Add support for enabling DCHECKs in release mode

src/x64/assembler-x64.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_X64
 
 #include "src/base/bits.h"
 #include "src/macro-assembler.h"
@@ skipping 36 matching lines @@
 
 // Patch the code at the current PC with a call to the target address.
 // Additional guard int3 instructions can be added if required.
 void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
   int code_size = Assembler::kCallSequenceLength + guard_bytes;
 
   // Create a code patcher.
   CodePatcher patcher(pc_, code_size);
 
   // Add a label for checking the size of the code used for returning.
-#ifdef DEBUG
+#if DCHECK_IS_ON
   Label check_codesize;
   patcher.masm()->bind(&check_codesize);
 #endif
 
   // Patch the code.
   patcher.masm()->movp(kScratchRegister, reinterpret_cast<void*>(target),
                        Assembler::RelocInfoNone());
   patcher.masm()->call(kScratchRegister);
 
   // Check that the size of the code generated is as expected.
@@ skipping 3282 matching lines @@
 
 
 bool RelocInfo::IsInConstantPool() {
   return false;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64