[turbofan] Fix register constraint for memory barrier.

src/compiler/arm/instruction-selector-arm.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/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 356 matching lines @@
     inputs[input_count++] = g.UseUniqueRegister(base);
     // OutOfLineRecordWrite uses the index in an 'add' instruction as well as
     // for the store itself, so we must check compatibility with both.
     if (g.CanBeImmediate(index, kArmAdd) && g.CanBeImmediate(index, kArmStr)) {
       inputs[input_count++] = g.UseImmediate(index);
       addressing_mode = kMode_Offset_RI;
     } else {
       inputs[input_count++] = g.UseUniqueRegister(index);
       addressing_mode = kMode_Offset_RR;
     }
-    inputs[input_count++] = (write_barrier_kind == kMapWriteBarrier)
-                                ? g.UseRegister(value)
-                                : g.UseUniqueRegister(value);
+    inputs[input_count++] = g.UseUniqueRegister(value);
     RecordWriteMode record_write_mode = RecordWriteMode::kValueIsAny;
     switch (write_barrier_kind) {
       case kNoWriteBarrier:
         UNREACHABLE();
         break;
       case kMapWriteBarrier:
         record_write_mode = RecordWriteMode::kValueIsMap;
         break;
       case kPointerWriteBarrier:
         record_write_mode = RecordWriteMode::kValueIsPointer;
@@ skipping 1343 matching lines @@
              MachineOperatorBuilder::kFloat64RoundTiesAway |
              MachineOperatorBuilder::kFloat32RoundTiesEven |
              MachineOperatorBuilder::kFloat64RoundTiesEven;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8