Improve implementation of HSeqStringSetChar.

src/x64/lithium-x64.cc

 // Copyright 2012 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 1739 matching lines @@
 
 
 LInstruction* LChunkBuilder::DoDateField(HDateField* instr) {
   LOperand* object = UseFixed(instr->value(), rax);
   LDateField* result = new(zone()) LDateField(object, instr->index());
   return MarkAsCall(DefineFixed(result, rax), instr, CAN_DEOPTIMIZE_EAGERLY);
 }
 
 
 LInstruction* LChunkBuilder::DoSeqStringSetChar(HSeqStringSetChar* instr) {
-  LOperand* string = UseRegister(instr->string());
-  LOperand* index = UseRegister(instr->index());
-  ASSERT(rcx.is_byte_register());
-  LOperand* value = UseFixed(instr->value(), rcx);
-  LSeqStringSetChar* result =
-      new(zone()) LSeqStringSetChar(instr->encoding(), string, index, value);
-  return DefineSameAsFirst(result);
+  LOperand* string = UseRegisterAtStart(instr->string());
+  LOperand* index = UseRegisterOrConstantAtStart(instr->index());
+  LOperand* value = UseRegisterOrConstantAtStart(instr->value());
+  return new(zone()) LSeqStringSetChar(string, index, value);
 }
 
 
 LInstruction* LChunkBuilder::DoBoundsCheck(HBoundsCheck* instr) {
   LOperand* value = UseRegisterOrConstantAtStart(instr->index());
   LOperand* length = Use(instr->length());
   return AssignEnvironment(new(zone()) LBoundsCheck(value, length));
 }
 
 
@@ skipping 768 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64