1 //=- llvm/CodeGen/AntiDepBreaker.h - Anti-Dependence Breaking -*- 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 AntiDepBreaker class, which implements
11 // anti-dependence breaking heuristics for post-register-allocation scheduling.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_ANTIDEPBREAKER_H
16 #define LLVM_CODEGEN_ANTIDEPBREAKER_H
18 #include "llvm/CodeGen/MachineBasicBlock.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineRegisterInfo.h"
22 #include "llvm/CodeGen/ScheduleDAG.h"
23 #include "llvm/Target/TargetRegisterInfo.h"
24 #include "llvm/ADT/SmallSet.h"
25 #include "llvm/ADT/SmallVector.h"
30 /// AntiDepBreaker - This class works into conjunction with the
31 /// post-RA scheduler to rename registers to break register
32 /// anti-dependencies.
33 class AntiDepBreaker {
35 typedef SmallSet<unsigned, 4> AntiDepRegSet;
36 typedef SmallVector<unsigned, 4> AntiDepRegVector;
37 typedef std::map<SUnit *, AntiDepRegVector> CandidateMap;
39 virtual ~AntiDepBreaker();
41 /// GetMaxTrials - Return the maximum number of anti-dependence
42 /// breaking attempts that will be made for a block.
43 virtual unsigned GetMaxTrials() =0;
45 /// NeedCandidates - Return true if the schedule must provide
46 /// candidates with BreakAntiDependencies().
47 virtual bool NeedCandidates() =0;
49 /// Start - Initialize anti-dep breaking for a new basic block.
50 virtual void StartBlock(MachineBasicBlock *BB) =0;
52 /// BreakAntiDependencies - Identifiy anti-dependencies within a
53 /// basic-block region and break them by renaming registers. Return
54 /// the number of anti-dependencies broken.
56 virtual unsigned BreakAntiDependencies(std::vector<SUnit>& SUnits,
57 CandidateMap& Candidates,
58 MachineBasicBlock::iterator& Begin,
59 MachineBasicBlock::iterator& End,
60 unsigned InsertPosIndex) =0;
62 /// Observe - Update liveness information to account for the current
63 /// instruction, which will not be scheduled.
65 virtual void Observe(MachineInstr *MI, unsigned Count,
66 unsigned InsertPosIndex) =0;
68 /// Finish - Finish anti-dep breaking for a basic block.
69 virtual void FinishBlock() =0;