Chapter 25: Modules, Separate Compilation, and SSA Constructionlinear

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>

1 files changed, 62 insertions, 6 deletions

diff --git a/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java b/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java
index 43242c32..82053fd8 100644
--- a/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java
+++ b/src/main/java/com/seaofnodes/simple/node/FunPtrNode.java
@@ -1,12 +1,68 @@
 package com.seaofnodes.simple.node;
 
-import com.seaofnodes.simple.type.TypeFunPtr;
+import com.seaofnodes.print.ExprPrinter;
 
-// 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);
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.type.*;
+import com.seaofnodes.simple.util.BAOS;
+
+import java.util.HashMap;
+import java.util.IdentityHashMap;
+
+// Constant function pointer whose type follows the callee signature.
+public class FunPtrNode extends TypeNode {
+    public FunPtrNode(TypeFunPtr tfp, StartNode start, ReturnNode ret) {
+        super(tfp,start,ret);
+    }
+    public FunPtrNode(FunPtrNode fptr) { super(fptr); }
+    @Override public Tag serialTag() { return Tag.FunPtr; }
+    @Override public void packed(BAOS baos, HashMap<String,Integer> strs, HashMap<Type,Integer> types, IdentityHashMap<Node,Integer> anodes) {
+        baos.packed2(types.get(_con));
+    }
+    static Node make(BAOS bais, Type[] types) {
+        return new FunPtrNode((TypeFunPtr)types[bais.packed2()],null,null);
     }
     public ReturnNode ret() { return (ReturnNode)in(1); }
+    public FunNode fun() { return ret().fun(); }
+
+    @Override public String label() { return "#"+_con; }
+    @Override public Node copy() {
+        FunPtrNode fptr = new FunPtrNode((TypeFunPtr)_con,null,null);
+        fptr._type = _type;
+        return fptr;
+    }
+
+    @Override
+    protected ExprPrinter<Node> _print1(ExprPrinter<Node> p) {
+        FunNode fun = CodeGen.CODE._link(((TypeFunPtr)_con).fidx());
+        return fun!=null && fun._name!=null
+            ? p.p("{ ").p(fun._name).p("}")
+            : p.p(_con);
+    }
+
+    @Override public boolean isConst() { return true; }
+    @Override public Type compute() {
+        ReturnNode ret = ret();
+        if( ret == null ) return _con;
+        if( !(ret._type instanceof TypeTuple tt) ) return ret._type.oob();
+        TypeFunPtr tfp = ret.fun().sig();
+        // Both the sig and the return value must be true, so JOIN both
+        Type tret = tfp._ret.join(tt.ret());
+        return tfp.makeFrom(tret);
+    }
+    @Override public Node idealize() {
+        ReturnNode ret = ret();
+        if( ret==null ) return null;
+        // Function died (never executed), but fcn ptr is alive.
+        // Can be checked for null, or for unequals another FunPtr.
+        FunNode fun = addDep(ret.fun());
+        TypeFunPtr sig = fun.sig();
+        if( sig != _con )
+            { liftType(sig);  return this; }
+        // TODO: If the function body dies but this value remains live only as
+        // a null/equality sentinel, preserve the identity without the Return.
+        if( fun.isDead() )
+            { setDef(1,null); liftType(sig.makeFrom(Type.TOP)); return this; }
+        return null;
+    }
 }