[runtime] Implement %_ToLength via ToLengthStub.

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 3296 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 ToLengthStub::Generate(MacroAssembler* masm) {
+  // The ToLength stub takes on argument in a0.
+  Label not_smi, positive_smi;
+  __ JumpIfNotSmi(a0, &not_smi);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Branch(&positive_smi, ge, a0, Operand(zero_reg));
+  __ mov(a0, zero_reg);
+  __ bind(&positive_smi);
+  __ Ret(USE_DELAY_SLOT);
+  __ mov(v0, a0);
+  __ bind(&not_smi);
+
+  __ push(a0);  // Push argument.
+  __ TailCallRuntime(Runtime::kToLength, 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));
@@ skipping 2415 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS