MIPS:[turbofan] Use Nor instruction for bit negation instead of xori.

src/compiler/mips64/instruction-selector-mips64.cc

Index: src/compiler/mips64/instruction-selector-mips64.cc
diff --git a/src/compiler/mips64/instruction-selector-mips64.cc b/src/compiler/mips64/instruction-selector-mips64.cc
index 90b3e37221d7388a97eb1060b7946901f2a6ebce..8ed355018085b6650c62ae32523cd4b43fc6cd95 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -359,6 +359,13 @@ void InstructionSelector::VisitWord32Xor(Node* node) {
       return;
     }
   }
+  if (m.right().Is(-1)) {
+    // Use Nor for bit negation and eliminate constant loading for xori.
+    Mips64OperandGenerator g(this);
+    Emit(kMips64Nor, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+         g.TempImmediate(0));
+    return;
+  }
   VisitBinop(this, node, kMips64Xor);
 }
 
@@ -376,6 +383,13 @@ void InstructionSelector::VisitWord64Xor(Node* node) {
       return;
     }
   }
+  if (m.right().Is(-1)) {
+    // Use Nor for bit negation and eliminate constant loading for xori.
+    Mips64OperandGenerator g(this);
+    Emit(kMips64Nor, g.DefineAsRegister(node), g.UseRegister(m.left().node()),
+         g.TempImmediate(0));
+    return;
+  }
   VisitBinop(this, node, kMips64Xor);
 }