LoopUnswitch.cpp revision 3e8b6631e67e01e4960a7ba4668a50c596607473
1//===-- LoopUnswitch.cpp - Hoist loop-invariant conditionals in loop ------===// 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 pass transforms loops that contain branches on loop-invariant conditions 11// to have multiple loops. For example, it turns the left into the right code: 12// 13// for (...) if (lic) 14// A for (...) 15// if (lic) A; B; C 16// B else 17// C for (...) 18// A; C 19// 20// This can increase the size of the code exponentially (doubling it every time 21// a loop is unswitched) so we only unswitch if the resultant code will be 22// smaller than a threshold. 23// 24// This pass expects LICM to be run before it to hoist invariant conditions out 25// of the loop, to make the unswitching opportunity obvious. 26// 27//===----------------------------------------------------------------------===// 28 29#define DEBUG_TYPE "loop-unswitch" 30#include "llvm/Transforms/Scalar.h" 31#include "llvm/Constants.h" 32#include "llvm/DerivedTypes.h" 33#include "llvm/Function.h" 34#include "llvm/Instructions.h" 35#include "llvm/LLVMContext.h" 36#include "llvm/Analysis/ConstantFolding.h" 37#include "llvm/Analysis/LoopInfo.h" 38#include "llvm/Analysis/LoopPass.h" 39#include "llvm/Analysis/Dominators.h" 40#include "llvm/Transforms/Utils/Cloning.h" 41#include "llvm/Transforms/Utils/Local.h" 42#include "llvm/Transforms/Utils/BasicBlockUtils.h" 43#include "llvm/ADT/Statistic.h" 44#include "llvm/ADT/SmallPtrSet.h" 45#include "llvm/ADT/STLExtras.h" 46#include "llvm/Support/CommandLine.h" 47#include "llvm/Support/Debug.h" 48#include "llvm/Support/raw_ostream.h" 49#include <algorithm> 50#include <set> 51using namespace llvm; 52 53STATISTIC(NumBranches, "Number of branches unswitched"); 54STATISTIC(NumSwitches, "Number of switches unswitched"); 55STATISTIC(NumSelects , "Number of selects unswitched"); 56STATISTIC(NumTrivial , "Number of unswitches that are trivial"); 57STATISTIC(NumSimplify, "Number of simplifications of unswitched code"); 58 59static cl::opt<unsigned> 60Threshold("loop-unswitch-threshold", cl::desc("Max loop size to unswitch"), 61 cl::init(10), cl::Hidden); 62 63namespace { 64 class LoopUnswitch : public LoopPass { 65 LoopInfo *LI; // Loop information 66 LPPassManager *LPM; 67 68 // LoopProcessWorklist - Used to check if second loop needs processing 69 // after RewriteLoopBodyWithConditionConstant rewrites first loop. 70 std::vector<Loop*> LoopProcessWorklist; 71 SmallPtrSet<Value *,8> UnswitchedVals; 72 73 bool OptimizeForSize; 74 bool redoLoop; 75 76 Loop *currentLoop; 77 DominanceFrontier *DF; 78 DominatorTree *DT; 79 BasicBlock *loopHeader; 80 BasicBlock *loopPreheader; 81 82 // LoopBlocks contains all of the basic blocks of the loop, including the 83 // preheader of the loop, the body of the loop, and the exit blocks of the 84 // loop, in that order. 85 std::vector<BasicBlock*> LoopBlocks; 86 // NewBlocks contained cloned copy of basic blocks from LoopBlocks. 87 std::vector<BasicBlock*> NewBlocks; 88 89 public: 90 static char ID; // Pass ID, replacement for typeid 91 explicit LoopUnswitch(bool Os = false) : 92 LoopPass(&ID), OptimizeForSize(Os), redoLoop(false), 93 currentLoop(NULL), DF(NULL), DT(NULL), loopHeader(NULL), 94 loopPreheader(NULL) {} 95 96 bool runOnLoop(Loop *L, LPPassManager &LPM); 97 bool processCurrentLoop(); 98 99 /// This transformation requires natural loop information & requires that 100 /// loop preheaders be inserted into the CFG... 101 /// 102 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 103 AU.addRequiredID(LoopSimplifyID); 104 AU.addPreservedID(LoopSimplifyID); 105 AU.addRequired<LoopInfo>(); 106 AU.addPreserved<LoopInfo>(); 107 AU.addRequiredID(LCSSAID); 108 AU.addPreservedID(LCSSAID); 109 AU.addPreserved<DominatorTree>(); 110 AU.addPreserved<DominanceFrontier>(); 111 } 112 113 private: 114 115 /// RemoveLoopFromWorklist - If the specified loop is on the loop worklist, 116 /// remove it. 117 void RemoveLoopFromWorklist(Loop *L) { 118 std::vector<Loop*>::iterator I = std::find(LoopProcessWorklist.begin(), 119 LoopProcessWorklist.end(), L); 120 if (I != LoopProcessWorklist.end()) 121 LoopProcessWorklist.erase(I); 122 } 123 124 void initLoopData() { 125 loopHeader = currentLoop->getHeader(); 126 loopPreheader = currentLoop->getLoopPreheader(); 127 } 128 129 /// Split all of the edges from inside the loop to their exit blocks. 130 /// Update the appropriate Phi nodes as we do so. 131 void SplitExitEdges(Loop *L, const SmallVector<BasicBlock *, 8> &ExitBlocks); 132 133 bool UnswitchIfProfitable(Value *LoopCond, Constant *Val); 134 unsigned getLoopUnswitchCost(Value *LIC); 135 void UnswitchTrivialCondition(Loop *L, Value *Cond, Constant *Val, 136 BasicBlock *ExitBlock); 137 void UnswitchNontrivialCondition(Value *LIC, Constant *OnVal, Loop *L); 138 139 void RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, 140 Constant *Val, bool isEqual); 141 142 void EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val, 143 BasicBlock *TrueDest, 144 BasicBlock *FalseDest, 145 Instruction *InsertPt); 146 147 void SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L); 148 void RemoveBlockIfDead(BasicBlock *BB, 149 std::vector<Instruction*> &Worklist, Loop *l); 150 void RemoveLoopFromHierarchy(Loop *L); 151 bool IsTrivialUnswitchCondition(Value *Cond, Constant **Val = 0, 152 BasicBlock **LoopExit = 0); 153 154 }; 155} 156char LoopUnswitch::ID = 0; 157static RegisterPass<LoopUnswitch> X("loop-unswitch", "Unswitch loops"); 158 159Pass *llvm::createLoopUnswitchPass(bool Os) { 160 return new LoopUnswitch(Os); 161} 162 163/// FindLIVLoopCondition - Cond is a condition that occurs in L. If it is 164/// invariant in the loop, or has an invariant piece, return the invariant. 165/// Otherwise, return null. 166static Value *FindLIVLoopCondition(Value *Cond, Loop *L, bool &Changed) { 167 // Constants should be folded, not unswitched on! 168 if (isa<Constant>(Cond)) return 0; 169 170 // TODO: Handle: br (VARIANT|INVARIANT). 171 172 // Hoist simple values out. 173 if (L->makeLoopInvariant(Cond, Changed)) 174 return Cond; 175 176 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Cond)) 177 if (BO->getOpcode() == Instruction::And || 178 BO->getOpcode() == Instruction::Or) { 179 // If either the left or right side is invariant, we can unswitch on this, 180 // which will cause the branch to go away in one loop and the condition to 181 // simplify in the other one. 182 if (Value *LHS = FindLIVLoopCondition(BO->getOperand(0), L, Changed)) 183 return LHS; 184 if (Value *RHS = FindLIVLoopCondition(BO->getOperand(1), L, Changed)) 185 return RHS; 186 } 187 188 return 0; 189} 190 191bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) { 192 LI = &getAnalysis<LoopInfo>(); 193 LPM = &LPM_Ref; 194 DF = getAnalysisIfAvailable<DominanceFrontier>(); 195 DT = getAnalysisIfAvailable<DominatorTree>(); 196 currentLoop = L; 197 Function *F = currentLoop->getHeader()->getParent(); 198 bool Changed = false; 199 do { 200 assert(currentLoop->isLCSSAForm()); 201 redoLoop = false; 202 Changed |= processCurrentLoop(); 203 } while(redoLoop); 204 205 if (Changed) { 206 // FIXME: Reconstruct dom info, because it is not preserved properly. 207 if (DT) 208 DT->runOnFunction(*F); 209 if (DF) 210 DF->runOnFunction(*F); 211 } 212 return Changed; 213} 214 215/// processCurrentLoop - Do actual work and unswitch loop if possible 216/// and profitable. 217bool LoopUnswitch::processCurrentLoop() { 218 bool Changed = false; 219 LLVMContext &Context = currentLoop->getHeader()->getContext(); 220 221 // Loop over all of the basic blocks in the loop. If we find an interior 222 // block that is branching on a loop-invariant condition, we can unswitch this 223 // loop. 224 for (Loop::block_iterator I = currentLoop->block_begin(), 225 E = currentLoop->block_end(); 226 I != E; ++I) { 227 TerminatorInst *TI = (*I)->getTerminator(); 228 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { 229 // If this isn't branching on an invariant condition, we can't unswitch 230 // it. 231 if (BI->isConditional()) { 232 // See if this, or some part of it, is loop invariant. If so, we can 233 // unswitch on it if we desire. 234 Value *LoopCond = FindLIVLoopCondition(BI->getCondition(), 235 currentLoop, Changed); 236 if (LoopCond && UnswitchIfProfitable(LoopCond, 237 ConstantInt::getTrue(Context))) { 238 ++NumBranches; 239 return true; 240 } 241 } 242 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { 243 Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), 244 currentLoop, Changed); 245 if (LoopCond && SI->getNumCases() > 1) { 246 // Find a value to unswitch on: 247 // FIXME: this should chose the most expensive case! 248 Constant *UnswitchVal = SI->getCaseValue(1); 249 // Do not process same value again and again. 250 if (!UnswitchedVals.insert(UnswitchVal)) 251 continue; 252 253 if (UnswitchIfProfitable(LoopCond, UnswitchVal)) { 254 ++NumSwitches; 255 return true; 256 } 257 } 258 } 259 260 // Scan the instructions to check for unswitchable values. 261 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end(); 262 BBI != E; ++BBI) 263 if (SelectInst *SI = dyn_cast<SelectInst>(BBI)) { 264 Value *LoopCond = FindLIVLoopCondition(SI->getCondition(), 265 currentLoop, Changed); 266 if (LoopCond && UnswitchIfProfitable(LoopCond, 267 ConstantInt::getTrue(Context))) { 268 ++NumSelects; 269 return true; 270 } 271 } 272 } 273 return Changed; 274} 275 276/// isTrivialLoopExitBlock - Check to see if all paths from BB either: 277/// 1. Exit the loop with no side effects. 278/// 2. Branch to the latch block with no side-effects. 279/// 280/// If these conditions are true, we return true and set ExitBB to the block we 281/// exit through. 282/// 283static bool isTrivialLoopExitBlockHelper(Loop *L, BasicBlock *BB, 284 BasicBlock *&ExitBB, 285 std::set<BasicBlock*> &Visited) { 286 if (!Visited.insert(BB).second) { 287 // Already visited and Ok, end of recursion. 288 return true; 289 } else if (!L->contains(BB)) { 290 // Otherwise, this is a loop exit, this is fine so long as this is the 291 // first exit. 292 if (ExitBB != 0) return false; 293 ExitBB = BB; 294 return true; 295 } 296 297 // Otherwise, this is an unvisited intra-loop node. Check all successors. 298 for (succ_iterator SI = succ_begin(BB), E = succ_end(BB); SI != E; ++SI) { 299 // Check to see if the successor is a trivial loop exit. 300 if (!isTrivialLoopExitBlockHelper(L, *SI, ExitBB, Visited)) 301 return false; 302 } 303 304 // Okay, everything after this looks good, check to make sure that this block 305 // doesn't include any side effects. 306 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) 307 if (I->mayHaveSideEffects()) 308 return false; 309 310 return true; 311} 312 313/// isTrivialLoopExitBlock - Return true if the specified block unconditionally 314/// leads to an exit from the specified loop, and has no side-effects in the 315/// process. If so, return the block that is exited to, otherwise return null. 316static BasicBlock *isTrivialLoopExitBlock(Loop *L, BasicBlock *BB) { 317 std::set<BasicBlock*> Visited; 318 Visited.insert(L->getHeader()); // Branches to header are ok. 319 BasicBlock *ExitBB = 0; 320 if (isTrivialLoopExitBlockHelper(L, BB, ExitBB, Visited)) 321 return ExitBB; 322 return 0; 323} 324 325/// IsTrivialUnswitchCondition - Check to see if this unswitch condition is 326/// trivial: that is, that the condition controls whether or not the loop does 327/// anything at all. If this is a trivial condition, unswitching produces no 328/// code duplications (equivalently, it produces a simpler loop and a new empty 329/// loop, which gets deleted). 330/// 331/// If this is a trivial condition, return true, otherwise return false. When 332/// returning true, this sets Cond and Val to the condition that controls the 333/// trivial condition: when Cond dynamically equals Val, the loop is known to 334/// exit. Finally, this sets LoopExit to the BB that the loop exits to when 335/// Cond == Val. 336/// 337bool LoopUnswitch::IsTrivialUnswitchCondition(Value *Cond, Constant **Val, 338 BasicBlock **LoopExit) { 339 BasicBlock *Header = currentLoop->getHeader(); 340 TerminatorInst *HeaderTerm = Header->getTerminator(); 341 LLVMContext &Context = Header->getContext(); 342 343 BasicBlock *LoopExitBB = 0; 344 if (BranchInst *BI = dyn_cast<BranchInst>(HeaderTerm)) { 345 // If the header block doesn't end with a conditional branch on Cond, we 346 // can't handle it. 347 if (!BI->isConditional() || BI->getCondition() != Cond) 348 return false; 349 350 // Check to see if a successor of the branch is guaranteed to go to the 351 // latch block or exit through a one exit block without having any 352 // side-effects. If so, determine the value of Cond that causes it to do 353 // this. 354 if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, 355 BI->getSuccessor(0)))) { 356 if (Val) *Val = ConstantInt::getTrue(Context); 357 } else if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, 358 BI->getSuccessor(1)))) { 359 if (Val) *Val = ConstantInt::getFalse(Context); 360 } 361 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(HeaderTerm)) { 362 // If this isn't a switch on Cond, we can't handle it. 363 if (SI->getCondition() != Cond) return false; 364 365 // Check to see if a successor of the switch is guaranteed to go to the 366 // latch block or exit through a one exit block without having any 367 // side-effects. If so, determine the value of Cond that causes it to do 368 // this. Note that we can't trivially unswitch on the default case. 369 for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) 370 if ((LoopExitBB = isTrivialLoopExitBlock(currentLoop, 371 SI->getSuccessor(i)))) { 372 // Okay, we found a trivial case, remember the value that is trivial. 373 if (Val) *Val = SI->getCaseValue(i); 374 break; 375 } 376 } 377 378 // If we didn't find a single unique LoopExit block, or if the loop exit block 379 // contains phi nodes, this isn't trivial. 380 if (!LoopExitBB || isa<PHINode>(LoopExitBB->begin())) 381 return false; // Can't handle this. 382 383 if (LoopExit) *LoopExit = LoopExitBB; 384 385 // We already know that nothing uses any scalar values defined inside of this 386 // loop. As such, we just have to check to see if this loop will execute any 387 // side-effecting instructions (e.g. stores, calls, volatile loads) in the 388 // part of the loop that the code *would* execute. We already checked the 389 // tail, check the header now. 390 for (BasicBlock::iterator I = Header->begin(), E = Header->end(); I != E; ++I) 391 if (I->mayHaveSideEffects()) 392 return false; 393 return true; 394} 395 396/// getLoopUnswitchCost - Return the cost (code size growth) that will happen if 397/// we choose to unswitch current loop on the specified value. 398/// 399unsigned LoopUnswitch::getLoopUnswitchCost(Value *LIC) { 400 // If the condition is trivial, always unswitch. There is no code growth for 401 // this case. 402 if (IsTrivialUnswitchCondition(LIC)) 403 return 0; 404 405 // FIXME: This is really overly conservative. However, more liberal 406 // estimations have thus far resulted in excessive unswitching, which is bad 407 // both in compile time and in code size. This should be replaced once 408 // someone figures out how a good estimation. 409 return currentLoop->getBlocks().size(); 410 411 unsigned Cost = 0; 412 // FIXME: this is brain dead. It should take into consideration code 413 // shrinkage. 414 for (Loop::block_iterator I = currentLoop->block_begin(), 415 E = currentLoop->block_end(); 416 I != E; ++I) { 417 BasicBlock *BB = *I; 418 // Do not include empty blocks in the cost calculation. This happen due to 419 // loop canonicalization and will be removed. 420 if (BB->begin() == BasicBlock::iterator(BB->getTerminator())) 421 continue; 422 423 // Count basic blocks. 424 ++Cost; 425 } 426 427 return Cost; 428} 429 430/// UnswitchIfProfitable - We have found that we can unswitch currentLoop when 431/// LoopCond == Val to simplify the loop. If we decide that this is profitable, 432/// unswitch the loop, reprocess the pieces, then return true. 433bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val){ 434 435 initLoopData(); 436 Function *F = loopHeader->getParent(); 437 438 439 // Check to see if it would be profitable to unswitch current loop. 440 unsigned Cost = getLoopUnswitchCost(LoopCond); 441 442 // Do not do non-trivial unswitch while optimizing for size. 443 if (Cost && OptimizeForSize) 444 return false; 445 if (Cost && !F->isDeclaration() && F->hasFnAttr(Attribute::OptimizeForSize)) 446 return false; 447 448 if (Cost > Threshold) { 449 // FIXME: this should estimate growth by the amount of code shared by the 450 // resultant unswitched loops. 451 // 452 DEBUG(errs() << "NOT unswitching loop %" 453 << currentLoop->getHeader()->getName() << ", cost too high: " 454 << currentLoop->getBlocks().size() << "\n"); 455 return false; 456 } 457 458 Constant *CondVal; 459 BasicBlock *ExitBlock; 460 if (IsTrivialUnswitchCondition(LoopCond, &CondVal, &ExitBlock)) { 461 UnswitchTrivialCondition(currentLoop, LoopCond, CondVal, ExitBlock); 462 } else { 463 UnswitchNontrivialCondition(LoopCond, Val, currentLoop); 464 } 465 466 return true; 467} 468 469// RemapInstruction - Convert the instruction operands from referencing the 470// current values into those specified by ValueMap. 471// 472static inline void RemapInstruction(Instruction *I, 473 DenseMap<const Value *, Value*> &ValueMap) { 474 for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) { 475 Value *Op = I->getOperand(op); 476 DenseMap<const Value *, Value*>::iterator It = ValueMap.find(Op); 477 if (It != ValueMap.end()) Op = It->second; 478 I->setOperand(op, Op); 479 } 480} 481 482/// CloneLoop - Recursively clone the specified loop and all of its children, 483/// mapping the blocks with the specified map. 484static Loop *CloneLoop(Loop *L, Loop *PL, DenseMap<const Value*, Value*> &VM, 485 LoopInfo *LI, LPPassManager *LPM) { 486 Loop *New = new Loop(); 487 488 LPM->insertLoop(New, PL); 489 490 // Add all of the blocks in L to the new loop. 491 for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); 492 I != E; ++I) 493 if (LI->getLoopFor(*I) == L) 494 New->addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), LI->getBase()); 495 496 // Add all of the subloops to the new loop. 497 for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) 498 CloneLoop(*I, New, VM, LI, LPM); 499 500 return New; 501} 502 503/// EmitPreheaderBranchOnCondition - Emit a conditional branch on two values 504/// if LIC == Val, branch to TrueDst, otherwise branch to FalseDest. Insert the 505/// code immediately before InsertPt. 506void LoopUnswitch::EmitPreheaderBranchOnCondition(Value *LIC, Constant *Val, 507 BasicBlock *TrueDest, 508 BasicBlock *FalseDest, 509 Instruction *InsertPt) { 510 // Insert a conditional branch on LIC to the two preheaders. The original 511 // code is the true version and the new code is the false version. 512 Value *BranchVal = LIC; 513 if (!isa<ConstantInt>(Val) || 514 Val->getType() != Type::getInt1Ty(LIC->getContext())) 515 BranchVal = new ICmpInst(InsertPt, ICmpInst::ICMP_EQ, LIC, Val, "tmp"); 516 else if (Val != ConstantInt::getTrue(Val->getContext())) 517 // We want to enter the new loop when the condition is true. 518 std::swap(TrueDest, FalseDest); 519 520 // Insert the new branch. 521 BranchInst::Create(TrueDest, FalseDest, BranchVal, InsertPt); 522} 523 524/// UnswitchTrivialCondition - Given a loop that has a trivial unswitchable 525/// condition in it (a cond branch from its header block to its latch block, 526/// where the path through the loop that doesn't execute its body has no 527/// side-effects), unswitch it. This doesn't involve any code duplication, just 528/// moving the conditional branch outside of the loop and updating loop info. 529void LoopUnswitch::UnswitchTrivialCondition(Loop *L, Value *Cond, 530 Constant *Val, 531 BasicBlock *ExitBlock) { 532 DEBUG(errs() << "loop-unswitch: Trivial-Unswitch loop %" 533 << loopHeader->getName() << " [" << L->getBlocks().size() 534 << " blocks] in Function " << L->getHeader()->getParent()->getName() 535 << " on cond: " << *Val << " == " << *Cond << "\n"); 536 537 // First step, split the preheader, so that we know that there is a safe place 538 // to insert the conditional branch. We will change loopPreheader to have a 539 // conditional branch on Cond. 540 BasicBlock *NewPH = SplitEdge(loopPreheader, loopHeader, this); 541 542 // Now that we have a place to insert the conditional branch, create a place 543 // to branch to: this is the exit block out of the loop that we should 544 // short-circuit to. 545 546 // Split this block now, so that the loop maintains its exit block, and so 547 // that the jump from the preheader can execute the contents of the exit block 548 // without actually branching to it (the exit block should be dominated by the 549 // loop header, not the preheader). 550 assert(!L->contains(ExitBlock) && "Exit block is in the loop?"); 551 BasicBlock *NewExit = SplitBlock(ExitBlock, ExitBlock->begin(), this); 552 553 // Okay, now we have a position to branch from and a position to branch to, 554 // insert the new conditional branch. 555 EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH, 556 loopPreheader->getTerminator()); 557 LPM->deleteSimpleAnalysisValue(loopPreheader->getTerminator(), L); 558 loopPreheader->getTerminator()->eraseFromParent(); 559 560 // We need to reprocess this loop, it could be unswitched again. 561 redoLoop = true; 562 563 // Now that we know that the loop is never entered when this condition is a 564 // particular value, rewrite the loop with this info. We know that this will 565 // at least eliminate the old branch. 566 RewriteLoopBodyWithConditionConstant(L, Cond, Val, false); 567 ++NumTrivial; 568} 569 570/// SplitExitEdges - Split all of the edges from inside the loop to their exit 571/// blocks. Update the appropriate Phi nodes as we do so. 572void LoopUnswitch::SplitExitEdges(Loop *L, 573 const SmallVector<BasicBlock *, 8> &ExitBlocks) 574{ 575 576 for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { 577 BasicBlock *ExitBlock = ExitBlocks[i]; 578 std::vector<BasicBlock*> Preds(pred_begin(ExitBlock), pred_end(ExitBlock)); 579 580 for (unsigned j = 0, e = Preds.size(); j != e; ++j) { 581 BasicBlock* NewExitBlock = SplitEdge(Preds[j], ExitBlock, this); 582 BasicBlock* StartBlock = Preds[j]; 583 BasicBlock* EndBlock; 584 if (NewExitBlock->getSinglePredecessor() == ExitBlock) { 585 EndBlock = NewExitBlock; 586 NewExitBlock = EndBlock->getSinglePredecessor(); 587 } else { 588 EndBlock = ExitBlock; 589 } 590 591 std::set<PHINode*> InsertedPHIs; 592 PHINode* OldLCSSA = 0; 593 for (BasicBlock::iterator I = EndBlock->begin(); 594 (OldLCSSA = dyn_cast<PHINode>(I)); ++I) { 595 Value* OldValue = OldLCSSA->getIncomingValueForBlock(NewExitBlock); 596 PHINode* NewLCSSA = PHINode::Create(OldLCSSA->getType(), 597 OldLCSSA->getName() + ".us-lcssa", 598 NewExitBlock->getTerminator()); 599 NewLCSSA->addIncoming(OldValue, StartBlock); 600 OldLCSSA->setIncomingValue(OldLCSSA->getBasicBlockIndex(NewExitBlock), 601 NewLCSSA); 602 InsertedPHIs.insert(NewLCSSA); 603 } 604 605 BasicBlock::iterator InsertPt = EndBlock->getFirstNonPHI(); 606 for (BasicBlock::iterator I = NewExitBlock->begin(); 607 (OldLCSSA = dyn_cast<PHINode>(I)) && InsertedPHIs.count(OldLCSSA) == 0; 608 ++I) { 609 PHINode *NewLCSSA = PHINode::Create(OldLCSSA->getType(), 610 OldLCSSA->getName() + ".us-lcssa", 611 InsertPt); 612 OldLCSSA->replaceAllUsesWith(NewLCSSA); 613 NewLCSSA->addIncoming(OldLCSSA, NewExitBlock); 614 } 615 616 } 617 } 618 619} 620 621/// UnswitchNontrivialCondition - We determined that the loop is profitable 622/// to unswitch when LIC equal Val. Split it into loop versions and test the 623/// condition outside of either loop. Return the loops created as Out1/Out2. 624void LoopUnswitch::UnswitchNontrivialCondition(Value *LIC, Constant *Val, 625 Loop *L) { 626 Function *F = loopHeader->getParent(); 627 DEBUG(errs() << "loop-unswitch: Unswitching loop %" 628 << loopHeader->getName() << " [" << L->getBlocks().size() 629 << " blocks] in Function " << F->getName() 630 << " when '" << *Val << "' == " << *LIC << "\n"); 631 632 LoopBlocks.clear(); 633 NewBlocks.clear(); 634 635 // First step, split the preheader and exit blocks, and add these blocks to 636 // the LoopBlocks list. 637 BasicBlock *NewPreheader = SplitEdge(loopPreheader, loopHeader, this); 638 LoopBlocks.push_back(NewPreheader); 639 640 // We want the loop to come after the preheader, but before the exit blocks. 641 LoopBlocks.insert(LoopBlocks.end(), L->block_begin(), L->block_end()); 642 643 SmallVector<BasicBlock*, 8> ExitBlocks; 644 L->getUniqueExitBlocks(ExitBlocks); 645 646 // Split all of the edges from inside the loop to their exit blocks. Update 647 // the appropriate Phi nodes as we do so. 648 SplitExitEdges(L, ExitBlocks); 649 650 // The exit blocks may have been changed due to edge splitting, recompute. 651 ExitBlocks.clear(); 652 L->getUniqueExitBlocks(ExitBlocks); 653 654 // Add exit blocks to the loop blocks. 655 LoopBlocks.insert(LoopBlocks.end(), ExitBlocks.begin(), ExitBlocks.end()); 656 657 // Next step, clone all of the basic blocks that make up the loop (including 658 // the loop preheader and exit blocks), keeping track of the mapping between 659 // the instructions and blocks. 660 NewBlocks.reserve(LoopBlocks.size()); 661 DenseMap<const Value*, Value*> ValueMap; 662 for (unsigned i = 0, e = LoopBlocks.size(); i != e; ++i) { 663 BasicBlock *New = CloneBasicBlock(LoopBlocks[i], ValueMap, ".us", F); 664 NewBlocks.push_back(New); 665 ValueMap[LoopBlocks[i]] = New; // Keep the BB mapping. 666 LPM->cloneBasicBlockSimpleAnalysis(LoopBlocks[i], New, L); 667 } 668 669 // Splice the newly inserted blocks into the function right before the 670 // original preheader. 671 F->getBasicBlockList().splice(LoopBlocks[0], F->getBasicBlockList(), 672 NewBlocks[0], F->end()); 673 674 // Now we create the new Loop object for the versioned loop. 675 Loop *NewLoop = CloneLoop(L, L->getParentLoop(), ValueMap, LI, LPM); 676 Loop *ParentLoop = L->getParentLoop(); 677 if (ParentLoop) { 678 // Make sure to add the cloned preheader and exit blocks to the parent loop 679 // as well. 680 ParentLoop->addBasicBlockToLoop(NewBlocks[0], LI->getBase()); 681 } 682 683 for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) { 684 BasicBlock *NewExit = cast<BasicBlock>(ValueMap[ExitBlocks[i]]); 685 // The new exit block should be in the same loop as the old one. 686 if (Loop *ExitBBLoop = LI->getLoopFor(ExitBlocks[i])) 687 ExitBBLoop->addBasicBlockToLoop(NewExit, LI->getBase()); 688 689 assert(NewExit->getTerminator()->getNumSuccessors() == 1 && 690 "Exit block should have been split to have one successor!"); 691 BasicBlock *ExitSucc = NewExit->getTerminator()->getSuccessor(0); 692 693 // If the successor of the exit block had PHI nodes, add an entry for 694 // NewExit. 695 PHINode *PN; 696 for (BasicBlock::iterator I = ExitSucc->begin(); 697 (PN = dyn_cast<PHINode>(I)); ++I) { 698 Value *V = PN->getIncomingValueForBlock(ExitBlocks[i]); 699 DenseMap<const Value *, Value*>::iterator It = ValueMap.find(V); 700 if (It != ValueMap.end()) V = It->second; 701 PN->addIncoming(V, NewExit); 702 } 703 } 704 705 // Rewrite the code to refer to itself. 706 for (unsigned i = 0, e = NewBlocks.size(); i != e; ++i) 707 for (BasicBlock::iterator I = NewBlocks[i]->begin(), 708 E = NewBlocks[i]->end(); I != E; ++I) 709 RemapInstruction(I, ValueMap); 710 711 // Rewrite the original preheader to select between versions of the loop. 712 BranchInst *OldBR = cast<BranchInst>(loopPreheader->getTerminator()); 713 assert(OldBR->isUnconditional() && OldBR->getSuccessor(0) == LoopBlocks[0] && 714 "Preheader splitting did not work correctly!"); 715 716 // Emit the new branch that selects between the two versions of this loop. 717 EmitPreheaderBranchOnCondition(LIC, Val, NewBlocks[0], LoopBlocks[0], OldBR); 718 LPM->deleteSimpleAnalysisValue(OldBR, L); 719 OldBR->eraseFromParent(); 720 721 LoopProcessWorklist.push_back(NewLoop); 722 redoLoop = true; 723 724 // Now we rewrite the original code to know that the condition is true and the 725 // new code to know that the condition is false. 726 RewriteLoopBodyWithConditionConstant(L , LIC, Val, false); 727 728 // It's possible that simplifying one loop could cause the other to be 729 // deleted. If so, don't simplify it. 730 if (!LoopProcessWorklist.empty() && LoopProcessWorklist.back() == NewLoop) 731 RewriteLoopBodyWithConditionConstant(NewLoop, LIC, Val, true); 732 733} 734 735/// RemoveFromWorklist - Remove all instances of I from the worklist vector 736/// specified. 737static void RemoveFromWorklist(Instruction *I, 738 std::vector<Instruction*> &Worklist) { 739 std::vector<Instruction*>::iterator WI = std::find(Worklist.begin(), 740 Worklist.end(), I); 741 while (WI != Worklist.end()) { 742 unsigned Offset = WI-Worklist.begin(); 743 Worklist.erase(WI); 744 WI = std::find(Worklist.begin()+Offset, Worklist.end(), I); 745 } 746} 747 748/// ReplaceUsesOfWith - When we find that I really equals V, remove I from the 749/// program, replacing all uses with V and update the worklist. 750static void ReplaceUsesOfWith(Instruction *I, Value *V, 751 std::vector<Instruction*> &Worklist, 752 Loop *L, LPPassManager *LPM) { 753 DEBUG(errs() << "Replace with '" << *V << "': " << *I); 754 755 // Add uses to the worklist, which may be dead now. 756 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 757 if (Instruction *Use = dyn_cast<Instruction>(I->getOperand(i))) 758 Worklist.push_back(Use); 759 760 // Add users to the worklist which may be simplified now. 761 for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); 762 UI != E; ++UI) 763 Worklist.push_back(cast<Instruction>(*UI)); 764 LPM->deleteSimpleAnalysisValue(I, L); 765 RemoveFromWorklist(I, Worklist); 766 I->replaceAllUsesWith(V); 767 I->eraseFromParent(); 768 ++NumSimplify; 769} 770 771/// RemoveBlockIfDead - If the specified block is dead, remove it, update loop 772/// information, and remove any dead successors it has. 773/// 774void LoopUnswitch::RemoveBlockIfDead(BasicBlock *BB, 775 std::vector<Instruction*> &Worklist, 776 Loop *L) { 777 if (pred_begin(BB) != pred_end(BB)) { 778 // This block isn't dead, since an edge to BB was just removed, see if there 779 // are any easy simplifications we can do now. 780 if (BasicBlock *Pred = BB->getSinglePredecessor()) { 781 // If it has one pred, fold phi nodes in BB. 782 while (isa<PHINode>(BB->begin())) 783 ReplaceUsesOfWith(BB->begin(), 784 cast<PHINode>(BB->begin())->getIncomingValue(0), 785 Worklist, L, LPM); 786 787 // If this is the header of a loop and the only pred is the latch, we now 788 // have an unreachable loop. 789 if (Loop *L = LI->getLoopFor(BB)) 790 if (loopHeader == BB && L->contains(Pred)) { 791 // Remove the branch from the latch to the header block, this makes 792 // the header dead, which will make the latch dead (because the header 793 // dominates the latch). 794 LPM->deleteSimpleAnalysisValue(Pred->getTerminator(), L); 795 Pred->getTerminator()->eraseFromParent(); 796 new UnreachableInst(BB->getContext(), Pred); 797 798 // The loop is now broken, remove it from LI. 799 RemoveLoopFromHierarchy(L); 800 801 // Reprocess the header, which now IS dead. 802 RemoveBlockIfDead(BB, Worklist, L); 803 return; 804 } 805 806 // If pred ends in a uncond branch, add uncond branch to worklist so that 807 // the two blocks will get merged. 808 if (BranchInst *BI = dyn_cast<BranchInst>(Pred->getTerminator())) 809 if (BI->isUnconditional()) 810 Worklist.push_back(BI); 811 } 812 return; 813 } 814 815 DEBUG(errs() << "Nuking dead block: " << *BB); 816 817 // Remove the instructions in the basic block from the worklist. 818 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 819 RemoveFromWorklist(I, Worklist); 820 821 // Anything that uses the instructions in this basic block should have their 822 // uses replaced with undefs. 823 if (!I->use_empty()) 824 I->replaceAllUsesWith(UndefValue::get(I->getType())); 825 } 826 827 // If this is the edge to the header block for a loop, remove the loop and 828 // promote all subloops. 829 if (Loop *BBLoop = LI->getLoopFor(BB)) { 830 if (BBLoop->getLoopLatch() == BB) 831 RemoveLoopFromHierarchy(BBLoop); 832 } 833 834 // Remove the block from the loop info, which removes it from any loops it 835 // was in. 836 LI->removeBlock(BB); 837 838 839 // Remove phi node entries in successors for this block. 840 TerminatorInst *TI = BB->getTerminator(); 841 SmallVector<BasicBlock*, 4> Succs; 842 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) { 843 Succs.push_back(TI->getSuccessor(i)); 844 TI->getSuccessor(i)->removePredecessor(BB); 845 } 846 847 // Unique the successors, remove anything with multiple uses. 848 array_pod_sort(Succs.begin(), Succs.end()); 849 Succs.erase(std::unique(Succs.begin(), Succs.end()), Succs.end()); 850 851 // Remove the basic block, including all of the instructions contained in it. 852 LPM->deleteSimpleAnalysisValue(BB, L); 853 BB->eraseFromParent(); 854 // Remove successor blocks here that are not dead, so that we know we only 855 // have dead blocks in this list. Nondead blocks have a way of becoming dead, 856 // then getting removed before we revisit them, which is badness. 857 // 858 for (unsigned i = 0; i != Succs.size(); ++i) 859 if (pred_begin(Succs[i]) != pred_end(Succs[i])) { 860 // One exception is loop headers. If this block was the preheader for a 861 // loop, then we DO want to visit the loop so the loop gets deleted. 862 // We know that if the successor is a loop header, that this loop had to 863 // be the preheader: the case where this was the latch block was handled 864 // above and headers can only have two predecessors. 865 if (!LI->isLoopHeader(Succs[i])) { 866 Succs.erase(Succs.begin()+i); 867 --i; 868 } 869 } 870 871 for (unsigned i = 0, e = Succs.size(); i != e; ++i) 872 RemoveBlockIfDead(Succs[i], Worklist, L); 873} 874 875/// RemoveLoopFromHierarchy - We have discovered that the specified loop has 876/// become unwrapped, either because the backedge was deleted, or because the 877/// edge into the header was removed. If the edge into the header from the 878/// latch block was removed, the loop is unwrapped but subloops are still alive, 879/// so they just reparent loops. If the loops are actually dead, they will be 880/// removed later. 881void LoopUnswitch::RemoveLoopFromHierarchy(Loop *L) { 882 LPM->deleteLoopFromQueue(L); 883 RemoveLoopFromWorklist(L); 884} 885 886// RewriteLoopBodyWithConditionConstant - We know either that the value LIC has 887// the value specified by Val in the specified loop, or we know it does NOT have 888// that value. Rewrite any uses of LIC or of properties correlated to it. 889void LoopUnswitch::RewriteLoopBodyWithConditionConstant(Loop *L, Value *LIC, 890 Constant *Val, 891 bool IsEqual) { 892 assert(!isa<Constant>(LIC) && "Why are we unswitching on a constant?"); 893 894 // FIXME: Support correlated properties, like: 895 // for (...) 896 // if (li1 < li2) 897 // ... 898 // if (li1 > li2) 899 // ... 900 901 // FOLD boolean conditions (X|LIC), (X&LIC). Fold conditional branches, 902 // selects, switches. 903 std::vector<User*> Users(LIC->use_begin(), LIC->use_end()); 904 std::vector<Instruction*> Worklist; 905 LLVMContext &Context = Val->getContext(); 906 907 908 // If we know that LIC == Val, or that LIC == NotVal, just replace uses of LIC 909 // in the loop with the appropriate one directly. 910 if (IsEqual || (isa<ConstantInt>(Val) && 911 Val->getType() == Type::getInt1Ty(Val->getContext()))) { 912 Value *Replacement; 913 if (IsEqual) 914 Replacement = Val; 915 else 916 Replacement = ConstantInt::get(Type::getInt1Ty(Val->getContext()), 917 !cast<ConstantInt>(Val)->getZExtValue()); 918 919 for (unsigned i = 0, e = Users.size(); i != e; ++i) 920 if (Instruction *U = cast<Instruction>(Users[i])) { 921 if (!L->contains(U->getParent())) 922 continue; 923 U->replaceUsesOfWith(LIC, Replacement); 924 Worklist.push_back(U); 925 } 926 } else { 927 // Otherwise, we don't know the precise value of LIC, but we do know that it 928 // is certainly NOT "Val". As such, simplify any uses in the loop that we 929 // can. This case occurs when we unswitch switch statements. 930 for (unsigned i = 0, e = Users.size(); i != e; ++i) 931 if (Instruction *U = cast<Instruction>(Users[i])) { 932 if (!L->contains(U->getParent())) 933 continue; 934 935 Worklist.push_back(U); 936 937 // If we know that LIC is not Val, use this info to simplify code. 938 if (SwitchInst *SI = dyn_cast<SwitchInst>(U)) { 939 for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) { 940 if (SI->getCaseValue(i) == Val) { 941 // Found a dead case value. Don't remove PHI nodes in the 942 // successor if they become single-entry, those PHI nodes may 943 // be in the Users list. 944 945 // FIXME: This is a hack. We need to keep the successor around 946 // and hooked up so as to preserve the loop structure, because 947 // trying to update it is complicated. So instead we preserve the 948 // loop structure and put the block on an dead code path. 949 950 BasicBlock *SISucc = SI->getSuccessor(i); 951 BasicBlock* Old = SI->getParent(); 952 BasicBlock* Split = SplitBlock(Old, SI, this); 953 954 Instruction* OldTerm = Old->getTerminator(); 955 BranchInst::Create(Split, SISucc, 956 ConstantInt::getTrue(Context), OldTerm); 957 958 LPM->deleteSimpleAnalysisValue(Old->getTerminator(), L); 959 Old->getTerminator()->eraseFromParent(); 960 961 PHINode *PN; 962 for (BasicBlock::iterator II = SISucc->begin(); 963 (PN = dyn_cast<PHINode>(II)); ++II) { 964 Value *InVal = PN->removeIncomingValue(Split, false); 965 PN->addIncoming(InVal, Old); 966 } 967 968 SI->removeCase(i); 969 break; 970 } 971 } 972 } 973 974 // TODO: We could do other simplifications, for example, turning 975 // LIC == Val -> false. 976 } 977 } 978 979 SimplifyCode(Worklist, L); 980} 981 982/// SimplifyCode - Okay, now that we have simplified some instructions in the 983/// loop, walk over it and constant prop, dce, and fold control flow where 984/// possible. Note that this is effectively a very simple loop-structure-aware 985/// optimizer. During processing of this loop, L could very well be deleted, so 986/// it must not be used. 987/// 988/// FIXME: When the loop optimizer is more mature, separate this out to a new 989/// pass. 990/// 991void LoopUnswitch::SimplifyCode(std::vector<Instruction*> &Worklist, Loop *L) { 992 while (!Worklist.empty()) { 993 Instruction *I = Worklist.back(); 994 Worklist.pop_back(); 995 996 // Simple constant folding. 997 if (Constant *C = ConstantFoldInstruction(I, I->getContext())) { 998 ReplaceUsesOfWith(I, C, Worklist, L, LPM); 999 continue; 1000 } 1001 1002 // Simple DCE. 1003 if (isInstructionTriviallyDead(I)) { 1004 DEBUG(errs() << "Remove dead instruction '" << *I); 1005 1006 // Add uses to the worklist, which may be dead now. 1007 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 1008 if (Instruction *Use = dyn_cast<Instruction>(I->getOperand(i))) 1009 Worklist.push_back(Use); 1010 LPM->deleteSimpleAnalysisValue(I, L); 1011 RemoveFromWorklist(I, Worklist); 1012 I->eraseFromParent(); 1013 ++NumSimplify; 1014 continue; 1015 } 1016 1017 // Special case hacks that appear commonly in unswitched code. 1018 switch (I->getOpcode()) { 1019 case Instruction::Select: 1020 if (ConstantInt *CB = dyn_cast<ConstantInt>(I->getOperand(0))) { 1021 ReplaceUsesOfWith(I, I->getOperand(!CB->getZExtValue()+1), Worklist, L, 1022 LPM); 1023 continue; 1024 } 1025 break; 1026 case Instruction::And: 1027 if (isa<ConstantInt>(I->getOperand(0)) && 1028 // constant -> RHS 1029 I->getOperand(0)->getType() == Type::getInt1Ty(I->getContext())) 1030 cast<BinaryOperator>(I)->swapOperands(); 1031 if (ConstantInt *CB = dyn_cast<ConstantInt>(I->getOperand(1))) 1032 if (CB->getType() == Type::getInt1Ty(I->getContext())) { 1033 if (CB->isOne()) // X & 1 -> X 1034 ReplaceUsesOfWith(I, I->getOperand(0), Worklist, L, LPM); 1035 else // X & 0 -> 0 1036 ReplaceUsesOfWith(I, I->getOperand(1), Worklist, L, LPM); 1037 continue; 1038 } 1039 break; 1040 case Instruction::Or: 1041 if (isa<ConstantInt>(I->getOperand(0)) && 1042 // constant -> RHS 1043 I->getOperand(0)->getType() == Type::getInt1Ty(I->getContext())) 1044 cast<BinaryOperator>(I)->swapOperands(); 1045 if (ConstantInt *CB = dyn_cast<ConstantInt>(I->getOperand(1))) 1046 if (CB->getType() == Type::getInt1Ty(I->getContext())) { 1047 if (CB->isOne()) // X | 1 -> 1 1048 ReplaceUsesOfWith(I, I->getOperand(1), Worklist, L, LPM); 1049 else // X | 0 -> X 1050 ReplaceUsesOfWith(I, I->getOperand(0), Worklist, L, LPM); 1051 continue; 1052 } 1053 break; 1054 case Instruction::Br: { 1055 BranchInst *BI = cast<BranchInst>(I); 1056 if (BI->isUnconditional()) { 1057 // If BI's parent is the only pred of the successor, fold the two blocks 1058 // together. 1059 BasicBlock *Pred = BI->getParent(); 1060 BasicBlock *Succ = BI->getSuccessor(0); 1061 BasicBlock *SinglePred = Succ->getSinglePredecessor(); 1062 if (!SinglePred) continue; // Nothing to do. 1063 assert(SinglePred == Pred && "CFG broken"); 1064 1065 DEBUG(errs() << "Merging blocks: " << Pred->getName() << " <- " 1066 << Succ->getName() << "\n"); 1067 1068 // Resolve any single entry PHI nodes in Succ. 1069 while (PHINode *PN = dyn_cast<PHINode>(Succ->begin())) 1070 ReplaceUsesOfWith(PN, PN->getIncomingValue(0), Worklist, L, LPM); 1071 1072 // Move all of the successor contents from Succ to Pred. 1073 Pred->getInstList().splice(BI, Succ->getInstList(), Succ->begin(), 1074 Succ->end()); 1075 LPM->deleteSimpleAnalysisValue(BI, L); 1076 BI->eraseFromParent(); 1077 RemoveFromWorklist(BI, Worklist); 1078 1079 // If Succ has any successors with PHI nodes, update them to have 1080 // entries coming from Pred instead of Succ. 1081 Succ->replaceAllUsesWith(Pred); 1082 1083 // Remove Succ from the loop tree. 1084 LI->removeBlock(Succ); 1085 LPM->deleteSimpleAnalysisValue(Succ, L); 1086 Succ->eraseFromParent(); 1087 ++NumSimplify; 1088 } else if (ConstantInt *CB = dyn_cast<ConstantInt>(BI->getCondition())){ 1089 // Conditional branch. Turn it into an unconditional branch, then 1090 // remove dead blocks. 1091 break; // FIXME: Enable. 1092 1093 DEBUG(errs() << "Folded branch: " << *BI); 1094 BasicBlock *DeadSucc = BI->getSuccessor(CB->getZExtValue()); 1095 BasicBlock *LiveSucc = BI->getSuccessor(!CB->getZExtValue()); 1096 DeadSucc->removePredecessor(BI->getParent(), true); 1097 Worklist.push_back(BranchInst::Create(LiveSucc, BI)); 1098 LPM->deleteSimpleAnalysisValue(BI, L); 1099 BI->eraseFromParent(); 1100 RemoveFromWorklist(BI, Worklist); 1101 ++NumSimplify; 1102 1103 RemoveBlockIfDead(DeadSucc, Worklist, L); 1104 } 1105 break; 1106 } 1107 } 1108 } 1109} 1110