1 //===- llvm/CodeGen/TailDuplicator.h ----------------------------*- 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 defines the TailDuplicator class. Used by the
11 // TailDuplication pass, and MachineBlockPlacement.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_TAILDUPLICATOR_H
16 #define LLVM_CODEGEN_TAILDUPLICATOR_H
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/ADT/SetVector.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/CodeGen/RegisterScavenging.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Target/TargetInstrInfo.h"
26 #include "llvm/Target/TargetSubtargetInfo.h"
32 class MachineBasicBlock;
33 class MachineBranchProbabilityInfo;
34 class MachineFunction;
36 class MachineModuleInfo;
37 class MachineRegisterInfo;
38 class TargetRegisterInfo;
40 /// Utility class to perform tail duplication.
41 class TailDuplicator {
42 const TargetInstrInfo *TII;
43 const TargetRegisterInfo *TRI;
44 const MachineBranchProbabilityInfo *MBPI;
45 const MachineModuleInfo *MMI;
46 MachineRegisterInfo *MRI;
52 // A list of virtual registers for which to update SSA form.
53 SmallVector<unsigned, 16> SSAUpdateVRs;
55 // For each virtual register in SSAUpdateVals keep a list of source virtual
57 using AvailableValsTy = std::vector<std::pair<MachineBasicBlock *, unsigned>>;
59 DenseMap<unsigned, AvailableValsTy> SSAUpdateVals;
62 /// Prepare to run on a specific machine function.
63 /// @param MF - Function that will be processed
64 /// @param MBPI - Branch Probability Info. Used to propagate correct
65 /// probabilities when modifying the CFG.
66 /// @param LayoutMode - When true, don't use the existing layout to make
68 /// @param TailDupSize - Maxmimum size of blocks to tail-duplicate. Zero
69 /// default implies using the command line value TailDupSize.
70 void initMF(MachineFunction &MF,
71 const MachineBranchProbabilityInfo *MBPI,
72 bool LayoutMode, unsigned TailDupSize = 0);
74 bool tailDuplicateBlocks();
75 static bool isSimpleBB(MachineBasicBlock *TailBB);
76 bool shouldTailDuplicate(bool IsSimple, MachineBasicBlock &TailBB);
78 /// Returns true if TailBB can successfully be duplicated into PredBB
79 bool canTailDuplicate(MachineBasicBlock *TailBB, MachineBasicBlock *PredBB);
81 /// Tail duplicate a single basic block into its predecessors, and then clean
83 /// If \p DuplicatePreds is not null, it will be updated to contain the list
84 /// of predecessors that received a copy of \p MBB.
85 /// If \p RemovalCallback is non-null. It will be called before MBB is
87 bool tailDuplicateAndUpdate(
88 bool IsSimple, MachineBasicBlock *MBB,
89 MachineBasicBlock *ForcedLayoutPred,
90 SmallVectorImpl<MachineBasicBlock*> *DuplicatedPreds = nullptr,
91 function_ref<void(MachineBasicBlock *)> *RemovalCallback = nullptr);
94 using RegSubRegPair = TargetInstrInfo::RegSubRegPair;
96 void addSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
97 MachineBasicBlock *BB);
98 void processPHI(MachineInstr *MI, MachineBasicBlock *TailBB,
99 MachineBasicBlock *PredBB,
100 DenseMap<unsigned, RegSubRegPair> &LocalVRMap,
101 SmallVectorImpl<std::pair<unsigned, RegSubRegPair>> &Copies,
102 const DenseSet<unsigned> &UsedByPhi, bool Remove);
103 void duplicateInstruction(MachineInstr *MI, MachineBasicBlock *TailBB,
104 MachineBasicBlock *PredBB,
105 DenseMap<unsigned, RegSubRegPair> &LocalVRMap,
106 const DenseSet<unsigned> &UsedByPhi);
107 void updateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
108 SmallVectorImpl<MachineBasicBlock *> &TDBBs,
109 SmallSetVector<MachineBasicBlock *, 8> &Succs);
110 bool canCompletelyDuplicateBB(MachineBasicBlock &BB);
111 bool duplicateSimpleBB(MachineBasicBlock *TailBB,
112 SmallVectorImpl<MachineBasicBlock *> &TDBBs,
113 const DenseSet<unsigned> &RegsUsedByPhi,
114 SmallVectorImpl<MachineInstr *> &Copies);
115 bool tailDuplicate(bool IsSimple,
116 MachineBasicBlock *TailBB,
117 MachineBasicBlock *ForcedLayoutPred,
118 SmallVectorImpl<MachineBasicBlock *> &TDBBs,
119 SmallVectorImpl<MachineInstr *> &Copies);
120 void appendCopies(MachineBasicBlock *MBB,
121 SmallVectorImpl<std::pair<unsigned,RegSubRegPair>> &CopyInfos,
122 SmallVectorImpl<MachineInstr *> &Copies);
124 void removeDeadBlock(
125 MachineBasicBlock *MBB,
126 function_ref<void(MachineBasicBlock *)> *RemovalCallback = nullptr);
129 } // end namespace llvm
131 #endif // LLVM_CODEGEN_TAILDUPLICATOR_H