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/STLExtras.h"
19 #include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
20 #include "llvm/CodeGen/MachineModuleInfo.h"
21 #include "llvm/CodeGen/MachineRegisterInfo.h"
22 #include "llvm/CodeGen/MachineSSAUpdater.h"
23 #include "llvm/CodeGen/RegisterScavenging.h"
24 #include "llvm/Target/TargetInstrInfo.h"
25 #include "llvm/Target/TargetRegisterInfo.h"
26 #include "llvm/Target/TargetSubtargetInfo.h"
30 extern cl::opt<unsigned> TailDupIndirectBranchSize;
32 /// Utility class to perform tail duplication.
33 class TailDuplicator {
34 const TargetInstrInfo *TII;
35 const TargetRegisterInfo *TRI;
36 const MachineBranchProbabilityInfo *MBPI;
37 const MachineModuleInfo *MMI;
38 MachineRegisterInfo *MRI;
44 // A list of virtual registers for which to update SSA form.
45 SmallVector<unsigned, 16> SSAUpdateVRs;
47 // For each virtual register in SSAUpdateVals keep a list of source virtual
49 typedef std::vector<std::pair<MachineBasicBlock *, unsigned>> AvailableValsTy;
51 DenseMap<unsigned, AvailableValsTy> SSAUpdateVals;
54 /// Prepare to run on a specific machine function.
55 /// @param MF - Function that will be processed
56 /// @param MBPI - Branch Probability Info. Used to propagate correct
57 /// probabilities when modifying the CFG.
58 /// @param LayoutMode - When true, don't use the existing layout to make
60 /// @param TailDupSize - Maxmimum size of blocks to tail-duplicate. Zero
61 /// default implies using the command line value TailDupSize.
62 void initMF(MachineFunction &MF,
63 const MachineBranchProbabilityInfo *MBPI,
64 bool LayoutMode, unsigned TailDupSize = 0);
65 bool tailDuplicateBlocks();
66 static bool isSimpleBB(MachineBasicBlock *TailBB);
67 bool shouldTailDuplicate(bool IsSimple, MachineBasicBlock &TailBB);
68 /// Returns true if TailBB can successfully be duplicated into PredBB
69 bool canTailDuplicate(MachineBasicBlock *TailBB, MachineBasicBlock *PredBB);
70 /// Tail duplicate a single basic block into its predecessors, and then clean
72 /// If \p DuplicatePreds is not null, it will be updated to contain the list
73 /// of predecessors that received a copy of \p MBB.
74 /// If \p RemovalCallback is non-null. It will be called before MBB is
76 bool tailDuplicateAndUpdate(
77 bool IsSimple, MachineBasicBlock *MBB,
78 MachineBasicBlock *ForcedLayoutPred,
79 SmallVectorImpl<MachineBasicBlock*> *DuplicatedPreds = nullptr,
80 llvm::function_ref<void(MachineBasicBlock *)> *RemovalCallback = nullptr);
83 typedef TargetInstrInfo::RegSubRegPair RegSubRegPair;
85 void addSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
86 MachineBasicBlock *BB);
87 void processPHI(MachineInstr *MI, MachineBasicBlock *TailBB,
88 MachineBasicBlock *PredBB,
89 DenseMap<unsigned, RegSubRegPair> &LocalVRMap,
90 SmallVectorImpl<std::pair<unsigned, RegSubRegPair>> &Copies,
91 const DenseSet<unsigned> &UsedByPhi, bool Remove);
92 void duplicateInstruction(MachineInstr *MI, MachineBasicBlock *TailBB,
93 MachineBasicBlock *PredBB,
94 DenseMap<unsigned, RegSubRegPair> &LocalVRMap,
95 const DenseSet<unsigned> &UsedByPhi);
96 void updateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
97 SmallVectorImpl<MachineBasicBlock *> &TDBBs,
98 SmallSetVector<MachineBasicBlock *, 8> &Succs);
99 bool canCompletelyDuplicateBB(MachineBasicBlock &BB);
100 bool duplicateSimpleBB(MachineBasicBlock *TailBB,
101 SmallVectorImpl<MachineBasicBlock *> &TDBBs,
102 const DenseSet<unsigned> &RegsUsedByPhi,
103 SmallVectorImpl<MachineInstr *> &Copies);
104 bool tailDuplicate(bool IsSimple,
105 MachineBasicBlock *TailBB,
106 MachineBasicBlock *ForcedLayoutPred,
107 SmallVectorImpl<MachineBasicBlock *> &TDBBs,
108 SmallVectorImpl<MachineInstr *> &Copies);
109 void appendCopies(MachineBasicBlock *MBB,
110 SmallVectorImpl<std::pair<unsigned,RegSubRegPair>> &CopyInfos,
111 SmallVectorImpl<MachineInstr *> &Copies);
113 void removeDeadBlock(
114 MachineBasicBlock *MBB,
115 llvm::function_ref<void(MachineBasicBlock *)> *RemovalCallback = nullptr);
118 } // End llvm namespace