190 lines
7.4 KiB
C++
190 lines
7.4 KiB
C++
//=- llvm/CodeGen/AggressiveAntiDepBreaker.h - Anti-Dep Support -*- C++ -*-=//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the AggressiveAntiDepBreaker class, which
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// implements register anti-dependence breaking during post-RA
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// scheduling. It attempts to break all anti-dependencies within a
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// block.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_AGGRESSIVEANTIDEPBREAKER_H
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#define LLVM_CODEGEN_AGGRESSIVEANTIDEPBREAKER_H
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#include "AntiDepBreaker.h"
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/Target/TargetSubtarget.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/ADT/BitVector.h"
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#include "llvm/ADT/SmallSet.h"
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namespace llvm {
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/// Class AggressiveAntiDepState
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/// Contains all the state necessary for anti-dep breaking. We place
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/// into a separate class so be can conveniently save/restore it to
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/// enable multi-pass anti-dep breaking.
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class AggressiveAntiDepState {
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public:
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/// RegisterReference - Information about a register reference
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/// within a liverange
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typedef struct {
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/// Operand - The registers operand
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MachineOperand *Operand;
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/// RC - The register class
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const TargetRegisterClass *RC;
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} RegisterReference;
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private:
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/// GroupNodes - Implements a disjoint-union data structure to
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/// form register groups. A node is represented by an index into
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/// the vector. A node can "point to" itself to indicate that it
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/// is the parent of a group, or point to another node to indicate
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/// that it is a member of the same group as that node.
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std::vector<unsigned> GroupNodes;
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/// GroupNodeIndices - For each register, the index of the GroupNode
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/// currently representing the group that the register belongs to.
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/// Register 0 is always represented by the 0 group, a group
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/// composed of registers that are not eligible for anti-aliasing.
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unsigned GroupNodeIndices[TargetRegisterInfo::FirstVirtualRegister];
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/// RegRefs - Map registers to all their references within a live range.
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std::multimap<unsigned, RegisterReference> RegRefs;
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/// KillIndices - The index of the most recent kill (proceding bottom-up),
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/// or ~0u if the register is not live.
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unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister];
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/// DefIndices - The index of the most recent complete def (proceding bottom
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/// up), or ~0u if the register is live.
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unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister];
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public:
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AggressiveAntiDepState(MachineBasicBlock *BB);
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/// GetKillIndices - Return the kill indices.
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unsigned *GetKillIndices() { return KillIndices; }
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/// GetDefIndices - Return the define indices.
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unsigned *GetDefIndices() { return DefIndices; }
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/// GetRegRefs - Return the RegRefs map.
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std::multimap<unsigned, RegisterReference>& GetRegRefs() { return RegRefs; }
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// GetGroup - Get the group for a register. The returned value is
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// the index of the GroupNode representing the group.
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unsigned GetGroup(unsigned Reg);
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// GetGroupRegs - Return a vector of the registers belonging to a
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// group. If RegRefs is non-NULL then only included referenced registers.
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void GetGroupRegs(
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unsigned Group,
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std::vector<unsigned> &Regs,
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std::multimap<unsigned, AggressiveAntiDepState::RegisterReference> *RegRefs);
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// UnionGroups - Union Reg1's and Reg2's groups to form a new
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// group. Return the index of the GroupNode representing the
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// group.
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unsigned UnionGroups(unsigned Reg1, unsigned Reg2);
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// LeaveGroup - Remove a register from its current group and place
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// it alone in its own group. Return the index of the GroupNode
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// representing the registers new group.
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unsigned LeaveGroup(unsigned Reg);
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/// IsLive - Return true if Reg is live
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bool IsLive(unsigned Reg);
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};
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/// Class AggressiveAntiDepBreaker
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class AggressiveAntiDepBreaker : public AntiDepBreaker {
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MachineFunction& MF;
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MachineRegisterInfo &MRI;
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const TargetRegisterInfo *TRI;
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/// AllocatableSet - The set of allocatable registers.
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/// We'll be ignoring anti-dependencies on non-allocatable registers,
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/// because they may not be safe to break.
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const BitVector AllocatableSet;
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/// CriticalPathSet - The set of registers that should only be
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/// renamed if they are on the critical path.
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BitVector CriticalPathSet;
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/// State - The state used to identify and rename anti-dependence
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/// registers.
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AggressiveAntiDepState *State;
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/// SavedState - The state for the start of an anti-dep
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/// region. Used to restore the state at the beginning of each
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/// pass
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AggressiveAntiDepState *SavedState;
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public:
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AggressiveAntiDepBreaker(MachineFunction& MFi,
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TargetSubtarget::RegClassVector& CriticalPathRCs);
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~AggressiveAntiDepBreaker();
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/// GetMaxTrials - As anti-dependencies are broken, additional
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/// dependencies may be exposed, so multiple passes are required.
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unsigned GetMaxTrials();
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/// NeedCandidates - Candidates required.
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bool NeedCandidates() { return true; }
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/// Start - Initialize anti-dep breaking for a new basic block.
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void StartBlock(MachineBasicBlock *BB);
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/// BreakAntiDependencies - Identifiy anti-dependencies along the critical path
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/// of the ScheduleDAG and break them by renaming registers.
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///
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unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
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CandidateMap& Candidates,
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MachineBasicBlock::iterator& Begin,
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MachineBasicBlock::iterator& End,
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unsigned InsertPosIndex);
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/// Observe - Update liveness information to account for the current
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/// instruction, which will not be scheduled.
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///
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void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex);
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/// Finish - Finish anti-dep breaking for a basic block.
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void FinishBlock();
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private:
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typedef std::map<const TargetRegisterClass *,
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TargetRegisterClass::const_iterator> RenameOrderType;
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/// IsImplicitDefUse - Return true if MO represents a register
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/// that is both implicitly used and defined in MI
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bool IsImplicitDefUse(MachineInstr *MI, MachineOperand& MO);
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/// GetPassthruRegs - If MI implicitly def/uses a register, then
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/// return that register and all subregisters.
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void GetPassthruRegs(MachineInstr *MI, std::set<unsigned>& PassthruRegs);
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void HandleLastUse(unsigned Reg, unsigned KillIdx, const char *tag);
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void PrescanInstruction(MachineInstr *MI, unsigned Count,
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std::set<unsigned>& PassthruRegs);
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void ScanInstruction(MachineInstr *MI, unsigned Count);
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BitVector GetRenameRegisters(unsigned Reg);
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bool FindSuitableFreeRegisters(unsigned AntiDepGroupIndex,
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RenameOrderType& RenameOrder,
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std::map<unsigned, unsigned> &RenameMap);
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};
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}
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#endif
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