X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=include%2Fllvm%2FAnalysis%2FLoopInfo.h;h=a2bd6574e615b585ab5a0a350d76e0df7752bf22;hp=4921629a040de72713013f8c8afe9fad7040ff8b;hb=fbbc16fa87defddc1d6eecb56e609a8ae6438ed1;hpb=092c5ccf5bdcaa53151645e5628cec77fcf4062b diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h index 4921629a040..a2bd6574e61 100644 --- a/include/llvm/Analysis/LoopInfo.h +++ b/include/llvm/Analysis/LoopInfo.h @@ -27,35 +27,34 @@ // //===----------------------------------------------------------------------===// -#ifndef LLVM_ANALYSIS_LOOP_INFO_H -#define LLVM_ANALYSIS_LOOP_INFO_H +#ifndef LLVM_ANALYSIS_LOOPINFO_H +#define LLVM_ANALYSIS_LOOPINFO_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/SmallPtrSet.h" #include "llvm/ADT/SmallVector.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/Analysis/Dominators.h" -#include "llvm/Support/CFG.h" -#include "llvm/Support/raw_ostream.h" +#include "llvm/IR/CFG.h" +#include "llvm/IR/Instruction.h" +#include "llvm/IR/Instructions.h" +#include "llvm/Pass.h" #include -#include namespace llvm { -template -static void RemoveFromVector(std::vector &V, T *N) { - typename std::vector::iterator I = std::find(V.begin(), V.end(), N); - assert(I != V.end() && "N is not in this list!"); - V.erase(I); -} +// FIXME: Replace this brittle forward declaration with the include of the new +// PassManager.h when doing so doesn't break the PassManagerBuilder. +template class AnalysisManager; +class PreservedAnalyses; class DominatorTree; class LoopInfo; class Loop; +class MDNode; class PHINode; +class raw_ostream; +template class DominatorTreeBase; template class LoopInfoBase; template class LoopBase; @@ -72,13 +71,17 @@ 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 &); + SmallPtrSet DenseBlockSet; + + /// Indicator that this loop is no longer a valid loop. + bool IsInvalid = false; + + LoopBase(const LoopBase &) = delete; + const LoopBase& + operator=(const LoopBase &) = delete; public: /// Loop ctor - This creates an empty loop. - LoopBase() : ParentLoop(0) {} + LoopBase() : ParentLoop(nullptr) {} ~LoopBase() { for (size_t i = 0, e = SubLoops.size(); i != e; ++i) delete SubLoops[i]; @@ -97,19 +100,22 @@ public: BlockT *getHeader() const { return Blocks.front(); } LoopT *getParentLoop() const { return ParentLoop; } + /// setParentLoop is a raw interface for bypassing addChildLoop. + void setParentLoop(LoopT *L) { ParentLoop = L; } + /// contains - Return true if the specified loop is contained within in /// this loop. /// bool contains(const LoopT *L) const { if (L == this) return true; - if (L == 0) return false; + if (!L) return false; return contains(L->getParentLoop()); } /// contains - Return true if the specified basic block is in this loop. /// bool contains(const BlockT *BB) const { - return std::find(block_begin(), block_end(), BB) != block_end(); + return DenseBlockSet.count(BB); } /// contains - Return true if the specified instruction is in this loop. @@ -122,9 +128,14 @@ public: /// 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. @@ -133,20 +144,29 @@ public: typedef typename std::vector::const_iterator block_iterator; block_iterator block_begin() const { return Blocks.begin(); } block_iterator block_end() const { return Blocks.end(); } + inline iterator_range blocks() const { + return make_range(block_begin(), block_end()); + } /// getNumBlocks - Get the number of blocks in this loop in constant time. unsigned getNumBlocks() const { return Blocks.size(); } + /// Invalidate the loop, indicating that it is no longer a loop. + void invalidate() { IsInvalid = true; } + + /// Return true if this loop is no longer valid. + bool isInvalid() { return IsInvalid; } + /// isLoopExiting - True if terminator in the block can branch to another /// block that is outside of the current loop. /// bool isLoopExiting(const BlockT *BB) const { - typedef GraphTraits BlockTraits; + typedef GraphTraits BlockTraits; for (typename BlockTraits::ChildIteratorType SI = - BlockTraits::child_begin(const_cast(BB)), - SE = BlockTraits::child_end(const_cast(BB)); SI != SE; ++SI) { + BlockTraits::child_begin(BB), + SE = BlockTraits::child_end(BB); SI != SE; ++SI) { if (!contains(*SI)) return true; } @@ -161,8 +181,8 @@ public: typedef GraphTraits > InvBlockTraits; for (typename InvBlockTraits::ChildIteratorType I = - InvBlockTraits::child_begin(const_cast(H)), - E = InvBlockTraits::child_end(const_cast(H)); I != E; ++I) + InvBlockTraits::child_begin(H), + E = InvBlockTraits::child_end(H); I != E; ++I) if (contains(*I)) ++NumBackEdges; @@ -181,83 +201,26 @@ 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; /// Edge type. - typedef std::pair Edge; + typedef std::pair Edge; /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). - template - 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()); - array_pod_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. - ExitEdges.push_back(EdgeT(*BI, *I)); - } + 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 @@ -266,70 +229,29 @@ 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 = getLoopPredecessor(); - if (!Out) return 0; - - // Make sure there is only one exit out of the preheader. - typedef GraphTraits BlockTraits; - 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. - - // The predecessor has exactly one successor, so it is a preheader. - return Out; - } + BlockT *getLoopPreheader() const; /// getLoopPredecessor - If the given loop's header has exactly one unique /// predecessor outside the loop, return it. Otherwise return null. /// This is less strict that the loop "preheader" concept, which requires /// the predecessor to have exactly one successor. /// - BlockT *getLoopPredecessor() const { - // 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) { - typename InvBlockTraits::NodeType *N = *PI; - if (!contains(N)) { // If the block is not in the loop... - if (Out && Out != N) - return 0; // Multiple predecessors outside the loop - Out = N; - } - } - - // Make sure there is only one exit out of the preheader. - assert(Out && "Header of loop has no predecessors from outside loop?"); - return Out; - } + BlockT *getLoopPredecessor() const; /// getLoopLatch - If there is a single latch block for this loop, return it. /// A latch block is a block that contains a branch back to the header. - BlockT *getLoopLatch() const { - BlockT *Header = getHeader(); - typedef GraphTraits > InvBlockTraits; - typename InvBlockTraits::ChildIteratorType PI = - InvBlockTraits::child_begin(Header); - typename InvBlockTraits::ChildIteratorType PE = - InvBlockTraits::child_end(Header); - BlockT *Latch = 0; - for (; PI != PE; ++PI) { - typename InvBlockTraits::NodeType *N = *PI; - if (contains(N)) { - if (Latch) return 0; - Latch = N; - } - } + BlockT *getLoopLatch() const; - return Latch; + /// getLoopLatches - Return all loop latch blocks of this loop. A latch block + /// is a block that contains a branch back to the header. + void getLoopLatches(SmallVectorImpl &LoopLatches) const { + BlockT *H = getHeader(); + typedef GraphTraits > InvBlockTraits; + for (typename InvBlockTraits::ChildIteratorType I = + InvBlockTraits::child_begin(H), + E = InvBlockTraits::child_end(H); I != E; ++I) + if (contains(*I)) + LoopLatches.push_back(*I); } //===--------------------------------------------------------------------===// @@ -348,23 +270,13 @@ 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. /// void addChildLoop(LoopT *NewChild) { - assert(NewChild->ParentLoop == 0 && "NewChild already has a parent!"); + assert(!NewChild->ParentLoop && "NewChild already has a parent!"); NewChild->ParentLoop = static_cast(this); SubLoops.push_back(NewChild); } @@ -377,7 +289,7 @@ public: LoopT *Child = *I; assert(Child->ParentLoop == this && "Child is not a child of this loop!"); SubLoops.erase(SubLoops.begin()+(I-begin())); - Child->ParentLoop = 0; + Child->ParentLoop = nullptr; return Child; } @@ -386,6 +298,17 @@ public: /// transformations should use addBasicBlockToLoop. void addBlockEntry(BlockT *BB) { Blocks.push_back(BB); + DenseBlockSet.insert(BB); + } + + /// reverseBlocks - interface to reverse Blocks[from, end of loop] in this loop + void reverseBlock(unsigned from) { + std::reverse(Blocks.begin() + from, Blocks.end()); + } + + /// reserveBlocks- interface to do reserve() for Blocks + void reserveBlocks(unsigned size) { + Blocks.reserve(size); } /// moveToHeader - This method is used to move BB (which must be part of this @@ -407,130 +330,26 @@ public: /// current loop, updating the Blocks as appropriate. This does not update /// the mapping in the LoopInfo class. void removeBlockFromLoop(BlockT *BB) { - RemoveFromVector(Blocks, BB); + auto I = std::find(Blocks.begin(), Blocks.end(), BB); + assert(I != Blocks.end() && "N is not in this list!"); + Blocks.erase(I); + + DenseBlockSet.erase(BB); } /// verifyLoop - Verify loop structure - void verifyLoop() const { -#ifndef NDEBUG - assert(!Blocks.empty() && "Loop header is missing"); - - // Setup for using a depth-first iterator to visit every block in the loop. - SmallVector ExitBBs; - getExitBlocks(ExitBBs); - llvm::SmallPtrSet VisitSet; - VisitSet.insert(ExitBBs.begin(), ExitBBs.end()); - df_ext_iterator > - BI = df_ext_begin(getHeader(), VisitSet), - BE = df_ext_end(getHeader(), VisitSet); - - // Keep track of the number of BBs visited. - unsigned NumVisited = 0; - - // 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 ( ; BI != BE; ++BI) { - BlockT *BB = *BI; - 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) { - BlockT *N = *PI; - if (std::binary_search(LoopBBs.begin(), LoopBBs.end(), N)) - HasInsideLoopPreds = true; - else - OutsideLoopPreds.push_back(N); - } - - 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!"); - - NumVisited++; - } - - assert(NumVisited == getNumBlocks() && "Unreachable block in loop"); - - // 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(DenseSet *Loops) const { - Loops->insert(static_cast(this)); - // Verify this loop. - verifyLoop(); - // Verify the subloops. - for (iterator I = begin(), E = end(); I != E; ++I) - (*I)->verifyLoopNest(Loops); - } + 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 (isLoopExiting(BB)) OS << ""; - } - OS << "\n"; - - for (iterator I = begin(), E = end(); I != E; ++I) - (*I)->print(OS, Depth+2); - } + void print(raw_ostream &OS, unsigned Depth = 0) const; protected: friend class LoopInfoBase; - explicit LoopBase(BlockT *BB) : ParentLoop(0) { + explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) { Blocks.push_back(BB); + DenseBlockSet.insert(BB); } }; @@ -540,17 +359,20 @@ raw_ostream& operator<<(raw_ostream &OS, const LoopBase &Loop) { return OS; } +// Implementation in LoopInfoImpl.h +extern template class LoopBase; + class Loop : public LoopBase { public: Loop() {} /// isLoopInvariant - Return true if the specified value is loop invariant /// - bool isLoopInvariant(Value *V) const; + bool isLoopInvariant(const Value *V) const; /// hasLoopInvariantOperands - Return true if all the operands of the /// specified instruction are loop invariant. - bool hasLoopInvariantOperands(Instruction *I) const; + bool hasLoopInvariantOperands(const 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. @@ -562,7 +384,7 @@ public: /// If null, the terminator of the loop preheader is used. /// bool makeLoopInvariant(Value *V, bool &Changed, - Instruction *InsertPt = 0) const; + Instruction *InsertPt = nullptr) const; /// makeLoopInvariant - If the given instruction is inside of the /// loop and it can be hoisted, do so to make it trivially loop-invariant. @@ -574,7 +396,7 @@ public: /// If null, the terminator of the loop preheader is used. /// bool makeLoopInvariant(Instruction *I, bool &Changed, - Instruction *InsertPt = 0) const; + Instruction *InsertPt = nullptr) const; /// getCanonicalInductionVariable - Check to see if the loop has a canonical /// induction variable: an integer recurrence that starts at 0 and increments @@ -589,11 +411,47 @@ public: /// isLCSSAForm - Return true if the Loop is in LCSSA form bool isLCSSAForm(DominatorTree &DT) const; + /// \brief Return true if this Loop and all inner subloops are in LCSSA form. + bool isRecursivelyLCSSAForm(DominatorTree &DT) const; + /// isLoopSimplifyForm - Return true if the Loop is in the form that /// the LoopSimplify form transforms loops to, which is sometimes called /// normal form. bool isLoopSimplifyForm() const; + /// isSafeToClone - Return true if the loop body is safe to clone in practice. + bool isSafeToClone() const; + + /// Returns true if the loop is annotated parallel. + /// + /// A parallel loop can be assumed to not contain any dependencies between + /// iterations by the compiler. That is, any loop-carried dependency checking + /// can be skipped completely when parallelizing the loop on the target + /// machine. Thus, if the parallel loop information originates from the + /// programmer, e.g. via the OpenMP parallel for pragma, it is the + /// programmer's responsibility to ensure there are no loop-carried + /// dependencies. The final execution order of the instructions across + /// iterations is not guaranteed, thus, the end result might or might not + /// implement actual concurrent execution of instructions across multiple + /// iterations. + bool isAnnotatedParallel() const; + + /// Return the llvm.loop loop id metadata node for this loop if it is present. + /// + /// If this loop contains the same llvm.loop metadata on each branch to the + /// header then the node is returned. If any latch instruction does not + /// contain llvm.loop or or if multiple latches contain different nodes then + /// 0 is returned. + MDNode *getLoopID() const; + /// Set the llvm.loop loop id metadata for this loop. + /// + /// The LoopID metadata node will be added to each terminator instruction in + /// the loop that branches to the loop header. + /// + /// The LoopID metadata node should have one or more operands and the first + /// operand should should be the node itself. + void setLoopID(MDNode *LoopID) const; + /// hasDedicatedExits - Return true if no exit block for the loop /// has a predecessor that is outside the loop. bool hasDedicatedExits() const; @@ -610,6 +468,28 @@ public: void dump() const; + /// \brief Return the debug location of the start of this loop. + /// This looks for a BB terminating instruction with a known debug + /// location by looking at the preheader and header blocks. If it + /// cannot find a terminating instruction with location information, + /// it returns an unknown location. + DebugLoc getStartLoc() const { + BasicBlock *HeadBB; + + // Try the pre-header first. + if ((HeadBB = getLoopPreheader()) != nullptr) + if (DebugLoc DL = HeadBB->getTerminator()->getDebugLoc()) + return DL; + + // If we have no pre-header or there are no instructions with debug + // info in it, try the header. + HeadBB = getHeader(); + if (HeadBB) + return HeadBB->getTerminator()->getDebugLoc(); + + return DebugLoc(); + } + private: friend class LoopInfoBase; explicit Loop(BasicBlock *BB) : LoopBase(BB) {} @@ -623,40 +503,62 @@ private: template class LoopInfoBase { // BBMap - Mapping of basic blocks to the inner most loop they occur in - DenseMap BBMap; + DenseMap BBMap; std::vector TopLevelLoops; + std::vector RemovedLoops; + friend class LoopBase; friend class LoopInfo; - void operator=(const LoopInfoBase &); // do not implement - LoopInfoBase(const LoopInfo &); // do not implement + void operator=(const LoopInfoBase &) = delete; + LoopInfoBase(const LoopInfoBase &) = delete; public: LoopInfoBase() { } ~LoopInfoBase() { releaseMemory(); } + LoopInfoBase(LoopInfoBase &&Arg) + : BBMap(std::move(Arg.BBMap)), + TopLevelLoops(std::move(Arg.TopLevelLoops)) { + // We have to clear the arguments top level loops as we've taken ownership. + Arg.TopLevelLoops.clear(); + } + LoopInfoBase &operator=(LoopInfoBase &&RHS) { + BBMap = std::move(RHS.BBMap); + + for (auto *L : TopLevelLoops) + delete L; + TopLevelLoops = std::move(RHS.TopLevelLoops); + RHS.TopLevelLoops.clear(); + return *this; + } + void releaseMemory() { - for (typename std::vector::iterator I = - TopLevelLoops.begin(), E = TopLevelLoops.end(); I != E; ++I) - delete *I; // Delete all of the loops... + BBMap.clear(); - BBMap.clear(); // Reset internal state of analysis + for (auto *L : TopLevelLoops) + delete L; TopLevelLoops.clear(); + for (auto *L : RemovedLoops) + delete L; + RemovedLoops.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 { - return BBMap.lookup(const_cast(BB)); - } + LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); } /// operator[] - same as getLoopFor... /// @@ -673,7 +575,7 @@ public: } // isLoopHeader - True if the block is a loop header node - bool isLoopHeader(BlockT *BB) const { + bool isLoopHeader(const BlockT *BB) const { const LoopT *L = getLoopFor(BB); return L && L->getHeader() == BB; } @@ -684,7 +586,7 @@ public: LoopT *removeLoop(iterator I) { assert(I != end() && "Cannot remove end iterator!"); LoopT *L = *I; - assert(L->getParentLoop() == 0 && "Not a top-level loop!"); + assert(!L->getParentLoop() && "Not a top-level loop!"); TopLevelLoops.erase(TopLevelLoops.begin() + (I-begin())); return L; } @@ -704,18 +606,17 @@ public: /// list with the indicated loop. void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop) { - typename std::vector::iterator I = - std::find(TopLevelLoops.begin(), TopLevelLoops.end(), OldLoop); + auto 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 && + assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop && "Loops already embedded into a subloop!"); } /// addTopLevelLoop - This adds the specified loop to the collection of /// top-level loops. void addTopLevelLoop(LoopT *New) { - assert(New->getParentLoop() == 0 && "Loop already in subloop!"); + assert(!New->getParentLoop() && "Loop already in subloop!"); TopLevelLoops.push_back(New); } @@ -723,7 +624,7 @@ public: /// including all of the Loop objects it is nested in and our mapping from /// BasicBlocks to loops. void removeBlock(BlockT *BB) { - typename DenseMap::iterator I = BBMap.find(BB); + auto I = BBMap.find(BB); if (I != BBMap.end()) { for (LoopT *L = I->second; L; L = L->getParentLoop()) L->removeBlockFromLoop(BB); @@ -736,290 +637,47 @@ public: static bool isNotAlreadyContainedIn(const LoopT *SubLoop, const LoopT *ParentLoop) { - if (SubLoop == 0) return true; + if (!SubLoop) 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.count(BB)) 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) { - typename InvBlockTraits::NodeType *N = *I; - // If BB dominates its predecessor... - if (DT.dominates(BB, N) && DT.isReachableFromEntry(N)) - TodoStack.push_back(N); - } - - 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; - - 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.isReachableFromEntry(X)) { - // 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, f = SubLoop->Blocks.size(); j != f; ++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; - } + /// Create the loop forest using a stable algorithm. + void analyze(const DominatorTreeBase &DomTree); // Debugging + void print(raw_ostream &OS) const; - void print(raw_ostream &OS) const { - for (unsigned i = 0; i < TopLevelLoops.size(); ++i) - TopLevelLoops[i]->print(OS); - #if 0 - for (DenseMap::const_iterator I = BBMap.begin(), - E = BBMap.end(); I != E; ++I) - OS << "BB '" << I->first->getName() << "' level = " - << I->second->getLoopDepth() << "\n"; - #endif - } + void verify() const; }; -class LoopInfo : public FunctionPass { - LoopInfoBase LI; - friend class LoopBase; +// Implementation in LoopInfoImpl.h +extern template class LoopInfoBase; - void operator=(const LoopInfo &); // do not implement - LoopInfo(const LoopInfo &); // do not implement -public: - static char ID; // Pass identification, replacement for typeid - - LoopInfo() : FunctionPass(ID) { - initializeLoopInfoPass(*PassRegistry::getPassRegistry()); - } - - LoopInfoBase& getBase() { return LI; } - - /// iterator/begin/end - The interface to the top-level loops in the current - /// function. - /// - typedef LoopInfoBase::iterator iterator; - inline iterator begin() const { return LI.begin(); } - inline iterator end() const { return LI.end(); } - bool empty() const { return LI.empty(); } - - /// getLoopFor - Return the inner most loop that BB lives in. If a basic - /// block is in no loop (for example the entry node), null is returned. - /// - inline Loop *getLoopFor(const BasicBlock *BB) const { - return LI.getLoopFor(BB); - } - - /// operator[] - same as getLoopFor... - /// - inline const Loop *operator[](const BasicBlock *BB) const { - return LI.getLoopFor(BB); - } - - /// getLoopDepth - Return the loop nesting level of the specified block. A - /// depth of 0 means the block is not inside any loop. - /// - inline unsigned getLoopDepth(const BasicBlock *BB) const { - return LI.getLoopDepth(BB); - } - - // isLoopHeader - True if the block is a loop header node - inline bool isLoopHeader(BasicBlock *BB) const { - return LI.isLoopHeader(BB); - } - - /// runOnFunction - Calculate the natural loop information. - /// - virtual bool runOnFunction(Function &F); - - virtual void verifyAnalysis() const; - - virtual void releaseMemory() { LI.releaseMemory(); } - - virtual void print(raw_ostream &O, const Module* M = 0) const; - - virtual void getAnalysisUsage(AnalysisUsage &AU) const; +class LoopInfo : public LoopInfoBase { + typedef LoopInfoBase BaseT; - /// removeLoop - This removes the specified top-level loop from this loop info - /// object. The loop is not deleted, as it will presumably be inserted into - /// another loop. - inline Loop *removeLoop(iterator I) { return LI.removeLoop(I); } - - /// changeLoopFor - Change the top-level loop that contains BB to the - /// specified loop. This should be used by transformations that restructure - /// the loop hierarchy tree. - inline void changeLoopFor(BasicBlock *BB, Loop *L) { - LI.changeLoopFor(BB, L); - } + friend class LoopBase; - /// 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); - } + void operator=(const LoopInfo &) = delete; + LoopInfo(const LoopInfo &) = delete; +public: + LoopInfo() {} + explicit LoopInfo(const DominatorTreeBase &DomTree); - /// addTopLevelLoop - This adds the specified loop to the collection of - /// top-level loops. - inline void addTopLevelLoop(Loop *New) { - LI.addTopLevelLoop(New); + LoopInfo(LoopInfo &&Arg) : BaseT(std::move(static_cast(Arg))) {} + LoopInfo &operator=(LoopInfo &&RHS) { + BaseT::operator=(std::move(static_cast(RHS))); + return *this; } - /// 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); - } + // Most of the public interface is provided via LoopInfoBase. - /// 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); + /// Update LoopInfo after removing the last backedge from a loop. This updates + /// the loop forest and parent loops for each block so that \c L is no longer + /// referenced, but does not actually delete \c L immediately. The pointer + /// will remain valid until this LoopInfo's memory is released. + void markAsRemoved(Loop *L); /// replacementPreservesLCSSAForm - Returns true if replacing From with To /// everywhere is guaranteed to preserve LCSSA form. @@ -1041,8 +699,79 @@ public: // it as a replacement will not break LCSSA form. return ToLoop->contains(getLoopFor(From->getParent())); } -}; + /// \brief Checks if moving a specific instruction can break LCSSA in any + /// loop. + /// + /// Return true if moving \p Inst to before \p NewLoc will break LCSSA, + /// assuming that the function containing \p Inst and \p NewLoc is currently + /// in LCSSA form. + bool movementPreservesLCSSAForm(Instruction *Inst, Instruction *NewLoc) { + assert(Inst->getFunction() == NewLoc->getFunction() && + "Can't reason about IPO!"); + + auto *OldBB = Inst->getParent(); + auto *NewBB = NewLoc->getParent(); + + // Movement within the same loop does not break LCSSA (the equality check is + // to avoid doing a hashtable lookup in case of intra-block movement). + if (OldBB == NewBB) + return true; + + auto *OldLoop = getLoopFor(OldBB); + auto *NewLoop = getLoopFor(NewBB); + + if (OldLoop == NewLoop) + return true; + + // Check if Outer contains Inner; with the null loop counting as the + // "outermost" loop. + auto Contains = [](const Loop *Outer, const Loop *Inner) { + return !Outer || Outer->contains(Inner); + }; + + // To check that the movement of Inst to before NewLoc does not break LCSSA, + // we need to check two sets of uses for possible LCSSA violations at + // NewLoc: the users of NewInst, and the operands of NewInst. + + // If we know we're hoisting Inst out of an inner loop to an outer loop, + // then the uses *of* Inst don't need to be checked. + + if (!Contains(NewLoop, OldLoop)) { + for (Use &U : Inst->uses()) { + auto *UI = cast(U.getUser()); + auto *UBB = isa(UI) ? cast(UI)->getIncomingBlock(U) + : UI->getParent(); + if (UBB != NewBB && getLoopFor(UBB) != NewLoop) + return false; + } + } + + // If we know we're sinking Inst from an outer loop into an inner loop, then + // the *operands* of Inst don't need to be checked. + + if (!Contains(OldLoop, NewLoop)) { + // See below on why we can't handle phi nodes here. + if (isa(Inst)) + return false; + + for (Use &U : Inst->operands()) { + auto *DefI = dyn_cast(U.get()); + if (!DefI) + return false; + + // This would need adjustment if we allow Inst to be a phi node -- the + // new use block won't simply be NewBB. + + auto *DefBlock = DefI->getParent(); + if (DefBlock != NewBB && getLoopFor(DefBlock) != NewLoop) + return false; + } + } + + return true; + } +}; // Allow clients to walk the list of nested loops... template <> struct GraphTraits { @@ -1071,26 +800,71 @@ 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(); +/// \brief Analysis pass that exposes the \c LoopInfo for a function. +class LoopAnalysis { + static char PassID; + +public: + typedef LoopInfo Result; + + /// \brief Opaque, unique identifier for this analysis pass. + static void *ID() { return (void *)&PassID; } + + /// \brief Provide a name for the analysis for debugging and logging. + static StringRef name() { return "LoopAnalysis"; } + + LoopInfo run(Function &F, AnalysisManager *AM); +}; + +/// \brief Printer pass for the \c LoopAnalysis results. +class LoopPrinterPass { + raw_ostream &OS; + +public: + explicit LoopPrinterPass(raw_ostream &OS) : OS(OS) {} + PreservedAnalyses run(Function &F, AnalysisManager *AM); + + static StringRef name() { return "LoopPrinterPass"; } +}; + +/// \brief The legacy pass manager's analysis pass to compute loop information. +class LoopInfoWrapperPass : public FunctionPass { + LoopInfo LI; + +public: + static char ID; // Pass identification, replacement for typeid + + LoopInfoWrapperPass() : FunctionPass(ID) { + initializeLoopInfoWrapperPassPass(*PassRegistry::getPassRegistry()); } -} + + LoopInfo &getLoopInfo() { return LI; } + const LoopInfo &getLoopInfo() const { return LI; } + + /// \brief Calculate the natural loop information for a given function. + bool runOnFunction(Function &F) override; + + void verifyAnalysis() const override; + + void releaseMemory() override { LI.releaseMemory(); } + + void print(raw_ostream &O, const Module *M = nullptr) const override; + + void getAnalysisUsage(AnalysisUsage &AU) const override; +}; + +/// \brief Pass for printing a loop's contents as LLVM's text IR assembly. +class PrintLoopPass { + raw_ostream &OS; + std::string Banner; + +public: + PrintLoopPass(); + PrintLoopPass(raw_ostream &OS, const std::string &Banner = ""); + + PreservedAnalyses run(Loop &L); + static StringRef name() { return "PrintLoopPass"; } +}; } // End llvm namespace