Cache common constants before lowering.

src/IceTargetLoweringMIPS32.cpp

 //===- subzero/src/IceTargetLoweringMIPS32.cpp - MIPS32 lowering ----------===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 333 matching lines @@
     //
     // If in the future the implementation is changed to lower undef
     // values to uninitialized registers, a FakeDef will be needed:
     //     Context.insert(InstFakeDef::create(Func, Reg));
     // This is in order to ensure that the live range of Reg is not
     // overestimated.  If the constant being lowered is a 64 bit value,
     // then the result should be split and the lo and hi components will
     // need to go in uninitialized registers.
     if (isVectorType(Ty))
       UnimplementedError(Func->getContext()->getFlags());
-    return Ctx->getConstantZero(Ty);
+    return getConstantZero(Ty);
   }
   return From;
 }
 
 Variable *TargetMIPS32::makeReg(Type Type, RegNumT RegNum) {
   // There aren't any 64-bit integer registers for Mips32.
   assert(Type != IceType_i64);
   Variable *Reg = Func->makeVariable(Type);
   if (RegNum.hasValue())
     Reg->setRegNum(RegNum);
@@ skipping 950 matching lines @@
   Str << "\t.set\t"
       << "nomips16\n";
 }
 
 SmallBitVector TargetMIPS32::TypeToRegisterSet[RCMIPS32_NUM];
 SmallBitVector TargetMIPS32::TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
 SmallBitVector TargetMIPS32::RegisterAliases[RegMIPS32::Reg_NUM];
 
 } // end of namespace MIPS32
 } // end of namespace Ice