RegionInfo.h revision 0e6fcf4be360f5d73685c213e3b4af1bb9ce2b5d
1//===- RegionInfo.h - SESE region analysis ----------------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// Calculate a program structure tree built out of single entry single exit 11// regions. 12// The basic ideas are taken from "The Program Structure Tree - Richard Johnson, 13// David Pearson, Keshav Pingali - 1994", however enriched with ideas from "The 14// Refined Process Structure Tree - Jussi Vanhatalo, Hagen Voelyer, Jana 15// Koehler - 2009". 16// The algorithm to calculate these data structures however is completely 17// different, as it takes advantage of existing information already available 18// in (Post)dominace tree and dominance frontier passes. This leads to a simpler 19// and in practice hopefully better performing algorithm. The runtime of the 20// algorithms described in the papers above are both linear in graph size, 21// O(V+E), whereas this algorithm is not, as the dominance frontier information 22// itself is not, but in practice runtime seems to be in the order of magnitude 23// of dominance tree calculation. 24// 25//===----------------------------------------------------------------------===// 26 27#ifndef LLVM_ANALYSIS_REGION_INFO_H 28#define LLVM_ANALYSIS_REGION_INFO_H 29 30#include "llvm/ADT/PointerIntPair.h" 31#include "llvm/Analysis/Dominators.h" 32#include "llvm/Analysis/PostDominators.h" 33#include "llvm/Support/Allocator.h" 34 35namespace llvm { 36 37class Region; 38class RegionInfo; 39class raw_ostream; 40class Loop; 41class LoopInfo; 42 43/// @brief Marker class to iterate over the elements of a Region in flat mode. 44/// 45/// The class is used to either iterate in Flat mode or by not using it to not 46/// iterate in Flat mode. During a Flat mode iteration all Regions are entered 47/// and the iteration returns every BasicBlock. If the Flat mode is not 48/// selected for SubRegions just one RegionNode containing the subregion is 49/// returned. 50template <class GraphType> 51class FlatIt {}; 52 53/// @brief A RegionNode represents a subregion or a BasicBlock that is part of a 54/// Region. 55class RegionNode { 56 // DO NOT IMPLEMENT 57 RegionNode(const RegionNode &); 58 // DO NOT IMPLEMENT 59 const RegionNode &operator=(const RegionNode &); 60 61 /// This is the entry basic block that starts this region node. If this is a 62 /// BasicBlock RegionNode, then entry is just the basic block, that this 63 /// RegionNode represents. Otherwise it is the entry of this (Sub)RegionNode. 64 /// 65 /// In the BBtoRegionNode map of the parent of this node, BB will always map 66 /// to this node no matter which kind of node this one is. 67 /// 68 /// The node can hold either a Region or a BasicBlock. 69 /// Use one bit to save, if this RegionNode is a subregion or BasicBlock 70 /// RegionNode. 71 PointerIntPair<BasicBlock*, 1, bool> entry; 72 73protected: 74 /// @brief The parent Region of this RegionNode. 75 /// @see getParent() 76 Region* parent; 77 78public: 79 /// @brief Create a RegionNode. 80 /// 81 /// @param Parent The parent of this RegionNode. 82 /// @param Entry The entry BasicBlock of the RegionNode. If this 83 /// RegionNode represents a BasicBlock, this is the 84 /// BasicBlock itself. If it represents a subregion, this 85 /// is the entry BasicBlock of the subregion. 86 /// @param isSubRegion If this RegionNode represents a SubRegion. 87 inline RegionNode(Region* Parent, BasicBlock* Entry, bool isSubRegion = 0) 88 : entry(Entry, isSubRegion), parent(Parent) {} 89 90 /// @brief Get the parent Region of this RegionNode. 91 /// 92 /// The parent Region is the Region this RegionNode belongs to. If for 93 /// example a BasicBlock is element of two Regions, there exist two 94 /// RegionNodes for this BasicBlock. Each with the getParent() function 95 /// pointing to the Region this RegionNode belongs to. 96 /// 97 /// @return Get the parent Region of this RegionNode. 98 inline Region* getParent() const { return parent; } 99 100 /// @brief Get the entry BasicBlock of this RegionNode. 101 /// 102 /// If this RegionNode represents a BasicBlock this is just the BasicBlock 103 /// itself, otherwise we return the entry BasicBlock of the Subregion 104 /// 105 /// @return The entry BasicBlock of this RegionNode. 106 inline BasicBlock* getEntry() const { return entry.getPointer(); } 107 108 /// @brief Get the content of this RegionNode. 109 /// 110 /// This can be either a BasicBlock or a subregion. Before calling getNodeAs() 111 /// check the type of the content with the isSubRegion() function call. 112 /// 113 /// @return The content of this RegionNode. 114 template<class T> 115 inline T* getNodeAs() const; 116 117 /// @brief Is this RegionNode a subregion? 118 /// 119 /// @return True if it contains a subregion. False if it contains a 120 /// BasicBlock. 121 inline bool isSubRegion() const { 122 return entry.getInt(); 123 } 124}; 125 126/// Print a RegionNode. 127inline raw_ostream &operator<<(raw_ostream &OS, const RegionNode &Node); 128 129template<> 130inline BasicBlock* RegionNode::getNodeAs<BasicBlock>() const { 131 assert(!isSubRegion() && "This is not a BasicBlock RegionNode!"); 132 return getEntry(); 133} 134 135template<> 136inline Region* RegionNode::getNodeAs<Region>() const { 137 assert(isSubRegion() && "This is not a subregion RegionNode!"); 138 return reinterpret_cast<Region*>(const_cast<RegionNode*>(this)); 139} 140 141//===----------------------------------------------------------------------===// 142/// @brief A single entry single exit Region. 143/// 144/// A Region is a connected subgraph of a control flow graph that has exactly 145/// two connections to the remaining graph. It can be used to analyze or 146/// optimize parts of the control flow graph. 147/// 148/// A <em> simple Region </em> is connected to the remaing graph by just two 149/// edges. One edge entering the Region and another one leaving the Region. 150/// 151/// An <em> extended Region </em> (or just Region) is a subgraph that can be 152/// transform into a simple Region. The transformation is done by adding 153/// BasicBlocks that merge several entry or exit edges so that after the merge 154/// just one entry and one exit edge exists. 155/// 156/// The \e Entry of a Region is the first BasicBlock that is passed after 157/// entering the Region. It is an element of the Region. The entry BasicBlock 158/// dominates all BasicBlocks in the Region. 159/// 160/// The \e Exit of a Region is the first BasicBlock that is passed after 161/// leaving the Region. It is not an element of the Region. The exit BasicBlock, 162/// postdominates all BasicBlocks in the Region. 163/// 164/// A <em> canonical Region </em> cannot be constructed by combining smaller 165/// Regions. 166/// 167/// Region A is the \e parent of Region B, if B is completely contained in A. 168/// 169/// Two canonical Regions either do not intersect at all or one is 170/// the parent of the other. 171/// 172/// The <em> Program Structure Tree</em> is a graph (V, E) where V is the set of 173/// Regions in the control flow graph and E is the \e parent relation of these 174/// Regions. 175/// 176/// Example: 177/// 178/// \verbatim 179/// A simple control flow graph, that contains two regions. 180/// 181/// 1 182/// / | 183/// 2 | 184/// / \ 3 185/// 4 5 | 186/// | | | 187/// 6 7 8 188/// \ | / 189/// \ |/ Region A: 1 -> 9 {1,2,3,4,5,6,7,8} 190/// 9 Region B: 2 -> 9 {2,4,5,6,7} 191/// \endverbatim 192/// 193/// You can obtain more examples by either calling 194/// 195/// <tt> "opt -regions -analyze anyprogram.ll" </tt> 196/// or 197/// <tt> "opt -view-regions-only anyprogram.ll" </tt> 198/// 199/// on any LLVM file you are interested in. 200/// 201/// The first call returns a textual representation of the program structure 202/// tree, the second one creates a graphical representation using graphviz. 203class Region : public RegionNode { 204 friend class RegionInfo; 205 // DO NOT IMPLEMENT 206 Region(const Region &); 207 // DO NOT IMPLEMENT 208 const Region &operator=(const Region &); 209 210 // Information necessary to manage this Region. 211 RegionInfo* RI; 212 DominatorTree *DT; 213 214 // The exit BasicBlock of this region. 215 // (The entry BasicBlock is part of RegionNode) 216 BasicBlock *exit; 217 218 typedef std::vector<Region*> RegionSet; 219 220 // The subregions of this region. 221 RegionSet children; 222 223 typedef std::map<BasicBlock*, RegionNode*> BBNodeMapT; 224 225 // Save the BasicBlock RegionNodes that are element of this Region. 226 mutable BBNodeMapT BBNodeMap; 227 228 /// verifyBBInRegion - Check if a BB is in this Region. This check also works 229 /// if the region is incorrectly built. (EXPENSIVE!) 230 void verifyBBInRegion(BasicBlock* BB) const; 231 232 /// verifyWalk - Walk over all the BBs of the region starting from BB and 233 /// verify that all reachable basic blocks are elements of the region. 234 /// (EXPENSIVE!) 235 void verifyWalk(BasicBlock* BB, std::set<BasicBlock*>* visitedBB) const; 236 237 /// verifyRegionNest - Verify if the region and its children are valid 238 /// regions (EXPENSIVE!) 239 void verifyRegionNest() const; 240 241public: 242 /// @brief Create a new region. 243 /// 244 /// @param Entry The entry basic block of the region. 245 /// @param Exit The exit basic block of the region. 246 /// @param RI The region info object that is managing this region. 247 /// @param DT The dominator tree of the current function. 248 /// @param Parent The surrounding region or NULL if this is a top level 249 /// region. 250 Region(BasicBlock *Entry, BasicBlock *Exit, RegionInfo* RI, 251 DominatorTree *DT, Region *Parent = 0); 252 253 /// Delete the Region and all its subregions. 254 ~Region(); 255 256 /// @brief Get the entry BasicBlock of the Region. 257 /// @return The entry BasicBlock of the region. 258 BasicBlock *getEntry() const { return RegionNode::getEntry(); } 259 260 /// @brief Get the exit BasicBlock of the Region. 261 /// @return The exit BasicBlock of the Region, NULL if this is the TopLevel 262 /// Region. 263 BasicBlock *getExit() const { return exit; } 264 265 /// @brief Get the parent of the Region. 266 /// @return The parent of the Region or NULL if this is a top level 267 /// Region. 268 Region *getParent() const { return RegionNode::getParent(); } 269 270 /// @brief Get the RegionNode representing the current Region. 271 /// @return The RegionNode representing the current Region. 272 RegionNode* getNode() const { 273 return const_cast<RegionNode*>(reinterpret_cast<const RegionNode*>(this)); 274 } 275 276 /// @brief Get the nesting level of this Region. 277 /// 278 /// An toplevel Region has depth 0. 279 /// 280 /// @return The depth of the region. 281 unsigned getDepth() const; 282 283 /// @brief Is this a simple region? 284 /// 285 /// A region is simple if it has exactly one exit and one entry edge. 286 /// 287 /// @return True if the Region is simple. 288 bool isSimple() const; 289 290 /// @brief Returns the name of the Region. 291 /// @return The Name of the Region. 292 std::string getNameStr() const; 293 294 /// @brief Return the RegionInfo object, that belongs to this Region. 295 RegionInfo *getRegionInfo() const { 296 return RI; 297 } 298 299 /// @brief Print the region. 300 /// 301 /// @param OS The output stream the Region is printed to. 302 /// @param printTree Print also the tree of subregions. 303 /// @param level The indentation level used for printing. 304 void print(raw_ostream& OS, bool printTree = true, unsigned level = 0) const; 305 306 /// @brief Print the region to stderr. 307 void dump() const; 308 309 /// @brief Check if the region contains a BasicBlock. 310 /// 311 /// @param BB The BasicBlock that might be contained in this Region. 312 /// @return True if the block is contained in the region otherwise false. 313 bool contains(const BasicBlock *BB) const; 314 315 /// @brief Check if the region contains another region. 316 /// 317 /// @param SubRegion The region that might be contained in this Region. 318 /// @return True if SubRegion is contained in the region otherwise false. 319 bool contains(const Region *SubRegion) const { 320 // Toplevel Region. 321 if (!getExit()) 322 return true; 323 324 return contains(SubRegion->getEntry()) 325 && (contains(SubRegion->getExit()) || SubRegion->getExit() == getExit()); 326 } 327 328 /// @brief Check if the region contains an Instruction. 329 /// 330 /// @param Inst The Instruction that might be contained in this region. 331 /// @return True if the Instruction is contained in the region otherwise false. 332 bool contains(const Instruction *Inst) const { 333 return contains(Inst->getParent()); 334 } 335 336 /// @brief Check if the region contains a loop. 337 /// 338 /// @param L The loop that might be contained in this region. 339 /// @return True if the loop is contained in the region otherwise false. 340 /// In case a NULL pointer is passed to this function the result 341 /// is false, except for the region that describes the whole function. 342 /// In that case true is returned. 343 bool contains(const Loop *L) const; 344 345 /// @brief Get the outermost loop in the region that contains a loop. 346 /// 347 /// Find for a Loop L the outermost loop OuterL that is a parent loop of L 348 /// and is itself contained in the region. 349 /// 350 /// @param L The loop the lookup is started. 351 /// @return The outermost loop in the region, NULL if such a loop does not 352 /// exist or if the region describes the whole function. 353 Loop *outermostLoopInRegion(Loop *L) const; 354 355 /// @brief Get the outermost loop in the region that contains a basic block. 356 /// 357 /// Find for a basic block BB the outermost loop L that contains BB and is 358 /// itself contained in the region. 359 /// 360 /// @param LI A pointer to a LoopInfo analysis. 361 /// @param BB The basic block surrounded by the loop. 362 /// @return The outermost loop in the region, NULL if such a loop does not 363 /// exist or if the region describes the whole function. 364 Loop *outermostLoopInRegion(LoopInfo *LI, BasicBlock* BB) const; 365 366 /// @brief Get the subregion that starts at a BasicBlock 367 /// 368 /// @param BB The BasicBlock the subregion should start. 369 /// @return The Subregion if available, otherwise NULL. 370 Region* getSubRegionNode(BasicBlock *BB) const; 371 372 /// @brief Get the RegionNode for a BasicBlock 373 /// 374 /// @param BB The BasicBlock at which the RegionNode should start. 375 /// @return If available, the RegionNode that represents the subregion 376 /// starting at BB. If no subregion starts at BB, the RegionNode 377 /// representing BB. 378 RegionNode* getNode(BasicBlock *BB) const; 379 380 /// @brief Get the BasicBlock RegionNode for a BasicBlock 381 /// 382 /// @param BB The BasicBlock for which the RegionNode is requested. 383 /// @return The RegionNode representing the BB. 384 RegionNode* getBBNode(BasicBlock *BB) const; 385 386 /// @brief Add a new subregion to this Region. 387 /// 388 /// @param SubRegion The new subregion that will be added. 389 void addSubRegion(Region *SubRegion); 390 391 /// @brief Remove a subregion from this Region. 392 /// 393 /// The subregion is not deleted, as it will probably be inserted into another 394 /// region. 395 /// @param SubRegion The SubRegion that will be removed. 396 Region *removeSubRegion(Region *SubRegion); 397 398 /// @brief Move all direct child nodes of this Region to another Region. 399 /// 400 /// @param To The Region the child nodes will be transfered to. 401 void transferChildrenTo(Region *To); 402 403 /// @brief Verify if the region is a correct region. 404 /// 405 /// Check if this is a correctly build Region. This is an expensive check, as 406 /// the complete CFG of the Region will be walked. 407 void verifyRegion() const; 408 409 /// @brief Clear the cache for BB RegionNodes. 410 /// 411 /// After calling this function the BasicBlock RegionNodes will be stored at 412 /// different memory locations. RegionNodes obtained before this function is 413 /// called are therefore not comparable to RegionNodes abtained afterwords. 414 void clearNodeCache(); 415 416 /// @name Subregion Iterators 417 /// 418 /// These iterators iterator over all subregions of this Region. 419 //@{ 420 typedef RegionSet::iterator iterator; 421 typedef RegionSet::const_iterator const_iterator; 422 423 iterator begin() { return children.begin(); } 424 iterator end() { return children.end(); } 425 426 const_iterator begin() const { return children.begin(); } 427 const_iterator end() const { return children.end(); } 428 //@} 429 430 /// @name BasicBlock Iterators 431 /// 432 /// These iterators iterate over all BasicBlock RegionNodes that are 433 /// contained in this Region. The iterator also iterates over BasicBlocks 434 /// that are elements of a subregion of this Region. It is therefore called a 435 /// flat iterator. 436 //@{ 437 typedef df_iterator<RegionNode*, SmallPtrSet<RegionNode*, 8>, false, 438 GraphTraits<FlatIt<RegionNode*> > > block_iterator; 439 440 typedef df_iterator<const RegionNode*, SmallPtrSet<const RegionNode*, 8>, 441 false, GraphTraits<FlatIt<const RegionNode*> > > 442 const_block_iterator; 443 444 block_iterator block_begin(); 445 block_iterator block_end(); 446 447 const_block_iterator block_begin() const; 448 const_block_iterator block_end() const; 449 //@} 450 451 /// @name Element Iterators 452 /// 453 /// These iterators iterate over all BasicBlock and subregion RegionNodes that 454 /// are direct children of this Region. It does not iterate over any 455 /// RegionNodes that are also element of a subregion of this Region. 456 //@{ 457 typedef df_iterator<RegionNode*, SmallPtrSet<RegionNode*, 8>, false, 458 GraphTraits<RegionNode*> > element_iterator; 459 460 typedef df_iterator<const RegionNode*, SmallPtrSet<const RegionNode*, 8>, 461 false, GraphTraits<const RegionNode*> > 462 const_element_iterator; 463 464 element_iterator element_begin(); 465 element_iterator element_end(); 466 467 const_element_iterator element_begin() const; 468 const_element_iterator element_end() const; 469 //@} 470}; 471 472//===----------------------------------------------------------------------===// 473/// @brief Analysis that detects all canonical Regions. 474/// 475/// The RegionInfo pass detects all canonical regions in a function. The Regions 476/// are connected using the parent relation. This builds a Program Structure 477/// Tree. 478class RegionInfo : public FunctionPass { 479 typedef DenseMap<BasicBlock*,BasicBlock*> BBtoBBMap; 480 typedef DenseMap<BasicBlock*, Region*> BBtoRegionMap; 481 typedef SmallPtrSet<Region*, 4> RegionSet; 482 483 // DO NOT IMPLEMENT 484 RegionInfo(const RegionInfo &); 485 // DO NOT IMPLEMENT 486 const RegionInfo &operator=(const RegionInfo &); 487 488 DominatorTree *DT; 489 PostDominatorTree *PDT; 490 DominanceFrontier *DF; 491 492 /// The top level region. 493 Region *TopLevelRegion; 494 495 /// Map every BB to the smallest region, that contains BB. 496 BBtoRegionMap BBtoRegion; 497 498 // isCommonDomFrontier - Returns true if BB is in the dominance frontier of 499 // entry, because it was inherited from exit. In the other case there is an 500 // edge going from entry to BB without passing exit. 501 bool isCommonDomFrontier(BasicBlock* BB, BasicBlock* entry, 502 BasicBlock* exit) const; 503 504 // isRegion - Check if entry and exit surround a valid region, based on 505 // dominance tree and dominance frontier. 506 bool isRegion(BasicBlock* entry, BasicBlock* exit) const; 507 508 // insertShortCut - Saves a shortcut pointing from entry to exit. 509 // This function may extend this shortcut if possible. 510 void insertShortCut(BasicBlock* entry, BasicBlock* exit, 511 BBtoBBMap* ShortCut) const; 512 513 // getNextPostDom - Returns the next BB that postdominates N, while skipping 514 // all post dominators that cannot finish a canonical region. 515 DomTreeNode *getNextPostDom(DomTreeNode* N, BBtoBBMap *ShortCut) const; 516 517 // isTrivialRegion - A region is trivial, if it contains only one BB. 518 bool isTrivialRegion(BasicBlock *entry, BasicBlock *exit) const; 519 520 // createRegion - Creates a single entry single exit region. 521 Region *createRegion(BasicBlock *entry, BasicBlock *exit); 522 523 // findRegionsWithEntry - Detect all regions starting with bb 'entry'. 524 void findRegionsWithEntry(BasicBlock *entry, BBtoBBMap *ShortCut); 525 526 // scanForRegions - Detects regions in F. 527 void scanForRegions(Function &F, BBtoBBMap *ShortCut); 528 529 // getTopMostParent - Get the top most parent with the same entry block. 530 Region *getTopMostParent(Region *region); 531 532 // buildRegionsTree - build the region hierarchy after all region detected. 533 void buildRegionsTree(DomTreeNode *N, Region *region); 534 535 // Calculate - detecte all regions in function and build the region tree. 536 void Calculate(Function& F); 537 538 void releaseMemory(); 539 540 // updateStatistics - Update statistic about created regions. 541 void updateStatistics(Region *R); 542 543 // isSimple - Check if a region is a simple region with exactly one entry 544 // edge and exactly one exit edge. 545 bool isSimple(Region* R) const; 546 547public: 548 static char ID; 549 explicit RegionInfo(); 550 551 ~RegionInfo(); 552 553 /// @name FunctionPass interface 554 //@{ 555 virtual bool runOnFunction(Function &F); 556 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 557 virtual void print(raw_ostream &OS, const Module *) const; 558 virtual void verifyAnalysis() const; 559 //@} 560 561 /// @brief Get the smallest region that contains a BasicBlock. 562 /// 563 /// @param BB The basic block. 564 /// @return The smallest region, that contains BB or NULL, if there is no 565 /// region containing BB. 566 Region *getRegionFor(BasicBlock *BB) const; 567 568 /// @brief A shortcut for getRegionFor(). 569 /// 570 /// @param BB The basic block. 571 /// @return The smallest region, that contains BB or NULL, if there is no 572 /// region containing BB. 573 Region *operator[](BasicBlock *BB) const; 574 575 /// @brief Return the exit of the maximal refined region, that starts at a 576 /// BasicBlock. 577 /// 578 /// @param BB The BasicBlock the refined region starts. 579 BasicBlock *getMaxRegionExit(BasicBlock *BB) const; 580 581 /// @brief Find the smallest region that contains two regions. 582 /// 583 /// @param A The first region. 584 /// @param B The second region. 585 /// @return The smallest region containing A and B. 586 Region *getCommonRegion(Region* A, Region *B) const; 587 588 /// @brief Find the smallest region that contains two basic blocks. 589 /// 590 /// @param A The first basic block. 591 /// @param B The second basic block. 592 /// @return The smallest region that contains A and B. 593 Region* getCommonRegion(BasicBlock* A, BasicBlock *B) const { 594 return getCommonRegion(getRegionFor(A), getRegionFor(B)); 595 } 596 597 /// @brief Find the smallest region that contains a set of regions. 598 /// 599 /// @param Regions A vector of regions. 600 /// @return The smallest region that contains all regions in Regions. 601 Region* getCommonRegion(SmallVectorImpl<Region*> &Regions) const; 602 603 /// @brief Find the smallest region that contains a set of basic blocks. 604 /// 605 /// @param BBs A vector of basic blocks. 606 /// @return The smallest region that contains all basic blocks in BBS. 607 Region* getCommonRegion(SmallVectorImpl<BasicBlock*> &BBs) const; 608 609 Region *getTopLevelRegion() const { 610 return TopLevelRegion; 611 } 612 613 /// @brief Clear the Node Cache for all Regions. 614 /// 615 /// @see Region::clearNodeCache() 616 void clearNodeCache() { 617 if (TopLevelRegion) 618 TopLevelRegion->clearNodeCache(); 619 } 620}; 621 622inline raw_ostream &operator<<(raw_ostream &OS, const RegionNode &Node) { 623 if (Node.isSubRegion()) 624 return OS << Node.getNodeAs<Region>()->getNameStr(); 625 else 626 return OS << Node.getNodeAs<BasicBlock>()->getNameStr(); 627} 628} // End llvm namespace 629#endif 630 631