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/Target/TargetRegisterInfo.h"
26 #include "llvm/ADT/BitVector.h"
27 #include "llvm/ADT/SmallSet.h"
31 class CriticalAntiDepBreaker : public AntiDepBreaker {
33 MachineRegisterInfo &MRI;
34 const TargetRegisterInfo *TRI;
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;
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
46 const TargetRegisterClass *
47 Classes[TargetRegisterInfo::FirstVirtualRegister];
49 /// RegRegs - Map registers to all their references within a live range.
50 std::multimap<unsigned, MachineOperand *> RegRefs;
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];
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];
60 /// KeepRegs - A set of registers which are live and cannot be changed to
61 /// break anti-dependencies.
62 SmallSet<unsigned, 4> KeepRegs;
65 CriticalAntiDepBreaker(MachineFunction& MFi);
66 ~CriticalAntiDepBreaker();
68 /// Start - Initialize anti-dep breaking for a new basic block.
69 void StartBlock(MachineBasicBlock *BB);
71 /// BreakAntiDependencies - Identifiy anti-dependencies along the critical path
72 /// of the ScheduleDAG and break them by renaming registers.
74 unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
75 MachineBasicBlock::iterator& Begin,
76 MachineBasicBlock::iterator& End,
77 unsigned InsertPosIndex);
79 /// Observe - Update liveness information to account for the current
80 /// instruction, which will not be scheduled.
82 void Observe(MachineInstr *MI, unsigned Count, unsigned InsertPosIndex);
84 /// Finish - Finish anti-dep breaking for a basic block.
88 void PrescanInstruction(MachineInstr *MI);
89 void ScanInstruction(MachineInstr *MI, unsigned Count);
90 unsigned findSuitableFreeRegister(unsigned AntiDepReg,
92 const TargetRegisterClass *);