Desugar bitwise negation into XOR and kill all UnaryOp stuff.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 810b16e3489b380c4f2fc92a0c7a957f6ade5f2e..ea9c06cdc4a96621847694aa2b67750b1774b83f 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -1509,7 +1509,11 @@ void LCodeGen::DoBitI(LBitI* instr) {
       __ 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();
@@ -1787,13 +1791,6 @@ void LCodeGen::DoSeqStringSetChar(LSeqStringSetChar* instr) {
 }
 
 
-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);