Add support for enabling DCHECKs in release mode

src/ppc/codegen-ppc.cc

 // Copyright 2014 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_PPC
 
 #include "src/codegen.h"
 #include "src/macro-assembler.h"
@@ skipping 625 matching lines @@
   PredictableCodeSizeScope scope(patcher->masm(), young_sequence_.length());
   patcher->masm()->PushFixedFrame(r4);
   patcher->masm()->addi(fp, sp,
                         Operand(StandardFrameConstants::kFixedFrameSizeFromFp));
   for (int i = 0; i < kNoCodeAgeSequenceNops; i++) {
     patcher->masm()->nop();
   }
 }
 
 
-#ifdef DEBUG
+#if DCHECK_IS_ON
 bool CodeAgingHelper::IsOld(byte* candidate) const {
   return Assembler::IsNop(Assembler::instr_at(candidate));
 }
 #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 34 matching lines @@
     patcher.masm()->Jump(r3);
     for (int i = 0; i < kCodeAgingSequenceNops; i++) {
       patcher.masm()->nop();
     }
   }
 }
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_PPC