X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FLoopInfo.h;h=de9a30d281a68fd0aa673384127d705287af1994;hb=bdc017edacb713119b24ab269d250a82d62fffeb;hp=acb5fd6c7a4a23b022574fbdc4e0549ef1dd5e05;hpb=7c6c55db4df35c9e0bbff89ceec52b0504862d7d;p=oota-llvm.git diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h index acb5fd6c7a4..de9a30d281a 100644 --- a/include/llvm/Analysis/LoopInfo.h +++ b/include/llvm/Analysis/LoopInfo.h @@ -2,8 +2,8 @@ // // 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 is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // @@ -31,74 +31,118 @@ #define LLVM_ANALYSIS_LOOP_INFO_H #include "llvm/Pass.h" +#include "llvm/ADT/DepthFirstIterator.h" #include "llvm/ADT/GraphTraits.h" #include "llvm/ADT/SmallVector.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/Streams.h" +#include +#include namespace llvm { +template +static void RemoveFromVector(std::vector &V, T *N) { + typename std::vector::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 PHINode; -class Instruction; +class Loop; +template class LoopInfoBase; +template class LoopBase; //===----------------------------------------------------------------------===// -/// Loop class - Instances of this class are used to represent loops that are -/// detected in the flow graph +/// LoopBase class - Instances of this class are used to represent loops that +/// are detected in the flow graph /// -class Loop { - Loop *ParentLoop; - std::vector SubLoops; // Loops contained entirely within this one - std::vector Blocks; // First entry is the header node - - Loop(const Loop &); // DO NOT IMPLEMENT - const Loop &operator=(const Loop &); // DO NOT IMPLEMENT +template +class LoopBase { + LoopT *ParentLoop; + // SubLoops - Loops contained entirely within this one. + std::vector SubLoops; + + // Blocks - The list of blocks in this loop. First entry is the header node. + std::vector Blocks; + + // DO NOT IMPLEMENT + LoopBase(const LoopBase &); + // DO NOT IMPLEMENT + const LoopBase&operator=(const LoopBase &); public: /// Loop ctor - This creates an empty loop. - Loop() : ParentLoop(0) {} - ~Loop() { - for (unsigned i = 0, e = SubLoops.size(); i != e; ++i) + LoopBase() : ParentLoop(0) {} + ~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 = 0; - for (const Loop *CurLoop = this; CurLoop; CurLoop = CurLoop->ParentLoop) + unsigned D = 1; + for (const LoopT *CurLoop = ParentLoop; CurLoop; + CurLoop = CurLoop->ParentLoop) ++D; return D; } - BasicBlock *getHeader() const { return Blocks.front(); } - Loop *getParentLoop() const { return ParentLoop; } + BlockT *getHeader() const { return Blocks.front(); } + LoopT *getParentLoop() const { return ParentLoop; } - /// contains - Return true of the specified basic block is in this loop + /// contains - Return true if the specified basic block is in this loop /// - bool contains(const BasicBlock *BB) const; + bool contains(const BlockT *BB) const { + return std::find(block_begin(), block_end(), BB) != block_end(); + } /// iterator/begin/end - Return the loops contained entirely within this loop. /// - const std::vector &getSubLoops() const { return SubLoops; } - typedef std::vector::const_iterator iterator; + const std::vector &getSubLoops() const { return SubLoops; } + typedef typename std::vector::const_iterator iterator; iterator begin() const { return SubLoops.begin(); } iterator end() const { return SubLoops.end(); } + bool empty() const { return SubLoops.empty(); } /// getBlocks - Get a list of the basic blocks which make up this loop. /// - const std::vector &getBlocks() const { return Blocks; } - typedef std::vector::const_iterator block_iterator; + const std::vector &getBlocks() const { return Blocks; } + typedef typename std::vector::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; + bool isLoopExit(const BlockT *BB) const { + typedef GraphTraits BlockTraits; + for (typename BlockTraits::ChildIteratorType SI = + BlockTraits::child_begin(const_cast(BB)), + SE = BlockTraits::child_end(const_cast(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; - - /// isLoopInvariant - Return true if the specified value is loop invariant - /// - bool isLoopInvariant(Value *V) const; + unsigned getNumBackEdges() const { + unsigned NumBackEdges = 0; + BlockT *H = getHeader(); + + typedef GraphTraits > InvBlockTraits; + for (typename InvBlockTraits::ChildIteratorType I = + InvBlockTraits::child_begin(const_cast(H)), + E = InvBlockTraits::child_end(const_cast(H)); I != E; ++I) + if (contains(*I)) + ++NumBackEdges; + + return NumBackEdges; + } //===--------------------------------------------------------------------===// // APIs for simple analysis of the loop. @@ -112,18 +156,130 @@ public: /// 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 &Blocks) const; + void getExitingBlocks(SmallVectorImpl &ExitingBlocks) const { + // Sort the blocks vector so that we can use binary search to do quick + // lookups. + SmallVector LoopBBs(block_begin(), block_end()); + std::sort(LoopBBs.begin(), LoopBBs.end()); + + typedef GraphTraits BlockTraits; + for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) + for (typename BlockTraits::ChildIteratorType I = + BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI); + I != E; ++I) + if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) { + // Not in current loop? It must be an exit block. + ExitingBlocks.push_back(*BI); + break; + } + } + + /// getExitingBlock - If getExitingBlocks would return exactly one block, + /// return that block. Otherwise return null. + BlockT *getExitingBlock() const { + SmallVector ExitingBlocks; + getExitingBlocks(ExitingBlocks); + if (ExitingBlocks.size() == 1) + return ExitingBlocks[0]; + return 0; + } /// 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 &Blocks) const; + void getExitBlocks(SmallVectorImpl &ExitBlocks) const { + // Sort the blocks vector so that we can use binary search to do quick + // lookups. + SmallVector LoopBBs(block_begin(), block_end()); + std::sort(LoopBBs.begin(), LoopBBs.end()); + + typedef GraphTraits BlockTraits; + for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) + for (typename BlockTraits::ChildIteratorType I = + BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI); + I != E; ++I) + if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) + // Not in current loop? It must be an exit block. + ExitBlocks.push_back(*I); + } + + /// getExitBlock - If getExitBlocks would return exactly one block, + /// return that block. Otherwise return null. + BlockT *getExitBlock() const { + SmallVector ExitBlocks; + getExitBlocks(ExitBlocks); + if (ExitBlocks.size() == 1) + return ExitBlocks[0]; + return 0; + } /// 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 is in canonical form. /// - void getUniqueExitBlocks(SmallVectorImpl &ExitBlocks) const; + void getUniqueExitBlocks(SmallVectorImpl &ExitBlocks) const { + // Sort the blocks vector so that we can use binary search to do quick + // lookups. + SmallVector LoopBBs(block_begin(), block_end()); + std::sort(LoopBBs.begin(), LoopBBs.end()); + + std::vector switchExitBlocks; + + for (block_iterator BI = block_begin(), BE = block_end(); BI != BE; ++BI) { + + BlockT *current = *BI; + switchExitBlocks.clear(); + + typedef GraphTraits BlockTraits; + typedef GraphTraits > InvBlockTraits; + for (typename BlockTraits::ChildIteratorType I = + BlockTraits::child_begin(*BI), E = BlockTraits::child_end(*BI); + I != E; ++I) { + if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I)) + // If block is inside the loop then it is not a exit block. + continue; + + typename InvBlockTraits::ChildIteratorType PI = + InvBlockTraits::child_begin(*I); + BlockT *firstPred = *PI; + + // If current basic block is this exit block's first predecessor + // then only insert exit block in to the output ExitBlocks vector. + // This ensures that same exit block is not inserted twice into + // ExitBlocks vector. + if (current != firstPred) + continue; + + // If a terminator has more then two successors, for example SwitchInst, + // then it is possible that there are multiple edges from current block + // to one exit block. + if (std::distance(BlockTraits::child_begin(current), + BlockTraits::child_end(current)) <= 2) { + ExitBlocks.push_back(*I); + continue; + } + + // In case of multiple edges from current block to exit block, collect + // only one edge in ExitBlocks. Use switchExitBlocks to keep track of + // duplicate edges. + if (std::find(switchExitBlocks.begin(), switchExitBlocks.end(), *I) + == switchExitBlocks.end()) { + switchExitBlocks.push_back(*I); + ExitBlocks.push_back(*I); + } + } + } + } + + /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one + /// block, return that block. Otherwise return null. + BlockT *getUniqueExitBlock() const { + SmallVector UniqueExitBlocks; + getUniqueExitBlocks(UniqueExitBlocks); + if (UniqueExitBlocks.size() == 1) + return UniqueExitBlocks[0]; + return 0; + } /// 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 @@ -132,36 +288,63 @@ public: /// /// This method returns null if there is no preheader for the loop. /// - BasicBlock *getLoopPreheader() const; + BlockT *getLoopPreheader() const { + // Keep track of nodes outside the loop branching to the header... + BlockT *Out = 0; + + // Loop over the predecessors of the header node... + BlockT *Header = getHeader(); + typedef GraphTraits BlockTraits; + typedef GraphTraits > InvBlockTraits; + for (typename InvBlockTraits::ChildIteratorType PI = + InvBlockTraits::child_begin(Header), + PE = InvBlockTraits::child_end(Header); PI != PE; ++PI) + if (!contains(*PI)) { // If the block is not in the loop... + if (Out && Out != *PI) + return 0; // Multiple predecessors outside the loop + Out = *PI; + } - /// 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; + // Make sure there is only one exit out of the preheader. + assert(Out && "Header of loop has no predecessors from outside loop?"); + typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out); + ++SI; + if (SI != BlockTraits::child_end(Out)) + return 0; // Multiple exits from the block, must not be a preheader. - /// 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; + // If there is exactly one preheader, return it. If there was zero, then + // Out is still null. + return Out; + } - /// 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; - - /// isLCSSAForm - Return true if the Loop is in LCSSA form - bool isLCSSAForm() 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. + /// A loop header in normal form has two edges into it: one from a preheader + /// and one from a latch block. + BlockT *getLoopLatch() const { + BlockT *Header = getHeader(); + typedef GraphTraits > InvBlockTraits; + typename InvBlockTraits::ChildIteratorType PI = + InvBlockTraits::child_begin(Header); + typename InvBlockTraits::ChildIteratorType PE = + InvBlockTraits::child_end(Header); + if (PI == PE) return 0; // no preds? + + BlockT *Latch = 0; + if (contains(*PI)) + Latch = *PI; + ++PI; + if (PI == PE) return 0; // only one pred? + + if (contains(*PI)) { + if (Latch) return 0; // multiple backedges + Latch = *PI; + } + ++PI; + if (PI != PE) return 0; // more than two preds + + return Latch; + } //===--------------------------------------------------------------------===// // APIs for updating loop information after changing the CFG @@ -173,35 +356,56 @@ public: /// 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); + void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase &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); + void replaceChildLoopWith(LoopT *OldChild, + LoopT *NewChild) { + assert(OldChild->ParentLoop == this && "This loop is already broken!"); + assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); + typename std::vector::iterator I = + std::find(SubLoops.begin(), SubLoops.end(), OldChild); + assert(I != SubLoops.end() && "OldChild not in loop!"); + *I = NewChild; + OldChild->ParentLoop = 0; + NewChild->ParentLoop = static_cast(this); + } /// 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); + void addChildLoop(LoopT *NewChild) { + assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); + NewChild->ParentLoop = static_cast(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. - Loop *removeChildLoop(iterator OldChild); + 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 = 0; + 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(BasicBlock *BB) { + void addBlockEntry(BlockT *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) { + void moveToHeader(BlockT *BB) { if (Blocks[0] == BB) return; for (unsigned i = 0; ; ++i) { assert(i != Blocks.size() && "Loop does not contain BB!"); @@ -216,84 +420,506 @@ public: /// 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 removeBlockFromLoop(BlockT *BB) { + RemoveFromVector(Blocks, BB); + } /// verifyLoop - Verify loop structure - void verifyLoop() const; + void verifyLoop() const { +#ifndef NDEBUG + assert (getHeader() && "Loop header is missing"); + assert (getLoopPreheader() && "Loop preheader is missing"); + assert (getLoopLatch() && "Loop latch is missing"); + for (iterator I = SubLoops.begin(), E = SubLoops.end(); I != E; ++I) + (*I)->verifyLoop(); +#endif + } - void print(std::ostream &O, unsigned Depth = 0) const; + void print(std::ostream &OS, unsigned Depth = 0) const { + OS << std::string(Depth*2, ' ') << "Loop at depth " << getLoopDepth() + << " containing: "; + + for (unsigned i = 0; i < getBlocks().size(); ++i) { + if (i) OS << ","; + BlockT *BB = getBlocks()[i]; + WriteAsOperand(OS, BB, false); + if (BB == getHeader()) OS << "
"; + if (BB == getLoopLatch()) OS << ""; + if (isLoopExit(BB)) OS << ""; + } + OS << "\n"; + + for (iterator I = begin(), E = end(); I != E; ++I) + (*I)->print(OS, Depth+2); + } + void print(std::ostream *O, unsigned Depth = 0) const { if (O) print(*O, Depth); } - void dump() const; -private: - friend class LoopInfo; - Loop(BasicBlock *BB) : ParentLoop(0) { + + void dump() const { + print(cerr); + } + +protected: + friend class LoopInfoBase; + explicit LoopBase(BlockT *BB) : ParentLoop(0) { Blocks.push_back(BB); } }; +class Loop : public LoopBase { +public: + Loop() {} + /// isLoopInvariant - Return true if the specified value is loop invariant + /// + bool isLoopInvariant(Value *V) const; + + /// isLoopInvariant - Return true if the specified instruction is + /// loop-invariant. + /// + bool isLoopInvariant(Instruction *I) const; + + /// makeLoopInvariant - If the given value is an instruciton 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 = 0) 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 = 0) 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; + + /// 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. + /// + /// The IndVarSimplify pass transforms loops to have a form that this + /// function easily understands. + /// + Value *getTripCount() const; + + /// getSmallConstantTripCount - Returns the trip count of this loop as a + /// normal unsigned value, if possible. Returns 0 if the trip count is unknown + /// of not constant. Will also return 0 if the trip count is very large + /// (>= 2^32) + unsigned getSmallConstantTripCount() const; + + /// getSmallConstantTripMultiple - Returns the largest constant divisor of the + /// trip count of this loop as a normal unsigned value, if possible. This + /// means that the actual trip count is always a multiple of the returned + /// value (don't forget the trip count could very well be zero as well!). + /// + /// Returns 1 if the trip count is unknown or not guaranteed to be the + /// multiple of a constant (which is also the case if the trip count is simply + /// constant, use getSmallConstantTripCount for that case), Will also return 1 + /// if the trip count is very large (>= 2^32). + unsigned getSmallConstantTripMultiple() const; + + /// isLCSSAForm - Return true if the Loop is in LCSSA form + bool isLCSSAForm() const; + +private: + friend class LoopInfoBase; + explicit Loop(BasicBlock *BB) : LoopBase(BB) {} +}; //===----------------------------------------------------------------------===// /// LoopInfo - This class builds and contains all of the top level loop /// structures in the specified function. /// -class LoopInfo : public FunctionPass { + +template +class LoopInfoBase { // BBMap - Mapping of basic blocks to the inner most loop they occur in - std::map BBMap; - std::vector TopLevelLoops; - friend class Loop; -public: - static char ID; // Pass identification, replacement for typeid + std::map BBMap; + std::vector TopLevelLoops; + friend class LoopBase; - LoopInfo() : FunctionPass(intptr_t(&ID)) {} - ~LoopInfo() { releaseMemory(); } + void operator=(const LoopInfoBase &); // do not implement + LoopInfoBase(const LoopInfo &); // do not implement +public: + LoopInfoBase() { } + ~LoopInfoBase() { releaseMemory(); } + + void releaseMemory() { + for (typename std::vector::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 std::vector::const_iterator iterator; + typedef typename std::vector::const_iterator iterator; iterator begin() const { return TopLevelLoops.begin(); } iterator end() const { return TopLevelLoops.end(); } - + 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. /// - Loop *getLoopFor(const BasicBlock *BB) const { - std::map::const_iterator I= - BBMap.find(const_cast(BB)); + LoopT *getLoopFor(const BlockT *BB) const { + typename std::map::const_iterator I= + BBMap.find(const_cast(BB)); return I != BBMap.end() ? I->second : 0; } - + /// operator[] - same as getLoopFor... /// - const Loop *operator[](const BasicBlock *BB) const { + const LoopT *operator[](const BlockT *BB) const { return getLoopFor(BB); } - - /// getLoopDepth - Return the loop nesting level of the specified block... + + /// 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 BasicBlock *BB) const { - const Loop *L = getLoopFor(BB); + 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(BasicBlock *BB) const { - const Loop *L = getLoopFor(BB); + 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() == 0 && "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) { + LoopT *&OldLoop = BBMap[BB]; + assert(OldLoop && "Block not in a loop yet!"); + OldLoop = 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::iterator I = + std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop); + assert(I != TopLevelLoops.end() && "Old loop not at top level!"); + *I = NewLoop; + assert(NewLoop->ParentLoop == 0 && OldLoop->ParentLoop == 0 && + "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() == 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(BlockT *BB) { + typename std::map::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 == 0) return true; + if (SubLoop == ParentLoop) return false; + return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop); + } + + void Calculate(DominatorTreeBase &DT) { + BlockT *RootNode = DT.getRootNode()->getBlock(); + + for (df_iterator NI = df_begin(RootNode), + NE = df_end(RootNode); NI != NE; ++NI) + if (LoopT *L = ConsiderForLoop(*NI, DT)) + TopLevelLoops.push_back(L); + } + + LoopT *ConsiderForLoop(BlockT *BB, DominatorTreeBase &DT) { + if (BBMap.find(BB) != BBMap.end()) return 0;// Haven't processed this node? + + std::vector TodoStack; + + // Scan the predecessors of BB, checking to see if BB dominates any of + // them. This identifies backedges which target this node... + typedef GraphTraits > InvBlockTraits; + for (typename InvBlockTraits::ChildIteratorType I = + InvBlockTraits::child_begin(BB), E = InvBlockTraits::child_end(BB); + I != E; ++I) + if (DT.dominates(BB, *I)) // If BB dominates it's predecessor... + TodoStack.push_back(*I); + + if (TodoStack.empty()) return 0; // No backedges to this block... + + // Create a new loop to represent this basic block... + LoopT *L = new LoopT(BB); + BBMap[BB] = L; + + BlockT *EntryBlock = BB->getParent()->begin(); + + while (!TodoStack.empty()) { // Process all the nodes in the loop + BlockT *X = TodoStack.back(); + TodoStack.pop_back(); + + if (!L->contains(X) && // As of yet unprocessed?? + DT.dominates(EntryBlock, X)) { // X is reachable from entry block? + // Check to see if this block already belongs to a loop. If this occurs + // then we have a case where a loop that is supposed to be a child of + // the current loop was processed before the current loop. When this + // occurs, this child loop gets added to a part of the current loop, + // making it a sibling to the current loop. We have to reparent this + // loop. + if (LoopT *SubLoop = + const_cast(getLoopFor(X))) + if (SubLoop->getHeader() == X && isNotAlreadyContainedIn(SubLoop, L)){ + // Remove the subloop from it's current parent... + assert(SubLoop->ParentLoop && SubLoop->ParentLoop != L); + LoopT *SLP = SubLoop->ParentLoop; // SubLoopParent + typename std::vector::iterator I = + std::find(SLP->SubLoops.begin(), SLP->SubLoops.end(), SubLoop); + assert(I != SLP->SubLoops.end() &&"SubLoop not a child of parent?"); + SLP->SubLoops.erase(I); // Remove from parent... + + // Add the subloop to THIS loop... + SubLoop->ParentLoop = L; + L->SubLoops.push_back(SubLoop); + } + + // Normal case, add the block to our loop... + L->Blocks.push_back(X); + + typedef GraphTraits > InvBlockTraits; + + // Add all of the predecessors of X to the end of the work stack... + TodoStack.insert(TodoStack.end(), InvBlockTraits::child_begin(X), + InvBlockTraits::child_end(X)); + } + } + + // If there are any loops nested within this loop, create them now! + for (typename std::vector::iterator I = L->Blocks.begin(), + E = L->Blocks.end(); I != E; ++I) + if (LoopT *NewLoop = ConsiderForLoop(*I, DT)) { + L->SubLoops.push_back(NewLoop); + NewLoop->ParentLoop = L; + } + + // Add the basic blocks that comprise this loop to the BBMap so that this + // loop can be found for them. + // + for (typename std::vector::iterator I = L->Blocks.begin(), + E = L->Blocks.end(); I != E; ++I) { + typename std::map::iterator BBMI = BBMap.find(*I); + if (BBMI == BBMap.end()) // Not in map yet... + BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level + } + + // Now that we have a list of all of the child loops of this loop, check to + // see if any of them should actually be nested inside of each other. We + // can accidentally pull loops our of their parents, so we must make sure to + // organize the loop nests correctly now. + { + std::map ContainingLoops; + for (unsigned i = 0; i != L->SubLoops.size(); ++i) { + LoopT *Child = L->SubLoops[i]; + assert(Child->getParentLoop() == L && "Not proper child loop?"); + + if (LoopT *ContainingLoop = ContainingLoops[Child->getHeader()]) { + // If there is already a loop which contains this loop, move this loop + // into the containing loop. + MoveSiblingLoopInto(Child, ContainingLoop); + --i; // The loop got removed from the SubLoops list. + } else { + // This is currently considered to be a top-level loop. Check to see + // if any of the contained blocks are loop headers for subloops we + // have already processed. + for (unsigned b = 0, e = Child->Blocks.size(); b != e; ++b) { + LoopT *&BlockLoop = ContainingLoops[Child->Blocks[b]]; + if (BlockLoop == 0) { // Child block not processed yet... + BlockLoop = Child; + } else if (BlockLoop != Child) { + LoopT *SubLoop = BlockLoop; + // Reparent all of the blocks which used to belong to BlockLoops + for (unsigned j = 0, e = SubLoop->Blocks.size(); j != e; ++j) + ContainingLoops[SubLoop->Blocks[j]] = Child; + + // There is already a loop which contains this block, that means + // that we should reparent the loop which the block is currently + // considered to belong to to be a child of this loop. + MoveSiblingLoopInto(SubLoop, Child); + --i; // We just shrunk the SubLoops list. + } + } + } + } + } + + return L; + } + + /// MoveSiblingLoopInto - This method moves the NewChild loop to live inside + /// of the NewParent Loop, instead of being a sibling of it. + void MoveSiblingLoopInto(LoopT *NewChild, + LoopT *NewParent) { + LoopT *OldParent = NewChild->getParentLoop(); + assert(OldParent && OldParent == NewParent->getParentLoop() && + NewChild != NewParent && "Not sibling loops!"); + + // Remove NewChild from being a child of OldParent + typename std::vector::iterator I = + std::find(OldParent->SubLoops.begin(), OldParent->SubLoops.end(), + NewChild); + assert(I != OldParent->SubLoops.end() && "Parent fields incorrect??"); + OldParent->SubLoops.erase(I); // Remove from parent's subloops list + NewChild->ParentLoop = 0; + + InsertLoopInto(NewChild, NewParent); + } + + /// InsertLoopInto - This inserts loop L into the specified parent loop. If + /// the parent loop contains a loop which should contain L, the loop gets + /// inserted into L instead. + void InsertLoopInto(LoopT *L, LoopT *Parent) { + BlockT *LHeader = L->getHeader(); + assert(Parent->contains(LHeader) && + "This loop should not be inserted here!"); + + // Check to see if it belongs in a child loop... + for (unsigned i = 0, e = static_cast(Parent->SubLoops.size()); + i != e; ++i) + if (Parent->SubLoops[i]->contains(LHeader)) { + InsertLoopInto(L, Parent->SubLoops[i]); + return; + } + + // If not, insert it here! + Parent->SubLoops.push_back(L); + L->ParentLoop = Parent; + } + + // Debugging + + void print(std::ostream &OS, const Module* ) const { + for (unsigned i = 0; i < TopLevelLoops.size(); ++i) + TopLevelLoops[i]->print(OS); + #if 0 + for (std::map::const_iterator I = BBMap.begin(), + E = BBMap.end(); I != E; ++I) + OS << "BB '" << I->first->getName() << "' level = " + << I->second->getLoopDepth() << "\n"; + #endif + } +}; + +class LoopInfo : public FunctionPass { + LoopInfoBase LI; + friend class LoopBase; + + void operator=(const LoopInfo &); // do not implement + LoopInfo(const LoopInfo &); // do not implement +public: + static char ID; // Pass identification, replacement for typeid + + LoopInfo() : FunctionPass(&ID) {} + + LoopInfoBase& getBase() { return LI; } + + /// iterator/begin/end - The interface to the top-level loops in the current + /// function. + /// + typedef LoopInfoBase::iterator iterator; + inline iterator begin() const { return LI.begin(); } + inline iterator end() const { return LI.end(); } + 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. /// virtual bool runOnFunction(Function &F); - virtual void releaseMemory(); + virtual void releaseMemory() { LI.releaseMemory(); } - void print(std::ostream &O, const Module* = 0) const; - void print(std::ostream *O, const Module* M = 0) const { - if (O) print(*O, M); + virtual void print(std::ostream &O, const Module* M = 0) const { + LI.print(O, M); } virtual void getAnalysisUsage(AnalysisUsage &AU) const; @@ -301,41 +927,47 @@ public: /// 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); + 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. - void changeLoopFor(BasicBlock *BB, Loop *L); + 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. - void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop); + inline void changeTopLevelLoop(Loop *OldLoop, Loop *NewLoop) { + LI.changeTopLevelLoop(OldLoop, 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); + 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); + void removeBlock(BasicBlock *BB) { + LI.removeBlock(BB); + } -private: - void Calculate(DominatorTree &DT); - Loop *ConsiderForLoop(BasicBlock *BB, DominatorTree &DT); - void MoveSiblingLoopInto(Loop *NewChild, Loop *NewParent); - void InsertLoopInto(Loop *L, Loop *Parent); + static bool isNotAlreadyContainedIn(const Loop *SubLoop, + const Loop *ParentLoop) { + return + LoopInfoBase::isNotAlreadyContainedIn(SubLoop, + ParentLoop); + } }; // Allow clients to walk the list of nested loops... template <> struct GraphTraits { typedef const Loop NodeType; - typedef std::vector::const_iterator ChildIteratorType; + typedef LoopInfo::iterator ChildIteratorType; static NodeType *getEntryNode(const Loop *L) { return L; } static inline ChildIteratorType child_begin(NodeType *N) { @@ -348,7 +980,7 @@ template <> struct GraphTraits { template <> struct GraphTraits { typedef Loop NodeType; - typedef std::vector::const_iterator ChildIteratorType; + typedef LoopInfo::iterator ChildIteratorType; static NodeType *getEntryNode(Loop *L) { return L; } static inline ChildIteratorType child_begin(NodeType *N) { @@ -359,9 +991,27 @@ template <> struct GraphTraits { } }; -} // End llvm namespace +template +void +LoopBase::addBasicBlockToLoop(BlockT *NewBB, + LoopInfoBase &LIB) { + assert((Blocks.empty() || LIB[getHeader()] == this) && + "Incorrect LI specified for this loop!"); + assert(NewBB && "Cannot add a null basic block to the loop!"); + assert(LIB[NewBB] == 0 && "BasicBlock already in the loop!"); + + LoopT *L = static_cast(this); + + // Add the loop mapping to the LoopInfo object... + LIB.BBMap[NewBB] = L; -// Make sure that any clients of this file link in LoopInfo.cpp -FORCE_DEFINING_FILE_TO_BE_LINKED(LoopInfo) + // Add the basic block to this loop and all parent loops... + while (L) { + L->Blocks.push_back(NewBB); + L = L->getParentLoop(); + } +} + +} // End llvm namespace #endif