[runtime] Implement %_ToLength via ToLengthStub.

src/ia32/code-stubs-ia32.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_IA32
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 3174 matching lines @@
   __ Ret();
   __ bind(&not_oddball);
 
   __ pop(ecx);   // Pop return address.
   __ push(eax);  // Push argument.
   __ push(ecx);  // Push return address.
   __ TailCallRuntime(Runtime::kToNumber, 1, 1);
 }
 
 
+void ToLengthStub::Generate(MacroAssembler* masm) {
+  // The ToLength stub takes on argument in eax.
+  Label not_smi, positive_smi;
+  __ JumpIfNotSmi(eax, &not_smi, Label::kNear);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ test(eax, eax);
+  __ j(greater_equal, &positive_smi, Label::kNear);
+  __ xor_(eax, eax);
+  __ bind(&positive_smi);
+  __ Ret();
+  __ bind(&not_smi);
+
+  __ pop(ecx);   // Pop return address.
+  __ push(eax);  // Push argument.
+  __ push(ecx);  // Push return address.
+  __ TailCallRuntime(Runtime::kToLength, 1, 1);
+}
+
+
 void ToStringStub::Generate(MacroAssembler* masm) {
   // The ToString stub takes one argument in eax.
   Label is_number;
   __ JumpIfSmi(eax, &is_number, Label::kNear);
 
   Label not_string;
   __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, edi);
   // eax: receiver
   // edi: receiver map
   __ j(above_equal, &not_string, Label::kNear);
@@ skipping 2638 matching lines @@
                            Operand(ebp, 7 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32