MIPS: [turbofan] Add matching rule to use Nor instruction.

src/compiler/mips/instruction-selector-mips.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 276 matching lines @@
   VisitBinop(this, node, kMipsAnd);
 }
 
 
 void InstructionSelector::VisitWord32Or(Node* node) {
   VisitBinop(this, node, kMipsOr);
 }
 
 
 void InstructionSelector::VisitWord32Xor(Node* node) {
+  Int32BinopMatcher m(node);
+  if (m.left().IsWord32Or() && CanCover(node, m.left().node()) &&
+      m.right().Is(-1)) {
+    Int32BinopMatcher mleft(m.left().node());
+    if (!mleft.right().HasValue()) {
+      MipsOperandGenerator g(this);
+      Emit(kMipsNor, g.DefineAsRegister(node),
+           g.UseRegister(mleft.left().node()),
+           g.UseRegister(mleft.right().node()));
+      return;
+    }
+  }
   VisitBinop(this, node, kMipsXor);
 }
 
 
 void InstructionSelector::VisitWord32Shl(Node* node) {
   VisitRRO(this, kMipsShl, node);
 }
 
 
 void InstructionSelector::VisitWord32Shr(Node* node) {
@@ skipping 859 matching lines @@
   }
   return flags | MachineOperatorBuilder::kFloat64Min |
          MachineOperatorBuilder::kFloat64Max |
          MachineOperatorBuilder::kFloat32Min |
          MachineOperatorBuilder::kFloat32Max;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8