Desugar bitwise negation into XOR and kill all UnaryOp stuff.

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1491 matching lines @@
   }
 
   switch (instr->op()) {
     case Token::BIT_AND:
       __ And(result, left, right);
       break;
     case Token::BIT_OR:
       __ Or(result, left, right);
       break;
     case Token::BIT_XOR:
-      __ Xor(result, left, right);
+      if (right_op->IsConstantOperand() && right.immediate() == int32_t(~0)) {
+        __ Nor(result, zero_reg, left);
+      } else {
+        __ Xor(result, left, right);
+      }
       break;
     default:
       UNREACHABLE();
       break;
   }
 }
 
 
 void LCodeGen::DoShiftI(LShiftI* instr) {
   // Both 'left' and 'right' are "used at start" (see LCodeGen::DoShift), so
@@ skipping 257 matching lines @@
     __ Addu(at, scratch, index);
     __ sb(value, MemOperand(at));
   } else {
     __ sll(at, index, 1);
     __ Addu(at, scratch, at);
     __ sh(value, MemOperand(at));
   }
 }
 
 
-void LCodeGen::DoBitNotI(LBitNotI* instr) {
-  Register input = ToRegister(instr->value());
-  Register result = ToRegister(instr->result());
-  __ Nor(result, zero_reg, Operand(input));
-}
-
-
 void LCodeGen::DoThrow(LThrow* instr) {
   Register input_reg = EmitLoadRegister(instr->value(), at);
   __ push(input_reg);
   CallRuntime(Runtime::kThrow, 1, instr);
 
   if (FLAG_debug_code) {
     __ stop("Unreachable code.");
   }
 }
 
@@ skipping 4048 matching lines @@
   __ Subu(scratch, result, scratch);
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal