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

src/arm64/code-stubs-arm64.cc

 // Copyright 2013 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_ARM64
 
 #include "src/arm64/frames-arm64.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3981 matching lines @@
   __ B(ne, &not_oddball);
   __ Ldr(x0, FieldMemOperand(x0, Oddball::kToNumberOffset));
   __ Ret();
   __ Bind(&not_oddball);
 
   __ Push(x0);  // Push argument.
   __ TailCallRuntime(Runtime::kToNumber, 1, 1);
 }
 
 
+void ToStringStub::Generate(MacroAssembler* masm) {
+  // The ToString stub takes one argument in x0.
+  Label is_number;
+  __ JumpIfSmi(x0, &is_number);
+
+  Label not_string;
+  __ JumpIfObjectType(x0, x1, x1, FIRST_NONSTRING_TYPE, &not_string, hs);
+  // x0: receiver
+  // x1: receiver instance type
+  __ Ret();
+  __ Bind(&not_string);
+
+  Label not_heap_number;
+  __ Cmp(x1, HEAP_NUMBER_TYPE);
+  __ B(ne, &not_heap_number);
+  __ Bind(&is_number);
+  NumberToStringStub stub(isolate());
+  __ TailCallStub(&stub);
+  __ Bind(&not_heap_number);
+
+  Label not_oddball;
+  __ Cmp(x1, ODDBALL_TYPE);
+  __ B(ne, &not_oddball);
+  __ Ldr(x0, FieldMemOperand(x0, Oddball::kToStringOffset));
+  __ Ret();
+  __ Bind(&not_oddball);
+
+  __ Push(x0);  // Push argument.
+  __ TailCallRuntime(Runtime::kToString, 1, 1);
+}
+
+
 void StringHelper::GenerateFlatOneByteStringEquals(
     MacroAssembler* masm, Register left, Register right, Register scratch1,
     Register scratch2, Register scratch3) {
   DCHECK(!AreAliased(left, right, scratch1, scratch2, scratch3));
   Register result = x0;
   Register left_length = scratch1;
   Register right_length = scratch2;
 
   // Compare lengths. If lengths differ, strings can't be equal. Lengths are
   // smis, and don't need to be untagged.
@@ skipping 1899 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64