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_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H 17 #define LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H 18 19 #include "AntiDepBreaker.h" 20 #include "llvm/ADT/BitVector.h" 21 #include "llvm/CodeGen/MachineBasicBlock.h" 22 #include "llvm/CodeGen/MachineFrameInfo.h" 23 #include "llvm/CodeGen/MachineFunction.h" 24 #include "llvm/CodeGen/MachineRegisterInfo.h" 25 #include "llvm/CodeGen/RegisterClassInfo.h" 26 #include "llvm/CodeGen/ScheduleDAG.h" 27 #include <map> 28 29 namespace llvm { 30 class RegisterClassInfo; 31 class TargetInstrInfo; 32 class TargetRegisterInfo; 33 34 class LLVM_LIBRARY_VISIBILITY CriticalAntiDepBreaker : public AntiDepBreaker { 35 MachineFunction& MF; 36 MachineRegisterInfo &MRI; 37 const TargetInstrInfo *TII; 38 const TargetRegisterInfo *TRI; 39 const RegisterClassInfo &RegClassInfo; 40 41 /// The set of allocatable registers. 42 /// We'll be ignoring anti-dependencies on non-allocatable registers, 43 /// because they may not be safe to break. 44 const BitVector AllocatableSet; 45 46 /// For live regs that are only used in one register class in a 47 /// live range, the register class. If the register is not live, the 48 /// corresponding value is null. If the register is live but used in 49 /// multiple register classes, the corresponding value is -1 casted to a 50 /// pointer. 51 std::vector<const TargetRegisterClass*> Classes; 52 53 /// Map registers to all their references within a live range. 54 std::multimap<unsigned, MachineOperand *> RegRefs; 55 typedef std::multimap<unsigned, MachineOperand *>::const_iterator 56 RegRefIter; 57 58 /// The index of the most recent kill (proceeding bottom-up), 59 /// or ~0u if the register is not live. 60 std::vector<unsigned> KillIndices; 61 62 /// The index of the most recent complete def (proceeding 63 /// bottom up), or ~0u if the register is live. 64 std::vector<unsigned> DefIndices; 65 66 /// A set of registers which are live and cannot be changed to 67 /// break anti-dependencies. 68 BitVector KeepRegs; 69 70 public: 71 CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo&); 72 ~CriticalAntiDepBreaker() override; 73 74 /// Initialize anti-dep breaking for a new basic block. 75 void StartBlock(MachineBasicBlock *BB) override; 76 77 /// Identifiy anti-dependencies along the critical path 78 /// of the ScheduleDAG and break them by renaming registers. 79 unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits, 80 MachineBasicBlock::iterator Begin, 81 MachineBasicBlock::iterator End, 82 unsigned InsertPosIndex, 83 DbgValueVector &DbgValues) override; 84 85 /// Update liveness information to account for the current 86 /// instruction, which will not be scheduled. 87 void Observe(MachineInstr *MI, unsigned Count, 88 unsigned InsertPosIndex) override; 89 90 /// Finish anti-dep breaking for a basic block. 91 void FinishBlock() override; 92 93 private: 94 void PrescanInstruction(MachineInstr *MI); 95 void ScanInstruction(MachineInstr *MI, unsigned Count); 96 bool isNewRegClobberedByRefs(RegRefIter RegRefBegin, 97 RegRefIter RegRefEnd, 98 unsigned NewReg); 99 unsigned findSuitableFreeRegister(RegRefIter RegRefBegin, 100 RegRefIter RegRefEnd, 101 unsigned AntiDepReg, 102 unsigned LastNewReg, 103 const TargetRegisterClass *RC, 104 SmallVectorImpl<unsigned> &Forbid); 105 }; 106 } 107 108 #endif 109
