MIPS: Improve SeqStringSetChar implementation.

src/mips/lithium-codegen-mips.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 1582 matching lines @@
     __ bind(&runtime);
     __ PrepareCallCFunction(2, scratch);
     __ li(a1, Operand(index));
     __ CallCFunction(ExternalReference::get_date_field_function(isolate()), 2);
     __ 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());
+  Register scratch = scratch0();
+  String::Encoding encoding = instr->encoding();
+
+  if (FLAG_debug_code) {
+    __ lw(at, FieldMemOperand(string, HeapObject::kMapOffset));
+    __ lbu(at, FieldMemOperand(at, Map::kInstanceTypeOffset));
+
+    __ And(at, at, Operand(kStringRepresentationMask | kStringEncodingMask));
+    static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
+    static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
+    __ Subu(at, at, Operand(encoding == String::ONE_BYTE_ENCODING
+                                ? one_byte_seq_type : two_byte_seq_type));
+    __ Check(eq, "Unexpected string type", at, Operand(zero_reg));
+  }
+
+  __ Addu(scratch,
+          string,
+          Operand(SeqString::kHeaderSize - kHeapObjectTag));
+  if (encoding == String::ONE_BYTE_ENCODING) {
+    __ Addu(at, scratch, index);
+    __ sb(value, MemOperand(at));
+  } else {
+    __ sll(at, index, 1);
+    __ Addu(at, scratch, at);
+    __ sh(value, MemOperand(at));
+  }
 }
 
 
 void LCodeGen::DoBitNotI(LBitNotI* instr) {
   Register input = ToRegister(instr->value());
   Register result = ToRegister(instr->result());
   __ Nor(result, zero_reg, Operand(input));
 }
 
 
@@ skipping 4055 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal