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_CODEGEN_CRITICALANTIDEPBREAKER_H
17 #define LLVM_CODEGEN_CRITICALANTIDEPBREAKER_H
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/ADT/BitVector.h"
26 #include "llvm/ADT/SmallSet.h"
30 class TargetInstrInfo;
31 class TargetRegisterInfo;
33 class CriticalAntiDepBreaker : public AntiDepBreaker {
35 MachineRegisterInfo &MRI;
36 const TargetInstrInfo *TII;
37 const TargetRegisterInfo *TRI;
39 /// AllocatableSet - The set of allocatable registers.
40 /// We'll be ignoring anti-dependencies on non-allocatable registers,
41 /// because they may not be safe to break.
42 const BitVector AllocatableSet;
44 /// Classes - For live regs that are only used in one register class in a
45 /// live range, the register class. If the register is not live, the
46 /// corresponding value is null. If the register is live but used in
47 /// multiple register classes, the corresponding value is -1 casted to a
49 std::vector<const TargetRegisterClass*> Classes;
51 /// RegRegs - Map registers to all their references within a live range.
52 std::multimap<unsigned, MachineOperand *> RegRefs;
54 /// KillIndices - The index of the most recent kill (proceding bottom-up),
55 /// or ~0u if the register is not live.
56 std::vector<unsigned> KillIndices;
58 /// DefIndices - The index of the most recent complete def (proceding bottom
59 /// up), or ~0u if the register is live.
60 std::vector<unsigned> DefIndices;
62 /// KeepRegs - A set of registers which are live and cannot be changed to
63 /// break anti-dependencies.
64 SmallSet<unsigned, 4> KeepRegs;
67 CriticalAntiDepBreaker(MachineFunction& MFi);
68 ~CriticalAntiDepBreaker();
70 /// Start - Initialize anti-dep breaking for a new basic block.
71 void StartBlock(MachineBasicBlock *BB);
73 /// BreakAntiDependencies - Identifiy anti-dependencies along the critical
75 /// of the ScheduleDAG and break them by renaming registers.
77 unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits,
78 MachineBasicBlock::iterator Begin,
79 MachineBasicBlock::iterator End,
80 unsigned InsertPosIndex);
82 /// Observe - Update liveness information to account for the current
83 /// instruction, which will not be scheduled.
85 void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex);
87 /// Finish - Finish anti-dep breaking for a basic block.
91 void PrescanInstruction(MachineInstr *MI);
92 void ScanInstruction(MachineInstr *MI, unsigned Count);
93 unsigned findSuitableFreeRegister(MachineInstr *MI,
96 const TargetRegisterClass *);