LLVM  10.0.0svn
ExpandMemCmp.cpp
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1 //===--- ExpandMemCmp.cpp - Expand memcmp() to load/stores ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This pass tries to expand memcmp() calls into optimally-sized loads and
10 // compares for the target.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/ADT/Statistic.h"
22 #include "llvm/IR/IRBuilder.h"
23 
24 using namespace llvm;
25 
26 #define DEBUG_TYPE "expandmemcmp"
27 
28 STATISTIC(NumMemCmpCalls, "Number of memcmp calls");
29 STATISTIC(NumMemCmpNotConstant, "Number of memcmp calls without constant size");
30 STATISTIC(NumMemCmpGreaterThanMax,
31  "Number of memcmp calls with size greater than max size");
32 STATISTIC(NumMemCmpInlined, "Number of inlined memcmp calls");
33 
35  "memcmp-num-loads-per-block", cl::Hidden, cl::init(1),
36  cl::desc("The number of loads per basic block for inline expansion of "
37  "memcmp that is only being compared against zero."));
38 
40  "max-loads-per-memcmp", cl::Hidden,
41  cl::desc("Set maximum number of loads used in expanded memcmp"));
42 
44  "max-loads-per-memcmp-opt-size", cl::Hidden,
45  cl::desc("Set maximum number of loads used in expanded memcmp for -Os/Oz"));
46 
47 namespace {
48 
49 
50 // This class provides helper functions to expand a memcmp library call into an
51 // inline expansion.
52 class MemCmpExpansion {
53  struct ResultBlock {
54  BasicBlock *BB = nullptr;
55  PHINode *PhiSrc1 = nullptr;
56  PHINode *PhiSrc2 = nullptr;
57 
58  ResultBlock() = default;
59  };
60 
61  CallInst *const CI;
62  ResultBlock ResBlock;
63  const uint64_t Size;
64  unsigned MaxLoadSize;
65  uint64_t NumLoadsNonOneByte;
66  const uint64_t NumLoadsPerBlockForZeroCmp;
67  std::vector<BasicBlock *> LoadCmpBlocks;
68  BasicBlock *EndBlock;
69  PHINode *PhiRes;
70  const bool IsUsedForZeroCmp;
71  const DataLayout &DL;
72  IRBuilder<> Builder;
73  // Represents the decomposition in blocks of the expansion. For example,
74  // comparing 33 bytes on X86+sse can be done with 2x16-byte loads and
75  // 1x1-byte load, which would be represented as [{16, 0}, {16, 16}, {32, 1}.
76  struct LoadEntry {
77  LoadEntry(unsigned LoadSize, uint64_t Offset)
78  : LoadSize(LoadSize), Offset(Offset) {
79  }
80 
81  // The size of the load for this block, in bytes.
82  unsigned LoadSize;
83  // The offset of this load from the base pointer, in bytes.
84  uint64_t Offset;
85  };
86  using LoadEntryVector = SmallVector<LoadEntry, 8>;
87  LoadEntryVector LoadSequence;
88 
89  void createLoadCmpBlocks();
90  void createResultBlock();
91  void setupResultBlockPHINodes();
92  void setupEndBlockPHINodes();
93  Value *getCompareLoadPairs(unsigned BlockIndex, unsigned &LoadIndex);
94  void emitLoadCompareBlock(unsigned BlockIndex);
95  void emitLoadCompareBlockMultipleLoads(unsigned BlockIndex,
96  unsigned &LoadIndex);
97  void emitLoadCompareByteBlock(unsigned BlockIndex, unsigned OffsetBytes);
98  void emitMemCmpResultBlock();
99  Value *getMemCmpExpansionZeroCase();
100  Value *getMemCmpEqZeroOneBlock();
101  Value *getMemCmpOneBlock();
102  Value *getPtrToElementAtOffset(Value *Source, Type *LoadSizeType,
103  uint64_t OffsetBytes);
104 
105  static LoadEntryVector
106  computeGreedyLoadSequence(uint64_t Size, llvm::ArrayRef<unsigned> LoadSizes,
107  unsigned MaxNumLoads, unsigned &NumLoadsNonOneByte);
108  static LoadEntryVector
109  computeOverlappingLoadSequence(uint64_t Size, unsigned MaxLoadSize,
110  unsigned MaxNumLoads,
111  unsigned &NumLoadsNonOneByte);
112 
113 public:
114  MemCmpExpansion(CallInst *CI, uint64_t Size,
116  const bool IsUsedForZeroCmp, const DataLayout &TheDataLayout);
117 
118  unsigned getNumBlocks();
119  uint64_t getNumLoads() const { return LoadSequence.size(); }
120 
121  Value *getMemCmpExpansion();
122 };
123 
124 MemCmpExpansion::LoadEntryVector MemCmpExpansion::computeGreedyLoadSequence(
125  uint64_t Size, llvm::ArrayRef<unsigned> LoadSizes,
126  const unsigned MaxNumLoads, unsigned &NumLoadsNonOneByte) {
127  NumLoadsNonOneByte = 0;
128  LoadEntryVector LoadSequence;
129  uint64_t Offset = 0;
130  while (Size && !LoadSizes.empty()) {
131  const unsigned LoadSize = LoadSizes.front();
132  const uint64_t NumLoadsForThisSize = Size / LoadSize;
133  if (LoadSequence.size() + NumLoadsForThisSize > MaxNumLoads) {
134  // Do not expand if the total number of loads is larger than what the
135  // target allows. Note that it's important that we exit before completing
136  // the expansion to avoid using a ton of memory to store the expansion for
137  // large sizes.
138  return {};
139  }
140  if (NumLoadsForThisSize > 0) {
141  for (uint64_t I = 0; I < NumLoadsForThisSize; ++I) {
142  LoadSequence.push_back({LoadSize, Offset});
143  Offset += LoadSize;
144  }
145  if (LoadSize > 1)
146  ++NumLoadsNonOneByte;
147  Size = Size % LoadSize;
148  }
149  LoadSizes = LoadSizes.drop_front();
150  }
151  return LoadSequence;
152 }
153 
155 MemCmpExpansion::computeOverlappingLoadSequence(uint64_t Size,
156  const unsigned MaxLoadSize,
157  const unsigned MaxNumLoads,
158  unsigned &NumLoadsNonOneByte) {
159  // These are already handled by the greedy approach.
160  if (Size < 2 || MaxLoadSize < 2)
161  return {};
162 
163  // We try to do as many non-overlapping loads as possible starting from the
164  // beginning.
165  const uint64_t NumNonOverlappingLoads = Size / MaxLoadSize;
166  assert(NumNonOverlappingLoads && "there must be at least one load");
167  // There remain 0 to (MaxLoadSize - 1) bytes to load, this will be done with
168  // an overlapping load.
169  Size = Size - NumNonOverlappingLoads * MaxLoadSize;
170  // Bail if we do not need an overloapping store, this is already handled by
171  // the greedy approach.
172  if (Size == 0)
173  return {};
174  // Bail if the number of loads (non-overlapping + potential overlapping one)
175  // is larger than the max allowed.
176  if ((NumNonOverlappingLoads + 1) > MaxNumLoads)
177  return {};
178 
179  // Add non-overlapping loads.
180  LoadEntryVector LoadSequence;
181  uint64_t Offset = 0;
182  for (uint64_t I = 0; I < NumNonOverlappingLoads; ++I) {
183  LoadSequence.push_back({MaxLoadSize, Offset});
184  Offset += MaxLoadSize;
185  }
186 
187  // Add the last overlapping load.
188  assert(Size > 0 && Size < MaxLoadSize && "broken invariant");
189  LoadSequence.push_back({MaxLoadSize, Offset - (MaxLoadSize - Size)});
190  NumLoadsNonOneByte = 1;
191  return LoadSequence;
192 }
193 
194 // Initialize the basic block structure required for expansion of memcmp call
195 // with given maximum load size and memcmp size parameter.
196 // This structure includes:
197 // 1. A list of load compare blocks - LoadCmpBlocks.
198 // 2. An EndBlock, split from original instruction point, which is the block to
199 // return from.
200 // 3. ResultBlock, block to branch to for early exit when a
201 // LoadCmpBlock finds a difference.
202 MemCmpExpansion::MemCmpExpansion(
203  CallInst *const CI, uint64_t Size,
205  const bool IsUsedForZeroCmp, const DataLayout &TheDataLayout)
206  : CI(CI), Size(Size), MaxLoadSize(0), NumLoadsNonOneByte(0),
207  NumLoadsPerBlockForZeroCmp(Options.NumLoadsPerBlock),
208  IsUsedForZeroCmp(IsUsedForZeroCmp), DL(TheDataLayout), Builder(CI) {
209  assert(Size > 0 && "zero blocks");
210  // Scale the max size down if the target can load more bytes than we need.
211  llvm::ArrayRef<unsigned> LoadSizes(Options.LoadSizes);
212  while (!LoadSizes.empty() && LoadSizes.front() > Size) {
213  LoadSizes = LoadSizes.drop_front();
214  }
215  assert(!LoadSizes.empty() && "cannot load Size bytes");
216  MaxLoadSize = LoadSizes.front();
217  // Compute the decomposition.
218  unsigned GreedyNumLoadsNonOneByte = 0;
219  LoadSequence = computeGreedyLoadSequence(Size, LoadSizes, Options.MaxNumLoads,
220  GreedyNumLoadsNonOneByte);
221  NumLoadsNonOneByte = GreedyNumLoadsNonOneByte;
222  assert(LoadSequence.size() <= Options.MaxNumLoads && "broken invariant");
223  // If we allow overlapping loads and the load sequence is not already optimal,
224  // use overlapping loads.
225  if (Options.AllowOverlappingLoads &&
226  (LoadSequence.empty() || LoadSequence.size() > 2)) {
227  unsigned OverlappingNumLoadsNonOneByte = 0;
228  auto OverlappingLoads = computeOverlappingLoadSequence(
229  Size, MaxLoadSize, Options.MaxNumLoads, OverlappingNumLoadsNonOneByte);
230  if (!OverlappingLoads.empty() &&
231  (LoadSequence.empty() ||
232  OverlappingLoads.size() < LoadSequence.size())) {
233  LoadSequence = OverlappingLoads;
234  NumLoadsNonOneByte = OverlappingNumLoadsNonOneByte;
235  }
236  }
237  assert(LoadSequence.size() <= Options.MaxNumLoads && "broken invariant");
238 }
239 
240 unsigned MemCmpExpansion::getNumBlocks() {
241  if (IsUsedForZeroCmp)
242  return getNumLoads() / NumLoadsPerBlockForZeroCmp +
243  (getNumLoads() % NumLoadsPerBlockForZeroCmp != 0 ? 1 : 0);
244  return getNumLoads();
245 }
246 
247 void MemCmpExpansion::createLoadCmpBlocks() {
248  for (unsigned i = 0; i < getNumBlocks(); i++) {
249  BasicBlock *BB = BasicBlock::Create(CI->getContext(), "loadbb",
250  EndBlock->getParent(), EndBlock);
251  LoadCmpBlocks.push_back(BB);
252  }
253 }
254 
255 void MemCmpExpansion::createResultBlock() {
256  ResBlock.BB = BasicBlock::Create(CI->getContext(), "res_block",
257  EndBlock->getParent(), EndBlock);
258 }
259 
260 /// Return a pointer to an element of type `LoadSizeType` at offset
261 /// `OffsetBytes`.
262 Value *MemCmpExpansion::getPtrToElementAtOffset(Value *Source,
263  Type *LoadSizeType,
264  uint64_t OffsetBytes) {
265  if (OffsetBytes > 0) {
266  auto *ByteType = Type::getInt8Ty(CI->getContext());
267  Source = Builder.CreateGEP(
268  ByteType, Builder.CreateBitCast(Source, ByteType->getPointerTo()),
269  ConstantInt::get(ByteType, OffsetBytes));
270  }
271  return Builder.CreateBitCast(Source, LoadSizeType->getPointerTo());
272 }
273 
274 // This function creates the IR instructions for loading and comparing 1 byte.
275 // It loads 1 byte from each source of the memcmp parameters with the given
276 // GEPIndex. It then subtracts the two loaded values and adds this result to the
277 // final phi node for selecting the memcmp result.
278 void MemCmpExpansion::emitLoadCompareByteBlock(unsigned BlockIndex,
279  unsigned OffsetBytes) {
280  Builder.SetInsertPoint(LoadCmpBlocks[BlockIndex]);
281  Type *LoadSizeType = Type::getInt8Ty(CI->getContext());
282  Value *Source1 =
283  getPtrToElementAtOffset(CI->getArgOperand(0), LoadSizeType, OffsetBytes);
284  Value *Source2 =
285  getPtrToElementAtOffset(CI->getArgOperand(1), LoadSizeType, OffsetBytes);
286 
287  Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
288  Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
289 
290  LoadSrc1 = Builder.CreateZExt(LoadSrc1, Type::getInt32Ty(CI->getContext()));
291  LoadSrc2 = Builder.CreateZExt(LoadSrc2, Type::getInt32Ty(CI->getContext()));
292  Value *Diff = Builder.CreateSub(LoadSrc1, LoadSrc2);
293 
294  PhiRes->addIncoming(Diff, LoadCmpBlocks[BlockIndex]);
295 
296  if (BlockIndex < (LoadCmpBlocks.size() - 1)) {
297  // Early exit branch if difference found to EndBlock. Otherwise, continue to
298  // next LoadCmpBlock,
299  Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_NE, Diff,
300  ConstantInt::get(Diff->getType(), 0));
301  BranchInst *CmpBr =
302  BranchInst::Create(EndBlock, LoadCmpBlocks[BlockIndex + 1], Cmp);
303  Builder.Insert(CmpBr);
304  } else {
305  // The last block has an unconditional branch to EndBlock.
306  BranchInst *CmpBr = BranchInst::Create(EndBlock);
307  Builder.Insert(CmpBr);
308  }
309 }
310 
311 /// Generate an equality comparison for one or more pairs of loaded values.
312 /// This is used in the case where the memcmp() call is compared equal or not
313 /// equal to zero.
314 Value *MemCmpExpansion::getCompareLoadPairs(unsigned BlockIndex,
315  unsigned &LoadIndex) {
316  assert(LoadIndex < getNumLoads() &&
317  "getCompareLoadPairs() called with no remaining loads");
318  std::vector<Value *> XorList, OrList;
319  Value *Diff = nullptr;
320 
321  const unsigned NumLoads =
322  std::min(getNumLoads() - LoadIndex, NumLoadsPerBlockForZeroCmp);
323 
324  // For a single-block expansion, start inserting before the memcmp call.
325  if (LoadCmpBlocks.empty())
326  Builder.SetInsertPoint(CI);
327  else
328  Builder.SetInsertPoint(LoadCmpBlocks[BlockIndex]);
329 
330  Value *Cmp = nullptr;
331  // If we have multiple loads per block, we need to generate a composite
332  // comparison using xor+or. The type for the combinations is the largest load
333  // type.
334  IntegerType *const MaxLoadType =
335  NumLoads == 1 ? nullptr
336  : IntegerType::get(CI->getContext(), MaxLoadSize * 8);
337  for (unsigned i = 0; i < NumLoads; ++i, ++LoadIndex) {
338  const LoadEntry &CurLoadEntry = LoadSequence[LoadIndex];
339 
340  IntegerType *LoadSizeType =
341  IntegerType::get(CI->getContext(), CurLoadEntry.LoadSize * 8);
342 
343  Value *Source1 = getPtrToElementAtOffset(CI->getArgOperand(0), LoadSizeType,
344  CurLoadEntry.Offset);
345  Value *Source2 = getPtrToElementAtOffset(CI->getArgOperand(1), LoadSizeType,
346  CurLoadEntry.Offset);
347 
348  // Get a constant or load a value for each source address.
349  Value *LoadSrc1 = nullptr;
350  if (auto *Source1C = dyn_cast<Constant>(Source1))
351  LoadSrc1 = ConstantFoldLoadFromConstPtr(Source1C, LoadSizeType, DL);
352  if (!LoadSrc1)
353  LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
354 
355  Value *LoadSrc2 = nullptr;
356  if (auto *Source2C = dyn_cast<Constant>(Source2))
357  LoadSrc2 = ConstantFoldLoadFromConstPtr(Source2C, LoadSizeType, DL);
358  if (!LoadSrc2)
359  LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
360 
361  if (NumLoads != 1) {
362  if (LoadSizeType != MaxLoadType) {
363  LoadSrc1 = Builder.CreateZExt(LoadSrc1, MaxLoadType);
364  LoadSrc2 = Builder.CreateZExt(LoadSrc2, MaxLoadType);
365  }
366  // If we have multiple loads per block, we need to generate a composite
367  // comparison using xor+or.
368  Diff = Builder.CreateXor(LoadSrc1, LoadSrc2);
369  Diff = Builder.CreateZExt(Diff, MaxLoadType);
370  XorList.push_back(Diff);
371  } else {
372  // If there's only one load per block, we just compare the loaded values.
373  Cmp = Builder.CreateICmpNE(LoadSrc1, LoadSrc2);
374  }
375  }
376 
377  auto pairWiseOr = [&](std::vector<Value *> &InList) -> std::vector<Value *> {
378  std::vector<Value *> OutList;
379  for (unsigned i = 0; i < InList.size() - 1; i = i + 2) {
380  Value *Or = Builder.CreateOr(InList[i], InList[i + 1]);
381  OutList.push_back(Or);
382  }
383  if (InList.size() % 2 != 0)
384  OutList.push_back(InList.back());
385  return OutList;
386  };
387 
388  if (!Cmp) {
389  // Pairwise OR the XOR results.
390  OrList = pairWiseOr(XorList);
391 
392  // Pairwise OR the OR results until one result left.
393  while (OrList.size() != 1) {
394  OrList = pairWiseOr(OrList);
395  }
396 
397  assert(Diff && "Failed to find comparison diff");
398  Cmp = Builder.CreateICmpNE(OrList[0], ConstantInt::get(Diff->getType(), 0));
399  }
400 
401  return Cmp;
402 }
403 
404 void MemCmpExpansion::emitLoadCompareBlockMultipleLoads(unsigned BlockIndex,
405  unsigned &LoadIndex) {
406  Value *Cmp = getCompareLoadPairs(BlockIndex, LoadIndex);
407 
408  BasicBlock *NextBB = (BlockIndex == (LoadCmpBlocks.size() - 1))
409  ? EndBlock
410  : LoadCmpBlocks[BlockIndex + 1];
411  // Early exit branch if difference found to ResultBlock. Otherwise,
412  // continue to next LoadCmpBlock or EndBlock.
413  BranchInst *CmpBr = BranchInst::Create(ResBlock.BB, NextBB, Cmp);
414  Builder.Insert(CmpBr);
415 
416  // Add a phi edge for the last LoadCmpBlock to Endblock with a value of 0
417  // since early exit to ResultBlock was not taken (no difference was found in
418  // any of the bytes).
419  if (BlockIndex == LoadCmpBlocks.size() - 1) {
420  Value *Zero = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 0);
421  PhiRes->addIncoming(Zero, LoadCmpBlocks[BlockIndex]);
422  }
423 }
424 
425 // This function creates the IR intructions for loading and comparing using the
426 // given LoadSize. It loads the number of bytes specified by LoadSize from each
427 // source of the memcmp parameters. It then does a subtract to see if there was
428 // a difference in the loaded values. If a difference is found, it branches
429 // with an early exit to the ResultBlock for calculating which source was
430 // larger. Otherwise, it falls through to the either the next LoadCmpBlock or
431 // the EndBlock if this is the last LoadCmpBlock. Loading 1 byte is handled with
432 // a special case through emitLoadCompareByteBlock. The special handling can
433 // simply subtract the loaded values and add it to the result phi node.
434 void MemCmpExpansion::emitLoadCompareBlock(unsigned BlockIndex) {
435  // There is one load per block in this case, BlockIndex == LoadIndex.
436  const LoadEntry &CurLoadEntry = LoadSequence[BlockIndex];
437 
438  if (CurLoadEntry.LoadSize == 1) {
439  MemCmpExpansion::emitLoadCompareByteBlock(BlockIndex, CurLoadEntry.Offset);
440  return;
441  }
442 
443  Type *LoadSizeType =
444  IntegerType::get(CI->getContext(), CurLoadEntry.LoadSize * 8);
445  Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);
446  assert(CurLoadEntry.LoadSize <= MaxLoadSize && "Unexpected load type");
447 
448  Builder.SetInsertPoint(LoadCmpBlocks[BlockIndex]);
449 
450  Value *Source1 = getPtrToElementAtOffset(CI->getArgOperand(0), LoadSizeType,
451  CurLoadEntry.Offset);
452  Value *Source2 = getPtrToElementAtOffset(CI->getArgOperand(1), LoadSizeType,
453  CurLoadEntry.Offset);
454 
455  // Load LoadSizeType from the base address.
456  Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
457  Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
458 
459  if (DL.isLittleEndian()) {
461  Intrinsic::bswap, LoadSizeType);
462  LoadSrc1 = Builder.CreateCall(Bswap, LoadSrc1);
463  LoadSrc2 = Builder.CreateCall(Bswap, LoadSrc2);
464  }
465 
466  if (LoadSizeType != MaxLoadType) {
467  LoadSrc1 = Builder.CreateZExt(LoadSrc1, MaxLoadType);
468  LoadSrc2 = Builder.CreateZExt(LoadSrc2, MaxLoadType);
469  }
470 
471  // Add the loaded values to the phi nodes for calculating memcmp result only
472  // if result is not used in a zero equality.
473  if (!IsUsedForZeroCmp) {
474  ResBlock.PhiSrc1->addIncoming(LoadSrc1, LoadCmpBlocks[BlockIndex]);
475  ResBlock.PhiSrc2->addIncoming(LoadSrc2, LoadCmpBlocks[BlockIndex]);
476  }
477 
478  Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_EQ, LoadSrc1, LoadSrc2);
479  BasicBlock *NextBB = (BlockIndex == (LoadCmpBlocks.size() - 1))
480  ? EndBlock
481  : LoadCmpBlocks[BlockIndex + 1];
482  // Early exit branch if difference found to ResultBlock. Otherwise, continue
483  // to next LoadCmpBlock or EndBlock.
484  BranchInst *CmpBr = BranchInst::Create(NextBB, ResBlock.BB, Cmp);
485  Builder.Insert(CmpBr);
486 
487  // Add a phi edge for the last LoadCmpBlock to Endblock with a value of 0
488  // since early exit to ResultBlock was not taken (no difference was found in
489  // any of the bytes).
490  if (BlockIndex == LoadCmpBlocks.size() - 1) {
491  Value *Zero = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 0);
492  PhiRes->addIncoming(Zero, LoadCmpBlocks[BlockIndex]);
493  }
494 }
495 
496 // This function populates the ResultBlock with a sequence to calculate the
497 // memcmp result. It compares the two loaded source values and returns -1 if
498 // src1 < src2 and 1 if src1 > src2.
499 void MemCmpExpansion::emitMemCmpResultBlock() {
500  // Special case: if memcmp result is used in a zero equality, result does not
501  // need to be calculated and can simply return 1.
502  if (IsUsedForZeroCmp) {
503  BasicBlock::iterator InsertPt = ResBlock.BB->getFirstInsertionPt();
504  Builder.SetInsertPoint(ResBlock.BB, InsertPt);
505  Value *Res = ConstantInt::get(Type::getInt32Ty(CI->getContext()), 1);
506  PhiRes->addIncoming(Res, ResBlock.BB);
507  BranchInst *NewBr = BranchInst::Create(EndBlock);
508  Builder.Insert(NewBr);
509  return;
510  }
511  BasicBlock::iterator InsertPt = ResBlock.BB->getFirstInsertionPt();
512  Builder.SetInsertPoint(ResBlock.BB, InsertPt);
513 
514  Value *Cmp = Builder.CreateICmp(ICmpInst::ICMP_ULT, ResBlock.PhiSrc1,
515  ResBlock.PhiSrc2);
516 
517  Value *Res =
518  Builder.CreateSelect(Cmp, ConstantInt::get(Builder.getInt32Ty(), -1),
519  ConstantInt::get(Builder.getInt32Ty(), 1));
520 
521  BranchInst *NewBr = BranchInst::Create(EndBlock);
522  Builder.Insert(NewBr);
523  PhiRes->addIncoming(Res, ResBlock.BB);
524 }
525 
526 void MemCmpExpansion::setupResultBlockPHINodes() {
527  Type *MaxLoadType = IntegerType::get(CI->getContext(), MaxLoadSize * 8);
528  Builder.SetInsertPoint(ResBlock.BB);
529  // Note: this assumes one load per block.
530  ResBlock.PhiSrc1 =
531  Builder.CreatePHI(MaxLoadType, NumLoadsNonOneByte, "phi.src1");
532  ResBlock.PhiSrc2 =
533  Builder.CreatePHI(MaxLoadType, NumLoadsNonOneByte, "phi.src2");
534 }
535 
536 void MemCmpExpansion::setupEndBlockPHINodes() {
537  Builder.SetInsertPoint(&EndBlock->front());
538  PhiRes = Builder.CreatePHI(Type::getInt32Ty(CI->getContext()), 2, "phi.res");
539 }
540 
541 Value *MemCmpExpansion::getMemCmpExpansionZeroCase() {
542  unsigned LoadIndex = 0;
543  // This loop populates each of the LoadCmpBlocks with the IR sequence to
544  // handle multiple loads per block.
545  for (unsigned I = 0; I < getNumBlocks(); ++I) {
546  emitLoadCompareBlockMultipleLoads(I, LoadIndex);
547  }
548 
549  emitMemCmpResultBlock();
550  return PhiRes;
551 }
552 
553 /// A memcmp expansion that compares equality with 0 and only has one block of
554 /// load and compare can bypass the compare, branch, and phi IR that is required
555 /// in the general case.
556 Value *MemCmpExpansion::getMemCmpEqZeroOneBlock() {
557  unsigned LoadIndex = 0;
558  Value *Cmp = getCompareLoadPairs(0, LoadIndex);
559  assert(LoadIndex == getNumLoads() && "some entries were not consumed");
560  return Builder.CreateZExt(Cmp, Type::getInt32Ty(CI->getContext()));
561 }
562 
563 /// A memcmp expansion that only has one block of load and compare can bypass
564 /// the compare, branch, and phi IR that is required in the general case.
565 Value *MemCmpExpansion::getMemCmpOneBlock() {
566  Type *LoadSizeType = IntegerType::get(CI->getContext(), Size * 8);
567  Value *Source1 = CI->getArgOperand(0);
568  Value *Source2 = CI->getArgOperand(1);
569 
570  // Cast source to LoadSizeType*.
571  if (Source1->getType() != LoadSizeType)
572  Source1 = Builder.CreateBitCast(Source1, LoadSizeType->getPointerTo());
573  if (Source2->getType() != LoadSizeType)
574  Source2 = Builder.CreateBitCast(Source2, LoadSizeType->getPointerTo());
575 
576  // Load LoadSizeType from the base address.
577  Value *LoadSrc1 = Builder.CreateLoad(LoadSizeType, Source1);
578  Value *LoadSrc2 = Builder.CreateLoad(LoadSizeType, Source2);
579 
580  if (DL.isLittleEndian() && Size != 1) {
582  Intrinsic::bswap, LoadSizeType);
583  LoadSrc1 = Builder.CreateCall(Bswap, LoadSrc1);
584  LoadSrc2 = Builder.CreateCall(Bswap, LoadSrc2);
585  }
586 
587  if (Size < 4) {
588  // The i8 and i16 cases don't need compares. We zext the loaded values and
589  // subtract them to get the suitable negative, zero, or positive i32 result.
590  LoadSrc1 = Builder.CreateZExt(LoadSrc1, Builder.getInt32Ty());
591  LoadSrc2 = Builder.CreateZExt(LoadSrc2, Builder.getInt32Ty());
592  return Builder.CreateSub(LoadSrc1, LoadSrc2);
593  }
594 
595  // The result of memcmp is negative, zero, or positive, so produce that by
596  // subtracting 2 extended compare bits: sub (ugt, ult).
597  // If a target prefers to use selects to get -1/0/1, they should be able
598  // to transform this later. The inverse transform (going from selects to math)
599  // may not be possible in the DAG because the selects got converted into
600  // branches before we got there.
601  Value *CmpUGT = Builder.CreateICmpUGT(LoadSrc1, LoadSrc2);
602  Value *CmpULT = Builder.CreateICmpULT(LoadSrc1, LoadSrc2);
603  Value *ZextUGT = Builder.CreateZExt(CmpUGT, Builder.getInt32Ty());
604  Value *ZextULT = Builder.CreateZExt(CmpULT, Builder.getInt32Ty());
605  return Builder.CreateSub(ZextUGT, ZextULT);
606 }
607 
608 // This function expands the memcmp call into an inline expansion and returns
609 // the memcmp result.
610 Value *MemCmpExpansion::getMemCmpExpansion() {
611  // Create the basic block framework for a multi-block expansion.
612  if (getNumBlocks() != 1) {
613  BasicBlock *StartBlock = CI->getParent();
614  EndBlock = StartBlock->splitBasicBlock(CI, "endblock");
615  setupEndBlockPHINodes();
616  createResultBlock();
617 
618  // If return value of memcmp is not used in a zero equality, we need to
619  // calculate which source was larger. The calculation requires the
620  // two loaded source values of each load compare block.
621  // These will be saved in the phi nodes created by setupResultBlockPHINodes.
622  if (!IsUsedForZeroCmp) setupResultBlockPHINodes();
623 
624  // Create the number of required load compare basic blocks.
625  createLoadCmpBlocks();
626 
627  // Update the terminator added by splitBasicBlock to branch to the first
628  // LoadCmpBlock.
629  StartBlock->getTerminator()->setSuccessor(0, LoadCmpBlocks[0]);
630  }
631 
632  Builder.SetCurrentDebugLocation(CI->getDebugLoc());
633 
634  if (IsUsedForZeroCmp)
635  return getNumBlocks() == 1 ? getMemCmpEqZeroOneBlock()
636  : getMemCmpExpansionZeroCase();
637 
638  if (getNumBlocks() == 1)
639  return getMemCmpOneBlock();
640 
641  for (unsigned I = 0; I < getNumBlocks(); ++I) {
642  emitLoadCompareBlock(I);
643  }
644 
645  emitMemCmpResultBlock();
646  return PhiRes;
647 }
648 
649 // This function checks to see if an expansion of memcmp can be generated.
650 // It checks for constant compare size that is less than the max inline size.
651 // If an expansion cannot occur, returns false to leave as a library call.
652 // Otherwise, the library call is replaced with a new IR instruction sequence.
653 /// We want to transform:
654 /// %call = call signext i32 @memcmp(i8* %0, i8* %1, i64 15)
655 /// To:
656 /// loadbb:
657 /// %0 = bitcast i32* %buffer2 to i8*
658 /// %1 = bitcast i32* %buffer1 to i8*
659 /// %2 = bitcast i8* %1 to i64*
660 /// %3 = bitcast i8* %0 to i64*
661 /// %4 = load i64, i64* %2
662 /// %5 = load i64, i64* %3
663 /// %6 = call i64 @llvm.bswap.i64(i64 %4)
664 /// %7 = call i64 @llvm.bswap.i64(i64 %5)
665 /// %8 = sub i64 %6, %7
666 /// %9 = icmp ne i64 %8, 0
667 /// br i1 %9, label %res_block, label %loadbb1
668 /// res_block: ; preds = %loadbb2,
669 /// %loadbb1, %loadbb
670 /// %phi.src1 = phi i64 [ %6, %loadbb ], [ %22, %loadbb1 ], [ %36, %loadbb2 ]
671 /// %phi.src2 = phi i64 [ %7, %loadbb ], [ %23, %loadbb1 ], [ %37, %loadbb2 ]
672 /// %10 = icmp ult i64 %phi.src1, %phi.src2
673 /// %11 = select i1 %10, i32 -1, i32 1
674 /// br label %endblock
675 /// loadbb1: ; preds = %loadbb
676 /// %12 = bitcast i32* %buffer2 to i8*
677 /// %13 = bitcast i32* %buffer1 to i8*
678 /// %14 = bitcast i8* %13 to i32*
679 /// %15 = bitcast i8* %12 to i32*
680 /// %16 = getelementptr i32, i32* %14, i32 2
681 /// %17 = getelementptr i32, i32* %15, i32 2
682 /// %18 = load i32, i32* %16
683 /// %19 = load i32, i32* %17
684 /// %20 = call i32 @llvm.bswap.i32(i32 %18)
685 /// %21 = call i32 @llvm.bswap.i32(i32 %19)
686 /// %22 = zext i32 %20 to i64
687 /// %23 = zext i32 %21 to i64
688 /// %24 = sub i64 %22, %23
689 /// %25 = icmp ne i64 %24, 0
690 /// br i1 %25, label %res_block, label %loadbb2
691 /// loadbb2: ; preds = %loadbb1
692 /// %26 = bitcast i32* %buffer2 to i8*
693 /// %27 = bitcast i32* %buffer1 to i8*
694 /// %28 = bitcast i8* %27 to i16*
695 /// %29 = bitcast i8* %26 to i16*
696 /// %30 = getelementptr i16, i16* %28, i16 6
697 /// %31 = getelementptr i16, i16* %29, i16 6
698 /// %32 = load i16, i16* %30
699 /// %33 = load i16, i16* %31
700 /// %34 = call i16 @llvm.bswap.i16(i16 %32)
701 /// %35 = call i16 @llvm.bswap.i16(i16 %33)
702 /// %36 = zext i16 %34 to i64
703 /// %37 = zext i16 %35 to i64
704 /// %38 = sub i64 %36, %37
705 /// %39 = icmp ne i64 %38, 0
706 /// br i1 %39, label %res_block, label %loadbb3
707 /// loadbb3: ; preds = %loadbb2
708 /// %40 = bitcast i32* %buffer2 to i8*
709 /// %41 = bitcast i32* %buffer1 to i8*
710 /// %42 = getelementptr i8, i8* %41, i8 14
711 /// %43 = getelementptr i8, i8* %40, i8 14
712 /// %44 = load i8, i8* %42
713 /// %45 = load i8, i8* %43
714 /// %46 = zext i8 %44 to i32
715 /// %47 = zext i8 %45 to i32
716 /// %48 = sub i32 %46, %47
717 /// br label %endblock
718 /// endblock: ; preds = %res_block,
719 /// %loadbb3
720 /// %phi.res = phi i32 [ %48, %loadbb3 ], [ %11, %res_block ]
721 /// ret i32 %phi.res
722 static bool expandMemCmp(CallInst *CI, const TargetTransformInfo *TTI,
723  const TargetLowering *TLI, const DataLayout *DL) {
724  NumMemCmpCalls++;
725 
726  // Early exit from expansion if -Oz.
727  if (CI->getFunction()->hasMinSize())
728  return false;
729 
730  // Early exit from expansion if size is not a constant.
731  ConstantInt *SizeCast = dyn_cast<ConstantInt>(CI->getArgOperand(2));
732  if (!SizeCast) {
733  NumMemCmpNotConstant++;
734  return false;
735  }
736  const uint64_t SizeVal = SizeCast->getZExtValue();
737 
738  if (SizeVal == 0) {
739  return false;
740  }
741  // TTI call to check if target would like to expand memcmp. Also, get the
742  // available load sizes.
743  const bool IsUsedForZeroCmp = isOnlyUsedInZeroEqualityComparison(CI);
744  auto Options = TTI->enableMemCmpExpansion(CI->getFunction()->hasOptSize(),
745  IsUsedForZeroCmp);
746  if (!Options) return false;
747 
748  if (MemCmpEqZeroNumLoadsPerBlock.getNumOccurrences())
750 
751  if (CI->getFunction()->hasOptSize() &&
752  MaxLoadsPerMemcmpOptSize.getNumOccurrences())
754 
755  if (!CI->getFunction()->hasOptSize() && MaxLoadsPerMemcmp.getNumOccurrences())
756  Options.MaxNumLoads = MaxLoadsPerMemcmp;
757 
758  MemCmpExpansion Expansion(CI, SizeVal, Options, IsUsedForZeroCmp, *DL);
759 
760  // Don't expand if this will require more loads than desired by the target.
761  if (Expansion.getNumLoads() == 0) {
762  NumMemCmpGreaterThanMax++;
763  return false;
764  }
765 
766  NumMemCmpInlined++;
767 
768  Value *Res = Expansion.getMemCmpExpansion();
769 
770  // Replace call with result of expansion and erase call.
771  CI->replaceAllUsesWith(Res);
772  CI->eraseFromParent();
773 
774  return true;
775 }
776 
777 
778 
779 class ExpandMemCmpPass : public FunctionPass {
780 public:
781  static char ID;
782 
783  ExpandMemCmpPass() : FunctionPass(ID) {
784  initializeExpandMemCmpPassPass(*PassRegistry::getPassRegistry());
785  }
786 
787  bool runOnFunction(Function &F) override {
788  if (skipFunction(F)) return false;
789 
790  auto *TPC = getAnalysisIfAvailable<TargetPassConfig>();
791  if (!TPC) {
792  return false;
793  }
794  const TargetLowering* TL =
795  TPC->getTM<TargetMachine>().getSubtargetImpl(F)->getTargetLowering();
796 
797  const TargetLibraryInfo *TLI =
798  &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
799  const TargetTransformInfo *TTI =
800  &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
801  auto PA = runImpl(F, TLI, TTI, TL);
802  return !PA.areAllPreserved();
803  }
804 
805 private:
806  void getAnalysisUsage(AnalysisUsage &AU) const override {
810  }
811 
813  const TargetTransformInfo *TTI,
814  const TargetLowering* TL);
815  // Returns true if a change was made.
816  bool runOnBlock(BasicBlock &BB, const TargetLibraryInfo *TLI,
817  const TargetTransformInfo *TTI, const TargetLowering* TL,
818  const DataLayout& DL);
819 };
820 
821 bool ExpandMemCmpPass::runOnBlock(
822  BasicBlock &BB, const TargetLibraryInfo *TLI,
823  const TargetTransformInfo *TTI, const TargetLowering* TL,
824  const DataLayout& DL) {
825  for (Instruction& I : BB) {
826  CallInst *CI = dyn_cast<CallInst>(&I);
827  if (!CI) {
828  continue;
829  }
830  LibFunc Func;
831  if (TLI->getLibFunc(ImmutableCallSite(CI), Func) &&
832  (Func == LibFunc_memcmp || Func == LibFunc_bcmp) &&
833  expandMemCmp(CI, TTI, TL, &DL)) {
834  return true;
835  }
836  }
837  return false;
838 }
839 
840 
842  Function &F, const TargetLibraryInfo *TLI, const TargetTransformInfo *TTI,
843  const TargetLowering* TL) {
844  const DataLayout& DL = F.getParent()->getDataLayout();
845  bool MadeChanges = false;
846  for (auto BBIt = F.begin(); BBIt != F.end();) {
847  if (runOnBlock(*BBIt, TLI, TTI, TL, DL)) {
848  MadeChanges = true;
849  // If changes were made, restart the function from the beginning, since
850  // the structure of the function was changed.
851  BBIt = F.begin();
852  } else {
853  ++BBIt;
854  }
855  }
856  return MadeChanges ? PreservedAnalyses::none() : PreservedAnalyses::all();
857 }
858 
859 } // namespace
860 
861 char ExpandMemCmpPass::ID = 0;
862 INITIALIZE_PASS_BEGIN(ExpandMemCmpPass, "expandmemcmp",
863  "Expand memcmp() to load/stores", false, false)
866 INITIALIZE_PASS_END(ExpandMemCmpPass, "expandmemcmp",
867  "Expand memcmp() to load/stores", false, false)
868 
870  return new ExpandMemCmpPass();
871 }
const T & front() const
front - Get the first element.
Definition: ArrayRef.h:151
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:67
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
Value * CreateICmp(CmpInst::Predicate P, Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2211
static bool runImpl(Function &F, TargetLibraryInfo &TLI, DominatorTree &DT)
This is the entry point for all transforms.
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI)
Value * CreateICmpNE(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2105
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Value * CreateICmpULT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2117
LoadInst * CreateLoad(Type *Ty, Value *Ptr, const char *Name)
Provided to resolve &#39;CreateLoad(Ty, Ptr, "...")&#39; correctly, instead of converting the string to &#39;bool...
Definition: IRBuilder.h:1575
Value * CreateXor(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1320
bool hasOptSize() const
Optimize this function for size (-Os) or minimum size (-Oz).
Definition: Function.h:622
iterator end()
Definition: Function.h:682
INITIALIZE_PASS_BEGIN(ExpandMemCmpPass, "expandmemcmp", "Expand memcmp() to load/stores", false, false) INITIALIZE_PASS_END(ExpandMemCmpPass
This class represents a function call, abstracting a target machine&#39;s calling convention.
FunctionPass * createExpandMemCmpPass()
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:743
STATISTIC(NumFunctions, "Total number of functions")
F(f)
const Instruction * getTerminator() const LLVM_READONLY
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:144
void setSuccessor(unsigned Idx, BasicBlock *BB)
Update the specified successor to point at the provided block.
IntegerType * getInt32Ty()
Fetch the type representing a 32-bit integer.
Definition: IRBuilder.h:383
Value * getArgOperand(unsigned i) const
Definition: InstrTypes.h:1241
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:50
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:369
PointerType * getPointerTo(unsigned AddrSpace=0) const
Return a pointer to the current type.
Definition: Type.cpp:659
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:779
void initializeExpandMemCmpPassPass(PassRegistry &)
This class defines information used to lower LLVM code to legal SelectionDAG operators that the targe...
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1963
virtual void getAnalysisUsage(AnalysisUsage &) const
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: Pass.cpp:96
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:246
expandmemcmp
static cl::opt< unsigned > MaxLoadsPerMemcmpOptSize("max-loads-per-memcmp-opt-size", cl::Hidden, cl::desc("Set maximum number of loads used in expanded memcmp for -Os/Oz"))
MemCmpExpansionOptions enableMemCmpExpansion(bool OptSize, bool IsZeroCmp) const
Value * CreateICmpUGT(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:2109
Predicate all(Predicate P0, Predicate P1)
True iff P0 and P1 are true.
bool isLittleEndian() const
Layout endianness...
Definition: DataLayout.h:232
Value * CreateSub(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:1135
void SetCurrentDebugLocation(DebugLoc L)
Set location information used by debugging information.
Definition: IRBuilder.h:156
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
Value * CreateZExt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1877
iterator begin()
Definition: Function.h:680
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:1093
void SetInsertPoint(BasicBlock *TheBB)
This specifies that created instructions should be appended to the end of the specified block...
Definition: IRBuilder.h:132
static PreservedAnalyses none()
Convenience factory function for the empty preserved set.
Definition: PassManager.h:157
static cl::opt< unsigned > MaxLoadsPerMemcmp("max-loads-per-memcmp", cl::Hidden, cl::desc("Set maximum number of loads used in expanded memcmp"))
Value * CreateOr(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:1294
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:432
Returns options for expansion of memcmp. IsZeroCmp is.
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:148
Wrapper pass for TargetTransformInfo.
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:154
* if(!EatIfPresent(lltok::kw_thread_local)) return false
ParseOptionalThreadLocal := /*empty.
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
Conditional or Unconditional Branch instruction.
Value * CreateSelect(Value *C, Value *True, Value *False, const Twine &Name="", Instruction *MDFrom=nullptr)
Definition: IRBuilder.h:2287
const Instruction & front() const
Definition: BasicBlock.h:285
Represent the analysis usage information of a pass.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:284
Class to represent integer types.
Definition: DerivedTypes.h:40
Expand memcmp() to load/stores"
const Function * getFunction() const
Return the function this instruction belongs to.
Definition: Instruction.cpp:59
Constant * ConstantFoldLoadFromConstPtr(Constant *C, Type *Ty, const DataLayout &DL)
ConstantFoldLoadFromConstPtr - Return the value that a load from C would produce if it is constant an...
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
PHINode * CreatePHI(Type *Ty, unsigned NumReservedValues, const Twine &Name="")
Definition: IRBuilder.h:2231
Value * CreateGEP(Value *Ptr, ArrayRef< Value *> IdxList, const Twine &Name="")
Definition: IRBuilder.h:1676
Iterator for intrusive lists based on ilist_node.
This is the shared class of boolean and integer constants.
Definition: Constants.h:83
This pass provides access to the codegen interfaces that are needed for IR-level transformations.
static cl::opt< unsigned > MemCmpEqZeroNumLoadsPerBlock("memcmp-num-loads-per-block", cl::Hidden, cl::init(1), cl::desc("The number of loads per basic block for inline expansion of " "memcmp that is only being compared against zero."))
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
Provides information about what library functions are available for the current target.
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:55
bool getLibFunc(StringRef funcName, LibFunc &F) const
Searches for a particular function name.
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:331
ArrayRef< T > drop_front(size_t N=1) const
Drop the first N elements of the array.
Definition: ArrayRef.h:187
Establish a view to a call site for examination.
Definition: CallSite.h:906
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:106
#define I(x, y, z)
Definition: MD5.cpp:58
bool hasMinSize() const
Optimize this function for minimum size (-Oz).
Definition: Function.h:619
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:332
uint32_t Size
Definition: Profile.cpp:46
CallInst * CreateCall(FunctionType *FTy, Value *Callee, ArrayRef< Value *> Args=None, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:2239
BasicBlock * splitBasicBlock(iterator I, const Twine &BBName="")
Split the basic block into two basic blocks at the specified instruction.
Definition: BasicBlock.cpp:414
InstTy * Insert(InstTy *I, const Twine &Name="") const
Insert and return the specified instruction.
Definition: IRBuilder.h:830
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:575
LLVM Value Representation.
Definition: Value.h:74
virtual bool runOnFunction(Function &F)=0
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
Primary interface to the complete machine description for the target machine.
Definition: TargetMachine.h:65
bool skipFunction(const Function &F) const
Optional passes call this function to check whether the pass should be skipped.
Definition: Pass.cpp:166
This pass exposes codegen information to IR-level passes.
hexagon widen stores
bool empty() const
empty - Check if the array is empty.
Definition: ArrayRef.h:143
This file describes how to lower LLVM code to machine code.
const BasicBlock * getParent() const
Definition: Instruction.h:66