diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h index 86dc571fd4c..32115aea3f0 100644 --- a/include/llvm/Analysis/LoopInfo.h +++ b/include/llvm/Analysis/LoopInfo.h @@ -31,8 +31,22 @@ #define LLVM_ANALYSIS_LOOP_INFO_H #include "llvm/Pass.h" +#include "llvm/Constants.h" +#include "llvm/Instructions.h" #include "llvm/ADT/GraphTraits.h" +#include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/Streams.h" +#include +#include + +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); +} namespace llvm { @@ -42,64 +56,88 @@ class PHINode; class Instruction; //===----------------------------------------------------------------------===// -/// Loop class - Instances of this class are used to represent loops that are +/// 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 +template +class LoopBase { + LoopBase *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 + LoopBase(const LoopBase &); // DO NOT IMPLEMENT + const LoopBase &operator=(const LoopBase &); // DO NOT IMPLEMENT public: /// Loop ctor - This creates an empty loop. - Loop() : ParentLoop(0) {} - ~Loop() { + LoopBase() : ParentLoop(0) {} + ~LoopBase() { for (unsigned i = 0, e = SubLoops.size(); i != e; ++i) delete SubLoops[i]; } unsigned getLoopDepth() const { unsigned D = 0; - for (const Loop *CurLoop = this; CurLoop; CurLoop = CurLoop->ParentLoop) + for (const LoopBase *CurLoop = this; CurLoop; + CurLoop = CurLoop->ParentLoop) ++D; return D; } - BasicBlock *getHeader() const { return Blocks.front(); } - Loop *getParentLoop() const { return ParentLoop; } + BlockT *getHeader() const { return Blocks.front(); } + LoopBase *getParentLoop() const { return ParentLoop; } /// contains - Return true of the specified basic block is in this loop /// - bool contains(const BasicBlock *BB) const; + bool contains(const BlockT *BB) const { + return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.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 { + for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB); + SI != SE; ++SI) { + if (!contains(*SI)) + return true; + } + return false; + } /// getNumBackEdges - Calculate the number of back edges to the loop header /// - unsigned getNumBackEdges() const; + unsigned getNumBackEdges() const { + unsigned NumBackEdges = 0; + BlockT *H = getHeader(); + + for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I) + if (contains(*I)) + ++NumBackEdges; + + return NumBackEdges; + } /// isLoopInvariant - Return true if the specified value is loop invariant /// - bool isLoopInvariant(Value *V) const; + 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. @@ -113,18 +151,91 @@ 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()); + + for (typename std::vector::const_iterator BI = Blocks.begin(), + BE = Blocks.end(); BI != BE; ++BI) + for (succ_iterator I = succ_begin(*BI), E = succ_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; + } + } /// 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()); + + for (typename std::vector::const_iterator BI = Blocks.begin(), + BE = Blocks.end(); BI != BE; ++BI) + for (succ_iterator I = succ_begin(*BI), E = succ_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); + } /// 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 (typename std::vector::const_iterator BI = Blocks.begin(), + BE = Blocks.end(); BI != BE; ++BI) { + + BlockT *current = *BI; + switchExitBlocks.clear(); + + for (succ_iterator I = succ_begin(*BI), E = succ_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; + + pred_iterator PI = pred_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 (current->getTerminator()->getNumSuccessors() <= 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); + } + } + } + } /// 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 @@ -133,36 +244,162 @@ 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(); + for (pred_iterator PI = pred_begin(Header), PE = pred_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?"); + succ_iterator SI = succ_begin(Out); + ++SI; + if (SI != succ_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. - BasicBlock *getLoopLatch() const; + BlockT *getLoopLatch() const { + BlockT *Header = getHeader(); + pred_iterator PI = pred_begin(Header), PE = pred_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; + } /// 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; + PHINode *getCanonicalInductionVariable() const { + BlockT *H = getHeader(); + + BlockT *Incoming = 0, *Backedge = 0; + pred_iterator PI = pred_begin(H); + assert(PI != pred_end(H) && "Loop must have at least one backedge!"); + Backedge = *PI++; + if (PI == pred_end(H)) return 0; // dead loop + Incoming = *PI++; + if (PI != pred_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 (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. /// - Instruction *getCanonicalInductionVariableIncrement() const; + 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. /// - Value *getTripCount() const; + 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); + } + } + } + + return 0; + } /// isLCSSAForm - Return true if the Loop is in LCSSA form - bool isLCSSAForm() const; + 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; + } //===--------------------------------------------------------------------===// // APIs for updating loop information after changing the CFG @@ -174,35 +411,56 @@ 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, LoopInfo &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(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; + } /// 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(LoopBase *NewChild) { + assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); + NewChild->ParentLoop = 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); + LoopBase *removeChildLoop(iterator I) { + assert(I != SubLoops.end() && "Cannot remove end iterator!"); + LoopBase *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!"); @@ -217,23 +475,51 @@ 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 (typename std::vector*>::const_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 Containing: "; + + for (unsigned i = 0; i < getBlocks().size(); ++i) { + if (i) OS << ","; + WriteAsOperand(OS, getBlocks()[i], false); + } + 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; + + void dump() const { + print(cerr); + } + private: friend class LoopInfo; - Loop(BasicBlock *BB) : ParentLoop(0) { + LoopBase(BlockT *BB) : ParentLoop(0) { Blocks.push_back(BB); } }; +typedef LoopBase Loop; //===----------------------------------------------------------------------===// @@ -244,7 +530,7 @@ class LoopInfo : public FunctionPass { // BBMap - Mapping of basic blocks to the inner most loop they occur in std::map BBMap; std::vector TopLevelLoops; - friend class Loop; + friend class LoopBase; public: static char ID; // Pass identification, replacement for typeid @@ -360,6 +646,24 @@ template <> struct GraphTraits { } }; +template +void LoopBase::addBasicBlockToLoop(BlockT *NewBB, LoopInfo &LI) { + assert((Blocks.empty() || LI[getHeader()] == this) && + "Incorrect LI specified for this loop!"); + assert(NewBB && "Cannot add a null basic block to the loop!"); + assert(LI[NewBB] == 0 && "BasicBlock already in the loop!"); + + // Add the loop mapping to the LoopInfo object... + LI.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 diff --git a/include/llvm/Analysis/LoopPass.h b/include/llvm/Analysis/LoopPass.h index 6d6d94c71d3..b945b9907f9 100644 --- a/include/llvm/Analysis/LoopPass.h +++ b/include/llvm/Analysis/LoopPass.h @@ -23,7 +23,6 @@ namespace llvm { class LPPassManager; -class Loop; class Function; class LoopPass : public Pass { diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h index 9e9da6c32c6..a52f273b2c7 100644 --- a/include/llvm/Analysis/ScalarEvolution.h +++ b/include/llvm/Analysis/ScalarEvolution.h @@ -22,6 +22,7 @@ #define LLVM_ANALYSIS_SCALAREVOLUTION_H #include "llvm/Pass.h" +#include "llvm/Analysis/LoopInfo.h" #include "llvm/Support/DataTypes.h" #include "llvm/Support/Streams.h" #include @@ -32,8 +33,6 @@ namespace llvm { class Instruction; class Type; class ConstantRange; - class Loop; - class LoopInfo; class SCEVHandle; class ScalarEvolution; diff --git a/include/llvm/Transforms/Utils/Cloning.h b/include/llvm/Transforms/Utils/Cloning.h index 53e47a3c195..1d9d651b6ca 100644 --- a/include/llvm/Transforms/Utils/Cloning.h +++ b/include/llvm/Transforms/Utils/Cloning.h @@ -20,13 +20,12 @@ #include #include "llvm/ADT/DenseMap.h" +#include "llvm/Analysis/LoopInfo.h" namespace llvm { class Module; class Function; -class Loop; -class LoopInfo; class Pass; class LPPassManager; class BasicBlock; diff --git a/include/llvm/Transforms/Utils/FunctionUtils.h b/include/llvm/Transforms/Utils/FunctionUtils.h index cf8abdf800a..078fab00400 100644 --- a/include/llvm/Transforms/Utils/FunctionUtils.h +++ b/include/llvm/Transforms/Utils/FunctionUtils.h @@ -14,13 +14,13 @@ #ifndef LLVM_TRANSFORMS_UTILS_FUNCTION_H #define LLVM_TRANSFORMS_UTILS_FUNCTION_H -#include +#include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/LoopInfo.h" #include namespace llvm { class BasicBlock; class Function; - class Loop; /// ExtractCodeRegion - rip out a sequence of basic blocks into a new function /// diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp index 09dca27958b..20ca8929971 100644 --- a/lib/Analysis/LoopInfo.cpp +++ b/lib/Analysis/LoopInfo.cpp @@ -34,69 +34,9 @@ X("loops", "Natural Loop Construction", true); //===----------------------------------------------------------------------===// // Loop implementation // -bool Loop::contains(const BasicBlock *BB) const { - return std::find(Blocks.begin(), Blocks.end(), BB) != Blocks.end(); -} - -bool Loop::isLoopExit(const BasicBlock *BB) const { - for (succ_const_iterator SI = succ_begin(BB), SE = succ_end(BB); - SI != SE; ++SI) { - if (!contains(*SI)) - return true; - } - return false; -} /// getNumBackEdges - Calculate the number of back edges to the loop header. /// -unsigned Loop::getNumBackEdges() const { - unsigned NumBackEdges = 0; - BasicBlock *H = getHeader(); - - for (pred_iterator I = pred_begin(H), E = pred_end(H); I != E; ++I) - if (contains(*I)) - ++NumBackEdges; - - return NumBackEdges; -} - -/// isLoopInvariant - Return true if the specified value is loop invariant -/// -bool Loop::isLoopInvariant(Value *V) const { - if (Instruction *I = dyn_cast(V)) - return !contains(I->getParent()); - return true; // All non-instructions are loop invariant -} - -void Loop::print(std::ostream &OS, unsigned Depth) const { - OS << std::string(Depth*2, ' ') << "Loop Containing: "; - - for (unsigned i = 0; i < getBlocks().size(); ++i) { - if (i) OS << ","; - WriteAsOperand(OS, getBlocks()[i], false); - } - OS << "\n"; - - for (iterator I = begin(), E = end(); I != E; ++I) - (*I)->print(OS, Depth+2); -} - -/// verifyLoop - Verify loop structure -void Loop::verifyLoop() const { -#ifndef NDEBUG - assert (getHeader() && "Loop header is missing"); - assert (getLoopPreheader() && "Loop preheader is missing"); - assert (getLoopLatch() && "Loop latch is missing"); - for (std::vector::const_iterator I = SubLoops.begin(), E = SubLoops.end(); - I != E; ++I) - (*I)->verifyLoop(); -#endif -} - -void Loop::dump() const { - print(cerr); -} - //===----------------------------------------------------------------------===// // LoopInfo implementation @@ -341,341 +281,5 @@ void LoopInfo::removeBlock(BasicBlock *BB) { } } - -//===----------------------------------------------------------------------===// -// APIs for simple analysis of the loop. -// - -/// getExitingBlocks - Return all blocks inside the loop that have successors -/// outside of the loop. These are the blocks _inside of the current loop_ -/// which branch out. The returned list is always unique. -/// -void Loop::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()); - - for (std::vector::const_iterator BI = Blocks.begin(), - BE = Blocks.end(); BI != BE; ++BI) - for (succ_iterator I = succ_begin(*BI), E = succ_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; - } -} - -/// getExitBlocks - Return all of the successor blocks of this loop. These -/// are the blocks _outside of the current loop_ which are branched to. -/// -void Loop::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()); - - for (std::vector::const_iterator BI = Blocks.begin(), - BE = Blocks.end(); BI != BE; ++BI) - for (succ_iterator I = succ_begin(*BI), E = succ_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); -} - -/// 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 Loop::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 (std::vector::const_iterator BI = Blocks.begin(), - BE = Blocks.end(); BI != BE; ++BI) { - - BasicBlock *current = *BI; - switchExitBlocks.clear(); - - for (succ_iterator I = succ_begin(*BI), E = succ_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; - - pred_iterator PI = pred_begin(*I); - BasicBlock *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 (current->getTerminator()->getNumSuccessors() <= 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); - } - } - } -} - - -/// getLoopPreheader - If there is a preheader for this loop, return it. A -/// loop has a preheader if there is only one edge to the header of the loop -/// from outside of the loop. If this is the case, the block branching to the -/// header of the loop is the preheader node. -/// -/// This method returns null if there is no preheader for the loop. -/// -BasicBlock *Loop::getLoopPreheader() const { - // Keep track of nodes outside the loop branching to the header... - BasicBlock *Out = 0; - - // Loop over the predecessors of the header node... - BasicBlock *Header = getHeader(); - for (pred_iterator PI = pred_begin(Header), PE = pred_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?"); - succ_iterator SI = succ_begin(Out); - ++SI; - if (SI != succ_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. -BasicBlock *Loop::getLoopLatch() const { - BasicBlock *Header = getHeader(); - pred_iterator PI = pred_begin(Header), PE = pred_end(Header); - if (PI == PE) return 0; // no preds? - - BasicBlock *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; -} - -/// 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 *Loop::getCanonicalInductionVariable() const { - BasicBlock *H = getHeader(); - - BasicBlock *Incoming = 0, *Backedge = 0; - pred_iterator PI = pred_begin(H); - assert(PI != pred_end(H) && "Loop must have at least one backedge!"); - Backedge = *PI++; - if (PI == pred_end(H)) return 0; // dead loop - Incoming = *PI++; - if (PI != pred_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 (BasicBlock::iterator I = H->begin(); isa(I); ++I) { - PHINode *PN = cast(I); - 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. -/// -Instruction *Loop::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. -/// -Value *Loop::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)); - - BasicBlock *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); - } - } - } - - return 0; -} - -/// isLCSSAForm - Return true if the Loop is in LCSSA form -bool Loop::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) { - BasicBlock *BB = *BI; - for (BasicBlock::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) { - BasicBlock *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; -} - -//===-------------------------------------------------------------------===// -// APIs for updating loop information after changing the CFG -// - -/// addBasicBlockToLoop - This function is used by other analyses to update loop -/// information. NewBB is set to be a new member of the current loop. Because -/// of this, it is added as a member of all parent loops, and is added to the -/// specified LoopInfo object as being in the current basic block. It is not -/// valid to replace the loop header with this method. -/// -void Loop::addBasicBlockToLoop(BasicBlock *NewBB, LoopInfo &LI) { - assert((Blocks.empty() || LI[getHeader()] == this) && - "Incorrect LI specified for this loop!"); - assert(NewBB && "Cannot add a null basic block to the loop!"); - assert(LI[NewBB] == 0 && "BasicBlock already in the loop!"); - - // Add the loop mapping to the LoopInfo object... - LI.BBMap[NewBB] = this; - - // Add the basic block to this loop and all parent loops... - Loop *L = this; - while (L) { - L->Blocks.push_back(NewBB); - L = L->getParentLoop(); - } -} - -/// replaceChildLoopWith - This is used when splitting loops up. It replaces -/// the OldChild entry in our children list with NewChild, and updates the -/// parent pointers of the two loops as appropriate. -void Loop::replaceChildLoopWith(Loop *OldChild, Loop *NewChild) { - assert(OldChild->ParentLoop == this && "This loop is already broken!"); - assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); - 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; -} - -/// addChildLoop - Add the specified loop to be a child of this loop. -/// -void Loop::addChildLoop(Loop *NewChild) { - assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); - NewChild->ParentLoop = this; - SubLoops.push_back(NewChild); -} - -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); -} - -/// 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 *Loop::removeChildLoop(iterator I) { - assert(I != SubLoops.end() && "Cannot remove end iterator!"); - Loop *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; -} - - -/// removeBlockFromLoop - This removes the specified basic block from the -/// current loop, updating the Blocks and ExitBlocks lists as appropriate. This -/// does not update the mapping in the LoopInfo class. -void Loop::removeBlockFromLoop(BasicBlock *BB) { - RemoveFromVector(Blocks, BB); -} - // Ensure this file gets linked when LoopInfo.h is used. DEFINING_FILE_FOR(LoopInfo)