| //===- 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 function, the basic blocks the make up the |
| // loop, the nesting depth of the loop, and the successor blocks of the loop. |
| // |
| // It can calculate on the fly a variety of different bits of information, such |
| // as whether there is a preheader for the loop, the number of back edges to the |
| // header, and whether or not a particular block branches out of the loop. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ANALYSIS_LOOP_INFO_H |
| #define LLVM_ANALYSIS_LOOP_INFO_H |
| |
| #include "llvm/Pass.h" |
| #include "Support/GraphTraits.h" |
| #include <set> |
| |
| class DominatorSet; |
| class LoopInfo; |
| |
| //===----------------------------------------------------------------------===// |
| /// 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 |
| std::vector<BasicBlock*> ExitBlocks; // Reachable blocks outside the loop |
| unsigned LoopDepth; // Nesting depth of this loop |
| |
| Loop(const Loop &); // DO NOT IMPLEMENT |
| const Loop &operator=(const Loop &); // DO NOT IMPLEMENT |
| public: |
| |
| unsigned getLoopDepth() const { return LoopDepth; } |
| 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; |
| |
| /// getSubLoops - Return the loops contained entirely within this loop |
| /// |
| const std::vector<Loop*> &getSubLoops() const { return SubLoops; } |
| |
| /// getBlocks - Get a list of the basic blocks which make up this loop. |
| /// |
| const std::vector<BasicBlock*> &getBlocks() const { return Blocks; } |
| |
| /// getExitBlocks - Return all of the successor blocks of this loop. These |
| /// are the blocks _outside of the current loop_ which are branched to. |
| /// |
| const std::vector<BasicBlock*> &getExitBlocks() const { return ExitBlocks; } |
| |
| /// isLoopExit - True if terminator in the block can branch to another block |
| /// that is outside of the current loop. The reached block should be in the |
| /// ExitBlocks list. |
| /// |
| bool isLoopExit(const BasicBlock *BB) const; |
| |
| /// getNumBackEdges - Calculate the number of back edges to the loop header |
| /// |
| unsigned getNumBackEdges() const; |
| |
| /// hasExitBlock - Return true if the current loop has the specified block as |
| /// an exit block... |
| bool hasExitBlock(BasicBlock *BB) const { |
| for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) |
| if (ExitBlocks[i] == BB) |
| return true; |
| return false; |
| } |
| |
| /// 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. The "preheaders" pass can be |
| /// "Required" to ensure that there is always a preheader node for every loop. |
| /// |
| /// This method returns null if there is no preheader for the loop (either |
| /// because the loop is dead or because multiple blocks branch to the header |
| /// node of this loop). |
| /// |
| BasicBlock *getLoopPreheader() const; |
| |
| /// 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); |
| |
| /// changeExitBlock - This method is used to update loop information. All |
| /// instances of the specified Old basic block are removed from the exit list |
| /// and replaced with New. |
| /// |
| void changeExitBlock(BasicBlock *Old, BasicBlock *New); |
| |
| void print(std::ostream &O, unsigned Depth = 0) const; |
| void dump() const; |
| private: |
| friend class LoopInfo; |
| inline Loop(BasicBlock *BB) : ParentLoop(0) { |
| Blocks.push_back(BB); LoopDepth = 0; |
| } |
| ~Loop() { |
| for (unsigned i = 0, e = SubLoops.size(); i != e; ++i) |
| delete SubLoops[i]; |
| } |
| |
| void setLoopDepth(unsigned Level) { |
| LoopDepth = Level; |
| for (unsigned i = 0, e = SubLoops.size(); i != e; ++i) |
| SubLoops[i]->setLoopDepth(Level+1); |
| } |
| }; |
| |
| |
| |
| //===----------------------------------------------------------------------===// |
| /// 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(); } |
| |
| const std::vector<Loop*> &getTopLevelLoops() const { return TopLevelLoops; } |
| |
| /// 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. |
| /// |
| const Loop *getLoopFor(const BasicBlock *BB) const { |
| std::map<BasicBlock *, Loop*>::const_iterator I=BBMap.find((BasicBlock*)BB); |
| return I != BBMap.end() ? I->second : 0; |
| } |
| |
| /// operator[] - same as getLoopFor... |
| /// |
| inline 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 { |
| return getLoopFor(BB)->getHeader() == BB; |
| } |
| |
| /// runOnFunction - Calculate the natural loop information. |
| /// |
| virtual bool runOnFunction(Function &F); |
| |
| virtual void releaseMemory(); |
| void print(std::ostream &O) const; |
| |
| /// getAnalysisUsage - Requires dominator sets |
| /// |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const; |
| |
| 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->getSubLoops().begin(); |
| } |
| static inline ChildIteratorType child_end(NodeType *N) { |
| return N->getSubLoops().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->getSubLoops().begin(); |
| } |
| static inline ChildIteratorType child_end(NodeType *N) { |
| return N->getSubLoops().end(); |
| } |
| }; |
| |
| #endif |