X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;ds=inline;f=include%2Fllvm%2FAnalysis%2FLoopInfo.h;h=830754ded1f61a3bf06d2fddd3a855c3ead5fe56;hb=b09c146b116359616f6cbd4c8b3328607e00ff42;hp=a928ccdb8ef2b40faeb9294b6d35fdb23bf6a15d;hpb=75144f93eb7e4dbf22d308d21581ae255dd520c6;p=oota-llvm.git diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h index a928ccdb8ef..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... // //===----------------------------------------------------------------------===// @@ -30,19 +30,23 @@ #ifndef LLVM_ANALYSIS_LOOP_INFO_H #define LLVM_ANALYSIS_LOOP_INFO_H -#include "llvm/Pass.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/DenseSet.h" #include "llvm/ADT/DepthFirstIterator.h" #include "llvm/ADT/GraphTraits.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/raw_ostream.h" #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); @@ -51,6 +55,7 @@ static void RemoveFromVector(std::vector &V, T *N) { class DominatorTree; class LoopInfo; class Loop; +class PHINode; template class LoopInfoBase; template class LoopBase; @@ -67,10 +72,9 @@ class LoopBase { // 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 &); + 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) {} @@ -92,31 +96,61 @@ public: BlockT *getHeader() const { return Blocks.front(); } LoopT *getParentLoop() const { return ParentLoop; } - /// contains - Return true if the specified basic block is in this loop + /// 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. /// bool contains(const BlockT *BB) const { 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; } + 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 terminator in the 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)), @@ -155,80 +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()); - - 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; - } - } + void getExitingBlocks(SmallVectorImpl &ExitingBlocks) const; /// 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; - } + 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()); - - 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); - } + void getExitBlocks(SmallVectorImpl &ExitBlocks) const; /// 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; - } + BlockT *getExitBlock() const; - /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). - typedef std::pair Edge; - void getExitEdges(SmallVectorImpl &ExitEdges) 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()); + /// Edge type. + typedef std::pair Edge; - 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. - ExitEdges.push_back(std::make_pair(*BI, *I)); - } + /// 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 @@ -237,63 +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; + BlockT *getLoopPreheader() const; - // 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; - } + /// 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. - /// 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; - } + BlockT *getLoopLatch() const; //===--------------------------------------------------------------------===// // APIs for updating loop information after changing the CFG @@ -311,17 +246,7 @@ public: /// 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) { - 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); - } + 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. @@ -374,109 +299,13 @@ public: } /// verifyLoop - Verify loop structure - void verifyLoop() const { -#ifndef NDEBUG - assert(!Blocks.empty() && "Loop header is missing"); - assert(getHeader() && "Loop header is missing"); - - // 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()); - - // Check the individual blocks. - for (block_iterator I = block_begin(), E = block_end(); I != E; ++I) { - BlockT *BB = *I; - bool HasInsideLoopSuccs = false; - bool HasInsideLoopPreds = false; - SmallVector OutsideLoopPreds; - - typedef GraphTraits BlockTraits; - for (typename BlockTraits::ChildIteratorType SI = - BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB); - SI != SE; ++SI) - if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *SI)) { - HasInsideLoopSuccs = true; - break; - } - typedef GraphTraits > InvBlockTraits; - for (typename InvBlockTraits::ChildIteratorType PI = - InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB); - PI != PE; ++PI) { - if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), *PI)) - HasInsideLoopPreds = true; - else - OutsideLoopPreds.push_back(*PI); - } - - if (BB == getHeader()) { - assert(!OutsideLoopPreds.empty() && "Loop is unreachable!"); - } else if (!OutsideLoopPreds.empty()) { - // A non-header loop shouldn't be reachable from outside the loop, - // though it is permitted if the predecessor is not itself actually - // reachable. - BlockT *EntryBB = BB->getParent()->begin(); - for (df_iterator NI = df_begin(EntryBB), - NE = df_end(EntryBB); NI != NE; ++NI) - for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i) - assert(*NI != OutsideLoopPreds[i] && - "Loop has multiple entry points!"); - } - assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!"); - assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!"); - assert(BB != getHeader()->getParent()->begin() && - "Loop contains function entry block!"); - } - - // Check the subloops. - for (iterator I = begin(), E = end(); I != E; ++I) - // Each block in each subloop should be contained within this loop. - for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end(); - BI != BE; ++BI) { - assert(std::binary_search(LoopBBs.begin(), LoopBBs.end(), *BI) && - "Loop does not contain all the blocks of a subloop!"); - } - - // Check the parent loop pointer. - if (ParentLoop) { - assert(std::find(ParentLoop->begin(), ParentLoop->end(), this) != - ParentLoop->end() && - "Loop is not a subloop of its parent!"); - } -#endif - } + void verifyLoop() const; /// verifyLoop - Verify loop structure of this loop and all nested loops. - void verifyLoopNest() const { - // Verify this loop. - verifyLoop(); - // Verify the subloops. - for (iterator I = begin(), E = end(); I != E; ++I) - (*I)->verifyLoopNest(); - } + void verifyLoopNest(DenseSet *Loops) const; - void print(raw_ostream &OS, unsigned Depth = 0) const { - OS.indent(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"; + void print(raw_ostream &OS, unsigned Depth = 0) const; - for (iterator I = begin(), E = end(); I != E; ++I) - (*I)->print(OS, Depth+2); - } - - void dump() const { - print(errs()); - } - protected: friend class LoopInfoBase; explicit LoopBase(BlockT *BB) : ParentLoop(0) { @@ -484,6 +313,17 @@ protected: } }; +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() {} @@ -492,10 +332,9 @@ public: /// bool isLoopInvariant(Value *V) const; - /// isLoopInvariant - Return true if the specified instruction is - /// loop-invariant. - /// - bool isLoopInvariant(Instruction *I) 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. @@ -531,50 +370,24 @@ public: /// 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; + 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; - /// getUniqueExitBlocks - Return all unique successor blocks of this loop. + /// 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 is in canonical form. + /// This assumes that loop exits are in canonical form. /// void getUniqueExitBlocks(SmallVectorImpl &ExitBlocks) const; @@ -582,6 +395,8 @@ public: /// block, return that block. Otherwise return null. BasicBlock *getUniqueExitBlock() const; + void dump() const; + private: friend class LoopInfoBase; explicit Loop(BasicBlock *BB) : LoopBase(BB) {} @@ -595,16 +410,17 @@ private: template class LoopInfoBase { // BBMap - Mapping of basic blocks to the inner most loop they occur in - std::map BBMap; + DenseMap BBMap; std::vector TopLevelLoops; friend class LoopBase; + friend class LoopInfo; - void operator=(const LoopInfoBase &); // do not implement - LoopInfoBase(const LoopInfo &); // do not implement + 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 = TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I) @@ -613,30 +429,32 @@ public: 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_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 { - typename std::map::const_iterator I= - BBMap.find(const_cast(BB)); - return I != BBMap.end() ? I->second : 0; + return BBMap.lookup(const_cast(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. /// @@ -650,7 +468,7 @@ public: 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. @@ -661,16 +479,18 @@ public: 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; + 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, @@ -682,19 +502,19 @@ public: 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); + typename DenseMap::iterator I = BBMap.find(BB); if (I != BBMap.end()) { for (LoopT *L = I->second; L; L = L->getParentLoop()) L->removeBlockFromLoop(BB); @@ -702,208 +522,41 @@ public: 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; + /// Create the loop forest using a stable algorithm. + void Analyze(DominatorTreeBase &DomTree); - // 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 its 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 its 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) - BBMap.insert(std::make_pair(*I, L)); - - // 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(raw_ostream &OS) 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; - void operator=(const LoopInfo &); // do not implement - LoopInfo(const LoopInfo &); // do not implement + 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) {} + LoopInfo() : FunctionPass(ID) { + initializeLoopInfoPass(*PassRegistry::getPassRegistry()); + } LoopInfoBase& getBase() { return LI; } @@ -911,8 +564,11 @@ public: /// function. /// 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 @@ -949,7 +605,7 @@ public: 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 @@ -983,11 +639,31 @@ public: LI.removeBlock(BB); } - static bool isNotAlreadyContainedIn(const Loop *SubLoop, - const Loop *ParentLoop) { - return - LoopInfoBase::isNotAlreadyContainedIn(SubLoop, - ParentLoop); + /// 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())); } }; @@ -1019,27 +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!"); - - LoopT *L = static_cast(this); - - // Add the loop mapping to the LoopInfo object... - LIB.BBMap[NewBB] = L; - - // 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