Fix ch21 MulIX86 encoding

1 files changed, 31 insertions, 5 deletions

diff --git a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java
index a9a83fb7..3c00b2e8 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/MulIX86.java
@@ -1,11 +1,37 @@
 package com.seaofnodes.simple.node.cpus.x86_64_v2;
 
-import com.seaofnodes.simple.node.Node;
+import com.seaofnodes.simple.SB;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.codegen.*;
 
-public class MulIX86 extends ImmX86 {
-    MulIX86( Node add, int imm ) { super(add,imm); }
+public class MulIX86 extends MachConcreteNode implements MachNode {
+    final int _imm;
+    MulIX86( Node mul, int imm ) {
+        super(mul);
+        _inputs.pop();          // Pop the constant input
+        _imm = imm;             // Record the constant
+    }
     @Override public String op() { return "muli"; }
     @Override public String glabel() { return "*"; }
-    @Override int opcode() { return 0x69; }
-    @Override int mod() { return 0; }
+    @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.
+    @Override public final void encoding( Encoding enc ) {
+        short dst = enc.reg(this ); // Also src1 in this chapter
+        short src = enc.reg(in(1));
+        enc.add1(x86_64_v2.rex(dst, src, 0));
+        // opcode; 0x69 or 0x6B
+        enc.add1( 0x69 + (x86_64_v2.imm8(_imm) ? 2 : 0) );
+        enc.add1( x86_64_v2.modrm(x86_64_v2.MOD.DIRECT, dst, src) );
+        // immediate(4 bytes) 32 bits or (1 byte)8 bits
+        if( x86_64_v2.imm8(_imm) ) enc.add1(_imm);
+        else                       enc.add4(_imm);
+    }
+    // General form: "muli  dst = src * #imm"
+    @Override public void asm(CodeGen code, SB sb) {
+        sb.p(code.reg(this)).p(" = ").p(code.reg(in(1))).p(" * #").p(_imm);
+    }
 }