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

src/IceInstMIPS32.h

 //===- subzero/src/IceInstMIPS32.h - MIPS32 machine instrs --*- C++ -*-----===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 1036 matching lines @@
     } else {
       getSrc(0)->dump(Func);
       Str << ",";
       emitRelocOp(Str, Reloc);
       Str << "(";
       getSrc(1)->dump(Func);
       Str << ")";
     }
   }
 
+  uint32_t getImmediateValue() const { return Imm; }
+
   static bool classof(const Inst *Inst) { return isClassof(Inst, K); }
 
 private:
   InstMIPS32Imm16(Cfg *Func, Variable *Dest, Operand *Source, uint32_t Imm,
                   RelocOp Reloc = RO_No)
       : InstMIPS32(Func, K, 1, Dest), Reloc(Reloc), Imm(Imm) {
     addSource(Source);
   }
 
   InstMIPS32Imm16(Cfg *Func, Variable *Dest, uint32_t Imm,
@@ skipping 284 matching lines @@
 template <> void InstMIPS32Trunc_l_s::emitIAS(const Cfg *Func) const;
 template <> void InstMIPS32Trunc_w_d::emitIAS(const Cfg *Func) const;
 template <> void InstMIPS32Trunc_w_s::emitIAS(const Cfg *Func) const;
 template <> void InstMIPS32Xor::emitIAS(const Cfg *Func) const;
 template <> void InstMIPS32Xori::emitIAS(const Cfg *Func) const;
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEINSTMIPS32_H