1 //===- llvm/CodeGen/CriticalAntiDepBreaker.h - Anti-Dep Support -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the CriticalAntiDepBreaker class, which
11 // implements register anti-dependence breaking along a blocks
12 // critical path during post-RA scheduler.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H
17 #define LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H
19 #include "AntiDepBreaker.h"
20 #include "llvm/ADT/BitVector.h"
21 #include "llvm/Support/Compiler.h"
27 class MachineBasicBlock;
28 class MachineFunction;
31 class MachineRegisterInfo;
32 class RegisterClassInfo;
33 class TargetInstrInfo;
34 class TargetRegisterClass;
35 class TargetRegisterInfo;
37 class LLVM_LIBRARY_VISIBILITY CriticalAntiDepBreaker : public AntiDepBreaker {
39 MachineRegisterInfo &MRI;
40 const TargetInstrInfo *TII;
41 const TargetRegisterInfo *TRI;
42 const RegisterClassInfo &RegClassInfo;
44 /// The set of allocatable registers.
45 /// We'll be ignoring anti-dependencies on non-allocatable registers,
46 /// because they may not be safe to break.
47 const BitVector AllocatableSet;
49 /// For live regs that are only used in one register class in a
50 /// live range, the register class. If the register is not live, the
51 /// corresponding value is null. If the register is live but used in
52 /// multiple register classes, the corresponding value is -1 casted to a
54 std::vector<const TargetRegisterClass *> Classes;
56 /// Map registers to all their references within a live range.
57 std::multimap<unsigned, MachineOperand *> RegRefs;
60 std::multimap<unsigned, MachineOperand *>::const_iterator;
62 /// The index of the most recent kill (proceeding bottom-up),
63 /// or ~0u if the register is not live.
64 std::vector<unsigned> KillIndices;
66 /// The index of the most recent complete def (proceeding
67 /// bottom up), or ~0u if the register is live.
68 std::vector<unsigned> DefIndices;
70 /// A set of registers which are live and cannot be changed to
71 /// break anti-dependencies.
75 CriticalAntiDepBreaker(MachineFunction& MFi, const RegisterClassInfo &RCI);
76 ~CriticalAntiDepBreaker() override;
78 /// Initialize anti-dep breaking for a new basic block.
79 void StartBlock(MachineBasicBlock *BB) override;
81 /// Identifiy anti-dependencies along the critical path
82 /// of the ScheduleDAG and break them by renaming registers.
83 unsigned BreakAntiDependencies(const std::vector<SUnit> &SUnits,
84 MachineBasicBlock::iterator Begin,
85 MachineBasicBlock::iterator End,
86 unsigned InsertPosIndex,
87 DbgValueVector &DbgValues) override;
89 /// Update liveness information to account for the current
90 /// instruction, which will not be scheduled.
91 void Observe(MachineInstr &MI, unsigned Count,
92 unsigned InsertPosIndex) override;
94 /// Finish anti-dep breaking for a basic block.
95 void FinishBlock() override;
98 void PrescanInstruction(MachineInstr &MI);
99 void ScanInstruction(MachineInstr &MI, unsigned Count);
100 bool isNewRegClobberedByRefs(RegRefIter RegRefBegin,
101 RegRefIter RegRefEnd,
103 unsigned findSuitableFreeRegister(RegRefIter RegRefBegin,
104 RegRefIter RegRefEnd,
107 const TargetRegisterClass *RC,
108 SmallVectorImpl<unsigned> &Forbid);
111 } // end namespace llvm
113 #endif // LLVM_LIB_CODEGEN_CRITICALANTIDEPBREAKER_H