LLVM  7.0.0svn
MemCpyOptimizer.cpp
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1 //===- MemCpyOptimizer.cpp - Optimize use of memcpy and friends -----------===//
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 performs various transformations related to eliminating memcpy
11 // calls, or transforming sets of stores into memset's.
12 //
13 //===----------------------------------------------------------------------===//
14 
16 #include "llvm/ADT/DenseSet.h"
17 #include "llvm/ADT/None.h"
18 #include "llvm/ADT/STLExtras.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/ADT/Statistic.h"
30 #include "llvm/IR/Argument.h"
31 #include "llvm/IR/BasicBlock.h"
32 #include "llvm/IR/CallSite.h"
33 #include "llvm/IR/Constants.h"
34 #include "llvm/IR/DataLayout.h"
35 #include "llvm/IR/DerivedTypes.h"
36 #include "llvm/IR/Dominators.h"
37 #include "llvm/IR/Function.h"
39 #include "llvm/IR/GlobalVariable.h"
40 #include "llvm/IR/IRBuilder.h"
41 #include "llvm/IR/InstrTypes.h"
42 #include "llvm/IR/Instruction.h"
43 #include "llvm/IR/Instructions.h"
44 #include "llvm/IR/IntrinsicInst.h"
45 #include "llvm/IR/Intrinsics.h"
46 #include "llvm/IR/LLVMContext.h"
47 #include "llvm/IR/Module.h"
48 #include "llvm/IR/Operator.h"
49 #include "llvm/IR/PassManager.h"
50 #include "llvm/IR/Type.h"
51 #include "llvm/IR/User.h"
52 #include "llvm/IR/Value.h"
53 #include "llvm/Pass.h"
54 #include "llvm/Support/Casting.h"
55 #include "llvm/Support/Debug.h"
58 #include "llvm/Transforms/Scalar.h"
59 #include <algorithm>
60 #include <cassert>
61 #include <cstdint>
62 #include <utility>
63 
64 using namespace llvm;
65 
66 #define DEBUG_TYPE "memcpyopt"
67 
68 STATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted");
69 STATISTIC(NumMemSetInfer, "Number of memsets inferred");
70 STATISTIC(NumMoveToCpy, "Number of memmoves converted to memcpy");
71 STATISTIC(NumCpyToSet, "Number of memcpys converted to memset");
72 
73 static int64_t GetOffsetFromIndex(const GEPOperator *GEP, unsigned Idx,
74  bool &VariableIdxFound,
75  const DataLayout &DL) {
76  // Skip over the first indices.
78  for (unsigned i = 1; i != Idx; ++i, ++GTI)
79  /*skip along*/;
80 
81  // Compute the offset implied by the rest of the indices.
82  int64_t Offset = 0;
83  for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
84  ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i));
85  if (!OpC)
86  return VariableIdxFound = true;
87  if (OpC->isZero()) continue; // No offset.
88 
89  // Handle struct indices, which add their field offset to the pointer.
90  if (StructType *STy = GTI.getStructTypeOrNull()) {
91  Offset += DL.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
92  continue;
93  }
94 
95  // Otherwise, we have a sequential type like an array or vector. Multiply
96  // the index by the ElementSize.
97  uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType());
98  Offset += Size*OpC->getSExtValue();
99  }
100 
101  return Offset;
102 }
103 
104 /// Return true if Ptr1 is provably equal to Ptr2 plus a constant offset, and
105 /// return that constant offset. For example, Ptr1 might be &A[42], and Ptr2
106 /// might be &A[40]. In this case offset would be -8.
107 static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset,
108  const DataLayout &DL) {
109  Ptr1 = Ptr1->stripPointerCasts();
110  Ptr2 = Ptr2->stripPointerCasts();
111 
112  // Handle the trivial case first.
113  if (Ptr1 == Ptr2) {
114  Offset = 0;
115  return true;
116  }
117 
118  GEPOperator *GEP1 = dyn_cast<GEPOperator>(Ptr1);
119  GEPOperator *GEP2 = dyn_cast<GEPOperator>(Ptr2);
120 
121  bool VariableIdxFound = false;
122 
123  // If one pointer is a GEP and the other isn't, then see if the GEP is a
124  // constant offset from the base, as in "P" and "gep P, 1".
125  if (GEP1 && !GEP2 && GEP1->getOperand(0)->stripPointerCasts() == Ptr2) {
126  Offset = -GetOffsetFromIndex(GEP1, 1, VariableIdxFound, DL);
127  return !VariableIdxFound;
128  }
129 
130  if (GEP2 && !GEP1 && GEP2->getOperand(0)->stripPointerCasts() == Ptr1) {
131  Offset = GetOffsetFromIndex(GEP2, 1, VariableIdxFound, DL);
132  return !VariableIdxFound;
133  }
134 
135  // Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical
136  // base. After that base, they may have some number of common (and
137  // potentially variable) indices. After that they handle some constant
138  // offset, which determines their offset from each other. At this point, we
139  // handle no other case.
140  if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0))
141  return false;
142 
143  // Skip any common indices and track the GEP types.
144  unsigned Idx = 1;
145  for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx)
146  if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx))
147  break;
148 
149  int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, DL);
150  int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, DL);
151  if (VariableIdxFound) return false;
152 
153  Offset = Offset2-Offset1;
154  return true;
155 }
156 
157 namespace {
158 
159 /// Represents a range of memset'd bytes with the ByteVal value.
160 /// This allows us to analyze stores like:
161 /// store 0 -> P+1
162 /// store 0 -> P+0
163 /// store 0 -> P+3
164 /// store 0 -> P+2
165 /// which sometimes happens with stores to arrays of structs etc. When we see
166 /// the first store, we make a range [1, 2). The second store extends the range
167 /// to [0, 2). The third makes a new range [2, 3). The fourth store joins the
168 /// two ranges into [0, 3) which is memset'able.
169 struct MemsetRange {
170  // Start/End - A semi range that describes the span that this range covers.
171  // The range is closed at the start and open at the end: [Start, End).
172  int64_t Start, End;
173 
174  /// StartPtr - The getelementptr instruction that points to the start of the
175  /// range.
176  Value *StartPtr;
177 
178  /// Alignment - The known alignment of the first store.
179  unsigned Alignment;
180 
181  /// TheStores - The actual stores that make up this range.
183 
184  bool isProfitableToUseMemset(const DataLayout &DL) const;
185 };
186 
187 } // end anonymous namespace
188 
189 bool MemsetRange::isProfitableToUseMemset(const DataLayout &DL) const {
190  // If we found more than 4 stores to merge or 16 bytes, use memset.
191  if (TheStores.size() >= 4 || End-Start >= 16) return true;
192 
193  // If there is nothing to merge, don't do anything.
194  if (TheStores.size() < 2) return false;
195 
196  // If any of the stores are a memset, then it is always good to extend the
197  // memset.
198  for (Instruction *SI : TheStores)
199  if (!isa<StoreInst>(SI))
200  return true;
201 
202  // Assume that the code generator is capable of merging pairs of stores
203  // together if it wants to.
204  if (TheStores.size() == 2) return false;
205 
206  // If we have fewer than 8 stores, it can still be worthwhile to do this.
207  // For example, merging 4 i8 stores into an i32 store is useful almost always.
208  // However, merging 2 32-bit stores isn't useful on a 32-bit architecture (the
209  // memset will be split into 2 32-bit stores anyway) and doing so can
210  // pessimize the llvm optimizer.
211  //
212  // Since we don't have perfect knowledge here, make some assumptions: assume
213  // the maximum GPR width is the same size as the largest legal integer
214  // size. If so, check to see whether we will end up actually reducing the
215  // number of stores used.
216  unsigned Bytes = unsigned(End-Start);
217  unsigned MaxIntSize = DL.getLargestLegalIntTypeSizeInBits() / 8;
218  if (MaxIntSize == 0)
219  MaxIntSize = 1;
220  unsigned NumPointerStores = Bytes / MaxIntSize;
221 
222  // Assume the remaining bytes if any are done a byte at a time.
223  unsigned NumByteStores = Bytes % MaxIntSize;
224 
225  // If we will reduce the # stores (according to this heuristic), do the
226  // transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32
227  // etc.
228  return TheStores.size() > NumPointerStores+NumByteStores;
229 }
230 
231 namespace {
232 
233 class MemsetRanges {
234  using range_iterator = SmallVectorImpl<MemsetRange>::iterator;
235 
236  /// A sorted list of the memset ranges.
238 
239  const DataLayout &DL;
240 
241 public:
242  MemsetRanges(const DataLayout &DL) : DL(DL) {}
243 
244  using const_iterator = SmallVectorImpl<MemsetRange>::const_iterator;
245 
246  const_iterator begin() const { return Ranges.begin(); }
247  const_iterator end() const { return Ranges.end(); }
248  bool empty() const { return Ranges.empty(); }
249 
250  void addInst(int64_t OffsetFromFirst, Instruction *Inst) {
251  if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
252  addStore(OffsetFromFirst, SI);
253  else
254  addMemSet(OffsetFromFirst, cast<MemSetInst>(Inst));
255  }
256 
257  void addStore(int64_t OffsetFromFirst, StoreInst *SI) {
258  int64_t StoreSize = DL.getTypeStoreSize(SI->getOperand(0)->getType());
259 
260  addRange(OffsetFromFirst, StoreSize,
261  SI->getPointerOperand(), SI->getAlignment(), SI);
262  }
263 
264  void addMemSet(int64_t OffsetFromFirst, MemSetInst *MSI) {
265  int64_t Size = cast<ConstantInt>(MSI->getLength())->getZExtValue();
266  addRange(OffsetFromFirst, Size, MSI->getDest(), MSI->getDestAlignment(), MSI);
267  }
268 
269  void addRange(int64_t Start, int64_t Size, Value *Ptr,
270  unsigned Alignment, Instruction *Inst);
271 };
272 
273 } // end anonymous namespace
274 
275 /// Add a new store to the MemsetRanges data structure. This adds a
276 /// new range for the specified store at the specified offset, merging into
277 /// existing ranges as appropriate.
278 void MemsetRanges::addRange(int64_t Start, int64_t Size, Value *Ptr,
279  unsigned Alignment, Instruction *Inst) {
280  int64_t End = Start+Size;
281 
282  range_iterator I = std::lower_bound(Ranges.begin(), Ranges.end(), Start,
283  [](const MemsetRange &LHS, int64_t RHS) { return LHS.End < RHS; });
284 
285  // We now know that I == E, in which case we didn't find anything to merge
286  // with, or that Start <= I->End. If End < I->Start or I == E, then we need
287  // to insert a new range. Handle this now.
288  if (I == Ranges.end() || End < I->Start) {
289  MemsetRange &R = *Ranges.insert(I, MemsetRange());
290  R.Start = Start;
291  R.End = End;
292  R.StartPtr = Ptr;
293  R.Alignment = Alignment;
294  R.TheStores.push_back(Inst);
295  return;
296  }
297 
298  // This store overlaps with I, add it.
299  I->TheStores.push_back(Inst);
300 
301  // At this point, we may have an interval that completely contains our store.
302  // If so, just add it to the interval and return.
303  if (I->Start <= Start && I->End >= End)
304  return;
305 
306  // Now we know that Start <= I->End and End >= I->Start so the range overlaps
307  // but is not entirely contained within the range.
308 
309  // See if the range extends the start of the range. In this case, it couldn't
310  // possibly cause it to join the prior range, because otherwise we would have
311  // stopped on *it*.
312  if (Start < I->Start) {
313  I->Start = Start;
314  I->StartPtr = Ptr;
315  I->Alignment = Alignment;
316  }
317 
318  // Now we know that Start <= I->End and Start >= I->Start (so the startpoint
319  // is in or right at the end of I), and that End >= I->Start. Extend I out to
320  // End.
321  if (End > I->End) {
322  I->End = End;
323  range_iterator NextI = I;
324  while (++NextI != Ranges.end() && End >= NextI->Start) {
325  // Merge the range in.
326  I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end());
327  if (NextI->End > I->End)
328  I->End = NextI->End;
329  Ranges.erase(NextI);
330  NextI = I;
331  }
332  }
333 }
334 
335 //===----------------------------------------------------------------------===//
336 // MemCpyOptLegacyPass Pass
337 //===----------------------------------------------------------------------===//
338 
339 namespace {
340 
341 class MemCpyOptLegacyPass : public FunctionPass {
342  MemCpyOptPass Impl;
343 
344 public:
345  static char ID; // Pass identification, replacement for typeid
346 
347  MemCpyOptLegacyPass() : FunctionPass(ID) {
349  }
350 
351  bool runOnFunction(Function &F) override;
352 
353 private:
354  // This transformation requires dominator postdominator info
355  void getAnalysisUsage(AnalysisUsage &AU) const override {
356  AU.setPreservesCFG();
364  }
365 };
366 
367 } // end anonymous namespace
368 
369 char MemCpyOptLegacyPass::ID = 0;
370 
371 /// The public interface to this file...
372 FunctionPass *llvm::createMemCpyOptPass() { return new MemCpyOptLegacyPass(); }
373 
374 INITIALIZE_PASS_BEGIN(MemCpyOptLegacyPass, "memcpyopt", "MemCpy Optimization",
375  false, false)
382 INITIALIZE_PASS_END(MemCpyOptLegacyPass, "memcpyopt", "MemCpy Optimization",
383  false, false)
384 
385 /// When scanning forward over instructions, we look for some other patterns to
386 /// fold away. In particular, this looks for stores to neighboring locations of
387 /// memory. If it sees enough consecutive ones, it attempts to merge them
388 /// together into a memcpy/memset.
389 Instruction *MemCpyOptPass::tryMergingIntoMemset(Instruction *StartInst,
390  Value *StartPtr,
391  Value *ByteVal) {
392  const DataLayout &DL = StartInst->getModule()->getDataLayout();
393 
394  // Okay, so we now have a single store that can be splatable. Scan to find
395  // all subsequent stores of the same value to offset from the same pointer.
396  // Join these together into ranges, so we can decide whether contiguous blocks
397  // are stored.
398  MemsetRanges Ranges(DL);
399 
400  BasicBlock::iterator BI(StartInst);
401  for (++BI; !isa<TerminatorInst>(BI); ++BI) {
402  if (!isa<StoreInst>(BI) && !isa<MemSetInst>(BI)) {
403  // If the instruction is readnone, ignore it, otherwise bail out. We
404  // don't even allow readonly here because we don't want something like:
405  // A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A).
406  if (BI->mayWriteToMemory() || BI->mayReadFromMemory())
407  break;
408  continue;
409  }
410 
411  if (StoreInst *NextStore = dyn_cast<StoreInst>(BI)) {
412  // If this is a store, see if we can merge it in.
413  if (!NextStore->isSimple()) break;
414 
415  // Check to see if this stored value is of the same byte-splattable value.
416  if (ByteVal != isBytewiseValue(NextStore->getOperand(0)))
417  break;
418 
419  // Check to see if this store is to a constant offset from the start ptr.
420  int64_t Offset;
421  if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset,
422  DL))
423  break;
424 
425  Ranges.addStore(Offset, NextStore);
426  } else {
427  MemSetInst *MSI = cast<MemSetInst>(BI);
428 
429  if (MSI->isVolatile() || ByteVal != MSI->getValue() ||
430  !isa<ConstantInt>(MSI->getLength()))
431  break;
432 
433  // Check to see if this store is to a constant offset from the start ptr.
434  int64_t Offset;
435  if (!IsPointerOffset(StartPtr, MSI->getDest(), Offset, DL))
436  break;
437 
438  Ranges.addMemSet(Offset, MSI);
439  }
440  }
441 
442  // If we have no ranges, then we just had a single store with nothing that
443  // could be merged in. This is a very common case of course.
444  if (Ranges.empty())
445  return nullptr;
446 
447  // If we had at least one store that could be merged in, add the starting
448  // store as well. We try to avoid this unless there is at least something
449  // interesting as a small compile-time optimization.
450  Ranges.addInst(0, StartInst);
451 
452  // If we create any memsets, we put it right before the first instruction that
453  // isn't part of the memset block. This ensure that the memset is dominated
454  // by any addressing instruction needed by the start of the block.
455  IRBuilder<> Builder(&*BI);
456 
457  // Now that we have full information about ranges, loop over the ranges and
458  // emit memset's for anything big enough to be worthwhile.
459  Instruction *AMemSet = nullptr;
460  for (const MemsetRange &Range : Ranges) {
461  if (Range.TheStores.size() == 1) continue;
462 
463  // If it is profitable to lower this range to memset, do so now.
464  if (!Range.isProfitableToUseMemset(DL))
465  continue;
466 
467  // Otherwise, we do want to transform this! Create a new memset.
468  // Get the starting pointer of the block.
469  StartPtr = Range.StartPtr;
470 
471  // Determine alignment
472  unsigned Alignment = Range.Alignment;
473  if (Alignment == 0) {
474  Type *EltType =
475  cast<PointerType>(StartPtr->getType())->getElementType();
476  Alignment = DL.getABITypeAlignment(EltType);
477  }
478 
479  AMemSet =
480  Builder.CreateMemSet(StartPtr, ByteVal, Range.End-Range.Start, Alignment);
481 
482  LLVM_DEBUG(dbgs() << "Replace stores:\n"; for (Instruction *SI
483  : Range.TheStores) dbgs()
484  << *SI << '\n';
485  dbgs() << "With: " << *AMemSet << '\n');
486 
487  if (!Range.TheStores.empty())
488  AMemSet->setDebugLoc(Range.TheStores[0]->getDebugLoc());
489 
490  // Zap all the stores.
491  for (Instruction *SI : Range.TheStores) {
492  MD->removeInstruction(SI);
493  SI->eraseFromParent();
494  }
495  ++NumMemSetInfer;
496  }
497 
498  return AMemSet;
499 }
500 
501 static unsigned findStoreAlignment(const DataLayout &DL, const StoreInst *SI) {
502  unsigned StoreAlign = SI->getAlignment();
503  if (!StoreAlign)
504  StoreAlign = DL.getABITypeAlignment(SI->getOperand(0)->getType());
505  return StoreAlign;
506 }
507 
508 static unsigned findLoadAlignment(const DataLayout &DL, const LoadInst *LI) {
509  unsigned LoadAlign = LI->getAlignment();
510  if (!LoadAlign)
511  LoadAlign = DL.getABITypeAlignment(LI->getType());
512  return LoadAlign;
513 }
514 
515 static unsigned findCommonAlignment(const DataLayout &DL, const StoreInst *SI,
516  const LoadInst *LI) {
517  unsigned StoreAlign = findStoreAlignment(DL, SI);
518  unsigned LoadAlign = findLoadAlignment(DL, LI);
519  return MinAlign(StoreAlign, LoadAlign);
520 }
521 
522 // This method try to lift a store instruction before position P.
523 // It will lift the store and its argument + that anything that
524 // may alias with these.
525 // The method returns true if it was successful.
527  const LoadInst *LI) {
528  // If the store alias this position, early bail out.
529  MemoryLocation StoreLoc = MemoryLocation::get(SI);
530  if (isModOrRefSet(AA.getModRefInfo(P, StoreLoc)))
531  return false;
532 
533  // Keep track of the arguments of all instruction we plan to lift
534  // so we can make sure to lift them as well if appropriate.
536  if (auto *Ptr = dyn_cast<Instruction>(SI->getPointerOperand()))
537  if (Ptr->getParent() == SI->getParent())
538  Args.insert(Ptr);
539 
540  // Instruction to lift before P.
542 
543  // Memory locations of lifted instructions.
544  SmallVector<MemoryLocation, 8> MemLocs{StoreLoc};
545 
546  // Lifted callsites.
548 
549  const MemoryLocation LoadLoc = MemoryLocation::get(LI);
550 
551  for (auto I = --SI->getIterator(), E = P->getIterator(); I != E; --I) {
552  auto *C = &*I;
553 
555 
556  bool NeedLift = false;
557  if (Args.erase(C))
558  NeedLift = true;
559  else if (MayAlias) {
560  NeedLift = llvm::any_of(MemLocs, [C, &AA](const MemoryLocation &ML) {
561  return isModOrRefSet(AA.getModRefInfo(C, ML));
562  });
563 
564  if (!NeedLift)
565  NeedLift =
566  llvm::any_of(CallSites, [C, &AA](const ImmutableCallSite &CS) {
567  return isModOrRefSet(AA.getModRefInfo(C, CS));
568  });
569  }
570 
571  if (!NeedLift)
572  continue;
573 
574  if (MayAlias) {
575  // Since LI is implicitly moved downwards past the lifted instructions,
576  // none of them may modify its source.
577  if (isModSet(AA.getModRefInfo(C, LoadLoc)))
578  return false;
579  else if (auto CS = ImmutableCallSite(C)) {
580  // If we can't lift this before P, it's game over.
581  if (isModOrRefSet(AA.getModRefInfo(P, CS)))
582  return false;
583 
584  CallSites.push_back(CS);
585  } else if (isa<LoadInst>(C) || isa<StoreInst>(C) || isa<VAArgInst>(C)) {
586  // If we can't lift this before P, it's game over.
587  auto ML = MemoryLocation::get(C);
588  if (isModOrRefSet(AA.getModRefInfo(P, ML)))
589  return false;
590 
591  MemLocs.push_back(ML);
592  } else
593  // We don't know how to lift this instruction.
594  return false;
595  }
596 
597  ToLift.push_back(C);
598  for (unsigned k = 0, e = C->getNumOperands(); k != e; ++k)
599  if (auto *A = dyn_cast<Instruction>(C->getOperand(k)))
600  if (A->getParent() == SI->getParent())
601  Args.insert(A);
602  }
603 
604  // We made it, we need to lift
605  for (auto *I : llvm::reverse(ToLift)) {
606  LLVM_DEBUG(dbgs() << "Lifting " << *I << " before " << *P << "\n");
607  I->moveBefore(P);
608  }
609 
610  return true;
611 }
612 
613 bool MemCpyOptPass::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
614  if (!SI->isSimple()) return false;
615 
616  // Avoid merging nontemporal stores since the resulting
617  // memcpy/memset would not be able to preserve the nontemporal hint.
618  // In theory we could teach how to propagate the !nontemporal metadata to
619  // memset calls. However, that change would force the backend to
620  // conservatively expand !nontemporal memset calls back to sequences of
621  // store instructions (effectively undoing the merging).
623  return false;
624 
625  const DataLayout &DL = SI->getModule()->getDataLayout();
626 
627  // Load to store forwarding can be interpreted as memcpy.
628  if (LoadInst *LI = dyn_cast<LoadInst>(SI->getOperand(0))) {
629  if (LI->isSimple() && LI->hasOneUse() &&
630  LI->getParent() == SI->getParent()) {
631 
632  auto *T = LI->getType();
633  if (T->isAggregateType()) {
634  AliasAnalysis &AA = LookupAliasAnalysis();
635  MemoryLocation LoadLoc = MemoryLocation::get(LI);
636 
637  // We use alias analysis to check if an instruction may store to
638  // the memory we load from in between the load and the store. If
639  // such an instruction is found, we try to promote there instead
640  // of at the store position.
641  Instruction *P = SI;
642  for (auto &I : make_range(++LI->getIterator(), SI->getIterator())) {
643  if (isModSet(AA.getModRefInfo(&I, LoadLoc))) {
644  P = &I;
645  break;
646  }
647  }
648 
649  // We found an instruction that may write to the loaded memory.
650  // We can try to promote at this position instead of the store
651  // position if nothing alias the store memory after this and the store
652  // destination is not in the range.
653  if (P && P != SI) {
654  if (!moveUp(AA, SI, P, LI))
655  P = nullptr;
656  }
657 
658  // If a valid insertion position is found, then we can promote
659  // the load/store pair to a memcpy.
660  if (P) {
661  // If we load from memory that may alias the memory we store to,
662  // memmove must be used to preserve semantic. If not, memcpy can
663  // be used.
664  bool UseMemMove = false;
665  if (!AA.isNoAlias(MemoryLocation::get(SI), LoadLoc))
666  UseMemMove = true;
667 
668  uint64_t Size = DL.getTypeStoreSize(T);
669 
670  IRBuilder<> Builder(P);
671  Instruction *M;
672  if (UseMemMove)
673  M = Builder.CreateMemMove(
674  SI->getPointerOperand(), findStoreAlignment(DL, SI),
675  LI->getPointerOperand(), findLoadAlignment(DL, LI), Size,
676  SI->isVolatile());
677  else
678  M = Builder.CreateMemCpy(
679  SI->getPointerOperand(), findStoreAlignment(DL, SI),
680  LI->getPointerOperand(), findLoadAlignment(DL, LI), Size,
681  SI->isVolatile());
682 
683  LLVM_DEBUG(dbgs() << "Promoting " << *LI << " to " << *SI << " => "
684  << *M << "\n");
685 
686  MD->removeInstruction(SI);
687  SI->eraseFromParent();
688  MD->removeInstruction(LI);
689  LI->eraseFromParent();
690  ++NumMemCpyInstr;
691 
692  // Make sure we do not invalidate the iterator.
693  BBI = M->getIterator();
694  return true;
695  }
696  }
697 
698  // Detect cases where we're performing call slot forwarding, but
699  // happen to be using a load-store pair to implement it, rather than
700  // a memcpy.
701  MemDepResult ldep = MD->getDependency(LI);
702  CallInst *C = nullptr;
703  if (ldep.isClobber() && !isa<MemCpyInst>(ldep.getInst()))
704  C = dyn_cast<CallInst>(ldep.getInst());
705 
706  if (C) {
707  // Check that nothing touches the dest of the "copy" between
708  // the call and the store.
709  Value *CpyDest = SI->getPointerOperand()->stripPointerCasts();
710  bool CpyDestIsLocal = isa<AllocaInst>(CpyDest);
711  AliasAnalysis &AA = LookupAliasAnalysis();
712  MemoryLocation StoreLoc = MemoryLocation::get(SI);
713  for (BasicBlock::iterator I = --SI->getIterator(), E = C->getIterator();
714  I != E; --I) {
715  if (isModOrRefSet(AA.getModRefInfo(&*I, StoreLoc))) {
716  C = nullptr;
717  break;
718  }
719  // The store to dest may never happen if an exception can be thrown
720  // between the load and the store.
721  if (I->mayThrow() && !CpyDestIsLocal) {
722  C = nullptr;
723  break;
724  }
725  }
726  }
727 
728  if (C) {
729  bool changed = performCallSlotOptzn(
731  LI->getPointerOperand()->stripPointerCasts(),
732  DL.getTypeStoreSize(SI->getOperand(0)->getType()),
733  findCommonAlignment(DL, SI, LI), C);
734  if (changed) {
735  MD->removeInstruction(SI);
736  SI->eraseFromParent();
737  MD->removeInstruction(LI);
738  LI->eraseFromParent();
739  ++NumMemCpyInstr;
740  return true;
741  }
742  }
743  }
744  }
745 
746  // There are two cases that are interesting for this code to handle: memcpy
747  // and memset. Right now we only handle memset.
748 
749  // Ensure that the value being stored is something that can be memset'able a
750  // byte at a time like "0" or "-1" or any width, as well as things like
751  // 0xA0A0A0A0 and 0.0.
752  auto *V = SI->getOperand(0);
753  if (Value *ByteVal = isBytewiseValue(V)) {
754  if (Instruction *I = tryMergingIntoMemset(SI, SI->getPointerOperand(),
755  ByteVal)) {
756  BBI = I->getIterator(); // Don't invalidate iterator.
757  return true;
758  }
759 
760  // If we have an aggregate, we try to promote it to memset regardless
761  // of opportunity for merging as it can expose optimization opportunities
762  // in subsequent passes.
763  auto *T = V->getType();
764  if (T->isAggregateType()) {
765  uint64_t Size = DL.getTypeStoreSize(T);
766  unsigned Align = SI->getAlignment();
767  if (!Align)
768  Align = DL.getABITypeAlignment(T);
769  IRBuilder<> Builder(SI);
770  auto *M = Builder.CreateMemSet(SI->getPointerOperand(), ByteVal,
771  Size, Align, SI->isVolatile());
772 
773  LLVM_DEBUG(dbgs() << "Promoting " << *SI << " to " << *M << "\n");
774 
775  MD->removeInstruction(SI);
776  SI->eraseFromParent();
777  NumMemSetInfer++;
778 
779  // Make sure we do not invalidate the iterator.
780  BBI = M->getIterator();
781  return true;
782  }
783  }
784 
785  return false;
786 }
787 
788 bool MemCpyOptPass::processMemSet(MemSetInst *MSI, BasicBlock::iterator &BBI) {
789  // See if there is another memset or store neighboring this memset which
790  // allows us to widen out the memset to do a single larger store.
791  if (isa<ConstantInt>(MSI->getLength()) && !MSI->isVolatile())
792  if (Instruction *I = tryMergingIntoMemset(MSI, MSI->getDest(),
793  MSI->getValue())) {
794  BBI = I->getIterator(); // Don't invalidate iterator.
795  return true;
796  }
797  return false;
798 }
799 
800 /// Takes a memcpy and a call that it depends on,
801 /// and checks for the possibility of a call slot optimization by having
802 /// the call write its result directly into the destination of the memcpy.
803 bool MemCpyOptPass::performCallSlotOptzn(Instruction *cpy, Value *cpyDest,
804  Value *cpySrc, uint64_t cpyLen,
805  unsigned cpyAlign, CallInst *C) {
806  // The general transformation to keep in mind is
807  //
808  // call @func(..., src, ...)
809  // memcpy(dest, src, ...)
810  //
811  // ->
812  //
813  // memcpy(dest, src, ...)
814  // call @func(..., dest, ...)
815  //
816  // Since moving the memcpy is technically awkward, we additionally check that
817  // src only holds uninitialized values at the moment of the call, meaning that
818  // the memcpy can be discarded rather than moved.
819 
820  // Lifetime marks shouldn't be operated on.
821  if (Function *F = C->getCalledFunction())
822  if (F->isIntrinsic() && F->getIntrinsicID() == Intrinsic::lifetime_start)
823  return false;
824 
825  // Deliberately get the source and destination with bitcasts stripped away,
826  // because we'll need to do type comparisons based on the underlying type.
827  CallSite CS(C);
828 
829  // Require that src be an alloca. This simplifies the reasoning considerably.
830  AllocaInst *srcAlloca = dyn_cast<AllocaInst>(cpySrc);
831  if (!srcAlloca)
832  return false;
833 
834  ConstantInt *srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize());
835  if (!srcArraySize)
836  return false;
837 
838  const DataLayout &DL = cpy->getModule()->getDataLayout();
839  uint64_t srcSize = DL.getTypeAllocSize(srcAlloca->getAllocatedType()) *
840  srcArraySize->getZExtValue();
841 
842  if (cpyLen < srcSize)
843  return false;
844 
845  // Check that accessing the first srcSize bytes of dest will not cause a
846  // trap. Otherwise the transform is invalid since it might cause a trap
847  // to occur earlier than it otherwise would.
848  if (AllocaInst *A = dyn_cast<AllocaInst>(cpyDest)) {
849  // The destination is an alloca. Check it is larger than srcSize.
850  ConstantInt *destArraySize = dyn_cast<ConstantInt>(A->getArraySize());
851  if (!destArraySize)
852  return false;
853 
854  uint64_t destSize = DL.getTypeAllocSize(A->getAllocatedType()) *
855  destArraySize->getZExtValue();
856 
857  if (destSize < srcSize)
858  return false;
859  } else if (Argument *A = dyn_cast<Argument>(cpyDest)) {
860  // The store to dest may never happen if the call can throw.
861  if (C->mayThrow())
862  return false;
863 
864  if (A->getDereferenceableBytes() < srcSize) {
865  // If the destination is an sret parameter then only accesses that are
866  // outside of the returned struct type can trap.
867  if (!A->hasStructRetAttr())
868  return false;
869 
870  Type *StructTy = cast<PointerType>(A->getType())->getElementType();
871  if (!StructTy->isSized()) {
872  // The call may never return and hence the copy-instruction may never
873  // be executed, and therefore it's not safe to say "the destination
874  // has at least <cpyLen> bytes, as implied by the copy-instruction",
875  return false;
876  }
877 
878  uint64_t destSize = DL.getTypeAllocSize(StructTy);
879  if (destSize < srcSize)
880  return false;
881  }
882  } else {
883  return false;
884  }
885 
886  // Check that dest points to memory that is at least as aligned as src.
887  unsigned srcAlign = srcAlloca->getAlignment();
888  if (!srcAlign)
889  srcAlign = DL.getABITypeAlignment(srcAlloca->getAllocatedType());
890  bool isDestSufficientlyAligned = srcAlign <= cpyAlign;
891  // If dest is not aligned enough and we can't increase its alignment then
892  // bail out.
893  if (!isDestSufficientlyAligned && !isa<AllocaInst>(cpyDest))
894  return false;
895 
896  // Check that src is not accessed except via the call and the memcpy. This
897  // guarantees that it holds only undefined values when passed in (so the final
898  // memcpy can be dropped), that it is not read or written between the call and
899  // the memcpy, and that writing beyond the end of it is undefined.
900  SmallVector<User*, 8> srcUseList(srcAlloca->user_begin(),
901  srcAlloca->user_end());
902  while (!srcUseList.empty()) {
903  User *U = srcUseList.pop_back_val();
904 
905  if (isa<BitCastInst>(U) || isa<AddrSpaceCastInst>(U)) {
906  for (User *UU : U->users())
907  srcUseList.push_back(UU);
908  continue;
909  }
910  if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(U)) {
911  if (!G->hasAllZeroIndices())
912  return false;
913 
914  for (User *UU : U->users())
915  srcUseList.push_back(UU);
916  continue;
917  }
918  if (const IntrinsicInst *IT = dyn_cast<IntrinsicInst>(U))
919  if (IT->getIntrinsicID() == Intrinsic::lifetime_start ||
920  IT->getIntrinsicID() == Intrinsic::lifetime_end)
921  continue;
922 
923  if (U != C && U != cpy)
924  return false;
925  }
926 
927  // Check that src isn't captured by the called function since the
928  // transformation can cause aliasing issues in that case.
929  for (unsigned i = 0, e = CS.arg_size(); i != e; ++i)
930  if (CS.getArgument(i) == cpySrc && !CS.doesNotCapture(i))
931  return false;
932 
933  // Since we're changing the parameter to the callsite, we need to make sure
934  // that what would be the new parameter dominates the callsite.
935  DominatorTree &DT = LookupDomTree();
936  if (Instruction *cpyDestInst = dyn_cast<Instruction>(cpyDest))
937  if (!DT.dominates(cpyDestInst, C))
938  return false;
939 
940  // In addition to knowing that the call does not access src in some
941  // unexpected manner, for example via a global, which we deduce from
942  // the use analysis, we also need to know that it does not sneakily
943  // access dest. We rely on AA to figure this out for us.
944  AliasAnalysis &AA = LookupAliasAnalysis();
945  ModRefInfo MR = AA.getModRefInfo(C, cpyDest, srcSize);
946  // If necessary, perform additional analysis.
947  if (isModOrRefSet(MR))
948  MR = AA.callCapturesBefore(C, cpyDest, srcSize, &DT);
949  if (isModOrRefSet(MR))
950  return false;
951 
952  // We can't create address space casts here because we don't know if they're
953  // safe for the target.
954  if (cpySrc->getType()->getPointerAddressSpace() !=
955  cpyDest->getType()->getPointerAddressSpace())
956  return false;
957  for (unsigned i = 0; i < CS.arg_size(); ++i)
958  if (CS.getArgument(i)->stripPointerCasts() == cpySrc &&
959  cpySrc->getType()->getPointerAddressSpace() !=
961  return false;
962 
963  // All the checks have passed, so do the transformation.
964  bool changedArgument = false;
965  for (unsigned i = 0; i < CS.arg_size(); ++i)
966  if (CS.getArgument(i)->stripPointerCasts() == cpySrc) {
967  Value *Dest = cpySrc->getType() == cpyDest->getType() ? cpyDest
968  : CastInst::CreatePointerCast(cpyDest, cpySrc->getType(),
969  cpyDest->getName(), C);
970  changedArgument = true;
971  if (CS.getArgument(i)->getType() == Dest->getType())
972  CS.setArgument(i, Dest);
973  else
975  CS.getArgument(i)->getType(), Dest->getName(), C));
976  }
977 
978  if (!changedArgument)
979  return false;
980 
981  // If the destination wasn't sufficiently aligned then increase its alignment.
982  if (!isDestSufficientlyAligned) {
983  assert(isa<AllocaInst>(cpyDest) && "Can only increase alloca alignment!");
984  cast<AllocaInst>(cpyDest)->setAlignment(srcAlign);
985  }
986 
987  // Drop any cached information about the call, because we may have changed
988  // its dependence information by changing its parameter.
989  MD->removeInstruction(C);
990 
991  // Update AA metadata
992  // FIXME: MD_tbaa_struct and MD_mem_parallel_loop_access should also be
993  // handled here, but combineMetadata doesn't support them yet
994  unsigned KnownIDs[] = {LLVMContext::MD_tbaa, LLVMContext::MD_alias_scope,
997  combineMetadata(C, cpy, KnownIDs);
998 
999  // Remove the memcpy.
1000  MD->removeInstruction(cpy);
1001  ++NumMemCpyInstr;
1002 
1003  return true;
1004 }
1005 
1006 /// We've found that the (upward scanning) memory dependence of memcpy 'M' is
1007 /// the memcpy 'MDep'. Try to simplify M to copy from MDep's input if we can.
1008 bool MemCpyOptPass::processMemCpyMemCpyDependence(MemCpyInst *M,
1009  MemCpyInst *MDep) {
1010  // We can only transforms memcpy's where the dest of one is the source of the
1011  // other.
1012  if (M->getSource() != MDep->getDest() || MDep->isVolatile())
1013  return false;
1014 
1015  // If dep instruction is reading from our current input, then it is a noop
1016  // transfer and substituting the input won't change this instruction. Just
1017  // ignore the input and let someone else zap MDep. This handles cases like:
1018  // memcpy(a <- a)
1019  // memcpy(b <- a)
1020  if (M->getSource() == MDep->getSource())
1021  return false;
1022 
1023  // Second, the length of the memcpy's must be the same, or the preceding one
1024  // must be larger than the following one.
1025  ConstantInt *MDepLen = dyn_cast<ConstantInt>(MDep->getLength());
1026  ConstantInt *MLen = dyn_cast<ConstantInt>(M->getLength());
1027  if (!MDepLen || !MLen || MDepLen->getZExtValue() < MLen->getZExtValue())
1028  return false;
1029 
1030  AliasAnalysis &AA = LookupAliasAnalysis();
1031 
1032  // Verify that the copied-from memory doesn't change in between the two
1033  // transfers. For example, in:
1034  // memcpy(a <- b)
1035  // *b = 42;
1036  // memcpy(c <- a)
1037  // It would be invalid to transform the second memcpy into memcpy(c <- b).
1038  //
1039  // TODO: If the code between M and MDep is transparent to the destination "c",
1040  // then we could still perform the xform by moving M up to the first memcpy.
1041  //
1042  // NOTE: This is conservative, it will stop on any read from the source loc,
1043  // not just the defining memcpy.
1044  MemDepResult SourceDep =
1045  MD->getPointerDependencyFrom(MemoryLocation::getForSource(MDep), false,
1046  M->getIterator(), M->getParent());
1047  if (!SourceDep.isClobber() || SourceDep.getInst() != MDep)
1048  return false;
1049 
1050  // If the dest of the second might alias the source of the first, then the
1051  // source and dest might overlap. We still want to eliminate the intermediate
1052  // value, but we have to generate a memmove instead of memcpy.
1053  bool UseMemMove = false;
1056  UseMemMove = true;
1057 
1058  // If all checks passed, then we can transform M.
1059 
1060  // TODO: Is this worth it if we're creating a less aligned memcpy? For
1061  // example we could be moving from movaps -> movq on x86.
1062  IRBuilder<> Builder(M);
1063  if (UseMemMove)
1064  Builder.CreateMemMove(M->getRawDest(), M->getDestAlignment(),
1065  MDep->getRawSource(), MDep->getSourceAlignment(),
1066  M->getLength(), M->isVolatile());
1067  else
1068  Builder.CreateMemCpy(M->getRawDest(), M->getDestAlignment(),
1069  MDep->getRawSource(), MDep->getSourceAlignment(),
1070  M->getLength(), M->isVolatile());
1071 
1072  // Remove the instruction we're replacing.
1073  MD->removeInstruction(M);
1074  M->eraseFromParent();
1075  ++NumMemCpyInstr;
1076  return true;
1077 }
1078 
1079 /// We've found that the (upward scanning) memory dependence of \p MemCpy is
1080 /// \p MemSet. Try to simplify \p MemSet to only set the trailing bytes that
1081 /// weren't copied over by \p MemCpy.
1082 ///
1083 /// In other words, transform:
1084 /// \code
1085 /// memset(dst, c, dst_size);
1086 /// memcpy(dst, src, src_size);
1087 /// \endcode
1088 /// into:
1089 /// \code
1090 /// memcpy(dst, src, src_size);
1091 /// memset(dst + src_size, c, dst_size <= src_size ? 0 : dst_size - src_size);
1092 /// \endcode
1093 bool MemCpyOptPass::processMemSetMemCpyDependence(MemCpyInst *MemCpy,
1094  MemSetInst *MemSet) {
1095  // We can only transform memset/memcpy with the same destination.
1096  if (MemSet->getDest() != MemCpy->getDest())
1097  return false;
1098 
1099  // Check that there are no other dependencies on the memset destination.
1100  MemDepResult DstDepInfo =
1101  MD->getPointerDependencyFrom(MemoryLocation::getForDest(MemSet), false,
1102  MemCpy->getIterator(), MemCpy->getParent());
1103  if (DstDepInfo.getInst() != MemSet)
1104  return false;
1105 
1106  // Use the same i8* dest as the memcpy, killing the memset dest if different.
1107  Value *Dest = MemCpy->getRawDest();
1108  Value *DestSize = MemSet->getLength();
1109  Value *SrcSize = MemCpy->getLength();
1110 
1111  // By default, create an unaligned memset.
1112  unsigned Align = 1;
1113  // If Dest is aligned, and SrcSize is constant, use the minimum alignment
1114  // of the sum.
1115  const unsigned DestAlign =
1116  std::max(MemSet->getDestAlignment(), MemCpy->getDestAlignment());
1117  if (DestAlign > 1)
1118  if (ConstantInt *SrcSizeC = dyn_cast<ConstantInt>(SrcSize))
1119  Align = MinAlign(SrcSizeC->getZExtValue(), DestAlign);
1120 
1121  IRBuilder<> Builder(MemCpy);
1122 
1123  // If the sizes have different types, zext the smaller one.
1124  if (DestSize->getType() != SrcSize->getType()) {
1125  if (DestSize->getType()->getIntegerBitWidth() >
1126  SrcSize->getType()->getIntegerBitWidth())
1127  SrcSize = Builder.CreateZExt(SrcSize, DestSize->getType());
1128  else
1129  DestSize = Builder.CreateZExt(DestSize, SrcSize->getType());
1130  }
1131 
1132  Value *Ule = Builder.CreateICmpULE(DestSize, SrcSize);
1133  Value *SizeDiff = Builder.CreateSub(DestSize, SrcSize);
1134  Value *MemsetLen = Builder.CreateSelect(
1135  Ule, ConstantInt::getNullValue(DestSize->getType()), SizeDiff);
1136  Builder.CreateMemSet(Builder.CreateGEP(Dest, SrcSize), MemSet->getOperand(1),
1137  MemsetLen, Align);
1138 
1139  MD->removeInstruction(MemSet);
1140  MemSet->eraseFromParent();
1141  return true;
1142 }
1143 
1144 /// Transform memcpy to memset when its source was just memset.
1145 /// In other words, turn:
1146 /// \code
1147 /// memset(dst1, c, dst1_size);
1148 /// memcpy(dst2, dst1, dst2_size);
1149 /// \endcode
1150 /// into:
1151 /// \code
1152 /// memset(dst1, c, dst1_size);
1153 /// memset(dst2, c, dst2_size);
1154 /// \endcode
1155 /// When dst2_size <= dst1_size.
1156 ///
1157 /// The \p MemCpy must have a Constant length.
1158 bool MemCpyOptPass::performMemCpyToMemSetOptzn(MemCpyInst *MemCpy,
1159  MemSetInst *MemSet) {
1160  AliasAnalysis &AA = LookupAliasAnalysis();
1161 
1162  // Make sure that memcpy(..., memset(...), ...), that is we are memsetting and
1163  // memcpying from the same address. Otherwise it is hard to reason about.
1164  if (!AA.isMustAlias(MemSet->getRawDest(), MemCpy->getRawSource()))
1165  return false;
1166 
1167  ConstantInt *CopySize = cast<ConstantInt>(MemCpy->getLength());
1168  ConstantInt *MemSetSize = dyn_cast<ConstantInt>(MemSet->getLength());
1169  // Make sure the memcpy doesn't read any more than what the memset wrote.
1170  // Don't worry about sizes larger than i64.
1171  if (!MemSetSize || CopySize->getZExtValue() > MemSetSize->getZExtValue())
1172  return false;
1173 
1174  IRBuilder<> Builder(MemCpy);
1175  Builder.CreateMemSet(MemCpy->getRawDest(), MemSet->getOperand(1),
1176  CopySize, MemCpy->getDestAlignment());
1177  return true;
1178 }
1179 
1180 /// Perform simplification of memcpy's. If we have memcpy A
1181 /// which copies X to Y, and memcpy B which copies Y to Z, then we can rewrite
1182 /// B to be a memcpy from X to Z (or potentially a memmove, depending on
1183 /// circumstances). This allows later passes to remove the first memcpy
1184 /// altogether.
1185 bool MemCpyOptPass::processMemCpy(MemCpyInst *M) {
1186  // We can only optimize non-volatile memcpy's.
1187  if (M->isVolatile()) return false;
1188 
1189  // If the source and destination of the memcpy are the same, then zap it.
1190  if (M->getSource() == M->getDest()) {
1191  MD->removeInstruction(M);
1192  M->eraseFromParent();
1193  return false;
1194  }
1195 
1196  // If copying from a constant, try to turn the memcpy into a memset.
1197  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(M->getSource()))
1198  if (GV->isConstant() && GV->hasDefinitiveInitializer())
1199  if (Value *ByteVal = isBytewiseValue(GV->getInitializer())) {
1200  IRBuilder<> Builder(M);
1201  Builder.CreateMemSet(M->getRawDest(), ByteVal, M->getLength(),
1202  M->getDestAlignment(), false);
1203  MD->removeInstruction(M);
1204  M->eraseFromParent();
1205  ++NumCpyToSet;
1206  return true;
1207  }
1208 
1209  MemDepResult DepInfo = MD->getDependency(M);
1210 
1211  // Try to turn a partially redundant memset + memcpy into
1212  // memcpy + smaller memset. We don't need the memcpy size for this.
1213  if (DepInfo.isClobber())
1214  if (MemSetInst *MDep = dyn_cast<MemSetInst>(DepInfo.getInst()))
1215  if (processMemSetMemCpyDependence(M, MDep))
1216  return true;
1217 
1218  // The optimizations after this point require the memcpy size.
1219  ConstantInt *CopySize = dyn_cast<ConstantInt>(M->getLength());
1220  if (!CopySize) return false;
1221 
1222  // There are four possible optimizations we can do for memcpy:
1223  // a) memcpy-memcpy xform which exposes redundance for DSE.
1224  // b) call-memcpy xform for return slot optimization.
1225  // c) memcpy from freshly alloca'd space or space that has just started its
1226  // lifetime copies undefined data, and we can therefore eliminate the
1227  // memcpy in favor of the data that was already at the destination.
1228  // d) memcpy from a just-memset'd source can be turned into memset.
1229  if (DepInfo.isClobber()) {
1230  if (CallInst *C = dyn_cast<CallInst>(DepInfo.getInst())) {
1231  // FIXME: Can we pass in either of dest/src alignment here instead
1232  // of conservatively taking the minimum?
1233  unsigned Align = MinAlign(M->getDestAlignment(), M->getSourceAlignment());
1234  if (performCallSlotOptzn(M, M->getDest(), M->getSource(),
1235  CopySize->getZExtValue(), Align,
1236  C)) {
1237  MD->removeInstruction(M);
1238  M->eraseFromParent();
1239  return true;
1240  }
1241  }
1242  }
1243 
1245  MemDepResult SrcDepInfo = MD->getPointerDependencyFrom(
1246  SrcLoc, true, M->getIterator(), M->getParent());
1247 
1248  if (SrcDepInfo.isClobber()) {
1249  if (MemCpyInst *MDep = dyn_cast<MemCpyInst>(SrcDepInfo.getInst()))
1250  return processMemCpyMemCpyDependence(M, MDep);
1251  } else if (SrcDepInfo.isDef()) {
1252  Instruction *I = SrcDepInfo.getInst();
1253  bool hasUndefContents = false;
1254 
1255  if (isa<AllocaInst>(I)) {
1256  hasUndefContents = true;
1257  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
1258  if (II->getIntrinsicID() == Intrinsic::lifetime_start)
1259  if (ConstantInt *LTSize = dyn_cast<ConstantInt>(II->getArgOperand(0)))
1260  if (LTSize->getZExtValue() >= CopySize->getZExtValue())
1261  hasUndefContents = true;
1262  }
1263 
1264  if (hasUndefContents) {
1265  MD->removeInstruction(M);
1266  M->eraseFromParent();
1267  ++NumMemCpyInstr;
1268  return true;
1269  }
1270  }
1271 
1272  if (SrcDepInfo.isClobber())
1273  if (MemSetInst *MDep = dyn_cast<MemSetInst>(SrcDepInfo.getInst()))
1274  if (performMemCpyToMemSetOptzn(M, MDep)) {
1275  MD->removeInstruction(M);
1276  M->eraseFromParent();
1277  ++NumCpyToSet;
1278  return true;
1279  }
1280 
1281  return false;
1282 }
1283 
1284 /// Transforms memmove calls to memcpy calls when the src/dst are guaranteed
1285 /// not to alias.
1286 bool MemCpyOptPass::processMemMove(MemMoveInst *M) {
1287  AliasAnalysis &AA = LookupAliasAnalysis();
1288 
1289  if (!TLI->has(LibFunc_memmove))
1290  return false;
1291 
1292  // See if the pointers alias.
1295  return false;
1296 
1297  LLVM_DEBUG(dbgs() << "MemCpyOptPass: Optimizing memmove -> memcpy: " << *M
1298  << "\n");
1299 
1300  // If not, then we know we can transform this.
1301  Type *ArgTys[3] = { M->getRawDest()->getType(),
1302  M->getRawSource()->getType(),
1303  M->getLength()->getType() };
1305  Intrinsic::memcpy, ArgTys));
1306 
1307  // MemDep may have over conservative information about this instruction, just
1308  // conservatively flush it from the cache.
1309  MD->removeInstruction(M);
1310 
1311  ++NumMoveToCpy;
1312  return true;
1313 }
1314 
1315 /// This is called on every byval argument in call sites.
1316 bool MemCpyOptPass::processByValArgument(CallSite CS, unsigned ArgNo) {
1317  const DataLayout &DL = CS.getCaller()->getParent()->getDataLayout();
1318  // Find out what feeds this byval argument.
1319  Value *ByValArg = CS.getArgument(ArgNo);
1320  Type *ByValTy = cast<PointerType>(ByValArg->getType())->getElementType();
1321  uint64_t ByValSize = DL.getTypeAllocSize(ByValTy);
1322  MemDepResult DepInfo = MD->getPointerDependencyFrom(
1323  MemoryLocation(ByValArg, ByValSize), true,
1325  if (!DepInfo.isClobber())
1326  return false;
1327 
1328  // If the byval argument isn't fed by a memcpy, ignore it. If it is fed by
1329  // a memcpy, see if we can byval from the source of the memcpy instead of the
1330  // result.
1331  MemCpyInst *MDep = dyn_cast<MemCpyInst>(DepInfo.getInst());
1332  if (!MDep || MDep->isVolatile() ||
1333  ByValArg->stripPointerCasts() != MDep->getDest())
1334  return false;
1335 
1336  // The length of the memcpy must be larger or equal to the size of the byval.
1337  ConstantInt *C1 = dyn_cast<ConstantInt>(MDep->getLength());
1338  if (!C1 || C1->getValue().getZExtValue() < ByValSize)
1339  return false;
1340 
1341  // Get the alignment of the byval. If the call doesn't specify the alignment,
1342  // then it is some target specific value that we can't know.
1343  unsigned ByValAlign = CS.getParamAlignment(ArgNo);
1344  if (ByValAlign == 0) return false;
1345 
1346  // If it is greater than the memcpy, then we check to see if we can force the
1347  // source of the memcpy to the alignment we need. If we fail, we bail out.
1348  AssumptionCache &AC = LookupAssumptionCache();
1349  DominatorTree &DT = LookupDomTree();
1350  if (MDep->getSourceAlignment() < ByValAlign &&
1351  getOrEnforceKnownAlignment(MDep->getSource(), ByValAlign, DL,
1352  CS.getInstruction(), &AC, &DT) < ByValAlign)
1353  return false;
1354 
1355  // The address space of the memcpy source must match the byval argument
1356  if (MDep->getSource()->getType()->getPointerAddressSpace() !=
1357  ByValArg->getType()->getPointerAddressSpace())
1358  return false;
1359 
1360  // Verify that the copied-from memory doesn't change in between the memcpy and
1361  // the byval call.
1362  // memcpy(a <- b)
1363  // *b = 42;
1364  // foo(*a)
1365  // It would be invalid to transform the second memcpy into foo(*b).
1366  //
1367  // NOTE: This is conservative, it will stop on any read from the source loc,
1368  // not just the defining memcpy.
1369  MemDepResult SourceDep = MD->getPointerDependencyFrom(
1370  MemoryLocation::getForSource(MDep), false,
1371  CS.getInstruction()->getIterator(), MDep->getParent());
1372  if (!SourceDep.isClobber() || SourceDep.getInst() != MDep)
1373  return false;
1374 
1375  Value *TmpCast = MDep->getSource();
1376  if (MDep->getSource()->getType() != ByValArg->getType())
1377  TmpCast = new BitCastInst(MDep->getSource(), ByValArg->getType(),
1378  "tmpcast", CS.getInstruction());
1379 
1380  LLVM_DEBUG(dbgs() << "MemCpyOptPass: Forwarding memcpy to byval:\n"
1381  << " " << *MDep << "\n"
1382  << " " << *CS.getInstruction() << "\n");
1383 
1384  // Otherwise we're good! Update the byval argument.
1385  CS.setArgument(ArgNo, TmpCast);
1386  ++NumMemCpyInstr;
1387  return true;
1388 }
1389 
1390 /// Executes one iteration of MemCpyOptPass.
1391 bool MemCpyOptPass::iterateOnFunction(Function &F) {
1392  bool MadeChange = false;
1393 
1394  DominatorTree &DT = LookupDomTree();
1395 
1396  // Walk all instruction in the function.
1397  for (BasicBlock &BB : F) {
1398  // Skip unreachable blocks. For example processStore assumes that an
1399  // instruction in a BB can't be dominated by a later instruction in the
1400  // same BB (which is a scenario that can happen for an unreachable BB that
1401  // has itself as a predecessor).
1402  if (!DT.isReachableFromEntry(&BB))
1403  continue;
1404 
1405  for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); BI != BE;) {
1406  // Avoid invalidating the iterator.
1407  Instruction *I = &*BI++;
1408 
1409  bool RepeatInstruction = false;
1410 
1411  if (StoreInst *SI = dyn_cast<StoreInst>(I))
1412  MadeChange |= processStore(SI, BI);
1413  else if (MemSetInst *M = dyn_cast<MemSetInst>(I))
1414  RepeatInstruction = processMemSet(M, BI);
1415  else if (MemCpyInst *M = dyn_cast<MemCpyInst>(I))
1416  RepeatInstruction = processMemCpy(M);
1417  else if (MemMoveInst *M = dyn_cast<MemMoveInst>(I))
1418  RepeatInstruction = processMemMove(M);
1419  else if (auto CS = CallSite(I)) {
1420  for (unsigned i = 0, e = CS.arg_size(); i != e; ++i)
1421  if (CS.isByValArgument(i))
1422  MadeChange |= processByValArgument(CS, i);
1423  }
1424 
1425  // Reprocess the instruction if desired.
1426  if (RepeatInstruction) {
1427  if (BI != BB.begin())
1428  --BI;
1429  MadeChange = true;
1430  }
1431  }
1432  }
1433 
1434  return MadeChange;
1435 }
1436 
1438  auto &MD = AM.getResult<MemoryDependenceAnalysis>(F);
1439  auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
1440 
1441  auto LookupAliasAnalysis = [&]() -> AliasAnalysis & {
1442  return AM.getResult<AAManager>(F);
1443  };
1444  auto LookupAssumptionCache = [&]() -> AssumptionCache & {
1445  return AM.getResult<AssumptionAnalysis>(F);
1446  };
1447  auto LookupDomTree = [&]() -> DominatorTree & {
1448  return AM.getResult<DominatorTreeAnalysis>(F);
1449  };
1450 
1451  bool MadeChange = runImpl(F, &MD, &TLI, LookupAliasAnalysis,
1452  LookupAssumptionCache, LookupDomTree);
1453  if (!MadeChange)
1454  return PreservedAnalyses::all();
1455 
1456  PreservedAnalyses PA;
1457  PA.preserveSet<CFGAnalyses>();
1458  PA.preserve<GlobalsAA>();
1460  return PA;
1461 }
1462 
1465  std::function<AliasAnalysis &()> LookupAliasAnalysis_,
1466  std::function<AssumptionCache &()> LookupAssumptionCache_,
1467  std::function<DominatorTree &()> LookupDomTree_) {
1468  bool MadeChange = false;
1469  MD = MD_;
1470  TLI = TLI_;
1471  LookupAliasAnalysis = std::move(LookupAliasAnalysis_);
1472  LookupAssumptionCache = std::move(LookupAssumptionCache_);
1473  LookupDomTree = std::move(LookupDomTree_);
1474 
1475  // If we don't have at least memset and memcpy, there is little point of doing
1476  // anything here. These are required by a freestanding implementation, so if
1477  // even they are disabled, there is no point in trying hard.
1478  if (!TLI->has(LibFunc_memset) || !TLI->has(LibFunc_memcpy))
1479  return false;
1480 
1481  while (true) {
1482  if (!iterateOnFunction(F))
1483  break;
1484  MadeChange = true;
1485  }
1486 
1487  MD = nullptr;
1488  return MadeChange;
1489 }
1490 
1491 /// This is the main transformation entry point for a function.
1493  if (skipFunction(F))
1494  return false;
1495 
1496  auto *MD = &getAnalysis<MemoryDependenceWrapperPass>().getMemDep();
1497  auto *TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1498 
1499  auto LookupAliasAnalysis = [this]() -> AliasAnalysis & {
1500  return getAnalysis<AAResultsWrapperPass>().getAAResults();
1501  };
1502  auto LookupAssumptionCache = [this, &F]() -> AssumptionCache & {
1503  return getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
1504  };
1505  auto LookupDomTree = [this]() -> DominatorTree & {
1506  return getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1507  };
1508 
1509  return Impl.runImpl(F, MD, TLI, LookupAliasAnalysis, LookupAssumptionCache,
1510  LookupDomTree);
1511 }
Legacy wrapper pass to provide the GlobalsAAResult object.
uint64_t CallInst * C
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:68
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
const_iterator end(StringRef path)
Get end iterator over path.
Definition: Path.cpp:250
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
Function * getCalledFunction() const
Return the function called, or null if this is an indirect function invocation.
static bool runImpl(Function &F, TargetLibraryInfo &TLI, DominatorTree &DT)
This is the entry point for all transforms.
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
Provides a lazy, caching interface for making common memory aliasing information queries, backed by LLVM&#39;s alias analysis passes.
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1547
unsigned getOrEnforceKnownAlignment(Value *V, unsigned PrefAlign, const DataLayout &DL, const Instruction *CxtI=nullptr, AssumptionCache *AC=nullptr, const DominatorTree *DT=nullptr)
Try to ensure that the alignment of V is at least PrefAlign bytes.
Definition: Local.cpp:1165
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
This class represents an incoming formal argument to a Function.
Definition: Argument.h:30
const_iterator begin(StringRef path, Style style=Style::native)
Get begin iterator over path.
Definition: Path.cpp:241
unsigned arg_size() const
Definition: CallSite.h:219
typename SuperClass::const_iterator const_iterator
Definition: SmallVector.h:328
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:687
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
unsigned getParamAlignment(unsigned ArgNo) const
Extract the alignment for a call or parameter (0=unknown).
Definition: CallSite.h:406
Value * isBytewiseValue(Value *V)
If the specified value can be set by repeating the same byte in memory, return the i8 value that it i...
INITIALIZE_PASS_BEGIN(MemCpyOptLegacyPass, "memcpyopt", "MemCpy Optimization", false, false) INITIALIZE_PASS_END(MemCpyOptLegacyPass
This is the interface for a simple mod/ref and alias analysis over globals.
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:262
Implements a dense probed hash-table based set.
Definition: DenseSet.h:221
const StructLayout * getStructLayout(StructType *Ty) const
Returns a StructLayout object, indicating the alignment of the struct, its size, and the offsets of i...
Definition: DataLayout.cpp:588
bool isNoAlias(const MemoryLocation &LocA, const MemoryLocation &LocB)
A trivial helper function to check to see if the specified pointers are no-alias. ...
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
This class represents a function call, abstracting a target machine&#39;s calling convention.
An immutable pass that tracks lazily created AssumptionCache objects.
unsigned getSourceAlignment() const
Value * getValue() const
A cache of @llvm.assume calls within a function.
static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset, const DataLayout &DL)
Return true if Ptr1 is provably equal to Ptr2 plus a constant offset, and return that constant offset...
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
This class wraps the llvm.memset intrinsic.
STATISTIC(NumFunctions, "Total number of functions")
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:225
F(f)
unsigned getPointerAddressSpace() const
Get the address space of this pointer or pointer vector type.
Definition: DerivedTypes.h:503
CallInst * CreateMemSet(Value *Ptr, Value *Val, uint64_t Size, unsigned Align, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memset to the specified pointer and the specified value.
Definition: IRBuilder.h:404
An instruction for reading from memory.
Definition: Instructions.h:164
Hexagon Common GEP
Value * CreateICmpULE(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1756
Value * getLength() const
bool isReachableFromEntry(const Use &U) const
Provide an overload for a Use.
Definition: Dominators.cpp:295
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:258
Value * getDest() const
This is just like getRawDest, but it strips off any cast instructions (including addrspacecast) that ...
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:51
bool isDef() const
Tests if this MemDepResult represents a query that is an instruction definition dependency.
static int64_t GetOffsetFromIndex(const GEPOperator *GEP, unsigned Idx, bool &VariableIdxFound, const DataLayout &DL)
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:361
unsigned getAlignment() const
Return the alignment of the memory that is being allocated by the instruction.
Definition: Instructions.h:109
static unsigned findStoreAlignment(const DataLayout &DL, const StoreInst *SI)
bool isClobber() const
Tests if this MemDepResult represents a query that is an instruction clobber dependency.
This class wraps the llvm.memmove intrinsic.
Class to represent struct types.
Definition: DerivedTypes.h:201
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:731
InstrTy * getInstruction() const
Definition: CallSite.h:92
An analysis that produces MemoryDependenceResults for a function.
CallInst * CreateMemMove(Value *Dst, unsigned DstAlign, Value *Src, unsigned SrcAlign, uint64_t Size, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memmove between the specified pointers.
Definition: IRBuilder.h:494
unsigned getDestAlignment() const
void setArgument(unsigned ArgNo, Value *newVal)
Definition: CallSite.h:191
auto reverse(ContainerTy &&C, typename std::enable_if< has_rbegin< ContainerTy >::value >::type *=nullptr) -> decltype(make_range(C.rbegin(), C.rend()))
Definition: STLExtras.h:237
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
static MemoryLocation getForDest(const MemIntrinsic *MI)
Return a location representing the destination of a memory set or transfer.
This class represents a no-op cast from one type to another.
MDNode * getMetadata(unsigned KindID) const
Get the metadata of given kind attached to this Instruction.
Definition: Instruction.h:200
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:138
auto lower_bound(R &&Range, ForwardIt I) -> decltype(adl_begin(Range))
Provide wrappers to std::lower_bound which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1004
Value * CreateSub(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:979
An instruction for storing to memory.
Definition: Instructions.h:306
Value * CreateZExt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1556
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:142
Function * getDeclaration(Module *M, ID id, ArrayRef< Type *> Tys=None)
Create or insert an LLVM Function declaration for an intrinsic, and return it.
Definition: Function.cpp:1001
Value * getOperand(unsigned i) const
Definition: User.h:170
Value * getOperand(unsigned i_nocapture) const
constexpr uint64_t MinAlign(uint64_t A, uint64_t B)
A and B are either alignments or offsets.
Definition: MathExtras.h:608
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:837
static bool runOnFunction(Function &F, bool PostInlining)
#define P(N)
static MemoryLocation get(const LoadInst *LI)
Return a location with information about the memory reference by the given instruction.
unsigned getNumOperands() const
uint64_t getZExtValue() const
Return the constant as a 64-bit unsigned integer value after it has been zero extended as appropriate...
Definition: Constants.h:149
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:287
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:117
This file contains the declarations for the subclasses of Constant, which represent the different fla...
Value * CreateSelect(Value *C, Value *True, Value *False, const Twine &Name="", Instruction *MDFrom=nullptr)
Definition: IRBuilder.h:1901
A manager for alias analyses.
bool mayThrow() const
Return true if this instruction may throw an exception.
Represent the analysis usage information of a pass.
bool any_of(R &&Range, UnaryPredicate P)
Provide wrappers to std::any_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:915
void setCalledFunction(Value *Fn)
Set the function called.
Analysis pass providing a never-invalidated alias analysis result.
static const unsigned End
unsigned getLargestLegalIntTypeSizeInBits() const
Returns the size of largest legal integer type size, or 0 if none are set.
Definition: DataLayout.cpp:764
FunctionPass * createMemCpyOptPass()
The public interface to this file...
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
self_iterator getIterator()
Definition: ilist_node.h:82
static CastInst * CreatePointerCast(Value *S, Type *Ty, const Twine &Name, BasicBlock *InsertAtEnd)
Create a BitCast AddrSpaceCast, or a PtrToInt cast instruction.
bool doesNotCapture(unsigned OpNo) const
Determine whether this data operand is not captured.
Definition: CallSite.h:593
const Value * stripPointerCasts() const
Strip off pointer casts, all-zero GEPs, and aliases.
Definition: Value.cpp:538
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
void initializeMemCpyOptLegacyPassPass(PassRegistry &)
const Value * getArraySize() const
Get the number of elements allocated.
Definition: Instructions.h:93
A wrapper analysis pass for the legacy pass manager that exposes a MemoryDepnedenceResults instance...
bool isVolatile() const
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
Type * getAllocatedType() const
Return the type that is being allocated by the instruction.
Definition: Instructions.h:102
A memory dependence query can return one of three different answers.
bool runImpl(Function &F, MemoryDependenceResults *MD_, TargetLibraryInfo *TLI_, std::function< AliasAnalysis &()> LookupAliasAnalysis_, std::function< AssumptionCache &()> LookupAssumptionCache_, std::function< DominatorTree &()> LookupDomTree_)
The two locations may or may not alias. This is the least precise result.
Definition: AliasAnalysis.h:87
Value * CreateGEP(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &Name="")
Definition: IRBuilder.h:1374
Representation for a specific memory location.
A function analysis which provides an AssumptionCache.
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
Iterator for intrusive lists based on ilist_node.
unsigned getNumOperands() const
Definition: User.h:192
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
ValTy * getArgument(unsigned ArgNo) const
Definition: CallSite.h:186
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:244
Module.h This file contains the declarations for the Module class.
Provides information about what library functions are available for the current target.
unsigned getABITypeAlignment(Type *Ty) const
Returns the minimum ABI-required alignment for the specified type.
Definition: DataLayout.cpp:722
const DataFlowGraph & G
Definition: RDFGraph.cpp:211
static unsigned findLoadAlignment(const DataLayout &DL, const LoadInst *LI)
CallInst * CreateMemCpy(Value *Dst, unsigned DstAlign, Value *Src, unsigned SrcAlign, uint64_t Size, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *TBAAStructTag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memcpy between the specified pointers.
Definition: IRBuilder.h:446
This class wraps the llvm.memcpy intrinsic.
void setPreservesCFG()
This function should be called by the pass, iff they do not:
Definition: Pass.cpp:286
Value * getRawSource() const
Return the arguments to the instruction.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:56
ModRefInfo callCapturesBefore(const Instruction *I, const MemoryLocation &MemLoc, DominatorTree *DT, OrderedBasicBlock *OBB=nullptr)
Return information about whether a particular call site modifies or reads the specified memory locati...
ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc)
getModRefInfo (for call sites) - Return information about whether a particular call site modifies or ...
typename SuperClass::iterator iterator
Definition: SmallVector.h:327
iterator_range< user_iterator > users()
Definition: Value.h:399
bool isMustAlias(const MemoryLocation &LocA, const MemoryLocation &LocB)
A trivial helper function to check to see if the specified pointers are must-alias.
MemCpy Optimization
Represents analyses that only rely on functions&#39; control flow.
Definition: PassManager.h:114
static cl::opt< ITMode > IT(cl::desc("IT block support"), cl::Hidden, cl::init(DefaultIT), cl::ZeroOrMore, cl::values(clEnumValN(DefaultIT, "arm-default-it", "Generate IT block based on arch"), clEnumValN(RestrictedIT, "arm-restrict-it", "Disallow deprecated IT based on ARMv8"), clEnumValN(NoRestrictedIT, "arm-no-restrict-it", "Allow IT blocks based on ARMv7")))
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:428
LLVM_NODISCARD bool isModSet(const ModRefInfo MRI)
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:121
FunTy * getCaller() const
Return the caller function for this call site.
Definition: CallSite.h:267
bool isVolatile() const
Return true if this is a store to a volatile memory location.
Definition: Instructions.h:339
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:543
unsigned getAlignment() const
Return the alignment of the access that is being performed.
Definition: Instructions.h:226
Instruction * getInst() const
If this is a normal dependency, returns the instruction that is depended on.
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:97
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:62
This file provides utility analysis objects describing memory locations.
void preserveSet()
Mark an analysis set as preserved.
Definition: PassManager.h:189
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:224
Establish a view to a call site for examination.
Definition: CallSite.h:713
#define I(x, y, z)
Definition: MD5.cpp:58
bool isZero() const
This is just a convenience method to make client code smaller for a common code.
Definition: Constants.h:193
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:174
unsigned getAlignment() const
Return the alignment of the access that is being performed.
Definition: Instructions.h:351
static void addRange(SmallVectorImpl< ConstantInt *> &EndPoints, ConstantInt *Low, ConstantInt *High)
Definition: Metadata.cpp:968
bool isByValArgument(unsigned ArgNo) const
Determine whether this argument is passed by value.
Definition: CallSite.h:598
Analysis pass providing the TargetLibraryInfo.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
user_iterator user_begin()
Definition: Value.h:375
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:565
LLVM Value Representation.
Definition: Value.h:73
uint64_t getTypeStoreSize(Type *Ty) const
Returns the maximum number of bytes that may be overwritten by storing the specified type...
Definition: DataLayout.h:411
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
ModRefInfo
Flags indicating whether a memory access modifies or references memory.
Value * getSource() const
This is just like getRawSource, but it strips off any cast instructions that feed it...
print Print MemDeps of function
A container for analyses that lazily runs them and caches their results.
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:254
LLVM_NODISCARD bool isModOrRefSet(const ModRefInfo MRI)
static bool moveUp(AliasAnalysis &AA, StoreInst *SI, Instruction *P, const LoadInst *LI)
static unsigned findCommonAlignment(const DataLayout &DL, const StoreInst *SI, const LoadInst *LI)
A wrapper pass to provide the legacy pass manager access to a suitably prepared AAResults object...
bool isSimple() const
Definition: Instructions.h:387
int64_t getSExtValue() const
Return the constant as a 64-bit integer value after it has been sign extended as appropriate for the ...
Definition: Constants.h:157
This header defines various interfaces for pass management in LLVM.
#define LLVM_DEBUG(X)
Definition: Debug.h:119
Value * getPointerOperand()
Definition: Instructions.h:398
void combineMetadata(Instruction *K, const Instruction *J, ArrayRef< unsigned > KnownIDs)
Combine the metadata of two instructions so that K can replace J.
Definition: Local.cpp:2061
Value * getRawDest() const
constexpr char Args[]
Key for Kernel::Metadata::mArgs.
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:44
const BasicBlock * getParent() const
Definition: Instruction.h:67
an instruction to allocate memory on the stack
Definition: Instructions.h:60
gep_type_iterator gep_type_begin(const User *GEP)
static MemoryLocation getForSource(const MemTransferInst *MTI)
Return a location representing the source of a memory transfer.
user_iterator user_end()
Definition: Value.h:383