Split out incomplete type analysis

5 files changed, 72 insertions, 3 deletions

diff --git a/chapter23/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java b/chapter23/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
index e332146f..0e4ae3cb 100644
--- a/chapter23/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
+++ b/chapter23/src/main/java/com/seaofnodes/simple/codegen/CodeGen.java
@@ -171,6 +171,12 @@ 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/chapter23/src/main/java/com/seaofnodes/simple/codegen/Encoding.java b/chapter23/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
index 5099c02a..5c28e85b 100644
--- a/chapter23/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
+++ b/chapter23/src/main/java/com/seaofnodes/simple/codegen/Encoding.java
@@ -138,6 +138,10 @@ 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/chapter23/src/main/java/com/seaofnodes/simple/node/ExternNode.java b/chapter23/src/main/java/com/seaofnodes/simple/node/ExternNode.java
index ccbcfc66..7a26e2e9 100644
--- a/chapter23/src/main/java/com/seaofnodes/simple/node/ExternNode.java
+++ b/chapter23/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/chapter23/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java b/chapter23/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
index 98a56089..2c41dc57 100644
--- a/chapter23/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
+++ b/chapter23/src/main/java/com/seaofnodes/simple/node/cpus/arm/TFPARM.java
@@ -39,8 +39,9 @@ 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 {
diff --git a/chapter23/src/test/java/com/seaofnodes/simple/NativeAddressTest.java b/chapter23/src/test/java/com/seaofnodes/simple/NativeAddressTest.java
new file mode 100644
index 00000000..6d21ca5f
--- /dev/null
+++ b/chapter23/src/test/java/com/seaofnodes/simple/NativeAddressTest.java
@@ -0,0 +1,54 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.codegen.Encoding;
+import com.seaofnodes.isa.eval.EvalArm64;
+import com.seaofnodes.isa.eval.EvalRisc5;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class NativeAddressTest {
+    @Test public void testReturnedNativeAddress() throws IOException {
+        Path dir = Path.of("build/objs");
+        Files.createDirectories(dir);
+        Files.writeString(dir.resolve("nativeAddress.smp"), """
+            val getAbs = { ->
+                { i32 -> i32 } abs = "C";
+                return abs;
+            };
+            """);
+        Files.writeString(dir.resolve("nativeAddress.c"), """
+            typedef int (*func)(int);
+            extern func getAbs(void);
+            int main(void) {
+                func f = getAbs();
+                return f(-7) != 7 || f(9) != 9;
+            }
+            """);
+        TestC.run("build/objs", "nativeAddress", "", -1);
+    }
+
+    @Test public void testEmulatedNativeAddress() throws IOException {
+        // No native call: return the address itself, patched to the emulator's
+        // known write entry. Both ports share Encoding's symbol lookup.
+        String src = "{ int -> int } write = \"C\"; return write;";
+        for( String cpu : new String[]{"arm","riscv"} ) {
+            CodeGen code = new CodeGen(src).driver(cpu,"SystemV",null);
+            byte[] bits = code._encoding.bits();
+            byte[] image = new byte[1<<20];
+            System.arraycopy(bits,0,image,0,bits.length);
+            if( cpu.equals("arm") ) {
+                EvalArm64 eval = new EvalArm64(image,1<<16);
+                assertEquals(0,eval.step(100));
+                assertEquals(Encoding.SENTINEL_WRITE,eval.regs[0]);
+            } else {
+                EvalRisc5 eval = new EvalRisc5(image,1<<16);
+                assertEquals(0,eval.step(100));
+                assertEquals(Encoding.SENTINEL_WRITE,eval.regs[10]);
+            }
+        }
+    }
+}