AIX: Fix 'may be used uninitialized' compiler errors

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 399 matching lines @@
   *me = mask_lsb;
   return true;
 }
 #endif
 
 
 // TODO(mbrandy): Absorb rotate-right into rlwinm?
 void InstructionSelector::VisitWord32And(Node* node) {
   PPCOperandGenerator g(this);
   Int32BinopMatcher m(node);
-  int mb;
-  int me;
+  int mb = 0;
+  int me = 0;
   if (m.right().HasValue() && IsContiguousMask32(m.right().Value(), &mb, &me)) {
     int sh = 0;
     Node* left = m.left().node();
     if ((m.left().IsWord32Shr() || m.left().IsWord32Shl()) &&
         CanCover(node, left)) {
       // Try to absorb left/right shift into rlwinm
       Int32BinopMatcher mleft(m.left().node());
       if (mleft.right().IsInRange(0, 31)) {
         left = mleft.left().node();
         sh = mleft.right().Value();
@@ skipping 17 matching lines @@
       this, node, &m, kPPC_And, CanCover(node, m.left().node()),
       CanCover(node, m.right().node()), kInt16Imm_Unsigned);
 }
 
 
 #if V8_TARGET_ARCH_PPC64
 // TODO(mbrandy): Absorb rotate-right into rldic?
 void InstructionSelector::VisitWord64And(Node* node) {
   PPCOperandGenerator g(this);
   Int64BinopMatcher m(node);
-  int mb;
-  int me;
+  int mb = 0;
+  int me = 0;
   if (m.right().HasValue() && IsContiguousMask64(m.right().Value(), &mb, &me)) {
     int sh = 0;
     Node* left = m.left().node();
     if ((m.left().IsWord64Shr() || m.left().IsWord64Shl()) &&
         CanCover(node, left)) {
       // Try to absorb left/right shift into rldic
       Int64BinopMatcher mleft(m.left().node());
       if (mleft.right().IsInRange(0, 63)) {
         left = mleft.left().node();
         sh = mleft.right().Value();
@@ skipping 1105 matching lines @@
   return MachineOperatorBuilder::kFloat64RoundDown |
          MachineOperatorBuilder::kFloat64RoundTruncate |
          MachineOperatorBuilder::kFloat64RoundTiesAway |
          MachineOperatorBuilder::kWord32Popcnt;
   // We omit kWord32ShiftIsSafe as s[rl]w use 0x3f as a mask rather than 0x1f.
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8