[runtime] Add %ToString and %_ToString and remove the TO_STRING builtin.

src/mips/code-stubs-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3399 matching lines @@
   __ Branch(&not_oddball, ne, a1, Operand(ODDBALL_TYPE));
   __ Ret(USE_DELAY_SLOT);
   __ lw(v0, FieldMemOperand(a0, Oddball::kToNumberOffset));
   __ bind(&not_oddball);
 
   __ push(a0);  // Push argument.
   __ TailCallRuntime(Runtime::kToNumber, 1, 1);
 }
 
 
+void ToStringStub::Generate(MacroAssembler* masm) {
+  // The ToString stub takes on argument in a0.
+  Label is_number;
+  __ JumpIfSmi(a0, &is_number);
+
+  Label not_string;
+  __ GetObjectType(a0, a1, a1);
+  // a0: receiver
+  // a1: receiver instance type
+  __ Branch(&not_string, ge, a1, Operand(FIRST_NONSTRING_TYPE));
+  __ Ret(USE_DELAY_SLOT);
+  __ mov(v0, a0);
+  __ bind(&not_string);
+
+  Label not_heap_number;
+  __ Branch(&not_heap_number, ne, a1, Operand(HEAP_NUMBER_TYPE));
+  __ bind(&is_number);
+  NumberToStringStub stub(isolate());
+  __ TailCallStub(&stub);
+  __ bind(&not_heap_number);
+
+  Label not_oddball;
+  __ Branch(&not_oddball, ne, a1, Operand(ODDBALL_TYPE));
+  __ Ret(USE_DELAY_SLOT);
+  __ lw(v0, FieldMemOperand(a0, Oddball::kToStringOffset));
+  __ bind(&not_oddball);
+
+  __ push(a0);  // Push argument.
+  __ TailCallRuntime(Runtime::kToString, 1, 1);
+}
+
+
 void StringHelper::GenerateFlatOneByteStringEquals(
     MacroAssembler* masm, Register left, Register right, Register scratch1,
     Register scratch2, Register scratch3) {
   Register length = scratch1;
 
   // Compare lengths.
   Label strings_not_equal, check_zero_length;
   __ lw(length, FieldMemOperand(left, String::kLengthOffset));
   __ lw(scratch2, FieldMemOperand(right, String::kLengthOffset));
   __ Branch(&check_zero_length, eq, length, Operand(scratch2));
@@ skipping 2198 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS