RegionInfo.h revision f96b0063674e6bf72da5429bd49097e33c2325c7
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; 40 41/// @brief Marker class to iterate over the elements of a Region in flat mode. 42/// 43/// The class is used to either iterate in Flat mode or by not using it to not 44/// iterate in Flat mode. During a Flat mode iteration all Regions are entered 45/// and the iteration returns every BasicBlock. If the Flat mode is not 46/// selected for SubRegions just one RegionNode containing the subregion is 47/// returned. 48template <class GraphType> 49class FlatIt {}; 50 51/// @brief A RegionNode represents a subregion or a BasicBlock that is part of a 52/// Region. 53class RegionNode { 54 // DO NOT IMPLEMENT 55 RegionNode(const RegionNode &); 56 // DO NOT IMPLEMENT 57 const RegionNode &operator=(const RegionNode &); 58 59 /// This is the entry basic block that starts this region node. If this is a 60 /// BasicBlock RegionNode, then entry is just the basic block, that this 61 /// RegionNode represents. Otherwise it is the entry of this (Sub)RegionNode. 62 /// 63 /// In the BBtoRegionNode map of the parent of this node, BB will always map 64 /// to this node no matter which kind of node this one is. 65 /// 66 /// The node can hold either a Region or a BasicBlock. 67 /// Use one bit to save, if this RegionNode is a subregion or BasicBlock 68 /// RegionNode. 69 PointerIntPair<BasicBlock*, 1, bool> entry; 70 71protected: 72 /// @brief The parent Region of this RegionNode. 73 /// @see getParent() 74 Region* parent; 75 76public: 77 /// @brief Create a RegionNode. 78 /// 79 /// @param Parent The parent of this RegionNode. 80 /// @param Entry The entry BasicBlock of the RegionNode. If this 81 /// RegionNode represents a BasicBlock, this is the 82 /// BasicBlock itself. If it represents a subregion, this 83 /// is the entry BasicBlock of the subregion. 84 /// @param isSubRegion If this RegionNode represents a SubRegion. 85 inline RegionNode(Region* Parent, BasicBlock* Entry, bool isSubRegion = 0) 86 : entry(Entry, isSubRegion), parent(Parent) {} 87 88 /// @brief Get the parent Region of this RegionNode. 89 /// 90 /// The parent Region is the Region this RegionNode belongs to. If for 91 /// example a BasicBlock is element of two Regions, there exist two 92 /// RegionNodes for this BasicBlock. Each with the getParent() function 93 /// pointing to the Region this RegionNode belongs to. 94 /// 95 /// @return Get the parent Region of this RegionNode. 96 inline Region* getParent() const { return parent; } 97 98 /// @brief Get the entry BasicBlock of this RegionNode. 99 /// 100 /// If this RegionNode represents a BasicBlock this is just the BasicBlock 101 /// itself, otherwise we return the entry BasicBlock of the Subregion 102 /// 103 /// @return The entry BasicBlock of this RegionNode. 104 inline BasicBlock* getEntry() const { return entry.getPointer(); } 105 106 /// @brief Get the content of this RegionNode. 107 /// 108 /// This can be either a BasicBlock or a subregion. Before calling getNodeAs() 109 /// check the type of the content with the isSubRegion() function call. 110 /// 111 /// @return The content of this RegionNode. 112 template<class T> 113 inline T* getNodeAs() const; 114 115 /// @brief Is this RegionNode a subregion? 116 /// 117 /// @return True if it contains a subregion. False if it contains a 118 /// BasicBlock. 119 inline bool isSubRegion() const { 120 return entry.getInt(); 121 } 122}; 123 124/// Print a RegionNode. 125inline raw_ostream &operator<<(raw_ostream &OS, const RegionNode &Node); 126 127template<> 128inline BasicBlock* RegionNode::getNodeAs<BasicBlock>() const { 129 assert(!isSubRegion() && "This is not a BasicBlock RegionNode!"); 130 return getEntry(); 131} 132 133template<> 134inline Region* RegionNode::getNodeAs<Region>() const { 135 assert(isSubRegion() && "This is not a subregion RegionNode!"); 136 return reinterpret_cast<Region*>(const_cast<RegionNode*>(this)); 137} 138 139//===----------------------------------------------------------------------===// 140/// @brief A single entry single exit Region. 141/// 142/// A Region is a connected subgraph of a control flow graph that has exactly 143/// two connections to the remaining graph. It can be used to analyze or 144/// optimize parts of the control flow graph. 145/// 146/// A <em> simple Region </em> is connected to the remaing graph by just two 147/// edges. One edge entering the Region and another one leaving the Region. 148/// 149/// An <em> extended Region </em> (or just Region) is a subgraph that can be 150/// transform into a simple Region. The transformation is done by adding 151/// BasicBlocks that merge several entry or exit edges so that after the merge 152/// just one entry and one exit edge exists. 153/// 154/// The \e Entry of a Region is the first BasicBlock that is passed after 155/// entering the Region. It is an element of the Region. The entry BasicBlock 156/// dominates all BasicBlocks in the Region. 157/// 158/// The \e Exit of a Region is the first BasicBlock that is passed after 159/// leaving the Region. It is not an element of the Region. The exit BasicBlock, 160/// postdominates all BasicBlocks in the Region. 161/// 162/// A <em> canonical Region </em> cannot be constructed by combining smaller 163/// Regions. 164/// 165/// Region A is the \e parent of Region B, if B is completely contained in A. 166/// 167/// Two canonical Regions either do not intersect at all or one is 168/// the parent of the other. 169/// 170/// The <em> Program Structure Tree</em> is a graph (V, E) where V is the set of 171/// Regions in the control flow graph and E is the \e parent relation of these 172/// Regions. 173/// 174/// Example: 175/// 176/// \verbatim 177/// A simple control flow graph, that contains two regions. 178/// 179/// 1 180/// / | 181/// 2 | 182/// / \ 3 183/// 4 5 | 184/// | | | 185/// 6 7 8 186/// \ | / 187/// \ |/ Region A: 1 -> 9 {1,2,3,4,5,6,7,8} 188/// 9 Region B: 2 -> 9 {2,4,5,6,7} 189/// \endverbatim 190/// 191/// You can obtain more examples by either calling 192/// 193/// <tt> "opt -regions -analyze anyprogram.ll" </tt> 194/// or 195/// <tt> "opt -view-regions-only anyprogram.ll" </tt> 196/// 197/// on any LLVM file you are interested in. 198/// 199/// The first call returns a textual representation of the program structure 200/// tree, the second one creates a graphical representation using graphviz. 201class Region : public RegionNode { 202 friend class RegionInfo; 203 // DO NOT IMPLEMENT 204 Region(const Region &); 205 // DO NOT IMPLEMENT 206 const Region &operator=(const Region &); 207 208 // Information necessary to manage this Region. 209 RegionInfo* RI; 210 DominatorTree *DT; 211 212 // The exit BasicBlock of this region. 213 // (The entry BasicBlock is part of RegionNode) 214 BasicBlock *exit; 215 216 typedef std::vector<Region*> RegionSet; 217 218 // The subregions of this region. 219 RegionSet children; 220 221 typedef std::map<BasicBlock*, RegionNode*> BBNodeMapT; 222 223 // Save the BasicBlock RegionNodes that are element of this Region. 224 mutable BBNodeMapT BBNodeMap; 225 226 /// verifyBBInRegion - Check if a BB is in this Region. This check also works 227 /// if the region is incorrectly built. (EXPENSIVE!) 228 void verifyBBInRegion(BasicBlock* BB) const; 229 230 /// verifyWalk - Walk over all the BBs of the region starting from BB and 231 /// verify that all reachable basic blocks are elements of the region. 232 /// (EXPENSIVE!) 233 void verifyWalk(BasicBlock* BB, std::set<BasicBlock*>* visitedBB) const; 234 235 /// verifyRegionNest - Verify if the region and its children are valid 236 /// regions (EXPENSIVE!) 237 void verifyRegionNest() const; 238 239public: 240 /// @brief Create a new region. 241 /// 242 /// @param Entry The entry basic block of the region. 243 /// @param Exit The exit basic block of the region. 244 /// @param RI The region info object that is managing this region. 245 /// @param DT The dominator tree of the current function. 246 /// @param Parent The surrounding region or NULL if this is a top level 247 /// region. 248 Region(BasicBlock *Entry, BasicBlock *Exit, RegionInfo* RI, 249 DominatorTree *DT, Region *Parent = 0); 250 251 /// Delete the Region and all its subregions. 252 ~Region(); 253 254 /// @brief Get the entry BasicBlock of the Region. 255 /// @return The entry BasicBlock of the region. 256 BasicBlock *getEntry() const { return RegionNode::getEntry(); } 257 258 /// @brief Get the exit BasicBlock of the Region. 259 /// @return The exit BasicBlock of the Region, NULL if this is the TopLevel 260 /// Region. 261 BasicBlock *getExit() const { return exit; } 262 263 /// @brief Get the parent of the Region. 264 /// @return The parent of the Region or NULL if this is a top level 265 /// Region. 266 Region *getParent() const { return RegionNode::getParent(); } 267 268 /// @brief Get the RegionNode representing the current Region. 269 /// @return The RegionNode representing the current Region. 270 RegionNode* getNode() const { 271 return const_cast<RegionNode*>(reinterpret_cast<const RegionNode*>(this)); 272 } 273 274 /// @brief Get the nesting level of this Region. 275 /// 276 /// An toplevel Region has depth 0. 277 /// 278 /// @return The depth of the region. 279 unsigned getDepth() const; 280 281 /// @brief Is this a simple region? 282 /// 283 /// A region is simple if it has exactly one exit and one entry edge. 284 /// 285 /// @return True if the Region is simple. 286 bool isSimple() const; 287 288 /// @brief Returns the name of the Region. 289 /// @return The Name of the Region. 290 std::string getNameStr() const { 291 std::string exitName; 292 293 if (getExit()) 294 exitName = getExit()->getNameStr(); 295 else 296 exitName = "<Function Return>"; 297 298 return getEntry()->getNameStr() + " => " + exitName; 299 } 300 301 /// @brief Return the RegionInfo object, that belongs to this Region. 302 RegionInfo *getRegionInfo() const { 303 return RI; 304 } 305 306 /// @brief Print the region. 307 /// 308 /// @param OS The output stream the Region is printed to. 309 /// @param printTree Print also the tree of subregions. 310 /// @param level The indentation level used for printing. 311 void print(raw_ostream& OS, bool printTree = true, unsigned level = 0) const; 312 313 /// @brief Print the region to stderr. 314 void dump() const; 315 316 /// @brief Check if the region contains a BasicBlock. 317 /// 318 /// @param BB The BasicBlock that might be contained in this Region. 319 /// @return True if the block is contained in the region otherwise false. 320 bool contains(const BasicBlock *BB) const; 321 322 /// @brief Check if the region contains another region. 323 /// 324 /// @param SubRegion The region that might be contained in this Region. 325 /// @return True if SubRegion is contained in the region otherwise false. 326 bool contains(const Region *SubRegion) const { 327 // Toplevel Region. 328 if (!getExit()) 329 return true; 330 331 return contains(SubRegion->getEntry()) 332 && (contains(SubRegion->getExit()) || SubRegion->getExit() == getExit()); 333 } 334 335 /// @brief Check if the region contains an Instruction. 336 /// 337 /// @param Inst The Instruction that might be contained in this region. 338 /// @return True if the Instruction is contained in the region otherwise false. 339 bool contains(const Instruction *Inst) const { 340 return contains(Inst->getParent()); 341 } 342 343 /// @brief Get the subregion that starts at a BasicBlock 344 /// 345 /// @param BB The BasicBlock the subregion should start. 346 /// @return The Subregion if available, otherwise NULL. 347 Region* getSubRegionNode(BasicBlock *BB) const; 348 349 /// @brief Get the RegionNode for a BasicBlock 350 /// 351 /// @param BB The BasicBlock at which the RegionNode should start. 352 /// @return If available, the RegionNode that represents the subregion 353 /// starting at BB. If no subregion starts at BB, the RegionNode 354 /// representing BB. 355 RegionNode* getNode(BasicBlock *BB) const; 356 357 /// @brief Get the BasicBlock RegionNode for a BasicBlock 358 /// 359 /// @param BB The BasicBlock for which the RegionNode is requested. 360 /// @return The RegionNode representing the BB. 361 RegionNode* getBBNode(BasicBlock *BB) const; 362 363 /// @brief Add a new subregion to this Region. 364 /// 365 /// @param SubRegion The new subregion that will be added. 366 void addSubRegion(Region *SubRegion); 367 368 /// @brief Remove a subregion from this Region. 369 /// 370 /// The subregion is not deleted, as it will probably be inserted into another 371 /// region. 372 /// @param SubRegion The SubRegion that will be removed. 373 Region *removeSubRegion(Region *SubRegion); 374 375 /// @brief Move all direct child nodes of this Region to another Region. 376 /// 377 /// @param To The Region the child nodes will be transfered to. 378 void transferChildrenTo(Region *To); 379 380 /// @brief Verify if the region is a correct region. 381 /// 382 /// Check if this is a correctly build Region. This is an expensive check, as 383 /// the complete CFG of the Region will be walked. 384 void verifyRegion() const; 385 386 /// @brief Clear the cache for BB RegionNodes. 387 /// 388 /// After calling this function the BasicBlock RegionNodes will be stored at 389 /// different memory locations. RegionNodes obtained before this function is 390 /// called are therefore not comparable to RegionNodes abtained afterwords. 391 void clearNodeCache(); 392 393 /// @name Subregion Iterators 394 /// 395 /// These iterators iterator over all subregions of this Region. 396 //@{ 397 typedef RegionSet::iterator iterator; 398 typedef RegionSet::const_iterator const_iterator; 399 400 iterator begin() { return children.begin(); } 401 iterator end() { return children.end(); } 402 403 const_iterator begin() const { return children.begin(); } 404 const_iterator end() const { return children.end(); } 405 //@} 406 407 /// @name BasicBlock Iterators 408 /// 409 /// These iterators iterate over all BasicBlock RegionNodes that are 410 /// contained in this Region. The iterator also iterates over BasicBlocks 411 /// that are elements of a subregion of this Region. It is therefore called a 412 /// flat iterator. 413 //@{ 414 typedef df_iterator<RegionNode*, SmallPtrSet<RegionNode*, 8>, false, 415 GraphTraits<FlatIt<RegionNode*> > > block_iterator; 416 417 typedef df_iterator<const RegionNode*, SmallPtrSet<const RegionNode*, 8>, 418 false, GraphTraits<FlatIt<const RegionNode*> > > 419 const_block_iterator; 420 421 block_iterator block_begin(); 422 block_iterator block_end(); 423 424 const_block_iterator block_begin() const; 425 const_block_iterator block_end() const; 426 //@} 427 428 /// @name Element Iterators 429 /// 430 /// These iterators iterate over all BasicBlock and subregion RegionNodes that 431 /// are direct children of this Region. It does not iterate over any 432 /// RegionNodes that are also element of a subregion of this Region. 433 //@{ 434 typedef df_iterator<RegionNode*, SmallPtrSet<RegionNode*, 8>, false, 435 GraphTraits<RegionNode*> > element_iterator; 436 437 typedef df_iterator<const RegionNode*, SmallPtrSet<const RegionNode*, 8>, 438 false, GraphTraits<const RegionNode*> > 439 const_element_iterator; 440 441 element_iterator element_begin(); 442 element_iterator element_end(); 443 444 const_element_iterator element_begin() const; 445 const_element_iterator element_end() const; 446 //@} 447}; 448 449//===----------------------------------------------------------------------===// 450/// @brief Analysis that detects all canonical Regions. 451/// 452/// The RegionInfo pass detects all canonical regions in a function. The Regions 453/// are connected using the parent relation. This builds a Program Structure 454/// Tree. 455class RegionInfo : public FunctionPass { 456 typedef DenseMap<BasicBlock*,BasicBlock*> BBtoBBMap; 457 typedef DenseMap<BasicBlock*, Region*> BBtoRegionMap; 458 typedef SmallPtrSet<Region*, 4> RegionSet; 459 460 // DO NOT IMPLEMENT 461 RegionInfo(const RegionInfo &); 462 // DO NOT IMPLEMENT 463 const RegionInfo &operator=(const RegionInfo &); 464 465 DominatorTree *DT; 466 PostDominatorTree *PDT; 467 DominanceFrontier *DF; 468 469 /// The top level region. 470 Region *TopLevelRegion; 471 472 /// Map every BB to the smallest region, that contains BB. 473 BBtoRegionMap BBtoRegion; 474 475 // isCommonDomFrontier - Returns true if BB is in the dominance frontier of 476 // entry, because it was inherited from exit. In the other case there is an 477 // edge going from entry to BB without passing exit. 478 bool isCommonDomFrontier(BasicBlock* BB, BasicBlock* entry, 479 BasicBlock* exit) const; 480 481 // isRegion - Check if entry and exit surround a valid region, based on 482 // dominance tree and dominance frontier. 483 bool isRegion(BasicBlock* entry, BasicBlock* exit) const; 484 485 // insertShortCut - Saves a shortcut pointing from entry to exit. 486 // This function may extend this shortcut if possible. 487 void insertShortCut(BasicBlock* entry, BasicBlock* exit, 488 BBtoBBMap* ShortCut) const; 489 490 // getNextPostDom - Returns the next BB that postdominates N, while skipping 491 // all post dominators that cannot finish a canonical region. 492 DomTreeNode *getNextPostDom(DomTreeNode* N, BBtoBBMap *ShortCut) const; 493 494 // isTrivialRegion - A region is trivial, if it contains only one BB. 495 bool isTrivialRegion(BasicBlock *entry, BasicBlock *exit) const; 496 497 // createRegion - Creates a single entry single exit region. 498 Region *createRegion(BasicBlock *entry, BasicBlock *exit); 499 500 // findRegionsWithEntry - Detect all regions starting with bb 'entry'. 501 void findRegionsWithEntry(BasicBlock *entry, BBtoBBMap *ShortCut); 502 503 // scanForRegions - Detects regions in F. 504 void scanForRegions(Function &F, BBtoBBMap *ShortCut); 505 506 // getTopMostParent - Get the top most parent with the same entry block. 507 Region *getTopMostParent(Region *region); 508 509 // buildRegionsTree - build the region hierarchy after all region detected. 510 void buildRegionsTree(DomTreeNode *N, Region *region); 511 512 // Calculate - detecte all regions in function and build the region tree. 513 void Calculate(Function& F); 514 515 void releaseMemory(); 516 517 // updateStatistics - Update statistic about created regions. 518 void updateStatistics(Region *R); 519 520 // isSimple - Check if a region is a simple region with exactly one entry 521 // edge and exactly one exit edge. 522 bool isSimple(Region* R) const; 523 524public: 525 static char ID; 526 explicit RegionInfo(); 527 528 ~RegionInfo(); 529 530 /// @name FunctionPass interface 531 //@{ 532 virtual bool runOnFunction(Function &F); 533 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 534 virtual void print(raw_ostream &OS, const Module *) const; 535 virtual void verifyAnalysis() const; 536 //@} 537 538 /// @brief Get the smallest region that contains a BasicBlock. 539 /// 540 /// @param BB The basic block. 541 /// @return The smallest region, that contains BB or NULL, if there is no 542 /// region containing BB. 543 Region *getRegionFor(BasicBlock *BB) const; 544 545 /// @brief A shortcut for getRegionFor(). 546 /// 547 /// @param BB The basic block. 548 /// @return The smallest region, that contains BB or NULL, if there is no 549 /// region containing BB. 550 Region *operator[](BasicBlock *BB) const; 551 552 /// @brief Find the smallest region that contains two regions. 553 /// 554 /// @param A The first region. 555 /// @param B The second region. 556 /// @return The smallest region containing A and B. 557 Region *getCommonRegion(Region* A, Region *B) const; 558 559 /// @brief Find the smallest region that contains two basic blocks. 560 /// 561 /// @param A The first basic block. 562 /// @param B The second basic block. 563 /// @return The smallest region that contains A and B. 564 Region* getCommonRegion(BasicBlock* A, BasicBlock *B) const { 565 return getCommonRegion(getRegionFor(A), getRegionFor(B)); 566 } 567 568 /// @brief Find the smallest region that contains a set of regions. 569 /// 570 /// @param Regions A vector of regions. 571 /// @return The smallest region that contains all regions in Regions. 572 Region* getCommonRegion(SmallVectorImpl<Region*> &Regions) const; 573 574 /// @brief Find the smallest region that contains a set of basic blocks. 575 /// 576 /// @param BBs A vector of basic blocks. 577 /// @return The smallest region that contains all basic blocks in BBS. 578 Region* getCommonRegion(SmallVectorImpl<BasicBlock*> &BBs) const; 579 580 Region *getTopLevelRegion() const { 581 return TopLevelRegion; 582 } 583 584 /// @brief Clear the Node Cache for all Regions. 585 /// 586 /// @see Region::clearNodeCache() 587 void clearNodeCache() { 588 if (TopLevelRegion) 589 TopLevelRegion->clearNodeCache(); 590 } 591}; 592 593inline raw_ostream &operator<<(raw_ostream &OS, const RegionNode &Node) { 594 if (Node.isSubRegion()) 595 return OS << Node.getNodeAs<Region>()->getNameStr(); 596 else 597 return OS << Node.getNodeAs<BasicBlock>()->getNameStr(); 598} 599} // End llvm namespace 600#endif 601 602