1 //===- llvm/Analysis/LoopInfoImpl.h - Natural Loop Calculator ---*- 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 // This is the generic implementation of LoopInfo used for both Loops and 11 // MachineLoops. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_ANALYSIS_LOOPINFOIMPL_H 16 #define LLVM_ANALYSIS_LOOPINFOIMPL_H 17 18 #include "llvm/ADT/DepthFirstIterator.h" 19 #include "llvm/ADT/PostOrderIterator.h" 20 #include "llvm/ADT/STLExtras.h" 21 #include "llvm/ADT/SetVector.h" 22 #include "llvm/Analysis/LoopInfo.h" 23 #include "llvm/IR/Dominators.h" 24 25 namespace llvm { 26 27 //===----------------------------------------------------------------------===// 28 // APIs for simple analysis of the loop. See header notes. 29 30 /// getExitingBlocks - Return all blocks inside the loop that have successors 31 /// outside of the loop. These are the blocks _inside of the current loop_ 32 /// which branch out. The returned list is always unique. 33 /// 34 template <class BlockT, class LoopT> 35 void LoopBase<BlockT, LoopT>::getExitingBlocks( 36 SmallVectorImpl<BlockT *> &ExitingBlocks) const { 37 assert(!isInvalid() && "Loop not in a valid state!"); 38 for (const auto BB : blocks()) 39 for (const auto &Succ : children<BlockT *>(BB)) 40 if (!contains(Succ)) { 41 // Not in current loop? It must be an exit block. 42 ExitingBlocks.push_back(BB); 43 break; 44 } 45 } 46 47 /// getExitingBlock - If getExitingBlocks would return exactly one block, 48 /// return that block. Otherwise return null. 49 template <class BlockT, class LoopT> 50 BlockT *LoopBase<BlockT, LoopT>::getExitingBlock() const { 51 assert(!isInvalid() && "Loop not in a valid state!"); 52 SmallVector<BlockT *, 8> ExitingBlocks; 53 getExitingBlocks(ExitingBlocks); 54 if (ExitingBlocks.size() == 1) 55 return ExitingBlocks[0]; 56 return nullptr; 57 } 58 59 /// getExitBlocks - Return all of the successor blocks of this loop. These 60 /// are the blocks _outside of the current loop_ which are branched to. 61 /// 62 template <class BlockT, class LoopT> 63 void LoopBase<BlockT, LoopT>::getExitBlocks( 64 SmallVectorImpl<BlockT *> &ExitBlocks) const { 65 assert(!isInvalid() && "Loop not in a valid state!"); 66 for (const auto BB : blocks()) 67 for (const auto &Succ : children<BlockT *>(BB)) 68 if (!contains(Succ)) 69 // Not in current loop? It must be an exit block. 70 ExitBlocks.push_back(Succ); 71 } 72 73 /// getExitBlock - If getExitBlocks would return exactly one block, 74 /// return that block. Otherwise return null. 75 template <class BlockT, class LoopT> 76 BlockT *LoopBase<BlockT, LoopT>::getExitBlock() const { 77 assert(!isInvalid() && "Loop not in a valid state!"); 78 SmallVector<BlockT *, 8> ExitBlocks; 79 getExitBlocks(ExitBlocks); 80 if (ExitBlocks.size() == 1) 81 return ExitBlocks[0]; 82 return nullptr; 83 } 84 85 template <class BlockT, class LoopT> 86 bool LoopBase<BlockT, LoopT>::hasDedicatedExits() const { 87 // Each predecessor of each exit block of a normal loop is contained 88 // within the loop. 89 SmallVector<BlockT *, 4> ExitBlocks; 90 getExitBlocks(ExitBlocks); 91 for (BlockT *EB : ExitBlocks) 92 for (BlockT *Predecessor : children<Inverse<BlockT *>>(EB)) 93 if (!contains(Predecessor)) 94 return false; 95 // All the requirements are met. 96 return true; 97 } 98 99 template <class BlockT, class LoopT> 100 void LoopBase<BlockT, LoopT>::getUniqueExitBlocks( 101 SmallVectorImpl<BlockT *> &ExitBlocks) const { 102 typedef GraphTraits<BlockT *> BlockTraits; 103 typedef GraphTraits<Inverse<BlockT *>> InvBlockTraits; 104 105 assert(hasDedicatedExits() && 106 "getUniqueExitBlocks assumes the loop has canonical form exits!"); 107 108 SmallVector<BlockT *, 32> SwitchExitBlocks; 109 for (BlockT *Block : this->blocks()) { 110 SwitchExitBlocks.clear(); 111 for (BlockT *Successor : children<BlockT *>(Block)) { 112 // If block is inside the loop then it is not an exit block. 113 if (contains(Successor)) 114 continue; 115 116 BlockT *FirstPred = *InvBlockTraits::child_begin(Successor); 117 118 // If current basic block is this exit block's first predecessor then only 119 // insert exit block in to the output ExitBlocks vector. This ensures that 120 // same exit block is not inserted twice into ExitBlocks vector. 121 if (Block != FirstPred) 122 continue; 123 124 // If a terminator has more then two successors, for example SwitchInst, 125 // then it is possible that there are multiple edges from current block to 126 // one exit block. 127 if (std::distance(BlockTraits::child_begin(Block), 128 BlockTraits::child_end(Block)) <= 2) { 129 ExitBlocks.push_back(Successor); 130 continue; 131 } 132 133 // In case of multiple edges from current block to exit block, collect 134 // only one edge in ExitBlocks. Use switchExitBlocks to keep track of 135 // duplicate edges. 136 if (!is_contained(SwitchExitBlocks, Successor)) { 137 SwitchExitBlocks.push_back(Successor); 138 ExitBlocks.push_back(Successor); 139 } 140 } 141 } 142 } 143 144 template <class BlockT, class LoopT> 145 BlockT *LoopBase<BlockT, LoopT>::getUniqueExitBlock() const { 146 SmallVector<BlockT *, 8> UniqueExitBlocks; 147 getUniqueExitBlocks(UniqueExitBlocks); 148 if (UniqueExitBlocks.size() == 1) 149 return UniqueExitBlocks[0]; 150 return nullptr; 151 } 152 153 /// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). 154 template <class BlockT, class LoopT> 155 void LoopBase<BlockT, LoopT>::getExitEdges( 156 SmallVectorImpl<Edge> &ExitEdges) const { 157 assert(!isInvalid() && "Loop not in a valid state!"); 158 for (const auto BB : blocks()) 159 for (const auto &Succ : children<BlockT *>(BB)) 160 if (!contains(Succ)) 161 // Not in current loop? It must be an exit block. 162 ExitEdges.emplace_back(BB, Succ); 163 } 164 165 /// getLoopPreheader - If there is a preheader for this loop, return it. A 166 /// loop has a preheader if there is only one edge to the header of the loop 167 /// from outside of the loop and it is legal to hoist instructions into the 168 /// predecessor. If this is the case, the block branching to the header of the 169 /// loop is the preheader node. 170 /// 171 /// This method returns null if there is no preheader for the loop. 172 /// 173 template <class BlockT, class LoopT> 174 BlockT *LoopBase<BlockT, LoopT>::getLoopPreheader() const { 175 assert(!isInvalid() && "Loop not in a valid state!"); 176 // Keep track of nodes outside the loop branching to the header... 177 BlockT *Out = getLoopPredecessor(); 178 if (!Out) 179 return nullptr; 180 181 // Make sure we are allowed to hoist instructions into the predecessor. 182 if (!Out->isLegalToHoistInto()) 183 return nullptr; 184 185 // Make sure there is only one exit out of the preheader. 186 typedef GraphTraits<BlockT *> BlockTraits; 187 typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out); 188 ++SI; 189 if (SI != BlockTraits::child_end(Out)) 190 return nullptr; // Multiple exits from the block, must not be a preheader. 191 192 // The predecessor has exactly one successor, so it is a preheader. 193 return Out; 194 } 195 196 /// getLoopPredecessor - If the given loop's header has exactly one unique 197 /// predecessor outside the loop, return it. Otherwise return null. 198 /// This is less strict that the loop "preheader" concept, which requires 199 /// the predecessor to have exactly one successor. 200 /// 201 template <class BlockT, class LoopT> 202 BlockT *LoopBase<BlockT, LoopT>::getLoopPredecessor() const { 203 assert(!isInvalid() && "Loop not in a valid state!"); 204 // Keep track of nodes outside the loop branching to the header... 205 BlockT *Out = nullptr; 206 207 // Loop over the predecessors of the header node... 208 BlockT *Header = getHeader(); 209 for (const auto Pred : children<Inverse<BlockT *>>(Header)) { 210 if (!contains(Pred)) { // If the block is not in the loop... 211 if (Out && Out != Pred) 212 return nullptr; // Multiple predecessors outside the loop 213 Out = Pred; 214 } 215 } 216 217 // Make sure there is only one exit out of the preheader. 218 assert(Out && "Header of loop has no predecessors from outside loop?"); 219 return Out; 220 } 221 222 /// getLoopLatch - If there is a single latch block for this loop, return it. 223 /// A latch block is a block that contains a branch back to the header. 224 template <class BlockT, class LoopT> 225 BlockT *LoopBase<BlockT, LoopT>::getLoopLatch() const { 226 assert(!isInvalid() && "Loop not in a valid state!"); 227 BlockT *Header = getHeader(); 228 BlockT *Latch = nullptr; 229 for (const auto Pred : children<Inverse<BlockT *>>(Header)) { 230 if (contains(Pred)) { 231 if (Latch) 232 return nullptr; 233 Latch = Pred; 234 } 235 } 236 237 return Latch; 238 } 239 240 //===----------------------------------------------------------------------===// 241 // APIs for updating loop information after changing the CFG 242 // 243 244 /// addBasicBlockToLoop - This method is used by other analyses to update loop 245 /// information. NewBB is set to be a new member of the current loop. 246 /// Because of this, it is added as a member of all parent loops, and is added 247 /// to the specified LoopInfo object as being in the current basic block. It 248 /// is not valid to replace the loop header with this method. 249 /// 250 template <class BlockT, class LoopT> 251 void LoopBase<BlockT, LoopT>::addBasicBlockToLoop( 252 BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LIB) { 253 assert(!isInvalid() && "Loop not in a valid state!"); 254 #ifndef NDEBUG 255 if (!Blocks.empty()) { 256 auto SameHeader = LIB[getHeader()]; 257 assert(contains(SameHeader) && getHeader() == SameHeader->getHeader() && 258 "Incorrect LI specified for this loop!"); 259 } 260 #endif 261 assert(NewBB && "Cannot add a null basic block to the loop!"); 262 assert(!LIB[NewBB] && "BasicBlock already in the loop!"); 263 264 LoopT *L = static_cast<LoopT *>(this); 265 266 // Add the loop mapping to the LoopInfo object... 267 LIB.BBMap[NewBB] = L; 268 269 // Add the basic block to this loop and all parent loops... 270 while (L) { 271 L->addBlockEntry(NewBB); 272 L = L->getParentLoop(); 273 } 274 } 275 276 /// replaceChildLoopWith - This is used when splitting loops up. It replaces 277 /// the OldChild entry in our children list with NewChild, and updates the 278 /// parent pointer of OldChild to be null and the NewChild to be this loop. 279 /// This updates the loop depth of the new child. 280 template <class BlockT, class LoopT> 281 void LoopBase<BlockT, LoopT>::replaceChildLoopWith(LoopT *OldChild, 282 LoopT *NewChild) { 283 assert(!isInvalid() && "Loop not in a valid state!"); 284 assert(OldChild->ParentLoop == this && "This loop is already broken!"); 285 assert(!NewChild->ParentLoop && "NewChild already has a parent!"); 286 typename std::vector<LoopT *>::iterator I = find(SubLoops, OldChild); 287 assert(I != SubLoops.end() && "OldChild not in loop!"); 288 *I = NewChild; 289 OldChild->ParentLoop = nullptr; 290 NewChild->ParentLoop = static_cast<LoopT *>(this); 291 } 292 293 /// verifyLoop - Verify loop structure 294 template <class BlockT, class LoopT> 295 void LoopBase<BlockT, LoopT>::verifyLoop() const { 296 assert(!isInvalid() && "Loop not in a valid state!"); 297 #ifndef NDEBUG 298 assert(!Blocks.empty() && "Loop header is missing"); 299 300 // Setup for using a depth-first iterator to visit every block in the loop. 301 SmallVector<BlockT *, 8> ExitBBs; 302 getExitBlocks(ExitBBs); 303 df_iterator_default_set<BlockT *> VisitSet; 304 VisitSet.insert(ExitBBs.begin(), ExitBBs.end()); 305 df_ext_iterator<BlockT *, df_iterator_default_set<BlockT *>> 306 BI = df_ext_begin(getHeader(), VisitSet), 307 BE = df_ext_end(getHeader(), VisitSet); 308 309 // Keep track of the BBs visited. 310 SmallPtrSet<BlockT *, 8> VisitedBBs; 311 312 // Check the individual blocks. 313 for (; BI != BE; ++BI) { 314 BlockT *BB = *BI; 315 316 assert(std::any_of(GraphTraits<BlockT *>::child_begin(BB), 317 GraphTraits<BlockT *>::child_end(BB), 318 [&](BlockT *B) { return contains(B); }) && 319 "Loop block has no in-loop successors!"); 320 321 assert(std::any_of(GraphTraits<Inverse<BlockT *>>::child_begin(BB), 322 GraphTraits<Inverse<BlockT *>>::child_end(BB), 323 [&](BlockT *B) { return contains(B); }) && 324 "Loop block has no in-loop predecessors!"); 325 326 SmallVector<BlockT *, 2> OutsideLoopPreds; 327 std::for_each(GraphTraits<Inverse<BlockT *>>::child_begin(BB), 328 GraphTraits<Inverse<BlockT *>>::child_end(BB), 329 [&](BlockT *B) { 330 if (!contains(B)) 331 OutsideLoopPreds.push_back(B); 332 }); 333 334 if (BB == getHeader()) { 335 assert(!OutsideLoopPreds.empty() && "Loop is unreachable!"); 336 } else if (!OutsideLoopPreds.empty()) { 337 // A non-header loop shouldn't be reachable from outside the loop, 338 // though it is permitted if the predecessor is not itself actually 339 // reachable. 340 BlockT *EntryBB = &BB->getParent()->front(); 341 for (BlockT *CB : depth_first(EntryBB)) 342 for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i) 343 assert(CB != OutsideLoopPreds[i] && 344 "Loop has multiple entry points!"); 345 } 346 assert(BB != &getHeader()->getParent()->front() && 347 "Loop contains function entry block!"); 348 349 VisitedBBs.insert(BB); 350 } 351 352 if (VisitedBBs.size() != getNumBlocks()) { 353 dbgs() << "The following blocks are unreachable in the loop: "; 354 for (auto BB : Blocks) { 355 if (!VisitedBBs.count(BB)) { 356 dbgs() << *BB << "\n"; 357 } 358 } 359 assert(false && "Unreachable block in loop"); 360 } 361 362 // Check the subloops. 363 for (iterator I = begin(), E = end(); I != E; ++I) 364 // Each block in each subloop should be contained within this loop. 365 for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end(); 366 BI != BE; ++BI) { 367 assert(contains(*BI) && 368 "Loop does not contain all the blocks of a subloop!"); 369 } 370 371 // Check the parent loop pointer. 372 if (ParentLoop) { 373 assert(is_contained(*ParentLoop, this) && 374 "Loop is not a subloop of its parent!"); 375 } 376 #endif 377 } 378 379 /// verifyLoop - Verify loop structure of this loop and all nested loops. 380 template <class BlockT, class LoopT> 381 void LoopBase<BlockT, LoopT>::verifyLoopNest( 382 DenseSet<const LoopT *> *Loops) const { 383 assert(!isInvalid() && "Loop not in a valid state!"); 384 Loops->insert(static_cast<const LoopT *>(this)); 385 // Verify this loop. 386 verifyLoop(); 387 // Verify the subloops. 388 for (iterator I = begin(), E = end(); I != E; ++I) 389 (*I)->verifyLoopNest(Loops); 390 } 391 392 template <class BlockT, class LoopT> 393 void LoopBase<BlockT, LoopT>::print(raw_ostream &OS, unsigned Depth, 394 bool Verbose) const { 395 OS.indent(Depth * 2) << "Loop at depth " << getLoopDepth() << " containing: "; 396 397 BlockT *H = getHeader(); 398 for (unsigned i = 0; i < getBlocks().size(); ++i) { 399 BlockT *BB = getBlocks()[i]; 400 if (!Verbose) { 401 if (i) 402 OS << ","; 403 BB->printAsOperand(OS, false); 404 } else 405 OS << "\n"; 406 407 if (BB == H) 408 OS << "<header>"; 409 if (isLoopLatch(BB)) 410 OS << "<latch>"; 411 if (isLoopExiting(BB)) 412 OS << "<exiting>"; 413 if (Verbose) 414 BB->print(OS); 415 } 416 OS << "\n"; 417 418 for (iterator I = begin(), E = end(); I != E; ++I) 419 (*I)->print(OS, Depth + 2); 420 } 421 422 //===----------------------------------------------------------------------===// 423 /// Stable LoopInfo Analysis - Build a loop tree using stable iterators so the 424 /// result does / not depend on use list (block predecessor) order. 425 /// 426 427 /// Discover a subloop with the specified backedges such that: All blocks within 428 /// this loop are mapped to this loop or a subloop. And all subloops within this 429 /// loop have their parent loop set to this loop or a subloop. 430 template <class BlockT, class LoopT> 431 static void discoverAndMapSubloop(LoopT *L, ArrayRef<BlockT *> Backedges, 432 LoopInfoBase<BlockT, LoopT> *LI, 433 const DomTreeBase<BlockT> &DomTree) { 434 typedef GraphTraits<Inverse<BlockT *>> InvBlockTraits; 435 436 unsigned NumBlocks = 0; 437 unsigned NumSubloops = 0; 438 439 // Perform a backward CFG traversal using a worklist. 440 std::vector<BlockT *> ReverseCFGWorklist(Backedges.begin(), Backedges.end()); 441 while (!ReverseCFGWorklist.empty()) { 442 BlockT *PredBB = ReverseCFGWorklist.back(); 443 ReverseCFGWorklist.pop_back(); 444 445 LoopT *Subloop = LI->getLoopFor(PredBB); 446 if (!Subloop) { 447 if (!DomTree.isReachableFromEntry(PredBB)) 448 continue; 449 450 // This is an undiscovered block. Map it to the current loop. 451 LI->changeLoopFor(PredBB, L); 452 ++NumBlocks; 453 if (PredBB == L->getHeader()) 454 continue; 455 // Push all block predecessors on the worklist. 456 ReverseCFGWorklist.insert(ReverseCFGWorklist.end(), 457 InvBlockTraits::child_begin(PredBB), 458 InvBlockTraits::child_end(PredBB)); 459 } else { 460 // This is a discovered block. Find its outermost discovered loop. 461 while (LoopT *Parent = Subloop->getParentLoop()) 462 Subloop = Parent; 463 464 // If it is already discovered to be a subloop of this loop, continue. 465 if (Subloop == L) 466 continue; 467 468 // Discover a subloop of this loop. 469 Subloop->setParentLoop(L); 470 ++NumSubloops; 471 NumBlocks += Subloop->getBlocksVector().capacity(); 472 PredBB = Subloop->getHeader(); 473 // Continue traversal along predecessors that are not loop-back edges from 474 // within this subloop tree itself. Note that a predecessor may directly 475 // reach another subloop that is not yet discovered to be a subloop of 476 // this loop, which we must traverse. 477 for (const auto Pred : children<Inverse<BlockT *>>(PredBB)) { 478 if (LI->getLoopFor(Pred) != Subloop) 479 ReverseCFGWorklist.push_back(Pred); 480 } 481 } 482 } 483 L->getSubLoopsVector().reserve(NumSubloops); 484 L->reserveBlocks(NumBlocks); 485 } 486 487 /// Populate all loop data in a stable order during a single forward DFS. 488 template <class BlockT, class LoopT> class PopulateLoopsDFS { 489 typedef GraphTraits<BlockT *> BlockTraits; 490 typedef typename BlockTraits::ChildIteratorType SuccIterTy; 491 492 LoopInfoBase<BlockT, LoopT> *LI; 493 494 public: 495 PopulateLoopsDFS(LoopInfoBase<BlockT, LoopT> *li) : LI(li) {} 496 497 void traverse(BlockT *EntryBlock); 498 499 protected: 500 void insertIntoLoop(BlockT *Block); 501 }; 502 503 /// Top-level driver for the forward DFS within the loop. 504 template <class BlockT, class LoopT> 505 void PopulateLoopsDFS<BlockT, LoopT>::traverse(BlockT *EntryBlock) { 506 for (BlockT *BB : post_order(EntryBlock)) 507 insertIntoLoop(BB); 508 } 509 510 /// Add a single Block to its ancestor loops in PostOrder. If the block is a 511 /// subloop header, add the subloop to its parent in PostOrder, then reverse the 512 /// Block and Subloop vectors of the now complete subloop to achieve RPO. 513 template <class BlockT, class LoopT> 514 void PopulateLoopsDFS<BlockT, LoopT>::insertIntoLoop(BlockT *Block) { 515 LoopT *Subloop = LI->getLoopFor(Block); 516 if (Subloop && Block == Subloop->getHeader()) { 517 // We reach this point once per subloop after processing all the blocks in 518 // the subloop. 519 if (Subloop->getParentLoop()) 520 Subloop->getParentLoop()->getSubLoopsVector().push_back(Subloop); 521 else 522 LI->addTopLevelLoop(Subloop); 523 524 // For convenience, Blocks and Subloops are inserted in postorder. Reverse 525 // the lists, except for the loop header, which is always at the beginning. 526 Subloop->reverseBlock(1); 527 std::reverse(Subloop->getSubLoopsVector().begin(), 528 Subloop->getSubLoopsVector().end()); 529 530 Subloop = Subloop->getParentLoop(); 531 } 532 for (; Subloop; Subloop = Subloop->getParentLoop()) 533 Subloop->addBlockEntry(Block); 534 } 535 536 /// Analyze LoopInfo discovers loops during a postorder DominatorTree traversal 537 /// interleaved with backward CFG traversals within each subloop 538 /// (discoverAndMapSubloop). The backward traversal skips inner subloops, so 539 /// this part of the algorithm is linear in the number of CFG edges. Subloop and 540 /// Block vectors are then populated during a single forward CFG traversal 541 /// (PopulateLoopDFS). 542 /// 543 /// During the two CFG traversals each block is seen three times: 544 /// 1) Discovered and mapped by a reverse CFG traversal. 545 /// 2) Visited during a forward DFS CFG traversal. 546 /// 3) Reverse-inserted in the loop in postorder following forward DFS. 547 /// 548 /// The Block vectors are inclusive, so step 3 requires loop-depth number of 549 /// insertions per block. 550 template <class BlockT, class LoopT> 551 void LoopInfoBase<BlockT, LoopT>::analyze(const DomTreeBase<BlockT> &DomTree) { 552 // Postorder traversal of the dominator tree. 553 const DomTreeNodeBase<BlockT> *DomRoot = DomTree.getRootNode(); 554 for (auto DomNode : post_order(DomRoot)) { 555 556 BlockT *Header = DomNode->getBlock(); 557 SmallVector<BlockT *, 4> Backedges; 558 559 // Check each predecessor of the potential loop header. 560 for (const auto Backedge : children<Inverse<BlockT *>>(Header)) { 561 // If Header dominates predBB, this is a new loop. Collect the backedges. 562 if (DomTree.dominates(Header, Backedge) && 563 DomTree.isReachableFromEntry(Backedge)) { 564 Backedges.push_back(Backedge); 565 } 566 } 567 // Perform a backward CFG traversal to discover and map blocks in this loop. 568 if (!Backedges.empty()) { 569 LoopT *L = AllocateLoop(Header); 570 discoverAndMapSubloop(L, ArrayRef<BlockT *>(Backedges), this, DomTree); 571 } 572 } 573 // Perform a single forward CFG traversal to populate block and subloop 574 // vectors for all loops. 575 PopulateLoopsDFS<BlockT, LoopT> DFS(this); 576 DFS.traverse(DomRoot->getBlock()); 577 } 578 579 template <class BlockT, class LoopT> 580 SmallVector<LoopT *, 4> LoopInfoBase<BlockT, LoopT>::getLoopsInPreorder() { 581 SmallVector<LoopT *, 4> PreOrderLoops, PreOrderWorklist; 582 // The outer-most loop actually goes into the result in the same relative 583 // order as we walk it. But LoopInfo stores the top level loops in reverse 584 // program order so for here we reverse it to get forward program order. 585 // FIXME: If we change the order of LoopInfo we will want to remove the 586 // reverse here. 587 for (LoopT *RootL : reverse(*this)) { 588 assert(PreOrderWorklist.empty() && 589 "Must start with an empty preorder walk worklist."); 590 PreOrderWorklist.push_back(RootL); 591 do { 592 LoopT *L = PreOrderWorklist.pop_back_val(); 593 // Sub-loops are stored in forward program order, but will process the 594 // worklist backwards so append them in reverse order. 595 PreOrderWorklist.append(L->rbegin(), L->rend()); 596 PreOrderLoops.push_back(L); 597 } while (!PreOrderWorklist.empty()); 598 } 599 600 return PreOrderLoops; 601 } 602 603 template <class BlockT, class LoopT> 604 SmallVector<LoopT *, 4> 605 LoopInfoBase<BlockT, LoopT>::getLoopsInReverseSiblingPreorder() { 606 SmallVector<LoopT *, 4> PreOrderLoops, PreOrderWorklist; 607 // The outer-most loop actually goes into the result in the same relative 608 // order as we walk it. LoopInfo stores the top level loops in reverse 609 // program order so we walk in order here. 610 // FIXME: If we change the order of LoopInfo we will want to add a reverse 611 // here. 612 for (LoopT *RootL : *this) { 613 assert(PreOrderWorklist.empty() && 614 "Must start with an empty preorder walk worklist."); 615 PreOrderWorklist.push_back(RootL); 616 do { 617 LoopT *L = PreOrderWorklist.pop_back_val(); 618 // Sub-loops are stored in forward program order, but will process the 619 // worklist backwards so we can just append them in order. 620 PreOrderWorklist.append(L->begin(), L->end()); 621 PreOrderLoops.push_back(L); 622 } while (!PreOrderWorklist.empty()); 623 } 624 625 return PreOrderLoops; 626 } 627 628 // Debugging 629 template <class BlockT, class LoopT> 630 void LoopInfoBase<BlockT, LoopT>::print(raw_ostream &OS) const { 631 for (unsigned i = 0; i < TopLevelLoops.size(); ++i) 632 TopLevelLoops[i]->print(OS); 633 #if 0 634 for (DenseMap<BasicBlock*, LoopT*>::const_iterator I = BBMap.begin(), 635 E = BBMap.end(); I != E; ++I) 636 OS << "BB '" << I->first->getName() << "' level = " 637 << I->second->getLoopDepth() << "\n"; 638 #endif 639 } 640 641 template <typename T> 642 bool compareVectors(std::vector<T> &BB1, std::vector<T> &BB2) { 643 llvm::sort(BB1.begin(), BB1.end()); 644 llvm::sort(BB2.begin(), BB2.end()); 645 return BB1 == BB2; 646 } 647 648 template <class BlockT, class LoopT> 649 void addInnerLoopsToHeadersMap(DenseMap<BlockT *, const LoopT *> &LoopHeaders, 650 const LoopInfoBase<BlockT, LoopT> &LI, 651 const LoopT &L) { 652 LoopHeaders[L.getHeader()] = &L; 653 for (LoopT *SL : L) 654 addInnerLoopsToHeadersMap(LoopHeaders, LI, *SL); 655 } 656 657 #ifndef NDEBUG 658 template <class BlockT, class LoopT> 659 static void compareLoops(const LoopT *L, const LoopT *OtherL, 660 DenseMap<BlockT *, const LoopT *> &OtherLoopHeaders) { 661 BlockT *H = L->getHeader(); 662 BlockT *OtherH = OtherL->getHeader(); 663 assert(H == OtherH && 664 "Mismatched headers even though found in the same map entry!"); 665 666 assert(L->getLoopDepth() == OtherL->getLoopDepth() && 667 "Mismatched loop depth!"); 668 const LoopT *ParentL = L, *OtherParentL = OtherL; 669 do { 670 assert(ParentL->getHeader() == OtherParentL->getHeader() && 671 "Mismatched parent loop headers!"); 672 ParentL = ParentL->getParentLoop(); 673 OtherParentL = OtherParentL->getParentLoop(); 674 } while (ParentL); 675 676 for (const LoopT *SubL : *L) { 677 BlockT *SubH = SubL->getHeader(); 678 const LoopT *OtherSubL = OtherLoopHeaders.lookup(SubH); 679 assert(OtherSubL && "Inner loop is missing in computed loop info!"); 680 OtherLoopHeaders.erase(SubH); 681 compareLoops(SubL, OtherSubL, OtherLoopHeaders); 682 } 683 684 std::vector<BlockT *> BBs = L->getBlocks(); 685 std::vector<BlockT *> OtherBBs = OtherL->getBlocks(); 686 assert(compareVectors(BBs, OtherBBs) && 687 "Mismatched basic blocks in the loops!"); 688 689 const SmallPtrSetImpl<const BlockT *> &BlocksSet = L->getBlocksSet(); 690 const SmallPtrSetImpl<const BlockT *> &OtherBlocksSet = L->getBlocksSet(); 691 assert(BlocksSet.size() == OtherBlocksSet.size() && 692 std::all_of(BlocksSet.begin(), BlocksSet.end(), 693 [&OtherBlocksSet](const BlockT *BB) { 694 return OtherBlocksSet.count(BB); 695 }) && 696 "Mismatched basic blocks in BlocksSets!"); 697 } 698 #endif 699 700 template <class BlockT, class LoopT> 701 void LoopInfoBase<BlockT, LoopT>::verify( 702 const DomTreeBase<BlockT> &DomTree) const { 703 DenseSet<const LoopT *> Loops; 704 for (iterator I = begin(), E = end(); I != E; ++I) { 705 assert(!(*I)->getParentLoop() && "Top-level loop has a parent!"); 706 (*I)->verifyLoopNest(&Loops); 707 } 708 709 // Verify that blocks are mapped to valid loops. 710 #ifndef NDEBUG 711 for (auto &Entry : BBMap) { 712 const BlockT *BB = Entry.first; 713 LoopT *L = Entry.second; 714 assert(Loops.count(L) && "orphaned loop"); 715 assert(L->contains(BB) && "orphaned block"); 716 for (LoopT *ChildLoop : *L) 717 assert(!ChildLoop->contains(BB) && 718 "BBMap should point to the innermost loop containing BB"); 719 } 720 721 // Recompute LoopInfo to verify loops structure. 722 LoopInfoBase<BlockT, LoopT> OtherLI; 723 OtherLI.analyze(DomTree); 724 725 // Build a map we can use to move from our LI to the computed one. This 726 // allows us to ignore the particular order in any layer of the loop forest 727 // while still comparing the structure. 728 DenseMap<BlockT *, const LoopT *> OtherLoopHeaders; 729 for (LoopT *L : OtherLI) 730 addInnerLoopsToHeadersMap(OtherLoopHeaders, OtherLI, *L); 731 732 // Walk the top level loops and ensure there is a corresponding top-level 733 // loop in the computed version and then recursively compare those loop 734 // nests. 735 for (LoopT *L : *this) { 736 BlockT *Header = L->getHeader(); 737 const LoopT *OtherL = OtherLoopHeaders.lookup(Header); 738 assert(OtherL && "Top level loop is missing in computed loop info!"); 739 // Now that we've matched this loop, erase its header from the map. 740 OtherLoopHeaders.erase(Header); 741 // And recursively compare these loops. 742 compareLoops(L, OtherL, OtherLoopHeaders); 743 } 744 745 // Any remaining entries in the map are loops which were found when computing 746 // a fresh LoopInfo but not present in the current one. 747 if (!OtherLoopHeaders.empty()) { 748 for (const auto &HeaderAndLoop : OtherLoopHeaders) 749 dbgs() << "Found new loop: " << *HeaderAndLoop.second << "\n"; 750 llvm_unreachable("Found new loops when recomputing LoopInfo!"); 751 } 752 #endif 753 } 754 755 } // End llvm namespace 756 757 #endif 758