Improve implementation of HSeqStringSetChar.

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 1540 matching lines @@
         data++;
         if (is_byte) {
           AppendToBuffer("movb ");
           data += PrintRightByteOperand(data);
           int32_t imm = *data;
           AppendToBuffer(",0x%x", imm);
           data++;
         } else {
           AppendToBuffer("mov%c ", operand_size_code());
           data += PrintRightOperand(data);
-          int32_t imm = *reinterpret_cast<int32_t*>(data);
-          AppendToBuffer(",0x%x", imm);
-          data += 4;
+          if (operand_size() == OPERAND_WORD_SIZE) {
+            int16_t imm = *reinterpret_cast<int16_t*>(data);
+            AppendToBuffer(",0x%x", imm);
+            data += 2;
+          } else {
+            int32_t imm = *reinterpret_cast<int32_t*>(data);
+            AppendToBuffer(",0x%x", imm);
+            data += 4;
+          }
         }
       }
         break;
 
       case 0x80: {
         data++;
         AppendToBuffer("cmpb ");
         data += PrintRightByteOperand(data);
         int32_t imm = *data;
         AppendToBuffer(",0x%x", imm);
@@ skipping 318 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