//===- RegionInfo.h - SESE region analysis ----------------------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // Calculate a program structure tree built out of single entry single exit // regions. // The basic ideas are taken from "The Program Structure Tree - Richard Johnson, // David Pearson, Keshav Pingali - 1994", however enriched with ideas from "The // Refined Process Structure Tree - Jussi Vanhatalo, Hagen Voelyer, Jana // Koehler - 2009". // The algorithm to calculate these data structures however is completely // different, as it takes advantage of existing information already available // in (Post)dominace tree and dominance frontier passes. This leads to a simpler // and in practice hopefully better performing algorithm. The runtime of the // algorithms described in the papers above are both linear in graph size, // O(V+E), whereas this algorithm is not, as the dominance frontier information // itself is not, but in practice runtime seems to be in the order of magnitude // of dominance tree calculation. // //===----------------------------------------------------------------------===// #ifndef LLVM_ANALYSIS_REGIONINFO_H #define LLVM_ANALYSIS_REGIONINFO_H #include "llvm/ADT/PointerIntPair.h" #include "llvm/Analysis/DominanceFrontier.h" #include "llvm/Analysis/PostDominators.h" #include "llvm/Support/Allocator.h" #include <map> namespace llvm { class Region; class RegionInfo; class raw_ostream; class Loop; class LoopInfo; /// @brief Marker class to iterate over the elements of a Region in flat mode. /// /// The class is used to either iterate in Flat mode or by not using it to not /// iterate in Flat mode. During a Flat mode iteration all Regions are entered /// and the iteration returns every BasicBlock. If the Flat mode is not /// selected for SubRegions just one RegionNode containing the subregion is /// returned. template <class GraphType> class FlatIt {}; /// @brief A RegionNode represents a subregion or a BasicBlock that is part of a /// Region. class RegionNode { RegionNode(const RegionNode &) LLVM_DELETED_FUNCTION; const RegionNode &operator=(const RegionNode &) LLVM_DELETED_FUNCTION; protected: /// This is the entry basic block that starts this region node. If this is a /// BasicBlock RegionNode, then entry is just the basic block, that this /// RegionNode represents. Otherwise it is the entry of this (Sub)RegionNode. /// /// In the BBtoRegionNode map of the parent of this node, BB will always map /// to this node no matter which kind of node this one is. /// /// The node can hold either a Region or a BasicBlock. /// Use one bit to save, if this RegionNode is a subregion or BasicBlock /// RegionNode. PointerIntPair<BasicBlock*, 1, bool> entry; /// @brief The parent Region of this RegionNode. /// @see getParent() Region* parent; public: /// @brief Create a RegionNode. /// /// @param Parent The parent of this RegionNode. /// @param Entry The entry BasicBlock of the RegionNode. If this /// RegionNode represents a BasicBlock, this is the /// BasicBlock itself. If it represents a subregion, this /// is the entry BasicBlock of the subregion. /// @param isSubRegion If this RegionNode represents a SubRegion. inline RegionNode(Region* Parent, BasicBlock* Entry, bool isSubRegion = 0) : entry(Entry, isSubRegion), parent(Parent) {} /// @brief Get the parent Region of this RegionNode. /// /// The parent Region is the Region this RegionNode belongs to. If for /// example a BasicBlock is element of two Regions, there exist two /// RegionNodes for this BasicBlock. Each with the getParent() function /// pointing to the Region this RegionNode belongs to. /// /// @return Get the parent Region of this RegionNode. inline Region* getParent() const { return parent; } /// @brief Get the entry BasicBlock of this RegionNode. /// /// If this RegionNode represents a BasicBlock this is just the BasicBlock /// itself, otherwise we return the entry BasicBlock of the Subregion /// /// @return The entry BasicBlock of this RegionNode. inline BasicBlock* getEntry() const { return entry.getPointer(); } /// @brief Get the content of this RegionNode. /// /// This can be either a BasicBlock or a subregion. Before calling getNodeAs() /// check the type of the content with the isSubRegion() function call. /// /// @return The content of this RegionNode. template<class T> inline T* getNodeAs() const; /// @brief Is this RegionNode a subregion? /// /// @return True if it contains a subregion. False if it contains a /// BasicBlock. inline bool isSubRegion() const { return entry.getInt(); } }; /// Print a RegionNode. inline raw_ostream &operator<<(raw_ostream &OS, const RegionNode &Node); template<> inline BasicBlock* RegionNode::getNodeAs<BasicBlock>() const { assert(!isSubRegion() && "This is not a BasicBlock RegionNode!"); return getEntry(); } template<> inline Region* RegionNode::getNodeAs<Region>() const { assert(isSubRegion() && "This is not a subregion RegionNode!"); return reinterpret_cast<Region*>(const_cast<RegionNode*>(this)); } //===----------------------------------------------------------------------===// /// @brief A single entry single exit Region. /// /// A Region is a connected subgraph of a control flow graph that has exactly /// two connections to the remaining graph. It can be used to analyze or /// optimize parts of the control flow graph. /// /// A <em> simple Region </em> is connected to the remaining graph by just two /// edges. One edge entering the Region and another one leaving the Region. /// /// An <em> extended Region </em> (or just Region) is a subgraph that can be /// transform into a simple Region. The transformation is done by adding /// BasicBlocks that merge several entry or exit edges so that after the merge /// just one entry and one exit edge exists. /// /// The \e Entry of a Region is the first BasicBlock that is passed after /// entering the Region. It is an element of the Region. The entry BasicBlock /// dominates all BasicBlocks in the Region. /// /// The \e Exit of a Region is the first BasicBlock that is passed after /// leaving the Region. It is not an element of the Region. The exit BasicBlock, /// postdominates all BasicBlocks in the Region. /// /// A <em> canonical Region </em> cannot be constructed by combining smaller /// Regions. /// /// Region A is the \e parent of Region B, if B is completely contained in A. /// /// Two canonical Regions either do not intersect at all or one is /// the parent of the other. /// /// The <em> Program Structure Tree</em> is a graph (V, E) where V is the set of /// Regions in the control flow graph and E is the \e parent relation of these /// Regions. /// /// Example: /// /// \verbatim /// A simple control flow graph, that contains two regions. /// /// 1 /// / | /// 2 | /// / \ 3 /// 4 5 | /// | | | /// 6 7 8 /// \ | / /// \ |/ Region A: 1 -> 9 {1,2,3,4,5,6,7,8} /// 9 Region B: 2 -> 9 {2,4,5,6,7} /// \endverbatim /// /// You can obtain more examples by either calling /// /// <tt> "opt -regions -analyze anyprogram.ll" </tt> /// or /// <tt> "opt -view-regions-only anyprogram.ll" </tt> /// /// on any LLVM file you are interested in. /// /// The first call returns a textual representation of the program structure /// tree, the second one creates a graphical representation using graphviz. class Region : public RegionNode { friend class RegionInfo; Region(const Region &) LLVM_DELETED_FUNCTION; const Region &operator=(const Region &) LLVM_DELETED_FUNCTION; // Information necessary to manage this Region. RegionInfo* RI; DominatorTree *DT; // The exit BasicBlock of this region. // (The entry BasicBlock is part of RegionNode) BasicBlock *exit; typedef std::vector<Region*> RegionSet; // The subregions of this region. RegionSet children; typedef std::map<BasicBlock*, RegionNode*> BBNodeMapT; // Save the BasicBlock RegionNodes that are element of this Region. mutable BBNodeMapT BBNodeMap; /// verifyBBInRegion - Check if a BB is in this Region. This check also works /// if the region is incorrectly built. (EXPENSIVE!) void verifyBBInRegion(BasicBlock* BB) const; /// verifyWalk - Walk over all the BBs of the region starting from BB and /// verify that all reachable basic blocks are elements of the region. /// (EXPENSIVE!) void verifyWalk(BasicBlock* BB, std::set<BasicBlock*>* visitedBB) const; /// verifyRegionNest - Verify if the region and its children are valid /// regions (EXPENSIVE!) void verifyRegionNest() const; public: /// @brief Create a new region. /// /// @param Entry The entry basic block of the region. /// @param Exit The exit basic block of the region. /// @param RI The region info object that is managing this region. /// @param DT The dominator tree of the current function. /// @param Parent The surrounding region or NULL if this is a top level /// region. Region(BasicBlock *Entry, BasicBlock *Exit, RegionInfo* RI, DominatorTree *DT, Region *Parent = 0); /// Delete the Region and all its subregions. ~Region(); /// @brief Get the entry BasicBlock of the Region. /// @return The entry BasicBlock of the region. BasicBlock *getEntry() const { return RegionNode::getEntry(); } /// @brief Replace the entry basic block of the region with the new basic /// block. /// /// @param BB The new entry basic block of the region. void replaceEntry(BasicBlock *BB); /// @brief Replace the exit basic block of the region with the new basic /// block. /// /// @param BB The new exit basic block of the region. void replaceExit(BasicBlock *BB); /// @brief Recursively replace the entry basic block of the region. /// /// This function replaces the entry basic block with a new basic block. It /// also updates all child regions that have the same entry basic block as /// this region. /// /// @param NewEntry The new entry basic block. void replaceEntryRecursive(BasicBlock *NewEntry); /// @brief Recursively replace the exit basic block of the region. /// /// This function replaces the exit basic block with a new basic block. It /// also updates all child regions that have the same exit basic block as /// this region. /// /// @param NewExit The new exit basic block. void replaceExitRecursive(BasicBlock *NewExit); /// @brief Get the exit BasicBlock of the Region. /// @return The exit BasicBlock of the Region, NULL if this is the TopLevel /// Region. BasicBlock *getExit() const { return exit; } /// @brief Get the parent of the Region. /// @return The parent of the Region or NULL if this is a top level /// Region. Region *getParent() const { return RegionNode::getParent(); } /// @brief Get the RegionNode representing the current Region. /// @return The RegionNode representing the current Region. RegionNode* getNode() const { return const_cast<RegionNode*>(reinterpret_cast<const RegionNode*>(this)); } /// @brief Get the nesting level of this Region. /// /// An toplevel Region has depth 0. /// /// @return The depth of the region. unsigned getDepth() const; /// @brief Check if a Region is the TopLevel region. /// /// The toplevel region represents the whole function. bool isTopLevelRegion() const { return exit == NULL; } /// @brief Return a new (non-canonical) region, that is obtained by joining /// this region with its predecessors. /// /// @return A region also starting at getEntry(), but reaching to the next /// basic block that forms with getEntry() a (non-canonical) region. /// NULL if such a basic block does not exist. Region *getExpandedRegion() const; /// @brief Return the first block of this region's single entry edge, /// if existing. /// /// @return The BasicBlock starting this region's single entry edge, /// else NULL. BasicBlock *getEnteringBlock() const; /// @brief Return the first block of this region's single exit edge, /// if existing. /// /// @return The BasicBlock starting this region's single exit edge, /// else NULL. BasicBlock *getExitingBlock() const; /// @brief Is this a simple region? /// /// A region is simple if it has exactly one exit and one entry edge. /// /// @return True if the Region is simple. bool isSimple() const; /// @brief Returns the name of the Region. /// @return The Name of the Region. std::string getNameStr() const; /// @brief Return the RegionInfo object, that belongs to this Region. RegionInfo *getRegionInfo() const { return RI; } /// PrintStyle - Print region in difference ways. enum PrintStyle { PrintNone, PrintBB, PrintRN }; /// @brief Print the region. /// /// @param OS The output stream the Region is printed to. /// @param printTree Print also the tree of subregions. /// @param level The indentation level used for printing. void print(raw_ostream& OS, bool printTree = true, unsigned level = 0, enum PrintStyle Style = PrintNone) const; /// @brief Print the region to stderr. void dump() const; /// @brief Check if the region contains a BasicBlock. /// /// @param BB The BasicBlock that might be contained in this Region. /// @return True if the block is contained in the region otherwise false. bool contains(const BasicBlock *BB) const; /// @brief Check if the region contains another region. /// /// @param SubRegion The region that might be contained in this Region. /// @return True if SubRegion is contained in the region otherwise false. bool contains(const Region *SubRegion) const { // Toplevel Region. if (!getExit()) return true; return contains(SubRegion->getEntry()) && (contains(SubRegion->getExit()) || SubRegion->getExit() == getExit()); } /// @brief Check if the region contains an Instruction. /// /// @param Inst The Instruction that might be contained in this region. /// @return True if the Instruction is contained in the region otherwise false. bool contains(const Instruction *Inst) const { return contains(Inst->getParent()); } /// @brief Check if the region contains a loop. /// /// @param L The loop that might be contained in this region. /// @return True if the loop is contained in the region otherwise false. /// In case a NULL pointer is passed to this function the result /// is false, except for the region that describes the whole function. /// In that case true is returned. bool contains(const Loop *L) const; /// @brief Get the outermost loop in the region that contains a loop. /// /// Find for a Loop L the outermost loop OuterL that is a parent loop of L /// and is itself contained in the region. /// /// @param L The loop the lookup is started. /// @return The outermost loop in the region, NULL if such a loop does not /// exist or if the region describes the whole function. Loop *outermostLoopInRegion(Loop *L) const; /// @brief Get the outermost loop in the region that contains a basic block. /// /// Find for a basic block BB the outermost loop L that contains BB and is /// itself contained in the region. /// /// @param LI A pointer to a LoopInfo analysis. /// @param BB The basic block surrounded by the loop. /// @return The outermost loop in the region, NULL if such a loop does not /// exist or if the region describes the whole function. Loop *outermostLoopInRegion(LoopInfo *LI, BasicBlock* BB) const; /// @brief Get the subregion that starts at a BasicBlock /// /// @param BB The BasicBlock the subregion should start. /// @return The Subregion if available, otherwise NULL. Region* getSubRegionNode(BasicBlock *BB) const; /// @brief Get the RegionNode for a BasicBlock /// /// @param BB The BasicBlock at which the RegionNode should start. /// @return If available, the RegionNode that represents the subregion /// starting at BB. If no subregion starts at BB, the RegionNode /// representing BB. RegionNode* getNode(BasicBlock *BB) const; /// @brief Get the BasicBlock RegionNode for a BasicBlock /// /// @param BB The BasicBlock for which the RegionNode is requested. /// @return The RegionNode representing the BB. RegionNode* getBBNode(BasicBlock *BB) const; /// @brief Add a new subregion to this Region. /// /// @param SubRegion The new subregion that will be added. /// @param moveChildren Move the children of this region, that are also /// contained in SubRegion into SubRegion. void addSubRegion(Region *SubRegion, bool moveChildren = false); /// @brief Remove a subregion from this Region. /// /// The subregion is not deleted, as it will probably be inserted into another /// region. /// @param SubRegion The SubRegion that will be removed. Region *removeSubRegion(Region *SubRegion); /// @brief Move all direct child nodes of this Region to another Region. /// /// @param To The Region the child nodes will be transferred to. void transferChildrenTo(Region *To); /// @brief Verify if the region is a correct region. /// /// Check if this is a correctly build Region. This is an expensive check, as /// the complete CFG of the Region will be walked. void verifyRegion() const; /// @brief Clear the cache for BB RegionNodes. /// /// After calling this function the BasicBlock RegionNodes will be stored at /// different memory locations. RegionNodes obtained before this function is /// called are therefore not comparable to RegionNodes abtained afterwords. void clearNodeCache(); /// @name Subregion Iterators /// /// These iterators iterator over all subregions of this Region. //@{ typedef RegionSet::iterator iterator; typedef RegionSet::const_iterator const_iterator; iterator begin() { return children.begin(); } iterator end() { return children.end(); } const_iterator begin() const { return children.begin(); } const_iterator end() const { return children.end(); } //@} /// @name BasicBlock Iterators /// /// These iterators iterate over all BasicBlocks that are contained in this /// Region. The iterator also iterates over BasicBlocks that are elements of /// a subregion of this Region. It is therefore called a flat iterator. //@{ template <bool IsConst> class block_iterator_wrapper : public df_iterator<typename conditional<IsConst, const BasicBlock, BasicBlock>::type*> { typedef df_iterator<typename conditional<IsConst, const BasicBlock, BasicBlock>::type*> super; public: typedef block_iterator_wrapper<IsConst> Self; typedef typename super::pointer pointer; // Construct the begin iterator. block_iterator_wrapper(pointer Entry, pointer Exit) : super(df_begin(Entry)) { // Mark the exit of the region as visited, so that the children of the // exit and the exit itself, i.e. the block outside the region will never // be visited. super::Visited.insert(Exit); } // Construct the end iterator. block_iterator_wrapper() : super(df_end<pointer>((BasicBlock *)0)) {} /*implicit*/ block_iterator_wrapper(super I) : super(I) {} // FIXME: Even a const_iterator returns a non-const BasicBlock pointer. // This was introduced for backwards compatibility, but should // be removed as soon as all users are fixed. BasicBlock *operator*() const { return const_cast<BasicBlock*>(super::operator*()); } }; typedef block_iterator_wrapper<false> block_iterator; typedef block_iterator_wrapper<true> const_block_iterator; block_iterator block_begin() { return block_iterator(getEntry(), getExit()); } block_iterator block_end() { return block_iterator(); } const_block_iterator block_begin() const { return const_block_iterator(getEntry(), getExit()); } const_block_iterator block_end() const { return const_block_iterator(); } //@} /// @name Element Iterators /// /// These iterators iterate over all BasicBlock and subregion RegionNodes that /// are direct children of this Region. It does not iterate over any /// RegionNodes that are also element of a subregion of this Region. //@{ typedef df_iterator<RegionNode*, SmallPtrSet<RegionNode*, 8>, false, GraphTraits<RegionNode*> > element_iterator; typedef df_iterator<const RegionNode*, SmallPtrSet<const RegionNode*, 8>, false, GraphTraits<const RegionNode*> > const_element_iterator; element_iterator element_begin(); element_iterator element_end(); const_element_iterator element_begin() const; const_element_iterator element_end() const; //@} }; //===----------------------------------------------------------------------===// /// @brief Analysis that detects all canonical Regions. /// /// The RegionInfo pass detects all canonical regions in a function. The Regions /// are connected using the parent relation. This builds a Program Structure /// Tree. class RegionInfo : public FunctionPass { typedef DenseMap<BasicBlock*,BasicBlock*> BBtoBBMap; typedef DenseMap<BasicBlock*, Region*> BBtoRegionMap; typedef SmallPtrSet<Region*, 4> RegionSet; RegionInfo(const RegionInfo &) LLVM_DELETED_FUNCTION; const RegionInfo &operator=(const RegionInfo &) LLVM_DELETED_FUNCTION; DominatorTree *DT; PostDominatorTree *PDT; DominanceFrontier *DF; /// The top level region. Region *TopLevelRegion; /// Map every BB to the smallest region, that contains BB. BBtoRegionMap BBtoRegion; // isCommonDomFrontier - Returns true if BB is in the dominance frontier of // entry, because it was inherited from exit. In the other case there is an // edge going from entry to BB without passing exit. bool isCommonDomFrontier(BasicBlock* BB, BasicBlock* entry, BasicBlock* exit) const; // isRegion - Check if entry and exit surround a valid region, based on // dominance tree and dominance frontier. bool isRegion(BasicBlock* entry, BasicBlock* exit) const; // insertShortCut - Saves a shortcut pointing from entry to exit. // This function may extend this shortcut if possible. void insertShortCut(BasicBlock* entry, BasicBlock* exit, BBtoBBMap* ShortCut) const; // getNextPostDom - Returns the next BB that postdominates N, while skipping // all post dominators that cannot finish a canonical region. DomTreeNode *getNextPostDom(DomTreeNode* N, BBtoBBMap *ShortCut) const; // isTrivialRegion - A region is trivial, if it contains only one BB. bool isTrivialRegion(BasicBlock *entry, BasicBlock *exit) const; // createRegion - Creates a single entry single exit region. Region *createRegion(BasicBlock *entry, BasicBlock *exit); // findRegionsWithEntry - Detect all regions starting with bb 'entry'. void findRegionsWithEntry(BasicBlock *entry, BBtoBBMap *ShortCut); // scanForRegions - Detects regions in F. void scanForRegions(Function &F, BBtoBBMap *ShortCut); // getTopMostParent - Get the top most parent with the same entry block. Region *getTopMostParent(Region *region); // buildRegionsTree - build the region hierarchy after all region detected. void buildRegionsTree(DomTreeNode *N, Region *region); // Calculate - detecte all regions in function and build the region tree. void Calculate(Function& F); void releaseMemory(); // updateStatistics - Update statistic about created regions. void updateStatistics(Region *R); // isSimple - Check if a region is a simple region with exactly one entry // edge and exactly one exit edge. bool isSimple(Region* R) const; public: static char ID; explicit RegionInfo(); ~RegionInfo(); /// @name FunctionPass interface //@{ virtual bool runOnFunction(Function &F); virtual void getAnalysisUsage(AnalysisUsage &AU) const; virtual void print(raw_ostream &OS, const Module *) const; virtual void verifyAnalysis() const; //@} /// @brief Get the smallest region that contains a BasicBlock. /// /// @param BB The basic block. /// @return The smallest region, that contains BB or NULL, if there is no /// region containing BB. Region *getRegionFor(BasicBlock *BB) const; /// @brief Set the smallest region that surrounds a basic block. /// /// @param BB The basic block surrounded by a region. /// @param R The smallest region that surrounds BB. void setRegionFor(BasicBlock *BB, Region *R); /// @brief A shortcut for getRegionFor(). /// /// @param BB The basic block. /// @return The smallest region, that contains BB or NULL, if there is no /// region containing BB. Region *operator[](BasicBlock *BB) const; /// @brief Return the exit of the maximal refined region, that starts at a /// BasicBlock. /// /// @param BB The BasicBlock the refined region starts. BasicBlock *getMaxRegionExit(BasicBlock *BB) const; /// @brief Find the smallest region that contains two regions. /// /// @param A The first region. /// @param B The second region. /// @return The smallest region containing A and B. Region *getCommonRegion(Region* A, Region *B) const; /// @brief Find the smallest region that contains two basic blocks. /// /// @param A The first basic block. /// @param B The second basic block. /// @return The smallest region that contains A and B. Region* getCommonRegion(BasicBlock* A, BasicBlock *B) const { return getCommonRegion(getRegionFor(A), getRegionFor(B)); } /// @brief Find the smallest region that contains a set of regions. /// /// @param Regions A vector of regions. /// @return The smallest region that contains all regions in Regions. Region* getCommonRegion(SmallVectorImpl<Region*> &Regions) const; /// @brief Find the smallest region that contains a set of basic blocks. /// /// @param BBs A vector of basic blocks. /// @return The smallest region that contains all basic blocks in BBS. Region* getCommonRegion(SmallVectorImpl<BasicBlock*> &BBs) const; Region *getTopLevelRegion() const { return TopLevelRegion; } /// @brief Update RegionInfo after a basic block was split. /// /// @param NewBB The basic block that was created before OldBB. /// @param OldBB The old basic block. void splitBlock(BasicBlock* NewBB, BasicBlock *OldBB); /// @brief Clear the Node Cache for all Regions. /// /// @see Region::clearNodeCache() void clearNodeCache() { if (TopLevelRegion) TopLevelRegion->clearNodeCache(); } }; inline raw_ostream &operator<<(raw_ostream &OS, const RegionNode &Node) { if (Node.isSubRegion()) return OS << Node.getNodeAs<Region>()->getNameStr(); else return OS << Node.getNodeAs<BasicBlock>()->getName(); } } // End llvm namespace #endif