Add support for enabling DCHECKs in release mode

src/x87/codegen-x87.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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/codegen.h"
 #include "src/heap/heap.h"
@@ skipping 563 matching lines @@
 CodeAgingHelper::CodeAgingHelper() {
   DCHECK(young_sequence_.length() == kNoCodeAgeSequenceLength);
   CodePatcher patcher(young_sequence_.start(), young_sequence_.length());
   patcher.masm()->push(ebp);
   patcher.masm()->mov(ebp, esp);
   patcher.masm()->push(esi);
   patcher.masm()->push(edi);
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 bool CodeAgingHelper::IsOld(byte* candidate) const {
   return *candidate == kCallOpcode;
 }
 #endif
 
 
 bool Code::IsYoungSequence(Isolate* isolate, byte* sequence) {
   bool result = isolate->code_aging_helper()->IsYoung(sequence);
   DCHECK(result || isolate->code_aging_helper()->IsOld(sequence));
   return result;
@@ skipping 27 matching lines @@
     Code* stub = GetCodeAgeStub(isolate, age, parity);
     CodePatcher patcher(sequence, young_length);
     patcher.masm()->call(stub->instruction_start(), RelocInfo::NONE32);
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X87