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 "RegisterClassInfo.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/ScheduleDAG.h" 26 #include "llvm/ADT/BitVector.h" 27 #include "llvm/ADT/SmallSet.h" 28 #include <map> 29 30 namespace llvm { 31 class RegisterClassInfo; 32 class TargetInstrInfo; 33 class TargetRegisterInfo; 34 35 class CriticalAntiDepBreaker : public AntiDepBreaker { 36 MachineFunction& MF; 37 MachineRegisterInfo &MRI; 38 const TargetInstrInfo *TII; 39 const TargetRegisterInfo *TRI; 40 const RegisterClassInfo &RegClassInfo; 41 42 /// AllocatableSet - The set of allocatable registers. 43 /// We'll be ignoring anti-dependencies on non-allocatable registers, 44 /// because they may not be safe to break. 45 const BitVector AllocatableSet; 46 47 /// Classes - For live regs that are only used in one register class in a 48 /// live range, the register class. If the register is not live, the 49 /// corresponding value is null. If the register is live but used in 50 /// multiple register classes, the corresponding value is -1 casted to a 51 /// pointer. 52 std::vector<const TargetRegisterClass*> Classes; 53 54 /// RegRefs - Map registers to all their references within a live range. 55 std::multimap<unsigned, MachineOperand *> RegRefs; 56 typedef std::multimap<unsigned, MachineOperand *>::const_iterator 57 RegRefIter; 58 59 /// KillIndices - The index of the most recent kill (proceding bottom-up), 60 /// or ~0u if the register is not live. 61 std::vector<unsigned> KillIndices; 62 63 /// DefIndices - The index of the most recent complete def (proceding bottom 64 /// up), or ~0u if the register is live. 65 std::vector<unsigned> DefIndices; 66 67 /// KeepRegs - A set of registers which are live and cannot be changed to 68 /// break anti-dependencies. 69 SmallSet<unsigned, 4> KeepRegs; 70 71 public: 72 CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo&); 73 ~CriticalAntiDepBreaker(); 74 75 /// Start - Initialize anti-dep breaking for a new basic block. 76 void StartBlock(MachineBasicBlock *BB); 77 78 /// BreakAntiDependencies - Identifiy anti-dependencies along the critical 79 /// path 80 /// of the ScheduleDAG and break them by renaming registers. 81 /// 82 unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits, 83 MachineBasicBlock::iterator Begin, 84 MachineBasicBlock::iterator End, 85 unsigned InsertPosIndex, 86 DbgValueVector &DbgValues); 87 88 /// Observe - Update liveness information to account for the current 89 /// instruction, which will not be scheduled. 90 /// 91 void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex); 92 93 /// Finish - Finish anti-dep breaking for a basic block. 94 void FinishBlock(); 95 96 private: 97 void PrescanInstruction(MachineInstr *MI); 98 void ScanInstruction(MachineInstr *MI, unsigned Count); 99 bool isNewRegClobberedByRefs(RegRefIter RegRefBegin, 100 RegRefIter RegRefEnd, 101 unsigned NewReg); 102 unsigned findSuitableFreeRegister(RegRefIter RegRefBegin, 103 RegRefIter RegRefEnd, 104 unsigned AntiDepReg, 105 unsigned LastNewReg, 106 const TargetRegisterClass *RC); 107 }; 108 } 109 110 #endif 111
