AntiDepBreaker.h revision 223017 
1//=- llvm/CodeGen/AntiDepBreaker.h - Anti-Dependence Breaking -*- 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 AntiDepBreaker class, which implements
11// anti-dependence breaking heuristics for post-register-allocation scheduling.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_CODEGEN_ANTIDEPBREAKER_H
16#define LLVM_CODEGEN_ANTIDEPBREAKER_H
17
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 <vector>
25
26namespace llvm {
27
28/// AntiDepBreaker - This class works into conjunction with the
29/// post-RA scheduler to rename registers to break register
30/// anti-dependencies.
31class AntiDepBreaker {
32public:
33  typedef std::vector<std::pair<MachineInstr *, MachineInstr *> >
34    DbgValueVector;
35
36  virtual ~AntiDepBreaker();
37
38  /// Start - Initialize anti-dep breaking for a new basic block.
39  virtual void StartBlock(MachineBasicBlock *BB) =0;
40
41  /// BreakAntiDependencies - Identifiy anti-dependencies within a
42  /// basic-block region and break them by renaming registers. Return
43  /// the number of anti-dependencies broken.
44  ///
45  virtual unsigned BreakAntiDependencies(const std::vector<SUnit>& SUnits,
46                                         MachineBasicBlock::iterator Begin,
47                                         MachineBasicBlock::iterator End,
48                                         unsigned InsertPosIndex,
49                                         DbgValueVector &DbgValues) = 0;
50
51  /// Observe - Update liveness information to account for the current
52  /// instruction, which will not be scheduled.
53  ///
54  virtual void Observe(MachineInstr *MI, unsigned Count,
55                       unsigned InsertPosIndex) =0;
56
57  /// Finish - Finish anti-dep breaking for a basic block.
58  virtual void FinishBlock() =0;
59
60  /// UpdateDbgValue - Update DBG_VALUE if dependency breaker is updating
61  /// other machine instruction to use NewReg.
62  void UpdateDbgValue(MachineInstr *MI, unsigned OldReg, unsigned NewReg) {
63    assert (MI->isDebugValue() && "MI is not DBG_VALUE!");
64    if (MI && MI->getOperand(0).isReg() && MI->getOperand(0).getReg() == OldReg)
65      MI->getOperand(0).setReg(NewReg);
66  }
67};
68
69}
70
71#endif
72