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 /// \file 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/MachineFunctionPass.h" 20 #include "llvm/Support/Allocator.h" 21 #include "llvm/Support/CodeGen.h" 22 23 namespace llvm { 24 class MachineBasicBlock; 25 26 /// A class that wraps MachineInstrs and derives from FoldingSetNode in order to 27 /// be uniqued in a CSEMap. The tradeoff here is extra memory allocations for 28 /// UniqueMachineInstr vs making MachineInstr bigger. 29 class UniqueMachineInstr : public FoldingSetNode { 30 friend class GISelCSEInfo; 31 const MachineInstr *MI; 32 explicit UniqueMachineInstr(const MachineInstr *MI) : MI(MI) {} 33 34 public: 35 void Profile(FoldingSetNodeID &ID); 36 }; 37 38 // A CSE config for fully optimized builds. 39 class CSEConfigFull : public CSEConfigBase { 40 public: 41 virtual ~CSEConfigFull() = default; 42 bool shouldCSEOpc(unsigned Opc) override; 43 }; 44 45 // Commonly used for O0 config. 46 class CSEConfigConstantOnly : public CSEConfigBase { 47 public: 48 virtual ~CSEConfigConstantOnly() = default; 49 bool shouldCSEOpc(unsigned Opc) override; 50 }; 51 52 // Returns the standard expected CSEConfig for the given optimization level. 53 // We have this logic here so targets can make use of it from their derived 54 // TargetPassConfig, but can't put this logic into TargetPassConfig directly 55 // because the CodeGen library can't depend on GlobalISel. 56 std::unique_ptr<CSEConfigBase> 57 getStandardCSEConfigForOpt(CodeGenOptLevel Level); 58 59 /// The CSE Analysis object. 60 /// This installs itself as a delegate to the MachineFunction to track 61 /// new instructions as well as deletions. It however will not be able to 62 /// track instruction mutations. In such cases, recordNewInstruction should be 63 /// called (for eg inside MachineIRBuilder::recordInsertion). 64 /// Also because of how just the instruction can be inserted without adding any 65 /// operands to the instruction, instructions are uniqued and inserted lazily. 66 /// CSEInfo should assert when trying to enter an incomplete instruction into 67 /// the CSEMap. There is Opcode level granularity on which instructions can be 68 /// CSE'd and for now, only Generic instructions are CSEable. 69 class GISelCSEInfo : public GISelChangeObserver { 70 // Make it accessible only to CSEMIRBuilder. 71 friend class CSEMIRBuilder; 72 73 BumpPtrAllocator UniqueInstrAllocator; 74 FoldingSet<UniqueMachineInstr> CSEMap; 75 MachineRegisterInfo *MRI = nullptr; 76 MachineFunction *MF = nullptr; 77 std::unique_ptr<CSEConfigBase> CSEOpt; 78 /// Keep a cache of UniqueInstrs for each MachineInstr. In GISel, 79 /// often instructions are mutated (while their ID has completely changed). 80 /// Whenever mutation happens, invalidate the UniqueMachineInstr for the 81 /// MachineInstr 82 DenseMap<const MachineInstr *, UniqueMachineInstr *> InstrMapping; 83 84 /// Store instructions that are not fully formed in TemporaryInsts. 85 /// Also because CSE insertion happens lazily, we can remove insts from this 86 /// list and avoid inserting and then removing from the CSEMap. 87 GISelWorkList<8> TemporaryInsts; 88 89 // Only used in asserts. 90 DenseMap<unsigned, unsigned> OpcodeHitTable; 91 92 bool isUniqueMachineInstValid(const UniqueMachineInstr &UMI) const; 93 94 void invalidateUniqueMachineInstr(UniqueMachineInstr *UMI); 95 96 UniqueMachineInstr *getNodeIfExists(FoldingSetNodeID &ID, 97 MachineBasicBlock *MBB, void *&InsertPos); 98 99 /// Allocate and construct a new UniqueMachineInstr for MI and return. 100 UniqueMachineInstr *getUniqueInstrForMI(const MachineInstr *MI); 101 102 void insertNode(UniqueMachineInstr *UMI, void *InsertPos = nullptr); 103 104 /// Get the MachineInstr(Unique) if it exists already in the CSEMap and the 105 /// same MachineBasicBlock. 106 MachineInstr *getMachineInstrIfExists(FoldingSetNodeID &ID, 107 MachineBasicBlock *MBB, 108 void *&InsertPos); 109 110 /// Use this method to allocate a new UniqueMachineInstr for MI and insert it 111 /// into the CSEMap. MI should return true for shouldCSE(MI->getOpcode()) 112 void insertInstr(MachineInstr *MI, void *InsertPos = nullptr); 113 114 bool HandlingRecordedInstrs = false; 115 116 public: 117 GISelCSEInfo() = default; 118 119 virtual ~GISelCSEInfo(); 120 121 void setMF(MachineFunction &MF); 122 123 Error verify(); 124 125 /// Records a newly created inst in a list and lazily insert it to the CSEMap. 126 /// Sometimes, this method might be called with a partially constructed 127 /// MachineInstr, 128 // (right after BuildMI without adding any operands) - and in such cases, 129 // defer the hashing of the instruction to a later stage. 130 void recordNewInstruction(MachineInstr *MI); 131 132 /// Use this callback to inform CSE about a newly fully created instruction. 133 void handleRecordedInst(MachineInstr *MI); 134 135 /// Use this callback to insert all the recorded instructions. At this point, 136 /// all of these insts need to be fully constructed and should not be missing 137 /// any operands. 138 void handleRecordedInsts(); 139 140 /// Remove this inst from the CSE map. If this inst has not been inserted yet, 141 /// it will be removed from the Tempinsts list if it exists. 142 void handleRemoveInst(MachineInstr *MI); 143 144 void releaseMemory(); 145 146 void setCSEConfig(std::unique_ptr<CSEConfigBase> Opt) { 147 CSEOpt = std::move(Opt); 148 } 149 150 bool shouldCSE(unsigned Opc) const; 151 152 void analyze(MachineFunction &MF); 153 154 void countOpcodeHit(unsigned Opc); 155 156 void print(); 157 158 // Observer API 159 void erasingInstr(MachineInstr &MI) override; 160 void createdInstr(MachineInstr &MI) override; 161 void changingInstr(MachineInstr &MI) override; 162 void changedInstr(MachineInstr &MI) override; 163 }; 164 165 class TargetRegisterClass; 166 class RegisterBank; 167 168 // Simple builder class to easily profile properties about MIs. 169 class GISelInstProfileBuilder { 170 FoldingSetNodeID &ID; 171 const MachineRegisterInfo &MRI; 172 173 public: 174 GISelInstProfileBuilder(FoldingSetNodeID &ID, const MachineRegisterInfo &MRI) 175 : ID(ID), MRI(MRI) {} 176 // Profiling methods. 177 const GISelInstProfileBuilder &addNodeIDOpcode(unsigned Opc) const; 178 const GISelInstProfileBuilder &addNodeIDRegType(const LLT Ty) const; 179 const GISelInstProfileBuilder &addNodeIDRegType(const Register) const; 180 181 const GISelInstProfileBuilder & 182 addNodeIDRegType(const TargetRegisterClass *RC) const; 183 const GISelInstProfileBuilder &addNodeIDRegType(const RegisterBank *RB) const; 184 185 const GISelInstProfileBuilder &addNodeIDRegNum(Register Reg) const; 186 187 const GISelInstProfileBuilder &addNodeIDReg(Register Reg) const; 188 189 const GISelInstProfileBuilder &addNodeIDImmediate(int64_t Imm) const; 190 const GISelInstProfileBuilder & 191 addNodeIDMBB(const MachineBasicBlock *MBB) const; 192 193 const GISelInstProfileBuilder & 194 addNodeIDMachineOperand(const MachineOperand &MO) const; 195 196 const GISelInstProfileBuilder &addNodeIDFlag(unsigned Flag) const; 197 const GISelInstProfileBuilder &addNodeID(const MachineInstr *MI) const; 198 }; 199 200 /// Simple wrapper that does the following. 201 /// 1) Lazily evaluate the MachineFunction to compute CSEable instructions. 202 /// 2) Allows configuration of which instructions are CSEd through CSEConfig 203 /// object. Provides a method called get which takes a CSEConfig object. 204 class GISelCSEAnalysisWrapper { 205 GISelCSEInfo Info; 206 MachineFunction *MF = nullptr; 207 bool AlreadyComputed = false; 208 209 public: 210 /// Takes a CSEConfigBase object that defines what opcodes get CSEd. 211 /// If CSEConfig is already set, and the CSE Analysis has been preserved, 212 /// it will not use the new CSEOpt(use Recompute to force using the new 213 /// CSEOpt). 214 GISelCSEInfo &get(std::unique_ptr<CSEConfigBase> CSEOpt, 215 bool ReCompute = false); 216 void setMF(MachineFunction &MFunc) { MF = &MFunc; } 217 void setComputed(bool Computed) { AlreadyComputed = Computed; } 218 void releaseMemory() { Info.releaseMemory(); } 219 }; 220 221 /// The actual analysis pass wrapper. 222 class GISelCSEAnalysisWrapperPass : public MachineFunctionPass { 223 GISelCSEAnalysisWrapper Wrapper; 224 225 public: 226 static char ID; 227 GISelCSEAnalysisWrapperPass(); 228 229 void getAnalysisUsage(AnalysisUsage &AU) const override; 230 231 const GISelCSEAnalysisWrapper &getCSEWrapper() const { return Wrapper; } 232 GISelCSEAnalysisWrapper &getCSEWrapper() { return Wrapper; } 233 234 bool runOnMachineFunction(MachineFunction &MF) override; 235 236 void releaseMemory() override { 237 Wrapper.releaseMemory(); 238 Wrapper.setComputed(false); 239 } 240 }; 241 242 } // namespace llvm 243 244 #endif 245