John Bauman | 8940182 | 2014-05-06 15:04:28 -0400 | [diff] [blame] | 1 | //===- llvm/CodeGen/MachineLoopInfo.h - Natural Loop Calculator -*- 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 defines the MachineLoopInfo class that is used to identify natural |
| 11 | // loops and determine the loop depth of various nodes of the CFG. Note that |
| 12 | // natural loops may actually be several loops that share the same header node. |
| 13 | // |
| 14 | // This analysis calculates the nesting structure of loops in a function. For |
| 15 | // each natural loop identified, this analysis identifies natural loops |
| 16 | // contained entirely within the loop and the basic blocks the make up the loop. |
| 17 | // |
| 18 | // It can calculate on the fly various bits of information, for example: |
| 19 | // |
| 20 | // * whether there is a preheader for the loop |
| 21 | // * the number of back edges to the header |
| 22 | // * whether or not a particular block branches out of the loop |
| 23 | // * the successor blocks of the loop |
| 24 | // * the loop depth |
| 25 | // * the trip count |
| 26 | // * etc... |
| 27 | // |
| 28 | //===----------------------------------------------------------------------===// |
| 29 | |
| 30 | #ifndef LLVM_CODEGEN_MACHINE_LOOP_INFO_H |
| 31 | #define LLVM_CODEGEN_MACHINE_LOOP_INFO_H |
| 32 | |
| 33 | #include "llvm/CodeGen/MachineFunctionPass.h" |
| 34 | #include "llvm/Analysis/LoopInfo.h" |
| 35 | |
| 36 | namespace llvm { |
| 37 | |
| 38 | class MachineLoop : public LoopBase<MachineBasicBlock, MachineLoop> { |
| 39 | public: |
| 40 | MachineLoop(); |
| 41 | |
| 42 | /// getTopBlock - Return the "top" block in the loop, which is the first |
| 43 | /// block in the linear layout, ignoring any parts of the loop not |
| 44 | /// contiguous with the part the contains the header. |
| 45 | MachineBasicBlock *getTopBlock(); |
| 46 | |
| 47 | /// getBottomBlock - Return the "bottom" block in the loop, which is the last |
| 48 | /// block in the linear layout, ignoring any parts of the loop not |
| 49 | /// contiguous with the part the contains the header. |
| 50 | MachineBasicBlock *getBottomBlock(); |
| 51 | |
| 52 | void dump() const; |
| 53 | |
| 54 | private: |
| 55 | friend class LoopInfoBase<MachineBasicBlock, MachineLoop>; |
| 56 | explicit MachineLoop(MachineBasicBlock *MBB) |
| 57 | : LoopBase<MachineBasicBlock, MachineLoop>(MBB) {} |
| 58 | }; |
| 59 | |
| 60 | class MachineLoopInfo : public MachineFunctionPass { |
| 61 | LoopInfoBase<MachineBasicBlock, MachineLoop> LI; |
| 62 | friend class LoopBase<MachineBasicBlock, MachineLoop>; |
| 63 | |
| 64 | void operator=(const MachineLoopInfo &); // do not implement |
| 65 | MachineLoopInfo(const MachineLoopInfo &); // do not implement |
| 66 | |
| 67 | public: |
| 68 | static char ID; // Pass identification, replacement for typeid |
| 69 | |
John Bauman | 19bac1e | 2014-05-06 15:23:49 -0400 | [diff] [blame] | 70 | MachineLoopInfo() : MachineFunctionPass(ID) { |
| 71 | initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry()); |
| 72 | } |
John Bauman | 8940182 | 2014-05-06 15:04:28 -0400 | [diff] [blame] | 73 | |
| 74 | LoopInfoBase<MachineBasicBlock, MachineLoop>& getBase() { return LI; } |
| 75 | |
| 76 | /// iterator/begin/end - The interface to the top-level loops in the current |
| 77 | /// function. |
| 78 | /// |
| 79 | typedef LoopInfoBase<MachineBasicBlock, MachineLoop>::iterator iterator; |
| 80 | inline iterator begin() const { return LI.begin(); } |
| 81 | inline iterator end() const { return LI.end(); } |
| 82 | bool empty() const { return LI.empty(); } |
| 83 | |
| 84 | /// getLoopFor - Return the inner most loop that BB lives in. If a basic |
| 85 | /// block is in no loop (for example the entry node), null is returned. |
| 86 | /// |
| 87 | inline MachineLoop *getLoopFor(const MachineBasicBlock *BB) const { |
| 88 | return LI.getLoopFor(BB); |
| 89 | } |
| 90 | |
| 91 | /// operator[] - same as getLoopFor... |
| 92 | /// |
| 93 | inline const MachineLoop *operator[](const MachineBasicBlock *BB) const { |
| 94 | return LI.getLoopFor(BB); |
| 95 | } |
| 96 | |
| 97 | /// getLoopDepth - Return the loop nesting level of the specified block... |
| 98 | /// |
| 99 | inline unsigned getLoopDepth(const MachineBasicBlock *BB) const { |
| 100 | return LI.getLoopDepth(BB); |
| 101 | } |
| 102 | |
| 103 | // isLoopHeader - True if the block is a loop header node |
| 104 | inline bool isLoopHeader(MachineBasicBlock *BB) const { |
| 105 | return LI.isLoopHeader(BB); |
| 106 | } |
| 107 | |
| 108 | /// runOnFunction - Calculate the natural loop information. |
| 109 | /// |
| 110 | virtual bool runOnMachineFunction(MachineFunction &F); |
| 111 | |
| 112 | virtual void releaseMemory() { LI.releaseMemory(); } |
| 113 | |
| 114 | virtual void getAnalysisUsage(AnalysisUsage &AU) const; |
| 115 | |
| 116 | /// removeLoop - This removes the specified top-level loop from this loop info |
| 117 | /// object. The loop is not deleted, as it will presumably be inserted into |
| 118 | /// another loop. |
| 119 | inline MachineLoop *removeLoop(iterator I) { return LI.removeLoop(I); } |
| 120 | |
| 121 | /// changeLoopFor - Change the top-level loop that contains BB to the |
| 122 | /// specified loop. This should be used by transformations that restructure |
| 123 | /// the loop hierarchy tree. |
| 124 | inline void changeLoopFor(MachineBasicBlock *BB, MachineLoop *L) { |
| 125 | LI.changeLoopFor(BB, L); |
| 126 | } |
| 127 | |
| 128 | /// changeTopLevelLoop - Replace the specified loop in the top-level loops |
| 129 | /// list with the indicated loop. |
| 130 | inline void changeTopLevelLoop(MachineLoop *OldLoop, MachineLoop *NewLoop) { |
| 131 | LI.changeTopLevelLoop(OldLoop, NewLoop); |
| 132 | } |
| 133 | |
| 134 | /// addTopLevelLoop - This adds the specified loop to the collection of |
| 135 | /// top-level loops. |
| 136 | inline void addTopLevelLoop(MachineLoop *New) { |
| 137 | LI.addTopLevelLoop(New); |
| 138 | } |
| 139 | |
| 140 | /// removeBlock - This method completely removes BB from all data structures, |
| 141 | /// including all of the Loop objects it is nested in and our mapping from |
| 142 | /// MachineBasicBlocks to loops. |
| 143 | void removeBlock(MachineBasicBlock *BB) { |
| 144 | LI.removeBlock(BB); |
| 145 | } |
| 146 | }; |
| 147 | |
| 148 | |
| 149 | // Allow clients to walk the list of nested loops... |
| 150 | template <> struct GraphTraits<const MachineLoop*> { |
| 151 | typedef const MachineLoop NodeType; |
| 152 | typedef MachineLoopInfo::iterator ChildIteratorType; |
| 153 | |
| 154 | static NodeType *getEntryNode(const MachineLoop *L) { return L; } |
| 155 | static inline ChildIteratorType child_begin(NodeType *N) { |
| 156 | return N->begin(); |
| 157 | } |
| 158 | static inline ChildIteratorType child_end(NodeType *N) { |
| 159 | return N->end(); |
| 160 | } |
| 161 | }; |
| 162 | |
| 163 | template <> struct GraphTraits<MachineLoop*> { |
| 164 | typedef MachineLoop NodeType; |
| 165 | typedef MachineLoopInfo::iterator ChildIteratorType; |
| 166 | |
| 167 | static NodeType *getEntryNode(MachineLoop *L) { return L; } |
| 168 | static inline ChildIteratorType child_begin(NodeType *N) { |
| 169 | return N->begin(); |
| 170 | } |
| 171 | static inline ChildIteratorType child_end(NodeType *N) { |
| 172 | return N->end(); |
| 173 | } |
| 174 | }; |
| 175 | |
| 176 | } // End llvm namespace |
| 177 | |
| 178 | #endif |