BBVectorize.cpp revision 940371bc65570ec0add1ede4f4d9f0a41ba25e09
1//===- BBVectorize.cpp - A Basic-Block Vectorizer -------------------------===// 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 file implements a basic-block vectorization pass. The algorithm was 11// inspired by that used by the Vienna MAP Vectorizor by Franchetti and Kral, 12// et al. It works by looking for chains of pairable operations and then 13// pairing them. 14// 15//===----------------------------------------------------------------------===// 16 17#define BBV_NAME "bb-vectorize" 18#define DEBUG_TYPE BBV_NAME 19#include "llvm/Constants.h" 20#include "llvm/DerivedTypes.h" 21#include "llvm/Function.h" 22#include "llvm/Instructions.h" 23#include "llvm/IntrinsicInst.h" 24#include "llvm/Intrinsics.h" 25#include "llvm/LLVMContext.h" 26#include "llvm/Pass.h" 27#include "llvm/Type.h" 28#include "llvm/ADT/DenseMap.h" 29#include "llvm/ADT/DenseSet.h" 30#include "llvm/ADT/SmallVector.h" 31#include "llvm/ADT/Statistic.h" 32#include "llvm/ADT/STLExtras.h" 33#include "llvm/ADT/StringExtras.h" 34#include "llvm/Analysis/AliasAnalysis.h" 35#include "llvm/Analysis/AliasSetTracker.h" 36#include "llvm/Analysis/ScalarEvolution.h" 37#include "llvm/Analysis/ScalarEvolutionExpressions.h" 38#include "llvm/Analysis/ValueTracking.h" 39#include "llvm/Support/CommandLine.h" 40#include "llvm/Support/Debug.h" 41#include "llvm/Support/raw_ostream.h" 42#include "llvm/Support/ValueHandle.h" 43#include "llvm/Target/TargetData.h" 44#include "llvm/Transforms/Vectorize.h" 45#include <algorithm> 46#include <map> 47using namespace llvm; 48 49static cl::opt<unsigned> 50ReqChainDepth("bb-vectorize-req-chain-depth", cl::init(6), cl::Hidden, 51 cl::desc("The required chain depth for vectorization")); 52 53static cl::opt<unsigned> 54SearchLimit("bb-vectorize-search-limit", cl::init(400), cl::Hidden, 55 cl::desc("The maximum search distance for instruction pairs")); 56 57static cl::opt<bool> 58SplatBreaksChain("bb-vectorize-splat-breaks-chain", cl::init(false), cl::Hidden, 59 cl::desc("Replicating one element to a pair breaks the chain")); 60 61static cl::opt<unsigned> 62VectorBits("bb-vectorize-vector-bits", cl::init(128), cl::Hidden, 63 cl::desc("The size of the native vector registers")); 64 65static cl::opt<unsigned> 66MaxIter("bb-vectorize-max-iter", cl::init(0), cl::Hidden, 67 cl::desc("The maximum number of pairing iterations")); 68 69static cl::opt<unsigned> 70MaxInsts("bb-vectorize-max-instr-per-group", cl::init(500), cl::Hidden, 71 cl::desc("The maximum number of pairable instructions per group")); 72 73static cl::opt<unsigned> 74MaxCandPairsForCycleCheck("bb-vectorize-max-cycle-check-pairs", cl::init(200), 75 cl::Hidden, cl::desc("The maximum number of candidate pairs with which to use" 76 " a full cycle check")); 77 78static cl::opt<bool> 79NoInts("bb-vectorize-no-ints", cl::init(false), cl::Hidden, 80 cl::desc("Don't try to vectorize integer values")); 81 82static cl::opt<bool> 83NoFloats("bb-vectorize-no-floats", cl::init(false), cl::Hidden, 84 cl::desc("Don't try to vectorize floating-point values")); 85 86static cl::opt<bool> 87NoCasts("bb-vectorize-no-casts", cl::init(false), cl::Hidden, 88 cl::desc("Don't try to vectorize casting (conversion) operations")); 89 90static cl::opt<bool> 91NoMath("bb-vectorize-no-math", cl::init(false), cl::Hidden, 92 cl::desc("Don't try to vectorize floating-point math intrinsics")); 93 94static cl::opt<bool> 95NoFMA("bb-vectorize-no-fma", cl::init(false), cl::Hidden, 96 cl::desc("Don't try to vectorize the fused-multiply-add intrinsic")); 97 98static cl::opt<bool> 99NoMemOps("bb-vectorize-no-mem-ops", cl::init(false), cl::Hidden, 100 cl::desc("Don't try to vectorize loads and stores")); 101 102static cl::opt<bool> 103AlignedOnly("bb-vectorize-aligned-only", cl::init(false), cl::Hidden, 104 cl::desc("Only generate aligned loads and stores")); 105 106static cl::opt<bool> 107NoMemOpBoost("bb-vectorize-no-mem-op-boost", 108 cl::init(false), cl::Hidden, 109 cl::desc("Don't boost the chain-depth contribution of loads and stores")); 110 111static cl::opt<bool> 112FastDep("bb-vectorize-fast-dep", cl::init(false), cl::Hidden, 113 cl::desc("Use a fast instruction dependency analysis")); 114 115#ifndef NDEBUG 116static cl::opt<bool> 117DebugInstructionExamination("bb-vectorize-debug-instruction-examination", 118 cl::init(false), cl::Hidden, 119 cl::desc("When debugging is enabled, output information on the" 120 " instruction-examination process")); 121static cl::opt<bool> 122DebugCandidateSelection("bb-vectorize-debug-candidate-selection", 123 cl::init(false), cl::Hidden, 124 cl::desc("When debugging is enabled, output information on the" 125 " candidate-selection process")); 126static cl::opt<bool> 127DebugPairSelection("bb-vectorize-debug-pair-selection", 128 cl::init(false), cl::Hidden, 129 cl::desc("When debugging is enabled, output information on the" 130 " pair-selection process")); 131static cl::opt<bool> 132DebugCycleCheck("bb-vectorize-debug-cycle-check", 133 cl::init(false), cl::Hidden, 134 cl::desc("When debugging is enabled, output information on the" 135 " cycle-checking process")); 136#endif 137 138STATISTIC(NumFusedOps, "Number of operations fused by bb-vectorize"); 139 140namespace { 141 struct BBVectorize : public BasicBlockPass { 142 static char ID; // Pass identification, replacement for typeid 143 144 const VectorizeConfig Config; 145 146 BBVectorize(const VectorizeConfig &C = VectorizeConfig()) 147 : BasicBlockPass(ID), Config(C) { 148 initializeBBVectorizePass(*PassRegistry::getPassRegistry()); 149 } 150 151 BBVectorize(Pass *P, const VectorizeConfig &C) 152 : BasicBlockPass(ID), Config(C) { 153 AA = &P->getAnalysis<AliasAnalysis>(); 154 SE = &P->getAnalysis<ScalarEvolution>(); 155 TD = P->getAnalysisIfAvailable<TargetData>(); 156 } 157 158 typedef std::pair<Value *, Value *> ValuePair; 159 typedef std::pair<ValuePair, size_t> ValuePairWithDepth; 160 typedef std::pair<ValuePair, ValuePair> VPPair; // A ValuePair pair 161 typedef std::pair<std::multimap<Value *, Value *>::iterator, 162 std::multimap<Value *, Value *>::iterator> VPIteratorPair; 163 typedef std::pair<std::multimap<ValuePair, ValuePair>::iterator, 164 std::multimap<ValuePair, ValuePair>::iterator> 165 VPPIteratorPair; 166 167 AliasAnalysis *AA; 168 ScalarEvolution *SE; 169 TargetData *TD; 170 171 // FIXME: const correct? 172 173 bool vectorizePairs(BasicBlock &BB); 174 175 bool getCandidatePairs(BasicBlock &BB, 176 BasicBlock::iterator &Start, 177 std::multimap<Value *, Value *> &CandidatePairs, 178 std::vector<Value *> &PairableInsts); 179 180 void computeConnectedPairs(std::multimap<Value *, Value *> &CandidatePairs, 181 std::vector<Value *> &PairableInsts, 182 std::multimap<ValuePair, ValuePair> &ConnectedPairs); 183 184 void buildDepMap(BasicBlock &BB, 185 std::multimap<Value *, Value *> &CandidatePairs, 186 std::vector<Value *> &PairableInsts, 187 DenseSet<ValuePair> &PairableInstUsers); 188 189 void choosePairs(std::multimap<Value *, Value *> &CandidatePairs, 190 std::vector<Value *> &PairableInsts, 191 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 192 DenseSet<ValuePair> &PairableInstUsers, 193 DenseMap<Value *, Value *>& ChosenPairs); 194 195 void fuseChosenPairs(BasicBlock &BB, 196 std::vector<Value *> &PairableInsts, 197 DenseMap<Value *, Value *>& ChosenPairs); 198 199 bool isInstVectorizable(Instruction *I, bool &IsSimpleLoadStore); 200 201 bool areInstsCompatible(Instruction *I, Instruction *J, 202 bool IsSimpleLoadStore); 203 204 bool trackUsesOfI(DenseSet<Value *> &Users, 205 AliasSetTracker &WriteSet, Instruction *I, 206 Instruction *J, bool UpdateUsers = true, 207 std::multimap<Value *, Value *> *LoadMoveSet = 0); 208 209 void computePairsConnectedTo( 210 std::multimap<Value *, Value *> &CandidatePairs, 211 std::vector<Value *> &PairableInsts, 212 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 213 ValuePair P); 214 215 bool pairsConflict(ValuePair P, ValuePair Q, 216 DenseSet<ValuePair> &PairableInstUsers, 217 std::multimap<ValuePair, ValuePair> *PairableInstUserMap = 0); 218 219 bool pairWillFormCycle(ValuePair P, 220 std::multimap<ValuePair, ValuePair> &PairableInstUsers, 221 DenseSet<ValuePair> &CurrentPairs); 222 223 void pruneTreeFor( 224 std::multimap<Value *, Value *> &CandidatePairs, 225 std::vector<Value *> &PairableInsts, 226 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 227 DenseSet<ValuePair> &PairableInstUsers, 228 std::multimap<ValuePair, ValuePair> &PairableInstUserMap, 229 DenseMap<Value *, Value *> &ChosenPairs, 230 DenseMap<ValuePair, size_t> &Tree, 231 DenseSet<ValuePair> &PrunedTree, ValuePair J, 232 bool UseCycleCheck); 233 234 void buildInitialTreeFor( 235 std::multimap<Value *, Value *> &CandidatePairs, 236 std::vector<Value *> &PairableInsts, 237 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 238 DenseSet<ValuePair> &PairableInstUsers, 239 DenseMap<Value *, Value *> &ChosenPairs, 240 DenseMap<ValuePair, size_t> &Tree, ValuePair J); 241 242 void findBestTreeFor( 243 std::multimap<Value *, Value *> &CandidatePairs, 244 std::vector<Value *> &PairableInsts, 245 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 246 DenseSet<ValuePair> &PairableInstUsers, 247 std::multimap<ValuePair, ValuePair> &PairableInstUserMap, 248 DenseMap<Value *, Value *> &ChosenPairs, 249 DenseSet<ValuePair> &BestTree, size_t &BestMaxDepth, 250 size_t &BestEffSize, VPIteratorPair ChoiceRange, 251 bool UseCycleCheck); 252 253 Value *getReplacementPointerInput(LLVMContext& Context, Instruction *I, 254 Instruction *J, unsigned o, bool &FlipMemInputs); 255 256 void fillNewShuffleMask(LLVMContext& Context, Instruction *J, 257 unsigned NumElem, unsigned MaskOffset, unsigned NumInElem, 258 unsigned IdxOffset, std::vector<Constant*> &Mask); 259 260 Value *getReplacementShuffleMask(LLVMContext& Context, Instruction *I, 261 Instruction *J); 262 263 Value *getReplacementInput(LLVMContext& Context, Instruction *I, 264 Instruction *J, unsigned o, bool FlipMemInputs); 265 266 void getReplacementInputsForPair(LLVMContext& Context, Instruction *I, 267 Instruction *J, SmallVector<Value *, 3> &ReplacedOperands, 268 bool &FlipMemInputs); 269 270 void replaceOutputsOfPair(LLVMContext& Context, Instruction *I, 271 Instruction *J, Instruction *K, 272 Instruction *&InsertionPt, Instruction *&K1, 273 Instruction *&K2, bool &FlipMemInputs); 274 275 void collectPairLoadMoveSet(BasicBlock &BB, 276 DenseMap<Value *, Value *> &ChosenPairs, 277 std::multimap<Value *, Value *> &LoadMoveSet, 278 Instruction *I); 279 280 void collectLoadMoveSet(BasicBlock &BB, 281 std::vector<Value *> &PairableInsts, 282 DenseMap<Value *, Value *> &ChosenPairs, 283 std::multimap<Value *, Value *> &LoadMoveSet); 284 285 bool canMoveUsesOfIAfterJ(BasicBlock &BB, 286 std::multimap<Value *, Value *> &LoadMoveSet, 287 Instruction *I, Instruction *J); 288 289 void moveUsesOfIAfterJ(BasicBlock &BB, 290 std::multimap<Value *, Value *> &LoadMoveSet, 291 Instruction *&InsertionPt, 292 Instruction *I, Instruction *J); 293 294 bool vectorizeBB(BasicBlock &BB) { 295 bool changed = false; 296 // Iterate a sufficient number of times to merge types of size 1 bit, 297 // then 2 bits, then 4, etc. up to half of the target vector width of the 298 // target vector register. 299 for (unsigned v = 2, n = 1; 300 v <= Config.VectorBits && (!Config.MaxIter || n <= Config.MaxIter); 301 v *= 2, ++n) { 302 DEBUG(dbgs() << "BBV: fusing loop #" << n << 303 " for " << BB.getName() << " in " << 304 BB.getParent()->getName() << "...\n"); 305 if (vectorizePairs(BB)) 306 changed = true; 307 else 308 break; 309 } 310 311 DEBUG(dbgs() << "BBV: done!\n"); 312 return changed; 313 } 314 315 virtual bool runOnBasicBlock(BasicBlock &BB) { 316 AA = &getAnalysis<AliasAnalysis>(); 317 SE = &getAnalysis<ScalarEvolution>(); 318 TD = getAnalysisIfAvailable<TargetData>(); 319 320 return vectorizeBB(BB); 321 } 322 323 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 324 BasicBlockPass::getAnalysisUsage(AU); 325 AU.addRequired<AliasAnalysis>(); 326 AU.addRequired<ScalarEvolution>(); 327 AU.addPreserved<AliasAnalysis>(); 328 AU.addPreserved<ScalarEvolution>(); 329 AU.setPreservesCFG(); 330 } 331 332 // This returns the vector type that holds a pair of the provided type. 333 // If the provided type is already a vector, then its length is doubled. 334 static inline VectorType *getVecTypeForPair(Type *ElemTy) { 335 if (VectorType *VTy = dyn_cast<VectorType>(ElemTy)) { 336 unsigned numElem = VTy->getNumElements(); 337 return VectorType::get(ElemTy->getScalarType(), numElem*2); 338 } 339 340 return VectorType::get(ElemTy, 2); 341 } 342 343 // Returns the weight associated with the provided value. A chain of 344 // candidate pairs has a length given by the sum of the weights of its 345 // members (one weight per pair; the weight of each member of the pair 346 // is assumed to be the same). This length is then compared to the 347 // chain-length threshold to determine if a given chain is significant 348 // enough to be vectorized. The length is also used in comparing 349 // candidate chains where longer chains are considered to be better. 350 // Note: when this function returns 0, the resulting instructions are 351 // not actually fused. 352 inline size_t getDepthFactor(Value *V) { 353 // InsertElement and ExtractElement have a depth factor of zero. This is 354 // for two reasons: First, they cannot be usefully fused. Second, because 355 // the pass generates a lot of these, they can confuse the simple metric 356 // used to compare the trees in the next iteration. Thus, giving them a 357 // weight of zero allows the pass to essentially ignore them in 358 // subsequent iterations when looking for vectorization opportunities 359 // while still tracking dependency chains that flow through those 360 // instructions. 361 if (isa<InsertElementInst>(V) || isa<ExtractElementInst>(V)) 362 return 0; 363 364 // Give a load or store half of the required depth so that load/store 365 // pairs will vectorize. 366 if (!Config.NoMemOpBoost && (isa<LoadInst>(V) || isa<StoreInst>(V))) 367 return Config.ReqChainDepth/2; 368 369 return 1; 370 } 371 372 // This determines the relative offset of two loads or stores, returning 373 // true if the offset could be determined to be some constant value. 374 // For example, if OffsetInElmts == 1, then J accesses the memory directly 375 // after I; if OffsetInElmts == -1 then I accesses the memory 376 // directly after J. This function assumes that both instructions 377 // have the same type. 378 bool getPairPtrInfo(Instruction *I, Instruction *J, 379 Value *&IPtr, Value *&JPtr, unsigned &IAlignment, unsigned &JAlignment, 380 int64_t &OffsetInElmts) { 381 OffsetInElmts = 0; 382 if (isa<LoadInst>(I)) { 383 IPtr = cast<LoadInst>(I)->getPointerOperand(); 384 JPtr = cast<LoadInst>(J)->getPointerOperand(); 385 IAlignment = cast<LoadInst>(I)->getAlignment(); 386 JAlignment = cast<LoadInst>(J)->getAlignment(); 387 } else { 388 IPtr = cast<StoreInst>(I)->getPointerOperand(); 389 JPtr = cast<StoreInst>(J)->getPointerOperand(); 390 IAlignment = cast<StoreInst>(I)->getAlignment(); 391 JAlignment = cast<StoreInst>(J)->getAlignment(); 392 } 393 394 const SCEV *IPtrSCEV = SE->getSCEV(IPtr); 395 const SCEV *JPtrSCEV = SE->getSCEV(JPtr); 396 397 // If this is a trivial offset, then we'll get something like 398 // 1*sizeof(type). With target data, which we need anyway, this will get 399 // constant folded into a number. 400 const SCEV *OffsetSCEV = SE->getMinusSCEV(JPtrSCEV, IPtrSCEV); 401 if (const SCEVConstant *ConstOffSCEV = 402 dyn_cast<SCEVConstant>(OffsetSCEV)) { 403 ConstantInt *IntOff = ConstOffSCEV->getValue(); 404 int64_t Offset = IntOff->getSExtValue(); 405 406 Type *VTy = cast<PointerType>(IPtr->getType())->getElementType(); 407 int64_t VTyTSS = (int64_t) TD->getTypeStoreSize(VTy); 408 409 assert(VTy == cast<PointerType>(JPtr->getType())->getElementType()); 410 411 OffsetInElmts = Offset/VTyTSS; 412 return (abs64(Offset) % VTyTSS) == 0; 413 } 414 415 return false; 416 } 417 418 // Returns true if the provided CallInst represents an intrinsic that can 419 // be vectorized. 420 bool isVectorizableIntrinsic(CallInst* I) { 421 Function *F = I->getCalledFunction(); 422 if (!F) return false; 423 424 unsigned IID = F->getIntrinsicID(); 425 if (!IID) return false; 426 427 switch(IID) { 428 default: 429 return false; 430 case Intrinsic::sqrt: 431 case Intrinsic::powi: 432 case Intrinsic::sin: 433 case Intrinsic::cos: 434 case Intrinsic::log: 435 case Intrinsic::log2: 436 case Intrinsic::log10: 437 case Intrinsic::exp: 438 case Intrinsic::exp2: 439 case Intrinsic::pow: 440 return !Config.NoMath; 441 case Intrinsic::fma: 442 return !Config.NoFMA; 443 } 444 } 445 446 // Returns true if J is the second element in some pair referenced by 447 // some multimap pair iterator pair. 448 template <typename V> 449 bool isSecondInIteratorPair(V J, std::pair< 450 typename std::multimap<V, V>::iterator, 451 typename std::multimap<V, V>::iterator> PairRange) { 452 for (typename std::multimap<V, V>::iterator K = PairRange.first; 453 K != PairRange.second; ++K) 454 if (K->second == J) return true; 455 456 return false; 457 } 458 }; 459 460 // This function implements one vectorization iteration on the provided 461 // basic block. It returns true if the block is changed. 462 bool BBVectorize::vectorizePairs(BasicBlock &BB) { 463 bool ShouldContinue; 464 BasicBlock::iterator Start = BB.getFirstInsertionPt(); 465 466 std::vector<Value *> AllPairableInsts; 467 DenseMap<Value *, Value *> AllChosenPairs; 468 469 do { 470 std::vector<Value *> PairableInsts; 471 std::multimap<Value *, Value *> CandidatePairs; 472 ShouldContinue = getCandidatePairs(BB, Start, CandidatePairs, 473 PairableInsts); 474 if (PairableInsts.empty()) continue; 475 476 // Now we have a map of all of the pairable instructions and we need to 477 // select the best possible pairing. A good pairing is one such that the 478 // users of the pair are also paired. This defines a (directed) forest 479 // over the pairs such that two pairs are connected iff the second pair 480 // uses the first. 481 482 // Note that it only matters that both members of the second pair use some 483 // element of the first pair (to allow for splatting). 484 485 std::multimap<ValuePair, ValuePair> ConnectedPairs; 486 computeConnectedPairs(CandidatePairs, PairableInsts, ConnectedPairs); 487 if (ConnectedPairs.empty()) continue; 488 489 // Build the pairable-instruction dependency map 490 DenseSet<ValuePair> PairableInstUsers; 491 buildDepMap(BB, CandidatePairs, PairableInsts, PairableInstUsers); 492 493 // There is now a graph of the connected pairs. For each variable, pick 494 // the pairing with the largest tree meeting the depth requirement on at 495 // least one branch. Then select all pairings that are part of that tree 496 // and remove them from the list of available pairings and pairable 497 // variables. 498 499 DenseMap<Value *, Value *> ChosenPairs; 500 choosePairs(CandidatePairs, PairableInsts, ConnectedPairs, 501 PairableInstUsers, ChosenPairs); 502 503 if (ChosenPairs.empty()) continue; 504 AllPairableInsts.insert(AllPairableInsts.end(), PairableInsts.begin(), 505 PairableInsts.end()); 506 AllChosenPairs.insert(ChosenPairs.begin(), ChosenPairs.end()); 507 } while (ShouldContinue); 508 509 if (AllChosenPairs.empty()) return false; 510 NumFusedOps += AllChosenPairs.size(); 511 512 // A set of pairs has now been selected. It is now necessary to replace the 513 // paired instructions with vector instructions. For this procedure each 514 // operand must be replaced with a vector operand. This vector is formed 515 // by using build_vector on the old operands. The replaced values are then 516 // replaced with a vector_extract on the result. Subsequent optimization 517 // passes should coalesce the build/extract combinations. 518 519 fuseChosenPairs(BB, AllPairableInsts, AllChosenPairs); 520 return true; 521 } 522 523 // This function returns true if the provided instruction is capable of being 524 // fused into a vector instruction. This determination is based only on the 525 // type and other attributes of the instruction. 526 bool BBVectorize::isInstVectorizable(Instruction *I, 527 bool &IsSimpleLoadStore) { 528 IsSimpleLoadStore = false; 529 530 if (CallInst *C = dyn_cast<CallInst>(I)) { 531 if (!isVectorizableIntrinsic(C)) 532 return false; 533 } else if (LoadInst *L = dyn_cast<LoadInst>(I)) { 534 // Vectorize simple loads if possbile: 535 IsSimpleLoadStore = L->isSimple(); 536 if (!IsSimpleLoadStore || Config.NoMemOps) 537 return false; 538 } else if (StoreInst *S = dyn_cast<StoreInst>(I)) { 539 // Vectorize simple stores if possbile: 540 IsSimpleLoadStore = S->isSimple(); 541 if (!IsSimpleLoadStore || Config.NoMemOps) 542 return false; 543 } else if (CastInst *C = dyn_cast<CastInst>(I)) { 544 // We can vectorize casts, but not casts of pointer types, etc. 545 if (Config.NoCasts) 546 return false; 547 548 Type *SrcTy = C->getSrcTy(); 549 if (!SrcTy->isSingleValueType() || SrcTy->isPointerTy()) 550 return false; 551 552 Type *DestTy = C->getDestTy(); 553 if (!DestTy->isSingleValueType() || DestTy->isPointerTy()) 554 return false; 555 } else if (!(I->isBinaryOp() || isa<ShuffleVectorInst>(I) || 556 isa<ExtractElementInst>(I) || isa<InsertElementInst>(I))) { 557 return false; 558 } 559 560 // We can't vectorize memory operations without target data 561 if (TD == 0 && IsSimpleLoadStore) 562 return false; 563 564 Type *T1, *T2; 565 if (isa<StoreInst>(I)) { 566 // For stores, it is the value type, not the pointer type that matters 567 // because the value is what will come from a vector register. 568 569 Value *IVal = cast<StoreInst>(I)->getValueOperand(); 570 T1 = IVal->getType(); 571 } else { 572 T1 = I->getType(); 573 } 574 575 if (I->isCast()) 576 T2 = cast<CastInst>(I)->getSrcTy(); 577 else 578 T2 = T1; 579 580 // Not every type can be vectorized... 581 if (!(VectorType::isValidElementType(T1) || T1->isVectorTy()) || 582 !(VectorType::isValidElementType(T2) || T2->isVectorTy())) 583 return false; 584 585 if (Config.NoInts && (T1->isIntOrIntVectorTy() || T2->isIntOrIntVectorTy())) 586 return false; 587 588 if (Config.NoFloats && (T1->isFPOrFPVectorTy() || T2->isFPOrFPVectorTy())) 589 return false; 590 591 if (T1->getPrimitiveSizeInBits() > Config.VectorBits/2 || 592 T2->getPrimitiveSizeInBits() > Config.VectorBits/2) 593 return false; 594 595 return true; 596 } 597 598 // This function returns true if the two provided instructions are compatible 599 // (meaning that they can be fused into a vector instruction). This assumes 600 // that I has already been determined to be vectorizable and that J is not 601 // in the use tree of I. 602 bool BBVectorize::areInstsCompatible(Instruction *I, Instruction *J, 603 bool IsSimpleLoadStore) { 604 DEBUG(if (DebugInstructionExamination) dbgs() << "BBV: looking at " << *I << 605 " <-> " << *J << "\n"); 606 607 // Loads and stores can be merged if they have different alignments, 608 // but are otherwise the same. 609 LoadInst *LI, *LJ; 610 StoreInst *SI, *SJ; 611 if ((LI = dyn_cast<LoadInst>(I)) && (LJ = dyn_cast<LoadInst>(J))) { 612 if (I->getType() != J->getType()) 613 return false; 614 615 if (LI->getPointerOperand()->getType() != 616 LJ->getPointerOperand()->getType() || 617 LI->isVolatile() != LJ->isVolatile() || 618 LI->getOrdering() != LJ->getOrdering() || 619 LI->getSynchScope() != LJ->getSynchScope()) 620 return false; 621 } else if ((SI = dyn_cast<StoreInst>(I)) && (SJ = dyn_cast<StoreInst>(J))) { 622 if (SI->getValueOperand()->getType() != 623 SJ->getValueOperand()->getType() || 624 SI->getPointerOperand()->getType() != 625 SJ->getPointerOperand()->getType() || 626 SI->isVolatile() != SJ->isVolatile() || 627 SI->getOrdering() != SJ->getOrdering() || 628 SI->getSynchScope() != SJ->getSynchScope()) 629 return false; 630 } else if (!J->isSameOperationAs(I)) { 631 return false; 632 } 633 // FIXME: handle addsub-type operations! 634 635 if (IsSimpleLoadStore) { 636 Value *IPtr, *JPtr; 637 unsigned IAlignment, JAlignment; 638 int64_t OffsetInElmts = 0; 639 if (getPairPtrInfo(I, J, IPtr, JPtr, IAlignment, JAlignment, 640 OffsetInElmts) && abs64(OffsetInElmts) == 1) { 641 if (Config.AlignedOnly) { 642 Type *aType = isa<StoreInst>(I) ? 643 cast<StoreInst>(I)->getValueOperand()->getType() : I->getType(); 644 // An aligned load or store is possible only if the instruction 645 // with the lower offset has an alignment suitable for the 646 // vector type. 647 648 unsigned BottomAlignment = IAlignment; 649 if (OffsetInElmts < 0) BottomAlignment = JAlignment; 650 651 Type *VType = getVecTypeForPair(aType); 652 unsigned VecAlignment = TD->getPrefTypeAlignment(VType); 653 if (BottomAlignment < VecAlignment) 654 return false; 655 } 656 } else { 657 return false; 658 } 659 } else if (isa<ShuffleVectorInst>(I)) { 660 // Only merge two shuffles if they're both constant 661 return isa<Constant>(I->getOperand(2)) && 662 isa<Constant>(J->getOperand(2)); 663 // FIXME: We may want to vectorize non-constant shuffles also. 664 } 665 666 // The powi intrinsic is special because only the first argument is 667 // vectorized, the second arguments must be equal. 668 CallInst *CI = dyn_cast<CallInst>(I); 669 Function *FI; 670 if (CI && (FI = CI->getCalledFunction()) && 671 FI->getIntrinsicID() == Intrinsic::powi) { 672 673 Value *A1I = CI->getArgOperand(1), 674 *A1J = cast<CallInst>(J)->getArgOperand(1); 675 const SCEV *A1ISCEV = SE->getSCEV(A1I), 676 *A1JSCEV = SE->getSCEV(A1J); 677 return (A1ISCEV == A1JSCEV); 678 } 679 680 return true; 681 } 682 683 // Figure out whether or not J uses I and update the users and write-set 684 // structures associated with I. Specifically, Users represents the set of 685 // instructions that depend on I. WriteSet represents the set 686 // of memory locations that are dependent on I. If UpdateUsers is true, 687 // and J uses I, then Users is updated to contain J and WriteSet is updated 688 // to contain any memory locations to which J writes. The function returns 689 // true if J uses I. By default, alias analysis is used to determine 690 // whether J reads from memory that overlaps with a location in WriteSet. 691 // If LoadMoveSet is not null, then it is a previously-computed multimap 692 // where the key is the memory-based user instruction and the value is 693 // the instruction to be compared with I. So, if LoadMoveSet is provided, 694 // then the alias analysis is not used. This is necessary because this 695 // function is called during the process of moving instructions during 696 // vectorization and the results of the alias analysis are not stable during 697 // that process. 698 bool BBVectorize::trackUsesOfI(DenseSet<Value *> &Users, 699 AliasSetTracker &WriteSet, Instruction *I, 700 Instruction *J, bool UpdateUsers, 701 std::multimap<Value *, Value *> *LoadMoveSet) { 702 bool UsesI = false; 703 704 // This instruction may already be marked as a user due, for example, to 705 // being a member of a selected pair. 706 if (Users.count(J)) 707 UsesI = true; 708 709 if (!UsesI) 710 for (User::op_iterator JU = J->op_begin(), JE = J->op_end(); 711 JU != JE; ++JU) { 712 Value *V = *JU; 713 if (I == V || Users.count(V)) { 714 UsesI = true; 715 break; 716 } 717 } 718 if (!UsesI && J->mayReadFromMemory()) { 719 if (LoadMoveSet) { 720 VPIteratorPair JPairRange = LoadMoveSet->equal_range(J); 721 UsesI = isSecondInIteratorPair<Value*>(I, JPairRange); 722 } else { 723 for (AliasSetTracker::iterator W = WriteSet.begin(), 724 WE = WriteSet.end(); W != WE; ++W) { 725 if (W->aliasesUnknownInst(J, *AA)) { 726 UsesI = true; 727 break; 728 } 729 } 730 } 731 } 732 733 if (UsesI && UpdateUsers) { 734 if (J->mayWriteToMemory()) WriteSet.add(J); 735 Users.insert(J); 736 } 737 738 return UsesI; 739 } 740 741 // This function iterates over all instruction pairs in the provided 742 // basic block and collects all candidate pairs for vectorization. 743 bool BBVectorize::getCandidatePairs(BasicBlock &BB, 744 BasicBlock::iterator &Start, 745 std::multimap<Value *, Value *> &CandidatePairs, 746 std::vector<Value *> &PairableInsts) { 747 BasicBlock::iterator E = BB.end(); 748 if (Start == E) return false; 749 750 bool ShouldContinue = false, IAfterStart = false; 751 for (BasicBlock::iterator I = Start++; I != E; ++I) { 752 if (I == Start) IAfterStart = true; 753 754 bool IsSimpleLoadStore; 755 if (!isInstVectorizable(I, IsSimpleLoadStore)) continue; 756 757 // Look for an instruction with which to pair instruction *I... 758 DenseSet<Value *> Users; 759 AliasSetTracker WriteSet(*AA); 760 bool JAfterStart = IAfterStart; 761 BasicBlock::iterator J = llvm::next(I); 762 for (unsigned ss = 0; J != E && ss <= Config.SearchLimit; ++J, ++ss) { 763 if (J == Start) JAfterStart = true; 764 765 // Determine if J uses I, if so, exit the loop. 766 bool UsesI = trackUsesOfI(Users, WriteSet, I, J, !Config.FastDep); 767 if (Config.FastDep) { 768 // Note: For this heuristic to be effective, independent operations 769 // must tend to be intermixed. This is likely to be true from some 770 // kinds of grouped loop unrolling (but not the generic LLVM pass), 771 // but otherwise may require some kind of reordering pass. 772 773 // When using fast dependency analysis, 774 // stop searching after first use: 775 if (UsesI) break; 776 } else { 777 if (UsesI) continue; 778 } 779 780 // J does not use I, and comes before the first use of I, so it can be 781 // merged with I if the instructions are compatible. 782 if (!areInstsCompatible(I, J, IsSimpleLoadStore)) continue; 783 784 // J is a candidate for merging with I. 785 if (!PairableInsts.size() || 786 PairableInsts[PairableInsts.size()-1] != I) { 787 PairableInsts.push_back(I); 788 } 789 790 CandidatePairs.insert(ValuePair(I, J)); 791 792 // The next call to this function must start after the last instruction 793 // selected during this invocation. 794 if (JAfterStart) { 795 Start = llvm::next(J); 796 IAfterStart = JAfterStart = false; 797 } 798 799 DEBUG(if (DebugCandidateSelection) dbgs() << "BBV: candidate pair " 800 << *I << " <-> " << *J << "\n"); 801 802 // If we have already found too many pairs, break here and this function 803 // will be called again starting after the last instruction selected 804 // during this invocation. 805 if (PairableInsts.size() >= Config.MaxInsts) { 806 ShouldContinue = true; 807 break; 808 } 809 } 810 811 if (ShouldContinue) 812 break; 813 } 814 815 DEBUG(dbgs() << "BBV: found " << PairableInsts.size() 816 << " instructions with candidate pairs\n"); 817 818 return ShouldContinue; 819 } 820 821 // Finds candidate pairs connected to the pair P = <PI, PJ>. This means that 822 // it looks for pairs such that both members have an input which is an 823 // output of PI or PJ. 824 void BBVectorize::computePairsConnectedTo( 825 std::multimap<Value *, Value *> &CandidatePairs, 826 std::vector<Value *> &PairableInsts, 827 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 828 ValuePair P) { 829 // For each possible pairing for this variable, look at the uses of 830 // the first value... 831 for (Value::use_iterator I = P.first->use_begin(), 832 E = P.first->use_end(); I != E; ++I) { 833 VPIteratorPair IPairRange = CandidatePairs.equal_range(*I); 834 835 // For each use of the first variable, look for uses of the second 836 // variable... 837 for (Value::use_iterator J = P.second->use_begin(), 838 E2 = P.second->use_end(); J != E2; ++J) { 839 VPIteratorPair JPairRange = CandidatePairs.equal_range(*J); 840 841 // Look for <I, J>: 842 if (isSecondInIteratorPair<Value*>(*J, IPairRange)) 843 ConnectedPairs.insert(VPPair(P, ValuePair(*I, *J))); 844 845 // Look for <J, I>: 846 if (isSecondInIteratorPair<Value*>(*I, JPairRange)) 847 ConnectedPairs.insert(VPPair(P, ValuePair(*J, *I))); 848 } 849 850 if (Config.SplatBreaksChain) continue; 851 // Look for cases where just the first value in the pair is used by 852 // both members of another pair (splatting). 853 for (Value::use_iterator J = P.first->use_begin(); J != E; ++J) { 854 if (isSecondInIteratorPair<Value*>(*J, IPairRange)) 855 ConnectedPairs.insert(VPPair(P, ValuePair(*I, *J))); 856 } 857 } 858 859 if (Config.SplatBreaksChain) return; 860 // Look for cases where just the second value in the pair is used by 861 // both members of another pair (splatting). 862 for (Value::use_iterator I = P.second->use_begin(), 863 E = P.second->use_end(); I != E; ++I) { 864 VPIteratorPair IPairRange = CandidatePairs.equal_range(*I); 865 866 for (Value::use_iterator J = P.second->use_begin(); J != E; ++J) { 867 if (isSecondInIteratorPair<Value*>(*J, IPairRange)) 868 ConnectedPairs.insert(VPPair(P, ValuePair(*I, *J))); 869 } 870 } 871 } 872 873 // This function figures out which pairs are connected. Two pairs are 874 // connected if some output of the first pair forms an input to both members 875 // of the second pair. 876 void BBVectorize::computeConnectedPairs( 877 std::multimap<Value *, Value *> &CandidatePairs, 878 std::vector<Value *> &PairableInsts, 879 std::multimap<ValuePair, ValuePair> &ConnectedPairs) { 880 881 for (std::vector<Value *>::iterator PI = PairableInsts.begin(), 882 PE = PairableInsts.end(); PI != PE; ++PI) { 883 VPIteratorPair choiceRange = CandidatePairs.equal_range(*PI); 884 885 for (std::multimap<Value *, Value *>::iterator P = choiceRange.first; 886 P != choiceRange.second; ++P) 887 computePairsConnectedTo(CandidatePairs, PairableInsts, 888 ConnectedPairs, *P); 889 } 890 891 DEBUG(dbgs() << "BBV: found " << ConnectedPairs.size() 892 << " pair connections.\n"); 893 } 894 895 // This function builds a set of use tuples such that <A, B> is in the set 896 // if B is in the use tree of A. If B is in the use tree of A, then B 897 // depends on the output of A. 898 void BBVectorize::buildDepMap( 899 BasicBlock &BB, 900 std::multimap<Value *, Value *> &CandidatePairs, 901 std::vector<Value *> &PairableInsts, 902 DenseSet<ValuePair> &PairableInstUsers) { 903 DenseSet<Value *> IsInPair; 904 for (std::multimap<Value *, Value *>::iterator C = CandidatePairs.begin(), 905 E = CandidatePairs.end(); C != E; ++C) { 906 IsInPair.insert(C->first); 907 IsInPair.insert(C->second); 908 } 909 910 // Iterate through the basic block, recording all Users of each 911 // pairable instruction. 912 913 BasicBlock::iterator E = BB.end(); 914 for (BasicBlock::iterator I = BB.getFirstInsertionPt(); I != E; ++I) { 915 if (IsInPair.find(I) == IsInPair.end()) continue; 916 917 DenseSet<Value *> Users; 918 AliasSetTracker WriteSet(*AA); 919 for (BasicBlock::iterator J = llvm::next(I); J != E; ++J) 920 (void) trackUsesOfI(Users, WriteSet, I, J); 921 922 for (DenseSet<Value *>::iterator U = Users.begin(), E = Users.end(); 923 U != E; ++U) 924 PairableInstUsers.insert(ValuePair(I, *U)); 925 } 926 } 927 928 // Returns true if an input to pair P is an output of pair Q and also an 929 // input of pair Q is an output of pair P. If this is the case, then these 930 // two pairs cannot be simultaneously fused. 931 bool BBVectorize::pairsConflict(ValuePair P, ValuePair Q, 932 DenseSet<ValuePair> &PairableInstUsers, 933 std::multimap<ValuePair, ValuePair> *PairableInstUserMap) { 934 // Two pairs are in conflict if they are mutual Users of eachother. 935 bool QUsesP = PairableInstUsers.count(ValuePair(P.first, Q.first)) || 936 PairableInstUsers.count(ValuePair(P.first, Q.second)) || 937 PairableInstUsers.count(ValuePair(P.second, Q.first)) || 938 PairableInstUsers.count(ValuePair(P.second, Q.second)); 939 bool PUsesQ = PairableInstUsers.count(ValuePair(Q.first, P.first)) || 940 PairableInstUsers.count(ValuePair(Q.first, P.second)) || 941 PairableInstUsers.count(ValuePair(Q.second, P.first)) || 942 PairableInstUsers.count(ValuePair(Q.second, P.second)); 943 if (PairableInstUserMap) { 944 // FIXME: The expensive part of the cycle check is not so much the cycle 945 // check itself but this edge insertion procedure. This needs some 946 // profiling and probably a different data structure (same is true of 947 // most uses of std::multimap). 948 if (PUsesQ) { 949 VPPIteratorPair QPairRange = PairableInstUserMap->equal_range(Q); 950 if (!isSecondInIteratorPair(P, QPairRange)) 951 PairableInstUserMap->insert(VPPair(Q, P)); 952 } 953 if (QUsesP) { 954 VPPIteratorPair PPairRange = PairableInstUserMap->equal_range(P); 955 if (!isSecondInIteratorPair(Q, PPairRange)) 956 PairableInstUserMap->insert(VPPair(P, Q)); 957 } 958 } 959 960 return (QUsesP && PUsesQ); 961 } 962 963 // This function walks the use graph of current pairs to see if, starting 964 // from P, the walk returns to P. 965 bool BBVectorize::pairWillFormCycle(ValuePair P, 966 std::multimap<ValuePair, ValuePair> &PairableInstUserMap, 967 DenseSet<ValuePair> &CurrentPairs) { 968 DEBUG(if (DebugCycleCheck) 969 dbgs() << "BBV: starting cycle check for : " << *P.first << " <-> " 970 << *P.second << "\n"); 971 // A lookup table of visisted pairs is kept because the PairableInstUserMap 972 // contains non-direct associations. 973 DenseSet<ValuePair> Visited; 974 SmallVector<ValuePair, 32> Q; 975 // General depth-first post-order traversal: 976 Q.push_back(P); 977 do { 978 ValuePair QTop = Q.pop_back_val(); 979 Visited.insert(QTop); 980 981 DEBUG(if (DebugCycleCheck) 982 dbgs() << "BBV: cycle check visiting: " << *QTop.first << " <-> " 983 << *QTop.second << "\n"); 984 VPPIteratorPair QPairRange = PairableInstUserMap.equal_range(QTop); 985 for (std::multimap<ValuePair, ValuePair>::iterator C = QPairRange.first; 986 C != QPairRange.second; ++C) { 987 if (C->second == P) { 988 DEBUG(dbgs() 989 << "BBV: rejected to prevent non-trivial cycle formation: " 990 << *C->first.first << " <-> " << *C->first.second << "\n"); 991 return true; 992 } 993 994 if (CurrentPairs.count(C->second) && !Visited.count(C->second)) 995 Q.push_back(C->second); 996 } 997 } while (!Q.empty()); 998 999 return false; 1000 } 1001 1002 // This function builds the initial tree of connected pairs with the 1003 // pair J at the root. 1004 void BBVectorize::buildInitialTreeFor( 1005 std::multimap<Value *, Value *> &CandidatePairs, 1006 std::vector<Value *> &PairableInsts, 1007 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 1008 DenseSet<ValuePair> &PairableInstUsers, 1009 DenseMap<Value *, Value *> &ChosenPairs, 1010 DenseMap<ValuePair, size_t> &Tree, ValuePair J) { 1011 // Each of these pairs is viewed as the root node of a Tree. The Tree 1012 // is then walked (depth-first). As this happens, we keep track of 1013 // the pairs that compose the Tree and the maximum depth of the Tree. 1014 SmallVector<ValuePairWithDepth, 32> Q; 1015 // General depth-first post-order traversal: 1016 Q.push_back(ValuePairWithDepth(J, getDepthFactor(J.first))); 1017 do { 1018 ValuePairWithDepth QTop = Q.back(); 1019 1020 // Push each child onto the queue: 1021 bool MoreChildren = false; 1022 size_t MaxChildDepth = QTop.second; 1023 VPPIteratorPair qtRange = ConnectedPairs.equal_range(QTop.first); 1024 for (std::multimap<ValuePair, ValuePair>::iterator k = qtRange.first; 1025 k != qtRange.second; ++k) { 1026 // Make sure that this child pair is still a candidate: 1027 bool IsStillCand = false; 1028 VPIteratorPair checkRange = 1029 CandidatePairs.equal_range(k->second.first); 1030 for (std::multimap<Value *, Value *>::iterator m = checkRange.first; 1031 m != checkRange.second; ++m) { 1032 if (m->second == k->second.second) { 1033 IsStillCand = true; 1034 break; 1035 } 1036 } 1037 1038 if (IsStillCand) { 1039 DenseMap<ValuePair, size_t>::iterator C = Tree.find(k->second); 1040 if (C == Tree.end()) { 1041 size_t d = getDepthFactor(k->second.first); 1042 Q.push_back(ValuePairWithDepth(k->second, QTop.second+d)); 1043 MoreChildren = true; 1044 } else { 1045 MaxChildDepth = std::max(MaxChildDepth, C->second); 1046 } 1047 } 1048 } 1049 1050 if (!MoreChildren) { 1051 // Record the current pair as part of the Tree: 1052 Tree.insert(ValuePairWithDepth(QTop.first, MaxChildDepth)); 1053 Q.pop_back(); 1054 } 1055 } while (!Q.empty()); 1056 } 1057 1058 // Given some initial tree, prune it by removing conflicting pairs (pairs 1059 // that cannot be simultaneously chosen for vectorization). 1060 void BBVectorize::pruneTreeFor( 1061 std::multimap<Value *, Value *> &CandidatePairs, 1062 std::vector<Value *> &PairableInsts, 1063 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 1064 DenseSet<ValuePair> &PairableInstUsers, 1065 std::multimap<ValuePair, ValuePair> &PairableInstUserMap, 1066 DenseMap<Value *, Value *> &ChosenPairs, 1067 DenseMap<ValuePair, size_t> &Tree, 1068 DenseSet<ValuePair> &PrunedTree, ValuePair J, 1069 bool UseCycleCheck) { 1070 SmallVector<ValuePairWithDepth, 32> Q; 1071 // General depth-first post-order traversal: 1072 Q.push_back(ValuePairWithDepth(J, getDepthFactor(J.first))); 1073 do { 1074 ValuePairWithDepth QTop = Q.pop_back_val(); 1075 PrunedTree.insert(QTop.first); 1076 1077 // Visit each child, pruning as necessary... 1078 DenseMap<ValuePair, size_t> BestChildren; 1079 VPPIteratorPair QTopRange = ConnectedPairs.equal_range(QTop.first); 1080 for (std::multimap<ValuePair, ValuePair>::iterator K = QTopRange.first; 1081 K != QTopRange.second; ++K) { 1082 DenseMap<ValuePair, size_t>::iterator C = Tree.find(K->second); 1083 if (C == Tree.end()) continue; 1084 1085 // This child is in the Tree, now we need to make sure it is the 1086 // best of any conflicting children. There could be multiple 1087 // conflicting children, so first, determine if we're keeping 1088 // this child, then delete conflicting children as necessary. 1089 1090 // It is also necessary to guard against pairing-induced 1091 // dependencies. Consider instructions a .. x .. y .. b 1092 // such that (a,b) are to be fused and (x,y) are to be fused 1093 // but a is an input to x and b is an output from y. This 1094 // means that y cannot be moved after b but x must be moved 1095 // after b for (a,b) to be fused. In other words, after 1096 // fusing (a,b) we have y .. a/b .. x where y is an input 1097 // to a/b and x is an output to a/b: x and y can no longer 1098 // be legally fused. To prevent this condition, we must 1099 // make sure that a child pair added to the Tree is not 1100 // both an input and output of an already-selected pair. 1101 1102 // Pairing-induced dependencies can also form from more complicated 1103 // cycles. The pair vs. pair conflicts are easy to check, and so 1104 // that is done explicitly for "fast rejection", and because for 1105 // child vs. child conflicts, we may prefer to keep the current 1106 // pair in preference to the already-selected child. 1107 DenseSet<ValuePair> CurrentPairs; 1108 1109 bool CanAdd = true; 1110 for (DenseMap<ValuePair, size_t>::iterator C2 1111 = BestChildren.begin(), E2 = BestChildren.end(); 1112 C2 != E2; ++C2) { 1113 if (C2->first.first == C->first.first || 1114 C2->first.first == C->first.second || 1115 C2->first.second == C->first.first || 1116 C2->first.second == C->first.second || 1117 pairsConflict(C2->first, C->first, PairableInstUsers, 1118 UseCycleCheck ? &PairableInstUserMap : 0)) { 1119 if (C2->second >= C->second) { 1120 CanAdd = false; 1121 break; 1122 } 1123 1124 CurrentPairs.insert(C2->first); 1125 } 1126 } 1127 if (!CanAdd) continue; 1128 1129 // Even worse, this child could conflict with another node already 1130 // selected for the Tree. If that is the case, ignore this child. 1131 for (DenseSet<ValuePair>::iterator T = PrunedTree.begin(), 1132 E2 = PrunedTree.end(); T != E2; ++T) { 1133 if (T->first == C->first.first || 1134 T->first == C->first.second || 1135 T->second == C->first.first || 1136 T->second == C->first.second || 1137 pairsConflict(*T, C->first, PairableInstUsers, 1138 UseCycleCheck ? &PairableInstUserMap : 0)) { 1139 CanAdd = false; 1140 break; 1141 } 1142 1143 CurrentPairs.insert(*T); 1144 } 1145 if (!CanAdd) continue; 1146 1147 // And check the queue too... 1148 for (SmallVector<ValuePairWithDepth, 32>::iterator C2 = Q.begin(), 1149 E2 = Q.end(); C2 != E2; ++C2) { 1150 if (C2->first.first == C->first.first || 1151 C2->first.first == C->first.second || 1152 C2->first.second == C->first.first || 1153 C2->first.second == C->first.second || 1154 pairsConflict(C2->first, C->first, PairableInstUsers, 1155 UseCycleCheck ? &PairableInstUserMap : 0)) { 1156 CanAdd = false; 1157 break; 1158 } 1159 1160 CurrentPairs.insert(C2->first); 1161 } 1162 if (!CanAdd) continue; 1163 1164 // Last but not least, check for a conflict with any of the 1165 // already-chosen pairs. 1166 for (DenseMap<Value *, Value *>::iterator C2 = 1167 ChosenPairs.begin(), E2 = ChosenPairs.end(); 1168 C2 != E2; ++C2) { 1169 if (pairsConflict(*C2, C->first, PairableInstUsers, 1170 UseCycleCheck ? &PairableInstUserMap : 0)) { 1171 CanAdd = false; 1172 break; 1173 } 1174 1175 CurrentPairs.insert(*C2); 1176 } 1177 if (!CanAdd) continue; 1178 1179 // To check for non-trivial cycles formed by the addition of the 1180 // current pair we've formed a list of all relevant pairs, now use a 1181 // graph walk to check for a cycle. We start from the current pair and 1182 // walk the use tree to see if we again reach the current pair. If we 1183 // do, then the current pair is rejected. 1184 1185 // FIXME: It may be more efficient to use a topological-ordering 1186 // algorithm to improve the cycle check. This should be investigated. 1187 if (UseCycleCheck && 1188 pairWillFormCycle(C->first, PairableInstUserMap, CurrentPairs)) 1189 continue; 1190 1191 // This child can be added, but we may have chosen it in preference 1192 // to an already-selected child. Check for this here, and if a 1193 // conflict is found, then remove the previously-selected child 1194 // before adding this one in its place. 1195 for (DenseMap<ValuePair, size_t>::iterator C2 1196 = BestChildren.begin(); C2 != BestChildren.end();) { 1197 if (C2->first.first == C->first.first || 1198 C2->first.first == C->first.second || 1199 C2->first.second == C->first.first || 1200 C2->first.second == C->first.second || 1201 pairsConflict(C2->first, C->first, PairableInstUsers)) 1202 BestChildren.erase(C2++); 1203 else 1204 ++C2; 1205 } 1206 1207 BestChildren.insert(ValuePairWithDepth(C->first, C->second)); 1208 } 1209 1210 for (DenseMap<ValuePair, size_t>::iterator C 1211 = BestChildren.begin(), E2 = BestChildren.end(); 1212 C != E2; ++C) { 1213 size_t DepthF = getDepthFactor(C->first.first); 1214 Q.push_back(ValuePairWithDepth(C->first, QTop.second+DepthF)); 1215 } 1216 } while (!Q.empty()); 1217 } 1218 1219 // This function finds the best tree of mututally-compatible connected 1220 // pairs, given the choice of root pairs as an iterator range. 1221 void BBVectorize::findBestTreeFor( 1222 std::multimap<Value *, Value *> &CandidatePairs, 1223 std::vector<Value *> &PairableInsts, 1224 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 1225 DenseSet<ValuePair> &PairableInstUsers, 1226 std::multimap<ValuePair, ValuePair> &PairableInstUserMap, 1227 DenseMap<Value *, Value *> &ChosenPairs, 1228 DenseSet<ValuePair> &BestTree, size_t &BestMaxDepth, 1229 size_t &BestEffSize, VPIteratorPair ChoiceRange, 1230 bool UseCycleCheck) { 1231 for (std::multimap<Value *, Value *>::iterator J = ChoiceRange.first; 1232 J != ChoiceRange.second; ++J) { 1233 1234 // Before going any further, make sure that this pair does not 1235 // conflict with any already-selected pairs (see comment below 1236 // near the Tree pruning for more details). 1237 DenseSet<ValuePair> ChosenPairSet; 1238 bool DoesConflict = false; 1239 for (DenseMap<Value *, Value *>::iterator C = ChosenPairs.begin(), 1240 E = ChosenPairs.end(); C != E; ++C) { 1241 if (pairsConflict(*C, *J, PairableInstUsers, 1242 UseCycleCheck ? &PairableInstUserMap : 0)) { 1243 DoesConflict = true; 1244 break; 1245 } 1246 1247 ChosenPairSet.insert(*C); 1248 } 1249 if (DoesConflict) continue; 1250 1251 if (UseCycleCheck && 1252 pairWillFormCycle(*J, PairableInstUserMap, ChosenPairSet)) 1253 continue; 1254 1255 DenseMap<ValuePair, size_t> Tree; 1256 buildInitialTreeFor(CandidatePairs, PairableInsts, ConnectedPairs, 1257 PairableInstUsers, ChosenPairs, Tree, *J); 1258 1259 // Because we'll keep the child with the largest depth, the largest 1260 // depth is still the same in the unpruned Tree. 1261 size_t MaxDepth = Tree.lookup(*J); 1262 1263 DEBUG(if (DebugPairSelection) dbgs() << "BBV: found Tree for pair {" 1264 << *J->first << " <-> " << *J->second << "} of depth " << 1265 MaxDepth << " and size " << Tree.size() << "\n"); 1266 1267 // At this point the Tree has been constructed, but, may contain 1268 // contradictory children (meaning that different children of 1269 // some tree node may be attempting to fuse the same instruction). 1270 // So now we walk the tree again, in the case of a conflict, 1271 // keep only the child with the largest depth. To break a tie, 1272 // favor the first child. 1273 1274 DenseSet<ValuePair> PrunedTree; 1275 pruneTreeFor(CandidatePairs, PairableInsts, ConnectedPairs, 1276 PairableInstUsers, PairableInstUserMap, ChosenPairs, Tree, 1277 PrunedTree, *J, UseCycleCheck); 1278 1279 size_t EffSize = 0; 1280 for (DenseSet<ValuePair>::iterator S = PrunedTree.begin(), 1281 E = PrunedTree.end(); S != E; ++S) 1282 EffSize += getDepthFactor(S->first); 1283 1284 DEBUG(if (DebugPairSelection) 1285 dbgs() << "BBV: found pruned Tree for pair {" 1286 << *J->first << " <-> " << *J->second << "} of depth " << 1287 MaxDepth << " and size " << PrunedTree.size() << 1288 " (effective size: " << EffSize << ")\n"); 1289 if (MaxDepth >= Config.ReqChainDepth && EffSize > BestEffSize) { 1290 BestMaxDepth = MaxDepth; 1291 BestEffSize = EffSize; 1292 BestTree = PrunedTree; 1293 } 1294 } 1295 } 1296 1297 // Given the list of candidate pairs, this function selects those 1298 // that will be fused into vector instructions. 1299 void BBVectorize::choosePairs( 1300 std::multimap<Value *, Value *> &CandidatePairs, 1301 std::vector<Value *> &PairableInsts, 1302 std::multimap<ValuePair, ValuePair> &ConnectedPairs, 1303 DenseSet<ValuePair> &PairableInstUsers, 1304 DenseMap<Value *, Value *>& ChosenPairs) { 1305 bool UseCycleCheck = 1306 CandidatePairs.size() <= Config.MaxCandPairsForCycleCheck; 1307 std::multimap<ValuePair, ValuePair> PairableInstUserMap; 1308 for (std::vector<Value *>::iterator I = PairableInsts.begin(), 1309 E = PairableInsts.end(); I != E; ++I) { 1310 // The number of possible pairings for this variable: 1311 size_t NumChoices = CandidatePairs.count(*I); 1312 if (!NumChoices) continue; 1313 1314 VPIteratorPair ChoiceRange = CandidatePairs.equal_range(*I); 1315 1316 // The best pair to choose and its tree: 1317 size_t BestMaxDepth = 0, BestEffSize = 0; 1318 DenseSet<ValuePair> BestTree; 1319 findBestTreeFor(CandidatePairs, PairableInsts, ConnectedPairs, 1320 PairableInstUsers, PairableInstUserMap, ChosenPairs, 1321 BestTree, BestMaxDepth, BestEffSize, ChoiceRange, 1322 UseCycleCheck); 1323 1324 // A tree has been chosen (or not) at this point. If no tree was 1325 // chosen, then this instruction, I, cannot be paired (and is no longer 1326 // considered). 1327 1328 DEBUG(if (BestTree.size() > 0) 1329 dbgs() << "BBV: selected pairs in the best tree for: " 1330 << *cast<Instruction>(*I) << "\n"); 1331 1332 for (DenseSet<ValuePair>::iterator S = BestTree.begin(), 1333 SE2 = BestTree.end(); S != SE2; ++S) { 1334 // Insert the members of this tree into the list of chosen pairs. 1335 ChosenPairs.insert(ValuePair(S->first, S->second)); 1336 DEBUG(dbgs() << "BBV: selected pair: " << *S->first << " <-> " << 1337 *S->second << "\n"); 1338 1339 // Remove all candidate pairs that have values in the chosen tree. 1340 for (std::multimap<Value *, Value *>::iterator K = 1341 CandidatePairs.begin(); K != CandidatePairs.end();) { 1342 if (K->first == S->first || K->second == S->first || 1343 K->second == S->second || K->first == S->second) { 1344 // Don't remove the actual pair chosen so that it can be used 1345 // in subsequent tree selections. 1346 if (!(K->first == S->first && K->second == S->second)) 1347 CandidatePairs.erase(K++); 1348 else 1349 ++K; 1350 } else { 1351 ++K; 1352 } 1353 } 1354 } 1355 } 1356 1357 DEBUG(dbgs() << "BBV: selected " << ChosenPairs.size() << " pairs.\n"); 1358 } 1359 1360 std::string getReplacementName(Instruction *I, bool IsInput, unsigned o, 1361 unsigned n = 0) { 1362 if (!I->hasName()) 1363 return ""; 1364 1365 return (I->getName() + (IsInput ? ".v.i" : ".v.r") + utostr(o) + 1366 (n > 0 ? "." + utostr(n) : "")).str(); 1367 } 1368 1369 // Returns the value that is to be used as the pointer input to the vector 1370 // instruction that fuses I with J. 1371 Value *BBVectorize::getReplacementPointerInput(LLVMContext& Context, 1372 Instruction *I, Instruction *J, unsigned o, 1373 bool &FlipMemInputs) { 1374 Value *IPtr, *JPtr; 1375 unsigned IAlignment, JAlignment; 1376 int64_t OffsetInElmts; 1377 (void) getPairPtrInfo(I, J, IPtr, JPtr, IAlignment, JAlignment, 1378 OffsetInElmts); 1379 1380 // The pointer value is taken to be the one with the lowest offset. 1381 Value *VPtr; 1382 if (OffsetInElmts > 0) { 1383 VPtr = IPtr; 1384 } else { 1385 FlipMemInputs = true; 1386 VPtr = JPtr; 1387 } 1388 1389 Type *ArgType = cast<PointerType>(IPtr->getType())->getElementType(); 1390 Type *VArgType = getVecTypeForPair(ArgType); 1391 Type *VArgPtrType = PointerType::get(VArgType, 1392 cast<PointerType>(IPtr->getType())->getAddressSpace()); 1393 return new BitCastInst(VPtr, VArgPtrType, getReplacementName(I, true, o), 1394 /* insert before */ FlipMemInputs ? J : I); 1395 } 1396 1397 void BBVectorize::fillNewShuffleMask(LLVMContext& Context, Instruction *J, 1398 unsigned NumElem, unsigned MaskOffset, unsigned NumInElem, 1399 unsigned IdxOffset, std::vector<Constant*> &Mask) { 1400 for (unsigned v = 0; v < NumElem/2; ++v) { 1401 int m = cast<ShuffleVectorInst>(J)->getMaskValue(v); 1402 if (m < 0) { 1403 Mask[v+MaskOffset] = UndefValue::get(Type::getInt32Ty(Context)); 1404 } else { 1405 unsigned mm = m + (int) IdxOffset; 1406 if (m >= (int) NumInElem) 1407 mm += (int) NumInElem; 1408 1409 Mask[v+MaskOffset] = 1410 ConstantInt::get(Type::getInt32Ty(Context), mm); 1411 } 1412 } 1413 } 1414 1415 // Returns the value that is to be used as the vector-shuffle mask to the 1416 // vector instruction that fuses I with J. 1417 Value *BBVectorize::getReplacementShuffleMask(LLVMContext& Context, 1418 Instruction *I, Instruction *J) { 1419 // This is the shuffle mask. We need to append the second 1420 // mask to the first, and the numbers need to be adjusted. 1421 1422 Type *ArgType = I->getType(); 1423 Type *VArgType = getVecTypeForPair(ArgType); 1424 1425 // Get the total number of elements in the fused vector type. 1426 // By definition, this must equal the number of elements in 1427 // the final mask. 1428 unsigned NumElem = cast<VectorType>(VArgType)->getNumElements(); 1429 std::vector<Constant*> Mask(NumElem); 1430 1431 Type *OpType = I->getOperand(0)->getType(); 1432 unsigned NumInElem = cast<VectorType>(OpType)->getNumElements(); 1433 1434 // For the mask from the first pair... 1435 fillNewShuffleMask(Context, I, NumElem, 0, NumInElem, 0, Mask); 1436 1437 // For the mask from the second pair... 1438 fillNewShuffleMask(Context, J, NumElem, NumElem/2, NumInElem, NumInElem, 1439 Mask); 1440 1441 return ConstantVector::get(Mask); 1442 } 1443 1444 // Returns the value to be used as the specified operand of the vector 1445 // instruction that fuses I with J. 1446 Value *BBVectorize::getReplacementInput(LLVMContext& Context, Instruction *I, 1447 Instruction *J, unsigned o, bool FlipMemInputs) { 1448 Value *CV0 = ConstantInt::get(Type::getInt32Ty(Context), 0); 1449 Value *CV1 = ConstantInt::get(Type::getInt32Ty(Context), 1); 1450 1451 // Compute the fused vector type for this operand 1452 Type *ArgType = I->getOperand(o)->getType(); 1453 VectorType *VArgType = getVecTypeForPair(ArgType); 1454 1455 Instruction *L = I, *H = J; 1456 if (FlipMemInputs) { 1457 L = J; 1458 H = I; 1459 } 1460 1461 if (ArgType->isVectorTy()) { 1462 unsigned numElem = cast<VectorType>(VArgType)->getNumElements(); 1463 std::vector<Constant*> Mask(numElem); 1464 for (unsigned v = 0; v < numElem; ++v) 1465 Mask[v] = ConstantInt::get(Type::getInt32Ty(Context), v); 1466 1467 Instruction *BV = new ShuffleVectorInst(L->getOperand(o), 1468 H->getOperand(o), 1469 ConstantVector::get(Mask), 1470 getReplacementName(I, true, o)); 1471 BV->insertBefore(J); 1472 return BV; 1473 } 1474 1475 // If these two inputs are the output of another vector instruction, 1476 // then we should use that output directly. It might be necessary to 1477 // permute it first. [When pairings are fused recursively, you can 1478 // end up with cases where a large vector is decomposed into scalars 1479 // using extractelement instructions, then built into size-2 1480 // vectors using insertelement and the into larger vectors using 1481 // shuffles. InstCombine does not simplify all of these cases well, 1482 // and so we make sure that shuffles are generated here when possible. 1483 ExtractElementInst *LEE 1484 = dyn_cast<ExtractElementInst>(L->getOperand(o)); 1485 ExtractElementInst *HEE 1486 = dyn_cast<ExtractElementInst>(H->getOperand(o)); 1487 1488 if (LEE && HEE && 1489 LEE->getOperand(0)->getType() == HEE->getOperand(0)->getType()) { 1490 VectorType *EEType = cast<VectorType>(LEE->getOperand(0)->getType()); 1491 unsigned LowIndx = cast<ConstantInt>(LEE->getOperand(1))->getZExtValue(); 1492 unsigned HighIndx = cast<ConstantInt>(HEE->getOperand(1))->getZExtValue(); 1493 if (LEE->getOperand(0) == HEE->getOperand(0)) { 1494 if (LowIndx == 0 && HighIndx == 1) 1495 return LEE->getOperand(0); 1496 1497 std::vector<Constant*> Mask(2); 1498 Mask[0] = ConstantInt::get(Type::getInt32Ty(Context), LowIndx); 1499 Mask[1] = ConstantInt::get(Type::getInt32Ty(Context), HighIndx); 1500 1501 Instruction *BV = new ShuffleVectorInst(LEE->getOperand(0), 1502 UndefValue::get(EEType), 1503 ConstantVector::get(Mask), 1504 getReplacementName(I, true, o)); 1505 BV->insertBefore(J); 1506 return BV; 1507 } 1508 1509 std::vector<Constant*> Mask(2); 1510 HighIndx += EEType->getNumElements(); 1511 Mask[0] = ConstantInt::get(Type::getInt32Ty(Context), LowIndx); 1512 Mask[1] = ConstantInt::get(Type::getInt32Ty(Context), HighIndx); 1513 1514 Instruction *BV = new ShuffleVectorInst(LEE->getOperand(0), 1515 HEE->getOperand(0), 1516 ConstantVector::get(Mask), 1517 getReplacementName(I, true, o)); 1518 BV->insertBefore(J); 1519 return BV; 1520 } 1521 1522 Instruction *BV1 = InsertElementInst::Create( 1523 UndefValue::get(VArgType), 1524 L->getOperand(o), CV0, 1525 getReplacementName(I, true, o, 1)); 1526 BV1->insertBefore(I); 1527 Instruction *BV2 = InsertElementInst::Create(BV1, H->getOperand(o), 1528 CV1, 1529 getReplacementName(I, true, o, 2)); 1530 BV2->insertBefore(J); 1531 return BV2; 1532 } 1533 1534 // This function creates an array of values that will be used as the inputs 1535 // to the vector instruction that fuses I with J. 1536 void BBVectorize::getReplacementInputsForPair(LLVMContext& Context, 1537 Instruction *I, Instruction *J, 1538 SmallVector<Value *, 3> &ReplacedOperands, 1539 bool &FlipMemInputs) { 1540 FlipMemInputs = false; 1541 unsigned NumOperands = I->getNumOperands(); 1542 1543 for (unsigned p = 0, o = NumOperands-1; p < NumOperands; ++p, --o) { 1544 // Iterate backward so that we look at the store pointer 1545 // first and know whether or not we need to flip the inputs. 1546 1547 if (isa<LoadInst>(I) || (o == 1 && isa<StoreInst>(I))) { 1548 // This is the pointer for a load/store instruction. 1549 ReplacedOperands[o] = getReplacementPointerInput(Context, I, J, o, 1550 FlipMemInputs); 1551 continue; 1552 } else if (isa<CallInst>(I)) { 1553 Function *F = cast<CallInst>(I)->getCalledFunction(); 1554 unsigned IID = F->getIntrinsicID(); 1555 if (o == NumOperands-1) { 1556 BasicBlock &BB = *I->getParent(); 1557 1558 Module *M = BB.getParent()->getParent(); 1559 Type *ArgType = I->getType(); 1560 Type *VArgType = getVecTypeForPair(ArgType); 1561 1562 // FIXME: is it safe to do this here? 1563 ReplacedOperands[o] = Intrinsic::getDeclaration(M, 1564 (Intrinsic::ID) IID, VArgType); 1565 continue; 1566 } else if (IID == Intrinsic::powi && o == 1) { 1567 // The second argument of powi is a single integer and we've already 1568 // checked that both arguments are equal. As a result, we just keep 1569 // I's second argument. 1570 ReplacedOperands[o] = I->getOperand(o); 1571 continue; 1572 } 1573 } else if (isa<ShuffleVectorInst>(I) && o == NumOperands-1) { 1574 ReplacedOperands[o] = getReplacementShuffleMask(Context, I, J); 1575 continue; 1576 } 1577 1578 ReplacedOperands[o] = 1579 getReplacementInput(Context, I, J, o, FlipMemInputs); 1580 } 1581 } 1582 1583 // This function creates two values that represent the outputs of the 1584 // original I and J instructions. These are generally vector shuffles 1585 // or extracts. In many cases, these will end up being unused and, thus, 1586 // eliminated by later passes. 1587 void BBVectorize::replaceOutputsOfPair(LLVMContext& Context, Instruction *I, 1588 Instruction *J, Instruction *K, 1589 Instruction *&InsertionPt, 1590 Instruction *&K1, Instruction *&K2, 1591 bool &FlipMemInputs) { 1592 Value *CV0 = ConstantInt::get(Type::getInt32Ty(Context), 0); 1593 Value *CV1 = ConstantInt::get(Type::getInt32Ty(Context), 1); 1594 1595 if (isa<StoreInst>(I)) { 1596 AA->replaceWithNewValue(I, K); 1597 AA->replaceWithNewValue(J, K); 1598 } else { 1599 Type *IType = I->getType(); 1600 Type *VType = getVecTypeForPair(IType); 1601 1602 if (IType->isVectorTy()) { 1603 unsigned numElem = cast<VectorType>(IType)->getNumElements(); 1604 std::vector<Constant*> Mask1(numElem), Mask2(numElem); 1605 for (unsigned v = 0; v < numElem; ++v) { 1606 Mask1[v] = ConstantInt::get(Type::getInt32Ty(Context), v); 1607 Mask2[v] = ConstantInt::get(Type::getInt32Ty(Context), numElem+v); 1608 } 1609 1610 K1 = new ShuffleVectorInst(K, UndefValue::get(VType), 1611 ConstantVector::get( 1612 FlipMemInputs ? Mask2 : Mask1), 1613 getReplacementName(K, false, 1)); 1614 K2 = new ShuffleVectorInst(K, UndefValue::get(VType), 1615 ConstantVector::get( 1616 FlipMemInputs ? Mask1 : Mask2), 1617 getReplacementName(K, false, 2)); 1618 } else { 1619 K1 = ExtractElementInst::Create(K, FlipMemInputs ? CV1 : CV0, 1620 getReplacementName(K, false, 1)); 1621 K2 = ExtractElementInst::Create(K, FlipMemInputs ? CV0 : CV1, 1622 getReplacementName(K, false, 2)); 1623 } 1624 1625 K1->insertAfter(K); 1626 K2->insertAfter(K1); 1627 InsertionPt = K2; 1628 } 1629 } 1630 1631 // Move all uses of the function I (including pairing-induced uses) after J. 1632 bool BBVectorize::canMoveUsesOfIAfterJ(BasicBlock &BB, 1633 std::multimap<Value *, Value *> &LoadMoveSet, 1634 Instruction *I, Instruction *J) { 1635 // Skip to the first instruction past I. 1636 BasicBlock::iterator L = llvm::next(BasicBlock::iterator(I)); 1637 1638 DenseSet<Value *> Users; 1639 AliasSetTracker WriteSet(*AA); 1640 for (; cast<Instruction>(L) != J; ++L) 1641 (void) trackUsesOfI(Users, WriteSet, I, L, true, &LoadMoveSet); 1642 1643 assert(cast<Instruction>(L) == J && 1644 "Tracking has not proceeded far enough to check for dependencies"); 1645 // If J is now in the use set of I, then trackUsesOfI will return true 1646 // and we have a dependency cycle (and the fusing operation must abort). 1647 return !trackUsesOfI(Users, WriteSet, I, J, true, &LoadMoveSet); 1648 } 1649 1650 // Move all uses of the function I (including pairing-induced uses) after J. 1651 void BBVectorize::moveUsesOfIAfterJ(BasicBlock &BB, 1652 std::multimap<Value *, Value *> &LoadMoveSet, 1653 Instruction *&InsertionPt, 1654 Instruction *I, Instruction *J) { 1655 // Skip to the first instruction past I. 1656 BasicBlock::iterator L = llvm::next(BasicBlock::iterator(I)); 1657 1658 DenseSet<Value *> Users; 1659 AliasSetTracker WriteSet(*AA); 1660 for (; cast<Instruction>(L) != J;) { 1661 if (trackUsesOfI(Users, WriteSet, I, L, true, &LoadMoveSet)) { 1662 // Move this instruction 1663 Instruction *InstToMove = L; ++L; 1664 1665 DEBUG(dbgs() << "BBV: moving: " << *InstToMove << 1666 " to after " << *InsertionPt << "\n"); 1667 InstToMove->removeFromParent(); 1668 InstToMove->insertAfter(InsertionPt); 1669 InsertionPt = InstToMove; 1670 } else { 1671 ++L; 1672 } 1673 } 1674 } 1675 1676 // Collect all load instruction that are in the move set of a given first 1677 // pair member. These loads depend on the first instruction, I, and so need 1678 // to be moved after J (the second instruction) when the pair is fused. 1679 void BBVectorize::collectPairLoadMoveSet(BasicBlock &BB, 1680 DenseMap<Value *, Value *> &ChosenPairs, 1681 std::multimap<Value *, Value *> &LoadMoveSet, 1682 Instruction *I) { 1683 // Skip to the first instruction past I. 1684 BasicBlock::iterator L = llvm::next(BasicBlock::iterator(I)); 1685 1686 DenseSet<Value *> Users; 1687 AliasSetTracker WriteSet(*AA); 1688 1689 // Note: We cannot end the loop when we reach J because J could be moved 1690 // farther down the use chain by another instruction pairing. Also, J 1691 // could be before I if this is an inverted input. 1692 for (BasicBlock::iterator E = BB.end(); cast<Instruction>(L) != E; ++L) { 1693 if (trackUsesOfI(Users, WriteSet, I, L)) { 1694 if (L->mayReadFromMemory()) 1695 LoadMoveSet.insert(ValuePair(L, I)); 1696 } 1697 } 1698 } 1699 1700 // In cases where both load/stores and the computation of their pointers 1701 // are chosen for vectorization, we can end up in a situation where the 1702 // aliasing analysis starts returning different query results as the 1703 // process of fusing instruction pairs continues. Because the algorithm 1704 // relies on finding the same use trees here as were found earlier, we'll 1705 // need to precompute the necessary aliasing information here and then 1706 // manually update it during the fusion process. 1707 void BBVectorize::collectLoadMoveSet(BasicBlock &BB, 1708 std::vector<Value *> &PairableInsts, 1709 DenseMap<Value *, Value *> &ChosenPairs, 1710 std::multimap<Value *, Value *> &LoadMoveSet) { 1711 for (std::vector<Value *>::iterator PI = PairableInsts.begin(), 1712 PIE = PairableInsts.end(); PI != PIE; ++PI) { 1713 DenseMap<Value *, Value *>::iterator P = ChosenPairs.find(*PI); 1714 if (P == ChosenPairs.end()) continue; 1715 1716 Instruction *I = cast<Instruction>(P->first); 1717 collectPairLoadMoveSet(BB, ChosenPairs, LoadMoveSet, I); 1718 } 1719 } 1720 1721 // This function fuses the chosen instruction pairs into vector instructions, 1722 // taking care preserve any needed scalar outputs and, then, it reorders the 1723 // remaining instructions as needed (users of the first member of the pair 1724 // need to be moved to after the location of the second member of the pair 1725 // because the vector instruction is inserted in the location of the pair's 1726 // second member). 1727 void BBVectorize::fuseChosenPairs(BasicBlock &BB, 1728 std::vector<Value *> &PairableInsts, 1729 DenseMap<Value *, Value *> &ChosenPairs) { 1730 LLVMContext& Context = BB.getContext(); 1731 1732 // During the vectorization process, the order of the pairs to be fused 1733 // could be flipped. So we'll add each pair, flipped, into the ChosenPairs 1734 // list. After a pair is fused, the flipped pair is removed from the list. 1735 std::vector<ValuePair> FlippedPairs; 1736 FlippedPairs.reserve(ChosenPairs.size()); 1737 for (DenseMap<Value *, Value *>::iterator P = ChosenPairs.begin(), 1738 E = ChosenPairs.end(); P != E; ++P) 1739 FlippedPairs.push_back(ValuePair(P->second, P->first)); 1740 for (std::vector<ValuePair>::iterator P = FlippedPairs.begin(), 1741 E = FlippedPairs.end(); P != E; ++P) 1742 ChosenPairs.insert(*P); 1743 1744 std::multimap<Value *, Value *> LoadMoveSet; 1745 collectLoadMoveSet(BB, PairableInsts, ChosenPairs, LoadMoveSet); 1746 1747 DEBUG(dbgs() << "BBV: initial: \n" << BB << "\n"); 1748 1749 for (BasicBlock::iterator PI = BB.getFirstInsertionPt(); PI != BB.end();) { 1750 DenseMap<Value *, Value *>::iterator P = ChosenPairs.find(PI); 1751 if (P == ChosenPairs.end()) { 1752 ++PI; 1753 continue; 1754 } 1755 1756 if (getDepthFactor(P->first) == 0) { 1757 // These instructions are not really fused, but are tracked as though 1758 // they are. Any case in which it would be interesting to fuse them 1759 // will be taken care of by InstCombine. 1760 --NumFusedOps; 1761 ++PI; 1762 continue; 1763 } 1764 1765 Instruction *I = cast<Instruction>(P->first), 1766 *J = cast<Instruction>(P->second); 1767 1768 DEBUG(dbgs() << "BBV: fusing: " << *I << 1769 " <-> " << *J << "\n"); 1770 1771 // Remove the pair and flipped pair from the list. 1772 DenseMap<Value *, Value *>::iterator FP = ChosenPairs.find(P->second); 1773 assert(FP != ChosenPairs.end() && "Flipped pair not found in list"); 1774 ChosenPairs.erase(FP); 1775 ChosenPairs.erase(P); 1776 1777 if (!canMoveUsesOfIAfterJ(BB, LoadMoveSet, I, J)) { 1778 DEBUG(dbgs() << "BBV: fusion of: " << *I << 1779 " <-> " << *J << 1780 " aborted because of non-trivial dependency cycle\n"); 1781 --NumFusedOps; 1782 ++PI; 1783 continue; 1784 } 1785 1786 bool FlipMemInputs; 1787 unsigned NumOperands = I->getNumOperands(); 1788 SmallVector<Value *, 3> ReplacedOperands(NumOperands); 1789 getReplacementInputsForPair(Context, I, J, ReplacedOperands, 1790 FlipMemInputs); 1791 1792 // Make a copy of the original operation, change its type to the vector 1793 // type and replace its operands with the vector operands. 1794 Instruction *K = I->clone(); 1795 if (I->hasName()) K->takeName(I); 1796 1797 if (!isa<StoreInst>(K)) 1798 K->mutateType(getVecTypeForPair(I->getType())); 1799 1800 for (unsigned o = 0; o < NumOperands; ++o) 1801 K->setOperand(o, ReplacedOperands[o]); 1802 1803 // If we've flipped the memory inputs, make sure that we take the correct 1804 // alignment. 1805 if (FlipMemInputs) { 1806 if (isa<StoreInst>(K)) 1807 cast<StoreInst>(K)->setAlignment(cast<StoreInst>(J)->getAlignment()); 1808 else 1809 cast<LoadInst>(K)->setAlignment(cast<LoadInst>(J)->getAlignment()); 1810 } 1811 1812 K->insertAfter(J); 1813 1814 // Instruction insertion point: 1815 Instruction *InsertionPt = K; 1816 Instruction *K1 = 0, *K2 = 0; 1817 replaceOutputsOfPair(Context, I, J, K, InsertionPt, K1, K2, 1818 FlipMemInputs); 1819 1820 // The use tree of the first original instruction must be moved to after 1821 // the location of the second instruction. The entire use tree of the 1822 // first instruction is disjoint from the input tree of the second 1823 // (by definition), and so commutes with it. 1824 1825 moveUsesOfIAfterJ(BB, LoadMoveSet, InsertionPt, I, J); 1826 1827 if (!isa<StoreInst>(I)) { 1828 I->replaceAllUsesWith(K1); 1829 J->replaceAllUsesWith(K2); 1830 AA->replaceWithNewValue(I, K1); 1831 AA->replaceWithNewValue(J, K2); 1832 } 1833 1834 // Instructions that may read from memory may be in the load move set. 1835 // Once an instruction is fused, we no longer need its move set, and so 1836 // the values of the map never need to be updated. However, when a load 1837 // is fused, we need to merge the entries from both instructions in the 1838 // pair in case those instructions were in the move set of some other 1839 // yet-to-be-fused pair. The loads in question are the keys of the map. 1840 if (I->mayReadFromMemory()) { 1841 std::vector<ValuePair> NewSetMembers; 1842 VPIteratorPair IPairRange = LoadMoveSet.equal_range(I); 1843 VPIteratorPair JPairRange = LoadMoveSet.equal_range(J); 1844 for (std::multimap<Value *, Value *>::iterator N = IPairRange.first; 1845 N != IPairRange.second; ++N) 1846 NewSetMembers.push_back(ValuePair(K, N->second)); 1847 for (std::multimap<Value *, Value *>::iterator N = JPairRange.first; 1848 N != JPairRange.second; ++N) 1849 NewSetMembers.push_back(ValuePair(K, N->second)); 1850 for (std::vector<ValuePair>::iterator A = NewSetMembers.begin(), 1851 AE = NewSetMembers.end(); A != AE; ++A) 1852 LoadMoveSet.insert(*A); 1853 } 1854 1855 // Before removing I, set the iterator to the next instruction. 1856 PI = llvm::next(BasicBlock::iterator(I)); 1857 if (cast<Instruction>(PI) == J) 1858 ++PI; 1859 1860 SE->forgetValue(I); 1861 SE->forgetValue(J); 1862 I->eraseFromParent(); 1863 J->eraseFromParent(); 1864 } 1865 1866 DEBUG(dbgs() << "BBV: final: \n" << BB << "\n"); 1867 } 1868} 1869 1870char BBVectorize::ID = 0; 1871static const char bb_vectorize_name[] = "Basic-Block Vectorization"; 1872INITIALIZE_PASS_BEGIN(BBVectorize, BBV_NAME, bb_vectorize_name, false, false) 1873INITIALIZE_AG_DEPENDENCY(AliasAnalysis) 1874INITIALIZE_PASS_DEPENDENCY(ScalarEvolution) 1875INITIALIZE_PASS_END(BBVectorize, BBV_NAME, bb_vectorize_name, false, false) 1876 1877BasicBlockPass *llvm::createBBVectorizePass(const VectorizeConfig &C) { 1878 return new BBVectorize(C); 1879} 1880 1881bool 1882llvm::vectorizeBasicBlock(Pass *P, BasicBlock &BB, const VectorizeConfig &C) { 1883 BBVectorize BBVectorizer(P, C); 1884 return BBVectorizer.vectorizeBB(BB); 1885} 1886 1887//===----------------------------------------------------------------------===// 1888VectorizeConfig::VectorizeConfig() { 1889 VectorBits = ::VectorBits; 1890 NoInts = ::NoInts; 1891 NoFloats = ::NoFloats; 1892 NoCasts = ::NoCasts; 1893 NoMath = ::NoMath; 1894 NoFMA = ::NoFMA; 1895 NoMemOps = ::NoMemOps; 1896 AlignedOnly = ::AlignedOnly; 1897 ReqChainDepth= ::ReqChainDepth; 1898 SearchLimit = ::SearchLimit; 1899 MaxCandPairsForCycleCheck = ::MaxCandPairsForCycleCheck; 1900 SplatBreaksChain = ::SplatBreaksChain; 1901 MaxInsts = ::MaxInsts; 1902 MaxIter = ::MaxIter; 1903 NoMemOpBoost = ::NoMemOpBoost; 1904 FastDep = ::FastDep; 1905} 1906