include/llvm/CodeGen/GlobalISel/CombinerHelper.h

   1 //===-- llvm/CodeGen/GlobalISel/CombinerHelper.h --------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===--------------------------------------------------------------------===//
   8 //
   9 /// This contains common combine transformations that may be used in a combine
  10 /// pass,or by the target elsewhere.
  11 /// Targets can pick individual opcode transformations from the helper or use
  12 /// tryCombine which invokes all transformations. All of the transformations
  13 /// return true if the MachineInstruction changed and false otherwise.
  14 //
  15 //===--------------------------------------------------------------------===//
  16
  17 #ifndef LLVM_CODEGEN_GLOBALISEL_COMBINER_HELPER_H
  18 #define LLVM_CODEGEN_GLOBALISEL_COMBINER_HELPER_H
  19
  20 #include "llvm/CodeGen/LowLevelType.h"
  21 #include "llvm/CodeGen/Register.h"
  22
  23 namespace llvm {
  24
  25 class GISelChangeObserver;
  26 class MachineIRBuilder;
  27 class MachineRegisterInfo;
  28 class MachineInstr;
  29 class MachineOperand;
  30 class GISelKnownBits;
  31
  32 struct PreferredTuple {
  33   LLT Ty;                // The result type of the extend.
  34   unsigned ExtendOpcode; // G_ANYEXT/G_SEXT/G_ZEXT
  35   MachineInstr *MI;
  36 };
  37
  38 class CombinerHelper {
  39 protected:
  40   MachineIRBuilder &Builder;
  41   MachineRegisterInfo &MRI;
  42   GISelChangeObserver &Observer;
  43   GISelKnownBits *KB;
  44
  45 public:
  46   CombinerHelper(GISelChangeObserver &Observer, MachineIRBuilder &B,
  47                  GISelKnownBits *KB = nullptr);
  48
  49   /// MachineRegisterInfo::replaceRegWith() and inform the observer of the changes
  50   void replaceRegWith(MachineRegisterInfo &MRI, Register FromReg, Register ToReg) const;
  51
  52   /// Replace a single register operand with a new register and inform the
  53   /// observer of the changes.
  54   void replaceRegOpWith(MachineRegisterInfo &MRI, MachineOperand &FromRegOp,
  55                         Register ToReg) const;
  56
  57   /// If \p MI is COPY, try to combine it.
  58   /// Returns true if MI changed.
  59   bool tryCombineCopy(MachineInstr &MI);
  60   bool matchCombineCopy(MachineInstr &MI);
  61   void applyCombineCopy(MachineInstr &MI);
  62
  63   /// If \p MI is extend that consumes the result of a load, try to combine it.
  64   /// Returns true if MI changed.
  65   bool tryCombineExtendingLoads(MachineInstr &MI);
  66   bool matchCombineExtendingLoads(MachineInstr &MI, PreferredTuple &MatchInfo);
  67   void applyCombineExtendingLoads(MachineInstr &MI, PreferredTuple &MatchInfo);
  68
  69   bool matchCombineBr(MachineInstr &MI);
  70   bool tryCombineBr(MachineInstr &MI);
  71
  72   /// Optimize memcpy intrinsics et al, e.g. constant len calls.
  73   /// /p MaxLen if non-zero specifies the max length of a mem libcall to inline.
  74   bool tryCombineMemCpyFamily(MachineInstr &MI, unsigned MaxLen = 0);
  75
  76   /// Try to transform \p MI by using all of the above
  77   /// combine functions. Returns true if changed.
  78   bool tryCombine(MachineInstr &MI);
  79
  80 private:
  81   // Memcpy family optimization helpers.
  82   bool optimizeMemcpy(MachineInstr &MI, Register Dst, Register Src,
  83                       unsigned KnownLen, unsigned DstAlign, unsigned SrcAlign,
  84                       bool IsVolatile);
  85   bool optimizeMemmove(MachineInstr &MI, Register Dst, Register Src,
  86                       unsigned KnownLen, unsigned DstAlign, unsigned SrcAlign,
  87                       bool IsVolatile);
  88   bool optimizeMemset(MachineInstr &MI, Register Dst, Register Val,
  89                       unsigned KnownLen, unsigned DstAlign, bool IsVolatile);
  90 };
  91 } // namespace llvm
  92
  93 #endif