Improve implementation of HSeqStringSetChar.

src/ia32/lithium-ia32.h

Index: src/ia32/lithium-ia32.h
diff --git a/src/ia32/lithium-ia32.h b/src/ia32/lithium-ia32.h
index 752fdd4f6afb7222e0f78503952c30879737fb97..23acd27e23b01846ba8ad9cc23077f0e0aec4d00 100644
--- a/src/ia32/lithium-ia32.h
+++ b/src/ia32/lithium-ia32.h
@@ -1339,25 +1339,20 @@ class LDateField V8_FINAL : public LTemplateInstruction<1, 1, 1> {
 
 class LSeqStringSetChar V8_FINAL : public LTemplateInstruction<1, 3, 0> {
  public:
-  LSeqStringSetChar(String::Encoding encoding,
-                    LOperand* string,
+  LSeqStringSetChar(LOperand* string,
                     LOperand* index,
-                    LOperand* value) : encoding_(encoding) {
+                    LOperand* value) {
     inputs_[0] = string;
     inputs_[1] = index;
     inputs_[2] = value;
   }
 
-  String::Encoding encoding() { return encoding_; }
   LOperand* string() { return inputs_[0]; }
   LOperand* index() { return inputs_[1]; }
   LOperand* value() { return inputs_[2]; }
 
   DECLARE_CONCRETE_INSTRUCTION(SeqStringSetChar, "seq-string-set-char")
   DECLARE_HYDROGEN_ACCESSOR(SeqStringSetChar)
-
- private:
-  String::Encoding encoding_;
 };
 
 
@@ -2832,6 +2827,10 @@ class LChunkBuilder V8_FINAL BASE_EMBEDDED {
   MUST_USE_RESULT LOperand* UseOrConstant(HValue* value);
   MUST_USE_RESULT LOperand* UseOrConstantAtStart(HValue* value);
 
+  // An input operand in a fixed register or a constant operand.
+  MUST_USE_RESULT LOperand* UseFixedOrConstant(HValue* value,
+                                               Register fixed_register);
+
   // An input operand in a register or a constant operand.
   MUST_USE_RESULT LOperand* UseRegisterOrConstant(HValue* value);
   MUST_USE_RESULT LOperand* UseRegisterOrConstantAtStart(HValue* value);