Improve SeqStringSetChar implementation.

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
diff --git a/src/x64/codegen-x64.cc b/src/x64/codegen-x64.cc
index 6f32f7cf04ea63c348b01dc844f960e81cc4fbe8..2ac56a144cdfdddc185f0f5e452afc38e759a413 100644
--- a/src/x64/codegen-x64.cc
+++ b/src/x64/codegen-x64.cc
@@ -624,46 +624,6 @@ void StringCharLoadGenerator::Generate(MacroAssembler* masm,
 }
 
 
-void SeqStringSetCharGenerator::Generate(MacroAssembler* masm,
-                                         String::Encoding encoding,
-                                         Register string,
-                                         Register index,
-                                         Register value) {
-  if (FLAG_debug_code) {
-    __ Check(masm->CheckSmi(index), "Non-smi index");
-    __ Check(masm->CheckSmi(value), "Non-smi value");
-
-    __ SmiCompare(index, FieldOperand(string, String::kLengthOffset));
-    __ Check(less, "Index is too large");
-
-    __ SmiCompare(index, Smi::FromInt(0));
-    __ Check(greater_equal, "Index is negative");
-
-    __ push(value);
-    __ movq(value, FieldOperand(string, HeapObject::kMapOffset));
-    __ movzxbq(value, FieldOperand(value, Map::kInstanceTypeOffset));
-
-    __ andb(value, Immediate(kStringRepresentationMask | kStringEncodingMask));
-    static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
-    static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
-    __ cmpq(value, Immediate(encoding == String::ONE_BYTE_ENCODING
-                                 ? one_byte_seq_type : two_byte_seq_type));
-    __ Check(equal, "Unexpected string type");
-    __ pop(value);
-  }
-
-  __ SmiToInteger32(value, value);
-  __ SmiToInteger32(index, index);
-  if (encoding == String::ONE_BYTE_ENCODING) {
-    __ movb(FieldOperand(string, index, times_1, SeqString::kHeaderSize),
-            value);
-  } else {
-    __ movw(FieldOperand(string, index, times_2, SeqString::kHeaderSize),
-            value);
-  }
-}
-
-
 void MathExpGenerator::EmitMathExp(MacroAssembler* masm,
                                    XMMRegister input,
                                    XMMRegister result,