| //===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines the LoopInfo class that is used to identify natural loops |
| // and determine the loop depth of various nodes of the CFG. Note that natural |
| // loops may actually be several loops that share the same header node. |
| // |
| // This analysis calculates the nesting structure of loops in a function. For |
| // each natural loop identified, this analysis identifies natural loops |
| // contained entirely within the loop and the basic blocks the make up the loop. |
| // |
| // It can calculate on the fly various bits of information, for example: |
| // |
| // * whether there is a preheader for the loop |
| // * the number of back edges to the header |
| // * whether or not a particular block branches out of the loop |
| // * the successor blocks of the loop |
| // * the loop depth |
| // * the trip count |
| // * etc... |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ANALYSIS_LOOP_INFO_H |
| #define LLVM_ANALYSIS_LOOP_INFO_H |
| |
| #include "llvm/Pass.h" |
| #include "llvm/ADT/GraphTraits.h" |
| |
| namespace llvm { |
| |
| struct DominatorSet; |
| class LoopInfo; |
| class PHINode; |
| class Instruction; |
| |
| //===----------------------------------------------------------------------===// |
| /// Loop class - Instances of this class are used to represent loops that are |
| /// detected in the flow graph |
| /// |
| class Loop { |
| Loop *ParentLoop; |
| std::vector<Loop*> SubLoops; // Loops contained entirely within this one |
| std::vector<BasicBlock*> Blocks; // First entry is the header node |
| |
| Loop(const Loop &); // DO NOT IMPLEMENT |
| const Loop &operator=(const Loop &); // DO NOT IMPLEMENT |
| public: |
| /// Loop ctor - This creates an empty loop. |
| Loop() : ParentLoop(0) {} |
| ~Loop() { |
| for (unsigned i = 0, e = SubLoops.size(); i != e; ++i) |
| delete SubLoops[i]; |
| } |
| |
| unsigned getLoopDepth() const { |
| unsigned D = 0; |
| for (const Loop *CurLoop = this; CurLoop; CurLoop = CurLoop->ParentLoop) |
| ++D; |
| return D; |
| } |
| BasicBlock *getHeader() const { return Blocks.front(); } |
| Loop *getParentLoop() const { return ParentLoop; } |
| |
| /// contains - Return true of the specified basic block is in this loop |
| /// |
| bool contains(const BasicBlock *BB) const; |
| |
| /// iterator/begin/end - Return the loops contained entirely within this loop. |
| /// |
| const std::vector<Loop*> &getSubLoops() const { return SubLoops; } |
| typedef std::vector<Loop*>::const_iterator iterator; |
| iterator begin() const { return SubLoops.begin(); } |
| iterator end() const { return SubLoops.end(); } |
| |
| /// getBlocks - Get a list of the basic blocks which make up this loop. |
| /// |
| const std::vector<BasicBlock*> &getBlocks() const { return Blocks; } |
| typedef std::vector<BasicBlock*>::const_iterator block_iterator; |
| block_iterator block_begin() const { return Blocks.begin(); } |
| block_iterator block_end() const { return Blocks.end(); } |
| |
| /// isLoopExit - True if terminator in the block can branch to another block |
| /// that is outside of the current loop. |
| /// |
| bool isLoopExit(const BasicBlock *BB) const; |
| |
| /// getNumBackEdges - Calculate the number of back edges to the loop header |
| /// |
| unsigned getNumBackEdges() const; |
| |
| /// isLoopInvariant - Return true if the specified value is loop invariant |
| /// |
| bool isLoopInvariant(Value *V) const; |
| |
| //===--------------------------------------------------------------------===// |
| // APIs for simple analysis of the loop. |
| // |
| // Note that all of these methods can fail on general loops (ie, there may not |
| // be a preheader, etc). For best success, the loop simplification and |
| // induction variable canonicalization pass should be used to normalize loops |
| // for easy analysis. These methods assume canonical loops. |
| |
| /// getExitBlocks - Return all of the successor blocks of this loop. These |
| /// are the blocks _outside of the current loop_ which are branched to. |
| /// |
| void getExitBlocks(std::vector<BasicBlock*> &Blocks) const; |
| |
| /// getLoopPreheader - If there is a preheader for this loop, return it. A |
| /// loop has a preheader if there is only one edge to the header of the loop |
| /// from outside of the loop. If this is the case, the block branching to the |
| /// header of the loop is the preheader node. |
| /// |
| /// This method returns null if there is no preheader for the loop. |
| /// |
| BasicBlock *getLoopPreheader() const; |
| |
| /// getLoopLatch - If there is a latch block for this loop, return it. A |
| /// latch block is the canonical backedge for a loop. A loop header in normal |
| /// form has two edges into it: one from a preheader and one from a latch |
| /// block. |
| BasicBlock *getLoopLatch() const; |
| |
| /// getCanonicalInductionVariable - Check to see if the loop has a canonical |
| /// induction variable: an integer recurrence that starts at 0 and increments |
| /// by one each time through the loop. If so, return the phi node that |
| /// corresponds to it. |
| /// |
| PHINode *getCanonicalInductionVariable() const; |
| |
| /// getCanonicalInductionVariableIncrement - Return the LLVM value that holds |
| /// the canonical induction variable value for the "next" iteration of the |
| /// loop. This always succeeds if getCanonicalInductionVariable succeeds. |
| /// |
| Instruction *getCanonicalInductionVariableIncrement() const; |
| |
| /// getTripCount - Return a loop-invariant LLVM value indicating the number of |
| /// times the loop will be executed. Note that this means that the backedge |
| /// of the loop executes N-1 times. If the trip-count cannot be determined, |
| /// this returns null. |
| /// |
| Value *getTripCount() const; |
| |
| //===--------------------------------------------------------------------===// |
| // APIs for updating loop information after changing the CFG |
| // |
| |
| /// addBasicBlockToLoop - This method is used by other analyses to update loop |
| /// information. NewBB is set to be a new member of the current loop. |
| /// Because of this, it is added as a member of all parent loops, and is added |
| /// to the specified LoopInfo object as being in the current basic block. It |
| /// is not valid to replace the loop header with this method. |
| /// |
| void addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI); |
| |
| /// replaceChildLoopWith - This is used when splitting loops up. It replaces |
| /// the OldChild entry in our children list with NewChild, and updates the |
| /// parent pointer of OldChild to be null and the NewChild to be this loop. |
| /// This updates the loop depth of the new child. |
| void replaceChildLoopWith(Loop *OldChild, Loop *NewChild); |
| |
| /// addChildLoop - Add the specified loop to be a child of this loop. This |
| /// updates the loop depth of the new child. |
| /// |
| void addChildLoop(Loop *NewChild); |
| |
| /// removeChildLoop - This removes the specified child from being a subloop of |
| /// this loop. The loop is not deleted, as it will presumably be inserted |
| /// into another loop. |
| Loop *removeChildLoop(iterator OldChild); |
| |
| /// addBlockEntry - This adds a basic block directly to the basic block list. |
| /// This should only be used by transformations that create new loops. Other |
| /// transformations should use addBasicBlockToLoop. |
| void addBlockEntry(BasicBlock *BB) { |
| Blocks.push_back(BB); |
| } |
| |
| /// moveToHeader - This method is used to move BB (which must be part of this |
| /// loop) to be the loop header of the loop (the block that dominates all |
| /// others). |
| void moveToHeader(BasicBlock *BB) { |
| if (Blocks[0] == BB) return; |
| for (unsigned i = 0; ; ++i) { |
| assert(i != Blocks.size() && "Loop does not contain BB!"); |
| if (Blocks[i] == BB) { |
| Blocks[i] = Blocks[0]; |
| Blocks[0] = BB; |
| return; |
| } |
| } |
| } |
| |
| /// removeBlockFromLoop - This removes the specified basic block from the |
| /// current loop, updating the Blocks as appropriate. This does not update |
| /// the mapping in the LoopInfo class. |
| void removeBlockFromLoop(BasicBlock *BB); |
| |
| void print(std::ostream &O, unsigned Depth = 0) const; |
| void dump() const; |
| private: |
| friend class LoopInfo; |
| Loop(BasicBlock *BB) : ParentLoop(0) { |
| Blocks.push_back(BB); |
| } |
| }; |
| |
| |
| |
| //===----------------------------------------------------------------------===// |
| /// LoopInfo - This class builds and contains all of the top level loop |
| /// structures in the specified function. |
| /// |
| class LoopInfo : public FunctionPass { |
| // BBMap - Mapping of basic blocks to the inner most loop they occur in |
| std::map<BasicBlock*, Loop*> BBMap; |
| std::vector<Loop*> TopLevelLoops; |
| friend class Loop; |
| public: |
| ~LoopInfo() { releaseMemory(); } |
| |
| /// iterator/begin/end - The interface to the top-level loops in the current |
| /// function. |
| /// |
| typedef std::vector<Loop*>::const_iterator iterator; |
| iterator begin() const { return TopLevelLoops.begin(); } |
| iterator end() const { return TopLevelLoops.end(); } |
| |
| /// getLoopFor - Return the inner most loop that BB lives in. If a basic |
| /// block is in no loop (for example the entry node), null is returned. |
| /// |
| Loop *getLoopFor(const BasicBlock *BB) const { |
| std::map<BasicBlock *, Loop*>::const_iterator I= |
| BBMap.find(const_cast<BasicBlock*>(BB)); |
| return I != BBMap.end() ? I->second : 0; |
| } |
| |
| /// operator[] - same as getLoopFor... |
| /// |
| const Loop *operator[](const BasicBlock *BB) const { |
| return getLoopFor(BB); |
| } |
| |
| /// getLoopDepth - Return the loop nesting level of the specified block... |
| /// |
| unsigned getLoopDepth(const BasicBlock *BB) const { |
| const Loop *L = getLoopFor(BB); |
| return L ? L->getLoopDepth() : 0; |
| } |
| |
| // isLoopHeader - True if the block is a loop header node |
| bool isLoopHeader(BasicBlock *BB) const { |
| const Loop *L = getLoopFor(BB); |
| return L && L->getHeader() == BB; |
| } |
| |
| /// runOnFunction - Calculate the natural loop information. |
| /// |
| virtual bool runOnFunction(Function &F); |
| |
| virtual void releaseMemory(); |
| void print(std::ostream &O, const Module* = 0) const; |
| |
| /// getAnalysisUsage - Requires dominator sets |
| /// |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const; |
| |
| /// removeLoop - This removes the specified top-level loop from this loop info |
| /// object. The loop is not deleted, as it will presumably be inserted into |
| /// another loop. |
| Loop *removeLoop(iterator I); |
| |
| /// changeLoopFor - Change the top-level loop that contains BB to the |
| /// specified loop. This should be used by transformations that restructure |
| /// the loop hierarchy tree. |
| void changeLoopFor(BasicBlock *BB, Loop *L); |
| |
| /// changeTopLevelLoop - Replace the specified loop in the top-level loops |
| /// list with the indicated loop. |
| void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop); |
| |
| /// addTopLevelLoop - This adds the specified loop to the collection of |
| /// top-level loops. |
| void addTopLevelLoop(Loop *New) { |
| assert(New->getParentLoop() == 0 && "Loop already in subloop!"); |
| TopLevelLoops.push_back(New); |
| } |
| |
| /// removeBlock - This method completely removes BB from all data structures, |
| /// including all of the Loop objects it is nested in and our mapping from |
| /// BasicBlocks to loops. |
| void removeBlock(BasicBlock *BB); |
| |
| static void stub(); // Noop |
| private: |
| void Calculate(const DominatorSet &DS); |
| Loop *ConsiderForLoop(BasicBlock *BB, const DominatorSet &DS); |
| void MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent); |
| void InsertLoopInto(Loop *L, Loop *Parent); |
| }; |
| |
| |
| // Make sure that any clients of this file link in LoopInfo.cpp |
| static IncludeFile |
| LOOP_INFO_INCLUDE_FILE((void*)(&LoopInfo::stub)); |
| |
| // Allow clients to walk the list of nested loops... |
| template <> struct GraphTraits<const Loop*> { |
| typedef const Loop NodeType; |
| typedef std::vector<Loop*>::const_iterator ChildIteratorType; |
| |
| static NodeType *getEntryNode(const Loop *L) { return L; } |
| static inline ChildIteratorType child_begin(NodeType *N) { |
| return N->begin(); |
| } |
| static inline ChildIteratorType child_end(NodeType *N) { |
| return N->end(); |
| } |
| }; |
| |
| template <> struct GraphTraits<Loop*> { |
| typedef Loop NodeType; |
| typedef std::vector<Loop*>::const_iterator ChildIteratorType; |
| |
| static NodeType *getEntryNode(Loop *L) { return L; } |
| static inline ChildIteratorType child_begin(NodeType *N) { |
| return N->begin(); |
| } |
| static inline ChildIteratorType child_end(NodeType *N) { |
| return N->end(); |
| } |
| }; |
| |
| } // End llvm namespace |
| |
| #endif |