VM: Fix identical comparisons with bigints.

runtime/vm/stub_code_ia32.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 2170 matching lines @@
   const Register left = EAX;
   const Register right = EDX;
   const Register temp = ECX;
   __ movl(left, Address(ESP, 2 * kWordSize));
   __ movl(right, Address(ESP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 
-// Called from otpimzied code only. Must preserve any registers that are
-// destroyed.
+// Called from optimized code only.
 // TOS + 0: return address
 // TOS + 1: right argument.
 // TOS + 2: left argument.
 // Returns ZF set.
 void StubCode::GenerateOptimizedIdenticalWithNumberCheckStub(
     Assembler* assembler) {
   const Register left = EAX;
   const Register right = EDX;
   const Register temp = ECX;
-  // Preserve left, right and temp.
-  __ pushl(left);
-  __ pushl(right);
-  __ pushl(temp);
-  __ movl(left, Address(ESP, 5 * kWordSize));
-  __ movl(right, Address(ESP, 4 * kWordSize));
+  __ movl(left, Address(ESP, 2 * kWordSize));
+  __ movl(right, Address(ESP, 1 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
-  __ popl(temp);
-  __ popl(right);
-  __ popl(left);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32