VM: Fix identical comparisons with bigints.

runtime/vm/stub_code_mips.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_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 2382 matching lines @@
   __ sw(RA, Address(SP, 0 * kWordSize));  // Return address.
   __ CallRuntime(kSingleStepHandlerRuntimeEntry, 0);
   __ lw(RA, Address(SP, 0 * kWordSize));
   __ addiu(SP, SP, Immediate(1 * kWordSize));
   __ Bind(&not_stepping);
 
   const Register temp1 = T2;
   const Register temp2 = T3;
   const Register left = T1;
   const Register right = T0;
-  // Preserve left, right.
   __ lw(left, Address(SP, 1 * kWordSize));
   __ lw(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp1, temp2);
   __ Ret();
 }
 
 
-// Called from otpimzied code only. Must preserve any registers that are
-// destroyed.
+// Called from optimized code only.
 // SP + 4: left operand.
 // SP + 0: right operand.
 // Returns: CMPRES1 is zero if equal, non-zero otherwise.
 void StubCode::GenerateOptimizedIdenticalWithNumberCheckStub(
     Assembler* assembler) {
   const Register temp1 = T2;
   const Register temp2 = T3;
   const Register left = T1;
   const Register right = T0;
-  // Preserve left, right.
-  __ addiu(SP, SP, Immediate(-4 * kWordSize));
-  __ sw(temp1, Address(SP, 3 * kWordSize));
-  __ sw(temp2, Address(SP, 2 * kWordSize));
-  __ sw(left, Address(SP, 1 * kWordSize));
-  __ sw(right, Address(SP, 0 * kWordSize));
-  __ lw(left, Address(SP, 5 * kWordSize));
-  __ lw(right, Address(SP, 4 * kWordSize));
+  __ lw(left, Address(SP, 1 * kWordSize));
+  __ lw(right, Address(SP, 0 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp1, temp2);
-  __ lw(right, Address(SP, 0 * kWordSize));
-  __ lw(left, Address(SP, 1 * kWordSize));
-  __ lw(temp2, Address(SP, 2 * kWordSize));
-  __ lw(temp1, Address(SP, 3 * kWordSize));
   __ Ret();
-  __ delay_slot()->addiu(SP, SP, Immediate(4 * kWordSize));
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS