LoopInfoImpl.h revision 360784
1//===- llvm/Analysis/LoopInfoImpl.h - Natural Loop Calculator ---*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8// 9// This is the generic implementation of LoopInfo used for both Loops and 10// MachineLoops. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_ANALYSIS_LOOPINFOIMPL_H 15#define LLVM_ANALYSIS_LOOPINFOIMPL_H 16 17#include "llvm/ADT/DepthFirstIterator.h" 18#include "llvm/ADT/PostOrderIterator.h" 19#include "llvm/ADT/STLExtras.h" 20#include "llvm/ADT/SetVector.h" 21#include "llvm/Analysis/LoopInfo.h" 22#include "llvm/IR/Dominators.h" 23 24namespace llvm { 25 26//===----------------------------------------------------------------------===// 27// APIs for simple analysis of the loop. See header notes. 28 29/// getExitingBlocks - Return all blocks inside the loop that have successors 30/// outside of the loop. These are the blocks _inside of the current loop_ 31/// which branch out. The returned list is always unique. 32/// 33template <class BlockT, class LoopT> 34void LoopBase<BlockT, LoopT>::getExitingBlocks( 35 SmallVectorImpl<BlockT *> &ExitingBlocks) const { 36 assert(!isInvalid() && "Loop not in a valid state!"); 37 for (const auto BB : blocks()) 38 for (auto *Succ : children<BlockT *>(BB)) 39 if (!contains(Succ)) { 40 // Not in current loop? It must be an exit block. 41 ExitingBlocks.push_back(BB); 42 break; 43 } 44} 45 46/// getExitingBlock - If getExitingBlocks would return exactly one block, 47/// return that block. Otherwise return null. 48template <class BlockT, class LoopT> 49BlockT *LoopBase<BlockT, LoopT>::getExitingBlock() const { 50 assert(!isInvalid() && "Loop not in a valid state!"); 51 SmallVector<BlockT *, 8> ExitingBlocks; 52 getExitingBlocks(ExitingBlocks); 53 if (ExitingBlocks.size() == 1) 54 return ExitingBlocks[0]; 55 return nullptr; 56} 57 58/// getExitBlocks - Return all of the successor blocks of this loop. These 59/// are the blocks _outside of the current loop_ which are branched to. 60/// 61template <class BlockT, class LoopT> 62void LoopBase<BlockT, LoopT>::getExitBlocks( 63 SmallVectorImpl<BlockT *> &ExitBlocks) const { 64 assert(!isInvalid() && "Loop not in a valid state!"); 65 for (const auto BB : blocks()) 66 for (auto *Succ : children<BlockT *>(BB)) 67 if (!contains(Succ)) 68 // Not in current loop? It must be an exit block. 69 ExitBlocks.push_back(Succ); 70} 71 72/// getExitBlock - If getExitBlocks would return exactly one block, 73/// return that block. Otherwise return null. 74template <class BlockT, class LoopT> 75BlockT *LoopBase<BlockT, LoopT>::getExitBlock() const { 76 assert(!isInvalid() && "Loop not in a valid state!"); 77 SmallVector<BlockT *, 8> ExitBlocks; 78 getExitBlocks(ExitBlocks); 79 if (ExitBlocks.size() == 1) 80 return ExitBlocks[0]; 81 return nullptr; 82} 83 84template <class BlockT, class LoopT> 85bool LoopBase<BlockT, LoopT>::hasDedicatedExits() const { 86 // Each predecessor of each exit block of a normal loop is contained 87 // within the loop. 88 SmallVector<BlockT *, 4> UniqueExitBlocks; 89 getUniqueExitBlocks(UniqueExitBlocks); 90 for (BlockT *EB : UniqueExitBlocks) 91 for (BlockT *Predecessor : children<Inverse<BlockT *>>(EB)) 92 if (!contains(Predecessor)) 93 return false; 94 // All the requirements are met. 95 return true; 96} 97 98// Helper function to get unique loop exits. Pred is a predicate pointing to 99// BasicBlocks in a loop which should be considered to find loop exits. 100template <class BlockT, class LoopT, typename PredicateT> 101void getUniqueExitBlocksHelper(const LoopT *L, 102 SmallVectorImpl<BlockT *> &ExitBlocks, 103 PredicateT Pred) { 104 assert(!L->isInvalid() && "Loop not in a valid state!"); 105 SmallPtrSet<BlockT *, 32> Visited; 106 auto Filtered = make_filter_range(L->blocks(), Pred); 107 for (BlockT *BB : Filtered) 108 for (BlockT *Successor : children<BlockT *>(BB)) 109 if (!L->contains(Successor)) 110 if (Visited.insert(Successor).second) 111 ExitBlocks.push_back(Successor); 112} 113 114template <class BlockT, class LoopT> 115void LoopBase<BlockT, LoopT>::getUniqueExitBlocks( 116 SmallVectorImpl<BlockT *> &ExitBlocks) const { 117 getUniqueExitBlocksHelper(this, ExitBlocks, 118 [](const BlockT *BB) { return true; }); 119} 120 121template <class BlockT, class LoopT> 122void LoopBase<BlockT, LoopT>::getUniqueNonLatchExitBlocks( 123 SmallVectorImpl<BlockT *> &ExitBlocks) const { 124 const BlockT *Latch = getLoopLatch(); 125 assert(Latch && "Latch block must exists"); 126 getUniqueExitBlocksHelper(this, ExitBlocks, 127 [Latch](const BlockT *BB) { return BB != Latch; }); 128} 129 130template <class BlockT, class LoopT> 131BlockT *LoopBase<BlockT, LoopT>::getUniqueExitBlock() const { 132 SmallVector<BlockT *, 8> UniqueExitBlocks; 133 getUniqueExitBlocks(UniqueExitBlocks); 134 if (UniqueExitBlocks.size() == 1) 135 return UniqueExitBlocks[0]; 136 return nullptr; 137} 138 139/// getExitEdges - Return all pairs of (_inside_block_,_outside_block_). 140template <class BlockT, class LoopT> 141void LoopBase<BlockT, LoopT>::getExitEdges( 142 SmallVectorImpl<Edge> &ExitEdges) const { 143 assert(!isInvalid() && "Loop not in a valid state!"); 144 for (const auto BB : blocks()) 145 for (auto *Succ : children<BlockT *>(BB)) 146 if (!contains(Succ)) 147 // Not in current loop? It must be an exit block. 148 ExitEdges.emplace_back(BB, Succ); 149} 150 151/// getLoopPreheader - If there is a preheader for this loop, return it. A 152/// loop has a preheader if there is only one edge to the header of the loop 153/// from outside of the loop and it is legal to hoist instructions into the 154/// predecessor. If this is the case, the block branching to the header of the 155/// loop is the preheader node. 156/// 157/// This method returns null if there is no preheader for the loop. 158/// 159template <class BlockT, class LoopT> 160BlockT *LoopBase<BlockT, LoopT>::getLoopPreheader() const { 161 assert(!isInvalid() && "Loop not in a valid state!"); 162 // Keep track of nodes outside the loop branching to the header... 163 BlockT *Out = getLoopPredecessor(); 164 if (!Out) 165 return nullptr; 166 167 // Make sure we are allowed to hoist instructions into the predecessor. 168 if (!Out->isLegalToHoistInto()) 169 return nullptr; 170 171 // Make sure there is only one exit out of the preheader. 172 typedef GraphTraits<BlockT *> BlockTraits; 173 typename BlockTraits::ChildIteratorType SI = BlockTraits::child_begin(Out); 174 ++SI; 175 if (SI != BlockTraits::child_end(Out)) 176 return nullptr; // Multiple exits from the block, must not be a preheader. 177 178 // The predecessor has exactly one successor, so it is a preheader. 179 return Out; 180} 181 182/// getLoopPredecessor - If the given loop's header has exactly one unique 183/// predecessor outside the loop, return it. Otherwise return null. 184/// This is less strict that the loop "preheader" concept, which requires 185/// the predecessor to have exactly one successor. 186/// 187template <class BlockT, class LoopT> 188BlockT *LoopBase<BlockT, LoopT>::getLoopPredecessor() const { 189 assert(!isInvalid() && "Loop not in a valid state!"); 190 // Keep track of nodes outside the loop branching to the header... 191 BlockT *Out = nullptr; 192 193 // Loop over the predecessors of the header node... 194 BlockT *Header = getHeader(); 195 for (const auto Pred : children<Inverse<BlockT *>>(Header)) { 196 if (!contains(Pred)) { // If the block is not in the loop... 197 if (Out && Out != Pred) 198 return nullptr; // Multiple predecessors outside the loop 199 Out = Pred; 200 } 201 } 202 203 return Out; 204} 205 206/// getLoopLatch - If there is a single latch block for this loop, return it. 207/// A latch block is a block that contains a branch back to the header. 208template <class BlockT, class LoopT> 209BlockT *LoopBase<BlockT, LoopT>::getLoopLatch() const { 210 assert(!isInvalid() && "Loop not in a valid state!"); 211 BlockT *Header = getHeader(); 212 BlockT *Latch = nullptr; 213 for (const auto Pred : children<Inverse<BlockT *>>(Header)) { 214 if (contains(Pred)) { 215 if (Latch) 216 return nullptr; 217 Latch = Pred; 218 } 219 } 220 221 return Latch; 222} 223 224//===----------------------------------------------------------------------===// 225// APIs for updating loop information after changing the CFG 226// 227 228/// addBasicBlockToLoop - This method is used by other analyses to update loop 229/// information. NewBB is set to be a new member of the current loop. 230/// Because of this, it is added as a member of all parent loops, and is added 231/// to the specified LoopInfo object as being in the current basic block. It 232/// is not valid to replace the loop header with this method. 233/// 234template <class BlockT, class LoopT> 235void LoopBase<BlockT, LoopT>::addBasicBlockToLoop( 236 BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LIB) { 237 assert(!isInvalid() && "Loop not in a valid state!"); 238#ifndef NDEBUG 239 if (!Blocks.empty()) { 240 auto SameHeader = LIB[getHeader()]; 241 assert(contains(SameHeader) && getHeader() == SameHeader->getHeader() && 242 "Incorrect LI specified for this loop!"); 243 } 244#endif 245 assert(NewBB && "Cannot add a null basic block to the loop!"); 246 assert(!LIB[NewBB] && "BasicBlock already in the loop!"); 247 248 LoopT *L = static_cast<LoopT *>(this); 249 250 // Add the loop mapping to the LoopInfo object... 251 LIB.BBMap[NewBB] = L; 252 253 // Add the basic block to this loop and all parent loops... 254 while (L) { 255 L->addBlockEntry(NewBB); 256 L = L->getParentLoop(); 257 } 258} 259 260/// replaceChildLoopWith - This is used when splitting loops up. It replaces 261/// the OldChild entry in our children list with NewChild, and updates the 262/// parent pointer of OldChild to be null and the NewChild to be this loop. 263/// This updates the loop depth of the new child. 264template <class BlockT, class LoopT> 265void LoopBase<BlockT, LoopT>::replaceChildLoopWith(LoopT *OldChild, 266 LoopT *NewChild) { 267 assert(!isInvalid() && "Loop not in a valid state!"); 268 assert(OldChild->ParentLoop == this && "This loop is already broken!"); 269 assert(!NewChild->ParentLoop && "NewChild already has a parent!"); 270 typename std::vector<LoopT *>::iterator I = find(SubLoops, OldChild); 271 assert(I != SubLoops.end() && "OldChild not in loop!"); 272 *I = NewChild; 273 OldChild->ParentLoop = nullptr; 274 NewChild->ParentLoop = static_cast<LoopT *>(this); 275} 276 277/// verifyLoop - Verify loop structure 278template <class BlockT, class LoopT> 279void LoopBase<BlockT, LoopT>::verifyLoop() const { 280 assert(!isInvalid() && "Loop not in a valid state!"); 281#ifndef NDEBUG 282 assert(!Blocks.empty() && "Loop header is missing"); 283 284 // Setup for using a depth-first iterator to visit every block in the loop. 285 SmallVector<BlockT *, 8> ExitBBs; 286 getExitBlocks(ExitBBs); 287 df_iterator_default_set<BlockT *> VisitSet; 288 VisitSet.insert(ExitBBs.begin(), ExitBBs.end()); 289 df_ext_iterator<BlockT *, df_iterator_default_set<BlockT *>> 290 BI = df_ext_begin(getHeader(), VisitSet), 291 BE = df_ext_end(getHeader(), VisitSet); 292 293 // Keep track of the BBs visited. 294 SmallPtrSet<BlockT *, 8> VisitedBBs; 295 296 // Check the individual blocks. 297 for (; BI != BE; ++BI) { 298 BlockT *BB = *BI; 299 300 assert(std::any_of(GraphTraits<BlockT *>::child_begin(BB), 301 GraphTraits<BlockT *>::child_end(BB), 302 [&](BlockT *B) { return contains(B); }) && 303 "Loop block has no in-loop successors!"); 304 305 assert(std::any_of(GraphTraits<Inverse<BlockT *>>::child_begin(BB), 306 GraphTraits<Inverse<BlockT *>>::child_end(BB), 307 [&](BlockT *B) { return contains(B); }) && 308 "Loop block has no in-loop predecessors!"); 309 310 SmallVector<BlockT *, 2> OutsideLoopPreds; 311 std::for_each(GraphTraits<Inverse<BlockT *>>::child_begin(BB), 312 GraphTraits<Inverse<BlockT *>>::child_end(BB), 313 [&](BlockT *B) { 314 if (!contains(B)) 315 OutsideLoopPreds.push_back(B); 316 }); 317 318 if (BB == getHeader()) { 319 assert(!OutsideLoopPreds.empty() && "Loop is unreachable!"); 320 } else if (!OutsideLoopPreds.empty()) { 321 // A non-header loop shouldn't be reachable from outside the loop, 322 // though it is permitted if the predecessor is not itself actually 323 // reachable. 324 BlockT *EntryBB = &BB->getParent()->front(); 325 for (BlockT *CB : depth_first(EntryBB)) 326 for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i) 327 assert(CB != OutsideLoopPreds[i] && 328 "Loop has multiple entry points!"); 329 } 330 assert(BB != &getHeader()->getParent()->front() && 331 "Loop contains function entry block!"); 332 333 VisitedBBs.insert(BB); 334 } 335 336 if (VisitedBBs.size() != getNumBlocks()) { 337 dbgs() << "The following blocks are unreachable in the loop: "; 338 for (auto BB : Blocks) { 339 if (!VisitedBBs.count(BB)) { 340 dbgs() << *BB << "\n"; 341 } 342 } 343 assert(false && "Unreachable block in loop"); 344 } 345 346 // Check the subloops. 347 for (iterator I = begin(), E = end(); I != E; ++I) 348 // Each block in each subloop should be contained within this loop. 349 for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end(); 350 BI != BE; ++BI) { 351 assert(contains(*BI) && 352 "Loop does not contain all the blocks of a subloop!"); 353 } 354 355 // Check the parent loop pointer. 356 if (ParentLoop) { 357 assert(is_contained(*ParentLoop, this) && 358 "Loop is not a subloop of its parent!"); 359 } 360#endif 361} 362 363/// verifyLoop - Verify loop structure of this loop and all nested loops. 364template <class BlockT, class LoopT> 365void LoopBase<BlockT, LoopT>::verifyLoopNest( 366 DenseSet<const LoopT *> *Loops) const { 367 assert(!isInvalid() && "Loop not in a valid state!"); 368 Loops->insert(static_cast<const LoopT *>(this)); 369 // Verify this loop. 370 verifyLoop(); 371 // Verify the subloops. 372 for (iterator I = begin(), E = end(); I != E; ++I) 373 (*I)->verifyLoopNest(Loops); 374} 375 376template <class BlockT, class LoopT> 377void LoopBase<BlockT, LoopT>::print(raw_ostream &OS, unsigned Depth, 378 bool Verbose) const { 379 OS.indent(Depth * 2); 380 if (static_cast<const LoopT *>(this)->isAnnotatedParallel()) 381 OS << "Parallel "; 382 OS << "Loop at depth " << getLoopDepth() << " containing: "; 383 384 BlockT *H = getHeader(); 385 for (unsigned i = 0; i < getBlocks().size(); ++i) { 386 BlockT *BB = getBlocks()[i]; 387 if (!Verbose) { 388 if (i) 389 OS << ","; 390 BB->printAsOperand(OS, false); 391 } else 392 OS << "\n"; 393 394 if (BB == H) 395 OS << "<header>"; 396 if (isLoopLatch(BB)) 397 OS << "<latch>"; 398 if (isLoopExiting(BB)) 399 OS << "<exiting>"; 400 if (Verbose) 401 BB->print(OS); 402 } 403 OS << "\n"; 404 405 for (iterator I = begin(), E = end(); I != E; ++I) 406 (*I)->print(OS, Depth + 2); 407} 408 409//===----------------------------------------------------------------------===// 410/// Stable LoopInfo Analysis - Build a loop tree using stable iterators so the 411/// result does / not depend on use list (block predecessor) order. 412/// 413 414/// Discover a subloop with the specified backedges such that: All blocks within 415/// this loop are mapped to this loop or a subloop. And all subloops within this 416/// loop have their parent loop set to this loop or a subloop. 417template <class BlockT, class LoopT> 418static void discoverAndMapSubloop(LoopT *L, ArrayRef<BlockT *> Backedges, 419 LoopInfoBase<BlockT, LoopT> *LI, 420 const DomTreeBase<BlockT> &DomTree) { 421 typedef GraphTraits<Inverse<BlockT *>> InvBlockTraits; 422 423 unsigned NumBlocks = 0; 424 unsigned NumSubloops = 0; 425 426 // Perform a backward CFG traversal using a worklist. 427 std::vector<BlockT *> ReverseCFGWorklist(Backedges.begin(), Backedges.end()); 428 while (!ReverseCFGWorklist.empty()) { 429 BlockT *PredBB = ReverseCFGWorklist.back(); 430 ReverseCFGWorklist.pop_back(); 431 432 LoopT *Subloop = LI->getLoopFor(PredBB); 433 if (!Subloop) { 434 if (!DomTree.isReachableFromEntry(PredBB)) 435 continue; 436 437 // This is an undiscovered block. Map it to the current loop. 438 LI->changeLoopFor(PredBB, L); 439 ++NumBlocks; 440 if (PredBB == L->getHeader()) 441 continue; 442 // Push all block predecessors on the worklist. 443 ReverseCFGWorklist.insert(ReverseCFGWorklist.end(), 444 InvBlockTraits::child_begin(PredBB), 445 InvBlockTraits::child_end(PredBB)); 446 } else { 447 // This is a discovered block. Find its outermost discovered loop. 448 while (LoopT *Parent = Subloop->getParentLoop()) 449 Subloop = Parent; 450 451 // If it is already discovered to be a subloop of this loop, continue. 452 if (Subloop == L) 453 continue; 454 455 // Discover a subloop of this loop. 456 Subloop->setParentLoop(L); 457 ++NumSubloops; 458 NumBlocks += Subloop->getBlocksVector().capacity(); 459 PredBB = Subloop->getHeader(); 460 // Continue traversal along predecessors that are not loop-back edges from 461 // within this subloop tree itself. Note that a predecessor may directly 462 // reach another subloop that is not yet discovered to be a subloop of 463 // this loop, which we must traverse. 464 for (const auto Pred : children<Inverse<BlockT *>>(PredBB)) { 465 if (LI->getLoopFor(Pred) != Subloop) 466 ReverseCFGWorklist.push_back(Pred); 467 } 468 } 469 } 470 L->getSubLoopsVector().reserve(NumSubloops); 471 L->reserveBlocks(NumBlocks); 472} 473 474/// Populate all loop data in a stable order during a single forward DFS. 475template <class BlockT, class LoopT> class PopulateLoopsDFS { 476 typedef GraphTraits<BlockT *> BlockTraits; 477 typedef typename BlockTraits::ChildIteratorType SuccIterTy; 478 479 LoopInfoBase<BlockT, LoopT> *LI; 480 481public: 482 PopulateLoopsDFS(LoopInfoBase<BlockT, LoopT> *li) : LI(li) {} 483 484 void traverse(BlockT *EntryBlock); 485 486protected: 487 void insertIntoLoop(BlockT *Block); 488}; 489 490/// Top-level driver for the forward DFS within the loop. 491template <class BlockT, class LoopT> 492void PopulateLoopsDFS<BlockT, LoopT>::traverse(BlockT *EntryBlock) { 493 for (BlockT *BB : post_order(EntryBlock)) 494 insertIntoLoop(BB); 495} 496 497/// Add a single Block to its ancestor loops in PostOrder. If the block is a 498/// subloop header, add the subloop to its parent in PostOrder, then reverse the 499/// Block and Subloop vectors of the now complete subloop to achieve RPO. 500template <class BlockT, class LoopT> 501void PopulateLoopsDFS<BlockT, LoopT>::insertIntoLoop(BlockT *Block) { 502 LoopT *Subloop = LI->getLoopFor(Block); 503 if (Subloop && Block == Subloop->getHeader()) { 504 // We reach this point once per subloop after processing all the blocks in 505 // the subloop. 506 if (Subloop->getParentLoop()) 507 Subloop->getParentLoop()->getSubLoopsVector().push_back(Subloop); 508 else 509 LI->addTopLevelLoop(Subloop); 510 511 // For convenience, Blocks and Subloops are inserted in postorder. Reverse 512 // the lists, except for the loop header, which is always at the beginning. 513 Subloop->reverseBlock(1); 514 std::reverse(Subloop->getSubLoopsVector().begin(), 515 Subloop->getSubLoopsVector().end()); 516 517 Subloop = Subloop->getParentLoop(); 518 } 519 for (; Subloop; Subloop = Subloop->getParentLoop()) 520 Subloop->addBlockEntry(Block); 521} 522 523/// Analyze LoopInfo discovers loops during a postorder DominatorTree traversal 524/// interleaved with backward CFG traversals within each subloop 525/// (discoverAndMapSubloop). The backward traversal skips inner subloops, so 526/// this part of the algorithm is linear in the number of CFG edges. Subloop and 527/// Block vectors are then populated during a single forward CFG traversal 528/// (PopulateLoopDFS). 529/// 530/// During the two CFG traversals each block is seen three times: 531/// 1) Discovered and mapped by a reverse CFG traversal. 532/// 2) Visited during a forward DFS CFG traversal. 533/// 3) Reverse-inserted in the loop in postorder following forward DFS. 534/// 535/// The Block vectors are inclusive, so step 3 requires loop-depth number of 536/// insertions per block. 537template <class BlockT, class LoopT> 538void LoopInfoBase<BlockT, LoopT>::analyze(const DomTreeBase<BlockT> &DomTree) { 539 // Postorder traversal of the dominator tree. 540 const DomTreeNodeBase<BlockT> *DomRoot = DomTree.getRootNode(); 541 for (auto DomNode : post_order(DomRoot)) { 542 543 BlockT *Header = DomNode->getBlock(); 544 SmallVector<BlockT *, 4> Backedges; 545 546 // Check each predecessor of the potential loop header. 547 for (const auto Backedge : children<Inverse<BlockT *>>(Header)) { 548 // If Header dominates predBB, this is a new loop. Collect the backedges. 549 if (DomTree.dominates(Header, Backedge) && 550 DomTree.isReachableFromEntry(Backedge)) { 551 Backedges.push_back(Backedge); 552 } 553 } 554 // Perform a backward CFG traversal to discover and map blocks in this loop. 555 if (!Backedges.empty()) { 556 LoopT *L = AllocateLoop(Header); 557 discoverAndMapSubloop(L, ArrayRef<BlockT *>(Backedges), this, DomTree); 558 } 559 } 560 // Perform a single forward CFG traversal to populate block and subloop 561 // vectors for all loops. 562 PopulateLoopsDFS<BlockT, LoopT> DFS(this); 563 DFS.traverse(DomRoot->getBlock()); 564} 565 566template <class BlockT, class LoopT> 567SmallVector<LoopT *, 4> LoopInfoBase<BlockT, LoopT>::getLoopsInPreorder() { 568 SmallVector<LoopT *, 4> PreOrderLoops, PreOrderWorklist; 569 // The outer-most loop actually goes into the result in the same relative 570 // order as we walk it. But LoopInfo stores the top level loops in reverse 571 // program order so for here we reverse it to get forward program order. 572 // FIXME: If we change the order of LoopInfo we will want to remove the 573 // reverse here. 574 for (LoopT *RootL : reverse(*this)) { 575 auto PreOrderLoopsInRootL = RootL->getLoopsInPreorder(); 576 PreOrderLoops.append(PreOrderLoopsInRootL.begin(), 577 PreOrderLoopsInRootL.end()); 578 } 579 580 return PreOrderLoops; 581} 582 583template <class BlockT, class LoopT> 584SmallVector<LoopT *, 4> 585LoopInfoBase<BlockT, LoopT>::getLoopsInReverseSiblingPreorder() { 586 SmallVector<LoopT *, 4> PreOrderLoops, PreOrderWorklist; 587 // The outer-most loop actually goes into the result in the same relative 588 // order as we walk it. LoopInfo stores the top level loops in reverse 589 // program order so we walk in order here. 590 // FIXME: If we change the order of LoopInfo we will want to add a reverse 591 // here. 592 for (LoopT *RootL : *this) { 593 assert(PreOrderWorklist.empty() && 594 "Must start with an empty preorder walk worklist."); 595 PreOrderWorklist.push_back(RootL); 596 do { 597 LoopT *L = PreOrderWorklist.pop_back_val(); 598 // Sub-loops are stored in forward program order, but will process the 599 // worklist backwards so we can just append them in order. 600 PreOrderWorklist.append(L->begin(), L->end()); 601 PreOrderLoops.push_back(L); 602 } while (!PreOrderWorklist.empty()); 603 } 604 605 return PreOrderLoops; 606} 607 608// Debugging 609template <class BlockT, class LoopT> 610void LoopInfoBase<BlockT, LoopT>::print(raw_ostream &OS) const { 611 for (unsigned i = 0; i < TopLevelLoops.size(); ++i) 612 TopLevelLoops[i]->print(OS); 613#if 0 614 for (DenseMap<BasicBlock*, LoopT*>::const_iterator I = BBMap.begin(), 615 E = BBMap.end(); I != E; ++I) 616 OS << "BB '" << I->first->getName() << "' level = " 617 << I->second->getLoopDepth() << "\n"; 618#endif 619} 620 621template <typename T> 622bool compareVectors(std::vector<T> &BB1, std::vector<T> &BB2) { 623 llvm::sort(BB1); 624 llvm::sort(BB2); 625 return BB1 == BB2; 626} 627 628template <class BlockT, class LoopT> 629void addInnerLoopsToHeadersMap(DenseMap<BlockT *, const LoopT *> &LoopHeaders, 630 const LoopInfoBase<BlockT, LoopT> &LI, 631 const LoopT &L) { 632 LoopHeaders[L.getHeader()] = &L; 633 for (LoopT *SL : L) 634 addInnerLoopsToHeadersMap(LoopHeaders, LI, *SL); 635} 636 637#ifndef NDEBUG 638template <class BlockT, class LoopT> 639static void compareLoops(const LoopT *L, const LoopT *OtherL, 640 DenseMap<BlockT *, const LoopT *> &OtherLoopHeaders) { 641 BlockT *H = L->getHeader(); 642 BlockT *OtherH = OtherL->getHeader(); 643 assert(H == OtherH && 644 "Mismatched headers even though found in the same map entry!"); 645 646 assert(L->getLoopDepth() == OtherL->getLoopDepth() && 647 "Mismatched loop depth!"); 648 const LoopT *ParentL = L, *OtherParentL = OtherL; 649 do { 650 assert(ParentL->getHeader() == OtherParentL->getHeader() && 651 "Mismatched parent loop headers!"); 652 ParentL = ParentL->getParentLoop(); 653 OtherParentL = OtherParentL->getParentLoop(); 654 } while (ParentL); 655 656 for (const LoopT *SubL : *L) { 657 BlockT *SubH = SubL->getHeader(); 658 const LoopT *OtherSubL = OtherLoopHeaders.lookup(SubH); 659 assert(OtherSubL && "Inner loop is missing in computed loop info!"); 660 OtherLoopHeaders.erase(SubH); 661 compareLoops(SubL, OtherSubL, OtherLoopHeaders); 662 } 663 664 std::vector<BlockT *> BBs = L->getBlocks(); 665 std::vector<BlockT *> OtherBBs = OtherL->getBlocks(); 666 assert(compareVectors(BBs, OtherBBs) && 667 "Mismatched basic blocks in the loops!"); 668 669 const SmallPtrSetImpl<const BlockT *> &BlocksSet = L->getBlocksSet(); 670 const SmallPtrSetImpl<const BlockT *> &OtherBlocksSet = L->getBlocksSet(); 671 assert(BlocksSet.size() == OtherBlocksSet.size() && 672 std::all_of(BlocksSet.begin(), BlocksSet.end(), 673 [&OtherBlocksSet](const BlockT *BB) { 674 return OtherBlocksSet.count(BB); 675 }) && 676 "Mismatched basic blocks in BlocksSets!"); 677} 678#endif 679 680template <class BlockT, class LoopT> 681void LoopInfoBase<BlockT, LoopT>::verify( 682 const DomTreeBase<BlockT> &DomTree) const { 683 DenseSet<const LoopT *> Loops; 684 for (iterator I = begin(), E = end(); I != E; ++I) { 685 assert(!(*I)->getParentLoop() && "Top-level loop has a parent!"); 686 (*I)->verifyLoopNest(&Loops); 687 } 688 689// Verify that blocks are mapped to valid loops. 690#ifndef NDEBUG 691 for (auto &Entry : BBMap) { 692 const BlockT *BB = Entry.first; 693 LoopT *L = Entry.second; 694 assert(Loops.count(L) && "orphaned loop"); 695 assert(L->contains(BB) && "orphaned block"); 696 for (LoopT *ChildLoop : *L) 697 assert(!ChildLoop->contains(BB) && 698 "BBMap should point to the innermost loop containing BB"); 699 } 700 701 // Recompute LoopInfo to verify loops structure. 702 LoopInfoBase<BlockT, LoopT> OtherLI; 703 OtherLI.analyze(DomTree); 704 705 // Build a map we can use to move from our LI to the computed one. This 706 // allows us to ignore the particular order in any layer of the loop forest 707 // while still comparing the structure. 708 DenseMap<BlockT *, const LoopT *> OtherLoopHeaders; 709 for (LoopT *L : OtherLI) 710 addInnerLoopsToHeadersMap(OtherLoopHeaders, OtherLI, *L); 711 712 // Walk the top level loops and ensure there is a corresponding top-level 713 // loop in the computed version and then recursively compare those loop 714 // nests. 715 for (LoopT *L : *this) { 716 BlockT *Header = L->getHeader(); 717 const LoopT *OtherL = OtherLoopHeaders.lookup(Header); 718 assert(OtherL && "Top level loop is missing in computed loop info!"); 719 // Now that we've matched this loop, erase its header from the map. 720 OtherLoopHeaders.erase(Header); 721 // And recursively compare these loops. 722 compareLoops(L, OtherL, OtherLoopHeaders); 723 } 724 725 // Any remaining entries in the map are loops which were found when computing 726 // a fresh LoopInfo but not present in the current one. 727 if (!OtherLoopHeaders.empty()) { 728 for (const auto &HeaderAndLoop : OtherLoopHeaders) 729 dbgs() << "Found new loop: " << *HeaderAndLoop.second << "\n"; 730 llvm_unreachable("Found new loops when recomputing LoopInfo!"); 731 } 732#endif 733} 734 735} // End llvm namespace 736 737#endif 738