[turbofan] Fix register constraint for memory barrier.

src/compiler/ppc/instruction-selector-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/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 #include "src/ppc/frames-ppc.h"
 
@@ skipping 234 matching lines @@
 #if V8_TARGET_ARCH_PPC64
         && g.CanBeImmediate(offset, kInt16Imm_4ByteAligned)
 #endif
             ) {
       inputs[input_count++] = g.UseImmediate(offset);
       addressing_mode = kMode_MRI;
     } else {
       inputs[input_count++] = g.UseUniqueRegister(offset);
       addressing_mode = kMode_MRR;
     }
-    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 1565 matching lines @@
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesAway |
          MachineOperatorBuilder::kWord32Popcnt |
          MachineOperatorBuilder::kWord64Popcnt;
   // We omit kWord32ShiftIsSafe as s[rl]w use 0x3f as a mask rather than 0x1f.
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8