Larger frame encodings

2 files changed, 9 insertions, 8 deletions

diff --git a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/FunX86.java b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/FunX86.java
index 106d1255..a0747025 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/FunX86.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/FunX86.java
@@ -29,14 +29,14 @@ public class FunX86 extends FunNode implements MachNode {
         int sz = Math.max(_maxSlot - _maxArgSlot,0);
         // If non-leaf function, pad to 16b
         if( _hasCalls ) sz = ((sz+1) & -2)+1;
-        assert x86_64_v2.imm8(sz*8);
         _frameAdjust = (short)sz;
         if( sz == 0 ) return; // Skip if no frame adjust
 
         // opcode: 0x83, addi rsp with immediate 8
-        enc.add1( x86_64_v2.REX_W ).add1( 0x83 );
+        enc.add1( x86_64_v2.REX_W ).add1( x86_64_v2.imm8(sz*8) ? 0x83 : 0x81 );
         enc.add1( x86_64_v2.modrm(x86_64_v2.MOD.DIRECT, 0b101, x86_64_v2.RSP) );
-        enc.add1(sz*8);
+        if( x86_64_v2.imm8(sz*8) )  enc.add1(sz*8);
+        else                        enc.add4(sz*8);
     }
 
     @Override public void asm(CodeGen code, SB sb) {
diff --git a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RetX86.java b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RetX86.java
index ca9f148c..0b8f88a3 100644
--- a/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RetX86.java
+++ b/chapter21/src/main/java/com/seaofnodes/simple/node/cpus/x86_64_v2/RetX86.java
@@ -18,11 +18,12 @@ public class RetX86 extends ReturnNode implements MachNode {
     @Override public RegMask regmap(int i) { return x86_64_v2.retMask(_fun.sig(),i); }
     @Override public RegMask outregmap() { return null; }
     @Override public void encoding( Encoding enc ) {
-        int frameAdjust = ((FunX86)fun())._frameAdjust;
-        if( frameAdjust > 0 ) {
-            enc.add1( x86_64_v2.REX_W ).add1( 0x83 );
-            enc.add1( x86_64_v2.modrm(x86_64_v2.MOD.DIRECT, 0, x86_64_v2.RSP) );
-            enc.add1(frameAdjust*8);
+        int sz = ((FunX86)fun())._frameAdjust;
+        if( sz != 0 ) {
+            enc.add1( x86_64_v2.REX_W ).add1( x86_64_v2.imm8(sz*8) ? 0x83 : 0x81 );
+            enc.add1( x86_64_v2.modrm(x86_64_v2.MOD.DIRECT, 0b000, x86_64_v2.RSP) );
+            if( x86_64_v2.imm8(sz*8) )  enc.add1(sz*8);
+            else                        enc.add4(sz*8);
         }
         enc.add1(0xC3);
     }