[Subzero][MIPS32] Account for variable alloca alignment bytes in addProlog

src/IceTargetLoweringMIPS32.h

 //===- subzero/src/IceTargetLoweringMIPS32.h - MIPS32 lowering ---*- C++-*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 716 matching lines @@
 
   public:
     explicit PostLoweringLegalizer(TargetMIPS32 *Target)
         : Target(Target), StackOrFrameReg(Target->getPhysicalRegister(
                               Target->getFrameOrStackReg())) {}
 
     /// Legalizes Mem. if Mem.Base is a rematerializable variable,
     /// Mem.Offset is fixed up.
     OperandMIPS32Mem *legalizeMemOperand(OperandMIPS32Mem *Mem);
 
+    /// Legalizes Immediate if larger value overflows range of 16 bits
+    Variable *legalizeImmediate(int32_t Imm);
+
     /// Legalizes Mov if its Source (or Destination) is a spilled Variable, or
     /// if its Source is a Rematerializable variable (this form is used in lieu
     /// of lea, which is not available in MIPS.)
     ///
     /// Moves to memory become store instructions, and moves from memory, loads.
     void legalizeMov(InstMIPS32Mov *Mov);
 
   private:
     /// Creates a new Base register centered around [Base, +/- Offset].
     Variable *newBaseRegister(Variable *Base, int32_t Offset,
                               RegNumT ScratchRegNum);
 
     TargetMIPS32 *const Target;
     Variable *const StackOrFrameReg;
   };
 
   bool UsesFramePointer = false;
   bool NeedsStackAlignment = false;
   bool MaybeLeafFunc = true;
   bool PrologEmitsFixedAllocas = false;
   bool VariableAllocaUsed = false;
   uint32_t MaxOutArgsSizeBytes = 0;
   uint32_t TotalStackSizeBytes = 0;
   uint32_t CurrentAllocaOffset = 0;
+  uint32_t VariableAllocaAlignBytes = 0;
   static SmallBitVector TypeToRegisterSet[RCMIPS32_NUM];
   static SmallBitVector TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
   static SmallBitVector RegisterAliases[RegMIPS32::Reg_NUM];
   SmallBitVector RegsUsed;
   VarList PhysicalRegisters[IceType_NUM];
   VarList PreservedGPRs;
   static constexpr uint32_t CHAR_BITS = 8;
   static constexpr uint32_t INT32_BITS = 32;
   size_t SpillAreaSizeBytes = 0;
   size_t FixedAllocaSizeBytes = 0;
@@ skipping 106 matching lines @@
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H