Use SSE2 instructions when available on ia32 platform.

src/ia32/assembler-ia32.cc

Index: src/ia32/assembler-ia32.cc
===================================================================
--- src/ia32/assembler-ia32.cc	(revision 2860)
+++ src/ia32/assembler-ia32.cc	(working copy)
@@ -721,10 +721,10 @@
   ASSERT(CpuFeatures::IsEnabled(CpuFeatures::CMOV));
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
-  UNIMPLEMENTED();
-  USE(cc);
-  USE(dst);
-  USE(src);
+  // Opcode: 0f 40 + cc /r
+  EMIT(0x0F);
+  EMIT(0x40 + cc);
+  emit_operand(dst, src);
 }
 
 
@@ -866,6 +866,13 @@
 }
 
 
+void Assembler::cmp(const Operand& op, Handle<Object> handle) {
+  EnsureSpace ensure_space(this);
+  last_pc_ = pc_;
+  emit_arith(7, op, Immediate(handle));
+}
+
+
 void Assembler::cmpb_al(const Operand& op) {
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
@@ -1947,6 +1954,17 @@
 }
 
 
+void Assembler::comisd(XMMRegister dst, XMMRegister src) {
+  ASSERT(CpuFeatures::IsEnabled(CpuFeatures::SSE2));
+  EnsureSpace ensure_space(this);
+  last_pc_ = pc_;
+  EMIT(0x66);
+  EMIT(0x0F);
+  EMIT(0x2F);
+  emit_sse_operand(dst, src);
+}
+
+
 void Assembler::movdbl(XMMRegister dst, const Operand& src) {
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;