MIPS: Correctify instanceof and make it optimizable.

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 5100 matching lines @@
   switch (op) {
     case Token::IN:
       VisitForStackValue(expr->right());
       __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION);
       PrepareForBailoutBeforeSplit(expr, false, NULL, NULL);
       __ LoadRoot(t0, Heap::kTrueValueRootIndex);
       Split(eq, v0, Operand(t0), if_true, if_false, fall_through);
       break;
 
     case Token::INSTANCEOF: {
-      VisitForStackValue(expr->right());
-      InstanceofStub stub(isolate(), InstanceofStub::kNoFlags);
+      VisitForAccumulatorValue(expr->right());
+      __ mov(a0, result_register());
+      __ pop(a1);
+      InstanceOfStub stub(isolate());
       __ CallStub(&stub);
-      PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-      // The stub returns 0 for true.
-      Split(eq, v0, Operand(zero_reg), if_true, if_false, fall_through);
+      PrepareForBailoutBeforeSplit(expr, false, NULL, NULL);
+      __ LoadRoot(at, Heap::kTrueValueRootIndex);
+      Split(eq, v0, Operand(at), if_true, if_false, fall_through);
       break;
     }
 
     default: {
       VisitForAccumulatorValue(expr->right());
       Condition cc = CompareIC::ComputeCondition(op);
       __ mov(a0, result_register());
       __ pop(a1);
 
       bool inline_smi_code = ShouldInlineSmiCase(op);
@@ skipping 239 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS