CriticalAntiDepBreaker.h revision e10deca33e74a7c70ab585f78eee3fb52937f668
1//=- llvm/CodeGen/CriticalAntiDepBreaker.h - Anti-Dep Support -*- C++ -*-=// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the CriticalAntiDepBreaker class, which 11// implements register anti-dependence breaking along a blocks 12// critical path during post-RA scheduler. 13// 14//===----------------------------------------------------------------------===// 15 16#ifndef LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H 17#define LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H 18 19#include "llvm/CodeGen/AntiDepBreaker.h" 20#include "llvm/CodeGen/MachineBasicBlock.h" 21#include "llvm/CodeGen/MachineFrameInfo.h" 22#include "llvm/CodeGen/MachineFunction.h" 23#include "llvm/CodeGen/MachineRegisterInfo.h" 24#include "llvm/CodeGen/ScheduleDAG.h" 25#include "llvm/Target/TargetRegisterInfo.h" 26#include "llvm/ADT/BitVector.h" 27#include "llvm/ADT/SmallSet.h" 28 29namespace llvm { 30 class CriticalAntiDepBreaker : public AntiDepBreaker { 31 MachineFunction& MF; 32 MachineRegisterInfo &MRI; 33 const TargetRegisterInfo *TRI; 34 35 /// AllocatableSet - The set of allocatable registers. 36 /// We'll be ignoring anti-dependencies on non-allocatable registers, 37 /// because they may not be safe to break. 38 const BitVector AllocatableSet; 39 40 /// Classes - For live regs that are only used in one register class in a 41 /// live range, the register class. If the register is not live, the 42 /// corresponding value is null. If the register is live but used in 43 /// multiple register classes, the corresponding value is -1 casted to a 44 /// pointer. 45 const TargetRegisterClass * 46 Classes[TargetRegisterInfo::FirstVirtualRegister]; 47 48 /// RegRegs - Map registers to all their references within a live range. 49 std::multimap<unsigned, MachineOperand *> RegRefs; 50 51 /// KillIndices - The index of the most recent kill (proceding bottom-up), 52 /// or ~0u if the register is not live. 53 unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister]; 54 55 /// DefIndices - The index of the most recent complete def (proceding bottom 56 /// up), or ~0u if the register is live. 57 unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister]; 58 59 /// KeepRegs - A set of registers which are live and cannot be changed to 60 /// break anti-dependencies. 61 SmallSet<unsigned, 4> KeepRegs; 62 63 public: 64 CriticalAntiDepBreaker(MachineFunction& MFi); 65 ~CriticalAntiDepBreaker(); 66 67 /// GetMaxTrials - Critical path anti-dependence breaking requires 68 /// only a single pass 69 unsigned GetMaxTrials() { return 1; } 70 71 /// Start - Initialize anti-dep breaking for a new basic block. 72 void StartBlock(MachineBasicBlock *BB); 73 74 /// BreakAntiDependencies - Identifiy anti-dependencies along the critical path 75 /// of the ScheduleDAG and break them by renaming registers. 76 /// 77 unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits, 78 MachineBasicBlock::iterator& Begin, 79 MachineBasicBlock::iterator& End, 80 unsigned InsertPosIndex); 81 82 /// Observe - Update liveness information to account for the current 83 /// instruction, which will not be scheduled. 84 /// 85 void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex); 86 87 /// Finish - Finish anti-dep breaking for a basic block. 88 void FinishBlock(); 89 90 private: 91 void PrescanInstruction(MachineInstr *MI); 92 void ScanInstruction(MachineInstr *MI, unsigned Count); 93 unsigned findSuitableFreeRegister(unsigned AntiDepReg, 94 unsigned LastNewReg, 95 const TargetRegisterClass *); 96 }; 97} 98 99#endif 100