| //===- llvm/Analysis/LoopInfo.h - Natural Loop Calculator -------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file 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. A natural loop |
| // has exactly one entry-point, which is called the header. 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 |
| // * etc... |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_ANALYSIS_LOOPINFO_H |
| #define LLVM_ANALYSIS_LOOPINFO_H |
| |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/DenseSet.h" |
| #include "llvm/ADT/GraphTraits.h" |
| #include "llvm/ADT/SmallPtrSet.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/IR/CFG.h" |
| #include "llvm/IR/Instruction.h" |
| #include "llvm/Pass.h" |
| #include <algorithm> |
| |
| namespace llvm { |
| |
| template<typename T> |
| inline void RemoveFromVector(std::vector<T*> &V, T *N) { |
| typename std::vector<T*>::iterator I = std::find(V.begin(), V.end(), N); |
| assert(I != V.end() && "N is not in this list!"); |
| V.erase(I); |
| } |
| |
| class DominatorTree; |
| class LoopInfo; |
| class Loop; |
| class MDNode; |
| class PHINode; |
| class raw_ostream; |
| template<class N> class DominatorTreeBase; |
| template<class N, class M> class LoopInfoBase; |
| template<class N, class M> class LoopBase; |
| |
| //===----------------------------------------------------------------------===// |
| /// LoopBase class - Instances of this class are used to represent loops that |
| /// are detected in the flow graph |
| /// |
| template<class BlockT, class LoopT> |
| class LoopBase { |
| LoopT *ParentLoop; |
| // SubLoops - Loops contained entirely within this one. |
| std::vector<LoopT *> SubLoops; |
| |
| // Blocks - The list of blocks in this loop. First entry is the header node. |
| std::vector<BlockT*> Blocks; |
| |
| SmallPtrSet<const BlockT*, 8> DenseBlockSet; |
| |
| LoopBase(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION; |
| const LoopBase<BlockT, LoopT>& |
| operator=(const LoopBase<BlockT, LoopT> &) LLVM_DELETED_FUNCTION; |
| public: |
| /// Loop ctor - This creates an empty loop. |
| LoopBase() : ParentLoop(nullptr) {} |
| ~LoopBase() { |
| for (size_t i = 0, e = SubLoops.size(); i != e; ++i) |
| delete SubLoops[i]; |
| } |
| |
| /// getLoopDepth - Return the nesting level of this loop. An outer-most |
| /// loop has depth 1, for consistency with loop depth values used for basic |
| /// blocks, where depth 0 is used for blocks not inside any loops. |
| unsigned getLoopDepth() const { |
| unsigned D = 1; |
| for (const LoopT *CurLoop = ParentLoop; CurLoop; |
| CurLoop = CurLoop->ParentLoop) |
| ++D; |
| return D; |
| } |
| BlockT *getHeader() const { return Blocks.front(); } |
| LoopT *getParentLoop() const { return ParentLoop; } |
| |
| /// setParentLoop is a raw interface for bypassing addChildLoop. |
| void setParentLoop(LoopT *L) { ParentLoop = L; } |
| |
| /// contains - Return true if the specified loop is contained within in |
| /// this loop. |
| /// |
| bool contains(const LoopT *L) const { |
| if (L == this) return true; |
| if (!L) return false; |
| return contains(L->getParentLoop()); |
| } |
| |
| /// contains - Return true if the specified basic block is in this loop. |
| /// |
| bool contains(const BlockT *BB) const { |
| return DenseBlockSet.count(BB); |
| } |
| |
| /// contains - Return true if the specified instruction is in this loop. |
| /// |
| template<class InstT> |
| bool contains(const InstT *Inst) const { |
| return contains(Inst->getParent()); |
| } |
| |
| /// iterator/begin/end - Return the loops contained entirely within this loop. |
| /// |
| const std::vector<LoopT *> &getSubLoops() const { return SubLoops; } |
| std::vector<LoopT *> &getSubLoopsVector() { return SubLoops; } |
| typedef typename std::vector<LoopT *>::const_iterator iterator; |
| typedef typename std::vector<LoopT *>::const_reverse_iterator |
| reverse_iterator; |
| iterator begin() const { return SubLoops.begin(); } |
| iterator end() const { return SubLoops.end(); } |
| reverse_iterator rbegin() const { return SubLoops.rbegin(); } |
| reverse_iterator rend() const { return SubLoops.rend(); } |
| bool empty() const { return SubLoops.empty(); } |
| |
| /// getBlocks - Get a list of the basic blocks which make up this loop. |
| /// |
| const std::vector<BlockT*> &getBlocks() const { return Blocks; } |
| typedef typename std::vector<BlockT*>::const_iterator block_iterator; |
| block_iterator block_begin() const { return Blocks.begin(); } |
| block_iterator block_end() const { return Blocks.end(); } |
| |
| /// getNumBlocks - Get the number of blocks in this loop in constant time. |
| unsigned getNumBlocks() const { |
| return Blocks.size(); |
| } |
| |
| /// isLoopExiting - True if terminator in the block can branch to another |
| /// block that is outside of the current loop. |
| /// |
| bool isLoopExiting(const BlockT *BB) const { |
| typedef GraphTraits<const BlockT*> BlockTraits; |
| for (typename BlockTraits::ChildIteratorType SI = |
| BlockTraits::child_begin(BB), |
| SE = BlockTraits::child_end(BB); SI != SE; ++SI) { |
| if (!contains(*SI)) |
| return true; |
| } |
| return false; |
| } |
| |
| /// getNumBackEdges - Calculate the number of back edges to the loop header |
| /// |
| unsigned getNumBackEdges() const { |
| unsigned NumBackEdges = 0; |
| BlockT *H = getHeader(); |
| |
| typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; |
| for (typename InvBlockTraits::ChildIteratorType I = |
| InvBlockTraits::child_begin(H), |
| E = InvBlockTraits::child_end(H); I != E; ++I) |
| if (contains(*I)) |
| ++NumBackEdges; |
| |
| return NumBackEdges; |
| } |
| |
| //===--------------------------------------------------------------------===// |
| // 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. |
| |
| /// getExitingBlocks - Return all blocks inside the loop that have successors |
| /// outside of the loop. These are the blocks _inside of the current loop_ |
| /// which branch out. The returned list is always unique. |
| /// |
| void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const; |
| |
| /// getExitingBlock - If getExitingBlocks would return exactly one block, |
| /// return that block. Otherwise return null. |
| BlockT *getExitingBlock() const; |
| |
| /// 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(SmallVectorImpl<BlockT*> &ExitBlocks) const; |
| |
| /// getExitBlock - If getExitBlocks would return exactly one block, |
| /// return that block. Otherwise return null. |
| BlockT *getExitBlock() const; |
| |
| /// Edge type. |
| typedef std::pair<const BlockT*, const BlockT*> Edge; |
| |
| /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). |
| void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) 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. |
| /// |
| BlockT *getLoopPreheader() const; |
| |
| /// getLoopPredecessor - If the given loop's header has exactly one unique |
| /// predecessor outside the loop, return it. Otherwise return null. |
| /// This is less strict that the loop "preheader" concept, which requires |
| /// the predecessor to have exactly one successor. |
| /// |
| BlockT *getLoopPredecessor() const; |
| |
| /// getLoopLatch - If there is a single latch block for this loop, return it. |
| /// A latch block is a block that contains a branch back to the header. |
| BlockT *getLoopLatch() const; |
| |
| /// getLoopLatches - Return all loop latch blocks of this loop. A latch block |
| /// is a block that contains a branch back to the header. |
| void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const { |
| BlockT *H = getHeader(); |
| typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits; |
| for (typename InvBlockTraits::ChildIteratorType I = |
| InvBlockTraits::child_begin(H), |
| E = InvBlockTraits::child_end(H); I != E; ++I) |
| if (contains(*I)) |
| LoopLatches.push_back(*I); |
| } |
| |
| //===--------------------------------------------------------------------===// |
| // 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(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &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(LoopT *OldChild, LoopT *NewChild); |
| |
| /// addChildLoop - Add the specified loop to be a child of this loop. This |
| /// updates the loop depth of the new child. |
| /// |
| void addChildLoop(LoopT *NewChild) { |
| assert(!NewChild->ParentLoop && "NewChild already has a parent!"); |
| NewChild->ParentLoop = static_cast<LoopT *>(this); |
| SubLoops.push_back(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. |
| LoopT *removeChildLoop(iterator I) { |
| assert(I != SubLoops.end() && "Cannot remove end iterator!"); |
| LoopT *Child = *I; |
| assert(Child->ParentLoop == this && "Child is not a child of this loop!"); |
| SubLoops.erase(SubLoops.begin()+(I-begin())); |
| Child->ParentLoop = nullptr; |
| return Child; |
| } |
| |
| /// 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(BlockT *BB) { |
| Blocks.push_back(BB); |
| DenseBlockSet.insert(BB); |
| } |
| |
| /// reverseBlocks - interface to reverse Blocks[from, end of loop] in this loop |
| void reverseBlock(unsigned from) { |
| std::reverse(Blocks.begin() + from, Blocks.end()); |
| } |
| |
| /// reserveBlocks- interface to do reserve() for Blocks |
| void reserveBlocks(unsigned size) { |
| Blocks.reserve(size); |
| } |
| |
| /// 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(BlockT *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(BlockT *BB) { |
| RemoveFromVector(Blocks, BB); |
| DenseBlockSet.erase(BB); |
| } |
| |
| /// verifyLoop - Verify loop structure |
| void verifyLoop() const; |
| |
| /// verifyLoop - Verify loop structure of this loop and all nested loops. |
| void verifyLoopNest(DenseSet<const LoopT*> *Loops) const; |
| |
| void print(raw_ostream &OS, unsigned Depth = 0) const; |
| |
| protected: |
| friend class LoopInfoBase<BlockT, LoopT>; |
| explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) { |
| Blocks.push_back(BB); |
| DenseBlockSet.insert(BB); |
| } |
| }; |
| |
| template<class BlockT, class LoopT> |
| raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) { |
| Loop.print(OS); |
| return OS; |
| } |
| |
| // Implementation in LoopInfoImpl.h |
| #ifdef __GNUC__ |
| __extension__ extern template class LoopBase<BasicBlock, Loop>; |
| #endif |
| |
| class Loop : public LoopBase<BasicBlock, Loop> { |
| public: |
| Loop() {} |
| |
| /// isLoopInvariant - Return true if the specified value is loop invariant |
| /// |
| bool isLoopInvariant(Value *V) const; |
| |
| /// hasLoopInvariantOperands - Return true if all the operands of the |
| /// specified instruction are loop invariant. |
| bool hasLoopInvariantOperands(Instruction *I) const; |
| |
| /// makeLoopInvariant - If the given value is an instruction inside of the |
| /// loop and it can be hoisted, do so to make it trivially loop-invariant. |
| /// Return true if the value after any hoisting is loop invariant. This |
| /// function can be used as a slightly more aggressive replacement for |
| /// isLoopInvariant. |
| /// |
| /// If InsertPt is specified, it is the point to hoist instructions to. |
| /// If null, the terminator of the loop preheader is used. |
| /// |
| bool makeLoopInvariant(Value *V, bool &Changed, |
| Instruction *InsertPt = nullptr) const; |
| |
| /// makeLoopInvariant - If the given instruction is inside of the |
| /// loop and it can be hoisted, do so to make it trivially loop-invariant. |
| /// Return true if the instruction after any hoisting is loop invariant. This |
| /// function can be used as a slightly more aggressive replacement for |
| /// isLoopInvariant. |
| /// |
| /// If InsertPt is specified, it is the point to hoist instructions to. |
| /// If null, the terminator of the loop preheader is used. |
| /// |
| bool makeLoopInvariant(Instruction *I, bool &Changed, |
| Instruction *InsertPt = nullptr) 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. |
| /// |
| /// The IndVarSimplify pass transforms loops to have a canonical induction |
| /// variable. |
| /// |
| PHINode *getCanonicalInductionVariable() const; |
| |
| /// isLCSSAForm - Return true if the Loop is in LCSSA form |
| bool isLCSSAForm(DominatorTree &DT) const; |
| |
| /// isLoopSimplifyForm - Return true if the Loop is in the form that |
| /// the LoopSimplify form transforms loops to, which is sometimes called |
| /// normal form. |
| bool isLoopSimplifyForm() const; |
| |
| /// isSafeToClone - Return true if the loop body is safe to clone in practice. |
| bool isSafeToClone() const; |
| |
| /// Returns true if the loop is annotated parallel. |
| /// |
| /// A parallel loop can be assumed to not contain any dependencies between |
| /// iterations by the compiler. That is, any loop-carried dependency checking |
| /// can be skipped completely when parallelizing the loop on the target |
| /// machine. Thus, if the parallel loop information originates from the |
| /// programmer, e.g. via the OpenMP parallel for pragma, it is the |
| /// programmer's responsibility to ensure there are no loop-carried |
| /// dependencies. The final execution order of the instructions across |
| /// iterations is not guaranteed, thus, the end result might or might not |
| /// implement actual concurrent execution of instructions across multiple |
| /// iterations. |
| bool isAnnotatedParallel() const; |
| |
| /// Return the llvm.loop loop id metadata node for this loop if it is present. |
| /// |
| /// If this loop contains the same llvm.loop metadata on each branch to the |
| /// header then the node is returned. If any latch instruction does not |
| /// contain llvm.loop or or if multiple latches contain different nodes then |
| /// 0 is returned. |
| MDNode *getLoopID() const; |
| /// Set the llvm.loop loop id metadata for this loop. |
| /// |
| /// The LoopID metadata node will be added to each terminator instruction in |
| /// the loop that branches to the loop header. |
| /// |
| /// The LoopID metadata node should have one or more operands and the first |
| /// operand should should be the node itself. |
| void setLoopID(MDNode *LoopID) const; |
| |
| /// hasDedicatedExits - Return true if no exit block for the loop |
| /// has a predecessor that is outside the loop. |
| bool hasDedicatedExits() const; |
| |
| /// getUniqueExitBlocks - Return all unique successor blocks of this loop. |
| /// These are the blocks _outside of the current loop_ which are branched to. |
| /// This assumes that loop exits are in canonical form. |
| /// |
| void getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const; |
| |
| /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one |
| /// block, return that block. Otherwise return null. |
| BasicBlock *getUniqueExitBlock() const; |
| |
| void dump() const; |
| |
| /// \brief Return the debug location of the start of this loop. |
| /// This looks for a BB terminating instruction with a known debug |
| /// location by looking at the preheader and header blocks. If it |
| /// cannot find a terminating instruction with location information, |
| /// it returns an unknown location. |
| DebugLoc getStartLoc() const { |
| DebugLoc StartLoc; |
| BasicBlock *HeadBB; |
| |
| // Try the pre-header first. |
| if ((HeadBB = getLoopPreheader()) != nullptr) { |
| StartLoc = HeadBB->getTerminator()->getDebugLoc(); |
| if (!StartLoc.isUnknown()) |
| return StartLoc; |
| } |
| |
| // If we have no pre-header or there are no instructions with debug |
| // info in it, try the header. |
| HeadBB = getHeader(); |
| if (HeadBB) |
| StartLoc = HeadBB->getTerminator()->getDebugLoc(); |
| |
| return StartLoc; |
| } |
| |
| private: |
| friend class LoopInfoBase<BasicBlock, Loop>; |
| explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {} |
| }; |
| |
| //===----------------------------------------------------------------------===// |
| /// LoopInfo - This class builds and contains all of the top level loop |
| /// structures in the specified function. |
| /// |
| |
| template<class BlockT, class LoopT> |
| class LoopInfoBase { |
| // BBMap - Mapping of basic blocks to the inner most loop they occur in |
| DenseMap<BlockT *, LoopT *> BBMap; |
| std::vector<LoopT *> TopLevelLoops; |
| friend class LoopBase<BlockT, LoopT>; |
| friend class LoopInfo; |
| |
| void operator=(const LoopInfoBase &) LLVM_DELETED_FUNCTION; |
| LoopInfoBase(const LoopInfo &) LLVM_DELETED_FUNCTION; |
| public: |
| LoopInfoBase() { } |
| ~LoopInfoBase() { releaseMemory(); } |
| |
| void releaseMemory() { |
| for (typename std::vector<LoopT *>::iterator I = |
| TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I) |
| delete *I; // Delete all of the loops... |
| |
| BBMap.clear(); // Reset internal state of analysis |
| TopLevelLoops.clear(); |
| } |
| |
| /// iterator/begin/end - The interface to the top-level loops in the current |
| /// function. |
| /// |
| typedef typename std::vector<LoopT *>::const_iterator iterator; |
| typedef typename std::vector<LoopT *>::const_reverse_iterator |
| reverse_iterator; |
| iterator begin() const { return TopLevelLoops.begin(); } |
| iterator end() const { return TopLevelLoops.end(); } |
| reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); } |
| reverse_iterator rend() const { return TopLevelLoops.rend(); } |
| bool empty() const { return TopLevelLoops.empty(); } |
| |
| /// 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. |
| /// |
| LoopT *getLoopFor(const BlockT *BB) const { |
| return BBMap.lookup(const_cast<BlockT*>(BB)); |
| } |
| |
| /// operator[] - same as getLoopFor... |
| /// |
| const LoopT *operator[](const BlockT *BB) const { |
| return getLoopFor(BB); |
| } |
| |
| /// getLoopDepth - Return the loop nesting level of the specified block. A |
| /// depth of 0 means the block is not inside any loop. |
| /// |
| unsigned getLoopDepth(const BlockT *BB) const { |
| const LoopT *L = getLoopFor(BB); |
| return L ? L->getLoopDepth() : 0; |
| } |
| |
| // isLoopHeader - True if the block is a loop header node |
| bool isLoopHeader(BlockT *BB) const { |
| const LoopT *L = getLoopFor(BB); |
| return L && L->getHeader() == BB; |
| } |
| |
| /// 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. |
| LoopT *removeLoop(iterator I) { |
| assert(I != end() && "Cannot remove end iterator!"); |
| LoopT *L = *I; |
| assert(!L->getParentLoop() && "Not a top-level loop!"); |
| TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin())); |
| return L; |
| } |
| |
| /// 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(BlockT *BB, LoopT *L) { |
| if (!L) { |
| BBMap.erase(BB); |
| return; |
| } |
| BBMap[BB] = L; |
| } |
| |
| /// changeTopLevelLoop - Replace the specified loop in the top-level loops |
| /// list with the indicated loop. |
| void changeTopLevelLoop(LoopT *OldLoop, |
| LoopT *NewLoop) { |
| typename std::vector<LoopT *>::iterator I = |
| std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop); |
| assert(I != TopLevelLoops.end() && "Old loop not at top level!"); |
| *I = NewLoop; |
| assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop && |
| "Loops already embedded into a subloop!"); |
| } |
| |
| /// addTopLevelLoop - This adds the specified loop to the collection of |
| /// top-level loops. |
| void addTopLevelLoop(LoopT *New) { |
| assert(!New->getParentLoop() && "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(BlockT *BB) { |
| typename DenseMap<BlockT *, LoopT *>::iterator I = BBMap.find(BB); |
| if (I != BBMap.end()) { |
| for (LoopT *L = I->second; L; L = L->getParentLoop()) |
| L->removeBlockFromLoop(BB); |
| |
| BBMap.erase(I); |
| } |
| } |
| |
| // Internals |
| |
| static bool isNotAlreadyContainedIn(const LoopT *SubLoop, |
| const LoopT *ParentLoop) { |
| if (!SubLoop) return true; |
| if (SubLoop == ParentLoop) return false; |
| return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop); |
| } |
| |
| /// Create the loop forest using a stable algorithm. |
| void Analyze(DominatorTreeBase<BlockT> &DomTree); |
| |
| // Debugging |
| |
| void print(raw_ostream &OS) const; |
| }; |
| |
| // Implementation in LoopInfoImpl.h |
| #ifdef __GNUC__ |
| __extension__ extern template class LoopInfoBase<BasicBlock, Loop>; |
| #endif |
| |
| class LoopInfo : public FunctionPass { |
| LoopInfoBase<BasicBlock, Loop> LI; |
| friend class LoopBase<BasicBlock, Loop>; |
| |
| void operator=(const LoopInfo &) LLVM_DELETED_FUNCTION; |
| LoopInfo(const LoopInfo &) LLVM_DELETED_FUNCTION; |
| public: |
| static char ID; // Pass identification, replacement for typeid |
| |
| LoopInfo() : FunctionPass(ID) { |
| initializeLoopInfoPass(*PassRegistry::getPassRegistry()); |
| } |
| |
| LoopInfoBase<BasicBlock, Loop>& getBase() { return LI; } |
| |
| /// iterator/begin/end - The interface to the top-level loops in the current |
| /// function. |
| /// |
| typedef LoopInfoBase<BasicBlock, Loop>::iterator iterator; |
| typedef LoopInfoBase<BasicBlock, Loop>::reverse_iterator reverse_iterator; |
| inline iterator begin() const { return LI.begin(); } |
| inline iterator end() const { return LI.end(); } |
| inline reverse_iterator rbegin() const { return LI.rbegin(); } |
| inline reverse_iterator rend() const { return LI.rend(); } |
| bool empty() const { return LI.empty(); } |
| |
| /// 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. |
| /// |
| inline Loop *getLoopFor(const BasicBlock *BB) const { |
| return LI.getLoopFor(BB); |
| } |
| |
| /// operator[] - same as getLoopFor... |
| /// |
| inline const Loop *operator[](const BasicBlock *BB) const { |
| return LI.getLoopFor(BB); |
| } |
| |
| /// getLoopDepth - Return the loop nesting level of the specified block. A |
| /// depth of 0 means the block is not inside any loop. |
| /// |
| inline unsigned getLoopDepth(const BasicBlock *BB) const { |
| return LI.getLoopDepth(BB); |
| } |
| |
| // isLoopHeader - True if the block is a loop header node |
| inline bool isLoopHeader(BasicBlock *BB) const { |
| return LI.isLoopHeader(BB); |
| } |
| |
| /// runOnFunction - Calculate the natural loop information. |
| /// |
| bool runOnFunction(Function &F) override; |
| |
| void verifyAnalysis() const override; |
| |
| void releaseMemory() override { LI.releaseMemory(); } |
| |
| void print(raw_ostream &O, const Module* M = nullptr) const override; |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| /// 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. |
| inline Loop *removeLoop(iterator I) { return LI.removeLoop(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. |
| inline void changeLoopFor(BasicBlock *BB, Loop *L) { |
| LI.changeLoopFor(BB, L); |
| } |
| |
| /// changeTopLevelLoop - Replace the specified loop in the top-level loops |
| /// list with the indicated loop. |
| inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) { |
| LI.changeTopLevelLoop(OldLoop, NewLoop); |
| } |
| |
| /// addTopLevelLoop - This adds the specified loop to the collection of |
| /// top-level loops. |
| inline void addTopLevelLoop(Loop *New) { |
| LI.addTopLevelLoop(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) { |
| LI.removeBlock(BB); |
| } |
| |
| /// updateUnloop - Update LoopInfo after removing the last backedge from a |
| /// loop--now the "unloop". This updates the loop forest and parent loops for |
| /// each block so that Unloop is no longer referenced, but the caller must |
| /// actually delete the Unloop object. |
| void updateUnloop(Loop *Unloop); |
| |
| /// replacementPreservesLCSSAForm - Returns true if replacing From with To |
| /// everywhere is guaranteed to preserve LCSSA form. |
| bool replacementPreservesLCSSAForm(Instruction *From, Value *To) { |
| // Preserving LCSSA form is only problematic if the replacing value is an |
| // instruction. |
| Instruction *I = dyn_cast<Instruction>(To); |
| if (!I) return true; |
| // If both instructions are defined in the same basic block then replacement |
| // cannot break LCSSA form. |
| if (I->getParent() == From->getParent()) |
| return true; |
| // If the instruction is not defined in a loop then it can safely replace |
| // anything. |
| Loop *ToLoop = getLoopFor(I->getParent()); |
| if (!ToLoop) return true; |
| // If the replacing instruction is defined in the same loop as the original |
| // instruction, or in a loop that contains it as an inner loop, then using |
| // it as a replacement will not break LCSSA form. |
| return ToLoop->contains(getLoopFor(From->getParent())); |
| } |
| }; |
| |
| |
| // Allow clients to walk the list of nested loops... |
| template <> struct GraphTraits<const Loop*> { |
| typedef const Loop NodeType; |
| typedef LoopInfo::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 LoopInfo::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 |