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//===- llvm/CodeGen/CriticalAntiDepBreaker.h - Anti-Dep Support -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the CriticalAntiDepBreaker class, which
// implements register anti-dependence breaking along a blocks
// critical path during post-RA scheduler.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H
#define LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H
#include "llvm/ADT/BitVector.h"
#include "llvm/CodeGen/AntiDepBreaker.h"
#include "llvm/Support/Compiler.h"
#include <map>
#include <vector>
namespace llvm {
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MachineOperand;
class MachineRegisterInfo;
class RegisterClassInfo;
class TargetInstrInfo;
class TargetRegisterClass;
class TargetRegisterInfo;
class LLVM_LIBRARY_VISIBILITY CriticalAntiDepBreaker : public AntiDepBreaker {
MachineFunction& MF;
MachineRegisterInfo &MRI;
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
const RegisterClassInfo &RegClassInfo;
/// The set of allocatable registers.
/// We'll be ignoring anti-dependencies on non-allocatable registers,
/// because they may not be safe to break.
const BitVector AllocatableSet;
/// For live regs that are only used in one register class in a
/// live range, the register class. If the register is not live, the
/// corresponding value is null. If the register is live but used in
/// multiple register classes, the corresponding value is -1 casted to a
/// pointer.
std::vector<const TargetRegisterClass *> Classes;
/// Map registers to all their references within a live range.
std::multimap<unsigned, MachineOperand *> RegRefs;
using RegRefIter =
std::multimap<unsigned, MachineOperand *>::const_iterator;
/// The index of the most recent kill (proceeding bottom-up),
/// or ~0u if the register is not live.
std::vector<unsigned> KillIndices;
/// The index of the most recent complete def (proceeding
/// bottom up), or ~0u if the register is live.
std::vector<unsigned> DefIndices;
/// A set of registers which are live and cannot be changed to
/// break anti-dependencies.
BitVector KeepRegs;
public:
CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo &RCI);
~CriticalAntiDepBreaker() override;
/// Initialize anti-dep breaking for a new basic block.
void StartBlock(MachineBasicBlock *BB) override;
/// Identifiy anti-dependencies along the critical path
/// of the ScheduleDAG and break them by renaming registers.
unsigned BreakAntiDependencies(const std::vector<SUnit> &SUnits,
MachineBasicBlock::iterator Begin,
MachineBasicBlock::iterator End,
unsigned InsertPosIndex,
DbgValueVector &DbgValues) override;
/// Update liveness information to account for the current
/// instruction, which will not be scheduled.
void Observe(MachineInstr &MI, unsigned Count,
unsigned InsertPosIndex) override;
/// Finish anti-dep breaking for a basic block.
void FinishBlock() override;
private:
void PrescanInstruction(MachineInstr &MI);
void ScanInstruction(MachineInstr &MI, unsigned Count);
bool isNewRegClobberedByRefs(RegRefIter RegRefBegin,
RegRefIter RegRefEnd,
unsigned NewReg);
unsigned findSuitableFreeRegister(RegRefIter RegRefBegin,
RegRefIter RegRefEnd,
unsigned AntiDepReg,
unsigned LastNewReg,
const TargetRegisterClass *RC,
SmallVectorImpl<unsigned> &Forbid);
};
} // end namespace llvm
#endif // LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H
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