[Turbofan] Add USE for local used only by DCHECK.

src/compiler/register-allocator.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/base/adapters.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/register-allocator.h"
 #include "src/string-stream.h"
 
 namespace v8 {
@@ skipping 1918 matching lines @@
     case MachineRepresentation::kSimd128:
       num_regs = config()->num_simd128_registers();
       live_ranges = &data()->fixed_simd128_live_ranges();
       break;
     default:
       UNREACHABLE();
       break;
   }
 
   DCHECK(index < num_regs);
+  USE(num_regs);
   TopLevelLiveRange* result = (*live_ranges)[index];
   if (result == nullptr) {
     result = data()->NewLiveRange(FixedFPLiveRangeID(index, rep), rep);
     DCHECK(result->IsFixed());
     result->set_assigned_register(index);
     data()->MarkAllocated(rep, index);
     (*live_ranges)[index] = result;
   }
   return result;
 }
@@ skipping 2001 matching lines @@
         }
       }
     }
   }
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8