CriticalAntiDepBreaker.h revision 207618
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 "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#include <map> 29 30namespace llvm { 31 class CriticalAntiDepBreaker : public AntiDepBreaker { 32 MachineFunction& MF; 33 MachineRegisterInfo &MRI; 34 const TargetRegisterInfo *TRI; 35 36 /// AllocatableSet - The set of allocatable registers. 37 /// We'll be ignoring anti-dependencies on non-allocatable registers, 38 /// because they may not be safe to break. 39 const BitVector AllocatableSet; 40 41 /// Classes - For live regs that are only used in one register class in a 42 /// live range, the register class. If the register is not live, the 43 /// corresponding value is null. If the register is live but used in 44 /// multiple register classes, the corresponding value is -1 casted to a 45 /// pointer. 46 const TargetRegisterClass * 47 Classes[TargetRegisterInfo::FirstVirtualRegister]; 48 49 /// RegRegs - Map registers to all their references within a live range. 50 std::multimap<unsigned, MachineOperand *> RegRefs; 51 52 /// KillIndices - The index of the most recent kill (proceding bottom-up), 53 /// or ~0u if the register is not live. 54 unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister]; 55 56 /// DefIndices - The index of the most recent complete def (proceding bottom 57 /// up), or ~0u if the register is live. 58 unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister]; 59 60 /// KeepRegs - A set of registers which are live and cannot be changed to 61 /// break anti-dependencies. 62 SmallSet<unsigned, 4> KeepRegs; 63 64 public: 65 CriticalAntiDepBreaker(MachineFunction& MFi); 66 ~CriticalAntiDepBreaker(); 67 68 /// Start - Initialize anti-dep breaking for a new basic block. 69 void StartBlock(MachineBasicBlock *BB); 70 71 /// BreakAntiDependencies - Identifiy anti-dependencies along the critical 72 /// path 73 /// of the ScheduleDAG and break them by renaming registers. 74 /// 75 unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits, 76 MachineBasicBlock::iterator Begin, 77 MachineBasicBlock::iterator End, 78 unsigned InsertPosIndex); 79 80 /// Observe - Update liveness information to account for the current 81 /// instruction, which will not be scheduled. 82 /// 83 void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex); 84 85 /// Finish - Finish anti-dep breaking for a basic block. 86 void FinishBlock(); 87 88 private: 89 void PrescanInstruction(MachineInstr *MI); 90 void ScanInstruction(MachineInstr *MI, unsigned Count); 91 unsigned findSuitableFreeRegister(MachineInstr *MI, 92 unsigned AntiDepReg, 93 unsigned LastNewReg, 94 const TargetRegisterClass *); 95 }; 96} 97 98#endif 99