X64: Adding macro to load double from memory, and use SSE3 instruction if present.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 339420679184b15ead2d8a4921d07368eeb86106..26c6e3324b20102565245cbb7f5bc50fd38c0bee 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -2260,7 +2260,7 @@ void MacroAssembler::LeaveExitFrame(bool save_doubles) {
     int offset = -2 * kPointerSize;
     for (int i = 0; i < XMMRegister::kNumAllocatableRegisters; i++) {
       XMMRegister reg = XMMRegister::FromAllocationIndex(i);
-      movsd(reg, Operand(rbp, offset - ((i + 1) * kDoubleSize)));
+      LoadDbl(reg, Operand(rbp, offset - ((i + 1) * kDoubleSize)));
     }
   }
   // Get the return address from the stack and restore the frame pointer.
@@ -2894,6 +2894,16 @@ void MacroAssembler::CallCFunction(Register function, int num_arguments) {
 }
 
 
+void MacroAssembler::LoadDbl(XMMRegister dst, const Operand& src) {
+  if (CpuFeatures::IsSupported(SSE3)) {
+    CpuFeatures::Scope enable(SSE3);
+    movddup(dst, src);
+  } else {
+    movsd(dst, src);
+  }
+}
+
+
 CodePatcher::CodePatcher(byte* address, int size)
     : address_(address),
       size_(size),