[x64] Make use of vucomiss and vucomisd when AVX is enabled.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index d23390f68be8bdc265769debfedcf28c620f91a2..f8bcf0a3b6fe8b18ad0614bf679e9236b8017f9d 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -2931,6 +2931,7 @@ void Assembler::sqrtss(XMMRegister dst, const Operand& src) {
 
 
 void Assembler::ucomiss(XMMRegister dst, XMMRegister src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit_optional_rex_32(dst, src);
   emit(0x0f);
@@ -2940,6 +2941,7 @@ void Assembler::ucomiss(XMMRegister dst, XMMRegister src) {
 
 
 void Assembler::ucomiss(XMMRegister dst, const Operand& src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit_optional_rex_32(dst, src);
   emit(0x0f);
@@ -3366,6 +3368,7 @@ void Assembler::sqrtsd(XMMRegister dst, const Operand& src) {
 
 
 void Assembler::ucomisd(XMMRegister dst, XMMRegister src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit(0x66);
   emit_optional_rex_32(dst, src);
@@ -3376,6 +3379,7 @@ void Assembler::ucomisd(XMMRegister dst, XMMRegister src) {
 
 
 void Assembler::ucomisd(XMMRegister dst, const Operand& src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit(0x66);
   emit_optional_rex_32(dst, src);