MIPS: Fix deoptimization failure in WordCompare

src/full-codegen/mips/full-codegen-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
 
 // Note on Mips implementation:
 //
 // The result_register() for mips is the 'v0' register, which is defined
 // by the ABI to contain function return values. However, the first
@@ skipping 718 matching lines @@
   // Only prepare for bailouts before splits if we're in a test
   // context. Otherwise, we let the Visit function deal with the
   // preparation to avoid preparing with the same AST id twice.
   if (!context()->IsTest()) return;
 
   Label skip;
   if (should_normalize) __ Branch(&skip);
   PrepareForBailout(expr, BailoutState::TOS_REGISTER);
   if (should_normalize) {
     __ LoadRoot(t0, Heap::kTrueValueRootIndex);
-    Split(eq, a0, Operand(t0), if_true, if_false, NULL);
+    Split(eq, v0, Operand(t0), if_true, if_false, NULL);
     __ bind(&skip);
   }
 }
 
 
 void FullCodeGenerator::EmitDebugCheckDeclarationContext(Variable* variable) {
   // The variable in the declaration always resides in the current function
   // context.
   DCHECK_EQ(0, scope()->ContextChainLength(variable->scope()));
   if (FLAG_debug_code) {
@@ skipping 3037 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OnStackReplacement()->entry()));
   return ON_STACK_REPLACEMENT;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS