Split out incomplete type analysis

4 files changed, 18 insertions, 3 deletions

diff --git a/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java b/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
index e5ad596d..3695c6fc 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
@@ -168,6 +168,12 @@ public class CodeGen {
     // the return is not part of the match).
     private final HashMap<TypeFunPtr,FunNode> _linker = new HashMap<>();
 
+    // Native symbols belong to function identities, not to one ExternNode.
+    // Selection and spill copies can turn that node into an ordinary constant.
+    private final HashMap<TypeFunPtr,String> _externs = new HashMap<>();
+    public void externFunc(TypeFunPtr tfp, String name) { _externs.put(tfp.makeFrom(Type.BOTTOM),name); }
+    public String externFunc(TypeFunPtr tfp) { return _externs.get(tfp.makeFrom(Type.BOTTOM)); }
+
     // Parser object
     public final Parser P;
 
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/codegen/Encoding.java b/chapter22/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
index aad19090..1ed2ed30 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
@@ -135,6 +135,10 @@ public class Encoding implements com.seaofnodes.isa.CodeSink {
     }
     public Encoding relo( ConstantNode con ) {
         TypeFunPtr tfp = (TypeFunPtr)con._con;
+        // A native address has no local FunNode. Keep its symbol even after
+        // selection or a spill copy has replaced the original ExternNode.
+        String name = _code.externFunc(tfp);
+        if( name!=null ) return external(con,name);
         _internals.put(con,_code.link(tfp));
         return this;
     }
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java b/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java
index 093cc2cb..bfd637dd 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/node/ExternNode.java
@@ -13,7 +13,11 @@ import java.util.BitSet;
 
 public class ExternNode extends ConstantNode {
     public final String _extern;
-    public ExternNode(Type t, String ex) { super(t); _extern = ex; }
+    public ExternNode(Type t, String ex) {
+        super(t);
+        _extern = ex;
+        if( t instanceof TypeFunPtr tfp ) CodeGen.CODE.externFunc(tfp,ex);
+    }
 
     @Override public String  label() { return "#"+_con+":"+_extern; }
 
diff --git a/chapter22/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java b/chapter22/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
index 720a14c1..62b50cef 100644
--- a/chapter22/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
+++ b/chapter22/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
@@ -38,8 +38,9 @@ public class TFPARM extends ConstantNode implements MachNode, RIPRelSize {
             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));
+            // ADRP splits a signed page offset into two unsigned bit fields.
+            // Mask the high field too, including for an address below this PC.
+            enc.patch4(opStart, Arm64.adrp(1, adrp_delta & 0b11, 0b10000, (adrp_delta >> 2) & 0x7FFFF, rpc));
             // low 12 bits via add
             enc.patch4(opStart+4, Arm64.imm_inst_l(Arm64.OPI_ADD, delta & 0xfff, rpc));
         } else {