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//===- llvm/CodeGen/GlobalISel/CSEInfo.h ------------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
/// \file
/// Provides analysis for continuously CSEing during GISel passes.
#include "llvm/ADT/FoldingSet.h"
#include "llvm/CodeGen/CSEConfigBase.h"
#include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
#include "llvm/CodeGen/GlobalISel/GISelWorkList.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/CodeGen.h"
namespace llvm {
class MachineBasicBlock;
/// A class that wraps MachineInstrs and derives from FoldingSetNode in order to
/// be uniqued in a CSEMap. The tradeoff here is extra memory allocations for
/// UniqueMachineInstr vs making MachineInstr bigger.
class UniqueMachineInstr : public FoldingSetNode {
friend class GISelCSEInfo;
const MachineInstr *MI;
explicit UniqueMachineInstr(const MachineInstr *MI) : MI(MI) {}
void Profile(FoldingSetNodeID &ID);
// A CSE config for fully optimized builds.
class CSEConfigFull : public CSEConfigBase {
virtual ~CSEConfigFull() = default;
bool shouldCSEOpc(unsigned Opc) override;
// Commonly used for O0 config.
class CSEConfigConstantOnly : public CSEConfigBase {
virtual ~CSEConfigConstantOnly() = default;
bool shouldCSEOpc(unsigned Opc) override;
// Returns the standard expected CSEConfig for the given optimization level.
// We have this logic here so targets can make use of it from their derived
// TargetPassConfig, but can't put this logic into TargetPassConfig directly
// because the CodeGen library can't depend on GlobalISel.
getStandardCSEConfigForOpt(CodeGenOptLevel Level);
/// The CSE Analysis object.
/// This installs itself as a delegate to the MachineFunction to track
/// new instructions as well as deletions. It however will not be able to
/// track instruction mutations. In such cases, recordNewInstruction should be
/// called (for eg inside MachineIRBuilder::recordInsertion).
/// Also because of how just the instruction can be inserted without adding any
/// operands to the instruction, instructions are uniqued and inserted lazily.
/// CSEInfo should assert when trying to enter an incomplete instruction into
/// the CSEMap. There is Opcode level granularity on which instructions can be
/// CSE'd and for now, only Generic instructions are CSEable.
class GISelCSEInfo : public GISelChangeObserver {
// Make it accessible only to CSEMIRBuilder.
friend class CSEMIRBuilder;
BumpPtrAllocator UniqueInstrAllocator;
FoldingSet<UniqueMachineInstr> CSEMap;
MachineRegisterInfo *MRI = nullptr;
MachineFunction *MF = nullptr;
std::unique_ptr<CSEConfigBase> CSEOpt;
/// Keep a cache of UniqueInstrs for each MachineInstr. In GISel,
/// often instructions are mutated (while their ID has completely changed).
/// Whenever mutation happens, invalidate the UniqueMachineInstr for the
/// MachineInstr
DenseMap<const MachineInstr *, UniqueMachineInstr *> InstrMapping;
/// Store instructions that are not fully formed in TemporaryInsts.
/// Also because CSE insertion happens lazily, we can remove insts from this
/// list and avoid inserting and then removing from the CSEMap.
GISelWorkList<8> TemporaryInsts;
// Only used in asserts.
DenseMap<unsigned, unsigned> OpcodeHitTable;
bool isUniqueMachineInstValid(const UniqueMachineInstr &UMI) const;
void invalidateUniqueMachineInstr(UniqueMachineInstr *UMI);
UniqueMachineInstr *getNodeIfExists(FoldingSetNodeID &ID,
MachineBasicBlock *MBB, void *&InsertPos);
/// Allocate and construct a new UniqueMachineInstr for MI and return.
UniqueMachineInstr *getUniqueInstrForMI(const MachineInstr *MI);
void insertNode(UniqueMachineInstr *UMI, void *InsertPos = nullptr);
/// Get the MachineInstr(Unique) if it exists already in the CSEMap and the
/// same MachineBasicBlock.
MachineInstr *getMachineInstrIfExists(FoldingSetNodeID &ID,
MachineBasicBlock *MBB,
void *&InsertPos);
/// Use this method to allocate a new UniqueMachineInstr for MI and insert it
/// into the CSEMap. MI should return true for shouldCSE(MI->getOpcode())
void insertInstr(MachineInstr *MI, void *InsertPos = nullptr);
bool HandlingRecordedInstrs = false;
GISelCSEInfo() = default;
virtual ~GISelCSEInfo();
void setMF(MachineFunction &MF);
Error verify();
/// Records a newly created inst in a list and lazily insert it to the CSEMap.
/// Sometimes, this method might be called with a partially constructed
/// MachineInstr,
// (right after BuildMI without adding any operands) - and in such cases,
// defer the hashing of the instruction to a later stage.
void recordNewInstruction(MachineInstr *MI);
/// Use this callback to inform CSE about a newly fully created instruction.
void handleRecordedInst(MachineInstr *MI);
/// Use this callback to insert all the recorded instructions. At this point,
/// all of these insts need to be fully constructed and should not be missing
/// any operands.
void handleRecordedInsts();
/// Remove this inst from the CSE map. If this inst has not been inserted yet,
/// it will be removed from the Tempinsts list if it exists.
void handleRemoveInst(MachineInstr *MI);
void releaseMemory();
void setCSEConfig(std::unique_ptr<CSEConfigBase> Opt) {
CSEOpt = std::move(Opt);
bool shouldCSE(unsigned Opc) const;
void analyze(MachineFunction &MF);
void countOpcodeHit(unsigned Opc);
void print();
// Observer API
void erasingInstr(MachineInstr &MI) override;
void createdInstr(MachineInstr &MI) override;
void changingInstr(MachineInstr &MI) override;
void changedInstr(MachineInstr &MI) override;
class TargetRegisterClass;
class RegisterBank;
// Simple builder class to easily profile properties about MIs.
class GISelInstProfileBuilder {
FoldingSetNodeID &ID;
const MachineRegisterInfo &MRI;
GISelInstProfileBuilder(FoldingSetNodeID &ID, const MachineRegisterInfo &MRI)
: ID(ID), MRI(MRI) {}
// Profiling methods.
const GISelInstProfileBuilder &addNodeIDOpcode(unsigned Opc) const;
const GISelInstProfileBuilder &addNodeIDRegType(const LLT Ty) const;
const GISelInstProfileBuilder &addNodeIDRegType(const Register) const;
const GISelInstProfileBuilder &
addNodeIDRegType(const TargetRegisterClass *RC) const;
const GISelInstProfileBuilder &addNodeIDRegType(const RegisterBank *RB) const;
const GISelInstProfileBuilder &addNodeIDRegNum(Register Reg) const;
const GISelInstProfileBuilder &addNodeIDReg(Register Reg) const;
const GISelInstProfileBuilder &addNodeIDImmediate(int64_t Imm) const;
const GISelInstProfileBuilder &
addNodeIDMBB(const MachineBasicBlock *MBB) const;
const GISelInstProfileBuilder &
addNodeIDMachineOperand(const MachineOperand &MO) const;
const GISelInstProfileBuilder &addNodeIDFlag(unsigned Flag) const;
const GISelInstProfileBuilder &addNodeID(const MachineInstr *MI) const;
/// Simple wrapper that does the following.
/// 1) Lazily evaluate the MachineFunction to compute CSEable instructions.
/// 2) Allows configuration of which instructions are CSEd through CSEConfig
/// object. Provides a method called get which takes a CSEConfig object.
class GISelCSEAnalysisWrapper {
GISelCSEInfo Info;
MachineFunction *MF = nullptr;
bool AlreadyComputed = false;
/// Takes a CSEConfigBase object that defines what opcodes get CSEd.
/// If CSEConfig is already set, and the CSE Analysis has been preserved,
/// it will not use the new CSEOpt(use Recompute to force using the new
/// CSEOpt).
GISelCSEInfo &get(std::unique_ptr<CSEConfigBase> CSEOpt,
bool ReCompute = false);
void setMF(MachineFunction &MFunc) { MF = &MFunc; }
void setComputed(bool Computed) { AlreadyComputed = Computed; }
void releaseMemory() { Info.releaseMemory(); }
/// The actual analysis pass wrapper.
class GISelCSEAnalysisWrapperPass : public MachineFunctionPass {
GISelCSEAnalysisWrapper Wrapper;
static char ID;
void getAnalysisUsage(AnalysisUsage &AU) const override;
const GISelCSEAnalysisWrapper &getCSEWrapper() const { return Wrapper; }
GISelCSEAnalysisWrapper &getCSEWrapper() { return Wrapper; }
bool runOnMachineFunction(MachineFunction &MF) override;
void releaseMemory() override {
} // namespace llvm