[x64] Use vmovapd and vmovsd 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 059b576beaa42d52765c8b383762199a0a14e392..5789782d09f24ef74183a0c7a89b39c607056e49 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -2685,6 +2685,7 @@ void Assembler::pinsrd(XMMRegister dst, const Operand& src, int8_t imm8) {
 
 
 void Assembler::movsd(const Operand& dst, XMMRegister src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit(0xF2);  // double
   emit_optional_rex_32(src, dst);
@@ -2695,6 +2696,7 @@ void Assembler::movsd(const Operand& dst, XMMRegister src) {
 
 
 void Assembler::movsd(XMMRegister dst, XMMRegister src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit(0xF2);  // double
   emit_optional_rex_32(dst, src);
@@ -2705,6 +2707,7 @@ void Assembler::movsd(XMMRegister dst, XMMRegister src) {
 
 
 void Assembler::movsd(XMMRegister dst, const Operand& src) {
+  DCHECK(!IsEnabled(AVX));
   EnsureSpace ensure_space(this);
   emit(0xF2);  // double
   emit_optional_rex_32(dst, src);
@@ -3458,6 +3461,15 @@ void Assembler::vfmass(byte op, XMMRegister dst, XMMRegister src1,
 }
 
 
+void Assembler::vmovapd(XMMRegister dst, XMMRegister src) {
+  DCHECK(IsEnabled(AVX));
+  EnsureSpace ensure_space(this);
+  emit_vex_prefix(dst, xmm0, src, kLIG, k66, k0F, kWIG);
+  emit(0x28);
+  emit_sse_operand(dst, src);
+}
+
+
 void Assembler::vucomisd(XMMRegister dst, XMMRegister src) {
   DCHECK(IsEnabled(AVX));
   EnsureSpace ensure_space(this);