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

src/x64/disasm-x64.cc

Index: src/x64/disasm-x64.cc
diff --git a/src/x64/disasm-x64.cc b/src/x64/disasm-x64.cc
index 82bc6ef93b932933c0219a5ae5aab277dc4210f8..876950ae7cb1ced9e9bf08add28a43c1ca964220 100644
--- a/src/x64/disasm-x64.cc
+++ b/src/x64/disasm-x64.cc
@@ -1098,6 +1098,12 @@ int DisassemblerX64::TwoByteOpcodeInstruction(byte* data) {
         AppendToBuffer("%s,", NameOfXMMRegister(regop));
         current += PrintRightXMMOperand(current);
       }
+    } else if (opcode == 0x12) {
+      // movddup xmm1, xmm2/m64
+      int mod, regop, rm;
+      get_modrm(*current, &mod, &regop, &rm);
+      AppendToBuffer("movddup %s,", NameOfXMMRegister(regop));
+      current += PrintRightXMMOperand(current);
     } else if (opcode == 0x2A) {
       // CVTSI2SD: integer to XMM double conversion.
       int mod, regop, rm;