Optionally use 31-bits SMI value for 64-bit system

src/x64/disasm-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1074 matching lines @@
         AppendToBuffer("movdqa ");
         current += PrintRightXMMOperand(current);
         AppendToBuffer(", %s", NameOfXMMRegister(regop));
       } else if (opcode == 0xD6) {
         AppendToBuffer("movq ");
         current += PrintRightXMMOperand(current);
         AppendToBuffer(", %s", NameOfXMMRegister(regop));
       } else if (opcode == 0x50) {
         AppendToBuffer("movmskpd %s,", NameOfCPURegister(regop));
         current += PrintRightXMMOperand(current);
+      } else if (opcode == 0x76) {
+        AppendToBuffer("pcmpeqd %s,", NameOfXMMRegister(regop));
+        current += PrintRightXMMOperand(current);
       } else {
         const char* mnemonic = "?";
         if (opcode == 0x54) {
           mnemonic = "andpd";
         } else  if (opcode == 0x56) {
           mnemonic = "orpd";
         } else  if (opcode == 0x57) {
           mnemonic = "xorpd";
         } else if (opcode == 0x2E) {
           mnemonic = "ucomisd";
@@ skipping 760 matching lines @@
     for (int i = 6 - static_cast<int>(pc - prev_pc); i >= 0; i--) {
       fprintf(f, "  ");
     }
     fprintf(f, "  %s\n", buffer.start());
   }
 }
 
 }  // namespace disasm
 
 #endif  // V8_TARGET_ARCH_X64