LLVM  9.0.0svn
SROA.cpp
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1 //===- SROA.cpp - Scalar Replacement Of Aggregates ------------------------===//
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 /// \file
10 /// This transformation implements the well known scalar replacement of
11 /// aggregates transformation. It tries to identify promotable elements of an
12 /// aggregate alloca, and promote them to registers. It will also try to
13 /// convert uses of an element (or set of elements) of an alloca into a vector
14 /// or bitfield-style integer scalar if appropriate.
15 ///
16 /// It works to do this with minimal slicing of the alloca so that regions
17 /// which are merely transferred in and out of external memory remain unchanged
18 /// and are not decomposed to scalar code.
19 ///
20 /// Because this also performs alloca promotion, it can be thought of as also
21 /// serving the purpose of SSA formation. The algorithm iterates on the
22 /// function until all opportunities for promotion have been realized.
23 ///
24 //===----------------------------------------------------------------------===//
25 
27 #include "llvm/ADT/APInt.h"
28 #include "llvm/ADT/ArrayRef.h"
29 #include "llvm/ADT/DenseMap.h"
31 #include "llvm/ADT/STLExtras.h"
32 #include "llvm/ADT/SetVector.h"
34 #include "llvm/ADT/SmallPtrSet.h"
35 #include "llvm/ADT/SmallVector.h"
36 #include "llvm/ADT/Statistic.h"
37 #include "llvm/ADT/StringRef.h"
38 #include "llvm/ADT/Twine.h"
39 #include "llvm/ADT/iterator.h"
43 #include "llvm/Analysis/Loads.h"
46 #include "llvm/Config/llvm-config.h"
47 #include "llvm/IR/BasicBlock.h"
48 #include "llvm/IR/Constant.h"
49 #include "llvm/IR/ConstantFolder.h"
50 #include "llvm/IR/Constants.h"
51 #include "llvm/IR/DIBuilder.h"
52 #include "llvm/IR/DataLayout.h"
54 #include "llvm/IR/DerivedTypes.h"
55 #include "llvm/IR/Dominators.h"
56 #include "llvm/IR/Function.h"
58 #include "llvm/IR/GlobalAlias.h"
59 #include "llvm/IR/IRBuilder.h"
60 #include "llvm/IR/InstVisitor.h"
61 #include "llvm/IR/InstrTypes.h"
62 #include "llvm/IR/Instruction.h"
63 #include "llvm/IR/Instructions.h"
64 #include "llvm/IR/IntrinsicInst.h"
65 #include "llvm/IR/Intrinsics.h"
66 #include "llvm/IR/LLVMContext.h"
67 #include "llvm/IR/Metadata.h"
68 #include "llvm/IR/Module.h"
69 #include "llvm/IR/Operator.h"
70 #include "llvm/IR/PassManager.h"
71 #include "llvm/IR/Type.h"
72 #include "llvm/IR/Use.h"
73 #include "llvm/IR/User.h"
74 #include "llvm/IR/Value.h"
75 #include "llvm/Pass.h"
76 #include "llvm/Support/Casting.h"
78 #include "llvm/Support/Compiler.h"
79 #include "llvm/Support/Debug.h"
83 #include "llvm/Transforms/Scalar.h"
85 #include <algorithm>
86 #include <cassert>
87 #include <chrono>
88 #include <cstddef>
89 #include <cstdint>
90 #include <cstring>
91 #include <iterator>
92 #include <string>
93 #include <tuple>
94 #include <utility>
95 #include <vector>
96 
97 #ifndef NDEBUG
98 // We only use this for a debug check.
99 #include <random>
100 #endif
101 
102 using namespace llvm;
103 using namespace llvm::sroa;
104 
105 #define DEBUG_TYPE "sroa"
106 
107 STATISTIC(NumAllocasAnalyzed, "Number of allocas analyzed for replacement");
108 STATISTIC(NumAllocaPartitions, "Number of alloca partitions formed");
109 STATISTIC(MaxPartitionsPerAlloca, "Maximum number of partitions per alloca");
110 STATISTIC(NumAllocaPartitionUses, "Number of alloca partition uses rewritten");
111 STATISTIC(MaxUsesPerAllocaPartition, "Maximum number of uses of a partition");
112 STATISTIC(NumNewAllocas, "Number of new, smaller allocas introduced");
113 STATISTIC(NumPromoted, "Number of allocas promoted to SSA values");
114 STATISTIC(NumLoadsSpeculated, "Number of loads speculated to allow promotion");
115 STATISTIC(NumDeleted, "Number of instructions deleted");
116 STATISTIC(NumVectorized, "Number of vectorized aggregates");
117 
118 /// Hidden option to enable randomly shuffling the slices to help uncover
119 /// instability in their order.
120 static cl::opt<bool> SROARandomShuffleSlices("sroa-random-shuffle-slices",
121  cl::init(false), cl::Hidden);
122 
123 /// Hidden option to experiment with completely strict handling of inbounds
124 /// GEPs.
125 static cl::opt<bool> SROAStrictInbounds("sroa-strict-inbounds", cl::init(false),
126  cl::Hidden);
127 
128 namespace {
129 
130 /// A custom IRBuilder inserter which prefixes all names, but only in
131 /// Assert builds.
132 class IRBuilderPrefixedInserter : public IRBuilderDefaultInserter {
133  std::string Prefix;
134 
135  const Twine getNameWithPrefix(const Twine &Name) const {
136  return Name.isTriviallyEmpty() ? Name : Prefix + Name;
137  }
138 
139 public:
140  void SetNamePrefix(const Twine &P) { Prefix = P.str(); }
141 
142 protected:
143  void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB,
144  BasicBlock::iterator InsertPt) const {
145  IRBuilderDefaultInserter::InsertHelper(I, getNameWithPrefix(Name), BB,
146  InsertPt);
147  }
148 };
149 
150 /// Provide a type for IRBuilder that drops names in release builds.
152 
153 /// A used slice of an alloca.
154 ///
155 /// This structure represents a slice of an alloca used by some instruction. It
156 /// stores both the begin and end offsets of this use, a pointer to the use
157 /// itself, and a flag indicating whether we can classify the use as splittable
158 /// or not when forming partitions of the alloca.
159 class Slice {
160  /// The beginning offset of the range.
161  uint64_t BeginOffset = 0;
162 
163  /// The ending offset, not included in the range.
164  uint64_t EndOffset = 0;
165 
166  /// Storage for both the use of this slice and whether it can be
167  /// split.
168  PointerIntPair<Use *, 1, bool> UseAndIsSplittable;
169 
170 public:
171  Slice() = default;
172 
173  Slice(uint64_t BeginOffset, uint64_t EndOffset, Use *U, bool IsSplittable)
174  : BeginOffset(BeginOffset), EndOffset(EndOffset),
175  UseAndIsSplittable(U, IsSplittable) {}
176 
177  uint64_t beginOffset() const { return BeginOffset; }
178  uint64_t endOffset() const { return EndOffset; }
179 
180  bool isSplittable() const { return UseAndIsSplittable.getInt(); }
181  void makeUnsplittable() { UseAndIsSplittable.setInt(false); }
182 
183  Use *getUse() const { return UseAndIsSplittable.getPointer(); }
184 
185  bool isDead() const { return getUse() == nullptr; }
186  void kill() { UseAndIsSplittable.setPointer(nullptr); }
187 
188  /// Support for ordering ranges.
189  ///
190  /// This provides an ordering over ranges such that start offsets are
191  /// always increasing, and within equal start offsets, the end offsets are
192  /// decreasing. Thus the spanning range comes first in a cluster with the
193  /// same start position.
194  bool operator<(const Slice &RHS) const {
195  if (beginOffset() < RHS.beginOffset())
196  return true;
197  if (beginOffset() > RHS.beginOffset())
198  return false;
199  if (isSplittable() != RHS.isSplittable())
200  return !isSplittable();
201  if (endOffset() > RHS.endOffset())
202  return true;
203  return false;
204  }
205 
206  /// Support comparison with a single offset to allow binary searches.
207  friend LLVM_ATTRIBUTE_UNUSED bool operator<(const Slice &LHS,
208  uint64_t RHSOffset) {
209  return LHS.beginOffset() < RHSOffset;
210  }
211  friend LLVM_ATTRIBUTE_UNUSED bool operator<(uint64_t LHSOffset,
212  const Slice &RHS) {
213  return LHSOffset < RHS.beginOffset();
214  }
215 
216  bool operator==(const Slice &RHS) const {
217  return isSplittable() == RHS.isSplittable() &&
218  beginOffset() == RHS.beginOffset() && endOffset() == RHS.endOffset();
219  }
220  bool operator!=(const Slice &RHS) const { return !operator==(RHS); }
221 };
222 
223 } // end anonymous namespace
224 
225 namespace llvm {
226 
227 template <typename T> struct isPodLike;
228 template <> struct isPodLike<Slice> { static const bool value = true; };
229 
230 } // end namespace llvm
231 
232 /// Representation of the alloca slices.
233 ///
234 /// This class represents the slices of an alloca which are formed by its
235 /// various uses. If a pointer escapes, we can't fully build a representation
236 /// for the slices used and we reflect that in this structure. The uses are
237 /// stored, sorted by increasing beginning offset and with unsplittable slices
238 /// starting at a particular offset before splittable slices.
240 public:
241  /// Construct the slices of a particular alloca.
242  AllocaSlices(const DataLayout &DL, AllocaInst &AI);
243 
244  /// Test whether a pointer to the allocation escapes our analysis.
245  ///
246  /// If this is true, the slices are never fully built and should be
247  /// ignored.
248  bool isEscaped() const { return PointerEscapingInstr; }
249 
250  /// Support for iterating over the slices.
251  /// @{
254 
255  iterator begin() { return Slices.begin(); }
256  iterator end() { return Slices.end(); }
257 
260 
261  const_iterator begin() const { return Slices.begin(); }
262  const_iterator end() const { return Slices.end(); }
263  /// @}
264 
265  /// Erase a range of slices.
266  void erase(iterator Start, iterator Stop) { Slices.erase(Start, Stop); }
267 
268  /// Insert new slices for this alloca.
269  ///
270  /// This moves the slices into the alloca's slices collection, and re-sorts
271  /// everything so that the usual ordering properties of the alloca's slices
272  /// hold.
273  void insert(ArrayRef<Slice> NewSlices) {
274  int OldSize = Slices.size();
275  Slices.append(NewSlices.begin(), NewSlices.end());
276  auto SliceI = Slices.begin() + OldSize;
277  llvm::sort(SliceI, Slices.end());
278  std::inplace_merge(Slices.begin(), SliceI, Slices.end());
279  }
280 
281  // Forward declare the iterator and range accessor for walking the
282  // partitions.
283  class partition_iterator;
285 
286  /// Access the dead users for this alloca.
287  ArrayRef<Instruction *> getDeadUsers() const { return DeadUsers; }
288 
289  /// Access the dead operands referring to this alloca.
290  ///
291  /// These are operands which have cannot actually be used to refer to the
292  /// alloca as they are outside its range and the user doesn't correct for
293  /// that. These mostly consist of PHI node inputs and the like which we just
294  /// need to replace with undef.
295  ArrayRef<Use *> getDeadOperands() const { return DeadOperands; }
296 
297 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
298  void print(raw_ostream &OS, const_iterator I, StringRef Indent = " ") const;
299  void printSlice(raw_ostream &OS, const_iterator I,
300  StringRef Indent = " ") const;
301  void printUse(raw_ostream &OS, const_iterator I,
302  StringRef Indent = " ") const;
303  void print(raw_ostream &OS) const;
304  void dump(const_iterator I) const;
305  void dump() const;
306 #endif
307 
308 private:
309  template <typename DerivedT, typename RetT = void> class BuilderBase;
310  class SliceBuilder;
311 
312  friend class AllocaSlices::SliceBuilder;
313 
314 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
315  /// Handle to alloca instruction to simplify method interfaces.
316  AllocaInst &AI;
317 #endif
318 
319  /// The instruction responsible for this alloca not having a known set
320  /// of slices.
321  ///
322  /// When an instruction (potentially) escapes the pointer to the alloca, we
323  /// store a pointer to that here and abort trying to form slices of the
324  /// alloca. This will be null if the alloca slices are analyzed successfully.
325  Instruction *PointerEscapingInstr;
326 
327  /// The slices of the alloca.
328  ///
329  /// We store a vector of the slices formed by uses of the alloca here. This
330  /// vector is sorted by increasing begin offset, and then the unsplittable
331  /// slices before the splittable ones. See the Slice inner class for more
332  /// details.
333  SmallVector<Slice, 8> Slices;
334 
335  /// Instructions which will become dead if we rewrite the alloca.
336  ///
337  /// Note that these are not separated by slice. This is because we expect an
338  /// alloca to be completely rewritten or not rewritten at all. If rewritten,
339  /// all these instructions can simply be removed and replaced with undef as
340  /// they come from outside of the allocated space.
342 
343  /// Operands which will become dead if we rewrite the alloca.
344  ///
345  /// These are operands that in their particular use can be replaced with
346  /// undef when we rewrite the alloca. These show up in out-of-bounds inputs
347  /// to PHI nodes and the like. They aren't entirely dead (there might be
348  /// a GEP back into the bounds using it elsewhere) and nor is the PHI, but we
349  /// want to swap this particular input for undef to simplify the use lists of
350  /// the alloca.
351  SmallVector<Use *, 8> DeadOperands;
352 };
353 
354 /// A partition of the slices.
355 ///
356 /// An ephemeral representation for a range of slices which can be viewed as
357 /// a partition of the alloca. This range represents a span of the alloca's
358 /// memory which cannot be split, and provides access to all of the slices
359 /// overlapping some part of the partition.
360 ///
361 /// Objects of this type are produced by traversing the alloca's slices, but
362 /// are only ephemeral and not persistent.
364 private:
365  friend class AllocaSlices;
367 
368  using iterator = AllocaSlices::iterator;
369 
370  /// The beginning and ending offsets of the alloca for this
371  /// partition.
372  uint64_t BeginOffset, EndOffset;
373 
374  /// The start and end iterators of this partition.
375  iterator SI, SJ;
376 
377  /// A collection of split slice tails overlapping the partition.
378  SmallVector<Slice *, 4> SplitTails;
379 
380  /// Raw constructor builds an empty partition starting and ending at
381  /// the given iterator.
382  Partition(iterator SI) : SI(SI), SJ(SI) {}
383 
384 public:
385  /// The start offset of this partition.
386  ///
387  /// All of the contained slices start at or after this offset.
388  uint64_t beginOffset() const { return BeginOffset; }
389 
390  /// The end offset of this partition.
391  ///
392  /// All of the contained slices end at or before this offset.
393  uint64_t endOffset() const { return EndOffset; }
394 
395  /// The size of the partition.
396  ///
397  /// Note that this can never be zero.
398  uint64_t size() const {
399  assert(BeginOffset < EndOffset && "Partitions must span some bytes!");
400  return EndOffset - BeginOffset;
401  }
402 
403  /// Test whether this partition contains no slices, and merely spans
404  /// a region occupied by split slices.
405  bool empty() const { return SI == SJ; }
406 
407  /// \name Iterate slices that start within the partition.
408  /// These may be splittable or unsplittable. They have a begin offset >= the
409  /// partition begin offset.
410  /// @{
411  // FIXME: We should probably define a "concat_iterator" helper and use that
412  // to stitch together pointee_iterators over the split tails and the
413  // contiguous iterators of the partition. That would give a much nicer
414  // interface here. We could then additionally expose filtered iterators for
415  // split, unsplit, and unsplittable splices based on the usage patterns.
416  iterator begin() const { return SI; }
417  iterator end() const { return SJ; }
418  /// @}
419 
420  /// Get the sequence of split slice tails.
421  ///
422  /// These tails are of slices which start before this partition but are
423  /// split and overlap into the partition. We accumulate these while forming
424  /// partitions.
425  ArrayRef<Slice *> splitSliceTails() const { return SplitTails; }
426 };
427 
428 /// An iterator over partitions of the alloca's slices.
429 ///
430 /// This iterator implements the core algorithm for partitioning the alloca's
431 /// slices. It is a forward iterator as we don't support backtracking for
432 /// efficiency reasons, and re-use a single storage area to maintain the
433 /// current set of split slices.
434 ///
435 /// It is templated on the slice iterator type to use so that it can operate
436 /// with either const or non-const slice iterators.
438  : public iterator_facade_base<partition_iterator, std::forward_iterator_tag,
439  Partition> {
440  friend class AllocaSlices;
441 
442  /// Most of the state for walking the partitions is held in a class
443  /// with a nice interface for examining them.
444  Partition P;
445 
446  /// We need to keep the end of the slices to know when to stop.
448 
449  /// We also need to keep track of the maximum split end offset seen.
450  /// FIXME: Do we really?
451  uint64_t MaxSplitSliceEndOffset = 0;
452 
453  /// Sets the partition to be empty at given iterator, and sets the
454  /// end iterator.
456  : P(SI), SE(SE) {
457  // If not already at the end, advance our state to form the initial
458  // partition.
459  if (SI != SE)
460  advance();
461  }
462 
463  /// Advance the iterator to the next partition.
464  ///
465  /// Requires that the iterator not be at the end of the slices.
466  void advance() {
467  assert((P.SI != SE || !P.SplitTails.empty()) &&
468  "Cannot advance past the end of the slices!");
469 
470  // Clear out any split uses which have ended.
471  if (!P.SplitTails.empty()) {
472  if (P.EndOffset >= MaxSplitSliceEndOffset) {
473  // If we've finished all splits, this is easy.
474  P.SplitTails.clear();
475  MaxSplitSliceEndOffset = 0;
476  } else {
477  // Remove the uses which have ended in the prior partition. This
478  // cannot change the max split slice end because we just checked that
479  // the prior partition ended prior to that max.
480  P.SplitTails.erase(llvm::remove_if(P.SplitTails,
481  [&](Slice *S) {
482  return S->endOffset() <=
483  P.EndOffset;
484  }),
485  P.SplitTails.end());
486  assert(llvm::any_of(P.SplitTails,
487  [&](Slice *S) {
488  return S->endOffset() == MaxSplitSliceEndOffset;
489  }) &&
490  "Could not find the current max split slice offset!");
491  assert(llvm::all_of(P.SplitTails,
492  [&](Slice *S) {
493  return S->endOffset() <= MaxSplitSliceEndOffset;
494  }) &&
495  "Max split slice end offset is not actually the max!");
496  }
497  }
498 
499  // If P.SI is already at the end, then we've cleared the split tail and
500  // now have an end iterator.
501  if (P.SI == SE) {
502  assert(P.SplitTails.empty() && "Failed to clear the split slices!");
503  return;
504  }
505 
506  // If we had a non-empty partition previously, set up the state for
507  // subsequent partitions.
508  if (P.SI != P.SJ) {
509  // Accumulate all the splittable slices which started in the old
510  // partition into the split list.
511  for (Slice &S : P)
512  if (S.isSplittable() && S.endOffset() > P.EndOffset) {
513  P.SplitTails.push_back(&S);
514  MaxSplitSliceEndOffset =
515  std::max(S.endOffset(), MaxSplitSliceEndOffset);
516  }
517 
518  // Start from the end of the previous partition.
519  P.SI = P.SJ;
520 
521  // If P.SI is now at the end, we at most have a tail of split slices.
522  if (P.SI == SE) {
523  P.BeginOffset = P.EndOffset;
524  P.EndOffset = MaxSplitSliceEndOffset;
525  return;
526  }
527 
528  // If the we have split slices and the next slice is after a gap and is
529  // not splittable immediately form an empty partition for the split
530  // slices up until the next slice begins.
531  if (!P.SplitTails.empty() && P.SI->beginOffset() != P.EndOffset &&
532  !P.SI->isSplittable()) {
533  P.BeginOffset = P.EndOffset;
534  P.EndOffset = P.SI->beginOffset();
535  return;
536  }
537  }
538 
539  // OK, we need to consume new slices. Set the end offset based on the
540  // current slice, and step SJ past it. The beginning offset of the
541  // partition is the beginning offset of the next slice unless we have
542  // pre-existing split slices that are continuing, in which case we begin
543  // at the prior end offset.
544  P.BeginOffset = P.SplitTails.empty() ? P.SI->beginOffset() : P.EndOffset;
545  P.EndOffset = P.SI->endOffset();
546  ++P.SJ;
547 
548  // There are two strategies to form a partition based on whether the
549  // partition starts with an unsplittable slice or a splittable slice.
550  if (!P.SI->isSplittable()) {
551  // When we're forming an unsplittable region, it must always start at
552  // the first slice and will extend through its end.
553  assert(P.BeginOffset == P.SI->beginOffset());
554 
555  // Form a partition including all of the overlapping slices with this
556  // unsplittable slice.
557  while (P.SJ != SE && P.SJ->beginOffset() < P.EndOffset) {
558  if (!P.SJ->isSplittable())
559  P.EndOffset = std::max(P.EndOffset, P.SJ->endOffset());
560  ++P.SJ;
561  }
562 
563  // We have a partition across a set of overlapping unsplittable
564  // partitions.
565  return;
566  }
567 
568  // If we're starting with a splittable slice, then we need to form
569  // a synthetic partition spanning it and any other overlapping splittable
570  // splices.
571  assert(P.SI->isSplittable() && "Forming a splittable partition!");
572 
573  // Collect all of the overlapping splittable slices.
574  while (P.SJ != SE && P.SJ->beginOffset() < P.EndOffset &&
575  P.SJ->isSplittable()) {
576  P.EndOffset = std::max(P.EndOffset, P.SJ->endOffset());
577  ++P.SJ;
578  }
579 
580  // Back upiP.EndOffset if we ended the span early when encountering an
581  // unsplittable slice. This synthesizes the early end offset of
582  // a partition spanning only splittable slices.
583  if (P.SJ != SE && P.SJ->beginOffset() < P.EndOffset) {
584  assert(!P.SJ->isSplittable());
585  P.EndOffset = P.SJ->beginOffset();
586  }
587  }
588 
589 public:
590  bool operator==(const partition_iterator &RHS) const {
591  assert(SE == RHS.SE &&
592  "End iterators don't match between compared partition iterators!");
593 
594  // The observed positions of partitions is marked by the P.SI iterator and
595  // the emptiness of the split slices. The latter is only relevant when
596  // P.SI == SE, as the end iterator will additionally have an empty split
597  // slices list, but the prior may have the same P.SI and a tail of split
598  // slices.
599  if (P.SI == RHS.P.SI && P.SplitTails.empty() == RHS.P.SplitTails.empty()) {
600  assert(P.SJ == RHS.P.SJ &&
601  "Same set of slices formed two different sized partitions!");
602  assert(P.SplitTails.size() == RHS.P.SplitTails.size() &&
603  "Same slice position with differently sized non-empty split "
604  "slice tails!");
605  return true;
606  }
607  return false;
608  }
609 
611  advance();
612  return *this;
613  }
614 
615  Partition &operator*() { return P; }
616 };
617 
618 /// A forward range over the partitions of the alloca's slices.
619 ///
620 /// This accesses an iterator range over the partitions of the alloca's
621 /// slices. It computes these partitions on the fly based on the overlapping
622 /// offsets of the slices and the ability to split them. It will visit "empty"
623 /// partitions to cover regions of the alloca only accessed via split
624 /// slices.
626  return make_range(partition_iterator(begin(), end()),
627  partition_iterator(end(), end()));
628 }
629 
631  // If the condition being selected on is a constant or the same value is
632  // being selected between, fold the select. Yes this does (rarely) happen
633  // early on.
634  if (ConstantInt *CI = dyn_cast<ConstantInt>(SI.getCondition()))
635  return SI.getOperand(1 + CI->isZero());
636  if (SI.getOperand(1) == SI.getOperand(2))
637  return SI.getOperand(1);
638 
639  return nullptr;
640 }
641 
642 /// A helper that folds a PHI node or a select.
644  if (PHINode *PN = dyn_cast<PHINode>(&I)) {
645  // If PN merges together the same value, return that value.
646  return PN->hasConstantValue();
647  }
648  return foldSelectInst(cast<SelectInst>(I));
649 }
650 
651 /// Builder for the alloca slices.
652 ///
653 /// This class builds a set of alloca slices by recursively visiting the uses
654 /// of an alloca and making a slice for each load and store at each offset.
655 class AllocaSlices::SliceBuilder : public PtrUseVisitor<SliceBuilder> {
657  friend class InstVisitor<SliceBuilder>;
658 
660 
661  const uint64_t AllocSize;
662  AllocaSlices &AS;
663 
664  SmallDenseMap<Instruction *, unsigned> MemTransferSliceMap;
666 
667  /// Set to de-duplicate dead instructions found in the use walk.
668  SmallPtrSet<Instruction *, 4> VisitedDeadInsts;
669 
670 public:
673  AllocSize(DL.getTypeAllocSize(AI.getAllocatedType())), AS(AS) {}
674 
675 private:
676  void markAsDead(Instruction &I) {
677  if (VisitedDeadInsts.insert(&I).second)
678  AS.DeadUsers.push_back(&I);
679  }
680 
681  void insertUse(Instruction &I, const APInt &Offset, uint64_t Size,
682  bool IsSplittable = false) {
683  // Completely skip uses which have a zero size or start either before or
684  // past the end of the allocation.
685  if (Size == 0 || Offset.uge(AllocSize)) {
686  LLVM_DEBUG(dbgs() << "WARNING: Ignoring " << Size << " byte use @"
687  << Offset
688  << " which has zero size or starts outside of the "
689  << AllocSize << " byte alloca:\n"
690  << " alloca: " << AS.AI << "\n"
691  << " use: " << I << "\n");
692  return markAsDead(I);
693  }
694 
695  uint64_t BeginOffset = Offset.getZExtValue();
696  uint64_t EndOffset = BeginOffset + Size;
697 
698  // Clamp the end offset to the end of the allocation. Note that this is
699  // formulated to handle even the case where "BeginOffset + Size" overflows.
700  // This may appear superficially to be something we could ignore entirely,
701  // but that is not so! There may be widened loads or PHI-node uses where
702  // some instructions are dead but not others. We can't completely ignore
703  // them, and so have to record at least the information here.
704  assert(AllocSize >= BeginOffset); // Established above.
705  if (Size > AllocSize - BeginOffset) {
706  LLVM_DEBUG(dbgs() << "WARNING: Clamping a " << Size << " byte use @"
707  << Offset << " to remain within the " << AllocSize
708  << " byte alloca:\n"
709  << " alloca: " << AS.AI << "\n"
710  << " use: " << I << "\n");
711  EndOffset = AllocSize;
712  }
713 
714  AS.Slices.push_back(Slice(BeginOffset, EndOffset, U, IsSplittable));
715  }
716 
717  void visitBitCastInst(BitCastInst &BC) {
718  if (BC.use_empty())
719  return markAsDead(BC);
720 
721  return Base::visitBitCastInst(BC);
722  }
723 
724  void visitGetElementPtrInst(GetElementPtrInst &GEPI) {
725  if (GEPI.use_empty())
726  return markAsDead(GEPI);
727 
728  if (SROAStrictInbounds && GEPI.isInBounds()) {
729  // FIXME: This is a manually un-factored variant of the basic code inside
730  // of GEPs with checking of the inbounds invariant specified in the
731  // langref in a very strict sense. If we ever want to enable
732  // SROAStrictInbounds, this code should be factored cleanly into
733  // PtrUseVisitor, but it is easier to experiment with SROAStrictInbounds
734  // by writing out the code here where we have the underlying allocation
735  // size readily available.
736  APInt GEPOffset = Offset;
737  const DataLayout &DL = GEPI.getModule()->getDataLayout();
738  for (gep_type_iterator GTI = gep_type_begin(GEPI),
739  GTE = gep_type_end(GEPI);
740  GTI != GTE; ++GTI) {
741  ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
742  if (!OpC)
743  break;
744 
745  // Handle a struct index, which adds its field offset to the pointer.
746  if (StructType *STy = GTI.getStructTypeOrNull()) {
747  unsigned ElementIdx = OpC->getZExtValue();
748  const StructLayout *SL = DL.getStructLayout(STy);
749  GEPOffset +=
750  APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx));
751  } else {
752  // For array or vector indices, scale the index by the size of the
753  // type.
754  APInt Index = OpC->getValue().sextOrTrunc(Offset.getBitWidth());
755  GEPOffset += Index * APInt(Offset.getBitWidth(),
756  DL.getTypeAllocSize(GTI.getIndexedType()));
757  }
758 
759  // If this index has computed an intermediate pointer which is not
760  // inbounds, then the result of the GEP is a poison value and we can
761  // delete it and all uses.
762  if (GEPOffset.ugt(AllocSize))
763  return markAsDead(GEPI);
764  }
765  }
766 
767  return Base::visitGetElementPtrInst(GEPI);
768  }
769 
770  void handleLoadOrStore(Type *Ty, Instruction &I, const APInt &Offset,
771  uint64_t Size, bool IsVolatile) {
772  // We allow splitting of non-volatile loads and stores where the type is an
773  // integer type. These may be used to implement 'memcpy' or other "transfer
774  // of bits" patterns.
775  bool IsSplittable = Ty->isIntegerTy() && !IsVolatile;
776 
777  insertUse(I, Offset, Size, IsSplittable);
778  }
779 
780  void visitLoadInst(LoadInst &LI) {
781  assert((!LI.isSimple() || LI.getType()->isSingleValueType()) &&
782  "All simple FCA loads should have been pre-split");
783 
784  if (!IsOffsetKnown)
785  return PI.setAborted(&LI);
786 
787  const DataLayout &DL = LI.getModule()->getDataLayout();
788  uint64_t Size = DL.getTypeStoreSize(LI.getType());
789  return handleLoadOrStore(LI.getType(), LI, Offset, Size, LI.isVolatile());
790  }
791 
792  void visitStoreInst(StoreInst &SI) {
793  Value *ValOp = SI.getValueOperand();
794  if (ValOp == *U)
795  return PI.setEscapedAndAborted(&SI);
796  if (!IsOffsetKnown)
797  return PI.setAborted(&SI);
798 
799  const DataLayout &DL = SI.getModule()->getDataLayout();
800  uint64_t Size = DL.getTypeStoreSize(ValOp->getType());
801 
802  // If this memory access can be shown to *statically* extend outside the
803  // bounds of the allocation, it's behavior is undefined, so simply
804  // ignore it. Note that this is more strict than the generic clamping
805  // behavior of insertUse. We also try to handle cases which might run the
806  // risk of overflow.
807  // FIXME: We should instead consider the pointer to have escaped if this
808  // function is being instrumented for addressing bugs or race conditions.
809  if (Size > AllocSize || Offset.ugt(AllocSize - Size)) {
810  LLVM_DEBUG(dbgs() << "WARNING: Ignoring " << Size << " byte store @"
811  << Offset << " which extends past the end of the "
812  << AllocSize << " byte alloca:\n"
813  << " alloca: " << AS.AI << "\n"
814  << " use: " << SI << "\n");
815  return markAsDead(SI);
816  }
817 
818  assert((!SI.isSimple() || ValOp->getType()->isSingleValueType()) &&
819  "All simple FCA stores should have been pre-split");
820  handleLoadOrStore(ValOp->getType(), SI, Offset, Size, SI.isVolatile());
821  }
822 
823  void visitMemSetInst(MemSetInst &II) {
824  assert(II.getRawDest() == *U && "Pointer use is not the destination?");
825  ConstantInt *Length = dyn_cast<ConstantInt>(II.getLength());
826  if ((Length && Length->getValue() == 0) ||
827  (IsOffsetKnown && Offset.uge(AllocSize)))
828  // Zero-length mem transfer intrinsics can be ignored entirely.
829  return markAsDead(II);
830 
831  if (!IsOffsetKnown)
832  return PI.setAborted(&II);
833 
834  insertUse(II, Offset, Length ? Length->getLimitedValue()
835  : AllocSize - Offset.getLimitedValue(),
836  (bool)Length);
837  }
838 
839  void visitMemTransferInst(MemTransferInst &II) {
840  ConstantInt *Length = dyn_cast<ConstantInt>(II.getLength());
841  if (Length && Length->getValue() == 0)
842  // Zero-length mem transfer intrinsics can be ignored entirely.
843  return markAsDead(II);
844 
845  // Because we can visit these intrinsics twice, also check to see if the
846  // first time marked this instruction as dead. If so, skip it.
847  if (VisitedDeadInsts.count(&II))
848  return;
849 
850  if (!IsOffsetKnown)
851  return PI.setAborted(&II);
852 
853  // This side of the transfer is completely out-of-bounds, and so we can
854  // nuke the entire transfer. However, we also need to nuke the other side
855  // if already added to our partitions.
856  // FIXME: Yet another place we really should bypass this when
857  // instrumenting for ASan.
858  if (Offset.uge(AllocSize)) {
860  MemTransferSliceMap.find(&II);
861  if (MTPI != MemTransferSliceMap.end())
862  AS.Slices[MTPI->second].kill();
863  return markAsDead(II);
864  }
865 
866  uint64_t RawOffset = Offset.getLimitedValue();
867  uint64_t Size = Length ? Length->getLimitedValue() : AllocSize - RawOffset;
868 
869  // Check for the special case where the same exact value is used for both
870  // source and dest.
871  if (*U == II.getRawDest() && *U == II.getRawSource()) {
872  // For non-volatile transfers this is a no-op.
873  if (!II.isVolatile())
874  return markAsDead(II);
875 
876  return insertUse(II, Offset, Size, /*IsSplittable=*/false);
877  }
878 
879  // If we have seen both source and destination for a mem transfer, then
880  // they both point to the same alloca.
881  bool Inserted;
883  std::tie(MTPI, Inserted) =
884  MemTransferSliceMap.insert(std::make_pair(&II, AS.Slices.size()));
885  unsigned PrevIdx = MTPI->second;
886  if (!Inserted) {
887  Slice &PrevP = AS.Slices[PrevIdx];
888 
889  // Check if the begin offsets match and this is a non-volatile transfer.
890  // In that case, we can completely elide the transfer.
891  if (!II.isVolatile() && PrevP.beginOffset() == RawOffset) {
892  PrevP.kill();
893  return markAsDead(II);
894  }
895 
896  // Otherwise we have an offset transfer within the same alloca. We can't
897  // split those.
898  PrevP.makeUnsplittable();
899  }
900 
901  // Insert the use now that we've fixed up the splittable nature.
902  insertUse(II, Offset, Size, /*IsSplittable=*/Inserted && Length);
903 
904  // Check that we ended up with a valid index in the map.
905  assert(AS.Slices[PrevIdx].getUse()->getUser() == &II &&
906  "Map index doesn't point back to a slice with this user.");
907  }
908 
909  // Disable SRoA for any intrinsics except for lifetime invariants.
910  // FIXME: What about debug intrinsics? This matches old behavior, but
911  // doesn't make sense.
912  void visitIntrinsicInst(IntrinsicInst &II) {
913  if (!IsOffsetKnown)
914  return PI.setAborted(&II);
915 
916  if (II.isLifetimeStartOrEnd()) {
917  ConstantInt *Length = cast<ConstantInt>(II.getArgOperand(0));
918  uint64_t Size = std::min(AllocSize - Offset.getLimitedValue(),
919  Length->getLimitedValue());
920  insertUse(II, Offset, Size, true);
921  return;
922  }
923 
924  Base::visitIntrinsicInst(II);
925  }
926 
927  Instruction *hasUnsafePHIOrSelectUse(Instruction *Root, uint64_t &Size) {
928  // We consider any PHI or select that results in a direct load or store of
929  // the same offset to be a viable use for slicing purposes. These uses
930  // are considered unsplittable and the size is the maximum loaded or stored
931  // size.
934  Visited.insert(Root);
935  Uses.push_back(std::make_pair(cast<Instruction>(*U), Root));
936  const DataLayout &DL = Root->getModule()->getDataLayout();
937  // If there are no loads or stores, the access is dead. We mark that as
938  // a size zero access.
939  Size = 0;
940  do {
941  Instruction *I, *UsedI;
942  std::tie(UsedI, I) = Uses.pop_back_val();
943 
944  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
945  Size = std::max(Size, DL.getTypeStoreSize(LI->getType()));
946  continue;
947  }
948  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
949  Value *Op = SI->getOperand(0);
950  if (Op == UsedI)
951  return SI;
952  Size = std::max(Size, DL.getTypeStoreSize(Op->getType()));
953  continue;
954  }
955 
956  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
957  if (!GEP->hasAllZeroIndices())
958  return GEP;
959  } else if (!isa<BitCastInst>(I) && !isa<PHINode>(I) &&
960  !isa<SelectInst>(I)) {
961  return I;
962  }
963 
964  for (User *U : I->users())
965  if (Visited.insert(cast<Instruction>(U)).second)
966  Uses.push_back(std::make_pair(I, cast<Instruction>(U)));
967  } while (!Uses.empty());
968 
969  return nullptr;
970  }
971 
972  void visitPHINodeOrSelectInst(Instruction &I) {
973  assert(isa<PHINode>(I) || isa<SelectInst>(I));
974  if (I.use_empty())
975  return markAsDead(I);
976 
977  // TODO: We could use SimplifyInstruction here to fold PHINodes and
978  // SelectInsts. However, doing so requires to change the current
979  // dead-operand-tracking mechanism. For instance, suppose neither loading
980  // from %U nor %other traps. Then "load (select undef, %U, %other)" does not
981  // trap either. However, if we simply replace %U with undef using the
982  // current dead-operand-tracking mechanism, "load (select undef, undef,
983  // %other)" may trap because the select may return the first operand
984  // "undef".
985  if (Value *Result = foldPHINodeOrSelectInst(I)) {
986  if (Result == *U)
987  // If the result of the constant fold will be the pointer, recurse
988  // through the PHI/select as if we had RAUW'ed it.
989  enqueueUsers(I);
990  else
991  // Otherwise the operand to the PHI/select is dead, and we can replace
992  // it with undef.
993  AS.DeadOperands.push_back(U);
994 
995  return;
996  }
997 
998  if (!IsOffsetKnown)
999  return PI.setAborted(&I);
1000 
1001  // See if we already have computed info on this node.
1002  uint64_t &Size = PHIOrSelectSizes[&I];
1003  if (!Size) {
1004  // This is a new PHI/Select, check for an unsafe use of it.
1005  if (Instruction *UnsafeI = hasUnsafePHIOrSelectUse(&I, Size))
1006  return PI.setAborted(UnsafeI);
1007  }
1008 
1009  // For PHI and select operands outside the alloca, we can't nuke the entire
1010  // phi or select -- the other side might still be relevant, so we special
1011  // case them here and use a separate structure to track the operands
1012  // themselves which should be replaced with undef.
1013  // FIXME: This should instead be escaped in the event we're instrumenting
1014  // for address sanitization.
1015  if (Offset.uge(AllocSize)) {
1016  AS.DeadOperands.push_back(U);
1017  return;
1018  }
1019 
1020  insertUse(I, Offset, Size);
1021  }
1022 
1023  void visitPHINode(PHINode &PN) { visitPHINodeOrSelectInst(PN); }
1024 
1025  void visitSelectInst(SelectInst &SI) { visitPHINodeOrSelectInst(SI); }
1026 
1027  /// Disable SROA entirely if there are unhandled users of the alloca.
1028  void visitInstruction(Instruction &I) { PI.setAborted(&I); }
1029 };
1030 
1032  :
1033 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1034  AI(AI),
1035 #endif
1036  PointerEscapingInstr(nullptr) {
1037  SliceBuilder PB(DL, AI, *this);
1038  SliceBuilder::PtrInfo PtrI = PB.visitPtr(AI);
1039  if (PtrI.isEscaped() || PtrI.isAborted()) {
1040  // FIXME: We should sink the escape vs. abort info into the caller nicely,
1041  // possibly by just storing the PtrInfo in the AllocaSlices.
1042  PointerEscapingInstr = PtrI.getEscapingInst() ? PtrI.getEscapingInst()
1043  : PtrI.getAbortingInst();
1044  assert(PointerEscapingInstr && "Did not track a bad instruction");
1045  return;
1046  }
1047 
1048  Slices.erase(
1049  llvm::remove_if(Slices, [](const Slice &S) { return S.isDead(); }),
1050  Slices.end());
1051 
1052 #ifndef NDEBUG
1054  std::mt19937 MT(static_cast<unsigned>(
1055  std::chrono::system_clock::now().time_since_epoch().count()));
1056  std::shuffle(Slices.begin(), Slices.end(), MT);
1057  }
1058 #endif
1059 
1060  // Sort the uses. This arranges for the offsets to be in ascending order,
1061  // and the sizes to be in descending order.
1062  llvm::sort(Slices);
1063 }
1064 
1065 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1066 
1067 void AllocaSlices::print(raw_ostream &OS, const_iterator I,
1068  StringRef Indent) const {
1069  printSlice(OS, I, Indent);
1070  OS << "\n";
1071  printUse(OS, I, Indent);
1072 }
1073 
1074 void AllocaSlices::printSlice(raw_ostream &OS, const_iterator I,
1075  StringRef Indent) const {
1076  OS << Indent << "[" << I->beginOffset() << "," << I->endOffset() << ")"
1077  << " slice #" << (I - begin())
1078  << (I->isSplittable() ? " (splittable)" : "");
1079 }
1080 
1081 void AllocaSlices::printUse(raw_ostream &OS, const_iterator I,
1082  StringRef Indent) const {
1083  OS << Indent << " used by: " << *I->getUse()->getUser() << "\n";
1084 }
1085 
1086 void AllocaSlices::print(raw_ostream &OS) const {
1087  if (PointerEscapingInstr) {
1088  OS << "Can't analyze slices for alloca: " << AI << "\n"
1089  << " A pointer to this alloca escaped by:\n"
1090  << " " << *PointerEscapingInstr << "\n";
1091  return;
1092  }
1093 
1094  OS << "Slices of alloca: " << AI << "\n";
1095  for (const_iterator I = begin(), E = end(); I != E; ++I)
1096  print(OS, I);
1097 }
1098 
1099 LLVM_DUMP_METHOD void AllocaSlices::dump(const_iterator I) const {
1100  print(dbgs(), I);
1101 }
1102 LLVM_DUMP_METHOD void AllocaSlices::dump() const { print(dbgs()); }
1103 
1104 #endif // !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
1105 
1106 /// Walk the range of a partitioning looking for a common type to cover this
1107 /// sequence of slices.
1110  uint64_t EndOffset) {
1111  Type *Ty = nullptr;
1112  bool TyIsCommon = true;
1113  IntegerType *ITy = nullptr;
1114 
1115  // Note that we need to look at *every* alloca slice's Use to ensure we
1116  // always get consistent results regardless of the order of slices.
1117  for (AllocaSlices::const_iterator I = B; I != E; ++I) {
1118  Use *U = I->getUse();
1119  if (isa<IntrinsicInst>(*U->getUser()))
1120  continue;
1121  if (I->beginOffset() != B->beginOffset() || I->endOffset() != EndOffset)
1122  continue;
1123 
1124  Type *UserTy = nullptr;
1125  if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
1126  UserTy = LI->getType();
1127  } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) {
1128  UserTy = SI->getValueOperand()->getType();
1129  }
1130 
1131  if (IntegerType *UserITy = dyn_cast_or_null<IntegerType>(UserTy)) {
1132  // If the type is larger than the partition, skip it. We only encounter
1133  // this for split integer operations where we want to use the type of the
1134  // entity causing the split. Also skip if the type is not a byte width
1135  // multiple.
1136  if (UserITy->getBitWidth() % 8 != 0 ||
1137  UserITy->getBitWidth() / 8 > (EndOffset - B->beginOffset()))
1138  continue;
1139 
1140  // Track the largest bitwidth integer type used in this way in case there
1141  // is no common type.
1142  if (!ITy || ITy->getBitWidth() < UserITy->getBitWidth())
1143  ITy = UserITy;
1144  }
1145 
1146  // To avoid depending on the order of slices, Ty and TyIsCommon must not
1147  // depend on types skipped above.
1148  if (!UserTy || (Ty && Ty != UserTy))
1149  TyIsCommon = false; // Give up on anything but an iN type.
1150  else
1151  Ty = UserTy;
1152  }
1153 
1154  return TyIsCommon ? Ty : ITy;
1155 }
1156 
1157 /// PHI instructions that use an alloca and are subsequently loaded can be
1158 /// rewritten to load both input pointers in the pred blocks and then PHI the
1159 /// results, allowing the load of the alloca to be promoted.
1160 /// From this:
1161 /// %P2 = phi [i32* %Alloca, i32* %Other]
1162 /// %V = load i32* %P2
1163 /// to:
1164 /// %V1 = load i32* %Alloca -> will be mem2reg'd
1165 /// ...
1166 /// %V2 = load i32* %Other
1167 /// ...
1168 /// %V = phi [i32 %V1, i32 %V2]
1169 ///
1170 /// We can do this to a select if its only uses are loads and if the operands
1171 /// to the select can be loaded unconditionally.
1172 ///
1173 /// FIXME: This should be hoisted into a generic utility, likely in
1174 /// Transforms/Util/Local.h
1175 static bool isSafePHIToSpeculate(PHINode &PN) {
1176  // For now, we can only do this promotion if the load is in the same block
1177  // as the PHI, and if there are no stores between the phi and load.
1178  // TODO: Allow recursive phi users.
1179  // TODO: Allow stores.
1180  BasicBlock *BB = PN.getParent();
1181  unsigned MaxAlign = 0;
1182  bool HaveLoad = false;
1183  for (User *U : PN.users()) {
1184  LoadInst *LI = dyn_cast<LoadInst>(U);
1185  if (!LI || !LI->isSimple())
1186  return false;
1187 
1188  // For now we only allow loads in the same block as the PHI. This is
1189  // a common case that happens when instcombine merges two loads through
1190  // a PHI.
1191  if (LI->getParent() != BB)
1192  return false;
1193 
1194  // Ensure that there are no instructions between the PHI and the load that
1195  // could store.
1196  for (BasicBlock::iterator BBI(PN); &*BBI != LI; ++BBI)
1197  if (BBI->mayWriteToMemory())
1198  return false;
1199 
1200  MaxAlign = std::max(MaxAlign, LI->getAlignment());
1201  HaveLoad = true;
1202  }
1203 
1204  if (!HaveLoad)
1205  return false;
1206 
1207  const DataLayout &DL = PN.getModule()->getDataLayout();
1208 
1209  // We can only transform this if it is safe to push the loads into the
1210  // predecessor blocks. The only thing to watch out for is that we can't put
1211  // a possibly trapping load in the predecessor if it is a critical edge.
1212  for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) {
1213  Instruction *TI = PN.getIncomingBlock(Idx)->getTerminator();
1214  Value *InVal = PN.getIncomingValue(Idx);
1215 
1216  // If the value is produced by the terminator of the predecessor (an
1217  // invoke) or it has side-effects, there is no valid place to put a load
1218  // in the predecessor.
1219  if (TI == InVal || TI->mayHaveSideEffects())
1220  return false;
1221 
1222  // If the predecessor has a single successor, then the edge isn't
1223  // critical.
1224  if (TI->getNumSuccessors() == 1)
1225  continue;
1226 
1227  // If this pointer is always safe to load, or if we can prove that there
1228  // is already a load in the block, then we can move the load to the pred
1229  // block.
1230  if (isSafeToLoadUnconditionally(InVal, MaxAlign, DL, TI))
1231  continue;
1232 
1233  return false;
1234  }
1235 
1236  return true;
1237 }
1238 
1239 static void speculatePHINodeLoads(PHINode &PN) {
1240  LLVM_DEBUG(dbgs() << " original: " << PN << "\n");
1241 
1242  Type *LoadTy = cast<PointerType>(PN.getType())->getElementType();
1243  IRBuilderTy PHIBuilder(&PN);
1244  PHINode *NewPN = PHIBuilder.CreatePHI(LoadTy, PN.getNumIncomingValues(),
1245  PN.getName() + ".sroa.speculated");
1246 
1247  // Get the AA tags and alignment to use from one of the loads. It doesn't
1248  // matter which one we get and if any differ.
1249  LoadInst *SomeLoad = cast<LoadInst>(PN.user_back());
1250 
1251  AAMDNodes AATags;
1252  SomeLoad->getAAMetadata(AATags);
1253  unsigned Align = SomeLoad->getAlignment();
1254 
1255  // Rewrite all loads of the PN to use the new PHI.
1256  while (!PN.use_empty()) {
1257  LoadInst *LI = cast<LoadInst>(PN.user_back());
1258  LI->replaceAllUsesWith(NewPN);
1259  LI->eraseFromParent();
1260  }
1261 
1262  // Inject loads into all of the pred blocks.
1263  DenseMap<BasicBlock*, Value*> InjectedLoads;
1264  for (unsigned Idx = 0, Num = PN.getNumIncomingValues(); Idx != Num; ++Idx) {
1265  BasicBlock *Pred = PN.getIncomingBlock(Idx);
1266  Value *InVal = PN.getIncomingValue(Idx);
1267 
1268  // A PHI node is allowed to have multiple (duplicated) entries for the same
1269  // basic block, as long as the value is the same. So if we already injected
1270  // a load in the predecessor, then we should reuse the same load for all
1271  // duplicated entries.
1272  if (Value* V = InjectedLoads.lookup(Pred)) {
1273  NewPN->addIncoming(V, Pred);
1274  continue;
1275  }
1276 
1277  Instruction *TI = Pred->getTerminator();
1278  IRBuilderTy PredBuilder(TI);
1279 
1280  LoadInst *Load = PredBuilder.CreateLoad(
1281  InVal, (PN.getName() + ".sroa.speculate.load." + Pred->getName()));
1282  ++NumLoadsSpeculated;
1283  Load->setAlignment(Align);
1284  if (AATags)
1285  Load->setAAMetadata(AATags);
1286  NewPN->addIncoming(Load, Pred);
1287  InjectedLoads[Pred] = Load;
1288  }
1289 
1290  LLVM_DEBUG(dbgs() << " speculated to: " << *NewPN << "\n");
1291  PN.eraseFromParent();
1292 }
1293 
1294 /// Select instructions that use an alloca and are subsequently loaded can be
1295 /// rewritten to load both input pointers and then select between the result,
1296 /// allowing the load of the alloca to be promoted.
1297 /// From this:
1298 /// %P2 = select i1 %cond, i32* %Alloca, i32* %Other
1299 /// %V = load i32* %P2
1300 /// to:
1301 /// %V1 = load i32* %Alloca -> will be mem2reg'd
1302 /// %V2 = load i32* %Other
1303 /// %V = select i1 %cond, i32 %V1, i32 %V2
1304 ///
1305 /// We can do this to a select if its only uses are loads and if the operand
1306 /// to the select can be loaded unconditionally.
1308  Value *TValue = SI.getTrueValue();
1309  Value *FValue = SI.getFalseValue();
1310  const DataLayout &DL = SI.getModule()->getDataLayout();
1311 
1312  for (User *U : SI.users()) {
1313  LoadInst *LI = dyn_cast<LoadInst>(U);
1314  if (!LI || !LI->isSimple())
1315  return false;
1316 
1317  // Both operands to the select need to be dereferenceable, either
1318  // absolutely (e.g. allocas) or at this point because we can see other
1319  // accesses to it.
1320  if (!isSafeToLoadUnconditionally(TValue, LI->getAlignment(), DL, LI))
1321  return false;
1322  if (!isSafeToLoadUnconditionally(FValue, LI->getAlignment(), DL, LI))
1323  return false;
1324  }
1325 
1326  return true;
1327 }
1328 
1330  LLVM_DEBUG(dbgs() << " original: " << SI << "\n");
1331 
1332  IRBuilderTy IRB(&SI);
1333  Value *TV = SI.getTrueValue();
1334  Value *FV = SI.getFalseValue();
1335  // Replace the loads of the select with a select of two loads.
1336  while (!SI.use_empty()) {
1337  LoadInst *LI = cast<LoadInst>(SI.user_back());
1338  assert(LI->isSimple() && "We only speculate simple loads");
1339 
1340  IRB.SetInsertPoint(LI);
1341  LoadInst *TL =
1342  IRB.CreateLoad(TV, LI->getName() + ".sroa.speculate.load.true");
1343  LoadInst *FL =
1344  IRB.CreateLoad(FV, LI->getName() + ".sroa.speculate.load.false");
1345  NumLoadsSpeculated += 2;
1346 
1347  // Transfer alignment and AA info if present.
1348  TL->setAlignment(LI->getAlignment());
1349  FL->setAlignment(LI->getAlignment());
1350 
1351  AAMDNodes Tags;
1352  LI->getAAMetadata(Tags);
1353  if (Tags) {
1354  TL->setAAMetadata(Tags);
1355  FL->setAAMetadata(Tags);
1356  }
1357 
1358  Value *V = IRB.CreateSelect(SI.getCondition(), TL, FL,
1359  LI->getName() + ".sroa.speculated");
1360 
1361  LLVM_DEBUG(dbgs() << " speculated to: " << *V << "\n");
1362  LI->replaceAllUsesWith(V);
1363  LI->eraseFromParent();
1364  }
1365  SI.eraseFromParent();
1366 }
1367 
1368 /// Build a GEP out of a base pointer and indices.
1369 ///
1370 /// This will return the BasePtr if that is valid, or build a new GEP
1371 /// instruction using the IRBuilder if GEP-ing is needed.
1372 static Value *buildGEP(IRBuilderTy &IRB, Value *BasePtr,
1373  SmallVectorImpl<Value *> &Indices, Twine NamePrefix) {
1374  if (Indices.empty())
1375  return BasePtr;
1376 
1377  // A single zero index is a no-op, so check for this and avoid building a GEP
1378  // in that case.
1379  if (Indices.size() == 1 && cast<ConstantInt>(Indices.back())->isZero())
1380  return BasePtr;
1381 
1382  return IRB.CreateInBoundsGEP(nullptr, BasePtr, Indices,
1383  NamePrefix + "sroa_idx");
1384 }
1385 
1386 /// Get a natural GEP off of the BasePtr walking through Ty toward
1387 /// TargetTy without changing the offset of the pointer.
1388 ///
1389 /// This routine assumes we've already established a properly offset GEP with
1390 /// Indices, and arrived at the Ty type. The goal is to continue to GEP with
1391 /// zero-indices down through type layers until we find one the same as
1392 /// TargetTy. If we can't find one with the same type, we at least try to use
1393 /// one with the same size. If none of that works, we just produce the GEP as
1394 /// indicated by Indices to have the correct offset.
1395 static Value *getNaturalGEPWithType(IRBuilderTy &IRB, const DataLayout &DL,
1396  Value *BasePtr, Type *Ty, Type *TargetTy,
1397  SmallVectorImpl<Value *> &Indices,
1398  Twine NamePrefix) {
1399  if (Ty == TargetTy)
1400  return buildGEP(IRB, BasePtr, Indices, NamePrefix);
1401 
1402  // Offset size to use for the indices.
1403  unsigned OffsetSize = DL.getIndexTypeSizeInBits(BasePtr->getType());
1404 
1405  // See if we can descend into a struct and locate a field with the correct
1406  // type.
1407  unsigned NumLayers = 0;
1408  Type *ElementTy = Ty;
1409  do {
1410  if (ElementTy->isPointerTy())
1411  break;
1412 
1413  if (ArrayType *ArrayTy = dyn_cast<ArrayType>(ElementTy)) {
1414  ElementTy = ArrayTy->getElementType();
1415  Indices.push_back(IRB.getIntN(OffsetSize, 0));
1416  } else if (VectorType *VectorTy = dyn_cast<VectorType>(ElementTy)) {
1417  ElementTy = VectorTy->getElementType();
1418  Indices.push_back(IRB.getInt32(0));
1419  } else if (StructType *STy = dyn_cast<StructType>(ElementTy)) {
1420  if (STy->element_begin() == STy->element_end())
1421  break; // Nothing left to descend into.
1422  ElementTy = *STy->element_begin();
1423  Indices.push_back(IRB.getInt32(0));
1424  } else {
1425  break;
1426  }
1427  ++NumLayers;
1428  } while (ElementTy != TargetTy);
1429  if (ElementTy != TargetTy)
1430  Indices.erase(Indices.end() - NumLayers, Indices.end());
1431 
1432  return buildGEP(IRB, BasePtr, Indices, NamePrefix);
1433 }
1434 
1435 /// Recursively compute indices for a natural GEP.
1436 ///
1437 /// This is the recursive step for getNaturalGEPWithOffset that walks down the
1438 /// element types adding appropriate indices for the GEP.
1439 static Value *getNaturalGEPRecursively(IRBuilderTy &IRB, const DataLayout &DL,
1440  Value *Ptr, Type *Ty, APInt &Offset,
1441  Type *TargetTy,
1442  SmallVectorImpl<Value *> &Indices,
1443  Twine NamePrefix) {
1444  if (Offset == 0)
1445  return getNaturalGEPWithType(IRB, DL, Ptr, Ty, TargetTy, Indices,
1446  NamePrefix);
1447 
1448  // We can't recurse through pointer types.
1449  if (Ty->isPointerTy())
1450  return nullptr;
1451 
1452  // We try to analyze GEPs over vectors here, but note that these GEPs are
1453  // extremely poorly defined currently. The long-term goal is to remove GEPing
1454  // over a vector from the IR completely.
1455  if (VectorType *VecTy = dyn_cast<VectorType>(Ty)) {
1456  unsigned ElementSizeInBits = DL.getTypeSizeInBits(VecTy->getScalarType());
1457  if (ElementSizeInBits % 8 != 0) {
1458  // GEPs over non-multiple of 8 size vector elements are invalid.
1459  return nullptr;
1460  }
1461  APInt ElementSize(Offset.getBitWidth(), ElementSizeInBits / 8);
1462  APInt NumSkippedElements = Offset.sdiv(ElementSize);
1463  if (NumSkippedElements.ugt(VecTy->getNumElements()))
1464  return nullptr;
1465  Offset -= NumSkippedElements * ElementSize;
1466  Indices.push_back(IRB.getInt(NumSkippedElements));
1467  return getNaturalGEPRecursively(IRB, DL, Ptr, VecTy->getElementType(),
1468  Offset, TargetTy, Indices, NamePrefix);
1469  }
1470 
1471  if (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty)) {
1472  Type *ElementTy = ArrTy->getElementType();
1473  APInt ElementSize(Offset.getBitWidth(), DL.getTypeAllocSize(ElementTy));
1474  APInt NumSkippedElements = Offset.sdiv(ElementSize);
1475  if (NumSkippedElements.ugt(ArrTy->getNumElements()))
1476  return nullptr;
1477 
1478  Offset -= NumSkippedElements * ElementSize;
1479  Indices.push_back(IRB.getInt(NumSkippedElements));
1480  return getNaturalGEPRecursively(IRB, DL, Ptr, ElementTy, Offset, TargetTy,
1481  Indices, NamePrefix);
1482  }
1483 
1484  StructType *STy = dyn_cast<StructType>(Ty);
1485  if (!STy)
1486  return nullptr;
1487 
1488  const StructLayout *SL = DL.getStructLayout(STy);
1489  uint64_t StructOffset = Offset.getZExtValue();
1490  if (StructOffset >= SL->getSizeInBytes())
1491  return nullptr;
1492  unsigned Index = SL->getElementContainingOffset(StructOffset);
1493  Offset -= APInt(Offset.getBitWidth(), SL->getElementOffset(Index));
1494  Type *ElementTy = STy->getElementType(Index);
1495  if (Offset.uge(DL.getTypeAllocSize(ElementTy)))
1496  return nullptr; // The offset points into alignment padding.
1497 
1498  Indices.push_back(IRB.getInt32(Index));
1499  return getNaturalGEPRecursively(IRB, DL, Ptr, ElementTy, Offset, TargetTy,
1500  Indices, NamePrefix);
1501 }
1502 
1503 /// Get a natural GEP from a base pointer to a particular offset and
1504 /// resulting in a particular type.
1505 ///
1506 /// The goal is to produce a "natural" looking GEP that works with the existing
1507 /// composite types to arrive at the appropriate offset and element type for
1508 /// a pointer. TargetTy is the element type the returned GEP should point-to if
1509 /// possible. We recurse by decreasing Offset, adding the appropriate index to
1510 /// Indices, and setting Ty to the result subtype.
1511 ///
1512 /// If no natural GEP can be constructed, this function returns null.
1513 static Value *getNaturalGEPWithOffset(IRBuilderTy &IRB, const DataLayout &DL,
1514  Value *Ptr, APInt Offset, Type *TargetTy,
1515  SmallVectorImpl<Value *> &Indices,
1516  Twine NamePrefix) {
1517  PointerType *Ty = cast<PointerType>(Ptr->getType());
1518 
1519  // Don't consider any GEPs through an i8* as natural unless the TargetTy is
1520  // an i8.
1521  if (Ty == IRB.getInt8PtrTy(Ty->getAddressSpace()) && TargetTy->isIntegerTy(8))
1522  return nullptr;
1523 
1524  Type *ElementTy = Ty->getElementType();
1525  if (!ElementTy->isSized())
1526  return nullptr; // We can't GEP through an unsized element.
1527  APInt ElementSize(Offset.getBitWidth(), DL.getTypeAllocSize(ElementTy));
1528  if (ElementSize == 0)
1529  return nullptr; // Zero-length arrays can't help us build a natural GEP.
1530  APInt NumSkippedElements = Offset.sdiv(ElementSize);
1531 
1532  Offset -= NumSkippedElements * ElementSize;
1533  Indices.push_back(IRB.getInt(NumSkippedElements));
1534  return getNaturalGEPRecursively(IRB, DL, Ptr, ElementTy, Offset, TargetTy,
1535  Indices, NamePrefix);
1536 }
1537 
1538 /// Compute an adjusted pointer from Ptr by Offset bytes where the
1539 /// resulting pointer has PointerTy.
1540 ///
1541 /// This tries very hard to compute a "natural" GEP which arrives at the offset
1542 /// and produces the pointer type desired. Where it cannot, it will try to use
1543 /// the natural GEP to arrive at the offset and bitcast to the type. Where that
1544 /// fails, it will try to use an existing i8* and GEP to the byte offset and
1545 /// bitcast to the type.
1546 ///
1547 /// The strategy for finding the more natural GEPs is to peel off layers of the
1548 /// pointer, walking back through bit casts and GEPs, searching for a base
1549 /// pointer from which we can compute a natural GEP with the desired
1550 /// properties. The algorithm tries to fold as many constant indices into
1551 /// a single GEP as possible, thus making each GEP more independent of the
1552 /// surrounding code.
1553 static Value *getAdjustedPtr(IRBuilderTy &IRB, const DataLayout &DL, Value *Ptr,
1554  APInt Offset, Type *PointerTy, Twine NamePrefix) {
1555  // Even though we don't look through PHI nodes, we could be called on an
1556  // instruction in an unreachable block, which may be on a cycle.
1557  SmallPtrSet<Value *, 4> Visited;
1558  Visited.insert(Ptr);
1559  SmallVector<Value *, 4> Indices;
1560 
1561  // We may end up computing an offset pointer that has the wrong type. If we
1562  // never are able to compute one directly that has the correct type, we'll
1563  // fall back to it, so keep it and the base it was computed from around here.
1564  Value *OffsetPtr = nullptr;
1565  Value *OffsetBasePtr;
1566 
1567  // Remember any i8 pointer we come across to re-use if we need to do a raw
1568  // byte offset.
1569  Value *Int8Ptr = nullptr;
1570  APInt Int8PtrOffset(Offset.getBitWidth(), 0);
1571 
1572  Type *TargetTy = PointerTy->getPointerElementType();
1573 
1574  do {
1575  // First fold any existing GEPs into the offset.
1576  while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
1577  APInt GEPOffset(Offset.getBitWidth(), 0);
1578  if (!GEP->accumulateConstantOffset(DL, GEPOffset))
1579  break;
1580  Offset += GEPOffset;
1581  Ptr = GEP->getPointerOperand();
1582  if (!Visited.insert(Ptr).second)
1583  break;
1584  }
1585 
1586  // See if we can perform a natural GEP here.
1587  Indices.clear();
1588  if (Value *P = getNaturalGEPWithOffset(IRB, DL, Ptr, Offset, TargetTy,
1589  Indices, NamePrefix)) {
1590  // If we have a new natural pointer at the offset, clear out any old
1591  // offset pointer we computed. Unless it is the base pointer or
1592  // a non-instruction, we built a GEP we don't need. Zap it.
1593  if (OffsetPtr && OffsetPtr != OffsetBasePtr)
1594  if (Instruction *I = dyn_cast<Instruction>(OffsetPtr)) {
1595  assert(I->use_empty() && "Built a GEP with uses some how!");
1596  I->eraseFromParent();
1597  }
1598  OffsetPtr = P;
1599  OffsetBasePtr = Ptr;
1600  // If we also found a pointer of the right type, we're done.
1601  if (P->getType() == PointerTy)
1602  return P;
1603  }
1604 
1605  // Stash this pointer if we've found an i8*.
1606  if (Ptr->getType()->isIntegerTy(8)) {
1607  Int8Ptr = Ptr;
1608  Int8PtrOffset = Offset;
1609  }
1610 
1611  // Peel off a layer of the pointer and update the offset appropriately.
1612  if (Operator::getOpcode(Ptr) == Instruction::BitCast) {
1613  Ptr = cast<Operator>(Ptr)->getOperand(0);
1614  } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(Ptr)) {
1615  if (GA->isInterposable())
1616  break;
1617  Ptr = GA->getAliasee();
1618  } else {
1619  break;
1620  }
1621  assert(Ptr->getType()->isPointerTy() && "Unexpected operand type!");
1622  } while (Visited.insert(Ptr).second);
1623 
1624  if (!OffsetPtr) {
1625  if (!Int8Ptr) {
1626  Int8Ptr = IRB.CreateBitCast(
1627  Ptr, IRB.getInt8PtrTy(PointerTy->getPointerAddressSpace()),
1628  NamePrefix + "sroa_raw_cast");
1629  Int8PtrOffset = Offset;
1630  }
1631 
1632  OffsetPtr = Int8PtrOffset == 0
1633  ? Int8Ptr
1634  : IRB.CreateInBoundsGEP(IRB.getInt8Ty(), Int8Ptr,
1635  IRB.getInt(Int8PtrOffset),
1636  NamePrefix + "sroa_raw_idx");
1637  }
1638  Ptr = OffsetPtr;
1639 
1640  // On the off chance we were targeting i8*, guard the bitcast here.
1641  if (Ptr->getType() != PointerTy)
1642  Ptr = IRB.CreateBitCast(Ptr, PointerTy, NamePrefix + "sroa_cast");
1643 
1644  return Ptr;
1645 }
1646 
1647 /// Compute the adjusted alignment for a load or store from an offset.
1648 static unsigned getAdjustedAlignment(Instruction *I, uint64_t Offset,
1649  const DataLayout &DL) {
1650  unsigned Alignment;
1651  Type *Ty;
1652  if (auto *LI = dyn_cast<LoadInst>(I)) {
1653  Alignment = LI->getAlignment();
1654  Ty = LI->getType();
1655  } else if (auto *SI = dyn_cast<StoreInst>(I)) {
1656  Alignment = SI->getAlignment();
1657  Ty = SI->getValueOperand()->getType();
1658  } else {
1659  llvm_unreachable("Only loads and stores are allowed!");
1660  }
1661 
1662  if (!Alignment)
1663  Alignment = DL.getABITypeAlignment(Ty);
1664 
1665  return MinAlign(Alignment, Offset);
1666 }
1667 
1668 /// Test whether we can convert a value from the old to the new type.
1669 ///
1670 /// This predicate should be used to guard calls to convertValue in order to
1671 /// ensure that we only try to convert viable values. The strategy is that we
1672 /// will peel off single element struct and array wrappings to get to an
1673 /// underlying value, and convert that value.
1674 static bool canConvertValue(const DataLayout &DL, Type *OldTy, Type *NewTy) {
1675  if (OldTy == NewTy)
1676  return true;
1677 
1678  // For integer types, we can't handle any bit-width differences. This would
1679  // break both vector conversions with extension and introduce endianness
1680  // issues when in conjunction with loads and stores.
1681  if (isa<IntegerType>(OldTy) && isa<IntegerType>(NewTy)) {
1682  assert(cast<IntegerType>(OldTy)->getBitWidth() !=
1683  cast<IntegerType>(NewTy)->getBitWidth() &&
1684  "We can't have the same bitwidth for different int types");
1685  return false;
1686  }
1687 
1688  if (DL.getTypeSizeInBits(NewTy) != DL.getTypeSizeInBits(OldTy))
1689  return false;
1690  if (!NewTy->isSingleValueType() || !OldTy->isSingleValueType())
1691  return false;
1692 
1693  // We can convert pointers to integers and vice-versa. Same for vectors
1694  // of pointers and integers.
1695  OldTy = OldTy->getScalarType();
1696  NewTy = NewTy->getScalarType();
1697  if (NewTy->isPointerTy() || OldTy->isPointerTy()) {
1698  if (NewTy->isPointerTy() && OldTy->isPointerTy()) {
1699  return cast<PointerType>(NewTy)->getPointerAddressSpace() ==
1700  cast<PointerType>(OldTy)->getPointerAddressSpace();
1701  }
1702 
1703  // We can convert integers to integral pointers, but not to non-integral
1704  // pointers.
1705  if (OldTy->isIntegerTy())
1706  return !DL.isNonIntegralPointerType(NewTy);
1707 
1708  // We can convert integral pointers to integers, but non-integral pointers
1709  // need to remain pointers.
1710  if (!DL.isNonIntegralPointerType(OldTy))
1711  return NewTy->isIntegerTy();
1712 
1713  return false;
1714  }
1715 
1716  return true;
1717 }
1718 
1719 /// Generic routine to convert an SSA value to a value of a different
1720 /// type.
1721 ///
1722 /// This will try various different casting techniques, such as bitcasts,
1723 /// inttoptr, and ptrtoint casts. Use the \c canConvertValue predicate to test
1724 /// two types for viability with this routine.
1725 static Value *convertValue(const DataLayout &DL, IRBuilderTy &IRB, Value *V,
1726  Type *NewTy) {
1727  Type *OldTy = V->getType();
1728  assert(canConvertValue(DL, OldTy, NewTy) && "Value not convertable to type");
1729 
1730  if (OldTy == NewTy)
1731  return V;
1732 
1733  assert(!(isa<IntegerType>(OldTy) && isa<IntegerType>(NewTy)) &&
1734  "Integer types must be the exact same to convert.");
1735 
1736  // See if we need inttoptr for this type pair. A cast involving both scalars
1737  // and vectors requires and additional bitcast.
1738  if (OldTy->isIntOrIntVectorTy() && NewTy->isPtrOrPtrVectorTy()) {
1739  // Expand <2 x i32> to i8* --> <2 x i32> to i64 to i8*
1740  if (OldTy->isVectorTy() && !NewTy->isVectorTy())
1741  return IRB.CreateIntToPtr(IRB.CreateBitCast(V, DL.getIntPtrType(NewTy)),
1742  NewTy);
1743 
1744  // Expand i128 to <2 x i8*> --> i128 to <2 x i64> to <2 x i8*>
1745  if (!OldTy->isVectorTy() && NewTy->isVectorTy())
1746  return IRB.CreateIntToPtr(IRB.CreateBitCast(V, DL.getIntPtrType(NewTy)),
1747  NewTy);
1748 
1749  return IRB.CreateIntToPtr(V, NewTy);
1750  }
1751 
1752  // See if we need ptrtoint for this type pair. A cast involving both scalars
1753  // and vectors requires and additional bitcast.
1754  if (OldTy->isPtrOrPtrVectorTy() && NewTy->isIntOrIntVectorTy()) {
1755  // Expand <2 x i8*> to i128 --> <2 x i8*> to <2 x i64> to i128
1756  if (OldTy->isVectorTy() && !NewTy->isVectorTy())
1757  return IRB.CreateBitCast(IRB.CreatePtrToInt(V, DL.getIntPtrType(OldTy)),
1758  NewTy);
1759 
1760  // Expand i8* to <2 x i32> --> i8* to i64 to <2 x i32>
1761  if (!OldTy->isVectorTy() && NewTy->isVectorTy())
1762  return IRB.CreateBitCast(IRB.CreatePtrToInt(V, DL.getIntPtrType(OldTy)),
1763  NewTy);
1764 
1765  return IRB.CreatePtrToInt(V, NewTy);
1766  }
1767 
1768  return IRB.CreateBitCast(V, NewTy);
1769 }
1770 
1771 /// Test whether the given slice use can be promoted to a vector.
1772 ///
1773 /// This function is called to test each entry in a partition which is slated
1774 /// for a single slice.
1775 static bool isVectorPromotionViableForSlice(Partition &P, const Slice &S,
1776  VectorType *Ty,
1777  uint64_t ElementSize,
1778  const DataLayout &DL) {
1779  // First validate the slice offsets.
1780  uint64_t BeginOffset =
1781  std::max(S.beginOffset(), P.beginOffset()) - P.beginOffset();
1782  uint64_t BeginIndex = BeginOffset / ElementSize;
1783  if (BeginIndex * ElementSize != BeginOffset ||
1784  BeginIndex >= Ty->getNumElements())
1785  return false;
1786  uint64_t EndOffset =
1787  std::min(S.endOffset(), P.endOffset()) - P.beginOffset();
1788  uint64_t EndIndex = EndOffset / ElementSize;
1789  if (EndIndex * ElementSize != EndOffset || EndIndex > Ty->getNumElements())
1790  return false;
1791 
1792  assert(EndIndex > BeginIndex && "Empty vector!");
1793  uint64_t NumElements = EndIndex - BeginIndex;
1794  Type *SliceTy = (NumElements == 1)
1795  ? Ty->getElementType()
1796  : VectorType::get(Ty->getElementType(), NumElements);
1797 
1798  Type *SplitIntTy =
1799  Type::getIntNTy(Ty->getContext(), NumElements * ElementSize * 8);
1800 
1801  Use *U = S.getUse();
1802 
1803  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) {
1804  if (MI->isVolatile())
1805  return false;
1806  if (!S.isSplittable())
1807  return false; // Skip any unsplittable intrinsics.
1808  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
1809  if (!II->isLifetimeStartOrEnd())
1810  return false;
1811  } else if (U->get()->getType()->getPointerElementType()->isStructTy()) {
1812  // Disable vector promotion when there are loads or stores of an FCA.
1813  return false;
1814  } else if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
1815  if (LI->isVolatile())
1816  return false;
1817  Type *LTy = LI->getType();
1818  if (P.beginOffset() > S.beginOffset() || P.endOffset() < S.endOffset()) {
1819  assert(LTy->isIntegerTy());
1820  LTy = SplitIntTy;
1821  }
1822  if (!canConvertValue(DL, SliceTy, LTy))
1823  return false;
1824  } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) {
1825  if (SI->isVolatile())
1826  return false;
1827  Type *STy = SI->getValueOperand()->getType();
1828  if (P.beginOffset() > S.beginOffset() || P.endOffset() < S.endOffset()) {
1829  assert(STy->isIntegerTy());
1830  STy = SplitIntTy;
1831  }
1832  if (!canConvertValue(DL, STy, SliceTy))
1833  return false;
1834  } else {
1835  return false;
1836  }
1837 
1838  return true;
1839 }
1840 
1841 /// Test whether the given alloca partitioning and range of slices can be
1842 /// promoted to a vector.
1843 ///
1844 /// This is a quick test to check whether we can rewrite a particular alloca
1845 /// partition (and its newly formed alloca) into a vector alloca with only
1846 /// whole-vector loads and stores such that it could be promoted to a vector
1847 /// SSA value. We only can ensure this for a limited set of operations, and we
1848 /// don't want to do the rewrites unless we are confident that the result will
1849 /// be promotable, so we have an early test here.
1851  // Collect the candidate types for vector-based promotion. Also track whether
1852  // we have different element types.
1853  SmallVector<VectorType *, 4> CandidateTys;
1854  Type *CommonEltTy = nullptr;
1855  bool HaveCommonEltTy = true;
1856  auto CheckCandidateType = [&](Type *Ty) {
1857  if (auto *VTy = dyn_cast<VectorType>(Ty)) {
1858  CandidateTys.push_back(VTy);
1859  if (!CommonEltTy)
1860  CommonEltTy = VTy->getElementType();
1861  else if (CommonEltTy != VTy->getElementType())
1862  HaveCommonEltTy = false;
1863  }
1864  };
1865  // Consider any loads or stores that are the exact size of the slice.
1866  for (const Slice &S : P)
1867  if (S.beginOffset() == P.beginOffset() &&
1868  S.endOffset() == P.endOffset()) {
1869  if (auto *LI = dyn_cast<LoadInst>(S.getUse()->getUser()))
1870  CheckCandidateType(LI->getType());
1871  else if (auto *SI = dyn_cast<StoreInst>(S.getUse()->getUser()))
1872  CheckCandidateType(SI->getValueOperand()->getType());
1873  }
1874 
1875  // If we didn't find a vector type, nothing to do here.
1876  if (CandidateTys.empty())
1877  return nullptr;
1878 
1879  // Remove non-integer vector types if we had multiple common element types.
1880  // FIXME: It'd be nice to replace them with integer vector types, but we can't
1881  // do that until all the backends are known to produce good code for all
1882  // integer vector types.
1883  if (!HaveCommonEltTy) {
1884  CandidateTys.erase(
1885  llvm::remove_if(CandidateTys,
1886  [](VectorType *VTy) {
1887  return !VTy->getElementType()->isIntegerTy();
1888  }),
1889  CandidateTys.end());
1890 
1891  // If there were no integer vector types, give up.
1892  if (CandidateTys.empty())
1893  return nullptr;
1894 
1895  // Rank the remaining candidate vector types. This is easy because we know
1896  // they're all integer vectors. We sort by ascending number of elements.
1897  auto RankVectorTypes = [&DL](VectorType *RHSTy, VectorType *LHSTy) {
1898  (void)DL;
1899  assert(DL.getTypeSizeInBits(RHSTy) == DL.getTypeSizeInBits(LHSTy) &&
1900  "Cannot have vector types of different sizes!");
1901  assert(RHSTy->getElementType()->isIntegerTy() &&
1902  "All non-integer types eliminated!");
1903  assert(LHSTy->getElementType()->isIntegerTy() &&
1904  "All non-integer types eliminated!");
1905  return RHSTy->getNumElements() < LHSTy->getNumElements();
1906  };
1907  llvm::sort(CandidateTys, RankVectorTypes);
1908  CandidateTys.erase(
1909  std::unique(CandidateTys.begin(), CandidateTys.end(), RankVectorTypes),
1910  CandidateTys.end());
1911  } else {
1912 // The only way to have the same element type in every vector type is to
1913 // have the same vector type. Check that and remove all but one.
1914 #ifndef NDEBUG
1915  for (VectorType *VTy : CandidateTys) {
1916  assert(VTy->getElementType() == CommonEltTy &&
1917  "Unaccounted for element type!");
1918  assert(VTy == CandidateTys[0] &&
1919  "Different vector types with the same element type!");
1920  }
1921 #endif
1922  CandidateTys.resize(1);
1923  }
1924 
1925  // Try each vector type, and return the one which works.
1926  auto CheckVectorTypeForPromotion = [&](VectorType *VTy) {
1927  uint64_t ElementSize = DL.getTypeSizeInBits(VTy->getElementType());
1928 
1929  // While the definition of LLVM vectors is bitpacked, we don't support sizes
1930  // that aren't byte sized.
1931  if (ElementSize % 8)
1932  return false;
1933  assert((DL.getTypeSizeInBits(VTy) % 8) == 0 &&
1934  "vector size not a multiple of element size?");
1935  ElementSize /= 8;
1936 
1937  for (const Slice &S : P)
1938  if (!isVectorPromotionViableForSlice(P, S, VTy, ElementSize, DL))
1939  return false;
1940 
1941  for (const Slice *S : P.splitSliceTails())
1942  if (!isVectorPromotionViableForSlice(P, *S, VTy, ElementSize, DL))
1943  return false;
1944 
1945  return true;
1946  };
1947  for (VectorType *VTy : CandidateTys)
1948  if (CheckVectorTypeForPromotion(VTy))
1949  return VTy;
1950 
1951  return nullptr;
1952 }
1953 
1954 /// Test whether a slice of an alloca is valid for integer widening.
1955 ///
1956 /// This implements the necessary checking for the \c isIntegerWideningViable
1957 /// test below on a single slice of the alloca.
1958 static bool isIntegerWideningViableForSlice(const Slice &S,
1959  uint64_t AllocBeginOffset,
1960  Type *AllocaTy,
1961  const DataLayout &DL,
1962  bool &WholeAllocaOp) {
1963  uint64_t Size = DL.getTypeStoreSize(AllocaTy);
1964 
1965  uint64_t RelBegin = S.beginOffset() - AllocBeginOffset;
1966  uint64_t RelEnd = S.endOffset() - AllocBeginOffset;
1967 
1968  // We can't reasonably handle cases where the load or store extends past
1969  // the end of the alloca's type and into its padding.
1970  if (RelEnd > Size)
1971  return false;
1972 
1973  Use *U = S.getUse();
1974 
1975  if (LoadInst *LI = dyn_cast<LoadInst>(U->getUser())) {
1976  if (LI->isVolatile())
1977  return false;
1978  // We can't handle loads that extend past the allocated memory.
1979  if (DL.getTypeStoreSize(LI->getType()) > Size)
1980  return false;
1981  // So far, AllocaSliceRewriter does not support widening split slice tails
1982  // in rewriteIntegerLoad.
1983  if (S.beginOffset() < AllocBeginOffset)
1984  return false;
1985  // Note that we don't count vector loads or stores as whole-alloca
1986  // operations which enable integer widening because we would prefer to use
1987  // vector widening instead.
1988  if (!isa<VectorType>(LI->getType()) && RelBegin == 0 && RelEnd == Size)
1989  WholeAllocaOp = true;
1990  if (IntegerType *ITy = dyn_cast<IntegerType>(LI->getType())) {
1991  if (ITy->getBitWidth() < DL.getTypeStoreSizeInBits(ITy))
1992  return false;
1993  } else if (RelBegin != 0 || RelEnd != Size ||
1994  !canConvertValue(DL, AllocaTy, LI->getType())) {
1995  // Non-integer loads need to be convertible from the alloca type so that
1996  // they are promotable.
1997  return false;
1998  }
1999  } else if (StoreInst *SI = dyn_cast<StoreInst>(U->getUser())) {
2000  Type *ValueTy = SI->getValueOperand()->getType();
2001  if (SI->isVolatile())
2002  return false;
2003  // We can't handle stores that extend past the allocated memory.
2004  if (DL.getTypeStoreSize(ValueTy) > Size)
2005  return false;
2006  // So far, AllocaSliceRewriter does not support widening split slice tails
2007  // in rewriteIntegerStore.
2008  if (S.beginOffset() < AllocBeginOffset)
2009  return false;
2010  // Note that we don't count vector loads or stores as whole-alloca
2011  // operations which enable integer widening because we would prefer to use
2012  // vector widening instead.
2013  if (!isa<VectorType>(ValueTy) && RelBegin == 0 && RelEnd == Size)
2014  WholeAllocaOp = true;
2015  if (IntegerType *ITy = dyn_cast<IntegerType>(ValueTy)) {
2016  if (ITy->getBitWidth() < DL.getTypeStoreSizeInBits(ITy))
2017  return false;
2018  } else if (RelBegin != 0 || RelEnd != Size ||
2019  !canConvertValue(DL, ValueTy, AllocaTy)) {
2020  // Non-integer stores need to be convertible to the alloca type so that
2021  // they are promotable.
2022  return false;
2023  }
2024  } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U->getUser())) {
2025  if (MI->isVolatile() || !isa<Constant>(MI->getLength()))
2026  return false;
2027  if (!S.isSplittable())
2028  return false; // Skip any unsplittable intrinsics.
2029  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
2030  if (!II->isLifetimeStartOrEnd())
2031  return false;
2032  } else {
2033  return false;
2034  }
2035 
2036  return true;
2037 }
2038 
2039 /// Test whether the given alloca partition's integer operations can be
2040 /// widened to promotable ones.
2041 ///
2042 /// This is a quick test to check whether we can rewrite the integer loads and
2043 /// stores to a particular alloca into wider loads and stores and be able to
2044 /// promote the resulting alloca.
2045 static bool isIntegerWideningViable(Partition &P, Type *AllocaTy,
2046  const DataLayout &DL) {
2047  uint64_t SizeInBits = DL.getTypeSizeInBits(AllocaTy);
2048  // Don't create integer types larger than the maximum bitwidth.
2049  if (SizeInBits > IntegerType::MAX_INT_BITS)
2050  return false;
2051 
2052  // Don't try to handle allocas with bit-padding.
2053  if (SizeInBits != DL.getTypeStoreSizeInBits(AllocaTy))
2054  return false;
2055 
2056  // We need to ensure that an integer type with the appropriate bitwidth can
2057  // be converted to the alloca type, whatever that is. We don't want to force
2058  // the alloca itself to have an integer type if there is a more suitable one.
2059  Type *IntTy = Type::getIntNTy(AllocaTy->getContext(), SizeInBits);
2060  if (!canConvertValue(DL, AllocaTy, IntTy) ||
2061  !canConvertValue(DL, IntTy, AllocaTy))
2062  return false;
2063 
2064  // While examining uses, we ensure that the alloca has a covering load or
2065  // store. We don't want to widen the integer operations only to fail to
2066  // promote due to some other unsplittable entry (which we may make splittable
2067  // later). However, if there are only splittable uses, go ahead and assume
2068  // that we cover the alloca.
2069  // FIXME: We shouldn't consider split slices that happen to start in the
2070  // partition here...
2071  bool WholeAllocaOp =
2072  P.begin() != P.end() ? false : DL.isLegalInteger(SizeInBits);
2073 
2074  for (const Slice &S : P)
2075  if (!isIntegerWideningViableForSlice(S, P.beginOffset(), AllocaTy, DL,
2076  WholeAllocaOp))
2077  return false;
2078 
2079  for (const Slice *S : P.splitSliceTails())
2080  if (!isIntegerWideningViableForSlice(*S, P.beginOffset(), AllocaTy, DL,
2081  WholeAllocaOp))
2082  return false;
2083 
2084  return WholeAllocaOp;
2085 }
2086 
2087 static Value *extractInteger(const DataLayout &DL, IRBuilderTy &IRB, Value *V,
2088  IntegerType *Ty, uint64_t Offset,
2089  const Twine &Name) {
2090  LLVM_DEBUG(dbgs() << " start: " << *V << "\n");
2091  IntegerType *IntTy = cast<IntegerType>(V->getType());
2092  assert(DL.getTypeStoreSize(Ty) + Offset <= DL.getTypeStoreSize(IntTy) &&
2093  "Element extends past full value");
2094  uint64_t ShAmt = 8 * Offset;
2095  if (DL.isBigEndian())
2096  ShAmt = 8 * (DL.getTypeStoreSize(IntTy) - DL.getTypeStoreSize(Ty) - Offset);
2097  if (ShAmt) {
2098  V = IRB.CreateLShr(V, ShAmt, Name + ".shift");
2099  LLVM_DEBUG(dbgs() << " shifted: " << *V << "\n");
2100  }
2101  assert(Ty->getBitWidth() <= IntTy->getBitWidth() &&
2102  "Cannot extract to a larger integer!");
2103  if (Ty != IntTy) {
2104  V = IRB.CreateTrunc(V, Ty, Name + ".trunc");
2105  LLVM_DEBUG(dbgs() << " trunced: " << *V << "\n");
2106  }
2107  return V;
2108 }
2109 
2110 static Value *insertInteger(const DataLayout &DL, IRBuilderTy &IRB, Value *Old,
2111  Value *V, uint64_t Offset, const Twine &Name) {
2112  IntegerType *IntTy = cast<IntegerType>(Old->getType());
2113  IntegerType *Ty = cast<IntegerType>(V->getType());
2114  assert(Ty->getBitWidth() <= IntTy->getBitWidth() &&
2115  "Cannot insert a larger integer!");
2116  LLVM_DEBUG(dbgs() << " start: " << *V << "\n");
2117  if (Ty != IntTy) {
2118  V = IRB.CreateZExt(V, IntTy, Name + ".ext");
2119  LLVM_DEBUG(dbgs() << " extended: " << *V << "\n");
2120  }
2121  assert(DL.getTypeStoreSize(Ty) + Offset <= DL.getTypeStoreSize(IntTy) &&
2122  "Element store outside of alloca store");
2123  uint64_t ShAmt = 8 * Offset;
2124  if (DL.isBigEndian())
2125  ShAmt = 8 * (DL.getTypeStoreSize(IntTy) - DL.getTypeStoreSize(Ty) - Offset);
2126  if (ShAmt) {
2127  V = IRB.CreateShl(V, ShAmt, Name + ".shift");
2128  LLVM_DEBUG(dbgs() << " shifted: " << *V << "\n");
2129  }
2130 
2131  if (ShAmt || Ty->getBitWidth() < IntTy->getBitWidth()) {
2132  APInt Mask = ~Ty->getMask().zext(IntTy->getBitWidth()).shl(ShAmt);
2133  Old = IRB.CreateAnd(Old, Mask, Name + ".mask");
2134  LLVM_DEBUG(dbgs() << " masked: " << *Old << "\n");
2135  V = IRB.CreateOr(Old, V, Name + ".insert");
2136  LLVM_DEBUG(dbgs() << " inserted: " << *V << "\n");
2137  }
2138  return V;
2139 }
2140 
2141 static Value *extractVector(IRBuilderTy &IRB, Value *V, unsigned BeginIndex,
2142  unsigned EndIndex, const Twine &Name) {
2143  VectorType *VecTy = cast<VectorType>(V->getType());
2144  unsigned NumElements = EndIndex - BeginIndex;
2145  assert(NumElements <= VecTy->getNumElements() && "Too many elements!");
2146 
2147  if (NumElements == VecTy->getNumElements())
2148  return V;
2149 
2150  if (NumElements == 1) {
2151  V = IRB.CreateExtractElement(V, IRB.getInt32(BeginIndex),
2152  Name + ".extract");
2153  LLVM_DEBUG(dbgs() << " extract: " << *V << "\n");
2154  return V;
2155  }
2156 
2158  Mask.reserve(NumElements);
2159  for (unsigned i = BeginIndex; i != EndIndex; ++i)
2160  Mask.push_back(IRB.getInt32(i));
2161  V = IRB.CreateShuffleVector(V, UndefValue::get(V->getType()),
2162  ConstantVector::get(Mask), Name + ".extract");
2163  LLVM_DEBUG(dbgs() << " shuffle: " << *V << "\n");
2164  return V;
2165 }
2166 
2167 static Value *insertVector(IRBuilderTy &IRB, Value *Old, Value *V,
2168  unsigned BeginIndex, const Twine &Name) {
2169  VectorType *VecTy = cast<VectorType>(Old->getType());
2170  assert(VecTy && "Can only insert a vector into a vector");
2171 
2172  VectorType *Ty = dyn_cast<VectorType>(V->getType());
2173  if (!Ty) {
2174  // Single element to insert.
2175  V = IRB.CreateInsertElement(Old, V, IRB.getInt32(BeginIndex),
2176  Name + ".insert");
2177  LLVM_DEBUG(dbgs() << " insert: " << *V << "\n");
2178  return V;
2179  }
2180 
2181  assert(Ty->getNumElements() <= VecTy->getNumElements() &&
2182  "Too many elements!");
2183  if (Ty->getNumElements() == VecTy->getNumElements()) {
2184  assert(V->getType() == VecTy && "Vector type mismatch");
2185  return V;
2186  }
2187  unsigned EndIndex = BeginIndex + Ty->getNumElements();
2188 
2189  // When inserting a smaller vector into the larger to store, we first
2190  // use a shuffle vector to widen it with undef elements, and then
2191  // a second shuffle vector to select between the loaded vector and the
2192  // incoming vector.
2194  Mask.reserve(VecTy->getNumElements());
2195  for (unsigned i = 0; i != VecTy->getNumElements(); ++i)
2196  if (i >= BeginIndex && i < EndIndex)
2197  Mask.push_back(IRB.getInt32(i - BeginIndex));
2198  else
2199  Mask.push_back(UndefValue::get(IRB.getInt32Ty()));
2200  V = IRB.CreateShuffleVector(V, UndefValue::get(V->getType()),
2201  ConstantVector::get(Mask), Name + ".expand");
2202  LLVM_DEBUG(dbgs() << " shuffle: " << *V << "\n");
2203 
2204  Mask.clear();
2205  for (unsigned i = 0; i != VecTy->getNumElements(); ++i)
2206  Mask.push_back(IRB.getInt1(i >= BeginIndex && i < EndIndex));
2207 
2208  V = IRB.CreateSelect(ConstantVector::get(Mask), V, Old, Name + "blend");
2209 
2210  LLVM_DEBUG(dbgs() << " blend: " << *V << "\n");
2211  return V;
2212 }
2213 
2214 /// Visitor to rewrite instructions using p particular slice of an alloca
2215 /// to use a new alloca.
2216 ///
2217 /// Also implements the rewriting to vector-based accesses when the partition
2218 /// passes the isVectorPromotionViable predicate. Most of the rewriting logic
2219 /// lives here.
2221  : public InstVisitor<AllocaSliceRewriter, bool> {
2222  // Befriend the base class so it can delegate to private visit methods.
2224 
2226 
2227  const DataLayout &DL;
2228  AllocaSlices &AS;
2229  SROA &Pass;
2230  AllocaInst &OldAI, &NewAI;
2231  const uint64_t NewAllocaBeginOffset, NewAllocaEndOffset;
2232  Type *NewAllocaTy;
2233 
2234  // This is a convenience and flag variable that will be null unless the new
2235  // alloca's integer operations should be widened to this integer type due to
2236  // passing isIntegerWideningViable above. If it is non-null, the desired
2237  // integer type will be stored here for easy access during rewriting.
2238  IntegerType *IntTy;
2239 
2240  // If we are rewriting an alloca partition which can be written as pure
2241  // vector operations, we stash extra information here. When VecTy is
2242  // non-null, we have some strict guarantees about the rewritten alloca:
2243  // - The new alloca is exactly the size of the vector type here.
2244  // - The accesses all either map to the entire vector or to a single
2245  // element.
2246  // - The set of accessing instructions is only one of those handled above
2247  // in isVectorPromotionViable. Generally these are the same access kinds
2248  // which are promotable via mem2reg.
2249  VectorType *VecTy;
2250  Type *ElementTy;
2251  uint64_t ElementSize;
2252 
2253  // The original offset of the slice currently being rewritten relative to
2254  // the original alloca.
2255  uint64_t BeginOffset = 0;
2256  uint64_t EndOffset = 0;
2257 
2258  // The new offsets of the slice currently being rewritten relative to the
2259  // original alloca.
2260  uint64_t NewBeginOffset, NewEndOffset;
2261 
2262  uint64_t SliceSize;
2263  bool IsSplittable = false;
2264  bool IsSplit = false;
2265  Use *OldUse = nullptr;
2266  Instruction *OldPtr = nullptr;
2267 
2268  // Track post-rewrite users which are PHI nodes and Selects.
2269  SmallSetVector<PHINode *, 8> &PHIUsers;
2270  SmallSetVector<SelectInst *, 8> &SelectUsers;
2271 
2272  // Utility IR builder, whose name prefix is setup for each visited use, and
2273  // the insertion point is set to point to the user.
2274  IRBuilderTy IRB;
2275 
2276 public:
2278  AllocaInst &OldAI, AllocaInst &NewAI,
2279  uint64_t NewAllocaBeginOffset,
2280  uint64_t NewAllocaEndOffset, bool IsIntegerPromotable,
2281  VectorType *PromotableVecTy,
2282  SmallSetVector<PHINode *, 8> &PHIUsers,
2283  SmallSetVector<SelectInst *, 8> &SelectUsers)
2284  : DL(DL), AS(AS), Pass(Pass), OldAI(OldAI), NewAI(NewAI),
2285  NewAllocaBeginOffset(NewAllocaBeginOffset),
2286  NewAllocaEndOffset(NewAllocaEndOffset),
2287  NewAllocaTy(NewAI.getAllocatedType()),
2288  IntTy(IsIntegerPromotable
2289  ? Type::getIntNTy(
2290  NewAI.getContext(),
2291  DL.getTypeSizeInBits(NewAI.getAllocatedType()))
2292  : nullptr),
2293  VecTy(PromotableVecTy),
2294  ElementTy(VecTy ? VecTy->getElementType() : nullptr),
2295  ElementSize(VecTy ? DL.getTypeSizeInBits(ElementTy) / 8 : 0),
2296  PHIUsers(PHIUsers), SelectUsers(SelectUsers),
2297  IRB(NewAI.getContext(), ConstantFolder()) {
2298  if (VecTy) {
2299  assert((DL.getTypeSizeInBits(ElementTy) % 8) == 0 &&
2300  "Only multiple-of-8 sized vector elements are viable");
2301  ++NumVectorized;
2302  }
2303  assert((!IntTy && !VecTy) || (IntTy && !VecTy) || (!IntTy && VecTy));
2304  }
2305 
2307  bool CanSROA = true;
2308  BeginOffset = I->beginOffset();
2309  EndOffset = I->endOffset();
2310  IsSplittable = I->isSplittable();
2311  IsSplit =
2312  BeginOffset < NewAllocaBeginOffset || EndOffset > NewAllocaEndOffset;
2313  LLVM_DEBUG(dbgs() << " rewriting " << (IsSplit ? "split " : ""));
2314  LLVM_DEBUG(AS.printSlice(dbgs(), I, ""));
2315  LLVM_DEBUG(dbgs() << "\n");
2316 
2317  // Compute the intersecting offset range.
2318  assert(BeginOffset < NewAllocaEndOffset);
2319  assert(EndOffset > NewAllocaBeginOffset);
2320  NewBeginOffset = std::max(BeginOffset, NewAllocaBeginOffset);
2321  NewEndOffset = std::min(EndOffset, NewAllocaEndOffset);
2322 
2323  SliceSize = NewEndOffset - NewBeginOffset;
2324 
2325  OldUse = I->getUse();
2326  OldPtr = cast<Instruction>(OldUse->get());
2327 
2328  Instruction *OldUserI = cast<Instruction>(OldUse->getUser());
2329  IRB.SetInsertPoint(OldUserI);
2330  IRB.SetCurrentDebugLocation(OldUserI->getDebugLoc());
2331  IRB.SetNamePrefix(Twine(NewAI.getName()) + "." + Twine(BeginOffset) + ".");
2332 
2333  CanSROA &= visit(cast<Instruction>(OldUse->getUser()));
2334  if (VecTy || IntTy)
2335  assert(CanSROA);
2336  return CanSROA;
2337  }
2338 
2339 private:
2340  // Make sure the other visit overloads are visible.
2341  using Base::visit;
2342 
2343  // Every instruction which can end up as a user must have a rewrite rule.
2344  bool visitInstruction(Instruction &I) {
2345  LLVM_DEBUG(dbgs() << " !!!! Cannot rewrite: " << I << "\n");
2346  llvm_unreachable("No rewrite rule for this instruction!");
2347  }
2348 
2349  Value *getNewAllocaSlicePtr(IRBuilderTy &IRB, Type *PointerTy) {
2350  // Note that the offset computation can use BeginOffset or NewBeginOffset
2351  // interchangeably for unsplit slices.
2352  assert(IsSplit || BeginOffset == NewBeginOffset);
2353  uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
2354 
2355 #ifndef NDEBUG
2356  StringRef OldName = OldPtr->getName();
2357  // Skip through the last '.sroa.' component of the name.
2358  size_t LastSROAPrefix = OldName.rfind(".sroa.");
2359  if (LastSROAPrefix != StringRef::npos) {
2360  OldName = OldName.substr(LastSROAPrefix + strlen(".sroa."));
2361  // Look for an SROA slice index.
2362  size_t IndexEnd = OldName.find_first_not_of("0123456789");
2363  if (IndexEnd != StringRef::npos && OldName[IndexEnd] == '.') {
2364  // Strip the index and look for the offset.
2365  OldName = OldName.substr(IndexEnd + 1);
2366  size_t OffsetEnd = OldName.find_first_not_of("0123456789");
2367  if (OffsetEnd != StringRef::npos && OldName[OffsetEnd] == '.')
2368  // Strip the offset.
2369  OldName = OldName.substr(OffsetEnd + 1);
2370  }
2371  }
2372  // Strip any SROA suffixes as well.
2373  OldName = OldName.substr(0, OldName.find(".sroa_"));
2374 #endif
2375 
2376  return getAdjustedPtr(IRB, DL, &NewAI,
2377  APInt(DL.getIndexTypeSizeInBits(PointerTy), Offset),
2378  PointerTy,
2379 #ifndef NDEBUG
2380  Twine(OldName) + "."
2381 #else
2382  Twine()
2383 #endif
2384  );
2385  }
2386 
2387  /// Compute suitable alignment to access this slice of the *new*
2388  /// alloca.
2389  ///
2390  /// You can optionally pass a type to this routine and if that type's ABI
2391  /// alignment is itself suitable, this will return zero.
2392  unsigned getSliceAlign(Type *Ty = nullptr) {
2393  unsigned NewAIAlign = NewAI.getAlignment();
2394  if (!NewAIAlign)
2395  NewAIAlign = DL.getABITypeAlignment(NewAI.getAllocatedType());
2396  unsigned Align =
2397  MinAlign(NewAIAlign, NewBeginOffset - NewAllocaBeginOffset);
2398  return (Ty && Align == DL.getABITypeAlignment(Ty)) ? 0 : Align;
2399  }
2400 
2401  unsigned getIndex(uint64_t Offset) {
2402  assert(VecTy && "Can only call getIndex when rewriting a vector");
2403  uint64_t RelOffset = Offset - NewAllocaBeginOffset;
2404  assert(RelOffset / ElementSize < UINT32_MAX && "Index out of bounds");
2405  uint32_t Index = RelOffset / ElementSize;
2406  assert(Index * ElementSize == RelOffset);
2407  return Index;
2408  }
2409 
2410  void deleteIfTriviallyDead(Value *V) {
2411  Instruction *I = cast<Instruction>(V);
2413  Pass.DeadInsts.insert(I);
2414  }
2415 
2416  Value *rewriteVectorizedLoadInst() {
2417  unsigned BeginIndex = getIndex(NewBeginOffset);
2418  unsigned EndIndex = getIndex(NewEndOffset);
2419  assert(EndIndex > BeginIndex && "Empty vector!");
2420 
2421  Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
2422  return extractVector(IRB, V, BeginIndex, EndIndex, "vec");
2423  }
2424 
2425  Value *rewriteIntegerLoad(LoadInst &LI) {
2426  assert(IntTy && "We cannot insert an integer to the alloca");
2427  assert(!LI.isVolatile());
2428  Value *V = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
2429  V = convertValue(DL, IRB, V, IntTy);
2430  assert(NewBeginOffset >= NewAllocaBeginOffset && "Out of bounds offset");
2431  uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
2432  if (Offset > 0 || NewEndOffset < NewAllocaEndOffset) {
2433  IntegerType *ExtractTy = Type::getIntNTy(LI.getContext(), SliceSize * 8);
2434  V = extractInteger(DL, IRB, V, ExtractTy, Offset, "extract");
2435  }
2436  // It is possible that the extracted type is not the load type. This
2437  // happens if there is a load past the end of the alloca, and as
2438  // a consequence the slice is narrower but still a candidate for integer
2439  // lowering. To handle this case, we just zero extend the extracted
2440  // integer.
2441  assert(cast<IntegerType>(LI.getType())->getBitWidth() >= SliceSize * 8 &&
2442  "Can only handle an extract for an overly wide load");
2443  if (cast<IntegerType>(LI.getType())->getBitWidth() > SliceSize * 8)
2444  V = IRB.CreateZExt(V, LI.getType());
2445  return V;
2446  }
2447 
2448  bool visitLoadInst(LoadInst &LI) {
2449  LLVM_DEBUG(dbgs() << " original: " << LI << "\n");
2450  Value *OldOp = LI.getOperand(0);
2451  assert(OldOp == OldPtr);
2452 
2453  AAMDNodes AATags;
2454  LI.getAAMetadata(AATags);
2455 
2456  unsigned AS = LI.getPointerAddressSpace();
2457 
2458  Type *TargetTy = IsSplit ? Type::getIntNTy(LI.getContext(), SliceSize * 8)
2459  : LI.getType();
2460  const bool IsLoadPastEnd = DL.getTypeStoreSize(TargetTy) > SliceSize;
2461  bool IsPtrAdjusted = false;
2462  Value *V;
2463  if (VecTy) {
2464  V = rewriteVectorizedLoadInst();
2465  } else if (IntTy && LI.getType()->isIntegerTy()) {
2466  V = rewriteIntegerLoad(LI);
2467  } else if (NewBeginOffset == NewAllocaBeginOffset &&
2468  NewEndOffset == NewAllocaEndOffset &&
2469  (canConvertValue(DL, NewAllocaTy, TargetTy) ||
2470  (IsLoadPastEnd && NewAllocaTy->isIntegerTy() &&
2471  TargetTy->isIntegerTy()))) {
2472  LoadInst *NewLI = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(),
2473  LI.isVolatile(), LI.getName());
2474  if (AATags)
2475  NewLI->setAAMetadata(AATags);
2476  if (LI.isVolatile())
2477  NewLI->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
2478 
2479  // Any !nonnull metadata or !range metadata on the old load is also valid
2480  // on the new load. This is even true in some cases even when the loads
2481  // are different types, for example by mapping !nonnull metadata to
2482  // !range metadata by modeling the null pointer constant converted to the
2483  // integer type.
2484  // FIXME: Add support for range metadata here. Currently the utilities
2485  // for this don't propagate range metadata in trivial cases from one
2486  // integer load to another, don't handle non-addrspace-0 null pointers
2487  // correctly, and don't have any support for mapping ranges as the
2488  // integer type becomes winder or narrower.
2490  copyNonnullMetadata(LI, N, *NewLI);
2491 
2492  // Try to preserve nonnull metadata
2493  V = NewLI;
2494 
2495  // If this is an integer load past the end of the slice (which means the
2496  // bytes outside the slice are undef or this load is dead) just forcibly
2497  // fix the integer size with correct handling of endianness.
2498  if (auto *AITy = dyn_cast<IntegerType>(NewAllocaTy))
2499  if (auto *TITy = dyn_cast<IntegerType>(TargetTy))
2500  if (AITy->getBitWidth() < TITy->getBitWidth()) {
2501  V = IRB.CreateZExt(V, TITy, "load.ext");
2502  if (DL.isBigEndian())
2503  V = IRB.CreateShl(V, TITy->getBitWidth() - AITy->getBitWidth(),
2504  "endian_shift");
2505  }
2506  } else {
2507  Type *LTy = TargetTy->getPointerTo(AS);
2508  LoadInst *NewLI = IRB.CreateAlignedLoad(getNewAllocaSlicePtr(IRB, LTy),
2509  getSliceAlign(TargetTy),
2510  LI.isVolatile(), LI.getName());
2511  if (AATags)
2512  NewLI->setAAMetadata(AATags);
2513  if (LI.isVolatile())
2514  NewLI->setAtomic(LI.getOrdering(), LI.getSyncScopeID());
2515 
2516  V = NewLI;
2517  IsPtrAdjusted = true;
2518  }
2519  V = convertValue(DL, IRB, V, TargetTy);
2520 
2521  if (IsSplit) {
2522  assert(!LI.isVolatile());
2523  assert(LI.getType()->isIntegerTy() &&
2524  "Only integer type loads and stores are split");
2525  assert(SliceSize < DL.getTypeStoreSize(LI.getType()) &&
2526  "Split load isn't smaller than original load");
2527  assert(LI.getType()->getIntegerBitWidth() ==
2528  DL.getTypeStoreSizeInBits(LI.getType()) &&
2529  "Non-byte-multiple bit width");
2530  // Move the insertion point just past the load so that we can refer to it.
2531  IRB.SetInsertPoint(&*std::next(BasicBlock::iterator(&LI)));
2532  // Create a placeholder value with the same type as LI to use as the
2533  // basis for the new value. This allows us to replace the uses of LI with
2534  // the computed value, and then replace the placeholder with LI, leaving
2535  // LI only used for this computation.
2536  Value *Placeholder =
2537  new LoadInst(UndefValue::get(LI.getType()->getPointerTo(AS)));
2538  V = insertInteger(DL, IRB, Placeholder, V, NewBeginOffset - BeginOffset,
2539  "insert");
2540  LI.replaceAllUsesWith(V);
2541  Placeholder->replaceAllUsesWith(&LI);
2542  Placeholder->deleteValue();
2543  } else {
2544  LI.replaceAllUsesWith(V);
2545  }
2546 
2547  Pass.DeadInsts.insert(&LI);
2548  deleteIfTriviallyDead(OldOp);
2549  LLVM_DEBUG(dbgs() << " to: " << *V << "\n");
2550  return !LI.isVolatile() && !IsPtrAdjusted;
2551  }
2552 
2553  bool rewriteVectorizedStoreInst(Value *V, StoreInst &SI, Value *OldOp,
2554  AAMDNodes AATags) {
2555  if (V->getType() != VecTy) {
2556  unsigned BeginIndex = getIndex(NewBeginOffset);
2557  unsigned EndIndex = getIndex(NewEndOffset);
2558  assert(EndIndex > BeginIndex && "Empty vector!");
2559  unsigned NumElements = EndIndex - BeginIndex;
2560  assert(NumElements <= VecTy->getNumElements() && "Too many elements!");
2561  Type *SliceTy = (NumElements == 1)
2562  ? ElementTy
2563  : VectorType::get(ElementTy, NumElements);
2564  if (V->getType() != SliceTy)
2565  V = convertValue(DL, IRB, V, SliceTy);
2566 
2567  // Mix in the existing elements.
2568  Value *Old = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
2569  V = insertVector(IRB, Old, V, BeginIndex, "vec");
2570  }
2571  StoreInst *Store = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment());
2572  if (AATags)
2573  Store->setAAMetadata(AATags);
2574  Pass.DeadInsts.insert(&SI);
2575 
2576  LLVM_DEBUG(dbgs() << " to: " << *Store << "\n");
2577  return true;
2578  }
2579 
2580  bool rewriteIntegerStore(Value *V, StoreInst &SI, AAMDNodes AATags) {
2581  assert(IntTy && "We cannot extract an integer from the alloca");
2582  assert(!SI.isVolatile());
2583  if (DL.getTypeSizeInBits(V->getType()) != IntTy->getBitWidth()) {
2584  Value *Old =
2585  IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
2586  Old = convertValue(DL, IRB, Old, IntTy);
2587  assert(BeginOffset >= NewAllocaBeginOffset && "Out of bounds offset");
2588  uint64_t Offset = BeginOffset - NewAllocaBeginOffset;
2589  V = insertInteger(DL, IRB, Old, SI.getValueOperand(), Offset, "insert");
2590  }
2591  V = convertValue(DL, IRB, V, NewAllocaTy);
2592  StoreInst *Store = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment());
2595  if (AATags)
2596  Store->setAAMetadata(AATags);
2597  Pass.DeadInsts.insert(&SI);
2598  LLVM_DEBUG(dbgs() << " to: " << *Store << "\n");
2599  return true;
2600  }
2601 
2602  bool visitStoreInst(StoreInst &SI) {
2603  LLVM_DEBUG(dbgs() << " original: " << SI << "\n");
2604  Value *OldOp = SI.getOperand(1);
2605  assert(OldOp == OldPtr);
2606 
2607  AAMDNodes AATags;
2608  SI.getAAMetadata(AATags);
2609 
2610  Value *V = SI.getValueOperand();
2611 
2612  // Strip all inbounds GEPs and pointer casts to try to dig out any root
2613  // alloca that should be re-examined after promoting this alloca.
2614  if (V->getType()->isPointerTy())
2615  if (AllocaInst *AI = dyn_cast<AllocaInst>(V->stripInBoundsOffsets()))
2616  Pass.PostPromotionWorklist.insert(AI);
2617 
2618  if (SliceSize < DL.getTypeStoreSize(V->getType())) {
2619  assert(!SI.isVolatile());
2620  assert(V->getType()->isIntegerTy() &&
2621  "Only integer type loads and stores are split");
2622  assert(V->getType()->getIntegerBitWidth() ==
2623  DL.getTypeStoreSizeInBits(V->getType()) &&
2624  "Non-byte-multiple bit width");
2625  IntegerType *NarrowTy = Type::getIntNTy(SI.getContext(), SliceSize * 8);
2626  V = extractInteger(DL, IRB, V, NarrowTy, NewBeginOffset - BeginOffset,
2627  "extract");
2628  }
2629 
2630  if (VecTy)
2631  return rewriteVectorizedStoreInst(V, SI, OldOp, AATags);
2632  if (IntTy && V->getType()->isIntegerTy())
2633  return rewriteIntegerStore(V, SI, AATags);
2634 
2635  const bool IsStorePastEnd = DL.getTypeStoreSize(V->getType()) > SliceSize;
2636  StoreInst *NewSI;
2637  if (NewBeginOffset == NewAllocaBeginOffset &&
2638  NewEndOffset == NewAllocaEndOffset &&
2639  (canConvertValue(DL, V->getType(), NewAllocaTy) ||
2640  (IsStorePastEnd && NewAllocaTy->isIntegerTy() &&
2641  V->getType()->isIntegerTy()))) {
2642  // If this is an integer store past the end of slice (and thus the bytes
2643  // past that point are irrelevant or this is unreachable), truncate the
2644  // value prior to storing.
2645  if (auto *VITy = dyn_cast<IntegerType>(V->getType()))
2646  if (auto *AITy = dyn_cast<IntegerType>(NewAllocaTy))
2647  if (VITy->getBitWidth() > AITy->getBitWidth()) {
2648  if (DL.isBigEndian())
2649  V = IRB.CreateLShr(V, VITy->getBitWidth() - AITy->getBitWidth(),
2650  "endian_shift");
2651  V = IRB.CreateTrunc(V, AITy, "load.trunc");
2652  }
2653 
2654  V = convertValue(DL, IRB, V, NewAllocaTy);
2655  NewSI = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment(),
2656  SI.isVolatile());
2657  } else {
2658  unsigned AS = SI.getPointerAddressSpace();
2659  Value *NewPtr = getNewAllocaSlicePtr(IRB, V->getType()->getPointerTo(AS));
2660  NewSI = IRB.CreateAlignedStore(V, NewPtr, getSliceAlign(V->getType()),
2661  SI.isVolatile());
2662  }
2665  if (AATags)
2666  NewSI->setAAMetadata(AATags);
2667  if (SI.isVolatile())
2668  NewSI->setAtomic(SI.getOrdering(), SI.getSyncScopeID());
2669  Pass.DeadInsts.insert(&SI);
2670  deleteIfTriviallyDead(OldOp);
2671 
2672  LLVM_DEBUG(dbgs() << " to: " << *NewSI << "\n");
2673  return NewSI->getPointerOperand() == &NewAI && !SI.isVolatile();
2674  }
2675 
2676  /// Compute an integer value from splatting an i8 across the given
2677  /// number of bytes.
2678  ///
2679  /// Note that this routine assumes an i8 is a byte. If that isn't true, don't
2680  /// call this routine.
2681  /// FIXME: Heed the advice above.
2682  ///
2683  /// \param V The i8 value to splat.
2684  /// \param Size The number of bytes in the output (assuming i8 is one byte)
2685  Value *getIntegerSplat(Value *V, unsigned Size) {
2686  assert(Size > 0 && "Expected a positive number of bytes.");
2687  IntegerType *VTy = cast<IntegerType>(V->getType());
2688  assert(VTy->getBitWidth() == 8 && "Expected an i8 value for the byte");
2689  if (Size == 1)
2690  return V;
2691 
2692  Type *SplatIntTy = Type::getIntNTy(VTy->getContext(), Size * 8);
2693  V = IRB.CreateMul(
2694  IRB.CreateZExt(V, SplatIntTy, "zext"),
2696  Constant::getAllOnesValue(SplatIntTy),
2698  SplatIntTy)),
2699  "isplat");
2700  return V;
2701  }
2702 
2703  /// Compute a vector splat for a given element value.
2704  Value *getVectorSplat(Value *V, unsigned NumElements) {
2705  V = IRB.CreateVectorSplat(NumElements, V, "vsplat");
2706  LLVM_DEBUG(dbgs() << " splat: " << *V << "\n");
2707  return V;
2708  }
2709 
2710  bool visitMemSetInst(MemSetInst &II) {
2711  LLVM_DEBUG(dbgs() << " original: " << II << "\n");
2712  assert(II.getRawDest() == OldPtr);
2713 
2714  AAMDNodes AATags;
2715  II.getAAMetadata(AATags);
2716 
2717  // If the memset has a variable size, it cannot be split, just adjust the
2718  // pointer to the new alloca.
2719  if (!isa<Constant>(II.getLength())) {
2720  assert(!IsSplit);
2721  assert(NewBeginOffset == BeginOffset);
2722  II.setDest(getNewAllocaSlicePtr(IRB, OldPtr->getType()));
2723  II.setDestAlignment(getSliceAlign());
2724 
2725  deleteIfTriviallyDead(OldPtr);
2726  return false;
2727  }
2728 
2729  // Record this instruction for deletion.
2730  Pass.DeadInsts.insert(&II);
2731 
2732  Type *AllocaTy = NewAI.getAllocatedType();
2733  Type *ScalarTy = AllocaTy->getScalarType();
2734 
2735  // If this doesn't map cleanly onto the alloca type, and that type isn't
2736  // a single value type, just emit a memset.
2737  if (!VecTy && !IntTy &&
2738  (BeginOffset > NewAllocaBeginOffset || EndOffset < NewAllocaEndOffset ||
2739  SliceSize != DL.getTypeStoreSize(AllocaTy) ||
2740  !AllocaTy->isSingleValueType() ||
2741  !DL.isLegalInteger(DL.getTypeSizeInBits(ScalarTy)) ||
2742  DL.getTypeSizeInBits(ScalarTy) % 8 != 0)) {
2743  Type *SizeTy = II.getLength()->getType();
2744  Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset);
2745  CallInst *New = IRB.CreateMemSet(
2746  getNewAllocaSlicePtr(IRB, OldPtr->getType()), II.getValue(), Size,
2747  getSliceAlign(), II.isVolatile());
2748  if (AATags)
2749  New->setAAMetadata(AATags);
2750  LLVM_DEBUG(dbgs() << " to: " << *New << "\n");
2751  return false;
2752  }
2753 
2754  // If we can represent this as a simple value, we have to build the actual
2755  // value to store, which requires expanding the byte present in memset to
2756  // a sensible representation for the alloca type. This is essentially
2757  // splatting the byte to a sufficiently wide integer, splatting it across
2758  // any desired vector width, and bitcasting to the final type.
2759  Value *V;
2760 
2761  if (VecTy) {
2762  // If this is a memset of a vectorized alloca, insert it.
2763  assert(ElementTy == ScalarTy);
2764 
2765  unsigned BeginIndex = getIndex(NewBeginOffset);
2766  unsigned EndIndex = getIndex(NewEndOffset);
2767  assert(EndIndex > BeginIndex && "Empty vector!");
2768  unsigned NumElements = EndIndex - BeginIndex;
2769  assert(NumElements <= VecTy->getNumElements() && "Too many elements!");
2770 
2771  Value *Splat =
2772  getIntegerSplat(II.getValue(), DL.getTypeSizeInBits(ElementTy) / 8);
2773  Splat = convertValue(DL, IRB, Splat, ElementTy);
2774  if (NumElements > 1)
2775  Splat = getVectorSplat(Splat, NumElements);
2776 
2777  Value *Old =
2778  IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
2779  V = insertVector(IRB, Old, Splat, BeginIndex, "vec");
2780  } else if (IntTy) {
2781  // If this is a memset on an alloca where we can widen stores, insert the
2782  // set integer.
2783  assert(!II.isVolatile());
2784 
2785  uint64_t Size = NewEndOffset - NewBeginOffset;
2786  V = getIntegerSplat(II.getValue(), Size);
2787 
2788  if (IntTy && (BeginOffset != NewAllocaBeginOffset ||
2789  EndOffset != NewAllocaBeginOffset)) {
2790  Value *Old =
2791  IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
2792  Old = convertValue(DL, IRB, Old, IntTy);
2793  uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
2794  V = insertInteger(DL, IRB, Old, V, Offset, "insert");
2795  } else {
2796  assert(V->getType() == IntTy &&
2797  "Wrong type for an alloca wide integer!");
2798  }
2799  V = convertValue(DL, IRB, V, AllocaTy);
2800  } else {
2801  // Established these invariants above.
2802  assert(NewBeginOffset == NewAllocaBeginOffset);
2803  assert(NewEndOffset == NewAllocaEndOffset);
2804 
2805  V = getIntegerSplat(II.getValue(), DL.getTypeSizeInBits(ScalarTy) / 8);
2806  if (VectorType *AllocaVecTy = dyn_cast<VectorType>(AllocaTy))
2807  V = getVectorSplat(V, AllocaVecTy->getNumElements());
2808 
2809  V = convertValue(DL, IRB, V, AllocaTy);
2810  }
2811 
2812  StoreInst *New = IRB.CreateAlignedStore(V, &NewAI, NewAI.getAlignment(),
2813  II.isVolatile());
2814  if (AATags)
2815  New->setAAMetadata(AATags);
2816  LLVM_DEBUG(dbgs() << " to: " << *New << "\n");
2817  return !II.isVolatile();
2818  }
2819 
2820  bool visitMemTransferInst(MemTransferInst &II) {
2821  // Rewriting of memory transfer instructions can be a bit tricky. We break
2822  // them into two categories: split intrinsics and unsplit intrinsics.
2823 
2824  LLVM_DEBUG(dbgs() << " original: " << II << "\n");
2825 
2826  AAMDNodes AATags;
2827  II.getAAMetadata(AATags);
2828 
2829  bool IsDest = &II.getRawDestUse() == OldUse;
2830  assert((IsDest && II.getRawDest() == OldPtr) ||
2831  (!IsDest && II.getRawSource() == OldPtr));
2832 
2833  unsigned SliceAlign = getSliceAlign();
2834 
2835  // For unsplit intrinsics, we simply modify the source and destination
2836  // pointers in place. This isn't just an optimization, it is a matter of
2837  // correctness. With unsplit intrinsics we may be dealing with transfers
2838  // within a single alloca before SROA ran, or with transfers that have
2839  // a variable length. We may also be dealing with memmove instead of
2840  // memcpy, and so simply updating the pointers is the necessary for us to
2841  // update both source and dest of a single call.
2842  if (!IsSplittable) {
2843  Value *AdjustedPtr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
2844  if (IsDest) {
2845  II.setDest(AdjustedPtr);
2846  II.setDestAlignment(SliceAlign);
2847  }
2848  else {
2849  II.setSource(AdjustedPtr);
2850  II.setSourceAlignment(SliceAlign);
2851  }
2852 
2853  LLVM_DEBUG(dbgs() << " to: " << II << "\n");
2854  deleteIfTriviallyDead(OldPtr);
2855  return false;
2856  }
2857  // For split transfer intrinsics we have an incredibly useful assurance:
2858  // the source and destination do not reside within the same alloca, and at
2859  // least one of them does not escape. This means that we can replace
2860  // memmove with memcpy, and we don't need to worry about all manner of
2861  // downsides to splitting and transforming the operations.
2862 
2863  // If this doesn't map cleanly onto the alloca type, and that type isn't
2864  // a single value type, just emit a memcpy.
2865  bool EmitMemCpy =
2866  !VecTy && !IntTy &&
2867  (BeginOffset > NewAllocaBeginOffset || EndOffset < NewAllocaEndOffset ||
2868  SliceSize != DL.getTypeStoreSize(NewAI.getAllocatedType()) ||
2869  !NewAI.getAllocatedType()->isSingleValueType());
2870 
2871  // If we're just going to emit a memcpy, the alloca hasn't changed, and the
2872  // size hasn't been shrunk based on analysis of the viable range, this is
2873  // a no-op.
2874  if (EmitMemCpy && &OldAI == &NewAI) {
2875  // Ensure the start lines up.
2876  assert(NewBeginOffset == BeginOffset);
2877 
2878  // Rewrite the size as needed.
2879  if (NewEndOffset != EndOffset)
2881  NewEndOffset - NewBeginOffset));
2882  return false;
2883  }
2884  // Record this instruction for deletion.
2885  Pass.DeadInsts.insert(&II);
2886 
2887  // Strip all inbounds GEPs and pointer casts to try to dig out any root
2888  // alloca that should be re-examined after rewriting this instruction.
2889  Value *OtherPtr = IsDest ? II.getRawSource() : II.getRawDest();
2890  if (AllocaInst *AI =
2891  dyn_cast<AllocaInst>(OtherPtr->stripInBoundsOffsets())) {
2892  assert(AI != &OldAI && AI != &NewAI &&
2893  "Splittable transfers cannot reach the same alloca on both ends.");
2894  Pass.Worklist.insert(AI);
2895  }
2896 
2897  Type *OtherPtrTy = OtherPtr->getType();
2898  unsigned OtherAS = OtherPtrTy->getPointerAddressSpace();
2899 
2900  // Compute the relative offset for the other pointer within the transfer.
2901  unsigned OffsetWidth = DL.getIndexSizeInBits(OtherAS);
2902  APInt OtherOffset(OffsetWidth, NewBeginOffset - BeginOffset);
2903  unsigned OtherAlign =
2904  IsDest ? II.getSourceAlignment() : II.getDestAlignment();
2905  OtherAlign = MinAlign(OtherAlign ? OtherAlign : 1,
2906  OtherOffset.zextOrTrunc(64).getZExtValue());
2907 
2908  if (EmitMemCpy) {
2909  // Compute the other pointer, folding as much as possible to produce
2910  // a single, simple GEP in most cases.
2911  OtherPtr = getAdjustedPtr(IRB, DL, OtherPtr, OtherOffset, OtherPtrTy,
2912  OtherPtr->getName() + ".");
2913 
2914  Value *OurPtr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
2915  Type *SizeTy = II.getLength()->getType();
2916  Constant *Size = ConstantInt::get(SizeTy, NewEndOffset - NewBeginOffset);
2917 
2918  Value *DestPtr, *SrcPtr;
2919  unsigned DestAlign, SrcAlign;
2920  // Note: IsDest is true iff we're copying into the new alloca slice
2921  if (IsDest) {
2922  DestPtr = OurPtr;
2923  DestAlign = SliceAlign;
2924  SrcPtr = OtherPtr;
2925  SrcAlign = OtherAlign;
2926  } else {
2927  DestPtr = OtherPtr;
2928  DestAlign = OtherAlign;
2929  SrcPtr = OurPtr;
2930  SrcAlign = SliceAlign;
2931  }
2932  CallInst *New = IRB.CreateMemCpy(DestPtr, DestAlign, SrcPtr, SrcAlign,
2933  Size, II.isVolatile());
2934  if (AATags)
2935  New->setAAMetadata(AATags);
2936  LLVM_DEBUG(dbgs() << " to: " << *New << "\n");
2937  return false;
2938  }
2939 
2940  bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset &&
2941  NewEndOffset == NewAllocaEndOffset;
2942  uint64_t Size = NewEndOffset - NewBeginOffset;
2943  unsigned BeginIndex = VecTy ? getIndex(NewBeginOffset) : 0;
2944  unsigned EndIndex = VecTy ? getIndex(NewEndOffset) : 0;
2945  unsigned NumElements = EndIndex - BeginIndex;
2946  IntegerType *SubIntTy =
2947  IntTy ? Type::getIntNTy(IntTy->getContext(), Size * 8) : nullptr;
2948 
2949  // Reset the other pointer type to match the register type we're going to
2950  // use, but using the address space of the original other pointer.
2951  if (VecTy && !IsWholeAlloca) {
2952  if (NumElements == 1)
2953  OtherPtrTy = VecTy->getElementType();
2954  else
2955  OtherPtrTy = VectorType::get(VecTy->getElementType(), NumElements);
2956 
2957  OtherPtrTy = OtherPtrTy->getPointerTo(OtherAS);
2958  } else if (IntTy && !IsWholeAlloca) {
2959  OtherPtrTy = SubIntTy->getPointerTo(OtherAS);
2960  } else {
2961  OtherPtrTy = NewAllocaTy->getPointerTo(OtherAS);
2962  }
2963 
2964  Value *SrcPtr = getAdjustedPtr(IRB, DL, OtherPtr, OtherOffset, OtherPtrTy,
2965  OtherPtr->getName() + ".");
2966  unsigned SrcAlign = OtherAlign;
2967  Value *DstPtr = &NewAI;
2968  unsigned DstAlign = SliceAlign;
2969  if (!IsDest) {
2970  std::swap(SrcPtr, DstPtr);
2971  std::swap(SrcAlign, DstAlign);
2972  }
2973 
2974  Value *Src;
2975  if (VecTy && !IsWholeAlloca && !IsDest) {
2976  Src = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
2977  Src = extractVector(IRB, Src, BeginIndex, EndIndex, "vec");
2978  } else if (IntTy && !IsWholeAlloca && !IsDest) {
2979  Src = IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "load");
2980  Src = convertValue(DL, IRB, Src, IntTy);
2981  uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
2982  Src = extractInteger(DL, IRB, Src, SubIntTy, Offset, "extract");
2983  } else {
2984  LoadInst *Load = IRB.CreateAlignedLoad(SrcPtr, SrcAlign, II.isVolatile(),
2985  "copyload");
2986  if (AATags)
2987  Load->setAAMetadata(AATags);
2988  Src = Load;
2989  }
2990 
2991  if (VecTy && !IsWholeAlloca && IsDest) {
2992  Value *Old =
2993  IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
2994  Src = insertVector(IRB, Old, Src, BeginIndex, "vec");
2995  } else if (IntTy && !IsWholeAlloca && IsDest) {
2996  Value *Old =
2997  IRB.CreateAlignedLoad(&NewAI, NewAI.getAlignment(), "oldload");
2998  Old = convertValue(DL, IRB, Old, IntTy);
2999  uint64_t Offset = NewBeginOffset - NewAllocaBeginOffset;
3000  Src = insertInteger(DL, IRB, Old, Src, Offset, "insert");
3001  Src = convertValue(DL, IRB, Src, NewAllocaTy);
3002  }
3003 
3004  StoreInst *Store = cast<StoreInst>(
3005  IRB.CreateAlignedStore(Src, DstPtr, DstAlign, II.isVolatile()));
3006  if (AATags)
3007  Store->setAAMetadata(AATags);
3008  LLVM_DEBUG(dbgs() << " to: " << *Store << "\n");
3009  return !II.isVolatile();
3010  }
3011 
3012  bool visitIntrinsicInst(IntrinsicInst &II) {
3014  LLVM_DEBUG(dbgs() << " original: " << II << "\n");
3015  assert(II.getArgOperand(1) == OldPtr);
3016 
3017  // Record this instruction for deletion.
3018  Pass.DeadInsts.insert(&II);
3019 
3020  // Lifetime intrinsics are only promotable if they cover the whole alloca.
3021  // Therefore, we drop lifetime intrinsics which don't cover the whole
3022  // alloca.
3023  // (In theory, intrinsics which partially cover an alloca could be
3024  // promoted, but PromoteMemToReg doesn't handle that case.)
3025  // FIXME: Check whether the alloca is promotable before dropping the
3026  // lifetime intrinsics?
3027  if (NewBeginOffset != NewAllocaBeginOffset ||
3028  NewEndOffset != NewAllocaEndOffset)
3029  return true;
3030 
3031  ConstantInt *Size =
3032  ConstantInt::get(cast<IntegerType>(II.getArgOperand(0)->getType()),
3033  NewEndOffset - NewBeginOffset);
3034  // Lifetime intrinsics always expect an i8* so directly get such a pointer
3035  // for the new alloca slice.
3036  Type *PointerTy = IRB.getInt8PtrTy(OldPtr->getType()->getPointerAddressSpace());
3037  Value *Ptr = getNewAllocaSlicePtr(IRB, PointerTy);
3038  Value *New;
3039  if (II.getIntrinsicID() == Intrinsic::lifetime_start)
3040  New = IRB.CreateLifetimeStart(Ptr, Size);
3041  else
3042  New = IRB.CreateLifetimeEnd(Ptr, Size);
3043 
3044  (void)New;
3045  LLVM_DEBUG(dbgs() << " to: " << *New << "\n");
3046 
3047  return true;
3048  }
3049 
3050  void fixLoadStoreAlign(Instruction &Root) {
3051  // This algorithm implements the same visitor loop as
3052  // hasUnsafePHIOrSelectUse, and fixes the alignment of each load
3053  // or store found.
3056  Visited.insert(&Root);
3057  Uses.push_back(&Root);
3058  do {
3059  Instruction *I = Uses.pop_back_val();
3060 
3061  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
3062  unsigned LoadAlign = LI->getAlignment();
3063  if (!LoadAlign)
3064  LoadAlign = DL.getABITypeAlignment(LI->getType());
3065  LI->setAlignment(std::min(LoadAlign, getSliceAlign()));
3066  continue;
3067  }
3068  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
3069  unsigned StoreAlign = SI->getAlignment();
3070  if (!StoreAlign) {
3071  Value *Op = SI->getOperand(0);
3072  StoreAlign = DL.getABITypeAlignment(Op->getType());
3073  }
3074  SI->setAlignment(std::min(StoreAlign, getSliceAlign()));
3075  continue;
3076  }
3077 
3078  assert(isa<BitCastInst>(I) || isa<PHINode>(I) ||
3079  isa<SelectInst>(I) || isa<GetElementPtrInst>(I));
3080  for (User *U : I->users())
3081  if (Visited.insert(cast<Instruction>(U)).second)
3082  Uses.push_back(cast<Instruction>(U));
3083  } while (!Uses.empty());
3084  }
3085 
3086  bool visitPHINode(PHINode &PN) {
3087  LLVM_DEBUG(dbgs() << " original: " << PN << "\n");
3088  assert(BeginOffset >= NewAllocaBeginOffset && "PHIs are unsplittable");
3089  assert(EndOffset <= NewAllocaEndOffset && "PHIs are unsplittable");
3090 
3091  // We would like to compute a new pointer in only one place, but have it be
3092  // as local as possible to the PHI. To do that, we re-use the location of
3093  // the old pointer, which necessarily must be in the right position to
3094  // dominate the PHI.
3095  IRBuilderTy PtrBuilder(IRB);
3096  if (isa<PHINode>(OldPtr))
3097  PtrBuilder.SetInsertPoint(&*OldPtr->getParent()->getFirstInsertionPt());
3098  else
3099  PtrBuilder.SetInsertPoint(OldPtr);
3100  PtrBuilder.SetCurrentDebugLocation(OldPtr->getDebugLoc());
3101 
3102  Value *NewPtr = getNewAllocaSlicePtr(PtrBuilder, OldPtr->getType());
3103  // Replace the operands which were using the old pointer.
3104  std::replace(PN.op_begin(), PN.op_end(), cast<Value>(OldPtr), NewPtr);
3105 
3106  LLVM_DEBUG(dbgs() << " to: " << PN << "\n");
3107  deleteIfTriviallyDead(OldPtr);
3108 
3109  // Fix the alignment of any loads or stores using this PHI node.
3110  fixLoadStoreAlign(PN);
3111 
3112  // PHIs can't be promoted on their own, but often can be speculated. We
3113  // check the speculation outside of the rewriter so that we see the
3114  // fully-rewritten alloca.
3115  PHIUsers.insert(&PN);
3116  return true;
3117  }
3118 
3119  bool visitSelectInst(SelectInst &SI) {
3120  LLVM_DEBUG(dbgs() << " original: " << SI << "\n");
3121  assert((SI.getTrueValue() == OldPtr || SI.getFalseValue() == OldPtr) &&
3122  "Pointer isn't an operand!");
3123  assert(BeginOffset >= NewAllocaBeginOffset && "Selects are unsplittable");
3124  assert(EndOffset <= NewAllocaEndOffset && "Selects are unsplittable");
3125 
3126  Value *NewPtr = getNewAllocaSlicePtr(IRB, OldPtr->getType());
3127  // Replace the operands which were using the old pointer.
3128  if (SI.getOperand(1) == OldPtr)
3129  SI.setOperand(1, NewPtr);
3130  if (SI.getOperand(2) == OldPtr)
3131  SI.setOperand(2, NewPtr);
3132 
3133  LLVM_DEBUG(dbgs() << " to: " << SI << "\n");
3134  deleteIfTriviallyDead(OldPtr);
3135 
3136  // Fix the alignment of any loads or stores using this select.
3137  fixLoadStoreAlign(SI);
3138 
3139  // Selects can't be promoted on their own, but often can be speculated. We
3140  // check the speculation outside of the rewriter so that we see the
3141  // fully-rewritten alloca.
3142  SelectUsers.insert(&SI);
3143  return true;
3144  }
3145 };
3146 
3147 namespace {
3148 
3149 /// Visitor to rewrite aggregate loads and stores as scalar.
3150 ///
3151 /// This pass aggressively rewrites all aggregate loads and stores on
3152 /// a particular pointer (or any pointer derived from it which we can identify)
3153 /// with scalar loads and stores.
3154 class AggLoadStoreRewriter : public InstVisitor<AggLoadStoreRewriter, bool> {
3155  // Befriend the base class so it can delegate to private visit methods.
3156  friend class InstVisitor<AggLoadStoreRewriter, bool>;
3157 
3158  /// Queue of pointer uses to analyze and potentially rewrite.
3159  SmallVector<Use *, 8> Queue;
3160 
3161  /// Set to prevent us from cycling with phi nodes and loops.
3162  SmallPtrSet<User *, 8> Visited;
3163 
3164  /// The current pointer use being rewritten. This is used to dig up the used
3165  /// value (as opposed to the user).
3166  Use *U;
3167 
3168  /// Used to calculate offsets, and hence alignment, of subobjects.
3169  const DataLayout &DL;
3170 
3171 public:
3172  AggLoadStoreRewriter(const DataLayout &DL) : DL(DL) {}
3173 
3174  /// Rewrite loads and stores through a pointer and all pointers derived from
3175  /// it.
3176  bool rewrite(Instruction &I) {
3177  LLVM_DEBUG(dbgs() << " Rewriting FCA loads and stores...\n");
3178  enqueueUsers(I);
3179  bool Changed = false;
3180  while (!Queue.empty()) {
3181  U = Queue.pop_back_val();
3182  Changed |= visit(cast<Instruction>(U->getUser()));
3183  }
3184  return Changed;
3185  }
3186 
3187 private:
3188  /// Enqueue all the users of the given instruction for further processing.
3189  /// This uses a set to de-duplicate users.
3190  void enqueueUsers(Instruction &I) {
3191  for (Use &U : I.uses())
3192  if (Visited.insert(U.getUser()).second)
3193  Queue.push_back(&U);
3194  }
3195 
3196  // Conservative default is to not rewrite anything.
3197  bool visitInstruction(Instruction &I) { return false; }
3198 
3199  /// Generic recursive split emission class.
3200  template <typename Derived> class OpSplitter {
3201  protected:
3202  /// The builder used to form new instructions.
3203  IRBuilderTy IRB;
3204 
3205  /// The indices which to be used with insert- or extractvalue to select the
3206  /// appropriate value within the aggregate.
3207  SmallVector<unsigned, 4> Indices;
3208 
3209  /// The indices to a GEP instruction which will move Ptr to the correct slot
3210  /// within the aggregate.
3211  SmallVector<Value *, 4> GEPIndices;
3212 
3213  /// The base pointer of the original op, used as a base for GEPing the
3214  /// split operations.
3215  Value *Ptr;
3216 
3217  /// The base pointee type being GEPed into.
3218  Type *BaseTy;
3219 
3220  /// Known alignment of the base pointer.
3221  unsigned BaseAlign;
3222 
3223  /// To calculate offset of each component so we can correctly deduce
3224  /// alignments.
3225  const DataLayout &DL;
3226 
3227  /// Initialize the splitter with an insertion point, Ptr and start with a
3228  /// single zero GEP index.
3229  OpSplitter(Instruction *InsertionPoint, Value *Ptr, Type *BaseTy,
3230  unsigned BaseAlign, const DataLayout &DL)
3231  : IRB(InsertionPoint), GEPIndices(1, IRB.getInt32(0)), Ptr(Ptr),
3232  BaseTy(BaseTy), BaseAlign(BaseAlign), DL(DL) {}
3233 
3234  public:
3235  /// Generic recursive split emission routine.
3236  ///
3237  /// This method recursively splits an aggregate op (load or store) into
3238  /// scalar or vector ops. It splits recursively until it hits a single value
3239  /// and emits that single value operation via the template argument.
3240  ///
3241  /// The logic of this routine relies on GEPs and insertvalue and
3242  /// extractvalue all operating with the same fundamental index list, merely
3243  /// formatted differently (GEPs need actual values).
3244  ///
3245  /// \param Ty The type being split recursively into smaller ops.
3246  /// \param Agg The aggregate value being built up or stored, depending on
3247  /// whether this is splitting a load or a store respectively.
3248  void emitSplitOps(Type *Ty, Value *&Agg, const Twine &Name) {
3249  if (Ty->isSingleValueType()) {
3250  unsigned Offset = DL.getIndexedOffsetInType(BaseTy, GEPIndices);
3251  return static_cast<Derived *>(this)->emitFunc(
3252  Ty, Agg, MinAlign(BaseAlign, Offset), Name);
3253  }
3254 
3255  if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
3256  unsigned OldSize = Indices.size();
3257  (void)OldSize;
3258  for (unsigned Idx = 0, Size = ATy->getNumElements(); Idx != Size;
3259  ++Idx) {
3260  assert(Indices.size() == OldSize && "Did not return to the old size");
3261  Indices.push_back(Idx);
3262  GEPIndices.push_back(IRB.getInt32(Idx));
3263  emitSplitOps(ATy->getElementType(), Agg, Name + "." + Twine(Idx));
3264  GEPIndices.pop_back();
3265  Indices.pop_back();
3266  }
3267  return;
3268  }
3269 
3270  if (StructType *STy = dyn_cast<StructType>(Ty)) {
3271  unsigned OldSize = Indices.size();
3272  (void)OldSize;
3273  for (unsigned Idx = 0, Size = STy->getNumElements(); Idx != Size;
3274  ++Idx) {
3275  assert(Indices.size() == OldSize && "Did not return to the old size");
3276  Indices.push_back(Idx);
3277  GEPIndices.push_back(IRB.getInt32(Idx));
3278  emitSplitOps(STy->getElementType(Idx), Agg, Name + "." + Twine(Idx));
3279  GEPIndices.pop_back();
3280  Indices.pop_back();
3281  }
3282  return;
3283  }
3284 
3285  llvm_unreachable("Only arrays and structs are aggregate loadable types");
3286  }
3287  };
3288 
3289  struct LoadOpSplitter : public OpSplitter<LoadOpSplitter> {
3290  AAMDNodes AATags;
3291 
3292  LoadOpSplitter(Instruction *InsertionPoint, Value *Ptr, Type *BaseTy,
3293  AAMDNodes AATags, unsigned BaseAlign, const DataLayout &DL)
3294  : OpSplitter<LoadOpSplitter>(InsertionPoint, Ptr, BaseTy, BaseAlign,
3295  DL), AATags(AATags) {}
3296 
3297  /// Emit a leaf load of a single value. This is called at the leaves of the
3298  /// recursive emission to actually load values.
3299  void emitFunc(Type *Ty, Value *&Agg, unsigned Align, const Twine &Name) {
3300  assert(Ty->isSingleValueType());
3301  // Load the single value and insert it using the indices.
3302  Value *GEP =
3303  IRB.CreateInBoundsGEP(nullptr, Ptr, GEPIndices, Name + ".gep");
3304  LoadInst *Load = IRB.CreateAlignedLoad(GEP, Align, Name + ".load");
3305  if (AATags)
3306  Load->setAAMetadata(AATags);
3307  Agg = IRB.CreateInsertValue(Agg, Load, Indices, Name + ".insert");
3308  LLVM_DEBUG(dbgs() << " to: " << *Load << "\n");
3309  }
3310  };
3311 
3312  bool visitLoadInst(LoadInst &LI) {
3313  assert(LI.getPointerOperand() == *U);
3314  if (!LI.isSimple() || LI.getType()->isSingleValueType())
3315  return false;
3316 
3317  // We have an aggregate being loaded, split it apart.
3318  LLVM_DEBUG(dbgs() << " original: " << LI << "\n");
3319  AAMDNodes AATags;
3320  LI.getAAMetadata(AATags);
3321  LoadOpSplitter Splitter(&LI, *U, LI.getType(), AATags,
3322  getAdjustedAlignment(&LI, 0, DL), DL);
3323  Value *V = UndefValue::get(LI.getType());
3324  Splitter.emitSplitOps(LI.getType(), V, LI.getName() + ".fca");
3325  LI.replaceAllUsesWith(V);
3326  LI.eraseFromParent();
3327  return true;
3328  }
3329 
3330  struct StoreOpSplitter : public OpSplitter<StoreOpSplitter> {
3331  StoreOpSplitter(Instruction *InsertionPoint, Value *Ptr, Type *BaseTy,
3332  AAMDNodes AATags, unsigned BaseAlign, const DataLayout &DL)
3333  : OpSplitter<StoreOpSplitter>(InsertionPoint, Ptr, BaseTy, BaseAlign,
3334  DL),
3335  AATags(AATags) {}
3336  AAMDNodes AATags;
3337  /// Emit a leaf store of a single value. This is called at the leaves of the
3338  /// recursive emission to actually produce stores.
3339  void emitFunc(Type *Ty, Value *&Agg, unsigned Align, const Twine &Name) {
3340  assert(Ty->isSingleValueType());
3341  // Extract the single value and store it using the indices.
3342  //
3343  // The gep and extractvalue values are factored out of the CreateStore
3344  // call to make the output independent of the argument evaluation order.
3345  Value *ExtractValue =
3346  IRB.CreateExtractValue(Agg, Indices, Name + ".extract");
3347  Value *InBoundsGEP =
3348  IRB.CreateInBoundsGEP(nullptr, Ptr, GEPIndices, Name + ".gep");
3349  StoreInst *Store =
3350  IRB.CreateAlignedStore(ExtractValue, InBoundsGEP, Align);
3351  if (AATags)
3352  Store->setAAMetadata(AATags);
3353  LLVM_DEBUG(dbgs() << " to: " << *Store << "\n");
3354  }
3355  };
3356 
3357  bool visitStoreInst(StoreInst &SI) {
3358  if (!SI.isSimple() || SI.getPointerOperand() != *U)
3359  return false;
3360  Value *V = SI.getValueOperand();
3361  if (V->getType()->isSingleValueType())
3362  return false;
3363 
3364  // We have an aggregate being stored, split it apart.
3365  LLVM_DEBUG(dbgs() << " original: " << SI << "\n");
3366  AAMDNodes AATags;
3367  SI.getAAMetadata(AATags);
3368  StoreOpSplitter Splitter(&SI, *U, V->getType(), AATags,
3369  getAdjustedAlignment(&SI, 0, DL), DL);
3370  Splitter.emitSplitOps(V->getType(), V, V->getName() + ".fca");
3371  SI.eraseFromParent();
3372  return true;
3373  }
3374 
3375  bool visitBitCastInst(BitCastInst &BC) {
3376  enqueueUsers(BC);
3377  return false;
3378  }
3379 
3380  bool visitGetElementPtrInst(GetElementPtrInst &GEPI) {
3381  enqueueUsers(GEPI);
3382  return false;
3383  }
3384 
3385  bool visitPHINode(PHINode &PN) {
3386  enqueueUsers(PN);
3387  return false;
3388  }
3389 
3390  bool visitSelectInst(SelectInst &SI) {
3391  enqueueUsers(SI);
3392  return false;
3393  }
3394 };
3395 
3396 } // end anonymous namespace
3397 
3398 /// Strip aggregate type wrapping.
3399 ///
3400 /// This removes no-op aggregate types wrapping an underlying type. It will
3401 /// strip as many layers of types as it can without changing either the type
3402 /// size or the allocated size.
3404  if (Ty->isSingleValueType())
3405  return Ty;
3406 
3407  uint64_t AllocSize = DL.getTypeAllocSize(Ty);
3408  uint64_t TypeSize = DL.getTypeSizeInBits(Ty);
3409 
3410  Type *InnerTy;
3411  if (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty)) {
3412  InnerTy = ArrTy->getElementType();
3413  } else if (StructType *STy = dyn_cast<StructType>(Ty)) {
3414  const StructLayout *SL = DL.getStructLayout(STy);
3415  unsigned Index = SL->getElementContainingOffset(0);
3416  InnerTy = STy->getElementType(Index);
3417  } else {
3418  return Ty;
3419  }
3420 
3421  if (AllocSize > DL.getTypeAllocSize(InnerTy) ||
3422  TypeSize > DL.getTypeSizeInBits(InnerTy))
3423  return Ty;
3424 
3425  return stripAggregateTypeWrapping(DL, InnerTy);
3426 }
3427 
3428 /// Try to find a partition of the aggregate type passed in for a given
3429 /// offset and size.
3430 ///
3431 /// This recurses through the aggregate type and tries to compute a subtype
3432 /// based on the offset and size. When the offset and size span a sub-section
3433 /// of an array, it will even compute a new array type for that sub-section,
3434 /// and the same for structs.
3435 ///
3436 /// Note that this routine is very strict and tries to find a partition of the
3437 /// type which produces the *exact* right offset and size. It is not forgiving
3438 /// when the size or offset cause either end of type-based partition to be off.
3439 /// Also, this is a best-effort routine. It is reasonable to give up and not
3440 /// return a type if necessary.
3441 static Type *getTypePartition(const DataLayout &DL, Type *Ty, uint64_t Offset,
3442  uint64_t Size) {
3443  if (Offset == 0 && DL.getTypeAllocSize(Ty) == Size)
3444  return stripAggregateTypeWrapping(DL, Ty);
3445  if (Offset > DL.getTypeAllocSize(Ty) ||
3446  (DL.getTypeAllocSize(Ty) - Offset) < Size)
3447  return nullptr;
3448 
3449  if (SequentialType *SeqTy = dyn_cast<SequentialType>(Ty)) {
3450  Type *ElementTy = SeqTy->getElementType();
3451  uint64_t ElementSize = DL.getTypeAllocSize(ElementTy);
3452  uint64_t NumSkippedElements = Offset / ElementSize;
3453  if (NumSkippedElements >= SeqTy->getNumElements())
3454  return nullptr;
3455  Offset -= NumSkippedElements * ElementSize;
3456 
3457  // First check if we need to recurse.
3458  if (Offset > 0 || Size < ElementSize) {
3459  // Bail if the partition ends in a different array element.
3460  if ((Offset + Size) > ElementSize)
3461  return nullptr;
3462  // Recurse through the element type trying to peel off offset bytes.
3463  return getTypePartition(DL, ElementTy, Offset, Size);
3464  }
3465  assert(Offset == 0);
3466 
3467  if (Size == ElementSize)
3468  return stripAggregateTypeWrapping(DL, ElementTy);
3469  assert(Size > ElementSize);
3470  uint64_t NumElements = Size / ElementSize;
3471  if (NumElements * ElementSize != Size)
3472  return nullptr;
3473  return ArrayType::get(ElementTy, NumElements);
3474  }
3475 
3476  StructType *STy = dyn_cast<StructType>(Ty);
3477  if (!STy)
3478  return nullptr;
3479 
3480  const StructLayout *SL = DL.getStructLayout(STy);
3481  if (Offset >= SL->getSizeInBytes())
3482  return nullptr;
3483  uint64_t EndOffset = Offset + Size;
3484  if (EndOffset > SL->getSizeInBytes())
3485  return nullptr;
3486 
3487  unsigned Index = SL->getElementContainingOffset(Offset);
3488  Offset -= SL->getElementOffset(Index);
3489 
3490  Type *ElementTy = STy->getElementType(Index);
3491  uint64_t ElementSize = DL.getTypeAllocSize(ElementTy);
3492  if (Offset >= ElementSize)
3493  return nullptr; // The offset points into alignment padding.
3494 
3495  // See if any partition must be contained by the element.
3496  if (Offset > 0 || Size < ElementSize) {
3497  if ((Offset + Size) > ElementSize)
3498  return nullptr;
3499  return getTypePartition(DL, ElementTy, Offset, Size);
3500  }
3501  assert(Offset == 0);
3502 
3503  if (Size == ElementSize)
3504  return stripAggregateTypeWrapping(DL, ElementTy);
3505 
3507  EE = STy->element_end();
3508  if (EndOffset < SL->getSizeInBytes()) {
3509  unsigned EndIndex = SL->getElementContainingOffset(EndOffset);
3510  if (Index == EndIndex)
3511  return nullptr; // Within a single element and its padding.
3512 
3513  // Don't try to form "natural" types if the elements don't line up with the
3514  // expected size.
3515  // FIXME: We could potentially recurse down through the last element in the
3516  // sub-struct to find a natural end point.
3517  if (SL->getElementOffset(EndIndex) != EndOffset)
3518  return nullptr;
3519 
3520  assert(Index < EndIndex);
3521  EE = STy->element_begin() + EndIndex;
3522  }
3523 
3524  // Try to build up a sub-structure.
3525  StructType *SubTy =
3526  StructType::get(STy->getContext(), makeArrayRef(EI, EE), STy->isPacked());
3527  const StructLayout *SubSL = DL.getStructLayout(SubTy);
3528  if (Size != SubSL->getSizeInBytes())
3529  return nullptr; // The sub-struct doesn't have quite the size needed.
3530 
3531  return SubTy;
3532 }
3533 
3534 /// Pre-split loads and stores to simplify rewriting.
3535 ///
3536 /// We want to break up the splittable load+store pairs as much as
3537 /// possible. This is important to do as a preprocessing step, as once we
3538 /// start rewriting the accesses to partitions of the alloca we lose the
3539 /// necessary information to correctly split apart paired loads and stores
3540 /// which both point into this alloca. The case to consider is something like
3541 /// the following:
3542 ///
3543 /// %a = alloca [12 x i8]
3544 /// %gep1 = getelementptr [12 x i8]* %a, i32 0, i32 0
3545 /// %gep2 = getelementptr [12 x i8]* %a, i32 0, i32 4
3546 /// %gep3 = getelementptr [12 x i8]* %a, i32 0, i32 8
3547 /// %iptr1 = bitcast i8* %gep1 to i64*
3548 /// %iptr2 = bitcast i8* %gep2 to i64*
3549 /// %fptr1 = bitcast i8* %gep1 to float*
3550 /// %fptr2 = bitcast i8* %gep2 to float*
3551 /// %fptr3 = bitcast i8* %gep3 to float*
3552 /// store float 0.0, float* %fptr1
3553 /// store float 1.0, float* %fptr2
3554 /// %v = load i64* %iptr1
3555 /// store i64 %v, i64* %iptr2
3556 /// %f1 = load float* %fptr2
3557 /// %f2 = load float* %fptr3
3558 ///
3559 /// Here we want to form 3 partitions of the alloca, each 4 bytes large, and
3560 /// promote everything so we recover the 2 SSA values that should have been
3561 /// there all along.
3562 ///
3563 /// \returns true if any changes are made.
3564 bool SROA::presplitLoadsAndStores(AllocaInst &AI, AllocaSlices &AS) {
3565  LLVM_DEBUG(dbgs() << "Pre-splitting loads and stores\n");
3566 
3567  // Track the loads and stores which are candidates for pre-splitting here, in
3568  // the order they first appear during the partition scan. These give stable
3569  // iteration order and a basis for tracking which loads and stores we
3570  // actually split.
3573 
3574  // We need to accumulate the splits required of each load or store where we
3575  // can find them via a direct lookup. This is important to cross-check loads
3576  // and stores against each other. We also track the slice so that we can kill
3577  // all the slices that end up split.
3578  struct SplitOffsets {
3579  Slice *S;
3580  std::vector<uint64_t> Splits;
3581  };
3583 
3584  // Track loads out of this alloca which cannot, for any reason, be pre-split.
3585  // This is important as we also cannot pre-split stores of those loads!
3586  // FIXME: This is all pretty gross. It means that we can be more aggressive
3587  // in pre-splitting when the load feeding the store happens to come from
3588  // a separate alloca. Put another way, the effectiveness of SROA would be
3589  // decreased by a frontend which just concatenated all of its local allocas
3590  // into one big flat alloca. But defeating such patterns is exactly the job
3591  // SROA is tasked with! Sadly, to not have this discrepancy we would have
3592  // change store pre-splitting to actually force pre-splitting of the load
3593  // that feeds it *and all stores*. That makes pre-splitting much harder, but
3594  // maybe it would make it more principled?
3595  SmallPtrSet<LoadInst *, 8> UnsplittableLoads;
3596 
3597  LLVM_DEBUG(dbgs() << " Searching for candidate loads and stores\n");
3598  for (auto &P : AS.partitions()) {
3599  for (Slice &S : P) {
3600  Instruction *I = cast<Instruction>(S.getUse()->getUser());
3601  if (!S.isSplittable() || S.endOffset() <= P.endOffset()) {
3602  // If this is a load we have to track that it can't participate in any
3603  // pre-splitting. If this is a store of a load we have to track that
3604  // that load also can't participate in any pre-splitting.
3605  if (auto *LI = dyn_cast<LoadInst>(I))
3606  UnsplittableLoads.insert(LI);
3607  else if (auto *SI = dyn_cast<StoreInst>(I))
3608  if (auto *LI = dyn_cast<LoadInst>(SI->getValueOperand()))
3609  UnsplittableLoads.insert(LI);
3610  continue;
3611  }
3612  assert(P.endOffset() > S.beginOffset() &&
3613  "Empty or backwards partition!");
3614 
3615  // Determine if this is a pre-splittable slice.
3616  if (auto *LI = dyn_cast<LoadInst>(I)) {
3617  assert(!LI->isVolatile() && "Cannot split volatile loads!");
3618 
3619  // The load must be used exclusively to store into other pointers for
3620  // us to be able to arbitrarily pre-split it. The stores must also be
3621  // simple to avoid changing semantics.
3622  auto IsLoadSimplyStored = [](LoadInst *LI) {
3623  for (User *LU : LI->users()) {
3624  auto *SI = dyn_cast<StoreInst>(LU);
3625  if (!SI || !SI->isSimple())
3626  return false;
3627  }
3628  return true;
3629  };
3630  if (!IsLoadSimplyStored(LI)) {
3631  UnsplittableLoads.insert(LI);
3632  continue;
3633  }
3634 
3635  Loads.push_back(LI);
3636  } else if (auto *SI = dyn_cast<StoreInst>(I)) {
3637  if (S.getUse() != &SI->getOperandUse(SI->getPointerOperandIndex()))
3638  // Skip stores *of* pointers. FIXME: This shouldn't even be possible!
3639  continue;
3640  auto *StoredLoad = dyn_cast<LoadInst>(SI->getValueOperand());
3641  if (!StoredLoad || !StoredLoad->isSimple())
3642  continue;
3643  assert(!SI->isVolatile() && "Cannot split volatile stores!");
3644 
3645  Stores.push_back(SI);
3646  } else {
3647  // Other uses cannot be pre-split.
3648  continue;
3649  }
3650 
3651  // Record the initial split.
3652  LLVM_DEBUG(dbgs() << " Candidate: " << *I << "\n");
3653  auto &Offsets = SplitOffsetsMap[I];
3654  assert(Offsets.Splits.empty() &&
3655  "Should not have splits the first time we see an instruction!");
3656  Offsets.S = &S;
3657  Offsets.Splits.push_back(P.endOffset() - S.beginOffset());
3658  }
3659 
3660  // Now scan the already split slices, and add a split for any of them which
3661  // we're going to pre-split.
3662  for (Slice *S : P.splitSliceTails()) {
3663  auto SplitOffsetsMapI =
3664  SplitOffsetsMap.find(cast<Instruction>(S->getUse()->getUser()));
3665  if (SplitOffsetsMapI == SplitOffsetsMap.end())
3666  continue;
3667  auto &Offsets = SplitOffsetsMapI->second;
3668 
3669  assert(Offsets.S == S && "Found a mismatched slice!");
3670  assert(!Offsets.Splits.empty() &&
3671  "Cannot have an empty set of splits on the second partition!");
3672  assert(Offsets.Splits.back() ==
3673  P.beginOffset() - Offsets.S->beginOffset() &&
3674  "Previous split does not end where this one begins!");
3675 
3676  // Record each split. The last partition's end isn't needed as the size
3677  // of the slice dictates that.
3678  if (S->endOffset() > P.endOffset())
3679  Offsets.Splits.push_back(P.endOffset() - Offsets.S->beginOffset());
3680  }
3681  }
3682 
3683  // We may have split loads where some of their stores are split stores. For
3684  // such loads and stores, we can only pre-split them if their splits exactly
3685  // match relative to their starting offset. We have to verify this prior to
3686  // any rewriting.
3687  Stores.erase(
3688  llvm::remove_if(Stores,
3689  [&UnsplittableLoads, &SplitOffsetsMap](StoreInst *SI) {
3690  // Lookup the load we are storing in our map of split
3691  // offsets.
3692  auto *LI = cast<LoadInst>(SI->getValueOperand());
3693  // If it was completely unsplittable, then we're done,
3694  // and this store can't be pre-split.
3695  if (UnsplittableLoads.count(LI))
3696  return true;
3697 
3698  auto LoadOffsetsI = SplitOffsetsMap.find(LI);
3699  if (LoadOffsetsI == SplitOffsetsMap.end())
3700  return false; // Unrelated loads are definitely safe.
3701  auto &LoadOffsets = LoadOffsetsI->second;
3702 
3703  // Now lookup the store's offsets.
3704  auto &StoreOffsets = SplitOffsetsMap[SI];
3705 
3706  // If the relative offsets of each split in the load and
3707  // store match exactly, then we can split them and we
3708  // don't need to remove them here.
3709  if (LoadOffsets.Splits == StoreOffsets.Splits)
3710  return false;
3711 
3712  LLVM_DEBUG(
3713  dbgs()
3714  << " Mismatched splits for load and store:\n"
3715  << " " << *LI << "\n"
3716  << " " << *SI << "\n");
3717 
3718  // We've found a store and load that we need to split
3719  // with mismatched relative splits. Just give up on them
3720  // and remove both instructions from our list of
3721  // candidates.
3722  UnsplittableLoads.insert(LI);
3723  return true;
3724  }),
3725  Stores.end());
3726  // Now we have to go *back* through all the stores, because a later store may
3727  // have caused an earlier store's load to become unsplittable and if it is
3728  // unsplittable for the later store, then we can't rely on it being split in
3729  // the earlier store either.
3730  Stores.erase(llvm::remove_if(Stores,
3731  [&UnsplittableLoads](StoreInst *SI) {
3732  auto *LI =
3733  cast<LoadInst>(SI->getValueOperand());
3734  return UnsplittableLoads.count(LI);
3735  }),
3736  Stores.end());
3737  // Once we've established all the loads that can't be split for some reason,
3738  // filter any that made it into our list out.
3739  Loads.erase(llvm::remove_if(Loads,
3740  [&UnsplittableLoads](LoadInst *LI) {
3741  return UnsplittableLoads.count(LI);
3742  }),
3743  Loads.end());
3744 
3745  // If no loads or stores are left, there is no pre-splitting to be done for
3746  // this alloca.
3747  if (Loads.empty() && Stores.empty())
3748  return false;
3749 
3750  // From here on, we can't fail and will be building new accesses, so rig up
3751  // an IR builder.
3752  IRBuilderTy IRB(&AI);
3753 
3754  // Collect the new slices which we will merge into the alloca slices.
3755  SmallVector<Slice, 4> NewSlices;
3756 
3757  // Track any allocas we end up splitting loads and stores for so we iterate
3758  // on them.
3759  SmallPtrSet<AllocaInst *, 4> ResplitPromotableAllocas;
3760 
3761  // At this point, we have collected all of the loads and stores we can
3762  // pre-split, and the specific splits needed for them. We actually do the
3763  // splitting in a specific order in order to handle when one of the loads in
3764  // the value operand to one of the stores.
3765  //
3766  // First, we rewrite all of the split loads, and just accumulate each split
3767  // load in a parallel structure. We also build the slices for them and append
3768  // them to the alloca slices.
3770  std::vector<LoadInst *> SplitLoads;
3771  const DataLayout &DL = AI.getModule()->getDataLayout();
3772  for (LoadInst *LI : Loads) {
3773  SplitLoads.clear();
3774 
3775  IntegerType *Ty = cast<IntegerType>(LI->getType());
3776  uint64_t LoadSize = Ty->getBitWidth() / 8;
3777  assert(LoadSize > 0 && "Cannot have a zero-sized integer load!");
3778 
3779  auto &Offsets = SplitOffsetsMap[LI];
3780  assert(LoadSize == Offsets.S->endOffset() - Offsets.S->beginOffset() &&
3781  "Slice size should always match load size exactly!");
3782  uint64_t BaseOffset = Offsets.S->beginOffset();
3783  assert(BaseOffset + LoadSize > BaseOffset &&
3784  "Cannot represent alloca access size using 64-bit integers!");
3785 
3786  Instruction *BasePtr = cast<Instruction>(LI->getPointerOperand());
3787  IRB.SetInsertPoint(LI);
3788 
3789  LLVM_DEBUG(dbgs() << " Splitting load: " << *LI << "\n");
3790 
3791  uint64_t PartOffset = 0, PartSize = Offsets.Splits.front();
3792  int Idx = 0, Size = Offsets.Splits.size();
3793  for (;;) {
3794  auto *PartTy = Type::getIntNTy(Ty->getContext(), PartSize * 8);
3795  auto AS = LI->getPointerAddressSpace();
3796  auto *PartPtrTy = PartTy->getPointerTo(AS);
3797  LoadInst *PLoad = IRB.CreateAlignedLoad(
3798  getAdjustedPtr(IRB, DL, BasePtr,
3799  APInt(DL.getIndexSizeInBits(AS), PartOffset),
3800  PartPtrTy, BasePtr->getName() + "."),
3801  getAdjustedAlignment(LI, PartOffset, DL), /*IsVolatile*/ false,
3802  LI->getName());
3805 
3806  // Append this load onto the list of split loads so we can find it later
3807  // to rewrite the stores.
3808  SplitLoads.push_back(PLoad);
3809 
3810  // Now build a new slice for the alloca.
3811  NewSlices.push_back(
3812  Slice(BaseOffset + PartOffset, BaseOffset + PartOffset + PartSize,
3813  &PLoad->getOperandUse(PLoad->getPointerOperandIndex()),
3814  /*IsSplittable*/ false));
3815  LLVM_DEBUG(dbgs() << " new slice [" << NewSlices.back().beginOffset()
3816  << ", " << NewSlices.back().endOffset()
3817  << "): " << *PLoad << "\n");
3818 
3819  // See if we've handled all the splits.
3820  if (Idx >= Size)
3821  break;
3822 
3823  // Setup the next partition.
3824  PartOffset = Offsets.Splits[Idx];
3825  ++Idx;
3826  PartSize = (Idx < Size ? Offsets.Splits[Idx] : LoadSize) - PartOffset;
3827  }
3828 
3829  // Now that we have the split loads, do the slow walk over all uses of the
3830  // load and rewrite them as split stores, or save the split loads to use
3831  // below if the store is going to be split there anyways.
3832  bool DeferredStores = false;
3833  for (User *LU : LI->users()) {
3834  StoreInst *SI = cast<StoreInst>(LU);
3835  if (!Stores.empty() && SplitOffsetsMap.count(SI)) {
3836  DeferredStores = true;
3837  LLVM_DEBUG(dbgs() << " Deferred splitting of store: " << *SI
3838  << "\n");
3839  continue;
3840  }
3841 
3842  Value *StoreBasePtr = SI->getPointerOperand();
3843  IRB.SetInsertPoint(SI);
3844 
3845  LLVM_DEBUG(dbgs() << " Splitting store of load: " << *SI << "\n");
3846 
3847  for (int Idx = 0, Size = SplitLoads.size(); Idx < Size; ++Idx) {
3848  LoadInst *PLoad = SplitLoads[Idx];
3849  uint64_t PartOffset = Idx == 0 ? 0 : Offsets.Splits[Idx - 1];
3850  auto *PartPtrTy =
3851  PLoad->getType()->getPointerTo(SI->getPointerAddressSpace());
3852 
3853  auto AS = SI->getPointerAddressSpace();
3854  StoreInst *PStore = IRB.CreateAlignedStore(
3855  PLoad,
3856  getAdjustedPtr(IRB, DL, StoreBasePtr,
3857  APInt(DL.getIndexSizeInBits(AS), PartOffset),
3858  PartPtrTy, StoreBasePtr->getName() + "."),
3859  getAdjustedAlignment(SI, PartOffset, DL), /*IsVolatile*/ false);
3862  LLVM_DEBUG(dbgs() << " +" << PartOffset << ":" << *PStore << "\n");
3863  }
3864 
3865  // We want to immediately iterate on any allocas impacted by splitting
3866  // this store, and we have to track any promotable alloca (indicated by
3867  // a direct store) as needing to be resplit because it is no longer
3868  // promotable.
3869  if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(StoreBasePtr)) {
3870  ResplitPromotableAllocas.insert(OtherAI);
3871  Worklist.insert(OtherAI);
3872  } else if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(
3873  StoreBasePtr->stripInBoundsOffsets())) {
3874  Worklist.insert(OtherAI);
3875  }
3876 
3877  // Mark the original store as dead.
3878  DeadInsts.insert(SI);
3879  }
3880 
3881  // Save the split loads if there are deferred stores among the users.
3882  if (DeferredStores)
3883  SplitLoadsMap.insert(std::make_pair(LI, std::move(SplitLoads)));
3884 
3885  // Mark the original load as dead and kill the original slice.
3886  DeadInsts.insert(LI);
3887  Offsets.S->kill();
3888  }
3889 
3890  // Second, we rewrite all of the split stores. At this point, we know that
3891  // all loads from this alloca have been split already. For stores of such
3892  // loads, we can simply look up the pre-existing split loads. For stores of
3893  // other loads, we split those loads first and then write split stores of
3894  // them.
3895  for (StoreInst *SI : Stores) {
3896  auto *LI = cast<LoadInst>(SI->getValueOperand());
3897  IntegerType *Ty = cast<IntegerType>(LI->getType());
3898  uint64_t StoreSize = Ty->getBitWidth() / 8;
3899  assert(StoreSize > 0 && "Cannot have a zero-sized integer store!");
3900 
3901  auto &Offsets = SplitOffsetsMap[SI];
3902  assert(StoreSize == Offsets.S->endOffset() - Offsets.S->beginOffset() &&
3903  "Slice size should always match load size exactly!");
3904  uint64_t BaseOffset = Offsets.S->beginOffset();
3905  assert(BaseOffset + StoreSize > BaseOffset &&
3906  "Cannot represent alloca access size using 64-bit integers!");
3907 
3908  Value *LoadBasePtr = LI->getPointerOperand();
3909  Instruction *StoreBasePtr = cast<Instruction>(SI->getPointerOperand());
3910 
3911  LLVM_DEBUG(dbgs() << " Splitting store: " << *SI << "\n");
3912 
3913  // Check whether we have an already split load.
3914  auto SplitLoadsMapI = SplitLoadsMap.find(LI);
3915  std::vector<LoadInst *> *SplitLoads = nullptr;
3916  if (SplitLoadsMapI != SplitLoadsMap.end()) {
3917  SplitLoads = &SplitLoadsMapI->second;
3918  assert(SplitLoads->size() == Offsets.Splits.size() + 1 &&
3919  "Too few split loads for the number of splits in the store!");
3920  } else {
3921  LLVM_DEBUG(dbgs() << " of load: " << *LI << "\n");
3922  }
3923 
3924  uint64_t PartOffset = 0, PartSize = Offsets.Splits.front();
3925  int Idx = 0, Size = Offsets.Splits.size();
3926  for (;;) {
3927  auto *PartTy = Type::getIntNTy(Ty->getContext(), PartSize * 8);
3928  auto *LoadPartPtrTy = PartTy->getPointerTo(LI->getPointerAddressSpace());
3929  auto *StorePartPtrTy = PartTy->getPointerTo(SI->getPointerAddressSpace());
3930 
3931  // Either lookup a split load or create one.
3932  LoadInst *PLoad;
3933  if (SplitLoads) {
3934  PLoad = (*SplitLoads)[Idx];
3935  } else {
3936  IRB.SetInsertPoint(LI);
3937  auto AS = LI->getPointerAddressSpace();
3938  PLoad = IRB.CreateAlignedLoad(
3939  getAdjustedPtr(IRB, DL, LoadBasePtr,
3940  APInt(DL.getIndexSizeInBits(AS), PartOffset),
3941  LoadPartPtrTy, LoadBasePtr->getName() + "."),
3942  getAdjustedAlignment(LI, PartOffset, DL), /*IsVolatile*/ false,
3943  LI->getName());
3944  }
3945 
3946  // And store this partition.
3947  IRB.SetInsertPoint(SI);
3948  auto AS = SI->getPointerAddressSpace();
3949  StoreInst *PStore = IRB.CreateAlignedStore(
3950  PLoad,
3951  getAdjustedPtr(IRB, DL, StoreBasePtr,
3952  APInt(DL.getIndexSizeInBits(AS), PartOffset),
3953  StorePartPtrTy, StoreBasePtr->getName() + "."),
3954  getAdjustedAlignment(SI, PartOffset, DL), /*IsVolatile*/ false);
3955 
3956  // Now build a new slice for the alloca.
3957  NewSlices.push_back(
3958  Slice(BaseOffset + PartOffset, BaseOffset + PartOffset + PartSize,
3959  &PStore->getOperandUse(PStore->getPointerOperandIndex()),
3960  /*IsSplittable*/ false));
3961  LLVM_DEBUG(dbgs() << " new slice [" << NewSlices.back().beginOffset()
3962  << ", " << NewSlices.back().endOffset()
3963  << "): " << *PStore << "\n");
3964  if (!SplitLoads) {
3965  LLVM_DEBUG(dbgs() << " of split load: " << *PLoad << "\n");
3966  }
3967 
3968  // See if we've finished all the splits.
3969  if (Idx >= Size)
3970  break;
3971 
3972  // Setup the next partition.
3973  PartOffset = Offsets.Splits[Idx];
3974  ++Idx;
3975  PartSize = (Idx < Size ? Offsets.Splits[Idx] : StoreSize) - PartOffset;
3976  }
3977 
3978  // We want to immediately iterate on any allocas impacted by splitting
3979  // this load, which is only relevant if it isn't a load of this alloca and
3980  // thus we didn't already split the loads above. We also have to keep track
3981  // of any promotable allocas we split loads on as they can no longer be
3982  // promoted.
3983  if (!SplitLoads) {
3984  if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(LoadBasePtr)) {
3985  assert(OtherAI != &AI && "We can't re-split our own alloca!");
3986  ResplitPromotableAllocas.insert(OtherAI);
3987  Worklist.insert(OtherAI);
3988  } else if (AllocaInst *OtherAI = dyn_cast<AllocaInst>(
3989  LoadBasePtr->stripInBoundsOffsets())) {
3990  assert(OtherAI != &AI && "We can't re-split our own alloca!");
3991  Worklist.insert(OtherAI);
3992  }
3993  }
3994 
3995  // Mark the original store as dead now that we've split it up and kill its
3996  // slice. Note that we leave the original load in place unless this store
3997  // was its only use. It may in turn be split up if it is an alloca load
3998  // for some other alloca, but it may be a normal load. This may introduce
3999  // redundant loads, but where those can be merged the rest of the optimizer
4000  // should handle the merging, and this uncovers SSA splits which is more
4001  // important. In practice, the original loads will almost always be fully
4002  // split and removed eventually, and the splits will be merged by any
4003  // trivial CSE, including instcombine.
4004  if (LI->hasOneUse()) {
4005  assert(*LI->user_begin() == SI && "Single use isn't this store!");
4006  DeadInsts.insert(LI);
4007  }
4008  DeadInsts.insert(SI);
4009  Offsets.S->kill();
4010  }
4011 
4012  // Remove the killed slices that have ben pre-split.
4013  AS.erase(llvm::remove_if(AS, [](const Slice &S) { return S.isDead(); }),
4014  AS.end());
4015 
4016  // Insert our new slices. This will sort and merge them into the sorted
4017  // sequence.
4018  AS.insert(NewSlices);
4019 
4020  LLVM_DEBUG(dbgs() << " Pre-split slices:\n");
4021 #ifndef NDEBUG
4022  for (auto I = AS.begin(), E = AS.end(); I != E; ++I)
4023  LLVM_DEBUG(AS.print(dbgs(), I, " "));
4024 #endif
4025 
4026  // Finally, don't try to promote any allocas that new require re-splitting.
4027  // They have already been added to the worklist above.
4028  PromotableAllocas.erase(
4030  PromotableAllocas,
4031  [&](AllocaInst *AI) { return ResplitPromotableAllocas.count(AI); }),
4032  PromotableAllocas.end());
4033 
4034  return true;
4035 }
4036 
4037 /// Rewrite an alloca partition's users.
4038 ///
4039 /// This routine drives both of the rewriting goals of the SROA pass. It tries
4040 /// to rewrite uses of an alloca partition to be conducive for SSA value
4041 /// promotion. If the partition needs a new, more refined alloca, this will
4042 /// build that new alloca, preserving as much type information as possible, and
4043 /// rewrite the uses of the old alloca to point at the new one and have the
4044 /// appropriate new offsets. It also evaluates how successful the rewrite was
4045 /// at enabling promotion and if it was successful queues the alloca to be
4046 /// promoted.
4047 AllocaInst *SROA::rewritePartition(AllocaInst &AI, AllocaSlices &AS,
4048  Partition &P) {
4049  // Try to compute a friendly type for this partition of the alloca. This
4050  // won't always succeed, in which case we fall back to a legal integer type
4051  // or an i8 array of an appropriate size.
4052  Type *SliceTy = nullptr;
4053  const DataLayout &DL = AI.getModule()->getDataLayout();
4054  if (Type *CommonUseTy = findCommonType(P.begin(), P.end(), P.endOffset()))
4055  if (DL.getTypeAllocSize(CommonUseTy) >= P.size())
4056  SliceTy = CommonUseTy;
4057  if (!SliceTy)
4058  if (Type *TypePartitionTy = getTypePartition(DL, AI.getAllocatedType(),
4059  P.beginOffset(), P.size()))
4060  SliceTy = TypePartitionTy;
4061  if ((!SliceTy || (SliceTy->isArrayTy() &&
4062  SliceTy->getArrayElementType()->isIntegerTy())) &&
4063  DL.isLegalInteger(P.size() * 8))
4064  SliceTy = Type::getIntNTy(*C, P.size() * 8);
4065  if (!SliceTy)
4066  SliceTy = ArrayType::get(Type::getInt8Ty(*C), P.size());
4067  assert(DL.getTypeAllocSize(SliceTy) >= P.size());
4068 
4069  bool IsIntegerPromotable = isIntegerWideningViable(P, SliceTy, DL);
4070 
4071  VectorType *VecTy =
4072  IsIntegerPromotable ? nullptr : isVectorPromotionViable(P, DL);
4073  if (VecTy)
4074  SliceTy = VecTy;
4075 
4076  // Check for the case where we're going to rewrite to a new alloca of the
4077  // exact same type as the original, and with the same access offsets. In that
4078  // case, re-use the existing alloca, but still run through the rewriter to
4079  // perform phi and select speculation.
4080  // P.beginOffset() can be non-zero even with the same type in a case with
4081  // out-of-bounds access (e.g. @PR35657 function in SROA/basictest.ll).
4082  AllocaInst *NewAI;
4083  if (SliceTy == AI.getAllocatedType() && P.beginOffset() == 0) {
4084  NewAI = &AI;
4085  // FIXME: We should be able to bail at this point with "nothing changed".
4086  // FIXME: We might want to defer PHI speculation until after here.
4087  // FIXME: return nullptr;
4088  } else {
4089  unsigned Alignment = AI.getAlignment();
4090  if (!Alignment) {
4091  // The minimum alignment which users can rely on when the explicit
4092  // alignment is omitted or zero is that required by the ABI for this
4093  // type.
4094  Alignment = DL.getABITypeAlignment(AI.getAllocatedType());
4095  }
4096  Alignment = MinAlign(Alignment, P.beginOffset());
4097  // If we will get at least this much alignment from the type alone, leave
4098  // the alloca's alignment unconstrained.
4099  if (Alignment <= DL.getABITypeAlignment(SliceTy))
4100  Alignment = 0;
4101  NewAI = new AllocaInst(
4102  SliceTy, AI.getType()->getAddressSpace(), nullptr, Alignment,
4103  AI.getName() + ".sroa." + Twine(P.begin() - AS.begin()), &AI);
4104  // Copy the old AI debug location over to the new one.
4105  NewAI->setDebugLoc(AI.getDebugLoc());
4106  ++NumNewAllocas;
4107  }
4108 
4109  LLVM_DEBUG(dbgs() << "Rewriting alloca partition "
4110  << "[" << P.beginOffset() << "," << P.endOffset()
4111  << ") to: " << *NewAI << "\n");
4112 
4113  // Track the high watermark on the worklist as it is only relevant for
4114  // promoted allocas. We will reset it to this point if the alloca is not in
4115  // fact scheduled for promotion.
4116  unsigned PPWOldSize = PostPromotionWorklist.size();
4117  unsigned NumUses = 0;
4119  SmallSetVector<SelectInst *, 8> SelectUsers;
4120 
4121  AllocaSliceRewriter Rewriter(DL, AS, *this, AI, *NewAI, P.beginOffset(),
4122  P.endOffset(), IsIntegerPromotable, VecTy,
4123  PHIUsers, SelectUsers);
4124  bool Promotable = true;
4125  for (Slice *S : P.splitSliceTails()) {
4126  Promotable &= Rewriter.visit(S);
4127  ++NumUses;
4128  }
4129  for (Slice &S : P) {
4130  Promotable &= Rewriter.visit(&S);
4131  ++NumUses;
4132  }
4133 
4134  NumAllocaPartitionUses += NumUses;
4135  MaxUsesPerAllocaPartition.updateMax(NumUses);
4136 
4137  // Now that we've processed all the slices in the new partition, check if any
4138  // PHIs or Selects would block promotion.
4139  for (PHINode *PHI : PHIUsers)
4140  if (!isSafePHIToSpeculate(*PHI)) {
4141  Promotable = false;
4142  PHIUsers.clear();
4143  SelectUsers.clear();
4144  break;
4145  }
4146 
4147  for (SelectInst *Sel : SelectUsers)
4148  if (!isSafeSelectToSpeculate(*Sel)) {
4149  Promotable = false;
4150  PHIUsers.clear();
4151  SelectUsers.clear();
4152  break;
4153  }
4154 
4155  if (Promotable) {
4156  if (PHIUsers.empty() && SelectUsers.empty()) {
4157  // Promote the alloca.
4158  PromotableAllocas.push_back(NewAI);
4159  } else {
4160  // If we have either PHIs or Selects to speculate, add them to those
4161  // worklists and re-queue the new alloca so that we promote in on the
4162  // next iteration.
4163  for (PHINode *PHIUser : PHIUsers)
4164  SpeculatablePHIs.insert(PHIUser);
4165  for (SelectInst *SelectUser : SelectUsers)
4166  SpeculatableSelects.insert(SelectUser);
4167  Worklist.insert(NewAI);
4168  }
4169  } else {
4170  // Drop any post-promotion work items if promotion didn't happen.
4171  while (PostPromotionWorklist.size() > PPWOldSize)
4172  PostPromotionWorklist.pop_back();
4173 
4174  // We couldn't promote and we didn't create a new partition, nothing
4175  // happened.
4176  if (NewAI == &AI)
4177  return nullptr;
4178 
4179  // If we can't promote the alloca, iterate on it to check for new
4180  // refinements exposed by splitting the current alloca. Don't iterate on an
4181  // alloca which didn't actually change and didn't get promoted.
4182  Worklist.insert(NewAI);
4183  }
4184 
4185  return NewAI;
4186 }
4187 
4188 /// Walks the slices of an alloca and form partitions based on them,
4189 /// rewriting each of their uses.
4190 bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
4191  if (AS.begin() == AS.end())
4192  return false;
4193 
4194  unsigned NumPartitions = 0;
4195  bool Changed = false;
4196  const DataLayout &DL = AI.getModule()->getDataLayout();
4197 
4198  // First try to pre-split loads and stores.
4199  Changed |= presplitLoadsAndStores(AI, AS);
4200 
4201  // Now that we have identified any pre-splitting opportunities,
4202  // mark loads and stores unsplittable except for the following case.
4203  // We leave a slice splittable if all other slices are disjoint or fully
4204  // included in the slice, such as whole-alloca loads and stores.
4205  // If we fail to split these during pre-splitting, we want to force them
4206  // to be rewritten into a partition.
4207  bool IsSorted = true;
4208 
4209  uint64_t AllocaSize = DL.getTypeAllocSize(AI.getAllocatedType());
4210  const uint64_t MaxBitVectorSize = 1024;
4211  if (AllocaSize <= MaxBitVectorSize) {
4212  // If a byte boundary is included in any load or store, a slice starting or
4213  // ending at the boundary is not splittable.
4214  SmallBitVector SplittableOffset(AllocaSize + 1, true);
4215  for (Slice &S : AS)
4216  for (unsigned O = S.beginOffset() + 1;
4217  O < S.endOffset() && O < AllocaSize; O++)
4218  SplittableOffset.reset(O);
4219 
4220  for (Slice &S : AS) {
4221  if (!S.isSplittable())
4222  continue;
4223 
4224  if ((S.beginOffset() > AllocaSize || SplittableOffset[S.beginOffset()]) &&
4225  (S.endOffset() > AllocaSize || SplittableOffset[S.endOffset()]))
4226  continue;
4227 
4228  if (isa<LoadInst>(S.getUse()->getUser()) ||
4229  isa<StoreInst>(S.getUse()->getUser())) {
4230  S.makeUnsplittable();
4231  IsSorted = false;
4232  }
4233  }
4234  }
4235  else {
4236  // We only allow whole-alloca splittable loads and stores
4237  // for a large alloca to avoid creating too large BitVector.
4238  for (Slice &S : AS) {
4239  if (!S.isSplittable())
4240  continue;
4241 
4242  if (S.beginOffset() == 0 && S.endOffset() >= AllocaSize)
4243  continue;
4244 
4245  if (isa<LoadInst>(S.getUse()->getUser()) ||
4246  isa<StoreInst>(S.getUse()->getUser())) {
4247  S.makeUnsplittable();
4248  IsSorted = false;
4249  }
4250  }
4251  }
4252 
4253  if (!IsSorted)
4254  llvm::sort(AS);
4255 
4256  /// Describes the allocas introduced by rewritePartition in order to migrate
4257  /// the debug info.
4258  struct Fragment {
4259  AllocaInst *Alloca;
4260  uint64_t Offset;
4261  uint64_t Size;
4262  Fragment(AllocaInst *AI, uint64_t O, uint64_t S)
4263  : Alloca(AI), Offset(O), Size(S) {}
4264  };
4265  SmallVector<Fragment, 4> Fragments;
4266 
4267  // Rewrite each partition.
4268  for (auto &P : AS.partitions()) {
4269  if (AllocaInst *NewAI = rewritePartition(AI, AS, P)) {
4270  Changed = true;
4271  if (NewAI != &AI) {
4272  uint64_t SizeOfByte = 8;
4273  uint64_t AllocaSize = DL.getTypeSizeInBits(NewAI->getAllocatedType());
4274  // Don't include any padding.
4275  uint64_t Size = std::min(AllocaSize, P.size() * SizeOfByte);
4276  Fragments.push_back(Fragment(NewAI, P.beginOffset() * SizeOfByte, Size));
4277  }
4278  }
4279  ++NumPartitions;
4280  }
4281 
4282  NumAllocaPartitions += NumPartitions;
4283  MaxPartitionsPerAlloca.updateMax(NumPartitions);
4284 
4285  // Migrate debug information from the old alloca to the new alloca(s)
4286  // and the individual partitions.
4288  if (!DbgDeclares.empty()) {
4289  auto *Var = DbgDeclares.front()->getVariable();
4290  auto *Expr = DbgDeclares.front()->getExpression();
4291  auto VarSize = Var->getSizeInBits();
4292  DIBuilder DIB(*AI.getModule(), /*AllowUnresolved*/ false);
4293  uint64_t AllocaSize = DL.getTypeSizeInBits(AI.getAllocatedType());
4294  for (auto Fragment : Fragments) {
4295  // Create a fragment expression describing the new partition or reuse AI's
4296  // expression if there is only one partition.
4297  auto *FragmentExpr = Expr;
4298  if (Fragment.Size < AllocaSize || Expr->isFragment()) {
4299  // If this alloca is already a scalar replacement of a larger aggregate,
4300  // Fragment.Offset describes the offset inside the scalar.
4301  auto ExprFragment = Expr->getFragmentInfo();
4302  uint64_t Offset = ExprFragment ? ExprFragment->OffsetInBits : 0;
4303  uint64_t Start = Offset + Fragment.Offset;
4304  uint64_t Size = Fragment.Size;
4305  if (ExprFragment) {
4306  uint64_t AbsEnd =
4307  ExprFragment->OffsetInBits + ExprFragment->SizeInBits;
4308  if (Start >= AbsEnd)
4309  // No need to describe a SROAed padding.
4310  continue;
4311  Size = std::min(Size, AbsEnd - Start);
4312  }
4313  // The new, smaller fragment is stenciled out from the old fragment.
4314  if (auto OrigFragment = FragmentExpr->getFragmentInfo()) {
4315  assert(Start >= OrigFragment->OffsetInBits &&
4316  "new fragment is outside of original fragment");
4317  Start -= OrigFragment->OffsetInBits;
4318  }
4319 
4320  // The alloca may be larger than the variable.
4321  if (VarSize) {
4322  if (Size > *VarSize)
4323  Size = *VarSize;
4324  if (Size == 0 || Start + Size > *VarSize)
4325  continue;
4326  }
4327 
4328  // Avoid creating a fragment expression that covers the entire variable.
4329  if (!VarSize || *VarSize != Size) {
4330  if (auto E =
4331  DIExpression::createFragmentExpression(Expr, Start, Size))
4332  FragmentExpr = *E;
4333  else
4334  continue;
4335  }
4336  }
4337 
4338  // Remove any existing intrinsics describing the same alloca.
4339  for (DbgVariableIntrinsic *OldDII : FindDbgAddrUses(Fragment.Alloca))
4340  OldDII->eraseFromParent();
4341 
4342  DIB.insertDeclare(Fragment.Alloca, Var, FragmentExpr,
4343  DbgDeclares.front()->getDebugLoc(), &AI);
4344  }
4345  }
4346  return Changed;
4347 }
4348 
4349 /// Clobber a use with undef, deleting the used value if it becomes dead.
4350 void SROA::clobberUse(Use &U) {
4351  Value *OldV = U;
4352  // Replace the use with an undef value.
4353  U = UndefValue::get(OldV->getType());
4354 
4355  // Check for this making an instruction dead. We have to garbage collect
4356  // all the dead instructions to ensure the uses of any alloca end up being
4357  // minimal.
4358  if (Instruction *OldI = dyn_cast<Instruction>(OldV))
4359  if (isInstructionTriviallyDead(OldI)) {
4360  DeadInsts.insert(OldI);
4361  }
4362 }
4363 
4364 /// Analyze an alloca for SROA.
4365 ///
4366 /// This analyzes the alloca to ensure we can reason about it, builds
4367 /// the slices of the alloca, and then hands it off to be split and
4368 /// rewritten as needed.
4369 bool SROA::runOnAlloca(AllocaInst &AI) {
4370  LLVM_DEBUG(dbgs() << "SROA alloca: " << AI << "\n");
4371  ++NumAllocasAnalyzed;
4372 
4373  // Special case dead allocas, as they're trivial.
4374  if (AI.use_empty()) {
4375  AI.eraseFromParent();
4376  return true;
4377  }
4378  const DataLayout &DL = AI.getModule()->getDataLayout();
4379 
4380  // Skip alloca forms that this analysis can't handle.
4381  if (AI.isArrayAllocation() || !AI.getAllocatedType()->isSized() ||
4382  DL.getTypeAllocSize(AI.getAllocatedType()) == 0)
4383  return false;
4384 
4385  bool Changed = false;
4386 
4387  // First, split any FCA loads and stores touching this alloca to promote
4388  // better splitting and promotion opportunities.
4389  AggLoadStoreRewriter AggRewriter(DL);
4390  Changed |= AggRewriter.rewrite(AI);
4391 
4392  // Build the slices using a recursive instruction-visiting builder.
4393  AllocaSlices AS(DL, AI);
4394  LLVM_DEBUG(AS.print(dbgs()));
4395  if (AS.isEscaped())
4396  return Changed;
4397 
4398  // Delete all the dead users of this alloca before splitting and rewriting it.
4399  for (Instruction *DeadUser : AS.getDeadUsers()) {
4400  // Free up everything used by this instruction.
4401  for (Use &DeadOp : DeadUser->operands())
4402  clobberUse(DeadOp);
4403 
4404  // Now replace the uses of this instruction.
4405  DeadUser->replaceAllUsesWith(UndefValue::get(DeadUser->getType()));
4406 
4407  // And mark it for deletion.
4408  DeadInsts.insert(DeadUser);
4409  Changed = true;
4410  }
4411  for (Use *DeadOp : AS.getDeadOperands()) {
4412  clobberUse(*DeadOp);
4413  Changed = true;
4414  }
4415 
4416  // No slices to split. Leave the dead alloca for a later pass to clean up.
4417  if (AS.begin() == AS.end())
4418  return Changed;
4419 
4420  Changed |= splitAlloca(AI, AS);
4421 
4422  LLVM_DEBUG(dbgs() << " Speculating PHIs\n");
4423  while (!SpeculatablePHIs.empty())
4424  speculatePHINodeLoads(*SpeculatablePHIs.pop_back_val());
4425 
4426  LLVM_DEBUG(dbgs() << " Speculating Selects\n");
4427  while (!SpeculatableSelects.empty())
4428  speculateSelectInstLoads(*SpeculatableSelects.pop_back_val());
4429 
4430  return Changed;
4431 }
4432 
4433 /// Delete the dead instructions accumulated in this run.
4434 ///
4435 /// Recursively deletes the dead instructions we've accumulated. This is done
4436 /// at the very end to maximize locality of the recursive delete and to
4437 /// minimize the problems of invalidated instruction pointers as such pointers
4438 /// are used heavily in the intermediate stages of the algorithm.
4439 ///
4440 /// We also record the alloca instructions deleted here so that they aren't
4441 /// subsequently handed to mem2reg to promote.
4442 bool SROA::deleteDeadInstructions(
4443  SmallPtrSetImpl<AllocaInst *> &DeletedAllocas) {
4444  bool Changed = false;
4445  while (!DeadInsts.empty()) {
4446  Instruction *I = DeadInsts.pop_back_val();
4447  LLVM_DEBUG(dbgs() << "Deleting dead instruction: " << *I << "\n");
4448 
4449  // If the instruction is an alloca, find the possible dbg.declare connected
4450  // to it, and remove it too. We must do this before calling RAUW or we will
4451  // not be able to find it.
4452  if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
4453  DeletedAllocas.insert(AI);
4454  for (DbgVariableIntrinsic *OldDII : FindDbgAddrUses(AI))
4455  OldDII->eraseFromParent();
4456  }
4457 
4459 
4460  for (Use &Operand : I->operands())
4461  if (Instruction *U = dyn_cast<Instruction>(Operand)) {
4462  // Zero out the operand and see if it becomes trivially dead.
4463  Operand = nullptr;
4465  DeadInsts.insert(U);
4466  }
4467 
4468  ++NumDeleted;
4469  I->eraseFromParent();
4470  Changed = true;
4471  }
4472  return Changed;
4473 }
4474 
4475 /// Promote the allocas, using the best available technique.
4476 ///
4477 /// This attempts to promote whatever allocas have been identified as viable in
4478 /// the PromotableAllocas list. If that list is empty, there is nothing to do.
4479 /// This function returns whether any promotion occurred.
4480 bool SROA::promoteAllocas(Function &F) {
4481  if (PromotableAllocas.empty())
4482  return false;
4483 
4484  NumPromoted += PromotableAllocas.size();
4485 
4486  LLVM_DEBUG(dbgs() << "Promoting allocas with mem2reg...\n");
4487  PromoteMemToReg(PromotableAllocas, *DT, AC);
4488  PromotableAllocas.clear();
4489  return true;
4490 }
4491 
4492 PreservedAnalyses SROA::runImpl(Function &F, DominatorTree &RunDT,
4493  AssumptionCache &RunAC) {
4494  LLVM_DEBUG(dbgs() << "SROA function: " << F.getName() << "\n");
4495  C = &F.getContext();
4496  DT = &RunDT;
4497  AC = &RunAC;
4498 
4499  BasicBlock &EntryBB = F.getEntryBlock();
4500  for (BasicBlock::iterator I = EntryBB.begin(), E = std::prev(EntryBB.end());
4501  I != E; ++I) {
4502  if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
4503  Worklist.insert(AI);
4504  }
4505 
4506  bool Changed = false;
4507  // A set of deleted alloca instruction pointers which should be removed from
4508  // the list of promotable allocas.
4509  SmallPtrSet<AllocaInst *, 4> DeletedAllocas;
4510 
4511  do {
4512  while (!Worklist.empty()) {
4513  Changed |= runOnAlloca(*Worklist.pop_back_val());
4514  Changed |= deleteDeadInstructions(DeletedAllocas);
4515 
4516  // Remove the deleted allocas from various lists so that we don't try to
4517  // continue processing them.
4518  if (!DeletedAllocas.empty()) {
4519  auto IsInSet = [&](AllocaInst *AI) { return DeletedAllocas.count(AI); };
4520  Worklist.remove_if(IsInSet);
4521  PostPromotionWorklist.remove_if(IsInSet);
4522  PromotableAllocas.erase(llvm::remove_if(PromotableAllocas, IsInSet),
4523  PromotableAllocas.end());
4524  DeletedAllocas.clear();
4525  }
4526  }
4527 
4528  Changed |= promoteAllocas(F);
4529 
4530  Worklist = PostPromotionWorklist;
4531  PostPromotionWorklist.clear();
4532  } while (!Worklist.empty());
4533 
4534  if (!Changed)
4535  return PreservedAnalyses::all();
4536 
4537  PreservedAnalyses PA;
4538  PA.preserveSet<CFGAnalyses>();
4539  PA.preserve<GlobalsAA>();
4540  return PA;
4541 }
4542 
4544  return runImpl(F, AM.getResult<DominatorTreeAnalysis>(F),
4545  AM.getResult<AssumptionAnalysis>(F));
4546 }
4547 
4548 /// A legacy pass for the legacy pass manager that wraps the \c SROA pass.
4549 ///
4550 /// This is in the llvm namespace purely to allow it to be a friend of the \c
4551 /// SROA pass.
4553  /// The SROA implementation.
4554  SROA Impl;
4555 
4556 public:
4557  static char ID;
4558 
4561  }
4562 
4563  bool runOnFunction(Function &F) override {
4564  if (skipFunction(F))
4565  return false;
4566 
4567  auto PA = Impl.runImpl(
4568  F, getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
4569  getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F));
4570  return !PA.areAllPreserved();
4571  }
4572 
4573  void getAnalysisUsage(AnalysisUsage &AU) const override {
4577  AU.setPreservesCFG();
4578  }
4579 
4580  StringRef getPassName() const override { return "SROA"; }
4581 };
4582 
4583 char SROALegacyPass::ID = 0;
4584 
4586 
4588  "Scalar Replacement Of Aggregates", false, false)
4592  false, false)
Legacy wrapper pass to provide the GlobalsAAResult object.
static Value * getAdjustedPtr(IRBuilderTy &IRB, const DataLayout &DL, Value *Ptr, APInt Offset, Type *PointerTy, Twine NamePrefix)
Compute an adjusted pointer from Ptr by Offset bytes where the resulting pointer has PointerTy...
Definition: SROA.cpp:1553
static unsigned getBitWidth(Type *Ty, const DataLayout &DL)
Returns the bitwidth of the given scalar or pointer type.
static VectorType * isVectorPromotionViable(Partition &P, const DataLayout &DL)
Test whether the given alloca partitioning and range of slices can be promoted to a vector...
Definition: SROA.cpp:1850
iterator end() const
Definition: SROA.cpp:417
uint64_t CallInst * C
static Value * getNaturalGEPRecursively(IRBuilderTy &IRB, const DataLayout &DL, Value *Ptr, Type *Ty, APInt &Offset, Type *TargetTy, SmallVectorImpl< Value *> &Indices, Twine NamePrefix)
Recursively compute indices for a natural GEP.
Definition: SROA.cpp:1439
Value * getValueOperand()
Definition: Instructions.h:410
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:259
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
uint64_t getTypeStoreSizeInBits(Type *Ty) const
Returns the maximum number of bits that may be overwritten by storing the specified type; always a mu...
Definition: DataLayout.h:427
An iterator over partitions of the alloca&#39;s slices.
Definition: SROA.cpp:437
void setInt(IntType IntVal)
bool isSimple() const
Definition: Instructions.h:277
static bool runImpl(Function &F, TargetLibraryInfo &TLI, DominatorTree &DT)
This is the entry point for all transforms.
iterator_range< use_iterator > uses()
Definition: Value.h:355
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
unsigned getIndexSizeInBits(unsigned AS) const
Size in bits of index used for address calculation in getelementptr.
Definition: DataLayout.h:373
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
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:1563
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
Base class for instruction visitors.
Definition: InstVisitor.h:81
const_iterator begin(StringRef path, Style style=Style::native)
Get begin iterator over path.
Definition: Path.cpp:250
const Value * stripInBoundsOffsets() const
Strip off pointer casts and inbounds GEPs.
Definition: Value.cpp:589
uint64_t beginOffset() const
The start offset of this partition.
Definition: SROA.cpp:388
This is a &#39;bitvector&#39; (really, a variable-sized bit array), optimized for the case when the array is ...
PassT::Result & getResult(IRUnitT &IR, ExtraArgTs... ExtraArgs)
Get the result of an analysis pass for a given IR unit.
Definition: PassManager.h:770
This class represents lattice values for constants.
Definition: AllocatorList.h:24
PointerTy getPointer() const
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds...
Definition: Compiler.h:465
Type * getElementType(unsigned N) const
Definition: DerivedTypes.h:314
This is the interface for a simple mod/ref and alias analysis over globals.
EltTy front() const
bool isSized(SmallPtrSetImpl< Type *> *Visited=nullptr) const
Return true if it makes sense to take the size of this type.
Definition: Type.h:265
iterator begin() const
Definition: ArrayRef.h:137
constexpr char IsVolatile[]
Key for Kernel::Arg::Metadata::mIsVolatile.
APInt sdiv(const APInt &RHS) const
Signed division function for APInt.
Definition: APInt.cpp:1591
LLVM_NODISCARD size_t rfind(char C, size_t From=npos) const
Search for the last character C in the string.
Definition: StringRef.h:360
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
This file provides the interface for LLVM&#39;s Scalar Replacement of Aggregates pass.
void push_back(const T &Elt)
Definition: SmallVector.h:218
This provides a very simple, boring adaptor for a begin and end iterator into a range type...
void erase(iterator Start, iterator Stop)
Erase a range of slices.
Definition: SROA.cpp:266
bool isTriviallyEmpty() const
Check if this twine is trivially empty; a false return value does not necessarily mean the twine is e...
Definition: Twine.h:401
This class provides information about the result of a visit.
Definition: PtrUseVisitor.h:63
This class represents a function call, abstracting a target machine&#39;s calling convention.
static Value * extractInteger(const DataLayout &DL, IRBuilderTy &IRB, Value *V, IntegerType *Ty, uint64_t Offset, const Twine &Name)
Definition: SROA.cpp:2087
This file contains the declarations for metadata subclasses.
Representation of the alloca slices.
Definition: SROA.cpp:239
An immutable pass that tracks lazily created AssumptionCache objects.
unsigned getSourceAlignment() const
Instruction * getAbortingInst() const
Get the instruction causing the visit to abort.
Definition: PtrUseVisitor.h:84
SyncScope::ID getSyncScopeID() const
Returns the synchronization scope ID of this store instruction.
Definition: Instructions.h:385
gep_type_iterator gep_type_end(const User *GEP)
const Value * getTrueValue() const
void insert(ArrayRef< Slice > NewSlices)
Insert new slices for this alloca.
Definition: SROA.cpp:273
Value * getValue() const
A cache of @llvm.assume calls within a function.
AtomicOrdering getOrdering() const
Returns the ordering constraint of this load instruction.
Definition: Instructions.h:248
Offsets
Offsets in bytes from the start of the input buffer.
Definition: SIInstrInfo.h:1025
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:705
void deleteValue()
Delete a pointer to a generic Value.
Definition: Value.cpp:98
void setSource(Value *Ptr)
void setDest(Value *Ptr)
Set the specified arguments of the instruction.
This class wraps the llvm.memset intrinsic.
const Use & getOperandUse(unsigned i) const
Definition: User.h:183
unsigned second
Scalar Replacement Of Aggregates
Definition: SROA.cpp:4591
bool all_of(R &&range, UnaryPredicate P)
Provide wrappers to std::all_of which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1186
STATISTIC(NumFunctions, "Total number of functions")
Metadata node.
Definition: Metadata.h:864
Analysis pass which computes a DominatorTree.
Definition: Dominators.h:231
F(f)
unsigned getPointerAddressSpace() const
Get the address space of this pointer or pointer vector type.
Definition: DerivedTypes.h:503
An instruction for reading from memory.
Definition: Instructions.h:168
APInt zextOrTrunc(unsigned width) const
Zero extend or truncate to width.
Definition: APInt.cpp:876
Hexagon Common GEP
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:138
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:230
This defines the Use class.
void reserve(size_type N)
Definition: SmallVector.h:376
Value * getLength() const
void setAtomic(AtomicOrdering Ordering, SyncScope::ID SSID=SyncScope::System)
Sets the ordering constraint and the synchronization scope ID of this store instruction.
Definition: Instructions.h:396
bool isEscaped() const
Test whether a pointer to the allocation escapes our analysis.
Definition: SROA.cpp:248
TinyPtrVector - This class is specialized for cases where there are normally 0 or 1 element in a vect...
Definition: TinyPtrVector.h:31
bool isSafeToLoadUnconditionally(Value *V, unsigned Align, const DataLayout &DL, Instruction *ScanFrom=nullptr, const DominatorTree *DT=nullptr)
Return true if we know that executing a load from this value cannot trap.
Definition: Loads.cpp:201
op_iterator op_begin()
Definition: User.h:230
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:84
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1509
static unsigned getAdjustedAlignment(Instruction *I, uint64_t Offset, const DataLayout &DL)
Compute the adjusted alignment for a load or store from an offset.
Definition: SROA.cpp:1648
Builder for the alloca slices.
Definition: SROA.cpp:655
LLVMContext & getContext() const
Return the LLVMContext in which this type was uniqued.
Definition: Type.h:130
A templated base class for SmallPtrSet which provides the typesafe interface that is common across al...
Definition: SmallPtrSet.h:344
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:269
Value * getArgOperand(unsigned i) const
Definition: InstrTypes.h:1135
std::pair< iterator, bool > insert(const std::pair< KeyT, ValueT > &KV)
Definition: DenseMap.h:221
void setAtomic(AtomicOrdering Ordering, SyncScope::ID SSID=SyncScope::System)
Sets the ordering constraint and the synchronization scope ID of this load instruction.
Definition: Instructions.h:271
static bool isVectorPromotionViableForSlice(Partition &P, const Slice &S, VectorType *Ty, uint64_t ElementSize, const DataLayout &DL)
Test whether the given slice use can be promoted to a vector.
Definition: SROA.cpp:1775
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
Run the pass over the function.
Definition: SROA.cpp:4543
void * PointerTy
Definition: GenericValue.h:22
AnalysisUsage & addRequired()
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:529
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:51
void setPointer(PointerTy PtrVal)
bool isVolatile() const
Return true if this is a load from a volatile memory location.
Definition: Instructions.h:232
amdgpu Simplify well known AMD library false Value Value const Twine & Name
This class represents the LLVM &#39;select&#39; instruction.
Type * getPointerElementType() const
Definition: Type.h:376
const DataLayout & getDataLayout() const
Get the data layout for the module&#39;s target platform.
Definition: Module.cpp:371
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
unsigned getAlignment() const
Return the alignment of the memory that is being allocated by the instruction.
Definition: Instructions.h:113
ArrayRef< T > makeArrayRef(const T &OneElt)
Construct an ArrayRef from a single element.
Definition: ArrayRef.h:451
PointerType * getType() const
Overload to return most specific pointer type.
Definition: Instructions.h:97
Class to represent struct types.
Definition: DerivedTypes.h:201
A Use represents the edge between a Value definition and its users.
Definition: Use.h:56
static Type * getTypePartition(const DataLayout &DL, Type *Ty, uint64_t Offset, uint64_t Size)
Try to find a partition of the aggregate type passed in for a given offset and size.
Definition: SROA.cpp:3441
PointerType * getPointerTo(unsigned AddrSpace=0) const
Return a pointer to the current type.
Definition: Type.cpp:652
ArrayRef< Slice * > splitSliceTails() const
Get the sequence of split slice tails.
Definition: SROA.cpp:425
bool isAborted() const
Did we abort the visit early?
Definition: PtrUseVisitor.h:76
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:42
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:743
static Value * convertValue(const DataLayout &DL, IRBuilderTy &IRB, Value *V, Type *NewTy)
Generic routine to convert an SSA value to a value of a different type.
Definition: SROA.cpp:1725
A partition of the slices.
Definition: SROA.cpp:363
unsigned getDestAlignment() const
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: SROA.cpp:4573
uint64_t getNumElements() const
Definition: DerivedTypes.h:359
static StructType * get(LLVMContext &Context, ArrayRef< Type *> Elements, bool isPacked=false)
This static method is the primary way to create a literal StructType.
Definition: Type.cpp:342
This file implements a class to represent arbitrary precision integral constant values and operations...
bool runOnFunction(Function &F) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
Definition: SROA.cpp:4563
This file provides a collection of visitors which walk the (instruction) uses of a pointer...
static Constant * getZExt(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1665
unsigned getPointerAddressSpace() const
Returns the address space of the pointer operand.
Definition: Instructions.h:419
User * getUser() const LLVM_READONLY
Returns the User that contains this Use.
Definition: Use.cpp:41
bool visit(AllocaSlices::const_iterator I)
Definition: SROA.cpp:2306
A base class for visitors over the uses of a pointer value.
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:142
void copyNonnullMetadata(const LoadInst &OldLI, MDNode *N, LoadInst &NewLI)
Copy a nonnull metadata node to a new load instruction.
Definition: Local.cpp:2479
bool isInBounds() const
Determine whether the GEP has the inbounds flag.
SmallVectorImpl< Slice >::iterator iterator
Support for iterating over the slices.
Definition: SROA.cpp:252
const_iterator end() const
Definition: SROA.cpp:262
IntType getInt() const
void setLength(Value *L)
A legacy pass for the legacy pass manager that wraps the SROA pass.
Definition: SROA.cpp:4552
Class to represent array types.
Definition: DerivedTypes.h:369
This is the common base class for debug info intrinsics for variables.
Definition: IntrinsicInst.h:88
APInt sextOrTrunc(unsigned width) const
Sign extend or truncate to width.
Definition: APInt.cpp:884
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:221
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:33
const APInt & getValue() const
Return the constant as an APInt value reference.
Definition: Constants.h:138
ConstantFolder - Create constants with minimum, target independent, folding.
An instruction for storing to memory.
Definition: Instructions.h:321
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:203
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:429
void printUse(raw_ostream &OS, const_iterator I, StringRef Indent=" ") const
LLVM_NODISCARD LLVM_ATTRIBUTE_ALWAYS_INLINE StringRef substr(size_t Start, size_t N=npos) const
Return a reference to the substring from [Start, Start + N).
Definition: StringRef.h:598
static Constant * getUDiv(Constant *C1, Constant *C2, bool isExact=false)
Definition: Constants.cpp:2271
unsigned getBitWidth() const
Get the number of bits in this IntegerType.
Definition: DerivedTypes.h:66
Type::subtype_iterator element_iterator
Definition: DerivedTypes.h:301
CRTP base class which implements the entire standard iterator facade in terms of a minimal subset of ...
Definition: iterator.h:68
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:145
static bool canConvertValue(const DataLayout &DL, Type *OldTy, Type *NewTy)
Test whether we can convert a value from the old to the new type.
Definition: SROA.cpp:1674
unsigned getNumSuccessors() const
Return the number of successors that this instruction has.
Value * getOperand(unsigned i) const
Definition: User.h:170
Class to represent pointers.
Definition: DerivedTypes.h:467
auto count(R &&Range, const E &Element) -> typename std::iterator_traits< decltype(adl_begin(Range))>::difference_type
Wrapper function around std::count to count the number of times an element Element occurs in the give...
Definition: STLExtras.h:1252
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:304
iterator find(const_arg_type_t< KeyT > Val)
Definition: DenseMap.h:176
const BasicBlock & getEntryBlock() const
Definition: Function.h:640
constexpr uint64_t MinAlign(uint64_t A, uint64_t B)
A and B are either alignments or offsets.
Definition: MathExtras.h:610
an instruction for type-safe pointer arithmetic to access elements of arrays and structs ...
Definition: Instructions.h:854
IntegerType * getIntPtrType(LLVMContext &C, unsigned AddressSpace=0) const
Returns an integer type with size at least as big as that of a pointer in the given address space...
Definition: DataLayout.cpp:750
void getAAMetadata(AAMDNodes &N, bool Merge=false) const
Fills the AAMDNodes structure with AA metadata from this instruction.
Maximum number of bits that can be specified.
Definition: DerivedTypes.h:52
Scalar Replacement Of false
Definition: SROA.cpp:4591
iterator_range< partition_iterator > partitions()
#define P(N)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:423
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
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:154
const_iterator getFirstInsertionPt() const
Returns an iterator to the first instruction in this block that is suitable for inserting a non-PHI i...
Definition: BasicBlock.cpp:217
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:308
bool areAllPreserved() const
Test whether all analyses are preserved (and none are abandoned).
Definition: PassManager.h:322
void setAAMetadata(const AAMDNodes &N)
Sets the metadata on this instruction from the AAMDNodes structure.
Definition: Metadata.cpp:1265
LLVM Basic Block Representation.
Definition: BasicBlock.h:58
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
static unsigned getPointerOperandIndex()
Definition: Instructions.h:415
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:42
LLVM_NODISCARD bool empty() const
Definition: SmallPtrSet.h:92
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:129
ArrayRef< Use * > getDeadOperands() const
Access the dead operands referring to this alloca.
Definition: SROA.cpp:295
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool isPointerTy() const
True if this is an instance of PointerType.
Definition: Type.h:224
static bool isSafeSelectToSpeculate(SelectInst &SI)
Select instructions that use an alloca and are subsequently loaded can be rewritten to load both inpu...
Definition: SROA.cpp:1307
LLVM_NODISCARD size_t find_first_not_of(char C, size_t From=0) const
Find the first character in the string that is not C or npos if not found.
Definition: StringRef.cpp:250
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:371
bool mayHaveSideEffects() const
Return true if the instruction may have side effects.
Definition: Instruction.h:562
static Value * getNaturalGEPWithOffset(IRBuilderTy &IRB, const DataLayout &DL, Value *Ptr, APInt Offset, Type *TargetTy, SmallVectorImpl< Value *> &Indices, Twine NamePrefix)
Get a natural GEP from a base pointer to a particular offset and resulting in a particular type...
Definition: SROA.cpp:1513
static sys::TimePoint< std::chrono::seconds > now(bool Deterministic)
element_iterator element_end() const
Definition: DerivedTypes.h:304
DIExpression * getExpression() const
Represent the analysis usage information of a pass.
op_iterator op_end()
Definition: User.h:232
bool isLifetimeStartOrEnd() const
Return true if the instruction is a llvm.lifetime.start or llvm.lifetime.end marker.
static cl::opt< bool > SROAStrictInbounds("sroa-strict-inbounds", cl::init(false), cl::Hidden)
Hidden option to experiment with completely strict handling of inbounds GEPs.
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:1193
#define LLVM_ATTRIBUTE_UNUSED
Definition: Compiler.h:160
Analysis pass providing a never-invalidated alias analysis result.
static void replace(Module &M, GlobalVariable *Old, GlobalVariable *New)
void initializeSROALegacyPassPass(PassRegistry &)
sroa
Definition: SROA.cpp:4591
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
bool empty() const
op_range operands()
Definition: User.h:238
Value * getPointerOperand()
Definition: Instructions.h:285
unsigned getAddressSpace() const
Return the address space of the Pointer type.
Definition: DerivedTypes.h:495
static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val)
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:382
Class to represent integer types.
Definition: DerivedTypes.h:40
unsigned getIndexTypeSizeInBits(Type *Ty) const
Layout size of the index used in GEP calculation.
Definition: DataLayout.cpp:662
AllocaSliceRewriter(const DataLayout &DL, AllocaSlices &AS, SROA &Pass, AllocaInst &OldAI, AllocaInst &NewAI, uint64_t NewAllocaBeginOffset, uint64_t NewAllocaEndOffset, bool IsIntegerPromotable, VectorType *PromotableVecTy, SmallSetVector< PHINode *, 8 > &PHIUsers, SmallSetVector< SelectInst *, 8 > &SelectUsers)
Definition: SROA.cpp:2277
void setAlignment(unsigned Align)
auto remove_if(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range))
Provide wrappers to std::remove_if which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1226
const Value * getCondition() const
static Constant * getAllOnesValue(Type *Ty)
Definition: Constants.cpp:319
LLVMContext & getContext() const
getContext - Return a reference to the LLVMContext associated with this function. ...
Definition: Function.cpp:193
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1415
iterator erase(const_iterator CI)
Definition: SmallVector.h:445
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:160
size_t size() const
Definition: SmallVector.h:53
Value * getIncomingValue(unsigned i) const
Return incoming value number x.
static PointerType * getInt8PtrTy(LLVMContext &C, unsigned AS=0)
Definition: Type.cpp:220
bool isVolatile() const
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Type * getAllocatedType() const
Return the type that is being allocated by the instruction.
Definition: Instructions.h:106
static Value * getNaturalGEPWithType(IRBuilderTy &IRB, const DataLayout &DL, Value *BasePtr, Type *Ty, Type *TargetTy, SmallVectorImpl< Value *> &Indices, Twine NamePrefix)
Get a natural GEP off of the BasePtr walking through Ty toward TargetTy without changing the offset o...
Definition: SROA.cpp:1395
void sort(IteratorTy Start, IteratorTy End)
Definition: STLExtras.h:1116
void printSlice(raw_ostream &OS, const_iterator I, StringRef Indent=" ") const
static Type * stripAggregateTypeWrapping(const DataLayout &DL, Type *Ty)
Strip aggregate type wrapping.
Definition: SROA.cpp:3403
Intrinsic::ID getIntrinsicID() const
Return the intrinsic ID of this intrinsic.
Definition: IntrinsicInst.h:51
SmallBitVector & reset()
This provides the default implementation of the IRBuilder &#39;InsertHelper&#39; method that is called whenev...
Definition: IRBuilder.h:62
This is the superclass of the array and vector type classes.
Definition: DerivedTypes.h:343
A function analysis which provides an AssumptionCache.
iterator_range< T > make_range(T x, T y)
Convenience function for iterating over sub-ranges.
bool isPtrOrPtrVectorTy() const
Return true if this is a pointer type or a vector of pointer types.
Definition: Type.h:227
isPodLike - This is a type trait that is used to determine whether a given type can be copied around ...
Definition: ArrayRef.h:530
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:298
print lazy value Lazy Value Info Printer Pass
This is the common base class for memset/memcpy/memmove.
Iterator for intrusive lists based on ilist_node.
uint64_t getLimitedValue(uint64_t Limit=~0ULL) const
getLimitedValue - If the value is smaller than the specified limit, return it, otherwise return the l...
Definition: Constants.h:251
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
TinyPtrVector< DbgVariableIntrinsic * > FindDbgAddrUses(Value *V)
Finds all intrinsics declaring local variables as living in the memory that &#39;V&#39; points to...
Definition: Local.cpp:1473
iterator end()
Definition: BasicBlock.h:271
AllocaSlices(const DataLayout &DL, AllocaInst &AI)
Construct the slices of a particular alloca.
Module.h This file contains the declarations for the Module class.
Instruction * user_back()
Specialize the methods defined in Value, as we know that an instruction can only be used by other ins...
Definition: Instruction.h:64
partition_iterator & operator++()
Definition: SROA.cpp:610
static Value * insertVector(IRBuilderTy &IRB, Value *Old, Value *V, unsigned BeginIndex, const Twine &Name)
Definition: SROA.cpp:2167
iterator end() const
Definition: ArrayRef.h:138
bool isLegalInteger(uint64_t Width) const
Returns true if the specified type is known to be a native integer type supported by the CPU...
Definition: DataLayout.h:243
unsigned getABITypeAlignment(Type *Ty) const
Returns the minimum ABI-required alignment for the specified type.
Definition: DataLayout.cpp:730
A collection of metadata nodes that might be associated with a memory access used by the alias-analys...
Definition: Metadata.h:644
iterator begin() const
Definition: SROA.cpp:416
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:381
uint64_t getSizeInBytes() const
Definition: DataLayout.h:537
SmallVectorImpl< Slice >::const_iterator const_iterator
Definition: SROA.cpp:258
static IntegerType * getIntNTy(LLVMContext &C, unsigned N)
Definition: Type.cpp:180
SliceBuilder(const DataLayout &DL, AllocaInst &AI, AllocaSlices &AS)
Definition: SROA.cpp:671
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:622
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.
unsigned getNumIncomingValues() const
Return the number of incoming edges.
bool uge(const APInt &RHS) const
Unsigned greater or equal comparison.
Definition: APInt.h:1293
void setOperand(unsigned i, Value *Val)
Definition: User.h:175
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:941
A range adaptor for a pair of iterators.
Class to represent vector types.
Definition: DerivedTypes.h:393
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
Class for arbitrary precision integers.
Definition: APInt.h:70
static bool isIntegerWideningViableForSlice(const Slice &S, uint64_t AllocBeginOffset, Type *AllocaTy, const DataLayout &DL, bool &WholeAllocaOp)
Test whether a slice of an alloca is valid for integer widening.
Definition: SROA.cpp:1958
iterator_range< user_iterator > users()
Definition: Value.h:400
#define NDEBUG
Definition: regutils.h:48
Represents analyses that only rely on functions&#39; control flow.
Definition: PassManager.h:115
const Value * getFalseValue() const
element_iterator element_begin() const
Definition: DerivedTypes.h:303
static Value * insertInteger(const DataLayout &DL, IRBuilderTy &IRB, Value *Old, Value *V, uint64_t Offset, const Twine &Name)
Definition: SROA.cpp:2110
bool isNonIntegralPointerType(PointerType *PT) const
Definition: DataLayout.h:349
const_iterator begin() const
Definition: SROA.cpp:261
static Type * findCommonType(AllocaSlices::const_iterator B, AllocaSlices::const_iterator E, uint64_t EndOffset)
Walk the range of a partitioning looking for a common type to cover this sequence of slices...
Definition: SROA.cpp:1108
uint64_t getTypeSizeInBits(Type *Ty) const
Size examples:
Definition: DataLayout.h:568
static Value * foldPHINodeOrSelectInst(Instruction &I)
A helper that folds a PHI node or a select.
Definition: SROA.cpp:643
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:436
Virtual Register Rewriter
Definition: VirtRegMap.cpp:222
bool operator!=(uint64_t V1, const APInt &V2)
Definition: APInt.h:1969
INITIALIZE_PASS_BEGIN(SROALegacyPass, "sroa", "Scalar Replacement Of Aggregates", false, false) INITIALIZE_PASS_END(SROALegacyPass
bool ugt(const APInt &RHS) const
Unsigned greather than comparison.
Definition: APInt.h:1255
static bool isZero(Value *V, const DataLayout &DL, DominatorTree *DT, AssumptionCache *AC)
Definition: Lint.cpp:546
This class wraps the llvm.memcpy/memmove intrinsics.
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:133
bool isPacked() const
Definition: DerivedTypes.h:261
bool isVolatile() const
Return true if this is a store to a volatile memory location.
Definition: Instructions.h:354
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:311
static const size_t npos
Definition: StringRef.h:51
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:551
unsigned getAlignment() const
Return the alignment of the access that is being performed.
Definition: Instructions.h:241
unsigned getIntegerBitWidth() const
Definition: DerivedTypes.h:97
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:56
AtomicOrdering getOrdering() const
Returns the ordering constraint of this store instruction.
Definition: Instructions.h:373
StringRef getPassName() const override
getPassName - Return a nice clean name for a pass.
Definition: SROA.cpp:4580
uint64_t getLimitedValue(uint64_t Limit=UINT64_MAX) const
If this value is smaller than the specified limit, return it, otherwise return the limit value...
Definition: APInt.h:482
Visitor to rewrite instructions using p particular slice of an alloca to use a new alloca...
Definition: SROA.cpp:2220
void preserveSet()
Mark an analysis set as preserved.
Definition: PassManager.h:190
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
BasicBlock * getIncomingBlock(unsigned i) const
Return incoming basic block number i.
static void speculateSelectInstLoads(SelectInst &SI)
Definition: SROA.cpp:1329
SyncScope::ID getSyncScopeID() const
Returns the synchronization scope ID of this load instruction.
Definition: Instructions.h:260
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
iterator end()
Definition: DenseMap.h:109
FunctionPass * createSROAPass()
Definition: SROA.cpp:4585
uint64_t endOffset() const
The end offset of this partition.
Definition: SROA.cpp:393
Instruction * getEscapingInst() const
Get the instruction causing the pointer to escape.
Definition: PtrUseVisitor.h:89
static ArrayType * get(Type *ElementType, uint64_t NumElements)
This static method is the primary way to construct an ArrayType.
Definition: Type.cpp:581
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
uint32_t Size
Definition: Profile.cpp:47
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:175
DILocalVariable * getVariable() const
static Value * extractVector(IRBuilderTy &IRB, Value *V, unsigned BeginIndex, unsigned EndIndex, const Twine &Name)
Definition: SROA.cpp:2141
size_type count(const_arg_type_t< KeyT > Val) const
Return 1 if the specified key is in the map, 0 otherwise.
Definition: DenseMap.h:171
unsigned getAlignment() const
Return the alignment of the access that is being performed.
Definition: Instructions.h:366
std::string str() const
Return the twine contents as a std::string.
Definition: Twine.cpp:18
ValueT lookup(const_arg_type_t< KeyT > Val) const
lookup - Return the entry for the specified key, or a default constructed value if no such entry exis...
Definition: DenseMap.h:211
unsigned getPointerAddressSpace() const
Returns the address space of the pointer operand.
Definition: Instructions.h:291
static unsigned getPointerOperandIndex()
Definition: Instructions.h:287
bool isArrayAllocation() const
Return true if there is an allocation size parameter to the allocation instruction that is not 1...
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
user_iterator user_begin()
Definition: Value.h:376
Definition: JSON.cpp:592
bool operator<(int64_t V1, const APSInt &V2)
Definition: APSInt.h:326
bool isSingleValueType() const
Return true if the type is a valid type for a register in codegen.
Definition: Type.h:250
bool isInstructionTriviallyDead(Instruction *I, const TargetLibraryInfo *TLI=nullptr)
Return true if the result produced by the instruction is not used, and the instruction has no side ef...
Definition: Local.cpp:349
LLVM Value Representation.
Definition: Value.h:73
void setAlignment(unsigned Align)
static Value * buildGEP(IRBuilderTy &IRB, Value *BasePtr, SmallVectorImpl< Value *> &Indices, Twine NamePrefix)
Build a GEP out of a base pointer and indices.
Definition: SROA.cpp:1372
uint64_t getTypeStoreSize(Type *Ty) const
Returns the maximum number of bytes that may be overwritten by storing the specified type...
Definition: DataLayout.h:419
static bool isSafePHIToSpeculate(PHINode &PN)
PHI instructions that use an alloca and are subsequently loaded can be rewritten to load both input p...
Definition: SROA.cpp:1175
unsigned getOpcode() const
Return the opcode for this Instruction or ConstantExpr.
Definition: Operator.h:41
void copyMetadata(const Instruction &SrcInst, ArrayRef< unsigned > WL=ArrayRef< unsigned >())
Copy metadata from SrcInst to this instruction.
static VectorType * get(Type *ElementType, unsigned NumElements)
This static method is the primary way to construct an VectorType.
Definition: Type.cpp:606
std::underlying_type< E >::type Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:81
void InsertHelper(Instruction *I, const Twine &Name, BasicBlock *BB, BasicBlock::iterator InsertPt) const
Definition: IRBuilder.h:64
static void speculatePHINodeLoads(PHINode &PN)
Definition: SROA.cpp:1239
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:46
void PromoteMemToReg(ArrayRef< AllocaInst *> Allocas, DominatorTree &DT, AssumptionCache *AC=nullptr)
Promote the specified list of alloca instructions into scalar registers, inserting PHI nodes as appro...
PtrInfo visitPtr(Instruction &I)
Recursively visit the uses of the given pointer.
An optimization pass providing Scalar Replacement of Aggregates.
Definition: SROA.h:66
Type * getElementType() const
Definition: DerivedTypes.h:360
static cl::opt< bool > SROARandomShuffleSlices("sroa-random-shuffle-slices", cl::init(false), cl::Hidden)
Hidden option to enable randomly shuffling the slices to help uncover instability in their order...
uint64_t size() const
The size of the partition.
Definition: SROA.cpp:398
IRTranslator LLVM IR MI
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:413
bool empty() const
Test whether this partition contains no slices, and merely spans a region occupied by split slices...
Definition: SROA.cpp:405
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
void setSourceAlignment(unsigned Align)
A container for analyses that lazily runs them and caches their results.
void print(raw_ostream &OS, const_iterator I, StringRef Indent=" ") const
Type * getArrayElementType() const
Definition: Type.h:365
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:260
static bool isIntegerWideningViable(Partition &P, Type *AllocaTy, const DataLayout &DL)
Test whether the given alloca partition&#39;s integer operations can be widened to promotable ones...
Definition: SROA.cpp:2045
bool operator==(uint64_t V1, const APInt &V2)
Definition: