[Subzero][MIPS32] Implement post lower legalizer 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 443 matching lines @@
   static Type stackSlotType();
   Variable *copyToReg(Operand *Src, RegNumT RegNum = RegNumT());
 
   void unsetIfNonLeafFunc();
 
   // 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 postLowerLegalization();
+
   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);
 
@@ skipping 78 matching lines @@
   void doAddressOptStore() override;
   void randomlyInsertNop(float Probability,
                          RandomNumberGenerator &RNG) override;
   void
   makeRandomRegisterPermutation(llvm::SmallVectorImpl<RegNumT> &Permutation,
                                 const SmallBitVector &ExcludeRegisters,
                                 uint64_t Salt) const override;
 
   OperandMIPS32Mem *formMemoryOperand(Operand *Ptr, Type Ty);
 
+  class PostLoweringLegalizer {
+    PostLoweringLegalizer() = delete;
+    PostLoweringLegalizer(const PostLoweringLegalizer &) = delete;
+    PostLoweringLegalizer &operator=(const PostLoweringLegalizer &) = delete;
+
+  public:
+    explicit PostLoweringLegalizer(TargetMIPS32 *Target)
+        : Target(Target), StackOrFrameReg(Target->getPhysicalRegister(
+                              Target->getFrameOrStackReg())) {}
+
+    /// 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;
   static SmallBitVector TypeToRegisterSet[RCMIPS32_NUM];
   static SmallBitVector TypeToRegisterSetUnfiltered[RCMIPS32_NUM];
   static SmallBitVector RegisterAliases[RegMIPS32::Reg_NUM];
@@ skipping 110 matching lines @@
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace MIPS32
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H