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//==- llvm/CodeGen/AggressiveAntiDepBreaker.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 AggressiveAntiDepBreaker class, which
// implements register anti-dependence breaking during post-RA
// scheduling. It attempts to break all anti-dependencies within a
// block.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_AGGRESSIVEANTIDEPBREAKER_H
#define LLVM_LIB_CODEGEN_AGGRESSIVEANTIDEPBREAKER_H
#include "llvm/ADT/BitVector.h"
#include "llvm/CodeGen/AntiDepBreaker.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/Support/Compiler.h"
#include <map>
#include <set>
#include <vector>
namespace llvm {
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MachineOperand;
class MachineRegisterInfo;
class RegisterClassInfo;
class TargetInstrInfo;
class TargetRegisterClass;
class TargetRegisterInfo;
/// Contains all the state necessary for anti-dep breaking.
class LLVM_LIBRARY_VISIBILITY AggressiveAntiDepState {
public:
/// Information about a register reference within a liverange
struct RegisterReference {
/// The registers operand
MachineOperand *Operand;
/// The register class
const TargetRegisterClass *RC;
};
private:
/// Number of non-virtual target registers (i.e. TRI->getNumRegs()).
const unsigned NumTargetRegs;
/// Implements a disjoint-union data structure to
/// form register groups. A node is represented by an index into
/// the vector. A node can "point to" itself to indicate that it
/// is the parent of a group, or point to another node to indicate
/// that it is a member of the same group as that node.
std::vector<unsigned> GroupNodes;
/// For each register, the index of the GroupNode
/// currently representing the group that the register belongs to.
/// Register 0 is always represented by the 0 group, a group
/// composed of registers that are not eligible for anti-aliasing.
std::vector<unsigned> GroupNodeIndices;
/// Map registers to all their references within a live range.
std::multimap<unsigned, RegisterReference> RegRefs;
/// 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;
public:
AggressiveAntiDepState(const unsigned TargetRegs, MachineBasicBlock *BB);
/// Return the kill indices.
std::vector<unsigned> &GetKillIndices() { return KillIndices; }
/// Return the define indices.
std::vector<unsigned> &GetDefIndices() { return DefIndices; }
/// Return the RegRefs map.
std::multimap<unsigned, RegisterReference>& GetRegRefs() { return RegRefs; }
// Get the group for a register. The returned value is
// the index of the GroupNode representing the group.
unsigned GetGroup(unsigned Reg);
// Return a vector of the registers belonging to a group.
// If RegRefs is non-NULL then only included referenced registers.
void GetGroupRegs(
unsigned Group,
std::vector<unsigned> &Regs,
std::multimap<unsigned,
AggressiveAntiDepState::RegisterReference> *RegRefs);
// Union Reg1's and Reg2's groups to form a new group.
// Return the index of the GroupNode representing the group.
unsigned UnionGroups(unsigned Reg1, unsigned Reg2);
// Remove a register from its current group and place
// it alone in its own group. Return the index of the GroupNode
// representing the registers new group.
unsigned LeaveGroup(unsigned Reg);
/// Return true if Reg is live.
bool IsLive(unsigned Reg);
};
class LLVM_LIBRARY_VISIBILITY AggressiveAntiDepBreaker
: public AntiDepBreaker {
MachineFunction &MF;
MachineRegisterInfo &MRI;
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
const RegisterClassInfo &RegClassInfo;
/// The set of registers that should only be
/// renamed if they are on the critical path.
BitVector CriticalPathSet;
/// The state used to identify and rename anti-dependence registers.
AggressiveAntiDepState *State = nullptr;
public:
AggressiveAntiDepBreaker(MachineFunction &MFi,
const RegisterClassInfo &RCI,
TargetSubtargetInfo::RegClassVector& CriticalPathRCs);
~AggressiveAntiDepBreaker() 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:
/// Keep track of a position in the allocation order for each regclass.
using RenameOrderType = std::map<const TargetRegisterClass *, unsigned>;
/// Return true if MO represents a register
/// that is both implicitly used and defined in MI
bool IsImplicitDefUse(MachineInstr &MI, MachineOperand &MO);
/// If MI implicitly def/uses a register, then
/// return that register and all subregisters.
void GetPassthruRegs(MachineInstr &MI, std::set<unsigned> &PassthruRegs);
void HandleLastUse(unsigned Reg, unsigned KillIdx, const char *tag,
const char *header = nullptr,
const char *footer = nullptr);
void PrescanInstruction(MachineInstr &MI, unsigned Count,
std::set<unsigned> &PassthruRegs);
void ScanInstruction(MachineInstr &MI, unsigned Count);
BitVector GetRenameRegisters(unsigned Reg);
bool FindSuitableFreeRegisters(unsigned AntiDepGroupIndex,
RenameOrderType& RenameOrder,
std::map<unsigned, unsigned> &RenameMap);
};
} // end namespace llvm
#endif // LLVM_LIB_CODEGEN_AGGRESSIVEANTIDEPBREAKER_H
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