diff options
Diffstat (limited to 'src/main/java/com/seaofnodes/simple/node/ScopeNode.java')
| -rw-r--r-- | src/main/java/com/seaofnodes/simple/node/ScopeNode.java | 471 |
1 files changed, 322 insertions, 149 deletions
diff --git a/src/main/java/com/seaofnodes/simple/node/ScopeNode.java b/src/main/java/com/seaofnodes/simple/node/ScopeNode.java index 307fc0f9..92cad745 100644 --- a/src/main/java/com/seaofnodes/simple/node/ScopeNode.java +++ b/src/main/java/com/seaofnodes/simple/node/ScopeNode.java @@ -5,18 +5,18 @@ import com.seaofnodes.print.ExprPrinter; import com.seaofnodes.simple.Parser; import com.seaofnodes.simple.Var; import com.seaofnodes.simple.codegen.CodeGen; +import com.seaofnodes.simple.codegen.ParseAll; +import com.seaofnodes.simple.codegen.CompUnit; import com.seaofnodes.simple.type.*; import com.seaofnodes.simple.util.Ary; -import com.seaofnodes.simple.util.AryInt; import com.seaofnodes.simple.util.Utils; - import java.util.*; /** * The Scope node is purely a parser helper - it tracks names to nodes with a - * stack of variable records. + * stack of variables. */ -public class ScopeNode extends Node { +public class ScopeNode extends MemMergeNode { /** * The control is a name that binds to the currently active control @@ -26,40 +26,38 @@ public class ScopeNode extends Node { public static final String ARG0 = "arg"; public static final String MEM0 = "$mem"; - public Node in(Var v) { return in(v._idx); } - - @Override public Type compute() { return Type.BOTTOM; } - @Override public Node idealize() { return null; } - - // All active/live variables in all nested scopes, all run together + // All active/live variables in all nested scopes, all run together. + // Maps 1-to-1 to the _inputs array. public final Ary<Var> _vars; // Lexical scope is typed: public static class Kind { // Basic block scoping - public static class Block extends Kind { } + public static class Block extends Kind { } + // Constructor/initializer block for an allocated struct. + public static class Constructor extends Block { + public Constructor(TypeStruct self) { _self = self; } + public final TypeStruct _self; + } // Function scope - public static class Func extends Kind { } - // Struct definition, mapping types to fields - public static class Define extends Kind { public Define(TypeMemPtr tmp) { _tmp=tmp; } public final TypeMemPtr _tmp; } - // Struct allocation, mapping values to fields - public static class Alloc extends Kind { public Alloc (TypeMemPtr tmp) { _tmp=tmp; } public final TypeMemPtr _tmp; } + public static class Func extends Kind { public Func(String name) { _name=name;} public final String _name; } public int _lexSize; // Number of Vars in this scope } public final Ary<Kind> _kinds; // Lexical scope nesting depth public int depth() { return _kinds._len; } + public Kind klast() { return _kinds.last(); } - // Extra guards; tested predicates and casted results + // Extra guards; tested predicates and cast results private final Ary<Node> _guards; // A new ScopeNode public ScopeNode() { - _type = Type.BOTTOM; - _vars = new Ary<>(Var .class); - _kinds = new Ary<>(Kind .class); - _guards = new Ary<>(Node .class); + super(); + _vars = new Ary<>(Var .class); + _kinds = new Ary<>(Kind.class); + _guards = new Ary<>(Node.class); } @Override public String label() { return "Scope"; } @@ -70,7 +68,7 @@ public class ScopeNode extends Node { int j=1; for( int i=0; i<nIns(); i++ ) { if( j < depth() && i == _kinds.at(j)._lexSize ) { p.p("| "); j++; } - Var v = _vars.at(i); + Var v = var(i); p.p(v._type()); p.p(" "); if( v._final ) p.p("!"); @@ -89,7 +87,7 @@ public class ScopeNode extends Node { public Node ctrl() { return in(0); } - public Node mem() { return in(lookup(MEM0)); } + public Node mem() { return in(1); } public Var var(int i) { return _vars.at(i); } /** @@ -103,7 +101,7 @@ public class ScopeNode extends Node { * @return Node that was bound */ public <N extends Node> N ctrl(N n) { return setDef(0,n); } - public Node mem(Node n) { update(MEM0,n); return n; } + public Node mem(Node n) { return setDef(1,n); } public void push( Kind kind ) { kind._lexSize = _vars.size(); @@ -112,7 +110,11 @@ public class ScopeNode extends Node { // Pop a lexical scope public void pop() { - promote(); // Promote forward references to the next outer scope + promote(null); // Promote forward references to the next outer scope + _pop(); + } + // Pop a scope, no promote FRefs + public void _pop() { int n = _kinds.pop()._lexSize; popUntil(n); // Pop off inputs going out of scope _vars.setLen(n); // Pop off variables going out of scope @@ -121,68 +123,85 @@ public class ScopeNode extends Node { // Look for forward references in the last lexical scope and promote to the // next outer lexical scope. At the last scope declare them an error. - public void promote() { - Kind kind = _kinds.last(); + public void promote(CodeGen code) { + Kind kind = klast(); int n = kind._lexSize; for( int i=n; i<nIns(); i++ ) { Var v = var(i); + Node vn = in(i); if( !v.isFRef() ) continue; - if( depth()==1 ) - throw Parser.error("Undefined name '" + v._name + "'",v._loc); - _vars .swap(n,i); - _inputs.swap(n,i); - v._idx = n; + // Shuffle vars and inputs to move the forward reference to + // *before* the start of the using scope ("as if" it was not + // actually a forward reference). + for( int j=n; j<=i; j++ ) { + Var vtmp = var(j); + Node ntmp = in (j); + v._idx = j; + _vars .set(j,v ); + _inputs.set(j,vn); + v = vtmp; + vn = ntmp; + } kind._lexSize = ++n; } } - // Allocation fields live in the scope immediately outside the constructor - // block. Nested blocks retain that permission; surrounding bindings do not. - public boolean canInit(Var v) { - for( int i=_kinds._len-1; i>0; i-- ) - if( _kinds.at(i) instanceof Kind.Alloc ) - return v._idx >= _kinds.at(i-1)._lexSize && v._idx < _kinds.at(i)._lexSize; - return false; + public boolean inFunction () { return klast() instanceof Kind.Func; } + // Is any enclosing scope a constructor? + public boolean inConstructor() { return constructorSelf() != null; } + // Nearest constructor self type, if any. + public TypeStruct constructorSelf() { + for( int i=depth()-1; i>=0; i-- ) + if( _kinds.at(i) instanceof Kind.Constructor ctor ) + return ctor._self; + else if( _kinds.at(i) instanceof Kind.Func func && FunNode.isInstance(func._name) ) + return ((TypeMemPtr)var(_kinds.at(i)._lexSize).type())._obj; + return null; } - public boolean inConstructor() { return _kinds.last() instanceof Kind.Define; } - public boolean inAllocation () { return _kinds.last() instanceof Kind.Alloc ; } - public boolean inFunction () { return _kinds.last() instanceof Kind.Func ; } - - public Kind kind( Var v ) { + // Find nearest enclosing function scope + public int enclosingFunction() { for( int i=depth()-1; i>=0; i-- ) - if( v._idx >= _kinds.at(i)._lexSize ) - return _kinds.at(i); - throw Utils.TODO(); + if( _kinds.at(i) instanceof Kind.Func func && !FunNode.isInstance(func._name) ) + return i; + throw Utils.TODO("Should not reach here"); } - // Return the kind for the defining scope, or a function scope if found - // first. Block scopes means the variable can be r/w directly in the - // scope, Function scopes require final constants (no capture), and - // Constructor scopes mean an instance variable reference. - - // Walk up-lexical scope looking for defining lexical Kind. - // - Skip any amount of nested block scopes - // - Walking out of a function requires v be a final constant (for now) - - // and we can stop walking. - - // - Walking out of a method and (skipping Blocks) into the matching struct - // is OK, and this is a instance var load. + // Find nearest enclosing function or declaration scope + public int enclosingFuncOrDecl() { + for( int i=depth()-1; i>=0; i-- ) + if( _kinds.at(i) instanceof Kind.Func func ) + return i; + throw Utils.TODO("Should not reach here"); + } - // - Walking out of a method and into the wrong struct is an error; - // including nested structs containing (no nested classes yet) + // Which lexical scope contains this Var? + public int kindx( Var v ) { + for( int i=depth()-1; i>=0; i-- ) + if( v._idx >= _kinds.at(i)._lexSize ) + return i; + return -1; + } - // Returns error, forward-ref, ok containing struct, ok containing function/block. + // Which lexical scope contains this Var? + public Kind kind( Var v ) { + int kx = kindx(v); + return kx == -1 ? null : _kinds.at(kx); + } - public String outOfFunction( Var v ) { - //if( v==null ) return null; // Prolly forward reference - //int i; for( i=_lexSize._len-1; i>=0 && v._idx<_lexSize.at(i); i-- ) - // if( _kinds.at(i)=="{->}" ) return "{->}"; - //return _kinds.at(i); - throw Utils.TODO(); + public int kindFcnx( Var v ) { + for( int i=depth()-1; i>=0; i-- ) + if( v._idx >= _kinds.at(i)._lexSize && _kinds.at(i) instanceof Kind.Func ) + return i; + throw Utils.TODO("Should not reach here"); } + // Which function scope contains this Var? + public Kind kindFcn( Var v ) { + int kx = kindFcnx(v); + return kx == -1 ? null : _kinds.at(kx); + } // Find name in reverse, return an index into _vars or -1. Linear scan // instead of hashtable, but probably doesn't matter until the scan @@ -198,9 +217,9 @@ public class ScopeNode extends Node { * Create a new variable name in the current scope */ public boolean define( String name, Type declaredType, boolean xfinal, Node init, Parser.Lexer loc ) { - assert _kinds.isEmpty() || name.charAt(0)!='$' ; // Later scopes do not define memory + assert _kinds.isEmpty() || name!=MEM0 ; // Later scopes do not define memory if( depth() > 0 ) - for( int i=_vars.size()-1; i>=_kinds.last()._lexSize; i-- ) { + for( int i=_vars.size()-1; i>=klast()._lexSize; i-- ) { Var n = var(i); if( n._name.equals(name) ) { if( !n.isFRef() ) return false; // Double define @@ -208,17 +227,45 @@ public class ScopeNode extends Node { if( !xfinal || !declaredType.isConstant() ) throw fref.err(); // Must be a final constant n.defFRef(declaredType,xfinal,loc); // Declare full correct type, final, source location setDef(n._idx,fref.addDef(init)); // Set FRef to defined; tell parser also + return true; } } - Var v = new Var(nIns(),name,declaredType,xfinal,loc,init==Parser.XCTRL); + Var v = new Var(nIns(),name,declaredType,xfinal,loc,init==CodeGen.CODE.XCTRL); _vars.add(v); // Creating a forward reference - if( init==Parser.XCTRL ) - init = new FRefNode(v).init(); + if( init==CodeGen.CODE.XCTRL ) + //init = new FRefNode(v).init(); + throw Utils.TODO(); addDef(init); return true; } + // Normal lookup was tried and failed. Append a forward ref in the current + // lexical scope. Scope pops promote it outwards "as if" the final constant + // had been declared before the using scope. + + public Var defineFRef( String id, Type t, boolean xfinal, Parser.Lexer loc ) { + Var var = new Var(nIns(),id,t,xfinal,loc,true); + FRefNode fref = new FRefNode(id,loc).init(); + fref._type = fref._con = t; + _vars.add(var); + addDef(fref); + return var; + } + + + // Parser state carries one complete, conservative memory value. Precise + // alias partitions belong to the graph and are introduced by peepholes. + public Node mem( int alias ) { + assert alias == 1; + return in(update(var(1),null)); + } + public void mem( int alias, Node st ) { + assert alias == 1; + update(var(1),st); + } + + /** * Lookup a name in all scopes starting from most deeply nested. * @@ -254,7 +301,7 @@ 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.type(), 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).init()); setDef(v._idx,old); } //assert !v._final || st==null; @@ -292,9 +339,15 @@ public class ScopeNode extends Node { n.keep(); dup.addDef(ctrl()); // Control input is just copied - // Memory is one binding, with the same lazy loop Phi as scalar names. - for( int i=1; i<nIns(); i++ ) - dup.addDef(loop && !_vars.at(i)._final ? this : in(i)); + // Memory is one ordinary parser-state value. At loop heads the + // Scope sentinel triggers the same lazy-Phi machinery as variables. + dup.addDef(loop ? this : mem()); + + // Copy of other inputs + for( int i=2; i<nIns(); i++ ) + // For lazy phis on loops we use a sentinel + // that will trigger phi creation on update + dup.addDef(loop && !var(i)._final ? this : in(i)); return dup; } @@ -308,14 +361,17 @@ public class ScopeNode extends Node { */ public RegionNode mergeScopes(ScopeNode that, Parser.Lexer loc) { RegionNode r = ctrl(new RegionNode(loc,null,ctrl(), that.ctrl()).keep()); - _merge(that,r); + this._merge(that,r); that.kill(); // Kill merged scope CodeGen.CODE.add(r); return r.unkeep(); } - private void _merge(ScopeNode that, RegionNode r) { - for( int i = 1; i < nIns(); i++) + public void _merge(ScopeNode that, RegionNode r) { + _merge(that,r,nIns()); + } + public void _merge(ScopeNode that, RegionNode r, int max ) { + for( int i = 1; i < max; i++) 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 @@ -328,18 +384,38 @@ public class ScopeNode extends Node { // Balance arms of an IF. Extra lonely defs are thrown: "if(pred) int x;". // Forward refs are copied to the other side, "as if" they were there all along. + // 'this' scope is the default, 'scope' might have frefs. public void balanceIf( ScopeNode scope ) { - for( int i = nIns(); i < scope.nIns(); i++ ) { + if( nIns()==scope.nIns() ) + return; // Fast-path cutout + int kidx = enclosingFunction(); + assert _kinds.at(kidx) == scope._kinds.at(kidx); + if( kidx==0 ) kidx = 1; + for( int i = _kinds.at(kidx-1)._lexSize; i < scope.nIns(); i++ ) { Var n = scope.var(i); + if( i<nIns() && var(i)==n ) continue; if( n.isFRef() ) { // RHS has forward refs - _vars.add(n); // Copy to LHS - addDef(scope.in(i)); + _vars.insert(n,i); + insertDef(i,scope.in(i)); } else throw Parser.error("Cannot define a '"+n._name+"' on one arm of an if",n._loc); } } + public void balanceLoopFRefs( ScopeNode scope ) { + for( int i = nIns(); i < scope.nIns(); i++ ) { + Var n = scope.var(i); + if( n.isFRef() ) { // Loop body has forward refs + Var v = new Var(nIns(),n._name,n.type(),n._final,n._loc,true); + v._uninit = n._uninit; + _vars.add(v); + addDef(scope.in(i)); + } + } + } + + // ------------------------------------------------ // peephole the backedge scope into this loop head scope // We set the second input to the phi from the back edge (i.e. loop body) public void endLoop(ScopeNode back, ScopeNode exit ) { @@ -347,49 +423,108 @@ public class ScopeNode extends Node { assert ctrl instanceof LoopNode loop && loop.inProgress(); ctrl.setDef(2,back.ctrl()); - _endLoop(this,back,exit); + this._endLoop( this, back, exit); back.kill(); // Loop backedge is dead // Now one-time do a useless-phi removal - _useless(); + this._useless(); } // Fill in the backedge of any inserted Phis void _endLoop( ScopeNode scope, Node back, Node exit ) { for( int i=1; i<nIns(); i++ ) { - if( _vars.at(i)._final ) continue; // Final vars did not get modified in the loop - if( _vars.at(i).type().isHighOrConst() ) continue; // Cannot lift higher than a constant, so no Phi - if( back.in(i) != scope ) { - PhiNode phi = (PhiNode)in(i); + if( var(i)._final ) continue; // Final vars did not get modified in the loop + Node n = in(i); + if( var(i).type().isHighOrConst() && !(n instanceof PhiNode phi && phi.inProgress()) ) { // Cannot lift higher than a constant, so no Phi + Node con = ConstantNode.make(var(i).type()).init(); + n.subsume(con); + n = con; + } else if( back.in(i) != scope ) { + PhiNode phi = (PhiNode)n; assert phi.region()==scope.ctrl() && phi.in(2)==null; phi.setDef(2,back.in(i)); // Fill backedge } if( exit.in(i) == scope ) // Replace a lazy-phi on the exit path also - exit.setDef(i,in(i)); - } - } - - - // Now one-time do a useless-phi removal - void _useless( ) { - for( int i=1; i<nIns(); i++ ) { - if( in(i) instanceof PhiNode phi ) { - // Do an eager useless-phi removal - Node in = phi.peephole(); - CodeGen.CODE.addAll(phi._outputs); - phi.moveDepsToWorklist(); - if( in != phi ) { - if( !phi.iskeep() ) // Keeping phi around for parser elsewhere - phi.subsume(in); - setDef(i,in); // Set the update back into Scope - } - } + exit.setDef(i,n); } } + // ------------------------------------------------ // Up-casting: using the results of an If to improve a value. // E.g. "if( ptr ) ptr.field;" is legal because ptr is known not-null. - public void addGuards( Node ctrl, Node pred, boolean invert ) { - assert ctrl instanceof CFGNode; + // + // This operation is lexical, not a full semantic theorem prover, and thus + // its behavior changes the language spec. Optimizations that hide the + // lexical structure (e.g. constant folding control flow) can hide what is + // guarded or how the guard is applied, making it somewhat fragile. Several + // good use cases are covered here, but not everything you might like. + // + // Simple lexical facts work well: + // + // ``` + // if( ptr ) + // return ptr.field; // `ptr` is guarded non-null here. + // + // if( a && a.ptr ) + // return a.ptr.x; // `a` is guarded while parsing the RHS load, + // // and remains guarded on the true arm. + // ``` + // + // Short-circuit expressions are lowered as nested Phis. We recursively + // decompose the recognized Phi shape, so chains such as: + // + // ``` + // if( x && y && z ) + // use(x,y,z); + // ``` + // + // discover the nested `x && y` and then `x`, `y`, and `z`; this is not + // merely a one-level lookup. Likewise, nested tests carry lexical guards + // inwards: + // + // ``` + // if( x && y ) + // if( z && a ) + // if( x.ptr && z.ptr ) + // ... + // ``` + // + // Here `x` is already guarded while parsing the outer true arm, `z` while + // parsing the inner true arm, and both are available before the matching + // loads. The later post-test decomposition is just a convenience for + // values still schedulable at the post-test control. + // + // The hard limit is that a semantic implication is not always a + // schedulable Node. For `(x && y)`, the true side implies that `y` was + // true, but `y` might be a value computed only on the RHS control arm: + // + // ``` + // val ptr = ...; + // if( ptr && (ptr=fcn() ? 0 : arg ) {} + // ``` + // + // A Guard pinned after the Phi merge and using the branch-local `ptr` + // value would give that value a use above its defining arm. GCM then has + // no legal block between the value's early control and the LCA of its + // uses. Thus `_addGuards` first checks that the predicate's effective + // early CFG dominates the control where the Guard would be pinned. If it + // does not, we skip that guard even if the fact is semantically true. + // + // A more complete answer would need a richer logical/proof node, or would + // need to rematerialize predicates on the guarded path instead of using + // branch-local nodes directly. Plain GuardNodes are intentionally kept to + // facts represented by values already available at the guard control. + // + // TODO: Make this more robust for shapes like: + // ``` + // if( !ary || !ary# ) exit(); // facts about ary are lost, despite the early exit + // for( ...; ary# ) ...; + // ``` + // Here the guard ends up guarding the whole expression (both ary and ary# + // are not-null), but loses that ary is not-null. A better answer might be + // a dedicated logical expression node, or some sort of gather-of-checked + // values to Guard post-test. + + public void addGuards( CFGNode ctrl, Node pred, boolean invert ) { _guards.add(ctrl); // Marker between guard sets // add pred & its cast to the normal input list, with special Vars if( pred==null || pred.isDead() ) @@ -397,10 +532,11 @@ public class ScopeNode extends Node { _addGuards(ctrl,pred,invert); } - private void _addGuards( Node ctrl, Node pred, boolean invert ) { + private void _addGuards( CFGNode ctrl, Node pred, boolean invert ) { if( pred==null || pred.isDead() ) return; - if( !availableAt(pred,(CFGNode)ctrl,new BitSet()) ) + CFGNode early = CFGNode.earlyCFG(pred); + if( early != null && !early.dominates(ctrl,null) ) return; // A single negation is handled below. For !!p (including p != null) // or a negated short-circuit Phi, also discover the underlying facts. @@ -410,8 +546,10 @@ public class ScopeNode extends Node { _addGuards(ctrl,not.in(1),!invert); pred.unkeep(); } - // A false || or true && proves both operands. Only guard values - // available at this control, not ones confined to the RHS branch. + // Short-circuit logic is represented by a Phi. For `a || b` being + // false, or `a && b` being true, both individual operands have the + // same proven value as the whole expression. The "skipped RHS" path + // is the Region input whose Phi value is the controlling If predicate. if( pred instanceof PhiNode phi && phi.nIns()==3 && phi.region() instanceof RegionNode r && r.nIns()==3 ) for( int i=1; i<3; i++ ) if( r.in(i) instanceof CProjNode prj && prj.ctrl() instanceof IfNode iff ) { @@ -425,38 +563,19 @@ public class ScopeNode extends Node { // Invert the If conditional if( invert ) pred = pred instanceof NotNode not ? not.in(1) : CodeGen.CODE.add(new NotNode(pred).peephole()); + Node zeroPred = pred instanceof NotNode not ? not.in(1) : null; // This is a zero/null test. // Compute the positive test type. - Type tnz = pred._type.nonZero(); - if( tnz!=null ) - _addGuard(tnz,ctrl,pred); + _addGuard(true,ctrl,pred); // Compute the negative test type. - if( pred instanceof NotNode not ) { - Node npred = not.in(1); - Type tzero = npred._type.makeZero(); - _addGuard(tzero,ctrl,npred); - } - } - - // A Phi's value is available at its Region. Other data nodes require all - // their inputs, including pinned control, to dominate the proposed guard. - private static boolean availableAt(Node n, CFGNode ctrl, BitSet visit) { - if( n==null || n instanceof ConstantNode || visit.get(n._nid) ) return true; - visit.set(n._nid); - if( n instanceof PhiNode phi ) n = phi.region(); - if( n instanceof CFGNode cfg ) { - for( CFGNode dom=ctrl; dom!=null; dom=dom.idom() ) - if( dom==cfg ) return true; - return false; - } - for( Node def : n._inputs ) - if( !availableAt(def,ctrl,visit) ) return false; - return true; + if( zeroPred != null ) + _addGuard(false,ctrl,zeroPred); } private static Node shortCircuitSkippedPred( Node val, Node pred, CProjNode prj, boolean invert ) { - if( val == null ) return null; + if( val == null ) + return null; if( val == pred ) return (prj._idx==0)==invert ? val : null; if( val instanceof NotNode not && not.in(1)==pred ) @@ -468,19 +587,20 @@ public class ScopeNode extends Node { return null; } - private void _addGuard(Type guard, Node ctrl, Node pred) { - Type tcast = guard.join(pred._type); - if( tcast != pred._type && !tcast.isHigh() ) { - Node cast = new CastNode(tcast,ctrl,pred.keep()).peephole().keep(); + private void _addGuard(boolean nonZero, Node ctrl, Node pred) { + Node guard = new GuardNode(nonZero,ctrl,pred).peephole(); + if( guard != pred ) { + pred.keep(); + guard.keep(); _guards.add(pred); - _guards.add(cast); - replace(pred,cast); + _guards.add(guard); + replace(pred,guard,nonZero); } } // Remove matching pred/cast pairs from this guarded region. - public ScopeNode removeGuards( Node ctrl ) { + public void removeGuards( Node ctrl ) { assert ctrl instanceof CFGNode; // Pop the guards up to this region's marker. while( true ) { @@ -490,7 +610,6 @@ public class ScopeNode extends Node { g .unkill(); // Pop/kill cast _guards.pop().unkill(); // Pop/kill pred } - return this; } // If we find a guarded instance of pred, replace with the upcasted version @@ -520,11 +639,65 @@ public class ScopeNode extends Node { } - private void replace( Node old, Node cast ) { + private void replace( Node old, Node cast, boolean nonZero ) { assert old!=null && old!=cast; for( int i=0; i<nIns(); i++ ) - if( in(i)==old ) + if( in(i)==old || nonZero && nullCheckedPhi(in(i),old) ) setDef(i,cast); } + private static boolean nullCheckedPhi( Node n, Node old ) { + if( !(n instanceof PhiNode phi) || phi.nIns()!=3 ) + return false; + if( phi.in(1)==null || phi.in(2)==null ) + return false; + int zero = phi.in(1)._type == phi.in(1)._type.makeZero() ? 1 : + phi.in(2)._type == phi.in(2)._type.makeZero() ? 2 : -1; + if( zero == -1 ) + return false; + Node val = phi.in(3-zero); + return val==old || + val instanceof GuardNode guard && guard._nonZero && guard.in(1)==old; + } + + // ------------------------------------------------------------------------ + // Insert a top-level public external symbol, "as-if" some #include/import + // was executed at the top of tile. + public Var insertExtern( ExternNode ext ) { + // Size of top-level scope + int lexSize = _kinds.at(0)._lexSize; + Var var = new Var(lexSize,ext._extern,ext._con,true,null); + insert(var,ext,0); + return var; + } + + // ------------------------------------------------------------------------ + // Insert a Var with Node n in the lex scope just prior to kidx + private void insert( Var var, Node n, int kidx ) { + // Insert just prior to scope kidx + int nidx = _kinds.at(kidx)._lexSize; + _vars.insert(var,nidx); + insertDef(nidx,n); + // All outer Kinds lexical offsets bump by one + for( int i = kidx; i < depth(); i++ ) + _kinds.at(i)._lexSize++; + // All Vars outside the innermost lexical scope bump out one + for( int i=nidx+1; i<_vars._len; i++ ) + var(i)._idx++; + } + + // Save the existing Node state to an array + public Node[] save() { + Node[] olds = new Node[nIns()]; + for( int i=0; i<nIns(); i++ ) + olds[i] = in(i)==null ? null : in(i).keep(); + return olds; + } + + // Restore saved Node state back into scope + public void restore( Node[] olds ) { + assert olds.length<=nIns(); + for( int i=0; i<olds.length; i++ ) + setDef(i,olds[i]==null ? null : olds[i].unkeep()); + } } |