Shorter opcodes in ia32 in some cases where register is wrapped in an operand.

src/ia32/assembler-ia32.cc

Index: src/ia32/assembler-ia32.cc
diff --git a/src/ia32/assembler-ia32.cc b/src/ia32/assembler-ia32.cc
index b4eb0658a626939113e555c44e5e7fdf023e3655..b9e8ed9b067202e35cbcbf810d705a85bdaf643b 100644
--- a/src/ia32/assembler-ia32.cc
+++ b/src/ia32/assembler-ia32.cc
@@ -457,6 +457,10 @@ void Assembler::push(Register src) {
 
 
 void Assembler::push(const Operand& src) {
+  if (src.is_reg_only()) {
+    push(src.reg());
+    return;
+  }
   EnsureSpace ensure_space(this);
   EMIT(0xFF);
   emit_operand(esi, src);
@@ -478,6 +482,10 @@ void Assembler::pop(Register dst) {
 
 
 void Assembler::pop(const Operand& dst) {
+  if (dst.is_reg_only()) {
+    pop(dst.reg());
+    return;
+  }
   EnsureSpace ensure_space(this);
   EMIT(0x8F);
   emit_operand(eax, dst);
@@ -560,6 +568,10 @@ void Assembler::mov(Register dst, Handle<Object> handle) {
 
 
 void Assembler::mov(Register dst, const Operand& src) {
+  if (src.is_reg_only()) {
+    mov(dst, src.reg());
+    return;
+  }
   EnsureSpace ensure_space(this);
   EMIT(0x8B);
   emit_operand(dst, src);
@@ -865,6 +877,10 @@ void Assembler::dec(Register dst) {
 
 
 void Assembler::dec(const Operand& dst) {
+  if (dst.is_reg_only()) {
+    dec(dst.reg());
+    return;
+  }
   EnsureSpace ensure_space(this);
   EMIT(0xFF);
   emit_operand(ecx, dst);
@@ -920,6 +936,10 @@ void Assembler::inc(Register dst) {
 
 
 void Assembler::inc(const Operand& dst) {
+  if (dst.is_reg_only()) {
+    inc(dst.reg());
+    return;
+  }
   EnsureSpace ensure_space(this);
   EMIT(0xFF);
   emit_operand(eax, dst);