[stubs] replaced ToString MacroAssembler Stub with CodeStubAssembler builtin

src/s390/code-stubs-s390.cc

 // Copyright 2014 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_S390
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 2413 matching lines @@
   // r5: from index (untagged)
   __ SmiTag(r5, r5);
   StringCharAtGenerator generator(r2, r5, r4, r2, &runtime, &runtime, &runtime,
                                   RECEIVER_IS_STRING);
   generator.GenerateFast(masm);
   __ Drop(3);
   __ Ret();
   generator.SkipSlow(masm, &runtime);
 }
 
-void ToStringStub::Generate(MacroAssembler* masm) {
-  // The ToString stub takes one argument in r2.
-  Label done;
-  Label is_number;
-  __ JumpIfSmi(r2, &is_number);
-
-  __ CompareObjectType(r2, r3, r3, FIRST_NONSTRING_TYPE);
-  // r2: receiver
-  // r3: receiver instance type
-  __ blt(&done);
-
-  Label not_heap_number;
-  __ CmpP(r3, Operand(HEAP_NUMBER_TYPE));
-  __ bne(&not_heap_number);
-  __ bind(&is_number);
-  NumberToStringStub stub(isolate());
-  __ TailCallStub(&stub);
-  __ bind(&not_heap_number);
-
-  Label not_oddball;
-  __ CmpP(r3, Operand(ODDBALL_TYPE));
-  __ bne(&not_oddball);
-  __ LoadP(r2, FieldMemOperand(r2, Oddball::kToStringOffset));
-  __ Ret();
-  __ bind(&not_oddball);
-
-  __ push(r2);  // Push argument.
-  __ TailCallRuntime(Runtime::kToString);
-
-  __ bind(&done);
-  __ Ret();
-}
-
 void StringHelper::GenerateFlatOneByteStringEquals(MacroAssembler* masm,
                                                    Register left,
                                                    Register right,
                                                    Register scratch1,
                                                    Register scratch2) {
   Register length = scratch1;
 
   // Compare lengths.
   Label strings_not_equal, check_zero_length;
   __ LoadP(length, FieldMemOperand(left, String::kLengthOffset));
@@ skipping 2878 matching lines @@
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref,
                            kStackUnwindSpace, NULL, return_value_operand, NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_S390