1 //===- llvm/CodeGen/GlobalISel/CSEInfo.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 /// Provides analysis for continuously CSEing during GISel passes. 10 // 11 //===----------------------------------------------------------------------===// 12 #ifndef LLVM_CODEGEN_GLOBALISEL_CSEINFO_H 13 #define LLVM_CODEGEN_GLOBALISEL_CSEINFO_H 14 15 #include "llvm/ADT/FoldingSet.h" 16 #include "llvm/CodeGen/CSEConfigBase.h" 17 #include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h" 18 #include "llvm/CodeGen/GlobalISel/GISelWorkList.h" 19 #include "llvm/CodeGen/GlobalISel/Utils.h" 20 #include "llvm/CodeGen/MachineBasicBlock.h" 21 #include "llvm/CodeGen/MachineFunctionPass.h" 22 #include "llvm/IR/PassManager.h" 23 #include "llvm/Pass.h" 24 #include "llvm/Support/Allocator.h" 25 26 namespace llvm { 27 28 /// A class that wraps MachineInstrs and derives from FoldingSetNode in order to 29 /// be uniqued in a CSEMap. The tradeoff here is extra memory allocations for 30 /// UniqueMachineInstr vs making MachineInstr bigger. 31 class UniqueMachineInstr : public FoldingSetNode { 32 friend class GISelCSEInfo; 33 const MachineInstr *MI; UniqueMachineInstr(const MachineInstr * MI)34 explicit UniqueMachineInstr(const MachineInstr *MI) : MI(MI) {} 35 36 public: 37 void Profile(FoldingSetNodeID &ID); 38 }; 39 40 // A CSE config for fully optimized builds. 41 class CSEConfigFull : public CSEConfigBase { 42 public: 43 virtual ~CSEConfigFull() = default; 44 virtual bool shouldCSEOpc(unsigned Opc) override; 45 }; 46 47 // Commonly used for O0 config. 48 class CSEConfigConstantOnly : public CSEConfigBase { 49 public: 50 virtual ~CSEConfigConstantOnly() = default; 51 virtual bool shouldCSEOpc(unsigned Opc) override; 52 }; 53 54 // Returns the standard expected CSEConfig for the given optimization level. 55 // We have this logic here so targets can make use of it from their derived 56 // TargetPassConfig, but can't put this logic into TargetPassConfig directly 57 // because the CodeGen library can't depend on GlobalISel. 58 std::unique_ptr<CSEConfigBase> 59 getStandardCSEConfigForOpt(CodeGenOpt::Level Level); 60 61 /// The CSE Analysis object. 62 /// This installs itself as a delegate to the MachineFunction to track 63 /// new instructions as well as deletions. It however will not be able to 64 /// track instruction mutations. In such cases, recordNewInstruction should be 65 /// called (for eg inside MachineIRBuilder::recordInsertion). 66 /// Also because of how just the instruction can be inserted without adding any 67 /// operands to the instruction, instructions are uniqued and inserted lazily. 68 /// CSEInfo should assert when trying to enter an incomplete instruction into 69 /// the CSEMap. There is Opcode level granularity on which instructions can be 70 /// CSE'd and for now, only Generic instructions are CSEable. 71 class GISelCSEInfo : public GISelChangeObserver { 72 // Make it accessible only to CSEMIRBuilder. 73 friend class CSEMIRBuilder; 74 75 BumpPtrAllocator UniqueInstrAllocator; 76 FoldingSet<UniqueMachineInstr> CSEMap; 77 MachineRegisterInfo *MRI = nullptr; 78 MachineFunction *MF = nullptr; 79 std::unique_ptr<CSEConfigBase> CSEOpt; 80 /// Keep a cache of UniqueInstrs for each MachineInstr. In GISel, 81 /// often instructions are mutated (while their ID has completely changed). 82 /// Whenever mutation happens, invalidate the UniqueMachineInstr for the 83 /// MachineInstr 84 DenseMap<const MachineInstr *, UniqueMachineInstr *> InstrMapping; 85 86 /// Store instructions that are not fully formed in TemporaryInsts. 87 /// Also because CSE insertion happens lazily, we can remove insts from this 88 /// list and avoid inserting and then removing from the CSEMap. 89 GISelWorkList<8> TemporaryInsts; 90 91 // Only used in asserts. 92 DenseMap<unsigned, unsigned> OpcodeHitTable; 93 94 bool isUniqueMachineInstValid(const UniqueMachineInstr &UMI) const; 95 96 void invalidateUniqueMachineInstr(UniqueMachineInstr *UMI); 97 98 UniqueMachineInstr *getNodeIfExists(FoldingSetNodeID &ID, 99 MachineBasicBlock *MBB, void *&InsertPos); 100 101 /// Allocate and construct a new UniqueMachineInstr for MI and return. 102 UniqueMachineInstr *getUniqueInstrForMI(const MachineInstr *MI); 103 104 void insertNode(UniqueMachineInstr *UMI, void *InsertPos = nullptr); 105 106 /// Get the MachineInstr(Unique) if it exists already in the CSEMap and the 107 /// same MachineBasicBlock. 108 MachineInstr *getMachineInstrIfExists(FoldingSetNodeID &ID, 109 MachineBasicBlock *MBB, 110 void *&InsertPos); 111 112 /// Use this method to allocate a new UniqueMachineInstr for MI and insert it 113 /// into the CSEMap. MI should return true for shouldCSE(MI->getOpcode()) 114 void insertInstr(MachineInstr *MI, void *InsertPos = nullptr); 115 116 public: 117 GISelCSEInfo() = default; 118 119 virtual ~GISelCSEInfo(); 120 121 void setMF(MachineFunction &MF); 122 123 /// Records a newly created inst in a list and lazily insert it to the CSEMap. 124 /// Sometimes, this method might be called with a partially constructed 125 /// MachineInstr, 126 // (right after BuildMI without adding any operands) - and in such cases, 127 // defer the hashing of the instruction to a later stage. 128 void recordNewInstruction(MachineInstr *MI); 129 130 /// Use this callback to inform CSE about a newly fully created instruction. 131 void handleRecordedInst(MachineInstr *MI); 132 133 /// Use this callback to insert all the recorded instructions. At this point, 134 /// all of these insts need to be fully constructed and should not be missing 135 /// any operands. 136 void handleRecordedInsts(); 137 138 /// Remove this inst from the CSE map. If this inst has not been inserted yet, 139 /// it will be removed from the Tempinsts list if it exists. 140 void handleRemoveInst(MachineInstr *MI); 141 142 void releaseMemory(); 143 setCSEConfig(std::unique_ptr<CSEConfigBase> Opt)144 void setCSEConfig(std::unique_ptr<CSEConfigBase> Opt) { 145 CSEOpt = std::move(Opt); 146 } 147 148 bool shouldCSE(unsigned Opc) const; 149 150 void analyze(MachineFunction &MF); 151 152 void countOpcodeHit(unsigned Opc); 153 154 void print(); 155 156 // Observer API 157 void erasingInstr(MachineInstr &MI) override; 158 void createdInstr(MachineInstr &MI) override; 159 void changingInstr(MachineInstr &MI) override; 160 void changedInstr(MachineInstr &MI) override; 161 }; 162 163 class TargetRegisterClass; 164 class RegisterBank; 165 166 // Simple builder class to easily profile properties about MIs. 167 class GISelInstProfileBuilder { 168 FoldingSetNodeID &ID; 169 const MachineRegisterInfo &MRI; 170 171 public: GISelInstProfileBuilder(FoldingSetNodeID & ID,const MachineRegisterInfo & MRI)172 GISelInstProfileBuilder(FoldingSetNodeID &ID, const MachineRegisterInfo &MRI) 173 : ID(ID), MRI(MRI) {} 174 // Profiling methods. 175 const GISelInstProfileBuilder &addNodeIDOpcode(unsigned Opc) const; 176 const GISelInstProfileBuilder &addNodeIDRegType(const LLT &Ty) const; 177 const GISelInstProfileBuilder &addNodeIDRegType(const unsigned) const; 178 179 const GISelInstProfileBuilder & 180 addNodeIDRegType(const TargetRegisterClass *RC) const; 181 const GISelInstProfileBuilder &addNodeIDRegType(const RegisterBank *RB) const; 182 183 const GISelInstProfileBuilder &addNodeIDRegNum(unsigned Reg) const; 184 185 const GISelInstProfileBuilder &addNodeIDImmediate(int64_t Imm) const; 186 const GISelInstProfileBuilder & 187 addNodeIDMBB(const MachineBasicBlock *MBB) const; 188 189 const GISelInstProfileBuilder & 190 addNodeIDMachineOperand(const MachineOperand &MO) const; 191 192 const GISelInstProfileBuilder &addNodeIDFlag(unsigned Flag) const; 193 const GISelInstProfileBuilder &addNodeID(const MachineInstr *MI) const; 194 }; 195 196 /// Simple wrapper that does the following. 197 /// 1) Lazily evaluate the MachineFunction to compute CSEable instructions. 198 /// 2) Allows configuration of which instructions are CSEd through CSEConfig 199 /// object. Provides a method called get which takes a CSEConfig object. 200 class GISelCSEAnalysisWrapper { 201 GISelCSEInfo Info; 202 MachineFunction *MF = nullptr; 203 bool AlreadyComputed = false; 204 205 public: 206 /// Takes a CSEConfigBase object that defines what opcodes get CSEd. 207 /// If CSEConfig is already set, and the CSE Analysis has been preserved, 208 /// it will not use the new CSEOpt(use Recompute to force using the new 209 /// CSEOpt). 210 GISelCSEInfo &get(std::unique_ptr<CSEConfigBase> CSEOpt, 211 bool ReCompute = false); setMF(MachineFunction & MFunc)212 void setMF(MachineFunction &MFunc) { MF = &MFunc; } setComputed(bool Computed)213 void setComputed(bool Computed) { AlreadyComputed = Computed; } releaseMemory()214 void releaseMemory() { Info.releaseMemory(); } 215 }; 216 217 /// The actual analysis pass wrapper. 218 class GISelCSEAnalysisWrapperPass : public MachineFunctionPass { 219 GISelCSEAnalysisWrapper Wrapper; 220 221 public: 222 static char ID; 223 GISelCSEAnalysisWrapperPass(); 224 225 void getAnalysisUsage(AnalysisUsage &AU) const override; 226 getCSEWrapper()227 const GISelCSEAnalysisWrapper &getCSEWrapper() const { return Wrapper; } getCSEWrapper()228 GISelCSEAnalysisWrapper &getCSEWrapper() { return Wrapper; } 229 230 bool runOnMachineFunction(MachineFunction &MF) override; 231 releaseMemory()232 void releaseMemory() override { 233 Wrapper.releaseMemory(); 234 Wrapper.setComputed(false); 235 } 236 }; 237 238 } // namespace llvm 239 240 #endif 241