[Subzero][MIPS32] Adds prolog instructions for MIPS32

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 373 matching lines @@
     return getPhysicalRegister(RegMIPS32::Reg_ZERO, IceType_i32);
   }
 
   Variable *I32Reg(RegNumT RegNum = RegNumT()) {
     return makeReg(IceType_i32, RegNum);
   }
 
   static Type stackSlotType();
   Variable *copyToReg(Operand *Src, RegNumT RegNum = RegNumT());
 
+  // Iterates over the CFG and determines the maximum outgoing stack arguments
+  // bytes. This information is later used during addProlog() to pre-allocate
+  // the outargs area
+  void findMaxStackOutArgsSize();
+
   void addProlog(CfgNode *Node) override;
   void addEpilog(CfgNode *Node) override;
 
   // Ensure that a 64-bit Variable has been split into 2 32-bit
   // Variables, creating them if necessary.  This is needed for all
   // I64 operations.
   void split64(Variable *Var);
   Operand *loOperand(Operand *Operand);
   Operand *hiOperand(Operand *Operand);
 
+  void finishArgumentLowering(Variable *Arg, Variable *FramePtr,
+                              size_t BasicFrameOffset, size_t *InArgsSizeBytes);
+
   Operand *legalizeUndef(Operand *From, RegNumT RegNum = RegNumT());
 
 protected:
   explicit TargetMIPS32(Cfg *Func);
 
   void postLower() override;
 
   void lowerAlloca(const InstAlloca *Instr) override;
   void lowerArithmetic(const InstArithmetic *Instr) override;
   void lowerInt64Arithmetic(const InstArithmetic *Instr, Variable *Dest,
@@ skipping 29 matching lines @@
                          RandomNumberGenerator &RNG) override;
   void
   makeRandomRegisterPermutation(llvm::SmallVectorImpl<RegNumT> &Permutation,
                                 const SmallBitVector &ExcludeRegisters,
                                 uint64_t Salt) const override;
 
   OperandMIPS32Mem *formMemoryOperand(Operand *Ptr, Type Ty);
 
   bool UsesFramePointer = false;
   bool NeedsStackAlignment = false;
+  bool MaybeLeafFunc = true;
+  bool PrologEmitsFixedAllocas = false;
+  uint32_t MaxOutArgsSizeBytes = 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;
 
 private:
   ENABLE_MAKE_UNIQUE;
 
   class ComputationTracker {
   public:
     ComputationTracker() = default;
     ~ComputationTracker() = default;
 
     void forgetProducers() { KnownComputations.clear(); }
@@ skipping 91 matching lines @@
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H