X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FLoopInfo.h;h=830754ded1f61a3bf06d2fddd3a855c3ead5fe56;hb=b09c146b116359616f6cbd4c8b3328607e00ff42;hp=ab7cb7e03e55f577c6b236d6e9575b30ad7160ab;hpb=e856685710706e580a3ece2c59ced2cdf0719f55;p=oota-llvm.git diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h index ab7cb7e03e5..830754ded1f 100644 --- a/include/llvm/Analysis/LoopInfo.h +++ b/include/llvm/Analysis/LoopInfo.h @@ -8,7 +8,8 @@ //===----------------------------------------------------------------------===// // // 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 +// 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 @@ -22,7 +23,6 @@ // * whether or not a particular block branches out of the loop // * the successor blocks of the loop // * the loop depth -// * the trip count // * etc... // //===----------------------------------------------------------------------===// @@ -30,57 +30,56 @@ #ifndef LLVM_ANALYSIS_LOOP_INFO_H #define LLVM_ANALYSIS_LOOP_INFO_H -#include "llvm/Pass.h" -#include "llvm/Constants.h" -#include "llvm/Instructions.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/DenseSet.h" #include "llvm/ADT/DepthFirstIterator.h" #include "llvm/ADT/GraphTraits.h" -#include "llvm/ADT/SmallPtrSet.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallVector.h" #include "llvm/Analysis/Dominators.h" +#include "llvm/Pass.h" #include "llvm/Support/CFG.h" -#include "llvm/Support/Streams.h" +#include "llvm/Support/raw_ostream.h" #include -#include +#include + +namespace llvm { template -static void RemoveFromVector(std::vector &V, T *N) { +inline 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); } -namespace llvm { - class DominatorTree; class LoopInfo; +class Loop; class PHINode; -class Instruction; -template class LoopInfoBase; -template class LoopBase; - -typedef LoopBase Loop; +template class LoopInfoBase; +template class LoopBase; //===----------------------------------------------------------------------===// /// LoopBase class - Instances of this class are used to represent loops that /// are detected in the flow graph /// -template +template class LoopBase { - LoopBase *ParentLoop; + LoopT *ParentLoop; // SubLoops - Loops contained entirely within this one. - std::vector*> SubLoops; + std::vector SubLoops; // Blocks - The list of blocks in this loop. First entry is the header node. std::vector Blocks; - LoopBase(const LoopBase &); // DO NOT IMPLEMENT - const LoopBase&operator=(const LoopBase &);// DO NOT IMPLEMENT + LoopBase(const LoopBase &) LLVM_DELETED_FUNCTION; + const LoopBase& + operator=(const LoopBase &) LLVM_DELETED_FUNCTION; public: /// Loop ctor - This creates an empty loop. LoopBase() : ParentLoop(0) {} ~LoopBase() { - for (unsigned i = 0, e = SubLoops.size(); i != e; ++i) + for (size_t i = 0, e = SubLoops.size(); i != e; ++i) delete SubLoops[i]; } @@ -89,39 +88,69 @@ public: /// blocks, where depth 0 is used for blocks not inside any loops. unsigned getLoopDepth() const { unsigned D = 1; - for (const LoopBase *CurLoop = ParentLoop; CurLoop; + for (const LoopT *CurLoop = ParentLoop; CurLoop; CurLoop = CurLoop->ParentLoop) ++D; return D; } BlockT *getHeader() const { return Blocks.front(); } - LoopBase *getParentLoop() const { return ParentLoop; } + 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 == 0) return false; + return contains(L->getParentLoop()); + } - /// contains - Return true if the specified basic block is in this loop + /// contains - Return true if the specified basic block is in this loop. /// bool contains(const BlockT *BB) const { - return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end(); + return std::find(block_begin(), block_end(), BB) != block_end(); + } + + /// contains - Return true if the specified instruction is in this loop. + /// + template + bool contains(const InstT *Inst) const { + return contains(Inst->getParent()); } /// iterator/begin/end - Return the loops contained entirely within this loop. /// - const std::vector*> &getSubLoops() const { return SubLoops; } - typedef typename std::vector*>::const_iterator iterator; + const std::vector &getSubLoops() const { return SubLoops; } + std::vector &getSubLoopsVector() { return SubLoops; } + typedef typename std::vector::const_iterator iterator; + typedef typename std::vector::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 &getBlocks() const { return Blocks; } + std::vector &getBlocksVector() { 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 this block can branch to another block that is - /// outside of the current loop. + /// 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 isLoopExit(const BlockT *BB) const { + bool isLoopExiting(const BlockT *BB) const { typedef GraphTraits BlockTraits; for (typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(const_cast(BB)), @@ -148,14 +177,6 @@ public: return NumBackEdges; } - /// isLoopInvariant - Return true if the specified value is loop invariant - /// - inline bool isLoopInvariant(Value *V) const { - if (Instruction *I = dyn_cast(V)) - return !contains(I->getParent()); - return true; // All non-instructions are loop invariant - } - //===--------------------------------------------------------------------===// // APIs for simple analysis of the loop. // @@ -168,103 +189,26 @@ 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 &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()); + void getExitingBlocks(SmallVectorImpl &ExitingBlocks) const; - typedef GraphTraits BlockTraits; - for (typename std::vector::const_iterator BI = Blocks.begin(), - BE = Blocks.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; /// 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 &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()); + void getExitBlocks(SmallVectorImpl &ExitBlocks) const; - typedef GraphTraits BlockTraits; - for (typename std::vector::const_iterator BI = Blocks.begin(), - BE = Blocks.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; - /// 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 { - // 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 (typename std::vector::const_iterator BI = Blocks.begin(), - BE = Blocks.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); - } - } - } - } + /// Edge type. + typedef std::pair Edge; + + /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). + void getExitEdges(SmallVectorImpl &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 @@ -273,177 +217,18 @@ public: /// /// This method returns null if there is no preheader for the loop. /// - 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; - } - - // 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. - - // If there is exactly one preheader, return it. If there was zero, then - // Out is still null. - return Out; - } - - /// 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. - 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 + BlockT *getLoopPreheader() const; - return Latch; - } - - /// 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. - /// - inline PHINode *getCanonicalInductionVariable() const { - BlockT *H = getHeader(); - - BlockT *Incoming = 0, *Backedge = 0; - typedef GraphTraits > InvBlockTraits; - typename InvBlockTraits::ChildIteratorType PI = - InvBlockTraits::child_begin(H); - assert(PI != InvBlockTraits::child_end(H) && - "Loop must have at least one backedge!"); - Backedge = *PI++; - if (PI == InvBlockTraits::child_end(H)) return 0; // dead loop - Incoming = *PI++; - if (PI != InvBlockTraits::child_end(H)) return 0; // multiple backedges? - - if (contains(Incoming)) { - if (contains(Backedge)) - return 0; - std::swap(Incoming, Backedge); - } else if (!contains(Backedge)) - return 0; - - // Loop over all of the PHI nodes, looking for a canonical indvar. - for (typename BlockT::iterator I = H->begin(); isa(I); ++I) { - PHINode *PN = cast(I); - if (ConstantInt *CI = - dyn_cast(PN->getIncomingValueForBlock(Incoming))) - if (CI->isNullValue()) - if (Instruction *Inc = - dyn_cast(PN->getIncomingValueForBlock(Backedge))) - if (Inc->getOpcode() == Instruction::Add && - Inc->getOperand(0) == PN) - if (ConstantInt *CI = dyn_cast(Inc->getOperand(1))) - if (CI->equalsInt(1)) - return PN; - } - return 0; - } - - /// 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. - /// - inline Instruction *getCanonicalInductionVariableIncrement() const { - if (PHINode *PN = getCanonicalInductionVariable()) { - bool P1InLoop = contains(PN->getIncomingBlock(1)); - return cast(PN->getIncomingValue(P1InLoop)); - } - return 0; - } - - /// 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. + /// 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. /// - inline Value *getTripCount() const { - // Canonical loops will end with a 'cmp ne I, V', where I is the incremented - // canonical induction variable and V is the trip count of the loop. - Instruction *Inc = getCanonicalInductionVariableIncrement(); - if (Inc == 0) return 0; - PHINode *IV = cast(Inc->getOperand(0)); - - BlockT *BackedgeBlock = - IV->getIncomingBlock(contains(IV->getIncomingBlock(1))); - - if (BranchInst *BI = dyn_cast(BackedgeBlock->getTerminator())) - if (BI->isConditional()) { - if (ICmpInst *ICI = dyn_cast(BI->getCondition())) { - if (ICI->getOperand(0) == Inc) { - if (BI->getSuccessor(0) == getHeader()) { - if (ICI->getPredicate() == ICmpInst::ICMP_NE) - return ICI->getOperand(1); - } else if (ICI->getPredicate() == ICmpInst::ICMP_EQ) { - return ICI->getOperand(1); - } - } - } - } + BlockT *getLoopPredecessor() const; - return 0; - } - - /// isLCSSAForm - Return true if the Loop is in LCSSA form - inline bool isLCSSAForm() const { - // Sort the blocks vector so that we can use binary search to do quick - // lookups. - SmallPtrSet LoopBBs(block_begin(), block_end()); - - for (block_iterator BI = block_begin(), E = block_end(); BI != E; ++BI) { - BlockT *BB = *BI; - for (typename BlockT::iterator I = BB->begin(), E = BB->end(); I != E;++I) - for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; - ++UI) { - BlockT *UserBB = cast(*UI)->getParent(); - if (PHINode *P = dyn_cast(*UI)) { - unsigned OperandNo = UI.getOperandNo(); - UserBB = P->getIncomingBlock(OperandNo/2); - } - - // Check the current block, as a fast-path. Most values are used in - // the same block they are defined in. - if (UserBB != BB && !LoopBBs.count(UserBB)) - return false; - } - } - - return true; - } + /// 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; //===--------------------------------------------------------------------===// // APIs for updating loop information after changing the CFG @@ -455,39 +240,29 @@ 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(BlockT *NewBB, LoopInfoBase &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(LoopBase *OldChild, - LoopBase *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 = this; - } + 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(LoopBase *NewChild) { + void addChildLoop(LoopT *NewChild) { assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); - NewChild->ParentLoop = this; + 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. - LoopBase *removeChildLoop(iterator I) { + LoopT *removeChildLoop(iterator I) { assert(I != SubLoops.end() && "Cannot remove end iterator!"); - LoopBase *Child = *I; + LoopT *Child = *I; assert(Child->ParentLoop == this && "Child is not a child of this loop!"); SubLoops.erase(SubLoops.begin()+(I-begin())); Child->ParentLoop = 0; @@ -524,445 +299,371 @@ public: } /// verifyLoop - Verify loop structure - void verifyLoop() const { -#ifndef NDEBUG - assert (getHeader() && "Loop header is missing"); - assert (getLoopPreheader() && "Loop preheader is missing"); - assert (getLoopLatch() && "Loop latch is missing"); - for (typename std::vector*>::const_iterator I = - SubLoops.begin(), E = SubLoops.end(); I != E; ++I) - (*I)->verifyLoop(); -#endif - } + void verifyLoop() const; - void print(std::ostream &OS, unsigned Depth = 0) const { - OS << std::string(Depth*2, ' ') << "Loop Containing: "; + /// verifyLoop - Verify loop structure of this loop and all nested loops. + void verifyLoopNest(DenseSet *Loops) const; - for (unsigned i = 0; i < getBlocks().size(); ++i) { - if (i) OS << ","; - WriteAsOperand(OS, getBlocks()[i], false); - } - OS << "\n"; + void print(raw_ostream &OS, unsigned Depth = 0) const; - 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 { - print(cerr); - } - -private: - friend class LoopInfoBase; - LoopBase(BlockT *BB) : ParentLoop(0) { +protected: + friend class LoopInfoBase; + explicit LoopBase(BlockT *BB) : ParentLoop(0) { Blocks.push_back(BB); } }; +template +raw_ostream& operator<<(raw_ostream &OS, const LoopBase &Loop) { + Loop.print(OS); + return OS; +} + +// Implementation in LoopInfoImpl.h +#ifdef __GNUC__ +__extension__ extern template class LoopBase; +#endif + +class Loop : public LoopBase { +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 = 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; + + /// 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; + + /// 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 &ExitBlocks) const; + + /// getUniqueExitBlock - If getUniqueExitBlocks would return exactly one + /// block, return that block. Otherwise return null. + BasicBlock *getUniqueExitBlock() const; + + void dump() 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. /// -template +template class LoopInfoBase { // BBMap - Mapping of basic blocks to the inner most loop they occur in - std::map*> BBMap; - std::vector*> TopLevelLoops; - friend class LoopBase; - + DenseMap BBMap; + std::vector TopLevelLoops; + friend class LoopBase; + 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* >::iterator I = + 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 typename std::vector*>::const_iterator iterator; + typedef typename std::vector::const_iterator iterator; + typedef typename std::vector::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. /// - LoopBase *getLoopFor(const BlockT *BB) const { - typename std::map*>::const_iterator I= - BBMap.find(const_cast(BB)); - return I != BBMap.end() ? I->second : 0; + LoopT *getLoopFor(const BlockT *BB) const { + return BBMap.lookup(const_cast(BB)); } - + /// operator[] - same as getLoopFor... /// - const LoopBase *operator[](const BlockT *BB) const { + 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 LoopBase *L = getLoopFor(BB); + 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 LoopBase *L = getLoopFor(BB); + 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. - LoopBase *removeLoop(iterator I) { + LoopT *removeLoop(iterator I) { assert(I != end() && "Cannot remove end iterator!"); - LoopBase *L = *I; + 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, LoopBase *L) { - LoopBase *&OldLoop = BBMap[BB]; - assert(OldLoop && "Block not in a loop yet!"); - OldLoop = L; + 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(LoopBase *OldLoop, - LoopBase *NewLoop) { - typename std::vector*>::iterator I = + 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(LoopBase *New) { + 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); + typename DenseMap::iterator I = BBMap.find(BB); if (I != BBMap.end()) { - for (LoopBase *L = I->second; L; L = L->getParentLoop()) + for (LoopT *L = I->second; L; L = L->getParentLoop()) L->removeBlockFromLoop(BB); BBMap.erase(I); } } - + // Internals - - static bool isNotAlreadyContainedIn(LoopBase *SubLoop, - LoopBase *ParentLoop) { + + 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 (LoopBase *L = ConsiderForLoop(*NI, DT)) - TopLevelLoops.push_back(L); - } - - LoopBase *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... - LoopBase *L = new LoopBase(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 (LoopBase *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); - LoopBase *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 (LoopBase *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.lower_bound(*I); - if (BBMI == BBMap.end() || BBMI->first != *I) // Not in map yet... - BBMap.insert(BBMI, std::make_pair(*I, L)); // Must be at this level - } + /// Create the loop forest using a stable algorithm. + void Analyze(DominatorTreeBase &DomTree); - // 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) { - LoopBase *Child = L->SubLoops[i]; - assert(Child->getParentLoop() == L && "Not proper child loop?"); - - if (LoopBase *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) { - LoopBase *&BlockLoop = ContainingLoops[Child->Blocks[b]]; - if (BlockLoop == 0) { // Child block not processed yet... - BlockLoop = Child; - } else if (BlockLoop != Child) { - LoopBase *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(LoopBase *NewChild, - LoopBase *NewParent) { - LoopBase *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(LoopBase *L, LoopBase *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 = 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 - } + + void print(raw_ostream &OS) const; }; +// Implementation in LoopInfoImpl.h +#ifdef __GNUC__ +__extension__ extern template class LoopInfoBase; +#endif + class LoopInfo : public FunctionPass { - LoopInfoBase* LI; - friend class LoopBase; - + LoopInfoBase LI; + friend class LoopBase; + + void operator=(const LoopInfo &) LLVM_DELETED_FUNCTION; + LoopInfo(const LoopInfo &) LLVM_DELETED_FUNCTION; public: static char ID; // Pass identification, replacement for typeid - LoopInfo() : FunctionPass(intptr_t(&ID)) { - LI = new LoopInfoBase(); + LoopInfo() : FunctionPass(ID) { + initializeLoopInfoPass(*PassRegistry::getPassRegistry()); } - - ~LoopInfo() { delete LI; } - LoopInfoBase& getBase() { return *LI; } + LoopInfoBase& getBase() { return LI; } /// iterator/begin/end - The interface to the top-level loops in the current /// function. /// - typedef std::vector::const_iterator iterator; - inline iterator begin() const { return LI->begin(); } - inline iterator end() const { return LI->end(); } + typedef LoopInfoBase::iterator iterator; + typedef LoopInfoBase::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); + return LI.getLoopFor(BB); } /// operator[] - same as getLoopFor... /// inline const Loop *operator[](const BasicBlock *BB) const { - return LI->getLoopFor(BB); + 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); + return LI.getLoopDepth(BB); } // isLoopHeader - True if the block is a loop header node inline bool isLoopHeader(BasicBlock *BB) const { - return LI->isLoopHeader(BB); + return LI.isLoopHeader(BB); } - /// isAnalysis - Return true if this pass is implementing an analysis pass. - bool isAnalysis() const { return true; } - /// runOnFunction - Calculate the natural loop information. /// virtual bool runOnFunction(Function &F); - virtual void releaseMemory() { LI->releaseMemory(); } + virtual void verifyAnalysis() const; - virtual void print(std::ostream &O, const Module* M = 0) const { - if (O) LI->print(O, M); - } + virtual void releaseMemory() { LI.releaseMemory(); } + + virtual void print(raw_ostream &O, const Module* M = 0) const; 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. - inline Loop *removeLoop(iterator I) { return LI->removeLoop(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. inline void changeLoopFor(BasicBlock *BB, Loop *L) { - LI->changeLoopFor(BB, 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); + 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); + 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); + 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(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())); } }; @@ -970,7 +671,7 @@ public: // 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) { @@ -983,7 +684,7 @@ 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) { @@ -994,28 +695,6 @@ template <> struct GraphTraits { } }; -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!"); - - // Add the loop mapping to the LoopInfo object... - LIB.BBMap[NewBB] = this; - - // Add the basic block to this loop and all parent loops... - LoopBase *L = this; - while (L) { - L->Blocks.push_back(NewBB); - L = L->getParentLoop(); - } -} - } // End llvm namespace -// Make sure that any clients of this file link in LoopInfo.cpp -FORCE_DEFINING_FILE_TO_BE_LINKED(LoopInfo) - #endif