[compiler] Drop the CompareNilIC.

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 3986 matching lines @@
                                               NilValue nil) {
   Label materialize_true, materialize_false;
   Label* if_true = NULL;
   Label* if_false = NULL;
   Label* fall_through = NULL;
   context()->PrepareTest(&materialize_true, &materialize_false,
                          &if_true, &if_false, &fall_through);
 
   VisitForAccumulatorValue(sub_expr);
   PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  __ mov(a0, result_register());
   if (expr->op() == Token::EQ_STRICT) {
     Heap::RootListIndex nil_value = nil == kNullValue ?
         Heap::kNullValueRootIndex :
         Heap::kUndefinedValueRootIndex;
     __ LoadRoot(a1, nil_value);
-    Split(eq, a0, Operand(a1), if_true, if_false, fall_through);
+    Split(eq, v0, Operand(a1), if_true, if_false, fall_through);
   } else {
-    Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
-    CallIC(ic, expr->CompareOperationFeedbackId());
-    __ LoadRoot(a1, Heap::kTrueValueRootIndex);
-    Split(eq, v0, Operand(a1), if_true, if_false, fall_through);
+    __ JumpIfSmi(v0, if_false);
+    __ lw(v0, FieldMemOperand(v0, HeapObject::kMapOffset));
+    __ lbu(a1, FieldMemOperand(v0, Map::kBitFieldOffset));
+    __ And(a1, a1, Operand(1 << Map::kIsUndetectable));
+    Split(ne, a1, Operand(zero_reg), if_true, if_false, fall_through);
   }
   context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {
   __ lw(v0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
   context()->Plug(v0);
 }
 
@@ skipping 187 matching lines @@
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS