Fix compilation with GCC 5.2

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
@@ skipping 1600 matching lines @@
       __ jmp(&return_label_);
       return;
     } else {
       __ bind(&return_label_);
       __ movq(rsp, rbp);  // Move stack pointer back to frame pointer.
       __ popq(rbp);       // Pop caller's frame pointer.
     }
   }
   size_t pop_size = descriptor->StackParameterCount() * kPointerSize;
   // Might need rcx for scratch if pop_size is too big.
-  DCHECK_EQ(0, descriptor->CalleeSavedRegisters() & rcx.bit());
+  DCHECK_EQ(0u, descriptor->CalleeSavedRegisters() & rcx.bit());
   __ Ret(static_cast<int>(pop_size), rcx);
 }
 
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
   X64OperandConverter g(this, NULL);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {
@@ skipping 180 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8