Improve SeqStringSetChar implementation.

src/x64/lithium-codegen-x64.cc

 // Copyright 2013 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 1648 matching lines @@
     __ movq(arg_reg_1, object);
     __ movq(arg_reg_2, index, RelocInfo::NONE64);
     __ CallCFunction(ExternalReference::get_date_field_function(isolate()), 2);
     __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
     __ bind(&done);
   }
 }
 
 
 void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
-  SeqStringSetCharGenerator::Generate(masm(),
-                                      instr->encoding(),
-                                      ToRegister(instr->string()),
-                                      ToRegister(instr->index()),
-                                      ToRegister(instr->value()));
+  Register string = ToRegister(instr->string());
+  Register index = ToRegister(instr->index());
+  Register value = ToRegister(instr->value());
+  String::Encoding encoding = instr->encoding();
+
+  if (FLAG_debug_code) {
+    __ 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);
+  }
+
+  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 LCodeGen::DoBitNotI(LBitNotI* instr) {
   LOperand* input = instr->value();
   ASSERT(input->Equals(instr->result()));
   __ not_(ToRegister(input));
 }
 
 
@@ skipping 3936 matching lines @@
                                FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64