PPC64: [turbofan] Word32 loads should be unsigned.

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 172 matching lines @@
     case MachineRepresentation::kWord8:
       opcode = load_rep.IsSigned() ? kPPC_LoadWordS8 : kPPC_LoadWordU8;
       break;
     case MachineRepresentation::kWord16:
       opcode = load_rep.IsSigned() ? kPPC_LoadWordS16 : kPPC_LoadWordU16;
       break;
 #if !V8_TARGET_ARCH_PPC64
     case MachineRepresentation::kTagged:  // Fall through.
 #endif
     case MachineRepresentation::kWord32:
-      opcode = kPPC_LoadWordS32;
-#if V8_TARGET_ARCH_PPC64
-      // TODO(mbrandy): this applies to signed loads only (lwa)
-      mode = kInt16Imm_4ByteAligned;
-#endif
+      opcode = kPPC_LoadWordU32;
       break;
 #if V8_TARGET_ARCH_PPC64
     case MachineRepresentation::kTagged:  // Fall through.
     case MachineRepresentation::kWord64:
       opcode = kPPC_LoadWord64;
       mode = kInt16Imm_4ByteAligned;
       break;
 #else
     case MachineRepresentation::kWord64:  // Fall through.
 #endif
@@ skipping 1748 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