.java
index e61f576c..5d061ae1 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/DivX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/DivX86.java
@@ -9,7 +9,7 @@ public class DivX86 extends MachConcreteNode implements MachNode {
     DivX86( Node div ) { super(div); }
     @Override public String op() { return "div"; }
     @Override public RegMask regmap(int i) {
-        return (i==1) ? x86_64_v2.RAX_MASK : x86_64_v2.RMASK;
+        return (i==1) ? x86_64_v2.RAX_MASK : x86_64_v2.DIV_MASK;
     }
     @Override public RegMask outregmap() { return x86_64_v2.RAX_MASK; }
     @Override public RegMask killmap() { return x86_64_v2.RDX_MASK; }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ExtendX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ExtendX86.java
new file mode 100644
index 00000000..bd40bae7
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ExtendX86.java
@@ -0,0 +1,29 @@
+package com.seaofnodes.simple.node.cpus.x86_64_v2;
+
+import com.seaofnodes.isa.X86;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.SB;
+
+// Convert a narrow C return register to Simple's full-width integer value.
+public class ExtendX86 extends MachConcreteNode {
+    final int _bits;
+    final boolean _signed;
+    ExtendX86(ProjNode prj, TypeInteger ret) {
+        super(prj);
+        _inputs.set(0,null);
+        _inputs.add(new ProjX86(prj));
+        _bits = 8 << ret.log_size();
+        _signed = ret._min < 0;
+    }
+    @Override public String op() { return (_signed ? "sext" : "zext")+_bits; }
+    @Override public RegMask regmap(int i) { return x86_64_v2.RMASK; }
+    @Override public RegMask outregmap() { return x86_64_v2.WMASK; }
+    @Override public void encoding(Encoding enc) {
+        X86.extend(enc,_bits,_signed,enc.reg(this),enc.reg(in(1)));
+    }
+    @Override public void asm(CodeGen code, SB sb) {
+        sb.p(code.reg(this)).p(" = ").p(code.reg(in(1)));
+    }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ImmX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ImmX86.java
index b87e7f47..08c9b4c9 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ImmX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/ImmX86.java
@@ -16,11 +16,12 @@ public abstract class ImmX86 extends MachConcreteNode implements MachNode {
     @Override public RegMask regmap(int i) { return x86_64_v2.RMASK; }
     @Override public RegMask outregmap() { return x86_64_v2.WMASK; }
     @Override public int twoAddress() { return 1; }
+    @Override public RegMask killmap() { return x86_64_v2.FLAGS_MASK; }
 
     abstract int opcode();
     abstract int mod();
 
-    @Override public final void encoding( Encoding enc ) {
+    @Override public void encoding( Encoding enc ) {
         X86.imm(enc,opcode(),mod(),enc.reg(this),_imm);
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MemAddX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MemAddX86.java
index 6c7ecbbc..22a1a7ae 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MemAddX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MemAddX86.java
@@ -14,6 +14,7 @@ public class MemAddX86 extends MemOpX86 {
     }
     // Register mask allowed as a result.  0 for no register.
     @Override public RegMask outregmap() { return null; }
+    @Override public RegMask killmap() { return x86_64_v2.FLAGS_MASK; }
     @Override public void encoding( Encoding enc ) {
         X86.addMem(enc,enc.reg(val()),_imm,enc.reg(ptr()),enc.reg(idx()),_off,_scale);
     }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java
index 2c1ce261..4a7e24d0 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java
@@ -7,8 +7,8 @@ import com.seaofnodes.simple.codegen.*;
 
 public class MulIX86 extends MachConcreteNode implements MachNode {
     final int _imm;
-    MulIX86( Node mul, int imm ) {
-        super(mul);
+    MulIX86( Node add, int imm ) {
+        super(add);
         _inputs.pop();          // Pop the constant input
         _imm = imm;             // Record the constant
     }
@@ -16,14 +16,11 @@ public class MulIX86 extends MachConcreteNode implements MachNode {
     @Override public String glabel() { return "*"; }
     @Override public RegMask regmap(int i) { return x86_64_v2.RMASK; }
     @Override public RegMask outregmap() { return x86_64_v2.WMASK; }
-    // Retain Chapter 21's allocation contract: output is also input #1.
-    @Override public int twoAddress() { return 1; }
-
-    // IMUL encodes a destination register, unlike ImmX86's opcode extension.
+    // Rare 3-address form
     @Override public final void encoding( Encoding enc ) {
         X86.imul(enc,enc.reg(this),enc.reg(in(1)),_imm);
     }
-    // General form: "muli  dst = src * #imm"
+    // General form: "addi  dst += #imm"
     @Override public void asm(CodeGen code, SB sb) {
         sb.p(code.reg(this)).p(" = ").p(code.reg(in(1))).p(" * #").p(_imm);
     }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RegX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RegX86.java
index 8dc749ee..50c8e974 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RegX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RegX86.java
@@ -9,6 +9,7 @@ public abstract class RegX86 extends MachConcreteNode {
     RegX86( Node add ) { super(add); }
     @Override public RegMask regmap(int i) { return x86_64_v2.RMASK; }
     @Override public RegMask outregmap() { return x86_64_v2.WMASK; }
+    @Override public RegMask killmap() { return x86_64_v2.FLAGS_MASK; }
     @Override public int twoAddress() { return 1; }
     abstract int opcode();
     @Override public void encoding( Encoding enc ) {
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TFPX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TFPX86.java
index d0c6157c..8723af91 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TFPX86.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TFPX86.java
@@ -49,4 +49,5 @@ public class TFPX86 extends ConstantNode implements MachNode, RIPRelSize {
         else
             _con.print(sb.p(reg).p(" = #"));
     }
+    @Override public boolean eq(Node n) { return this==n; }
 }
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TMPX86.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TMPX86.java
new file mode 100644
index 00000000..027b2e01
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/TMPX86.java
@@ -0,0 +1,36 @@
+package com.seaofnodes.simple.node.cpus.x86_64_v2;
+
+import com.seaofnodes.isa.X86;
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeMemPtr;
+
+public class TMPX86 extends ConstantNode implements MachNode, RIPRelSize{
+    TMPX86(ConstantNode con ) { super(con); }
+    @Override public String op() { return "ldp"; }
+    @Override public RegMask regmap(int i) { return null; }
+    @Override public RegMask outregmap() { return x86_64_v2.WMASK; }
+    @Override public boolean isClone() { return true; }
+    @Override public Node copy() { return new TMPX86(this); }
+
+    @Override public void encoding( Encoding enc ) {
+        short dst = enc.reg(this);
+        X86.rexF(dst, 0, 0, true, enc);
+        enc.add1(0x8D).add1(X86.modrm(X86.MOD.INDIRECT, dst, 0b101)).add4(0);
+        enc.largeConstant(this,((TypeMemPtr)_con)._obj,7-4,2/*ELF encoding PC32*/);
+    }
+
+    // Delta is from opcode start
+    @Override public byte encSize(int delta) { return (byte)7; }
+
+    // Delta is from opcode start
+    @Override public void patch( Encoding enc, int opStart, int opLen, int delta ) {
+        enc.patch4(opStart+opLen-4,delta-opLen);
+    }
+
+    @Override public void asm(CodeGen code, SB sb) {
+        _con.print(sb.p(code.reg(this)).p(" = #"));
+    }
+    @Override public boolean eq(Node n) { return this==n; }
+}
diff --git a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/x86_64_v2.java b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/x86_64_v2.java
index 1b7cf775..7ddd17d4 100644
--- a/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/x86_64_v2.java
+++ b/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/x86_64_v2.java
@@ -43,6 +43,8 @@ public class x86_64_v2 extends Machine {
     static RegMask XMASK = new RegMask(FP_BITS);
     static RegMask FLAGS_MASK = new RegMask(FLAGS);
     static RegMask RPC_MASK = new RegMask(RPC);
+    // Divide mask: exclude RDX:RAX
+    static RegMask DIV_MASK = new RegMask(RD_BITS & ~(1L<<RAX) & ~(1L<<RDX));
 
     static final long SPILLS = -(1L << MAX_REG);
     static final RegMask SPLIT_MASK = new RegMask(WR_BITS | FP_BITS /* | (1L<<FLAGS)*/ | SPILLS, -1L );
@@ -61,7 +63,7 @@ public class x86_64_v2 extends Machine {
     public static RegMask XMM0_MASK = new RegMask(XMM0);
 
     // Encoding
-    public static int REX = 0x40;
+    public static int REX    = 0x40;
     public static int REX_W  = 0x48;
     public static int REX_WR = 0x4C;
     public static int REX_WRB= 0x4D;
@@ -98,6 +100,7 @@ public class x86_64_v2 extends Machine {
     static RegMask callInMask( TypeFunPtr tfp, int idx, int maxArgSlot ) {
         if( idx==0 ) return RPC_MASK;
         if( idx==1 ) return null;
+        if( idx-2 >= tfp.nargs() ) return null; // Anti-dependence
         return switch( CodeGen.CODE._callingConv ) {
         case "SystemV" -> callSys5 (tfp,idx,maxArgSlot);
         case "Win64"   -> callWin64(tfp,idx,maxArgSlot);
@@ -252,9 +255,9 @@ public class x86_64_v2 extends Machine {
         case AndNode      and -> and(and);
         case BoolNode    bool -> cmp(bool);
         case CProjNode      c -> new CProjNode(c);
-        case CallEndNode cend -> new CallEndX86(cend);
+        case CallEndNode cend -> new CallEndMach(cend);
         case CallNode    call -> call(call);
-        case CastNode    cast -> new CastX86(cast);
+        case CastNode    cast -> new CastMach(cast);
         case ConstantNode con -> con(con);
         case DivFNode    divf -> new DivFX86(divf);
         case DivNode      div -> new DivX86(div);
@@ -273,7 +276,7 @@ public class x86_64_v2 extends Machine {
         case MemPhiNode phi -> new MemPhiNode(phi);
         case PhiNode      phi -> new PhiNode(phi);
         case ProjNode     prj -> prj(prj);
-        case ReadOnlyNode read-> new ReadOnlyNode(read);
+        case ReadOnlyNode read-> new ReadOnlyMach(read);
         case ReturnNode   ret -> new RetX86(ret, ret.fun());
         case SarNode      sar -> sar(sar);
         case ShlNode      shl -> shl(shl);
@@ -410,15 +413,16 @@ public class x86_64_v2 extends Machine {
     }
 
     private Node con( ConstantNode con ) {
-        if(!con._con.isConstant()) return new ConstantNode(con); // Default unknown caller inputs
+        if( !con._con.isConstant() )
+            return new ConstantNode(con); // Default unknown caller inputs
         return switch (con._con) {
-            case TypeInteger ti -> new IntX86(con);
-            case TypeFloat tf -> new FltX86(con);
-            case TypeFunPtr tfp -> new TFPX86(con);
-            case TypeMemPtr tmp -> throw Utils.TODO();
-            case TypeNil tn -> throw Utils.TODO();
-            // TOP, BOTTOM, XCtrl, Ctrl, etc.  Never any executable code.
-            case Type t -> t == Type.NIL ? new IntX86(con) : new ConstantNode(con);
+        case TypeInteger ti -> new IntX86(con);
+        case TypeFloat   tf -> new FltX86(con);
+        case TypeFunPtr tfp -> new TFPX86(con);
+        case TypeMemPtr tmp -> new TMPX86(con);
+        case TypeNil tn -> throw Utils.TODO();
+        // TOP, BOTTOM, XCtrl, Ctrl, etc.  Never any executable code.
+        case Type t -> t == Type.NIL ? new IntX86(con) : new ConstantNode(con);
         };
     }
 
@@ -455,6 +459,8 @@ public class x86_64_v2 extends Machine {
     }
 
     private Node prj( ProjNode prj ) {
+        TypeInteger ret = cReturn(prj);
+        if( ret!=null ) return new ExtendX86(prj,ret);
         return new ProjX86(prj);
     }
 
diff --git a/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java b/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java
index 09ebd51b..1cc83813 100644
--- a/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java
+++ b/src/main/java/com/seaofnodes/simple/print/ASMPrinter.java
@@ -68,7 +68,7 @@ public final class ASMPrinter extends AssemblyAdapter<Node> {
         var data=new ArrayList<Data>();
         for( Encoding.Relo r : relos ) {
             int align=1<<r._align;
-            int size=align;
+            int size=r._t instanceof TypeStruct ? (r._structSize+align-1)&-align : align;
             if( r._t instanceof TypeTuple t ) size=align*t._types.length;
             data.add(new Data(r._t,r._t.str(),r._align,size));
         }
diff --git a/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java b/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
index b9aabba3..3d10a80c 100644
--- a/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
+++ b/src/main/java/com/seaofnodes/simple/print/SimpleGraphAdapter.java
@@ -6,7 +6,7 @@ import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.node.Node;
 import com.seaofnodes.simple.type.TypeMem;
 
-/** Chapter 21's view of the IR; browser, transport and layout are shared. */
+/** Chapter 22's view of the IR; browser, transport and layout are shared. */
 public class SimpleGraphAdapter extends GraphAdapter<Node> {
 
     @Override protected String edgeName(Node n, int i) {
diff --git a/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java b/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
index d8d0e216..22b6beba 100644
--- a/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
+++ b/src/main/java/com/seaofnodes/simple/print/SimpleGraphObserver.java
@@ -7,7 +7,7 @@ import com.seaofnodes.simple.node.Node;
 import java.util.ArrayList;
 import java.io.IOException;
 
-/** Chapter 21's compilation context; capture and event bookkeeping are shared. */
+/** Chapter 22's compilation context; capture and event bookkeeping are shared. */
 public class SimpleGraphObserver extends GraphCapture<Node> {
     private CodeGen _code;
     public SimpleGraphObserver() { super(new SimpleGraphAdapter()); }
diff --git a/src/main/java/com/seaofnodes/simple/sys.java b/src/main/java/com/seaofnodes/simple/sys.java
new file mode 100644
index 00000000..45106770
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/sys.java
@@ -0,0 +1,25 @@
+package com.seaofnodes.simple;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+
+/** Default included namespaces for Simple.
+
+    You can think of this as {@code #include <stdio.h>} for C or {@code import java.lang.*} for Java.
+ */
+public abstract class sys {
+
+    public static final String SYS;
+
+    static {
+        try {
+            SYS = Files.readString(Path.of("src/main/smp/sys.smp"));
+        }
+        catch( Exception e ) {
+            throw new RuntimeException(e);
+        }
+    }
+
+}
diff --git a/src/main/java/com/seaofnodes/simple/sys/sys.smp b/src/main/java/com/seaofnodes/simple/sys/sys.smp
new file mode 100644
index 00000000..4ac925db
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/sys/sys.smp
@@ -0,0 +1,58 @@
+// -*- mode: java;  -*-
+
+// top-level default import
+struct sys {
+    // libc bindings
+    /** https://www.man7.org/linux/man-pages/man2/<libc call>.2.html */
+    struct libc {
+        i32 errno = "C";
+        // fd  buf len -> len
+        {  i32 i64 u32 -> u32 } write = "C";
+        // fd  buf len -> len
+        {  i32 i64 u32 -> u32 } read = "C";
+        // status
+        {  i32 -> i32 } _exit = "C";
+        // addr len prot flags fd  off -> void*
+        {  i64  i64 i32  i32   i32 i32 -> i64 } mmap = "C";
+        // mmap flags
+        i32 PROT_EXEC = 4;
+        i32 PROT_READ = 1;
+        i32 PROT_WRITE= 2;
+        i32 PROT_NONE = 0;
+        i32 MAP_PRIVATE = 2;
+        i32 MAP_ANON = 32;
+    };
+    struct ary {
+        val copy = { u8[] dst, int doff, u8[~] src, int soff, int len ->
+            for( int i=0; i<len; i++ )
+                dst[i+doff] = src[i+soff];
+            return dst;
+        };
+    };
+    struct io {
+        // Print string to stdout
+        val p = { u8[~] str ->
+            i64 ptr = str;  // cast array base to i64
+            return sys.libc.write(1,ptr,str#);
+        };
+
+        // Return stdin as a u8[]
+        val stdin = { ->
+            var buf = new u8[8*1024];
+            i64 ptr = buf;
+            int len = 0;
+            while( true ) {
+                int rez = sys.libc.read(0,ptr,buf#);
+                if( rez < 0 ) sys.libc._exit(sys.libc.errno);
+                len += rez;
+                if( rez < buf# )
+                    break;
+                sys.libc._exit(-2); // Need to implement
+            }
+            // Compress
+            var dst = new u8[len];
+            return sys.ary.copy(dst,0,buf,0,len);
+        };
+
+    };
+};
diff --git a/src/main/java/com/seaofnodes/simple/type/Field.java b/src/main/java/com/seaofnodes/simple/type/Field.java
index c93f82e7..94afcd26 100644
--- a/src/main/java/com/seaofnodes/simple/type/Field.java
+++ b/src/main/java/com/seaofnodes/simple/type/Field.java
@@ -51,8 +51,10 @@ public class Field extends Type {
     @Override
     public Field dual() { return make(_fname,_type.dual(),_alias,!_final); }
 
-    @Override public Field glb() {
-        Type glb = _type.glb();
+    @Override public boolean isConstant() { return _type.isConstant(); }
+
+    @Override public Field glb(boolean mem) {
+        Type glb = _type.glb(mem);
         return (glb==_type && _final) ? this : make(_fname,glb,_alias,true);
     }
 
@@ -70,5 +72,5 @@ public class Field extends Type {
         return _type.print(sb.p(_final?"":"!").p(_fname).p(":").p(_alias).p(" : "));
     }
 
-    @Override public String str() { return _fname; }
+    @Override public String str() { return (_final?"":"!")+_fname; }
 }
diff --git a/src/main/java/com/seaofnodes/simple/type/Type.java b/src/main/java/com/seaofnodes/simple/type/Type.java
index 96b2c6ef..4fad33cb 100644
--- a/src/main/java/com/seaofnodes/simple/type/Type.java
+++ b/src/main/java/com/seaofnodes/simple/type/Type.java
@@ -44,7 +44,8 @@ public class Type {
     static final byte TMEM    =13; // All memory (alias 0) or A slice of memory - with specific alias
     static final byte TSTRUCT =14; // Structs; tuples with named fields
     static final byte TFLD    =15; // Named fields in structs
-    static final byte TRPC    =16; // Return Program Control (Return PC or RPC)
+    static final byte TCONARY =16; // Constant array
+    static final byte TRPC    =17; // Return Program Control (Return PC or RPC)
 
     public final byte _type;
 
@@ -75,6 +76,7 @@ public class Type {
         TypeStruct.gather(ts);
         TypeTuple.gather(ts);
         TypeRPC.gather(ts);
+        TypeConAry.gather(ts);
         int sz = ts.size();
         for( int i = 0; i < sz; i++ )
             ts.add(ts.get(i).dual());
@@ -160,6 +162,7 @@ public class Type {
         // RHS TypeNil vs NIL/XNIL
         if( _type==  TNIL ) return t instanceof TypeNil ptr ? ptr.meet0() : (t._type==TXNIL ? TypePtr.PTR : BOTTOM);
         if( _type== TXNIL ) return t instanceof TypeNil ptr ? ptr.meetX() : (t._type== TNIL ? TypePtr.PTR : BOTTOM);
+
         // 'this' is only {TCTRL,TXCTRL}
         // Other non-simple RHS things bottom out
         if( !t.is_simple() ) return BOTTOM;
@@ -200,8 +203,9 @@ public class Type {
     // Make a zero version of this type, 0 for integers and null for pointers.
     public Type makeZero() { return Type.NIL; }
 
-    /** Compute greatest lower bound in the lattice */
-    public Type glb() { return Type.BOTTOM; }
+    /** Compute greatest lower bound in the lattice.  If values are in memory,
+     *  ints and floats cannot widen. */
+    public Type glb(boolean mem) { return Type.BOTTOM; }
 
     // Writable array slots are invariant in their element access permissions.
     // Otherwise an alias could insert a readonly pointer into a writable slot.
@@ -222,7 +226,9 @@ public class Type {
     // Sizes are expected to be between 1 and 64 bits.
     // Size 0 means this either takes no space (such as a known-zero field)
     // or isn't a scalar to be stored in memory.
-    public int log_size() { return 3; }
+    public int log_size () { return 3; } // log-size of a type; log_size for a struct is usually undefined
+    public int size() { return 1<<log_size(); }
+    public int alignment() { return log_size(); } // alignment; for structs, max align of Fields
 
     // ----------------------------------------------------------
     // Useful in the debugger, which calls toString everywhere.
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeConAry.java b/src/main/java/com/seaofnodes/simple/type/TypeConAry.java
new file mode 100644
index 00000000..692450d0
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/type/TypeConAry.java
@@ -0,0 +1,69 @@
+package com.seaofnodes.simple.type;
+
+import com.seaofnodes.simple.Utils;
+import java.util.ArrayList;
+import java.io.ByteArrayOutputStream;
+
+/**
+ * Represents a constant array of primitives
+ */
+public class TypeConAry<A> extends Type {
+    boolean _any;
+    // One of byte,short,int,long,float,double array
+    public final A _ary;
+
+    TypeConAry( boolean any, A ary ) { super(TCONARY); _any = any; _ary = ary; }
+    private static final TypeConAry TOP = new TypeConAry(true ,null).intern();
+    public  static final TypeConAry BOT = new TypeConAry(false,null).intern();
+    public static void gather(ArrayList<Type> ts) {
+        ts.add(BOT);
+        ts.add(TypeConAryB.ABC);
+        ts.add(TypeConAryB.ABCD);
+        ts.add(TypeConAryI.I123);
+    }
+
+    @Override public String str() { return (_any?"~":"") + "[]"; }
+    @Override public boolean isConstant() { return true; }
+    @Override public TypeConAry dual() {
+        if( this== BOT ) return TOP;
+        if( this== TOP ) return BOT;
+        return this;
+    }
+
+    @Override Type xmeet(Type t) {
+        TypeConAry ary = (TypeConAry)t; // Invariant
+        if( this==TOP ) return ary ;
+        if( ary ==TOP ) return this;
+        assert _ary!=ary._ary;  // Already interned and this!=t
+        return BOT;
+    }
+
+    // Meet-over-elements type
+    public Type elem() {
+        if( _ary==null )
+            return _any ? TOP : BOTTOM;
+        int len = len();
+        long min = Long.MAX_VALUE;
+        long max = Long.MIN_VALUE;
+        for( int i=0; i<len; i++ ) {
+            min = Math.min(min,at(i));
+            max = Math.max(max,at(i));
+        }
+        return TypeInteger.make(min,max);
+    }
+    public long at(int idx) { throw Utils.TODO(); }
+    public int len() { throw Utils.TODO(); }
+    @Override public int alignment() { return 0; }
+    public void write( ByteArrayOutputStream baos ) { throw Utils.TODO(); }
+
+    @Override boolean eq(Type t) {
+        TypeConAry ary = (TypeConAry)t; // Invariant
+        return _any==ary._any && ary._ary==null;
+    }
+
+    @Override int hash() {
+        assert _ary==null;
+        return _any ? 1024 : 0;
+    }
+
+}
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeConAryB.java b/src/main/java/com/seaofnodes/simple/type/TypeConAryB.java
new file mode 100644
index 00000000..b56beb47
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/type/TypeConAryB.java
@@ -0,0 +1,18 @@
+package com.seaofnodes.simple.type;
+
+import java.util.Arrays;
+import java.io.ByteArrayOutputStream;
+
+public class TypeConAryB extends TypeConAry<byte[]> {
+    private TypeConAryB(byte[] bs) { super(false,bs); }
+    public static TypeConAryB make( byte[] bs ) { return new TypeConAryB(bs).intern(); }
+    public static TypeConAryB make( String s ) { return make(s.getBytes()); }
+    static final TypeConAryB ABC  = make("abc");
+    static final TypeConAryB ABCD = make("abcd");
+    @Override public long at(int idx) { return _ary[idx]; }
+    @Override public int len() { return _ary.length; }
+    @Override public String str() { return "[\""+new String(_ary)+"\"]"; }
+    @Override boolean eq(Type t) { return Arrays.equals(_ary,((TypeConAryB)t)._ary); }
+    @Override int hash() { return Arrays.hashCode(_ary); }
+    @Override public void write( ByteArrayOutputStream baos ) { baos.write(_ary,0,_ary.length); }
+}
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeConAryI.java b/src/main/java/com/seaofnodes/simple/type/TypeConAryI.java
new file mode 100644
index 00000000..4859e839
--- /dev/null
+++ b/src/main/java/com/seaofnodes/simple/type/TypeConAryI.java
@@ -0,0 +1,13 @@
+package com.seaofnodes.simple.type;
+
+import java.util.Arrays;
+
+public class TypeConAryI extends TypeConAry<int[]> {
+    private TypeConAryI(int[] bs) { super(false,bs); }
+    public static TypeConAryI make( int[] bs ) { return new TypeConAryI(bs).intern(); }
+    static final TypeConAryI I123  = make(new int[]{1,2,3});
+    @Override public String str() { return "[i32]"; }
+    @Override public int alignment() { return 2; }
+    @Override boolean eq(Type t) { return Arrays.equals(_ary,((TypeConAryI)t)._ary); }
+    @Override int hash() { return Arrays.hashCode(_ary); }
+}
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeFloat.java b/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
index aa205149..a0940f8b 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeFloat.java
@@ -81,7 +81,7 @@ public class TypeFloat extends Type {
     }
 
     @Override public Type makeZero() { return FZERO; }
-    @Override public Type glb() { return F64; }
+    @Override public Type glb(boolean mem) { return mem ? (isHigh() ? dual() : this)  : F64; }
 
     @Override
     int hash() { return (int)(Double.hashCode(_con) ^ _sz ^ (1<<17)); }
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java b/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java
index 1bd73732..e6701360 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeFunPtr.java
@@ -59,7 +59,7 @@ public class TypeFunPtr extends TypeNil {
     // RHS is NIL; do not deep-dual when crossing the centerline
     @Override public Type meet0() { return _nil==3 ? this : make((byte)3,_sig,_ret,_fidxs); }
 
-    @Override public TypeFunPtr glb() { return make((byte)3,_sig,_ret,-1L); }
+    @Override public TypeFunPtr glb(boolean mem) { return make((byte)3,_sig,_ret,-1L); }
 
     @Override public boolean isHigh    () { return _nil <= 1 || (_nil==2 && _fidxs==0); }
     @Override public boolean isConstant() { return (_nil==2 && Long.bitCount(_fidxs)==1) || (_nil==3 && _fidxs==0); }
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeInteger.java b/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
index cccb85a5..59378ef3 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeInteger.java
@@ -75,11 +75,17 @@ public class TypeInteger extends Type {
     @Override public boolean isConstant() { return _min == _max; }
 
     @Override public int log_size() {
+        if( isHigh() ) return 0; // High types are dead, and should never hit code emission.
         if( this==I8  || this==U8 || this==BOOL ) return 0; // 1<<0 == 1 bytes
         if( this==I16 || this==U16              ) return 1; // 1<<1 == 2 bytes
         if( this==I32 || this==U32              ) return 2; // 1<<2 == 4 bytes
         if( this==BOT                           ) return 3; // 1<<3 == 8 bytes
-        if( isHighOrConst() ) return 0;
+        if( isConstant() ) {                                // just const here
+            if (-0xFF <= _min && _min <= 0xFF)                    return 0;
+            else if (-0xFFFF <= _min && _min <= 0xFFFF)           return 1;
+            else if (-0xFFFFFFFFL <= _min && _min <= 0xFFFFFFFFL) return 2;
+            else return 3;
+        }
         throw Utils.TODO();
     }
 
@@ -119,7 +125,7 @@ public class TypeInteger extends Type {
         return this;
     }
     @Override public Type makeZero() { return ZERO; }
-    @Override public TypeInteger glb() { return BOT; }
+    @Override public Type glb(boolean mem) { return mem ? (isHigh() ? dual() : this) : BOT; }
     @Override int hash() { return Utils.fold(_min) * Utils.fold(_max); }
     @Override public boolean eq( Type t ) {
         TypeInteger i = (TypeInteger)t; // Contract
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeMem.java b/src/main/java/com/seaofnodes/simple/type/TypeMem.java
index fe393a88..74bcbd8f 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeMem.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeMem.java
@@ -50,7 +50,8 @@ public class TypeMem extends Type {
     }
 
     @Override public boolean isHigh() { return _t.isHigh(); }
-    @Override public Type glb() { return make(_alias,_t.glb()); }
+    @Override public int log_size() { throw Utils.TODO(); }
+    @Override public Type glb(boolean mem) { return make(_alias,_t.glb(true)); }
 
     @Override int hash() { return 9876543 + _alias + _t.hashCode(); }
 
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java b/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
index 98e92bca..34033119 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeMemPtr.java
@@ -28,25 +28,29 @@ public class TypeMemPtr extends TypeNil {
     // Deep read-only access through this pointer; independent of slot finality.
     public boolean _ro;
 
+    public final boolean _one;  // Singleton instance
 
-    private TypeMemPtr(byte nil, TypeStruct obj) {
+    private TypeMemPtr(byte nil, TypeStruct obj, boolean singleton) {
         super(TMEMPTR,nil);
         assert obj!=null;
         _obj = obj;
         _ro = obj==TypeStruct.BOT;
+        _one = singleton;
     }
-    static TypeMemPtr make(byte nil, TypeStruct obj) { return new TypeMemPtr(nil, obj).intern(); }
+    public static TypeMemPtr make(byte nil, TypeStruct obj, boolean one) { return new TypeMemPtr(nil, obj, one).intern(); }
+    static TypeMemPtr make(byte nil, TypeStruct obj) { return make(nil, obj, false); }
+    public static TypeMemPtr make        (TypeStruct obj) { return make((byte)2, obj); }
     public static TypeMemPtr makeNullable(TypeStruct obj) { return make((byte)3, obj); }
-    public static TypeMemPtr make(TypeStruct obj) { return new TypeMemPtr((byte)2, obj).intern(); }
-    public TypeMemPtr makeFrom(TypeStruct obj) { return obj==_obj ? this : make(_nil, obj).withAccess(_ro); }
+
+    public TypeMemPtr makeFrom(TypeStruct obj) { return obj==_obj ? this : make(_nil, obj, _one).withAccess(_ro); }
     public TypeMemPtr makeNullable() { return makeFrom((byte)3); }
-    @Override TypeMemPtr makeFrom(byte nil) { return nil==_nil ? this : make(nil,_obj).withAccess(_ro); }
+    @Override TypeMemPtr makeFrom(byte nil) { return nil==_nil ? this : make(nil, _obj, _one).withAccess(_ro); }
     @Override public TypeMemPtr makeRO() { return withAccess(true); }
     @Override public boolean isFinal() { return _ro; }
 
     public TypeMemPtr withAccess(boolean ro) {
         if( _ro==ro ) return this;
-        TypeMemPtr ptr = new TypeMemPtr(_nil, _obj);
+        TypeMemPtr ptr = new TypeMemPtr(_nil, _obj, _one);
         ptr._ro = ro;
         return ptr.intern();
     }
@@ -73,15 +77,16 @@ public class TypeMemPtr extends TypeNil {
     @Override
     public TypeNil xmeet(Type t) {
         TypeMemPtr that = (TypeMemPtr) t;
-        return TypeMemPtr.make(xmeet0(that), (TypeStruct)_obj.meet(that._obj)).withAccess(_ro | that._ro);
+        return make(xmeet0(that), (TypeStruct)_obj.meet(that._obj), _one & that._one).withAccess(_ro | that._ro);
     }
 
     @Override
-    public TypeMemPtr dual() { return TypeMemPtr.make( dual0(), _obj.dual()).withAccess(!_ro); }
+    public TypeMemPtr dual() { return make( dual0(), _obj.dual(), !_one).withAccess(!_ro); }
 
     // RHS is NIL; do not deep-dual when crossing the centerline
     @Override Type meet0() { return _nil==3 ? this : make((byte)3,_obj).withAccess(_ro); }
 
+    @Override public boolean isConstant() { return _one && _obj.isConstant(); }
 
     // True if this "isa" t up to named structures
     @Override public boolean shallowISA( Type t ) {
@@ -94,17 +99,17 @@ public class TypeMemPtr extends TypeNil {
         throw Utils.TODO(); // return _obj.shallowISA(that._obj);
     }
 
-    @Override public TypeMemPtr glb() { return make((byte)3,_obj.glb()).withAccess(true); }
+    @Override public TypeMemPtr glb(boolean mem) { return make((byte)3,_obj.glb(true)).withAccess(true); }
     // Is forward-reference
     @Override public boolean isFRef() { return _obj.isFRef(); }
 
     @Override public int log_size() { return 3; } // (1<<3)==8-byte pointers
 
-    @Override int hash() { return (_ro ? 8192 : 0) ^ _obj.hashCode() ^ super.hash(); }
+    @Override int hash() { return (_ro ? 8192 : 0) ^ _obj.hashCode() ^ super.hash() ^ (_one ? 2048 : 0); }
 
     @Override boolean eq(Type t) {
         TypeMemPtr ptr = (TypeMemPtr)t; // Invariant
-        return _ro==ptr._ro && _obj == ptr._obj  && super.eq(ptr);
+        return _ro==ptr._ro && _obj == ptr._obj && _one == ptr._one && super.eq(ptr);
     }
 
     @Override public String str() {
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeNil.java b/src/main/java/com/seaofnodes/simple/type/TypeNil.java
index aee623ba..3902c40b 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeNil.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeNil.java
@@ -48,7 +48,7 @@ public abstract class TypeNil extends Type {
     @Override public boolean isConstant   () { return false; }
     @Override public boolean isHighOrConst() { return isHigh() || isConstant(); }
 
-    @Override public Type glb() { return Type.NIL; }
+    @Override public Type glb(boolean mem) { return Type.NIL; }
 
     public boolean notNull() { return _nil==1 || _nil==2; }
     public boolean nullable() { return _nil==3; }
diff --git a/src/main/java/com/seaofnodes/simple/type/TypePtr.java b/src/main/java/com/seaofnodes/simple/type/TypePtr.java
index e9091c25..d9de5cd7 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypePtr.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypePtr.java
@@ -45,7 +45,7 @@ public class TypePtr extends TypeNil {
     // 0->xscalar, 1->nscalar, 2->nscalar, 3->scalar
     @Override Type meetX() { return _nil==0 ? XNIL : (_nil==3 ? PTR : NPTR); }
 
-    @Override public TypePtr glb() { return PTR; }
+    @Override public TypePtr glb(boolean mem) { return PTR; }
 
     private static final String[] STRS = new String[]{"~ptr","~nptr","nptr","ptr"};
     @Override public String str() { return STRS[_nil]; }
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeStruct.java b/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
index 990c5fcf..cde0bc93 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeStruct.java
@@ -24,15 +24,18 @@ public class TypeStruct extends Type {
     // "bottom out" is again the forward-ref struct.
     public final String _name;
     public final Field[] _fields;
+    public final TypeConAry _con; // Optional, constant array contents
 
-    TypeStruct(String name, Field[] fields) {
+    private TypeStruct(String name, TypeConAry con, Field[] fields) {
         super(TSTRUCT);
         _name = name;
         _fields = fields;
+        _con = con;
     }
 
     // All fields directly listed
-    public static TypeStruct make(String name, Field... fields) { return new TypeStruct(name, fields).intern(); }
+    public static TypeStruct make(String name, TypeConAry con, Field... fields) { return new TypeStruct(name, con, fields).intern(); }
+    public static TypeStruct make(String name, Field... fields) { return make(name, TypeConAry.BOT, fields); }
     public static final TypeStruct TOP = make("$TOP",new Field[0]);
     public static final TypeStruct BOT = make("$BOT",new Field[0]);
     public static final TypeStruct TEST = make("test",new Field[]{Field.TEST});
@@ -48,12 +51,16 @@ public class TypeStruct extends Type {
     }
 
     // Array
-    public static TypeStruct makeAry(TypeInteger len, int lenAlias, Type body, int bodyAlias) {
+    public static TypeStruct makeAry(String name, TypeInteger len, int lenAlias, Type body, int bodyAlias) {
+        return makeAry(name,len,lenAlias,body,bodyAlias,false,TypeConAry.BOT);
+    }
+    public static TypeStruct makeAry(String name, TypeInteger len, int lenAlias, Type body, int bodyAlias, boolean efinal, TypeConAry con) {
         assert body instanceof TypeInteger || body instanceof TypeFloat || (body instanceof TypeNil tn && tn.nullable());
-        assert len.isa(TypeInteger.U32);
-        return make("[" + body.str() + "]",
+        assert efinal || con==TypeConAry.BOT; // No mutable constant arrays
+        return make(name,
+                    con,
                     Field.make("#" ,len , lenAlias,true ),
-                    Field.make("[]",body,bodyAlias,false));
+                    Field.make("[]",body,bodyAlias,efinal));
     }
 
     // A pair of self-cyclic types
@@ -62,9 +69,11 @@ public class TypeStruct extends Type {
     public  static final TypeStruct S1  = make("S1", Field.make("a", TypeInteger.BOT, -1, false), Field.make("s2",TypeMemPtr.make((byte)2,S2F),-2, false) );
     private static final TypeStruct S2  = make("S2", Field.make("b", TypeFloat  .F64, -3, false), Field.make("s1",TypeMemPtr.make((byte)2,S1F),-4, false) );
 
-    private static final TypeStruct ARY = makeAry(TypeInteger.U32,-1,TypeInteger.BOT,-2);
+    private static final TypeStruct ARY = makeAry("[i64]",TypeInteger.U32,-1,TypeInteger.BOT,-2);
+    private static final TypeStruct STR = makeAry("[u8]",TypeInteger.U32,-1,TypeInteger.U8,-2);
+    private static final TypeStruct HELLO= makeAry("[u8]",TypeInteger.constant(3),-1,TypeInteger.U8,-2,true,TypeConAryB.ABC);
 
-    public static void gather(ArrayList<Type> ts) { ts.add(TEST); ts.add(BOT); ts.add(S1); ts.add(S2); ts.add(ARY); }
+    public static void gather(ArrayList<Type> ts) { ts.add(TEST); ts.add(BOT); ts.add(S1); ts.add(S2); ts.add(ARY); ts.add(STR); ts.add(HELLO); }
 
     // Find field index by name
     public int find(String fname) {
@@ -114,7 +123,8 @@ public class TypeStruct extends Type {
                 return BOT;
             flds[i] = (Field)f0.meet(f1);
         }
-        return make(_name,flds);
+        TypeConAry con = (TypeConAry)_con.meet(that._con);
+        return make(_name, con, flds);
     }
 
     @Override
@@ -125,22 +135,23 @@ public class TypeStruct extends Type {
         Field[] flds = new Field[_fields.length];
         for( int i=0; i<_fields.length; i++ )
             flds[i] = _fields[i].dual();
-        return make(_name,flds);
+        TypeConAry con = _con.dual();
+        return make(_name,con,flds);
     }
 
     // Keeps the same struct, but lower-bounds all fields.
-    @Override public TypeStruct glb() {
-        if( _glb() ) return this;
+    @Override public TypeStruct glb(boolean mem) {
+        if( _glb(mem) ) return this;
         // Need to glb each field
         Field[] flds = new Field[_fields.length];
         for( int i=0; i<_fields.length; i++ )
-            flds[i] = _fields[i].glb();
+            flds[i] = _fields[i].glb(mem);
         return make(_name,flds);
     }
-    private boolean _glb() {
+    private boolean _glb(boolean mem) {
         if( _fields!=null )
           for( Field f : _fields )
-              if( f.glb() != f )
+              if( f.glb(mem) != f )
                  return false;
         return true;
     }
@@ -156,10 +167,56 @@ public class TypeStruct extends Type {
         return true;
     }
 
+    @Override public boolean isConstant() {
+        int len = _fields.length;
+        // If we have a constant array, then ignore the last 2 array fields-
+        // they are effectively constant.
+
+        // Fields are given sizes according to their types at *offset time*.
+        // And thus layout, packing & padding are determined by the Types
+        // at *offset-time*, which means *offset-time* has to be picked
+        // when types are Stable - post/during TypeCheck.
+
+        // The array-length field is shared with other like-sized arrays, so
+        // you are allowed to mix "abc" and "very_hugh_>256_char_string" and
+        // the resulting TMP can query the length field (getting 3 or >256
+        // respectively), and reading from a prolly 16bit length field.
+
+        // Basically asking: forward-flow declared-types, are these compatible?
+        // Only array-lengths have an issue here?  So internally name fields
+        // `#0` or `#1` or `#2` or `#3`.
+        //
+        // Also means I cannot track exact array length without losing the
+        // "declared type requires a 4-byte field".
+        //
+        // Same-same for all fields in a struct, space in memory is based on
+        // declared-type at least, possible (future work) optimized where all
+        // memory versions of the same field get a smaller footprint (or even a
+        // constant past or moved into prototype) past construction
+
+        if( _con!=TypeConAry.BOT ) len -= 2;
+        // Check all fields for being constant
+        for( int i=0; i<len; i++ )
+            if( !_fields[i].isConstant() )
+                return false;
+        return true;
+    }
+
+    // log_size for a struct is not defined, unless its exactly some power of
+    // 2.  *Total size* is well-defined, and is available in the offsets.
+    @Override public int log_size() { throw Utils.TODO(); }
+    @Override public int size() { return offset(_fields.length); }
+    @Override public int alignment() {
+        int align = 0;
+        for( Field f : _fields )
+            align = Math.max(align, (f._fname!="[]" || _con==TypeConAry.BOT ? f._type : _con).alignment());
+        return align;
+    }
+
     @Override
     boolean eq(Type t) {
         TypeStruct ts = (TypeStruct)t; // Invariant
-        if( !_name.equals(ts._name) )
+        if( !_name.equals(ts._name) || _con!=ts._con )
             return false;
         if( _fields == ts._fields ) return true;
         if( _fields==null || ts._fields==null ) return false;
@@ -177,19 +234,17 @@ public class TypeStruct extends Type {
         if( _fields != null )
             for( Field f : _fields )
                 hash = Utils.rot(hash,13) ^ f.hashCode();
-        return Utils.fold(hash);
+        return Utils.fold(hash ^ _con.hashCode());
     }
 
     @Override
     public SB print(SB sb) {
         if( this==BOT ) return sb.p("StructBot");
         if( this==TOP ) return sb.p("StructTop");
-        if( _fields == null ) return sb.p(_name); // Forward reference struct, just print the name
-        if( isAry() ) {
-            if( !isFinal() ) sb.p("!");
-            return sb.p(_name); // Skip printing generic array fields
-        }
+        if( _con!=TypeConAry.BOT ) return sb.p(_con.str());
         sb.p(_name);
+        if( _fields == null || isAry() ) // Forward reference struct, just print the name
+            return sb.p(isFinal() ? "" : "!");
         sb.p(" {");
         for( Field f : _fields )
             f._type.print(sb).p(f._final ? " " : " !").p(f._fname).p("; ");
@@ -204,11 +259,11 @@ public class TypeStruct extends Type {
     @Override public String str() {
         if( this==BOT ) return "StructBot";
         if( this==TOP ) return "StructTop";
-        return _name;
+        return _con==TypeConAry.BOT ? _name : _con.str();
     }
 
 
-    public boolean isAry() { return _fields.length==2 && _fields[1]._fname.equals("[]"); }
+    public boolean isAry() { return _fields.length>=2 && _fields[_fields.length-1]._fname=="[]"; }
 
     public int aryBase() {
         assert isAry();
@@ -231,14 +286,12 @@ public class TypeStruct extends Type {
         // Compute a layout for a collection of fields
         assert _fields != null; // No forward refs
 
-        // Array layout is different: len,[pad],body...
-        if( isAry() )
-            return _offs = new int[]{ 0, _fields[1]._type.log_size() < 3 ? 4 : 8 };
-
         // Compute a layout
-        int[] cnts = new int[4]; // Count of fields at log field size
-        for( Field f : _fields )
-            cnts[f._type.log_size()]++; // Log size is 0(byte), 1(i16/u16), 2(i32/f32), 3(i64/dbl)
+        int[] cnts = new int[5]; // Count of fields at log field size
+        int flen = _fields.length;
+        if( isAry() ) flen--;   // Array field is aligned differently
+        for( int i=0; i<flen; i++ )
+            cnts[_fields[i]._type.log_size()]++; // Log size is 0(byte), 1(i16/u16), 2(i32/f32), 3(i64/dbl)
         int off = 0, idx = 0; // Base common struct fields go here, e.g. Mark/Klass
         // Compute offsets to the start of each power-of-2 aligned fields.
         int[] offs = new int[4];
@@ -249,14 +302,38 @@ public class TypeStruct extends Type {
         // Assign offsets to all fields.
         // Really a hidden radix sort.
         _offs = new int[_fields.length+1];
-        for( Field f : _fields ) {
-            int log = f._type.log_size();
+        for( int i=0; i<flen; i++ ) {
+            int log = _fields[i]._type.log_size();
             _offs[idx++] = offs[log]; // Field offset
             offs[log] += 1<<log;      // Next field offset at same alignment
             cnts[log]--;              // Count down, should be all zero at end
         }
-        _offs[_fields.length] = (off+7)& ~7; // Round out to max alignment
+
+        // Array bits
+        if( isAry() ) {
+            // Pad out to the element alignment
+            int align = (_fields[flen]._fname!="[]" || _con==TypeConAry.BOT ? _fields[flen]._type : _con).alignment();
+            off = (off + ((1<<align)-1)) & -(1<<align);
+            _offs[flen] = off;
+            if( _con!=TypeConAry.BOT )
+                _offs[flen+1] = off+_con.len();
+        } else
+            _offs[flen] = off; // Max struct size, no trailing padding
         return _offs;
     }
 
+    // Field order with increasing offset
+    public int[] layout() {
+        offset(0);
+        int len = _offs.length;
+        int[] is = new int[len];
+        for( int i=0; i<len; i++ ) is[i] = i;
+        // Stoopid hand rolled bubble sort
+        for( int i=0; i<len; i++ )
+            for( int j=i+1; j<len; j++ )
+                if( _offs[is[j]] < _offs[is[i]] )
+                    { int tmp = is[i]; is[i] = is[j]; is[j] = tmp; }
+        return is;
+    }
+
 }
diff --git a/src/main/java/com/seaofnodes/simple/type/TypeTuple.java b/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
index d3b19b52..bc57871a 100644
--- a/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
+++ b/src/main/java/com/seaofnodes/simple/type/TypeTuple.java
@@ -1,6 +1,7 @@
 package com.seaofnodes.simple.type;
 
 import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.Utils;
 import java.util.ArrayList;
 
 public class TypeTuple extends Type {
@@ -48,11 +49,10 @@ public class TypeTuple extends Type {
         return make(ts);
     }
 
-    @Override
-    public Type glb() {
+    @Override public Type glb(boolean mem) {
         Type[] ts = new Type[_types.length];
         for( int i=0; i<_types.length; i++ )
-            ts[i] = _types[i].glb();
+            ts[i] = _types[i].glb(mem);
         return make(ts);
     }
 
@@ -63,12 +63,13 @@ public class TypeTuple extends Type {
         return true;
     }
 
-    @Override public int log_size() {
+    @Override public int log_size() { throw Utils.TODO(); }
+    @Override public int alignment() {
         assert isConstant();
-        int log_size = 0;
+        int align = 0;
         for( Type t : _types )
-            log_size = Math.max(log_size,t.log_size());
-        return log_size;
+            align = Math.max(align,t.alignment());
+        return align;
     }
 
     public Type ret() { assert _types.length==3; return _types[2]; }
diff --git a/src/main/smp/sys.smp b/src/main/smp/sys.smp
new file mode 100644
index 00000000..ede08d63
--- /dev/null
+++ b/src/main/smp/sys.smp
@@ -0,0 +1,57 @@
+// -*- mode: java;  -*-
+
+// top-level default import
+struct sys {
+    // libc bindings
+    /** https://www.man7.org/linux/man-pages/man2/<libc call>.2.html */
+    struct libc {
+        i32 errno = "C";
+        // fd  buf len -> len
+        {  i32 i64 u32 -> u32 } write = "C";
+        // fd  buf len -> len
+        {  i32 i64 u32 -> u32 } read = "C";
+        // status
+        {  i32 -> i32 } _exit = "C";
+        // addr len prot flags fd  off -> void*
+        {  i64  i64 i32  i32   i32 i32 -> i64 } mmap = "C";
+        // mmap flags
+        i32 PROT_EXEC = 4;
+        i32 PROT_READ = 1;
+        i32 PROT_WRITE= 2;
+        i32 PROT_NONE = 0;
+        i32 MAP_PRIVATE = 2;
+        i32 MAP_ANON = 32;
+    };
+    struct ary {
+        val copy = { u8[] dst, int doff, u8[~] src, int soff, int len ->
+            for( int i=0; i<len; i++ )
+                dst[i+doff] = src[i+soff];
+            return dst;
+        };
+    };
+    struct io {
+        // Print string to stdout
+        val p = { u8[~] str ->
+            i64 ptr = str;  // cast array base to i64
+            return sys.libc.write(1,ptr,str#);
+        };
+
+        // Return stdin as a u8[]
+        val stdin = { ->
+            var buf = new u8[8*1024];
+            i64 ptr = buf;
+            int len = 0;
+            while( true ) {
+                int rez = sys.libc.read(0,ptr,buf#);
+                if( rez < 0 ) sys.libc._exit(sys.libc.errno);
+                len += rez;
+                if( rez < buf# )
+                    break;
+                sys.libc._exit(-2); // Need to implement
+            }
+            // Compress
+            var dst = new u8[len];
+            return sys.ary.copy(dst,0,buf,0,len);
+        };
+    };
+};
diff --git a/src/test/java/com/seaofnodes/simple/BrainFuckTest.java b/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
index aa6fada0..9f626805 100644
--- a/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
+++ b/src/test/java/com/seaofnodes/simple/BrainFuckTest.java
@@ -20,7 +20,7 @@ public class BrainFuckTest {
         String brain_fuck = "Hello World!\n";
         TestC.run("brain_fuck", brain_fuck, 40);
 
-        EvalRisc5 R5 = TestRisc5.build("brain_fuck", 0, 146, false);
+        EvalRisc5 R5 = TestRisc5.build("brain_fuck", 0, 28, false);
         int trap = R5.step(100000);
         assertEquals(0,trap);
         int ptr = (int)R5.regs[riscv.A0];
@@ -28,7 +28,7 @@ public class BrainFuckTest {
         for( int i=0; i<brain_fuck.length(); i++ )
             assertEquals(brain_fuck.charAt(i), R5.ld1z(ptr+4+i));
 
-        EvalArm64 A5 = TestArm64.build("brain_fuck", 0, 34, false);
+        EvalArm64 A5 = TestArm64.build("brain_fuck", 0, 28, false);
         int trap_arm = A5.step(100000);
         assertEquals(0,trap_arm);
         assertEquals(0,trap);
diff --git a/src/test/java/com/seaofnodes/simple/Chapter01Test.java b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
index cddbdfcf..ac9adacc 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter01Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter01Test.java
@@ -25,9 +25,9 @@ public class Chapter01Test {
     public void testZero() {
         CodeGen code = new CodeGen("return 0;");
         code.parse();
-        for( Node use : code._start._outputs )
-            if( use instanceof ConstantNode con && con._type instanceof TypeInteger )
-                assertEquals(TypeInteger.constant(0),con._type);
+        Node use = code.expr();
+        if( use instanceof ConstantNode con && con._type instanceof TypeInteger )
+            assertEquals(TypeInteger.constant(0),con._type);
     }
 
     @Test
diff --git a/src/test/java/com/seaofnodes/simple/Chapter09Test.java b/src/test/java/com/seaofnodes/simple/Chapter09Test.java
index 401f346f..551880b1 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter09Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter09Test.java
@@ -128,14 +128,14 @@ while(v1+arg) {
 }
                 """);
         code.parse().opto();
-        assertEquals("return 0;", code.print());
+        assertEquals("Stop[ ]", code.print()); // No explicit return: omit default main.
     }
 
     @Test
     public void testWhile0() {
-        CodeGen code = new CodeGen("while(0) continue; if(0) arg=0;");
+        CodeGen code = new CodeGen("while(0) continue; if(0) arg=0; return arg;");
         code.parse().opto();
-        assertEquals("return 0;", code.print());
+        assertEquals("return arg;", code.print());
     }
 
     @Test
@@ -145,6 +145,7 @@ if(0) while(0) {
     int arg=arg;
     while(0) {}
 }
+return 0;
 """);
         code.parse().opto();
         assertEquals("return 0;", code.print());
@@ -209,7 +210,7 @@ return -0+0+0;
     public void testFuzz3() {
         CodeGen code = new CodeGen("int v0=0; while(0==69) while(v0) return 0;");
         code.parse().opto();
-        assertEquals("return 0;", code.print());
+        assertEquals("Stop[ ]", code.print()); // The only return is unreachable.
     }
 
     @Test
@@ -255,7 +256,7 @@ while(0==1) while(v0)
         v0=1+v0;
 """);
         code.parse().opto();
-        assertEquals("return 0;", code.print());
+        assertEquals("Stop[ ]", code.print());
     }
 
     @Test
diff --git a/src/test/java/com/seaofnodes/simple/Chapter10Test.java b/src/test/java/com/seaofnodes/simple/Chapter10Test.java
index 91505f41..bcb73eb9 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter10Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter10Test.java
@@ -362,6 +362,7 @@ if(0) {
         v0=v2;
     }
 }
+return 0;
    """);
         code.parse().opto();
         assertEquals("return 0;", code.print());
@@ -436,6 +437,7 @@ while(0) {}
             }
         }    }
 }
+return 0;
 """);
         code.parse().opto();
         assertEquals("return 0;", code.print());
diff --git a/src/test/java/com/seaofnodes/simple/Chapter12Test.java b/src/test/java/com/seaofnodes/simple/Chapter12Test.java
index 0b4ad8ec..d8b072a2 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter12Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter12Test.java
@@ -132,15 +132,15 @@ return n.i;
 
     @Test
     public void testNullRef4() {
-        CodeGen code = new CodeGen("-null-5/null-5;");
+        CodeGen code = new CodeGen("return -null-5/null-5;");
         try { code.parse().opto().typeCheck(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot 'Add' null",e.getMessage()); }
+        catch( Exception e ) { assertEquals("Cannot '+' null",e.getMessage()); }
     }
 
     @Test public void testNullRef5() {
         CodeGen code = new CodeGen("return null+42;");
         try { code.parse().opto().typeCheck(); fail(); }
-        catch( Exception e ) { assertEquals("Cannot 'Add' null",e.getMessage()); }
+        catch( Exception e ) { assertEquals("Cannot '+' null",e.getMessage()); }
     }
 
     @Test
@@ -148,6 +148,7 @@ return n.i;
         CodeGen code = new CodeGen(
 """
 struct S{};
+return 0;
 """);
         code.parse().opto();
         assertEquals("return 0;", code.print());
diff --git a/src/test/java/com/seaofnodes/simple/Chapter14Test.java b/src/test/java/com/seaofnodes/simple/Chapter14Test.java
index f0fe7dcd..c342eeed 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter14Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter14Test.java
@@ -176,7 +176,7 @@ while(v1) break;
 return v1;
 """);
         code.parse().opto();
-        assertEquals("return (Phi(Loop,((1<<arg)&1),0)&Phi(Loop,Shl,4294967295));", code.print());
+        assertEquals("return Phi(Loop,(((1<<arg)&1)&Shl),0);", code.print());
         assertEquals("1", Eval2.eval(code,  0));
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter15Test.java b/src/test/java/com/seaofnodes/simple/Chapter15Test.java
index cb92277f..074cd8ba 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter15Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter15Test.java
@@ -255,10 +255,10 @@ return new flt;
     public void testBad1() {
         CodeGen code = new CodeGen(
 """
-int is = new int[2];
+flt is = new int[2];
 """);
         try { code.parse().opto(); fail(); }
-        catch( Exception e ) { assertEquals("Type *[int] is not of declared type int",e.getMessage()); }
+        catch( Exception e ) { assertEquals("Type *[int] is not of declared type flt",e.getMessage()); }
     }
 
     @Test
@@ -325,6 +325,7 @@ while(0) {}
 u32 v7=0;
 int v8=0;
 while(0<--1>>>---(v7*0==v8)) {}
+return 0;
 """);
         code.parse().opto();
         assertEquals("return 0;", code.print());
@@ -349,6 +350,7 @@ else {
             }
         }
 }
+return 0;
 """);
         code.parse().opto();
         assertEquals("return 0;", code.print());
diff --git a/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index 7c0af028..6eb4d6f4 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -140,7 +140,7 @@ while(arg--) {
 }
 return a;
 """);
-        code.parse().opto().typeCheck().GCM();
+        code.parse().opto().typeCheck();
         assertEquals("return Phi(Loop,1,Phi(Loop,2,Phi_a));", code._stop.toString());
         assertEquals("1", Eval2.eval(code,  0));
         assertEquals("2", Eval2.eval(code,  1));
@@ -185,7 +185,7 @@ var sq = { int x ->
 return sq(arg)+sq(3);
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return (#2+#2); return (Parm_x(sq,int)*x); ]", code._stop.toString());
+        assertEquals("Stop[ return (Parm_x(sq,int)*x); return (#2+#2); ]", code._stop.toString());
         assertEquals("13", Eval2.eval(code, 2));
     }
 
@@ -223,7 +223,7 @@ var fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
 return fcn(3);
 """);
         code.parse().opto();
-        assertEquals("Stop[ return #2; return (Parm_x($fun1,int,3)*x); return (Parm_x($fun2,int,3)<<1); ]", code._stop.toString());
+        assertEquals("Stop[ return (Parm_x($fun2,int,3)<<1); return (Parm_x($fun1,int,3)*x); return #2; ]", code._stop.toString());
         assertEquals("6", Eval2.eval(code, 0));
         assertEquals("9", Eval2.eval(code, 1));
     }
@@ -233,7 +233,7 @@ return fcn(3);
     public void testFcn5() {
         CodeGen code = new CodeGen("val fact = { int x -> x <= 1 ? 1 : x*fact(x-1); }; return fact(arg);");
         code.parse().opto().typeCheck();
-        assertEquals("Stop[ return #2; return Phi(Region,1,(Parm_x(fact,int,arg,(x-1))*#2)); ]", code._stop.toString());
+        assertEquals("Stop[ return Phi(Region,1,(Parm_x(fact,int,arg,(x-1))*#2)); return #2; ]", code._stop.toString());
         assertEquals( "1", Eval2.eval(code, 0));
         assertEquals( "1", Eval2.eval(code, 1));
         assertEquals( "2", Eval2.eval(code, 2));
@@ -265,7 +265,7 @@ val g = {->2;};
 return 2;
 """);
         code.parse().opto().typeCheck().GCM();
-        assertEquals("Stop[ return 1; return 1; return 2; ]", code._stop.toString());
+        assertEquals("Stop[ return 2; return 1; return 1; ]", code._stop.toString());
         assertEquals("1", Eval2.eval(code,  0));
     }
 
@@ -283,7 +283,7 @@ for(;;) {
 }
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return #2; return Parm_i(x,int); ]", code._stop.toString());
+        assertEquals("Stop[ return Parm_i(x,int); return #2; ]", code._stop.toString());
         assertEquals("3", Eval2.eval(code,  0));
     }
 
@@ -321,7 +321,7 @@ val fcn = { !Person?[] !ps, int x ->
 var ps = new !Person?[2];
 ps[0] = new Person;
 ps[1] = new Person;
-fcn(ps,1);
+return fcn(ps,1);
 """);
         code.driver(Phase.LocalSched);
         assertEquals("return 0;", code._stop.toString());
@@ -356,6 +356,7 @@ for(;;) {
     if (i2i(2) == arg) break;
     i2i = null;
 }
+return 0;
 """);
         try { code.parse().opto().typeCheck(); fail(); }
         catch( Exception e ) { assertEquals("Might be null calling { int -> int #1}?",e.getMessage()); }
@@ -454,7 +455,7 @@ if (i2i) return i2i(arg);
 return f2f(o)(1);
 """);
         code.driver(Phase.LocalSched);
-        assertEquals("Stop[ return Phi(Region,#2,1); return Parm_i(o,int); ]", code._stop.toString());
+        assertEquals("Stop[ return Parm_i(i2i.o,int); return Phi(Region,#2,1); ]", code._stop.toString());
         assertEquals("1", Eval2.eval(code,  2));
     }
 
diff --git a/src/test/java/com/seaofnodes/simple/Chapter19Test.java b/src/test/java/com/seaofnodes/simple/Chapter19Test.java
index c53a8e11..4564e513 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter19Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter19Test.java
@@ -22,7 +22,7 @@ public class Chapter19Test {
         con.toString();
         org.junit.Assert.assertNull(call.name());
 
-        var fun = new FunNode(null,tfp);
+        var fun = new FunNode(null,tfp,"printerTarget");
         fun._name = "printerTarget";
         fun.addDef(code._start);
         code.link(fun);
@@ -295,6 +295,7 @@ for( int i=0; i<A#; i++ )
     A[i] = i;
 for( int i=0; i<A#; i++ )
     B[i] += A[i];
+return 0;
 """);
         code.driver(Phase.LocalSched,"x86_64_v2", "SystemV");
         assertEquals("return 0;", code.print());
@@ -339,7 +340,7 @@ val fcn = arg ? { int x -> x*x; } : { int x -> x+x; };
 return fcn(2)*10 + fcn(3);
 """);
         code.driver(Phase.LocalSched,"x86_64_v2", "SystemV");
-        assertEquals("Stop[ return (add,#2,(muli,#2)); return (mul,Parm_x($fun1,int),x); return (shli,Parm_x($fun2,int)); ]", code.print());
+        assertEquals("Stop[ return (shli,Parm_x($fun2,int)); return (mul,Parm_x($fun1,int),x); return (add,#2,(muli,#2)); ]", code.print());
     }
 
     @Test
@@ -350,7 +351,7 @@ val sq = { int x -> x*x; };
 return sq(arg) + sq(3);
 """);
         code.driver(Phase.LocalSched,"x86_64_v2", "SystemV");
-        assertEquals("Stop[ return (add,#2,#2); return (mul,Parm_x(sq,int),x); ]", code.print());
+        assertEquals("Stop[ return (mul,Parm_x(sq,int),x); return (add,#2,#2); ]", code.print());
     }
 
     @Test public void testSelectedMemory() {
diff --git a/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index e63fb32e..3575e461 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -1,5 +1,7 @@
 package com.seaofnodes.simple;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
+
 
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.print.ASMPrinter;
@@ -76,6 +78,7 @@ return f(s);
 
 
     @org.junit.Rule public final org.junit.rules.ErrorCollector _errors = new org.junit.rules.ErrorCollector();
+
     @Test public void testAllocatorMasks() { com.seaofnodes.simple.codegen.RegAllocTestSupport.masks(); }
     @Test public void testAllocatorUnion() { com.seaofnodes.simple.codegen.RegAllocTestSupport.union(); }
     @Test public void testAllocatorCopyClobber() throws Exception { com.seaofnodes.simple.codegen.RegAllocTestSupport.copyClobber(); }
@@ -104,9 +107,8 @@ return f(s);
     }
 
     static void testCPU(String src, String cpu, String os, int spills, String stop) {
-        CodeGen code = new CodeGen(src);
+        CodeGen code = new CheckedCodeGen(src);
         code.driver(CodeGen.Phase.RegAlloc,cpu,os);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
         SpillStats.record(code,"Chapter20",cpu,os);
         SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
         if( stop!=null ) assertEquals(stop,code._stop.toString());
@@ -146,7 +148,7 @@ val sqrt = { int x ->
 };
 return sqrt(arg) + sqrt(arg+2);
 """;
-        testTarget(src,"x86_64_v2", "SystemV",23,null);
+        testTarget(src,"x86_64_v2", "SystemV",40,null);
         testTarget(src,"riscv"    , "SystemV",17,null);
         testTarget(src,"arm"      , "SystemV",18,null);
     }
@@ -175,9 +177,9 @@ return sqrt(farg) + sqrt(farg+2.0);
     @Test
     public void testAlloc2() {
         String src = "int[] !xs = new int[3]; xs[arg]=1; return xs[arg&1];";
-        testTarget(src,"x86_64_v2","SystemV",4,"return .[];");
-        testTarget(src,"riscv","SystemV",8,"return .[];");
-        testTarget(src,"arm","SystemV",9,"return .[];");
+        testTarget(src,"x86_64_v2","SystemV",3,"return .[];");
+        testTarget(src,"riscv","SystemV",6,"return .[];");
+        testTarget(src,"arm","SystemV",6,"return .[];");
     }
 
     @Test
@@ -193,7 +195,7 @@ for( int i=0; i<ary#-1; i++ )
     ary[i+1] += ary[i];
 return ary[1] * 1000 + ary[3]; // 1 * 1000 + 6
 """;
-        testTarget(src,"x86_64_v2", "SystemV",7,"return .[];");
+        testTarget(src,"x86_64_v2", "SystemV",5,"return .[];");
         testTarget(src,"riscv"    , "SystemV",7,"return (add,.[],(mul,.[],1000));");
         testTarget(src,"arm"      , "SystemV",5,"return (add,.[],(mul,.[],1000));");
     }
@@ -236,9 +238,14 @@ s.cs[0] =  67; // C
 s.cs[1] = 108; // l
 hashCode(s);
 """;
-        testTarget(src,"x86_64_v2", "SystemV",15,null);
-        testTarget(src,"riscv"    , "SystemV", 10,null);
-        testTarget(src,"arm"      , "SystemV", 10,null);
+        // Without an explicit return, default main must be removed completely.
+        // Seed 0 previously left a loop with a missing branch successor.
+        for( String cpu : new String[]{"x86_64_v2","riscv","arm"} )
+            new CodeGen(src,com.seaofnodes.simple.type.TypeInteger.BOT,0)
+                .driver(CodeGen.Phase.Encoding,cpu,"SystemV");
+        testTarget(src,"x86_64_v2", "SystemV",0,null);
+        testTarget(src,"riscv"    , "SystemV",1,null);
+        testTarget(src,"arm"      , "SystemV",0,null);
     }
 
     @Test
@@ -339,8 +346,8 @@ for( int pc = 0; pc < program#; pc++ ) {
 return output;
 """;
         testTarget(src,"x86_64_v2", "SystemV",40,null);
-        testTarget(src,"riscv"    , "SystemV",146,null);
-        testTarget(src,"arm"      , "SystemV",34,null);
+        testTarget(src,"riscv"    , "SystemV",28,null);
+        testTarget(src,"arm"      , "SystemV",28,null);
         //assertEquals("Hello World!\n", Eval2.eval(code, 0, 10000));
     }
     // Original Chapter 20 allocation workload, kept fixed for cohort comparisons.
diff --git a/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java b/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java
index bc300217..b81483d8 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter21AllocTest.java
@@ -21,7 +21,7 @@ val sqrt = { int x ->
 };
 return sqrt(arg) + sqrt(arg+2);
 """;
-        Chapter21Test.testCPU(src,"x86_64_v2", "Win64"  ,23,null);
+        Chapter21Test.testCPU(src,"x86_64_v2", "Win64"  ,40,null);
         Chapter21Test.testCPU(src,"riscv"    , "SystemV",19,null);
         Chapter21Test.testCPU(src,"arm"      , "SystemV",19,null);
     }
diff --git a/src/test/java/com/seaofnodes/simple/Chapter21Test.java b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
index a51ae3bc..2c91de0d 100644
--- a/src/test/java/com/seaofnodes/simple/Chapter21Test.java
+++ b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
@@ -4,6 +4,7 @@ import com.seaofnodes.isa.eval.EvalRisc5;
 
 import com.seaofnodes.isa.eval.EvalArm64;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.cpus.arm.arm;
 import com.seaofnodes.simple.node.cpus.riscv.riscv;
@@ -103,39 +104,6 @@ public class Chapter21Test {
     }
 
 
-    @Test public void testNarrowStores() throws IOException {
-        for( String type : new String[]{"i8","u8","i16","u16"} ) {
-            String src = "struct S { "+type+" x; }; !S !s = new S; s.x = arg; return 0;";
-            CodeGen code = new CodeGen(src).driver("riscv","SystemV",null);
-            int stores=0;
-            for( var bb : code._cfg )
-                for( var node : bb.outs() )
-                    if( node instanceof com.seaofnodes.simple.node.cpus.riscv.StoreRISC st ) {
-                        stores++;
-                        assertEquals("Byte/short stores have no FP encoding",-1,st.regmap(4).nextReg((short)31));
-                    }
-            assertEquals(1,stores);
-            byte[] image = new byte[1<<20];
-            byte[] bits = code._encoding.bits();
-            System.arraycopy(bits,0,image,0,bits.length);
-            EvalRisc5 cpu = new EvalRisc5(image,1<<16);
-            cpu.regs[riscv.A0] = 0x8765;
-            assertEquals(0,cpu.step(100));
-            assertEquals(type.endsWith("8") ? 0x65 : 0x8765,
-                         type.endsWith("8") ? cpu.ld1z(1<<16) : cpu.ld2z(1<<16));
-            code = new CodeGen(src).driver(CodeGen.Phase.Encoding,"x86_64_v2",TestC.CALL_CONVENTION);
-            stores=0;
-            for( var bb : code._cfg )
-                for( var node : bb.outs() )
-                    if( node instanceof com.seaofnodes.simple.node.cpus.x86_64_v2.StoreX86 st ) {
-                        stores++;
-                        assertEquals("Byte/short stores have no XMM encoding",-1,st.regmap(4).nextReg((short)15));
-                    }
-            assertEquals(1,stores);
-        }
-    }
-
-
     @Test public void testArmCallInstructions() {
         EvalArm64 cpu = new EvalArm64(new byte[512],256);
         for( int delta : new int[]{4,32,-4} ) {
@@ -238,6 +206,52 @@ public class Chapter21Test {
     }
 
 
+    @Test public void testNarrowStores() throws IOException {
+        for( String type : new String[]{"i8","u8","i16","u16"} ) {
+            String src = "struct S { "+type+" x; }; !S !s = new S; s.x = arg; return 0;";
+            CodeGen code = new CodeGen(src).driver("riscv","SystemV",null);
+            int stores=0;
+            for( var bb : code._cfg )
+                for( var node : bb.outs() )
+                    if( node instanceof com.seaofnodes.simple.node.cpus.riscv.StoreRISC st ) {
+                        stores++;
+                        assertEquals("Byte/short stores have no FP encoding",-1,st.regmap(4).nextReg((short)31));
+                    }
+            assertEquals(1,stores);
+            byte[] image = new byte[1<<20];
+            byte[] bits = code._encoding.bits();
+            System.arraycopy(bits,0,image,0,bits.length);
+            EvalRisc5 cpu = new EvalRisc5(image,1<<16);
+            cpu.regs[riscv.A0] = 0x8765;
+            assertEquals(0,cpu.step(100));
+            assertEquals(type.endsWith("8") ? 0x65 : 0x8765,
+                         type.endsWith("8") ? cpu.ld1z(1<<16) : cpu.ld2z(1<<16));
+            code = new CodeGen(src).driver(CodeGen.Phase.Encoding,"x86_64_v2",TestC.CALL_CONVENTION);
+            stores=0;
+            for( var bb : code._cfg )
+                for( var node : bb.outs() )
+                    if( node instanceof com.seaofnodes.simple.node.cpus.x86_64_v2.StoreX86 st ) {
+                        stores++;
+                        assertEquals("Byte/short stores have no XMM encoding",-1,st.regmap(4).nextReg((short)15));
+                    }
+            assertEquals(1,stores);
+        }
+    }
+
+    @Test public void testNativeExitStatus() throws IOException {
+        Path source = Path.of("build/objs/nativeExit.c");
+        Files.createDirectories(source.getParent());
+        Files.writeString(source,"int main() { return 7; }\n");
+        try {
+            TestC.gcc(source.toString(),null,null,false,
+                      "build/objs/nativeExit"+(TestC.OS.startsWith("Windows") ? ".exe" : ""));
+        } catch( AssertionError error ) {
+            assertTrue(error.getMessage(),error.getMessage().contains("Program exit status"));
+            return;
+        }
+        fail("A failing native program must fail the test, even with empty stdout");
+    }
+
     @Test public void testCoalescing() { com.seaofnodes.simple.codegen.RegAllocTestSupport.coalescing(); }
     @Test public void testCopyForward() throws Exception { com.seaofnodes.simple.codegen.RegAllocTestSupport.copyForward(); }
     @Test public void testRisc64BitStore() {
@@ -278,8 +292,7 @@ public class Chapter21Test {
     }
 
     static void testCPU( String src, String cpu, String os, int spills, String stop ) {
-        CodeGen code = new CodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
+        CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
         SpillStats.record(code,"Chapter21",cpu,os);
         SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
         if( stop != null )
@@ -422,7 +435,7 @@ public class Chapter21Test {
 
     @Test public void testPerson() throws IOException {
         String person = "6\n";
-        TestC.run("person", person, 0);
+        TestC.run("person21", person, 0);
 
         // Memory layout starting at PS:
         int ps = 1<<16;         // Person array pointer starts at heap start
@@ -433,7 +446,7 @@ public class Chapter21Test {
         int p1 = ps+4*8+1*8;
         // P2 = { age } // sizeof=8
         int p2 = ps+4*8+2*8;
-        EvalRisc5 R5 = TestRisc5.build("person", ps, 0, false);
+        EvalRisc5 R5 = TestRisc5.build("person21", ps, 0, false);
         R5.regs[riscv.A1] = 1;  // Index 1
         R5.st8(ps,3);           // Length
         R5.st8(ps+1*8,p0);
@@ -449,7 +462,7 @@ public class Chapter21Test {
         assertEquals(17+1,R5.ld8(p1));
         assertEquals(60+0,R5.ld8(p2));
 
-        EvalArm64 A5 = TestArm64.build("person", ps, 0, false);
+        EvalArm64 A5 = TestArm64.build("person21", ps, 0, false);
         A5.regs[arm.X1] = 1;  // Index 1
         A5.st8(ps, 3);
         A5.st8(ps+1*8,p0);
diff --git a/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/src/test/java/com/seaofnodes/simple/Chapter22Test.java
new file mode 100644
index 00000000..2d94b8f0
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -0,0 +1,411 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.isa.eval.EvalRisc5;
+
+import com.seaofnodes.isa.eval.EvalArm64;
+
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
+import com.seaofnodes.simple.codegen.CodeGen;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+import com.seaofnodes.simple.node.cpus.arm.arm;
+import com.seaofnodes.simple.node.cpus.riscv.riscv;
+import org.junit.Ignore;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class Chapter22Test {
+
+    @Test public void testNarrowCReturnsEmulated() {
+        String[] types = {"i8","u8","i16","u16","i32","u32","int"};
+        long[] values = {0xa5a5a5a500000000L,0xa5a5a5a50000007fL,0xa5a5a5a500000080L,
+            0xa5a5a5a500007fffL,0xa5a5a5a500008000L,0xa5a5a5a57fffffffL,
+            0xa5a5a5a580000000L,0xa5a5a5a5ffffffffL};
+        for( String target : new String[]{"arm","riscv"} )
+            for( int i=0; i<types.length; i++ ) {
+                String src = "{"+types[i]+"} c_narrow=\"C\"; return c_narrow();";
+                CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,target,"SystemV");
+                var enc = code._encoding;
+                // Link the external call to a tiny independent native stub.
+                var call = code._stop.walk(n -> n instanceof com.seaofnodes.simple.node.CallNode ? n : null);
+                int start = enc._opStart[call._nid];
+                ((com.seaofnodes.simple.codegen.RIPRelSize)call).patch(enc,start,enc._opLen[call._nid],0x1000-start);
+                for( long value : values ) {
+                    long expected = switch(i) {
+                    case 0 -> (byte)value; case 1 -> value&255;
+                    case 2 -> (short)value; case 3 -> value&65535;
+                    case 4 -> (int)value; case 5 -> value&0xffffffffL;
+                    default -> value;
+                    };
+                    byte[] image = new byte[1<<16];
+                    byte[] bits = enc.bits();
+                    System.arraycopy(bits,0,image,0,bits.length);
+                    if( target.equals("arm") ) {
+                        EvalArm64 cpu = new EvalArm64(image,1<<15);
+                        // MOVZ X0,0x1100; LDR X0,[X0]; RET X30.
+                        cpu._pc = enc._opStart[code.link(code._main)._nid];
+                        cpu.st4(0x1000,0xd2822000); cpu.st4(0x1004,0xf9400000);
+                        cpu.st4(0x1008,0xd65f03c0);
+                        cpu.st8(0x1100,value);
+                        assertEquals(0,cpu.step(1000));
+                        assertEquals(0,cpu._pc);
+                        assertEquals(types[i],expected,cpu.regs[0]);
+                    } else {
+                        EvalRisc5 cpu = new EvalRisc5(image,1<<15);
+                        // AUIPC a0,0; LD a0,12(a0); RET.
+                        cpu._pc = enc._opStart[code.link(code._main)._nid];
+                        cpu.st4(0x1000,0x00000517); cpu.st4(0x1004,0x00c53503);
+                        cpu.st4(0x1008,0x00008067);
+                        // RV64 widens even u32 returns by sign-extending bit 31.
+                        cpu.st8(0x100c,i==6 ? value : (int)expected);
+                        assertEquals(0,cpu.step(1000));
+                        assertEquals(0,cpu._pc);
+                        assertEquals(types[i],expected,cpu.regs[riscv.A0]);
+                    }
+                }
+            }
+    }
+
+    @Test public void testNarrowCReturns() throws IOException {
+        String src = """
+            {i8} c_i8="C"; {u8} c_u8="C";
+            {i16} c_i16="C"; {u16} c_u16="C";
+            {i32} c_i32="C"; {u32} c_u32="C";
+            {int} c_i64="C";
+            val test_i8={->return c_i8();};
+            val test_u8={->return c_u8();};
+            val test_i16={->return c_i16();};
+            val test_u16={->return c_u16();};
+            val test_i32={->return c_i32();};
+            val test_u32={->return c_u32();};
+            val test_i64={->return c_i64();};
+            val test_cmp={->return c_i32()==-1;};
+            """;
+        for( String conv : new String[]{"SystemV","Win64"} )
+            TestC.run(src,conv,conv.equals("SystemV") ? "sysv_abi" : "ms_abi",
+                      "src/test/java/com/seaofnodes/simple/progs/c_returns.c",
+                      "build/objs/c_returns"+conv,"S","",-1);
+    }
+
+
+
+    @Test public void testReturnedFunctions() throws IOException {
+        for( String src : new String[]{"return {->42;};", "val f={->42;}; return f;", "return sys.io.p;"} )
+            for( String target : new String[]{"riscv","arm"} ) {
+                CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,target,"SystemV").exportELF(null);
+                byte[] image = new byte[1<<16];
+                byte[] bits = code._encoding.bits();
+                System.arraycopy(bits,0,image,0,bits.length);
+                boolean library = src.contains("sys.io.p");
+                // u8[]: four-byte length followed by its bytes.
+                image[0x2000]=2; image[0x2004]='o'; image[0x2005]='k';
+                int entry = code._encoding._opStart[code.link(code._main)._nid];
+                if( target.equals("riscv") ) {
+                    EvalRisc5 cpu = new EvalRisc5(image,1<<15);
+                    cpu._pc = entry;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    cpu._pc = (int)cpu.regs[riscv.A0]; // Call the returned address.
+                    cpu.regs[riscv.A0] = 0x2000;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    if( library ) assertEquals("ok",cpu._stdout.toString());
+                    else assertEquals(42,cpu.regs[riscv.A0]);
+                } else {
+                    EvalArm64 cpu = new EvalArm64(image,1<<15);
+                    cpu._pc = entry;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    cpu._pc = (int)cpu.regs[0];
+                    cpu.regs[0] = 0x2000;
+                    assertEquals(0,cpu.step(1000));
+                    assertEquals(0,cpu._pc);
+                    if( library ) assertEquals("ok",cpu._stdout.toString());
+                    else assertEquals(42,cpu.regs[0]);
+                }
+            }
+        CodeGen unused = new CodeGen("({->42;}); return 0;").parse().opto();
+        assertEquals(1,unused._stop.nIns());
+    }
+
+    @Test public void testReturnedFunctionsNative() throws IOException {
+        String src = "val factory={int x -> if(x) return {->42;}; return {->43;};}; val printer={->return sys.io.p;};";
+        String obj = "build/objs/funptr.o";
+        new CheckedCodeGen(src).driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,obj);
+        assertEquals("ok",TestC.gcc(obj,"","src/test/java/com/seaofnodes/simple/progs/funptr.c",false,
+                                   "build/objs/funptr"+(TestC.OS.startsWith("Windows") ? ".exe" : "")));
+    }
+
+    @Test public void testRiscvRightShifts() {
+        // SRAI, SRLI, SRA, SRL: a0 = -32 shifted by 4.
+        int[] ops = {0x40455513,0x00455513,0x40b55533,0x00b55533};
+        for( int i=0; i<ops.length; i++ ) {
+            EvalRisc5 r5 = new EvalRisc5(new byte[1<<16],1<<15);
+            r5.st4(0,ops[i]);
+            r5.regs[riscv.A0] = -32;
+            r5.regs[riscv.A0+1] = 4;
+            assertEquals(0,r5.step(1));
+            assertEquals((i&1)==0 ? -2L : 0x0fff_ffff_ffff_fffeL,r5.regs[riscv.A0]);
+        }
+    }
+
+    @Test public void testRiscvPointerRelocation() {
+        CodeGen code = new CheckedCodeGen("return \"x\";").driver(CodeGen.Phase.Encoding,"riscv","SystemV");
+        var enc = code._encoding;
+        assertEquals(1,enc._bigCons.size());
+        var ptr = (com.seaofnodes.simple.node.cpus.riscv.TMPRISC)enc._bigCons.keySet().iterator().next();
+        int start = enc._opStart[ptr._nid];
+        for( int delta : new int[]{0x7ff,0x800,0xfff,0x1000,0x1800,-1,-0x800,-0x801} ) {
+            ptr.patch(enc,start,enc._opLen[ptr._nid],delta);
+            // Place the program above zero so backward targets are valid addresses.
+            byte[] image = new byte[1<<16];
+            System.arraycopy(enc.bits(),0,image,0x4000,enc._bits.size());
+            EvalRisc5 r5 = new EvalRisc5(image,1<<15);
+            r5._pc = 0x4000;
+            assertEquals(0,r5.step(100));
+            assertEquals(0x4000+start+delta,r5.regs[riscv.A0]);
+        }
+    }
+
+    @Test public void testSubZeroTypeError() {
+        try {
+            new CodeGen("return null-0;").parse().opto().typeCheck();
+            fail("Subtraction must reject null even when the other operand is zero");
+        } catch( Parser.ParseException e ) {
+            assertEquals("Cannot '-' null",e.getMessage());
+        }
+    }
+
+    @Test public void testInfiniteReturn() {
+        String src = "struct S { int i; }; !S !s = new S; while(1) s.i++; return s.i;";
+        testCPU(src,"x86_64_v2","SystemV",0,"return Top;");
+        testCPU(src,"riscv","SystemV",0,"return Top;");
+        testCPU(src,"arm","SystemV",0,"return Top;");
+    }
+
+
+    @Test @Ignore
+    public void testJig() throws IOException {
+        String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/jig.smp"));
+        //String src = Files.readString(Path.of("docs/examples/BubbleSort.smp"));
+        testCPU(src,"x86_64_v2", "Win64"  ,-1,null);
+        testCPU(src,"riscv"    , "SystemV",-1,null);
+        testCPU(src,"arm"      , "SystemV",-1,null);
+    }
+
+    static CodeGen testCPU( String src, String cpu, String os, int spills, String stop ) {
+        CodeGen code = new CheckedCodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
+        SpillStats.record(code,"Chapter22",cpu,os);
+        SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
+        if( stop != null )
+            assertEquals(stop, code._stop.toString());
+        return code;
+    }
+
+
+    static int testCPUSize( String src, String cpu, String os, int spills, String stop ) {
+        return testCPU(src,cpu,os,spills,stop)._encoding._bits.size();
+    }
+
+    // Should not fold away
+    @Test public void testSextFail() throws IOException {
+        String src = """
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age = (arg<<17)>>17;
+return 0;
+""";
+        assertEquals(46, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(60, testCPUSize(src, "riscv","SystemV",4,"return 0;"));
+        assertEquals(56, testCPUSize(src, "arm","SystemV",4,"return 0;"));
+
+        // do assertEquals here
+        EvalRisc5 R5 = TestRisc5.build("sext_str_not_fold_away", 0, 4, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_not_fold_away", 0, 4, false);
+        trap = A5.step(100);
+        assertEquals(0,trap);
+
+    }
+
+    // Should not fold away
+    @Test public void testSextFail2() throws IOException {
+        String src = """
+
+                struct Person { i32 age;};
+                !Person !p = new Person;
+                p.age = (arg<<48)>>48;
+                return 0;
+        """;
+
+        EvalRisc5 R5 = TestRisc5.build("sext_str_not_fold_away_2", 0, 4, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_not_fold_away_2", 0, 4, false);
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+
+        assertEquals(46, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(60, testCPUSize(src, "riscv","SystemV",4,"return 0;"));
+        assertEquals(56, testCPUSize(src, "arm","SystemV",4,"return 0;"));
+
+    }
+
+    // Should fold away
+    @Test public void testSextSuccess() throws IOException {
+        String src = """
+// Should fold away sign extend
+struct Person { i8 age;};
+!Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
+       """;
+
+        EvalRisc5 R5 = TestRisc5.build("sext_str_fold_away", 0, 5, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_fold_away", 0, 5, false);
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+
+        assertEquals(41, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(56, testCPUSize(src, "riscv","SystemV",5,"return 0;"));
+        assertEquals(52, testCPUSize(src, "arm","SystemV",5,"return 0;"));
+        // do assertEquals here
+    }
+
+
+    // Int now is changed to 4 bytes.
+    @Test public void testPerson() throws IOException {
+        String person = "6\n";
+        TestC.run("person", person, 0);
+
+        // Memory layout starting at PS:
+        int ps = 1<<16;         // Person array pointer starts at heap start
+        // Person[3] = { len,pad,P0,P1,P2 }; // sizeof = 4*8
+        // P0 = { age } // sizeof=8
+        int p0 = ps+4*8+0*8;
+        // P1 = { age } // sizeof=8
+        int p1 = ps+4*8+1*8;
+        // P2 = { age } // sizeof=8
+        int p2 = ps+4*8+2*8;
+        EvalRisc5 R5 = TestRisc5.build("person", ps, 0, false);
+        R5.regs[riscv.A1] = 1;  // Index 1
+        R5.st8(ps,3);           // Length
+        R5.st8(ps+1*8,p0);
+        R5.st8(ps+2*8,p1);
+        R5.st8(ps+3*8,p2);
+        R5.st8(p0, 5); // age= 5
+        R5.st8(p1,17); // age=17
+        R5.st8(p2,60); // age=60
+
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+        assertEquals( 5+0,R5.ld8(p0));
+        assertEquals(17+1,R5.ld8(p1));
+        assertEquals(60+0,R5.ld8(p2));
+
+        EvalArm64 A5 = TestArm64.build("person", ps, 0, false);
+        A5.regs[arm.X1] = 1;  // Index 1
+        A5.st8(ps, 3);
+        A5.st8(ps+1*8,p0);
+        A5.st8(ps+2*8,p1);
+        A5.st8(ps+3*8,p2);
+        A5.st8(p0, 5); // age= 5
+        A5.st8(p1,17); // age=17
+        A5.st8(p2,60); // age=60
+
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+        assertEquals( 5+0, A5.ld8(p0));
+        assertEquals(17+1, A5.ld8(p1));
+        assertEquals(60+0, A5.ld8(p2));
+    }
+
+    @Test
+    public void testCoRecur() {
+        String src = """
+struct A { !B? !b; !C? !c; i64 ax; val az = x*2; };
+struct B { !A? !a; !C? !c; f32 bx; val bz = x*3; };
+struct C { !A? !a; !B? !b; f64 cx; val cz = x*x; };
+!A !aa = new A{ ax=17; };
+!B !bb = new B{ bx=3.14; a = aa; };
+!C !cc = new C{ cx=2.73; a = aa; b = bb; };
+aa.b = bb;
+aa.c = cc;
+bb.c = cc;
+val x = 5; // aa.az; // Error to self-define forward ref
+return cc.cz;
+""";
+        CodeGen code = new CodeGen(src).parse().opto().typeCheck();
+        assertEquals("return 25;", code._stop.toString());
+        assertEquals("25", Eval2.eval(code, 0));
+    }
+
+    @Test
+    public void testHelloWorld() throws IOException {
+        String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/helloWorld.smp"));
+        TestC.run(src,TestC.CALL_CONVENTION,null,null,"build/objs/helloWorld","","Hello, World!",0);
+
+        // Evaluate on RISC5 emulator
+        EvalRisc5 R5 = TestRisc5.build("helloWorld", 0, 2, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,R5.regs[riscv.A0]);
+        assertEquals("Hello, World!",R5._stdout.toString());
+
+        // Evaluate on ARM emulator
+        EvalArm64 arm = TestArm64.build("helloWorld", 0, 2, false);
+        trap = arm.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,arm.regs[0]);
+        assertEquals("Hello, World!",arm._stdout.toString());
+    }
+
+    @Test
+    public void testFinalArray() {
+        String src = """
+int N=4;
+i32[] !is = new i32[N];
+for( int i=0; i<N; i++ )
+    is[i] = i*i;
+val sum = { i32[~] is ->  // final array
+    int sum=0;
+    for( int i=0; i<is#; i++ )
+        sum += is[i];
+    return sum;
+};
+return sum(is);
+""";
+        CodeGen code = new CodeGen(src).parse().opto().typeCheck();
+        assertEquals("return Phi(Loop,0,(Phi_sum+.[]));", code._stop.toString());
+        assertEquals("14", Eval2.eval(code, 0));
+    }
+
+
+    @Test @Ignore
+    public void testEcho() throws IOException {
+        String src = Files.readString(Path.of("src/test/java/com/seaofnodes/simple/progs/echo.smp"));
+        TestC.run(src,TestC.CALL_CONVENTION,null,null,"build/objs/echo","","",0);
+
+        // Evaluate on RISC5 emulator
+        EvalRisc5 R5 = TestRisc5.build("echo", 0, 2, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,R5.regs[riscv.A0]);
+
+        // Evaluate on ARM emulator
+        EvalArm64 arm = TestArm64.build("echo", 0, 2, false);
+        trap = arm.step(100);
+        assertEquals(0,trap);
+        assertEquals(0,arm.regs[0]);
+    }
+
+
+}
diff --git a/src/test/java/com/seaofnodes/simple/Eval2.java b/src/test/java/com/seaofnodes/simple/Eval2.java
index a855350e..bbf88f1a 100644
--- a/src/test/java/com/seaofnodes/simple/Eval2.java
+++ b/src/test/java/com/seaofnodes/simple/Eval2.java
@@ -114,12 +114,10 @@ public abstract class Eval2 {
 
     public static String eval( CodeGen code, long arg ) { return eval(code,arg,1000); }
     public static String eval( CodeGen code, long arg, int timeout ) {
+        if( code._start.uctrl()==null ) return ""; // The empty program
         SB trace = null; // new SB(); // TRACE, set to null for off, new SB() for on
         // Force local scheduling phase
-        if( code._phase.ordinal() < CodeGen.Phase.TypeCheck .ordinal() )  code.typeCheck();
-        if( code._phase.ordinal() < CodeGen.Phase.LoopTree  .ordinal() )  code.loopTree();
-        if( code._phase.ordinal() < CodeGen.Phase.Schedule  .ordinal() )  code.GCM();
-        if( code._phase.ordinal() < CodeGen.Phase.LocalSched.ordinal() )  code.localSched();
+        code.driver(CodeGen.Phase.LocalSched);
         // Set global, so don't have to pass everywhere
         CODE = code;
 
@@ -300,9 +298,9 @@ public abstract class Eval2 {
     // Fetch without unboxing, searching up-Frame
     static Object val( Node n ) { return F.get(n); }
     // Fetch and unbox as primitive long
-    static long   x( Node n ) { Object d = F.get(n); return d==null ? 0 : (Long)  F.get(n);  }
+    static long   x( Node n ) { Object d = F.get(n); return d==null ? 0 : (Long)d;  }
     // Fetch and unbox as primitive double
-    static double d( Node n ) { Object d = F.get(n); return d==null ? 0 : (Double)F.get(n);  }
+    static double d( Node n ) { Object d = F.get(n); return d==null ? 0 : (Double)d;  }
     // Fetch and unbox a function constant
     static TypeFunPtr tfp(Node n) { return (TypeFunPtr)F.get(n); }
     // Fetch and unbox a closure
@@ -358,10 +356,19 @@ public abstract class Eval2 {
     }
 
     private static Object load( LoadNode ld ) {
-        TypeMemPtr tmp = (TypeMemPtr)ld.ptr()._type;
-        Object[] fs = (Object[])val(ld.ptr());
+        Object f = val(ld.ptr());
+        // Check for dense constant array
+        if( f instanceof TypeMemPtr tmp ) {
+            assert tmp._obj._con != TypeConAry.BOT;
+            if( ld._name.equals("#") )
+                return (long)tmp._obj._con.len();
+            int idx = offToIdx(x(ld.off()),tmp._obj);
+            return tmp._obj._con.at(idx);
+        }
+        Object[] fs = (Object[])f;
         if( ld._name.equals("#") )
             return (long)fs.length;
+        TypeMemPtr tmp = (TypeMemPtr)ld.ptr()._type;
         int idx = tmp._obj.isAry()
             ? offToIdx(x(ld.off()),tmp._obj)
             : tmp._obj.find(ld._name);
diff --git a/src/test/java/com/seaofnodes/simple/LiteralTest.java b/src/test/java/com/seaofnodes/simple/LiteralTest.java
new file mode 100644
index 00000000..2375f213
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/LiteralTest.java
@@ -0,0 +1,65 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.type.TypeConAryB;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.type.TypeMemPtr;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class LiteralTest {
+    private static final String[] ESCAPES = {"\\0", "\\n", "\\t", "\\r", "\\\\", "\\\"", "\\'"};
+    private static final int[] VALUES = {0, 10, 9, 13, 92, 34, 39};
+
+    @Test public void testStringEscapes() {
+        for (int i = 0; i < ESCAPES.length; i++)
+            assertString(ESCAPES[i], new byte[]{(byte)VALUES[i]});
+        assertString("a\\\"b\\\\c\\0d", new byte[]{97, 34, 98, 92, 99, 0, 100});
+        assertString("", new byte[]{});
+        assertString("plain", new byte[]{112, 108, 97, 105, 110});
+    }
+
+    private static void assertString(String text, byte[] expected) {
+        var code = new CodeGen("return \"" + text + "\";").parse().opto().typeCheck();
+        TypeMemPtr ptr = (TypeMemPtr)code.expr()._type;
+        TypeConAryB bytes = (TypeConAryB)ptr._obj._con;
+        assertArrayEquals(text, expected, bytes._ary);
+    }
+
+    @Test public void testCharacterEscapes() {
+        for (int i = 0; i < ESCAPES.length; i++)
+            assertCharacter(ESCAPES[i], VALUES[i]);
+        assertCharacter("A", 65);
+    }
+
+    private static void assertCharacter(String text, int expected) {
+        var code = new CodeGen("return '" + text + "';").parse().opto().typeCheck();
+        assertEquals(text, expected, ((TypeInteger)code.expr()._type).value());
+    }
+
+    @Test public void testMalformedStrings() {
+        assertBadLiteral("return \"\\q\";", "Unknown string escape");
+        assertBadLiteral("return \"abc", "Unclosed string");
+        assertBadLiteral("return \"abc\\", "Unclosed string");
+        // The quote closes the string at EOF; the missing token is the semicolon.
+        assertBadLiteral("return \"plain\"", ";");
+    }
+
+    @Test public void testMalformedCharacters() {
+        assertBadLiteral("return '\\q';", "Unknown character escape");
+        assertBadLiteral("return '", "Unclosed character");
+        assertBadLiteral("return '\\", "Unclosed character");
+        assertBadLiteral("return '';", "Syntax error");
+        assertBadLiteral("return 'ab';", "Syntax error");
+        assertBadLiteral("return 'a", "Syntax error");
+    }
+
+    private static void assertBadLiteral(String src, String message) {
+        try {
+            new CodeGen(src).parse();
+            fail("Accepted malformed literal: " + src);
+        } catch (Parser.ParseException e) {
+            assertTrue(e.getMessage(), e.getMessage().contains(message));
+        }
+    }
+}
diff --git a/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java b/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
index 1ce2cd34..4bd36256 100644
--- a/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
+++ b/src/test/java/com/seaofnodes/simple/MemoryEncodingTest.java
@@ -9,6 +9,7 @@ import com.seaofnodes.simple.codegen.RegAllocTestSupport;
 import com.seaofnodes.simple.node.*;
 import com.seaofnodes.simple.node.cpus.arm.arm;
 import com.seaofnodes.simple.node.cpus.riscv.riscv;
+import com.seaofnodes.simple.type.TypeMemPtr;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -152,8 +153,9 @@ public class MemoryEncodingTest {
             assertNotNull(code._stop.walk(n -> {
                 if( n instanceof MemMergeNode mem &&
                     mem.in(0) instanceof CProjNode exit && exit.in(0) instanceof NeverNode ) {
-                    assertTrue(mem.alias(2) instanceof MemPhiNode);
-                    assertTrue(mem.alias(3) instanceof MemPhiNode);
+                    var fields = ((TypeMemPtr)Parser.TYPES.get("S"))._obj._fields;
+                    assertTrue(mem.alias(fields[0]._alias) instanceof MemPhiNode);
+                    assertTrue(mem.alias(fields[1]._alias) instanceof MemPhiNode);
                     return mem;
                 }
                 return null;
@@ -173,7 +175,7 @@ public class MemoryEncodingTest {
                 c.append("if(memory(").append(arg).append(")!=").append(expected(p,arg)).append("LL) return ").append(arg+1).append(";\n");
             c.append("return 0;\n}\n");
             Files.writeString(Path.of(file+".c"),c);
-            TestC._run("val memory = { int arg -> "+SOURCES[p]+" };",
+            TestC.run("val memory = { int arg -> "+SOURCES[p]+" };",
                 TestC.CALL_CONVENTION,"",file+".c",file,"S","",-1);
         }
     }
diff --git a/src/test/java/com/seaofnodes/simple/Simple.java b/src/test/java/com/seaofnodes/simple/Simple.java
index 705b086a..cd795fae 100644
--- a/src/test/java/com/seaofnodes/simple/Simple.java
+++ b/src/test/java/com/seaofnodes/simple/Simple.java
@@ -17,7 +17,7 @@ public class Simple {
     static final int DUMP_AFTER_OPTO         = 1<<1;
     static final int DUMP_AFTER_TYPE_CHECK   = 1<<2;
     static final int DUMP_AFTER_LOOP_TREE    = 1<<3;
-    static final int DUMP_AFTER_INSTR_SELECT = 1<<4;
+    static final int DUMP_AFTER_SELECT       = 1<<4;
     static final int DUMP_AFTER_GCM          = 1<<5;
     static final int DUMP_AFTER_LOCAL_SCHED  = 1<<6;
     static final int DUMP_AFTER_REG_ALLOC    = 1<<7;
@@ -30,32 +30,29 @@ public class Simple {
 
     static final int DUMP_DISASSEMBLE        = 1<<31;
 
-    static String system_cpu = null;
-    static String system_abi = null;
-
     static void usage() {
         System.out.println(
 """
-simple <input-file> [options] [--eval|--run ...]
+simple [options] <input-file> ...args...
 Options:
-  --dump                     - dump final intermediate representation
-  --dump-after-parse         - dump intermediate representation after parse
-  --dump-after-opto          - dump intermediate representation after opto pass
-  --dump-after-type-check    - dump intermediate representation after type check pass
-  --dump-after-instr-select  - dump intermediate representation after instrution selection pass
-  --dump-after-gcm           - dump intermediate representation after GCM pass
-  --dump-after-local-sched   - dump intermediate representation after local scheduling pass
-  --dump-after-reg-alloc     - dump intermediate representation after register allocation pass
-  --dump-after-encode        - dump intermediate representation after encoding pass
-  --dump-after-all           - dump intermediate representation after all passes
-  -S                         - dump generated assembler code
-  --eval ...                 - evaluate the compiled code in emulator
-  --run ...                  - run the compiled code natively
-  --dump-size                - print the size of generated code
-  --dump-time                - print compilation and execution times
-  --cpu <cpu-name>           - use specific CPU (x86_64_v2, riscv, arm)
-  --abi <abi-name>           - use speific ABI variant (SystemV)
-  --target                   - print native CPU and ABI
+  --dump                   - dump final intermediate representation
+  --dump-after-parse       - dump intermediate representation after parse
+  --dump-after-opto        - dump intermediate representation after opto pass
+  --dump-after-type-check  - dump intermediate representation after type check pass
+  --dump-after-select      - dump intermediate representation after instrution selection pass
+  --dump-after-gcm         - dump intermediate representation after GCM pass
+  --dump-after-local-sched - dump intermediate representation after local scheduling pass
+  --dump-after-reg-alloc   - dump intermediate representation after register allocation pass
+  --dump-after-encode      - dump intermediate representation after encoding pass
+  --dump-after-all         - dump intermediate representation after all passes
+  -S                       - dump generated assembler code
+  --eval                   - evaluate the compiled code in emulator
+  --run                    - run the compiled code natively; this is the default
+  --dump-size              - print the size of generated code
+  --dump-time              - print compilation and execution times
+  --cpu <cpu-name>         - use specific CPU (x86_64_v2, riscv, arm)
+  --abi <abi-name>         - use speific ABI variant (SystemV)
+  --target                 - print native CPU and ABI
   --version
   --help
 """
@@ -63,20 +60,17 @@ Options:
         System.exit(0);
     }
 
-    static void bad_usage() {
-        System.err.println("ERROR: Invalid usage (use --help)");
+    static void bad_usage() { bad("Invalid usage (use --help)"); }
+    static RuntimeException bad(String err) {
+        System.err.println("ERROR: "+err);
         System.exit(1);
+        return new RuntimeException(err);
     }
 
     static void target() {
-        if (system_cpu == null || system_abi == null) {
-            System.err.println("ERROR: Unknown target");
-            System.exit(1);
-        }
-        System.out.print(system_cpu);
+        System.out.print(TestC.CPU_PORT);
         System.out.print("-");
-        System.out.println(system_abi);
-        System.exit(0);
+        System.out.println(TestC.CALL_CONVENTION);
     }
 
     static void dump(CodeGen code, int dump, int pass) {
@@ -87,11 +81,11 @@ Options:
                     case DUMP_AFTER_OPTO         -> "After OPTO:";
                     case DUMP_AFTER_TYPE_CHECK   -> "After Type Check:";
                     case DUMP_AFTER_LOOP_TREE    -> "After Loop Tree:";
-                    case DUMP_AFTER_INSTR_SELECT -> "After Instruction Selection:";
+                    case DUMP_AFTER_SELECT       -> "After Code Selection:";
                     case DUMP_AFTER_GCM          -> "After GCM:";
                     case DUMP_AFTER_LOCAL_SCHED  -> "After Local Scheduling:";
                     case DUMP_AFTER_REG_ALLOC    -> "After Register Allocation:";
-                    case DUMP_AFTER_ENCODE       -> "After Instruction Encoding:";
+                    case DUMP_AFTER_ENCODE       -> "After Encoding:";
                     case DUMP_FINAL              -> "Final:";
                     default                      -> throw Utils.TODO();
                 });
@@ -106,24 +100,24 @@ Options:
         double t, total = 0;
 
         total += t = code._tParse / 1e3;
-        System.out.println(String.format("Parsing Time:               %.3f sec", t));
+        System.out.printf( "Parsing Time:             %.3f sec%n", t);
         total += t = code._tOpto / 1e3;
-        System.out.println(String.format("Optimization Time:          %.3f sec", t));
+        System.out.printf( "Optimization Time:        %.3f sec%n", t);
         total += t = code._tTypeCheck / 1e3;
-        System.out.println(String.format("Type Checking Time:         %.3f sec", t));
+        System.out.printf( "Type Checking Time:       %.3f sec%n", t);
         total += t = code._tLoopTree / 1e3;
-        System.out.println(String.format("Loop Tree Time:             %.3f sec", t));
+        System.out.printf( "Loop Tree Time:           %.3f sec%n", t);
         total += t = code._tInsSel / 1e3;
-        System.out.println(String.format("Instruction Selection Time: %.3f sec", t));
+        System.out.printf( "Code Selection Time:      %.3f sec%n", t);
         total += t = code._tGCM / 1e3;
-        System.out.println(String.format("GCM Time:                   %.3f sec", t));
+        System.out.printf( "GCM Time:                 %.3f sec%n", t);
         total += t = code._tLocal / 1e3;
-        System.out.println(String.format("Local Scheduling Time:      %.3f sec", t));
+        System.out.printf( "Local Scheduling Time:    %.3f sec%n", t);
         total += t = code._tRegAlloc / 1e3;
-        System.out.println(String.format("Register Allocation Time:   %.3f sec", t));
+        System.out.printf( "Register Allocation Time: %.3f sec%n", t);
         total += t = code._tEncode / 1e3;
-        System.out.println(String.format("Instruction Encoding Time:  %.3f sec", t));
-        System.out.println(String.format("TOTAL COMPILATION TIME:     %.3f sec", total));
+        System.out.printf( "Encoding Time:            %.3f sec%n", t);
+        System.out.printf( "TOTAL COMPILATION TIME:   %.3f sec%n", total);
     }
 
     static String getInput() throws IOException {
@@ -134,9 +128,8 @@ Options:
 
     public static void main(String[] args) throws Exception {
         String input_filename = null;
-        boolean use_stdin = false;
         boolean do_eval = false;
-        boolean do_run = false;
+        boolean do_run = true;
         boolean do_codegen = false;
         boolean do_print_size = false;
         boolean do_print_time = false;
@@ -146,77 +139,61 @@ Options:
         String cpu = null;
         String abi = null;
 
-        // TODO: autodetect
-        system_cpu = "x86_64_v2";
-        system_abi = "SystemV";
-
         // Parse command line
-loop:   for (int i = 0; i < args.length; i++) {
+        int i; for( i = 0; i < args.length; i++ ) {
             String arg = args[i];
-            if (arg.charAt(0) == '-') {
-                switch (arg) {
-                    case "-":                         use_stdin = true; break;
-                    case "--dump":                    dump |= DUMP_FINAL; break;
-                    case "--dump-after-parse":        dump |= DUMP_AFTER_PARSE; break;
-                    case "--dump-after-opto":         dump |= DUMP_AFTER_OPTO; break;
-                    case "--dump-after-type-check":   dump |= DUMP_AFTER_TYPE_CHECK; break;
-                    case "--dump-after-loop-tree":    dump |= DUMP_AFTER_LOOP_TREE; break;
-                    case "--dump-after-instr-select": dump |= DUMP_AFTER_INSTR_SELECT; break;
-                    case "--dump-after-gcm":          dump |= DUMP_AFTER_GCM; break;
-                    case "--dump-after-local-sched":  dump |= DUMP_AFTER_LOCAL_SCHED; break;
-                    case "--dump-after-reg-alloc":    dump |= DUMP_AFTER_REG_ALLOC; break;
-                    case "--dump-after-encode":       dump |= DUMP_AFTER_ENCODE; break;
-                    case "--dump-after-all":          dump |= DUMP_AFTER_ALL; break;
-                    case "-S":                        dump |= DUMP_DISASSEMBLE; break;
-                    case "--eval":                    do_eval = true; first_arg = i + 1; break loop;
-                    case "--run":                     do_run = true; first_arg = i + 1; break loop;
-                    case "--dump-size":               do_print_size = true; break;
-                    case "--dump-time":               do_print_time = true; break;
-                    case "--cpu":                     if (cpu != null
-                                                       || i + 1 >= args.length
-                                                       || args[i + 1].charAt(0) == '-') bad_usage();
-                                                      cpu = args[i + 1];
-                                                      i++;
-                                                      break;
-                    case "--abi":                     if (abi != null
-                                                       || i + 1 >= args.length
-                                                       || args[i + 1].charAt(0) == '-') bad_usage();
-                                                      abi = args[i + 1];
-                                                      i++;
-                                                      break;
-                    case "--target":                  target();
-                    case "--version":                 throw Utils.TODO();
-                    case "--help":                    usage();
-                    default:                          bad_usage();
-                }
-            } else {
-                if (input_filename != null || use_stdin) bad_usage();
+            if( arg.charAt(0) != '-' ) {
                 input_filename = arg;
+                break;
             }
-        }
 
-        if (input_filename == null && !use_stdin) {
-            System.err.println("ERROR: no input file' (use --help)");
-            System.exit(1);
+            switch (arg) {
+            case "-":                         input_filename=""; break;
+            case "--dump":                    dump |= DUMP_FINAL; break;
+            case "--dump-after-parse":        dump |= DUMP_AFTER_PARSE; break;
+            case "--dump-after-opto":         dump |= DUMP_AFTER_OPTO; break;
+            case "--dump-after-type-check":   dump |= DUMP_AFTER_TYPE_CHECK; break;
+            case "--dump-after-loop-tree":    dump |= DUMP_AFTER_LOOP_TREE; break;
+            case "--dump-after-select":       dump |= DUMP_AFTER_SELECT; break;
+            case "--dump-after-gcm":          dump |= DUMP_AFTER_GCM; break;
+            case "--dump-after-local-sched":  dump |= DUMP_AFTER_LOCAL_SCHED; break;
+            case "--dump-after-reg-alloc":    dump |= DUMP_AFTER_REG_ALLOC; break;
+            case "--dump-after-encode":       dump |= DUMP_AFTER_ENCODE; break;
+            case "--dump-after-all":          dump |= DUMP_AFTER_ALL; break;
+            case "-S":                        dump |= DUMP_DISASSEMBLE; break;
+            case "--eval":                    do_eval = true ; do_run = false; break;
+            case "--run":                     do_run  = true ; break;
+            case "--norun":                   do_run  = false; break;
+            case "--dump-size":               do_print_size = true; break;
+            case "--dump-time":               do_print_time = true; break;
+            case "--cpu":                     if (cpu != null || i + 1 >= args.length || args[i + 1].charAt(0) == '-') bad_usage();
+                                              cpu = args[++i];
+                                              break;
+            case "--abi":                     if (abi != null || i + 1 >= args.length || args[i + 1].charAt(0) == '-') bad_usage();
+                                              abi = args[++i];
+                                              break;
+            case "--target":                  target(); break;
+            case "--version":                 throw Utils.TODO();
+            case "--help":                    usage();
+            default:                          bad_usage();
+            }
         }
 
+        if (input_filename == null) throw bad("no input file' (use --help)");
+        if( !input_filename.isEmpty() && !input_filename.endsWith(".smp") )
+            throw bad("File extension must be .smp");
+        String base = input_filename.substring(0,input_filename.length()-4);
+
         if (do_run || (dump & DUMP_DISASSEMBLE) != 0 || do_print_size) {
-            if (cpu == null) cpu = system_cpu;
-            if (abi == null) abi = system_abi;
-            if (cpu == null || abi == null) {
-                System.err.println("ERROR: Cannot compile for unknown target");
-                System.exit(1);
-            }
+            if (cpu == null) cpu = TestC.CPU_PORT;
+            if (abi == null) abi = TestC.CALL_CONVENTION;
             do_codegen = true;
         }
 
         // Read input file
         try {
-            src = use_stdin ? getInput() : Files.readString(Path.of(input_filename));
-        } catch(IOException e) {
-            System.err.println("ERROR: Cannot read input file");
-            System.exit(1);
-        }
+            src = input_filename.isEmpty() ? getInput() : Files.readString(Path.of(input_filename));
+        } catch( IOException e ) { throw bad("Cannot read input file: "+input_filename);  }
 
         // Compilation pipeline
         CodeGen code = new CodeGen(src);
@@ -234,8 +211,8 @@ loop:   for (int i = 0; i < args.length; i++) {
         dump(code, dump, DUMP_AFTER_LOOP_TREE);
 
         if (do_codegen) {
-            code.instSelect(PORTS, cpu, abi);
-            dump(code, dump, DUMP_AFTER_INSTR_SELECT);
+            code.instSelect(cpu, abi, PORTS);
+            dump(code, dump, DUMP_AFTER_SELECT);
         }
 
         code.GCM();
@@ -250,6 +227,8 @@ loop:   for (int i = 0; i < args.length; i++) {
 
             code.encode();
             dump(code, dump, DUMP_AFTER_ENCODE);
+
+            code.exportELF(base+".o");
         }
 
         dump(code, dump, DUMP_FINAL);
@@ -259,7 +238,7 @@ loop:   for (int i = 0; i < args.length; i++) {
         }
 
         if (do_print_size) {
-             System.out.println(String.format("Code Size: %d", code._encoding._bits.size()));
+             System.out.printf( "Code Size: %d%n", code._encoding._bits.size());
         }
 
         if (do_print_time) {
@@ -269,19 +248,19 @@ loop:   for (int i = 0; i < args.length; i++) {
         if (do_eval) {
             // TODO: Support for evaluation of functions with different argument numbers and types
             long t = System.currentTimeMillis();
-            long arg = (first_arg < args.length) ? Integer.valueOf(args[first_arg]) : 0;
+            long arg = (i+1 < args.length) ? Integer.parseInt(args[i+1]) : 0;
             System.out.println(Eval2.eval(code, arg, 100000));
             if (do_print_time) {
-                System.out.println(String.format("EXECUTION TIME:             %.3f sec",
-                    (System.currentTimeMillis() - t) / 1e3));
+                System.out.printf( "EXECUTION TIME:             %.3f sec%n",
+                    (System.currentTimeMillis() - t) / 1e3);
             }
-        } else if (do_run) {
-            if (cpu != system_cpu || abi != system_abi) {
-                System.err.println("ERROR: cannot run code on not native target");
-                System.exit(1);
-            }
-
-            throw Utils.TODO();
+        }
+        if (do_run) {
+            if ( !TestC.CPU_PORT.equals( cpu ) || !TestC.CALL_CONVENTION.equals( abi ) )
+                throw bad("cannot run code on not native target");
+            String exe = TestC.OS.startsWith("Windows") ? base+".exe" : base;
+            String result = com.seaofnodes.simple.TestC.gcc(base+".o", null, null, true, exe);
+            System.out.print(result);
         }
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/SpillStats.java b/src/test/java/com/seaofnodes/simple/SpillStats.java
index 318a6e33..82cffef8 100644
--- a/src/test/java/com/seaofnodes/simple/SpillStats.java
+++ b/src/test/java/com/seaofnodes/simple/SpillStats.java
@@ -26,6 +26,13 @@ public class SpillStats extends RunListener {
                            code._regAlloc._spills+","+code._regAlloc._spillScaled);
     }
 
+    // The same native helpers serve old and new program cohorts.
+    public static void recordNative(CodeGen code, String cpu, String abi) {
+        String cohort = ACTIVE!=null && ACTIVE._test.getTestClass()==Chapter22Test.class
+            ? "Chapter22" : "Chapter21";
+        record(code,cohort,cpu,abi);
+    }
+
     // Keep running every CPU and native result check when measuring quality.
     // A changed golden still makes spill-stats fail at the end.
     public static void checkSpills(int expected, int actual) {
@@ -39,7 +46,7 @@ public class SpillStats extends RunListener {
     }
 
     public static void main(String[] args) throws ClassNotFoundException {
-        if( args.length==0 ) args = new String[]{"Chapter20Test","Chapter21Test","Chapter21AllocTest","BrainFuckTest","MergeSortTest"};
+        if( args.length==0 ) args = new String[]{"Chapter20Test","Chapter21Test","Chapter21AllocTest","Chapter22Test","BrainFuckTest","MergeSortTest"};
         Class<?>[] tests = new Class<?>[args.length];
         for( int i=0; i<args.length; i++ )
             tests[i] = Class.forName("com.seaofnodes.simple."+args[i]);
@@ -48,7 +55,8 @@ public class SpillStats extends RunListener {
         junit.addListener(ACTIVE);
         Result result = junit.run(tests);
         boolean passed = result.wasSuccessful() && ACTIVE._qualityFailures==0;
-        if( !passed ) System.out.println("FAILED test run: totals are not a complete comparison.");
+        if( !result.wasSuccessful() ) System.out.println("FAILED test run: totals are not a complete comparison.");
+        else if( !passed ) System.out.println("Spill expectations differ; allocation and runtime checks passed.");
         System.out.println("cohort,cpu,abi,allocations,splits,scaled");
         for( var row : ACTIVE._totals.entrySet() ) {
             long[] sum = row.getValue();
diff --git a/src/test/java/com/seaofnodes/simple/TestArm64.java b/src/test/java/com/seaofnodes/simple/TestArm64.java
index e4bc38a0..a22063eb 100644
--- a/src/test/java/com/seaofnodes/simple/TestArm64.java
+++ b/src/test/java/com/seaofnodes/simple/TestArm64.java
@@ -2,6 +2,8 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.isa.eval.EvalArm64;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
+
 
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.cpus.arm.arm;
@@ -23,9 +25,8 @@ public class TestArm64 {
     public static EvalArm64 build( String dir, String file, int arg, int spills, boolean print ) throws IOException {
         // Compile and export Simple
         String src = Files.readString(Path.of(dir+"/"+file+".smp"));
-        CodeGen code = new CodeGen(src).driver("arm", "SystemV",null);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
-        SpillStats.record(code,"Chapter21","arm","SystemV");
+        CodeGen code = new CheckedCodeGen(src).driver("arm", "SystemV",null);
+        SpillStats.recordNative(code,"arm","SystemV");
         if( print ) { code.print_as_hex(); System.out.print(code.asm()); }
 
         // Allocation quality not degraded
diff --git a/src/test/java/com/seaofnodes/simple/TestC.java b/src/test/java/com/seaofnodes/simple/TestC.java
index b3e21ea7..44c06128 100644
--- a/src/test/java/com/seaofnodes/simple/TestC.java
+++ b/src/test/java/com/seaofnodes/simple/TestC.java
@@ -1,10 +1,11 @@
 package com.seaofnodes.simple;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 import com.seaofnodes.simple.codegen.CodeGen;
+import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.io.InputStream;
-import java.io.IOException;
+import java.util.concurrent.TimeUnit;
 import static org.junit.Assert.*;
 
 // Call a C driver program, which calls a Simple-generated .o, and self-checks.
@@ -16,8 +17,8 @@ public abstract class TestC {
 
     public static final String CALL_CONVENTION = OS.startsWith("Windows") ? "Win64" : "SystemV";
     public static final String CPU_PORT = switch( CPU ) {
-    case "amd64" -> "x86_64_v2";
-    default -> throw Utils.TODO("Map Yer CPU Port Here");
+        case "amd64" -> "x86_64_v2";
+        default -> throw Utils.TODO("Map Yer CPU Port Here");
     };
 
     public static void run( String file, int spills ) throws IOException { run(file,"",spills); }
@@ -35,54 +36,69 @@ public abstract class TestC {
 
         // Compile and export Simple
         String src = Files.readString(Path.of(sfile));
-        _run(src,CALL_CONVENTION,"",cfile,efile,"S",expected,spills);
+        run(src,CALL_CONVENTION,"",cfile,efile,"S",expected,spills);
     }
 
-    static void _run( String src, String simple_conv, String c_conv, String cfile, String efile, String xtn, String expected, int spills ) throws IOException {
+    public static void run( String src, String simple_conv, String c_conv, String cfile, String efile, String xtn, String expected, int spills ) throws IOException {
         String bin = efile+xtn;
         String obj = bin+".o";
+        String exe = OS.startsWith("Windows") ? bin+".exe" : bin;
         // Compile simple, emit ELF
-        CodeGen code = new CodeGen(src).driver( CPU_PORT, simple_conv, obj);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
-        SpillStats.record(code,"Chapter21",CPU_PORT,simple_conv);
+        CodeGen code = new CheckedCodeGen(src).driver( CPU_PORT, simple_conv, obj);
+        SpillStats.recordNative(code,CPU_PORT,simple_conv);
+        String result = gcc(obj, c_conv, cfile, false, exe );
+        assertEquals(expected,result);
+
+        // Allocation quality not degraded
+        SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
+    }
+
+    public static String gcc( String obj, String c_conv, String cfile, boolean stdin, String... args ) throws IOException {
+
+        // Compile the C program.  Compiling code and constants in the low
+        // 2Gig.  Pointers are 64b BUT since always in the low 2G all the
+        // high bits are zero - and Simple code can be emitted treating
+        // pointers as 4bytes.
+        var params = new Ary<>(String.class);
+        params.add("gcc");
+        if( cfile!=null ) params.add(cfile); // Associated C driver, usually has a `main`
+        params.addAll(new String[] {
+                obj,
+                "-lm", // Picks up 'sqrt' for newtonFloat tests to compare
+                "-g",
+                "-o",
+                args[0],
+        });
+        // Calling convention for C calls, if any
+        if( cfile!=null ) {
+            params.add("-D");
+            params.add("CALL_CONV="+c_conv);
+        }
 
-        // Compile the C program
-        var params = new String[] {
-            //if (USE_WSL) "wsl.exe";
-            "gcc",
-            cfile,
-            obj,
-            "-lm", // Picks up 'sqrt' for newtonFloat tests to compare
-            "-g",
-            "-o",
-            bin,
-            "-D",
-            "CALL_CONV="+c_conv,
-        };
-        Process gcc = new ProcessBuilder(params).redirectErrorStream(true).start();
-        int error;
-        try { error = gcc.waitFor(); } catch( InterruptedException e ) { throw new IOException("interrupted"); }
+        // Run GCC to link (optionally compile C driver code)
+        Process gcc = new ProcessBuilder(params.asAry()).redirectErrorStream(true).start();
+        int exit;
+        try {
+            boolean normal = gcc.waitFor(2, TimeUnit.SECONDS);
+            exit = normal ? gcc.exitValue() : -1; // no exit???
+        }  catch( InterruptedException e ) {
+            throw new IOException("interrupted");
+        }
         String result = new String(gcc.getInputStream().readAllBytes());
-        if( error!=0 ) {
-            System.err.println("gcc error code: "+error);
+        if( exit!=0 ) {
+            System.err.println("gcc error code: "+exit);
             System.err.println(result);
         }
-        assertEquals( 0, error );
+        assertEquals( 0, exit );
         //assertTrue(result.isEmpty()); // No data in error stream
 
         // Execute results
-        Process smp = new ProcessBuilder(bin).redirectErrorStream(true).start();
-        try { error = smp.waitFor(); } catch( InterruptedException e ) { throw new IOException("interrupted"); }
-        result = new String(smp.getInputStream().readAllBytes());
-        if( error!=0 ) {
-            System.err.println("exec error code: "+error);
-            System.err.println(result);
-        }
-        assertEquals( 0, error );
-        assertEquals(expected,result);
-
-        // Allocation quality not degraded
-        SpillStats.checkSpills(spills,code._regAlloc._spillScaled);
-
+        ProcessBuilder smp = new ProcessBuilder(args);
+        if( stdin ) smp.redirectInput(ProcessBuilder.Redirect.INHERIT);
+        Process p = smp.start();
+        try { exit = p.waitFor(); } catch( InterruptedException e ) { throw new IOException("interrupted"); }
+        result = new String(p.getInputStream().readAllBytes());
+        assertEquals("Program exit status",0,exit);
+        return result;
     }
 }
diff --git a/src/test/java/com/seaofnodes/simple/TestRisc5.java b/src/test/java/com/seaofnodes/simple/TestRisc5.java
index 1289575d..ace2a7ea 100644
--- a/src/test/java/com/seaofnodes/simple/TestRisc5.java
+++ b/src/test/java/com/seaofnodes/simple/TestRisc5.java
@@ -2,6 +2,7 @@ package com.seaofnodes.simple;
 
 import com.seaofnodes.isa.eval.EvalRisc5;
 
+import com.seaofnodes.simple.codegen.RegAllocTestSupport.CheckedCodeGen;
 import com.seaofnodes.simple.codegen.CodeGen;
 import com.seaofnodes.simple.node.FunNode;
 import com.seaofnodes.simple.node.Node;
@@ -22,9 +23,8 @@ public abstract class TestRisc5 {
     public static EvalRisc5 build( String dir, String file, String main, int arg, int spills, boolean print ) throws IOException {
         // Compile and export Simple
         String src = Files.readString(Path.of(dir+"/"+file+".smp"));
-        CodeGen code = new CodeGen(src).driver("riscv", "SystemV",null);
-        com.seaofnodes.simple.codegen.RegAllocTestSupport.checkRegisters(code);
-        SpillStats.record(code,"Chapter21","riscv","SystemV");
+        CodeGen code = new CheckedCodeGen(src).driver("riscv", "SystemV",null);
+        SpillStats.recordNative(code,"riscv","SystemV");
         if( print ) { code.print_as_hex(); System.out.print(code.asm()); }
 
         // Allocation quality not degraded
diff --git a/src/test/java/com/seaofnodes/simple/TypeTest.java b/src/test/java/com/seaofnodes/simple/TypeTest.java
index dee033bc..551bddad 100644
--- a/src/test/java/com/seaofnodes/simple/TypeTest.java
+++ b/src/test/java/com/seaofnodes/simple/TypeTest.java
@@ -20,9 +20,9 @@ public class TypeTest {
         TypeStruct s2 = TypeStruct.make("s2", new Field[]{
                 Field.make("a", TypeInteger.BOT,-3, false),
                 Field.make("b", TypeInteger.BOT,-4, false) });
-        Assert.assertEquals(s1.makeRO(), s1.glb());
+        Assert.assertEquals(s1.makeRO(), s1.glb(false));
         Assert.assertNotEquals(s1, s1.dual());
-        Assert.assertEquals(s1.makeRO(), s1.dual().glb());
+        Assert.assertEquals(s1.makeRO(), s1.dual().glb(false));
 
         TypeMem m1 = TypeMem.make(1,TypeNil.NIL);
         TypeMem m2 = TypeMem.make(2,TypeInteger.U16);
@@ -38,9 +38,9 @@ public class TypeTest {
         Assert.assertEquals(TypeMem.make(0,Type.BOTTOM), m1.meet(m3));
         Assert.assertEquals(TypeMem   .BOT, m3.meet(m4));
 
-        Assert.assertEquals(TypeMem.make(1,Type.BOTTOM), m1.glb());
+        Assert.assertEquals(TypeMem.make(1,Type.BOTTOM), m1.glb(false));
         Assert.assertEquals(TypeMem.make(1,Type.XNIL), m1.dual());
-        Assert.assertEquals(m4.dual(), m4.glb().dual());
+        Assert.assertEquals(m4.dual(), m4.glb(false).dual());
 
         TypeMemPtr ptr1 = TypeMemPtr.make(s1);
         Assert.assertEquals(s1, ptr1._obj);
@@ -55,11 +55,11 @@ public class TypeTest {
         Assert.assertEquals(s2, ptr2nil._obj);
 
         Assert.assertNotEquals(ptr1, ptr2);
-        Assert.assertNotEquals(ptr1, ptr1.glb());
-        Assert.assertEquals(ptr1nil.makeFrom(s1.glb()).makeRO(), ptr1.glb());
+        Assert.assertNotEquals(ptr1, ptr1.glb(false));
+        Assert.assertEquals(ptr1nil.makeFrom(s1.glb(false)).makeRO(), ptr1.glb(false));
 
         Assert.assertEquals(ptr1, ptr1.dual().dual());
-        Assert.assertEquals(ptr1.glb().makeFrom(s1.dual().glb()), ptr1.dual().glb());
+        Assert.assertEquals(ptr1.glb(false).makeFrom(s1.dual().glb(false)), ptr1.dual().glb(false));
         Assert.assertEquals(TypeMemPtr.makeNullable(TypeStruct.BOT).withAccess(false), ptr1.meet(ptr2nil));
         Assert.assertEquals(ptr1nil, ptr1.meet(TypeNil.NIL));
 
diff --git a/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java b/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
index 739eba3b..2d9860a6 100644
--- a/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
+++ b/src/test/java/com/seaofnodes/simple/codegen/RegAllocTestSupport.java
@@ -118,6 +118,16 @@ public class RegAllocTestSupport {
         assertTrue(BuildLRG.run(0,new RegAlloc(code)));
     }
 
+    // Check the scheduled graph before encoding adds untyped branches or rewrites tail calls.
+    public static class CheckedCodeGen extends CodeGen {
+        public CheckedCodeGen(String src) { super(src); }
+        @Override public CodeGen regAlloc() {
+            super.regAlloc();
+            checkRegisters(this);
+            return this;
+        }
+    }
+
     public static void topPhi() {
         // Either arm can be the synthetic exit.  Both predecessors share a
         // block here so making TOP live would conflict with the real value.
diff --git a/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java b/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
index 368c243b..0914d916 100644
--- a/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
+++ b/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
@@ -3,6 +3,7 @@ package com.seaofnodes.simple.codegen;
 import com.seaofnodes.simple.node.Node;
 import com.seaofnodes.simple.node.cpus.x86_64_v2.CmpMemX86;
 import com.seaofnodes.simple.node.cpus.x86_64_v2.NotX86;
+import com.seaofnodes.simple.node.cpus.x86_64_v2.MulIX86;
 import org.junit.Test;
 import static org.junit.Assert.*;
 
@@ -11,7 +12,7 @@ public class X86EncodingTest {
     @Test
     public void testLogicalNotRegisters() {
         CodeGen code = new CodeGen("return !arg;")
-            .driver(CodeGen.Phase.InstSelect, "x86_64_v2", "SystemV");
+            .driver(CodeGen.Phase.Select, "x86_64_v2", "SystemV");
         var not = code._stop.walk(n -> n instanceof NotX86 ? (NotX86)n : null);
         assertNotNull("Must exercise logical not", not);
         int[][] registers = {{0,0}, {1,1}, {7,7}, {9,9}, {1,9}, {9,1}, {6,0}, {15,8}};
@@ -50,6 +51,31 @@ public class X86EncodingTest {
             """);
         com.seaofnodes.simple.TestC.run("build/objs", "x86LogicalNot", "", -1);
     }
+
+    @Test
+    public void testMultiplyImmediateRegisters() {
+        // Destination, source, expected REX and ModRM. Cross the register-8
+        // boundary in both directions, with low/low and high/high controls.
+        int[][] cases = {{1, 9, 0x49, 0xC9}, {9, 1, 0x4C, 0xC9},
+                         {1, 2, 0x48, 0xCA}, {9, 10, 0x4D, 0xCA}};
+        for (int immediate : new int[]{11, -11, 123456789, -123456789}) {
+            CodeGen code = new CodeGen("return arg * " + immediate + ";")
+                .driver(CodeGen.Phase.Select, "x86_64_v2", "SystemV");
+            var mul = code._stop.walk(n -> n instanceof MulIX86 ? n : null);
+            assertNotNull("Must exercise immediate multiply", mul);
+            for (int[] regs : cases) {
+                var enc = new FixedRegisterEncoding(
+                    code, mul, regs[0], mul.in(1), regs[1]);
+                ((MulIX86)mul).encoding(enc);
+                boolean small = immediate == 11 || immediate == -11;
+                assertEquals("REX for dst=" + regs[0] + ", src=" + regs[1], regs[2], enc.read1(0));
+                assertEquals(small ? 0x6B : 0x69, enc.read1(1));
+                assertEquals(regs[3], enc.read1(2));
+                assertEquals(small ? 4 : 7, enc._bits.size());
+                assertEquals(immediate, small ? (byte)enc.read1(3) : enc.read4(3));
+            }
+        }
+    }
     @Test
     public void testMemoryCompare64Immediate32() {
         for (int immediate : new int[]{123456789, -123456789}) {
diff --git a/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java b/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
index 167a5b24..79547c0d 100644
--- a/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
+++ b/src/test/java/com/seaofnodes/simple/fuzzer/ScriptGenerator.java
@@ -97,7 +97,7 @@ public class ScriptGenerator {
     private static final List<TypeInt> INTTYPES = new ArrayList<>();
 
     static {
-        for( var e : Parser.defaultTypes().entrySet() ) {
+        for( var e : Parser.TYPES.entrySet() ) {
             if( e.getValue() instanceof TypeInteger ) {
                 INTTYPES.add(new TypeInt(e.getKey()));
             }
diff --git a/src/test/java/com/seaofnodes/simple/progs/c_returns.c b/src/test/java/com/seaofnodes/simple/progs/c_returns.c
new file mode 100644
index 00000000..6d0ff2fe
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/c_returns.c
@@ -0,0 +1,28 @@
+#include <stdint.h>
+#include <stdio.h>
+
+uint64_t c_bits;
+// Legal narrow C returns: unused RAX bits deliberately contain garbage.
+#define RET(name) __asm__(".text\n.globl " #name "\n" #name ":\nmovq c_bits(%rip), %rax\nret\n");
+RET(c_i8) RET(c_u8) RET(c_i16) RET(c_u16) RET(c_i32) RET(c_u32) RET(c_i64)
+#define DECL(name) extern int64_t __attribute__((CALL_CONV)) name(void);
+DECL(test_i8) DECL(test_u8) DECL(test_i16) DECL(test_u16)
+DECL(test_i32) DECL(test_u32) DECL(test_i64) DECL(test_cmp)
+
+int main(void) {
+    uint64_t values[] = {0xa5a5a5a500000000ULL, 0xa5a5a5a50000007fULL,
+        0xa5a5a5a500000080ULL, 0xa5a5a5a500007fffULL, 0xa5a5a5a500008000ULL,
+        0xa5a5a5a57fffffffULL, 0xa5a5a5a580000000ULL, 0xa5a5a5a5ffffffffULL};
+    for(unsigned i=0; i<sizeof(values)/sizeof(values[0]); i++) {
+        c_bits=values[i];
+        int64_t actual[]={test_i8(),test_u8(),test_i16(),test_u16(),test_i32(),test_u32(),test_i64(),test_cmp()};
+        int64_t expected[]={(int8_t)c_bits,(uint8_t)c_bits,(int16_t)c_bits,(uint16_t)c_bits,
+                            (int32_t)c_bits,(uint32_t)c_bits,(int64_t)c_bits,(int32_t)c_bits==-1};
+        for(unsigned j=0; j<8; j++)
+            if(actual[j]!=expected[j]) {
+                printf("case %u type %u: %lld != %lld\n",i,j,(long long)actual[j],(long long)expected[j]);
+                return 1;
+            }
+    }
+    return 0;
+}
diff --git a/src/test/java/com/seaofnodes/simple/progs/echo.smp b/src/test/java/com/seaofnodes/simple/progs/echo.smp
new file mode 100644
index 00000000..8eafd73b
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/echo.smp
@@ -0,0 +1,3 @@
+// -*- mode: java;  -*-
+// Echo stdin to stdout.
+return sys.io.p( sys.io.stdin() );
diff --git a/src/test/java/com/seaofnodes/simple/progs/funptr.c b/src/test/java/com/seaofnodes/simple/progs/funptr.c
new file mode 100644
index 00000000..7545992d
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/funptr.c
@@ -0,0 +1,15 @@
+#include <assert.h>
+#include <stdint.h>
+
+typedef int64_t (*Function)(void);
+typedef int64_t (*Printer)(void *);
+extern Function factory(int64_t);
+extern Printer printer(void);
+
+int main(void) {
+    assert(factory(1)() == 42);
+    assert(factory(0)() == 43);
+    struct { uint32_t length; char data[2]; } text = {2, {'o','k'}};
+    printer()(&text);
+    return 0;
+}
diff --git a/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp b/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp
new file mode 100644
index 00000000..07ff935f
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/helloWorld.smp
@@ -0,0 +1,3 @@
+// -*- mode: java;  -*-
+sys.io.p("Hello, World!");
+return 0;
diff --git a/src/test/java/com/seaofnodes/simple/progs/jig.smp b/src/test/java/com/seaofnodes/simple/progs/jig.smp
index 1daeee09..29987d8e 100644
--- a/src/test/java/com/seaofnodes/simple/progs/jig.smp
+++ b/src/test/java/com/seaofnodes/simple/progs/jig.smp
@@ -1,2 +1,16 @@
 // -*- mode: java;  -*-
-return 0;
+val _fib = {int n ->
+    int temp=0;
+    int f1=1;
+    int f2=1;
+    int i=n;
+    while( i>1 ){
+        temp = f1+f2;
+        f1=f2;
+        f2=temp;
+        i=i-1;
+    }
+    return f2;
+};
+
+_fib(10);
diff --git a/src/test/java/com/seaofnodes/simple/progs/person.smp b/src/test/java/com/seaofnodes/simple/progs/person.smp
index b5e6ee90..94e2cdde 100644
--- a/src/test/java/com/seaofnodes/simple/progs/person.smp
+++ b/src/test/java/com/seaofnodes/simple/progs/person.smp
@@ -1,6 +1,6 @@
 // -*-java-*-
 struct Person {
-    int age;
+    i32 age;
 };
 
 val fcn = { !Person?[] ps, int x ->
diff --git a/src/test/java/com/seaofnodes/simple/progs/person21.c b/src/test/java/com/seaofnodes/simple/progs/person21.c
new file mode 100644
index 00000000..df95e1ca
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/person21.c
@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+typedef struct Person {
+    int age;
+} Person;
+
+typedef struct PersonArray {
+    unsigned int length;
+    int pad;
+    Person* data[];
+} PersonArray;
+
+__attribute__ ((CALL_CONV))
+extern void fcn(PersonArray* people, int index);
+
+int main() {
+    Person base[5] = {{25},{1},{18},{45},{60}};
+    unsigned char buf[8+8*5];
+    PersonArray* people_array = (PersonArray*)buf;
+    people_array->length=5;
+    for (int i=0; i<people_array->length; i++) people_array->data[i] = &base[i];
+
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+    fcn(people_array, 1);
+
+    printf("%d\n", people_array->data[1]->age); // expected: 6
+
+    return 0;
+}
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/person21.smp b/src/test/java/com/seaofnodes/simple/progs/person21.smp
new file mode 100644
index 00000000..b5e6ee90
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/person21.smp
@@ -0,0 +1,9 @@
+// -*-java-*-
+struct Person {
+    int age;
+};
+
+val fcn = { !Person?[] ps, int x ->
+    if( ps[x] )
+        ps[x].age++;
+};
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp b/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
new file mode 100644
index 00000000..1a36fb99
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age += arg;
+return p.age;
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp
new file mode 100644
index 00000000..57b37477
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp
@@ -0,0 +1,4 @@
+struct Person {i64 age;}
+!Person !p  = new Person;
+p.age += arg;
+return p.age;
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp
new file mode 100644
index 00000000..7d7fdce7
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp
@@ -0,0 +1,5 @@
+// Should fold away sign extend
+struct Person { i8 age;};
+!Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp
new file mode 100644
index 00000000..4d6ca3a3
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age = (arg<<17)>>17;
+return 0;
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp
new file mode 100644
index 00000000..5c96c060
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+!Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
\ No newline at end of file
diff --git a/src/test/java/com/seaofnodes/simple/progs/store_peep.smp b/src/test/java/com/seaofnodes/simple/progs/store_peep.smp
new file mode 100644
index 00000000..c3feddd5
--- /dev/null
+++ b/src/test/java/com/seaofnodes/simple/progs/store_peep.smp
@@ -0,0 +1,3 @@
+i64 a = 123456789012345;
+i32 b = a; // truncate high order bits
+return b;
\ No newline at end of file