LLVM  3.7.0
ScalarReplAggregates.cpp
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1 //===- ScalarReplAggregates.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 //
10 // This transformation implements the well known scalar replacement of
11 // aggregates transformation. This xform breaks up alloca instructions of
12 // aggregate type (structure or array) into individual alloca instructions for
13 // each member (if possible). Then, if possible, it transforms the individual
14 // alloca instructions into nice clean scalar SSA form.
15 //
16 // This combines a simple SRoA algorithm with the Mem2Reg algorithm because they
17 // often interact, especially for C++ programs. As such, iterating between
18 // SRoA, then Mem2Reg until we run out of things to promote works well.
19 //
20 //===----------------------------------------------------------------------===//
21 
22 #include "llvm/Transforms/Scalar.h"
23 #include "llvm/ADT/SetVector.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/Statistic.h"
27 #include "llvm/Analysis/Loads.h"
29 #include "llvm/IR/CallSite.h"
30 #include "llvm/IR/Constants.h"
31 #include "llvm/IR/DIBuilder.h"
32 #include "llvm/IR/DataLayout.h"
33 #include "llvm/IR/DebugInfo.h"
34 #include "llvm/IR/DerivedTypes.h"
35 #include "llvm/IR/Dominators.h"
36 #include "llvm/IR/Function.h"
38 #include "llvm/IR/GlobalVariable.h"
39 #include "llvm/IR/IRBuilder.h"
40 #include "llvm/IR/Instructions.h"
41 #include "llvm/IR/IntrinsicInst.h"
42 #include "llvm/IR/LLVMContext.h"
43 #include "llvm/IR/Module.h"
44 #include "llvm/IR/Operator.h"
45 #include "llvm/Pass.h"
46 #include "llvm/Support/Debug.h"
53 using namespace llvm;
54 
55 #define DEBUG_TYPE "scalarrepl"
56 
57 STATISTIC(NumReplaced, "Number of allocas broken up");
58 STATISTIC(NumPromoted, "Number of allocas promoted");
59 STATISTIC(NumAdjusted, "Number of scalar allocas adjusted to allow promotion");
60 STATISTIC(NumConverted, "Number of aggregates converted to scalar");
61 
62 namespace {
63  struct SROA : public FunctionPass {
64  SROA(int T, bool hasDT, char &ID, int ST, int AT, int SLT)
65  : FunctionPass(ID), HasDomTree(hasDT) {
66  if (T == -1)
67  SRThreshold = 128;
68  else
69  SRThreshold = T;
70  if (ST == -1)
71  StructMemberThreshold = 32;
72  else
73  StructMemberThreshold = ST;
74  if (AT == -1)
75  ArrayElementThreshold = 8;
76  else
77  ArrayElementThreshold = AT;
78  if (SLT == -1)
79  // Do not limit the scalar integer load size if no threshold is given.
80  ScalarLoadThreshold = -1;
81  else
82  ScalarLoadThreshold = SLT;
83  }
84 
85  bool runOnFunction(Function &F) override;
86 
87  bool performScalarRepl(Function &F);
88  bool performPromotion(Function &F);
89 
90  private:
91  bool HasDomTree;
92 
93  /// DeadInsts - Keep track of instructions we have made dead, so that
94  /// we can remove them after we are done working.
95  SmallVector<Value*, 32> DeadInsts;
96 
97  /// AllocaInfo - When analyzing uses of an alloca instruction, this captures
98  /// information about the uses. All these fields are initialized to false
99  /// and set to true when something is learned.
100  struct AllocaInfo {
101  /// The alloca to promote.
102  AllocaInst *AI;
103 
104  /// CheckedPHIs - This is a set of verified PHI nodes, to prevent infinite
105  /// looping and avoid redundant work.
106  SmallPtrSet<PHINode*, 8> CheckedPHIs;
107 
108  /// isUnsafe - This is set to true if the alloca cannot be SROA'd.
109  bool isUnsafe : 1;
110 
111  /// isMemCpySrc - This is true if this aggregate is memcpy'd from.
112  bool isMemCpySrc : 1;
113 
114  /// isMemCpyDst - This is true if this aggregate is memcpy'd into.
115  bool isMemCpyDst : 1;
116 
117  /// hasSubelementAccess - This is true if a subelement of the alloca is
118  /// ever accessed, or false if the alloca is only accessed with mem
119  /// intrinsics or load/store that only access the entire alloca at once.
120  bool hasSubelementAccess : 1;
121 
122  /// hasALoadOrStore - This is true if there are any loads or stores to it.
123  /// The alloca may just be accessed with memcpy, for example, which would
124  /// not set this.
125  bool hasALoadOrStore : 1;
126 
127  explicit AllocaInfo(AllocaInst *ai)
128  : AI(ai), isUnsafe(false), isMemCpySrc(false), isMemCpyDst(false),
129  hasSubelementAccess(false), hasALoadOrStore(false) {}
130  };
131 
132  /// SRThreshold - The maximum alloca size to considered for SROA.
133  unsigned SRThreshold;
134 
135  /// StructMemberThreshold - The maximum number of members a struct can
136  /// contain to be considered for SROA.
137  unsigned StructMemberThreshold;
138 
139  /// ArrayElementThreshold - The maximum number of elements an array can
140  /// have to be considered for SROA.
141  unsigned ArrayElementThreshold;
142 
143  /// ScalarLoadThreshold - The maximum size in bits of scalars to load when
144  /// converting to scalar
145  unsigned ScalarLoadThreshold;
146 
147  void MarkUnsafe(AllocaInfo &I, Instruction *User) {
148  I.isUnsafe = true;
149  DEBUG(dbgs() << " Transformation preventing inst: " << *User << '\n');
150  }
151 
152  bool isSafeAllocaToScalarRepl(AllocaInst *AI);
153 
154  void isSafeForScalarRepl(Instruction *I, uint64_t Offset, AllocaInfo &Info);
155  void isSafePHISelectUseForScalarRepl(Instruction *User, uint64_t Offset,
156  AllocaInfo &Info);
157  void isSafeGEP(GetElementPtrInst *GEPI, uint64_t &Offset, AllocaInfo &Info);
158  void isSafeMemAccess(uint64_t Offset, uint64_t MemSize,
159  Type *MemOpType, bool isStore, AllocaInfo &Info,
160  Instruction *TheAccess, bool AllowWholeAccess);
161  bool TypeHasComponent(Type *T, uint64_t Offset, uint64_t Size,
162  const DataLayout &DL);
163  uint64_t FindElementAndOffset(Type *&T, uint64_t &Offset, Type *&IdxTy,
164  const DataLayout &DL);
165 
166  void DoScalarReplacement(AllocaInst *AI,
167  std::vector<AllocaInst*> &WorkList);
168  void DeleteDeadInstructions();
169 
170  void RewriteForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset,
172  void RewriteBitCast(BitCastInst *BC, AllocaInst *AI, uint64_t Offset,
174  void RewriteGEP(GetElementPtrInst *GEPI, AllocaInst *AI, uint64_t Offset,
176  void RewriteLifetimeIntrinsic(IntrinsicInst *II, AllocaInst *AI,
177  uint64_t Offset,
179  void RewriteMemIntrinUserOfAlloca(MemIntrinsic *MI, Instruction *Inst,
180  AllocaInst *AI,
182  void RewriteStoreUserOfWholeAlloca(StoreInst *SI, AllocaInst *AI,
184  void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI,
186  bool ShouldAttemptScalarRepl(AllocaInst *AI);
187  };
188 
189  // SROA_DT - SROA that uses DominatorTree.
190  struct SROA_DT : public SROA {
191  static char ID;
192  public:
193  SROA_DT(int T = -1, int ST = -1, int AT = -1, int SLT = -1) :
194  SROA(T, true, ID, ST, AT, SLT) {
196  }
197 
198  // getAnalysisUsage - This pass does not require any passes, but we know it
199  // will not alter the CFG, so say so.
200  void getAnalysisUsage(AnalysisUsage &AU) const override {
203  AU.setPreservesCFG();
204  }
205  };
206 
207  // SROA_SSAUp - SROA that uses SSAUpdater.
208  struct SROA_SSAUp : public SROA {
209  static char ID;
210  public:
211  SROA_SSAUp(int T = -1, int ST = -1, int AT = -1, int SLT = -1) :
212  SROA(T, false, ID, ST, AT, SLT) {
214  }
215 
216  // getAnalysisUsage - This pass does not require any passes, but we know it
217  // will not alter the CFG, so say so.
218  void getAnalysisUsage(AnalysisUsage &AU) const override {
220  AU.setPreservesCFG();
221  }
222  };
223 
224 }
225 
226 char SROA_DT::ID = 0;
227 char SROA_SSAUp::ID = 0;
228 
229 INITIALIZE_PASS_BEGIN(SROA_DT, "scalarrepl",
230  "Scalar Replacement of Aggregates (DT)", false, false)
234  "Scalar Replacement of Aggregates (DT)", false, false)
235 
236 INITIALIZE_PASS_BEGIN(SROA_SSAUp, "scalarrepl-ssa",
237  "Scalar Replacement of Aggregates (SSAUp)", false, false)
239 INITIALIZE_PASS_END(SROA_SSAUp, "scalarrepl-ssa",
240  "Scalar Replacement of Aggregates (SSAUp)", false, false)
241 
242 // Public interface to the ScalarReplAggregates pass
244  bool UseDomTree,
245  int StructMemberThreshold,
246  int ArrayElementThreshold,
247  int ScalarLoadThreshold) {
248  if (UseDomTree)
249  return new SROA_DT(Threshold, StructMemberThreshold, ArrayElementThreshold,
250  ScalarLoadThreshold);
251  return new SROA_SSAUp(Threshold, StructMemberThreshold,
252  ArrayElementThreshold, ScalarLoadThreshold);
253 }
254 
255 
256 //===----------------------------------------------------------------------===//
257 // Convert To Scalar Optimization.
258 //===----------------------------------------------------------------------===//
259 
260 namespace {
261 /// ConvertToScalarInfo - This class implements the "Convert To Scalar"
262 /// optimization, which scans the uses of an alloca and determines if it can
263 /// rewrite it in terms of a single new alloca that can be mem2reg'd.
264 class ConvertToScalarInfo {
265  /// AllocaSize - The size of the alloca being considered in bytes.
266  unsigned AllocaSize;
267  const DataLayout &DL;
268  unsigned ScalarLoadThreshold;
269 
270  /// IsNotTrivial - This is set to true if there is some access to the object
271  /// which means that mem2reg can't promote it.
272  bool IsNotTrivial;
273 
274  /// ScalarKind - Tracks the kind of alloca being considered for promotion,
275  /// computed based on the uses of the alloca rather than the LLVM type system.
276  enum {
277  Unknown,
278 
279  // Accesses via GEPs that are consistent with element access of a vector
280  // type. This will not be converted into a vector unless there is a later
281  // access using an actual vector type.
282  ImplicitVector,
283 
284  // Accesses via vector operations and GEPs that are consistent with the
285  // layout of a vector type.
286  Vector,
287 
288  // An integer bag-of-bits with bitwise operations for insertion and
289  // extraction. Any combination of types can be converted into this kind
290  // of scalar.
291  Integer
292  } ScalarKind;
293 
294  /// VectorTy - This tracks the type that we should promote the vector to if
295  /// it is possible to turn it into a vector. This starts out null, and if it
296  /// isn't possible to turn into a vector type, it gets set to VoidTy.
297  VectorType *VectorTy;
298 
299  /// HadNonMemTransferAccess - True if there is at least one access to the
300  /// alloca that is not a MemTransferInst. We don't want to turn structs into
301  /// large integers unless there is some potential for optimization.
302  bool HadNonMemTransferAccess;
303 
304  /// HadDynamicAccess - True if some element of this alloca was dynamic.
305  /// We don't yet have support for turning a dynamic access into a large
306  /// integer.
307  bool HadDynamicAccess;
308 
309 public:
310  explicit ConvertToScalarInfo(unsigned Size, const DataLayout &DL,
311  unsigned SLT)
312  : AllocaSize(Size), DL(DL), ScalarLoadThreshold(SLT), IsNotTrivial(false),
313  ScalarKind(Unknown), VectorTy(nullptr), HadNonMemTransferAccess(false),
314  HadDynamicAccess(false) { }
315 
316  AllocaInst *TryConvert(AllocaInst *AI);
317 
318 private:
319  bool CanConvertToScalar(Value *V, uint64_t Offset, Value* NonConstantIdx);
320  void MergeInTypeForLoadOrStore(Type *In, uint64_t Offset);
321  bool MergeInVectorType(VectorType *VInTy, uint64_t Offset);
322  void ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI, uint64_t Offset,
323  Value *NonConstantIdx);
324 
325  Value *ConvertScalar_ExtractValue(Value *NV, Type *ToType,
326  uint64_t Offset, Value* NonConstantIdx,
327  IRBuilder<> &Builder);
328  Value *ConvertScalar_InsertValue(Value *StoredVal, Value *ExistingVal,
329  uint64_t Offset, Value* NonConstantIdx,
330  IRBuilder<> &Builder);
331 };
332 } // end anonymous namespace.
333 
334 
335 /// TryConvert - Analyze the specified alloca, and if it is safe to do so,
336 /// rewrite it to be a new alloca which is mem2reg'able. This returns the new
337 /// alloca if possible or null if not.
338 AllocaInst *ConvertToScalarInfo::TryConvert(AllocaInst *AI) {
339  // If we can't convert this scalar, or if mem2reg can trivially do it, bail
340  // out.
341  if (!CanConvertToScalar(AI, 0, nullptr) || !IsNotTrivial)
342  return nullptr;
343 
344  // If an alloca has only memset / memcpy uses, it may still have an Unknown
345  // ScalarKind. Treat it as an Integer below.
346  if (ScalarKind == Unknown)
347  ScalarKind = Integer;
348 
349  if (ScalarKind == Vector && VectorTy->getBitWidth() != AllocaSize * 8)
350  ScalarKind = Integer;
351 
352  // If we were able to find a vector type that can handle this with
353  // insert/extract elements, and if there was at least one use that had
354  // a vector type, promote this to a vector. We don't want to promote
355  // random stuff that doesn't use vectors (e.g. <9 x double>) because then
356  // we just get a lot of insert/extracts. If at least one vector is
357  // involved, then we probably really do have a union of vector/array.
358  Type *NewTy;
359  if (ScalarKind == Vector) {
360  assert(VectorTy && "Missing type for vector scalar.");
361  DEBUG(dbgs() << "CONVERT TO VECTOR: " << *AI << "\n TYPE = "
362  << *VectorTy << '\n');
363  NewTy = VectorTy; // Use the vector type.
364  } else {
365  unsigned BitWidth = AllocaSize * 8;
366 
367  // Do not convert to scalar integer if the alloca size exceeds the
368  // scalar load threshold.
369  if (BitWidth > ScalarLoadThreshold)
370  return nullptr;
371 
372  if ((ScalarKind == ImplicitVector || ScalarKind == Integer) &&
373  !HadNonMemTransferAccess && !DL.fitsInLegalInteger(BitWidth))
374  return nullptr;
375  // Dynamic accesses on integers aren't yet supported. They need us to shift
376  // by a dynamic amount which could be difficult to work out as we might not
377  // know whether to use a left or right shift.
378  if (ScalarKind == Integer && HadDynamicAccess)
379  return nullptr;
380 
381  DEBUG(dbgs() << "CONVERT TO SCALAR INTEGER: " << *AI << "\n");
382  // Create and insert the integer alloca.
383  NewTy = IntegerType::get(AI->getContext(), BitWidth);
384  }
385  AllocaInst *NewAI = new AllocaInst(NewTy, nullptr, "",
386  AI->getParent()->begin());
387  ConvertUsesToScalar(AI, NewAI, 0, nullptr);
388  return NewAI;
389 }
390 
391 /// MergeInTypeForLoadOrStore - Add the 'In' type to the accumulated vector type
392 /// (VectorTy) so far at the offset specified by Offset (which is specified in
393 /// bytes).
394 ///
395 /// There are two cases we handle here:
396 /// 1) A union of vector types of the same size and potentially its elements.
397 /// Here we turn element accesses into insert/extract element operations.
398 /// This promotes a <4 x float> with a store of float to the third element
399 /// into a <4 x float> that uses insert element.
400 /// 2) A fully general blob of memory, which we turn into some (potentially
401 /// large) integer type with extract and insert operations where the loads
402 /// and stores would mutate the memory. We mark this by setting VectorTy
403 /// to VoidTy.
404 void ConvertToScalarInfo::MergeInTypeForLoadOrStore(Type *In,
405  uint64_t Offset) {
406  // If we already decided to turn this into a blob of integer memory, there is
407  // nothing to be done.
408  if (ScalarKind == Integer)
409  return;
410 
411  // If this could be contributing to a vector, analyze it.
412 
413  // If the In type is a vector that is the same size as the alloca, see if it
414  // matches the existing VecTy.
415  if (VectorType *VInTy = dyn_cast<VectorType>(In)) {
416  if (MergeInVectorType(VInTy, Offset))
417  return;
418  } else if (In->isFloatTy() || In->isDoubleTy() ||
419  (In->isIntegerTy() && In->getPrimitiveSizeInBits() >= 8 &&
421  // Full width accesses can be ignored, because they can always be turned
422  // into bitcasts.
423  unsigned EltSize = In->getPrimitiveSizeInBits()/8;
424  if (EltSize == AllocaSize)
425  return;
426 
427  // If we're accessing something that could be an element of a vector, see
428  // if the implied vector agrees with what we already have and if Offset is
429  // compatible with it.
430  if (Offset % EltSize == 0 && AllocaSize % EltSize == 0 &&
431  (!VectorTy || EltSize == VectorTy->getElementType()
432  ->getPrimitiveSizeInBits()/8)) {
433  if (!VectorTy) {
434  ScalarKind = ImplicitVector;
435  VectorTy = VectorType::get(In, AllocaSize/EltSize);
436  }
437  return;
438  }
439  }
440 
441  // Otherwise, we have a case that we can't handle with an optimized vector
442  // form. We can still turn this into a large integer.
443  ScalarKind = Integer;
444 }
445 
446 /// MergeInVectorType - Handles the vector case of MergeInTypeForLoadOrStore,
447 /// returning true if the type was successfully merged and false otherwise.
448 bool ConvertToScalarInfo::MergeInVectorType(VectorType *VInTy,
449  uint64_t Offset) {
450  if (VInTy->getBitWidth()/8 == AllocaSize && Offset == 0) {
451  // If we're storing/loading a vector of the right size, allow it as a
452  // vector. If this the first vector we see, remember the type so that
453  // we know the element size. If this is a subsequent access, ignore it
454  // even if it is a differing type but the same size. Worst case we can
455  // bitcast the resultant vectors.
456  if (!VectorTy)
457  VectorTy = VInTy;
458  ScalarKind = Vector;
459  return true;
460  }
461 
462  return false;
463 }
464 
465 /// CanConvertToScalar - V is a pointer. If we can convert the pointee and all
466 /// its accesses to a single vector type, return true and set VecTy to
467 /// the new type. If we could convert the alloca into a single promotable
468 /// integer, return true but set VecTy to VoidTy. Further, if the use is not a
469 /// completely trivial use that mem2reg could promote, set IsNotTrivial. Offset
470 /// is the current offset from the base of the alloca being analyzed.
471 ///
472 /// If we see at least one access to the value that is as a vector type, set the
473 /// SawVec flag.
474 bool ConvertToScalarInfo::CanConvertToScalar(Value *V, uint64_t Offset,
475  Value* NonConstantIdx) {
476  for (User *U : V->users()) {
477  Instruction *UI = cast<Instruction>(U);
478 
479  if (LoadInst *LI = dyn_cast<LoadInst>(UI)) {
480  // Don't break volatile loads.
481  if (!LI->isSimple())
482  return false;
483  // Don't touch MMX operations.
484  if (LI->getType()->isX86_MMXTy())
485  return false;
486  HadNonMemTransferAccess = true;
487  MergeInTypeForLoadOrStore(LI->getType(), Offset);
488  continue;
489  }
490 
491  if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
492  // Storing the pointer, not into the value?
493  if (SI->getOperand(0) == V || !SI->isSimple()) return false;
494  // Don't touch MMX operations.
495  if (SI->getOperand(0)->getType()->isX86_MMXTy())
496  return false;
497  HadNonMemTransferAccess = true;
498  MergeInTypeForLoadOrStore(SI->getOperand(0)->getType(), Offset);
499  continue;
500  }
501 
502  if (BitCastInst *BCI = dyn_cast<BitCastInst>(UI)) {
503  if (!onlyUsedByLifetimeMarkers(BCI))
504  IsNotTrivial = true; // Can't be mem2reg'd.
505  if (!CanConvertToScalar(BCI, Offset, NonConstantIdx))
506  return false;
507  continue;
508  }
509 
510  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(UI)) {
511  // If this is a GEP with a variable indices, we can't handle it.
512  PointerType* PtrTy = dyn_cast<PointerType>(GEP->getPointerOperandType());
513  if (!PtrTy)
514  return false;
515 
516  // Compute the offset that this GEP adds to the pointer.
517  SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
518  Value *GEPNonConstantIdx = nullptr;
519  if (!GEP->hasAllConstantIndices()) {
520  if (!isa<VectorType>(PtrTy->getElementType()))
521  return false;
522  if (NonConstantIdx)
523  return false;
524  GEPNonConstantIdx = Indices.pop_back_val();
525  if (!GEPNonConstantIdx->getType()->isIntegerTy(32))
526  return false;
527  HadDynamicAccess = true;
528  } else
529  GEPNonConstantIdx = NonConstantIdx;
530  uint64_t GEPOffset = DL.getIndexedOffset(PtrTy,
531  Indices);
532  // See if all uses can be converted.
533  if (!CanConvertToScalar(GEP, Offset+GEPOffset, GEPNonConstantIdx))
534  return false;
535  IsNotTrivial = true; // Can't be mem2reg'd.
536  HadNonMemTransferAccess = true;
537  continue;
538  }
539 
540  // If this is a constant sized memset of a constant value (e.g. 0) we can
541  // handle it.
542  if (MemSetInst *MSI = dyn_cast<MemSetInst>(UI)) {
543  // Store to dynamic index.
544  if (NonConstantIdx)
545  return false;
546  // Store of constant value.
547  if (!isa<ConstantInt>(MSI->getValue()))
548  return false;
549 
550  // Store of constant size.
551  ConstantInt *Len = dyn_cast<ConstantInt>(MSI->getLength());
552  if (!Len)
553  return false;
554 
555  // If the size differs from the alloca, we can only convert the alloca to
556  // an integer bag-of-bits.
557  // FIXME: This should handle all of the cases that are currently accepted
558  // as vector element insertions.
559  if (Len->getZExtValue() != AllocaSize || Offset != 0)
560  ScalarKind = Integer;
561 
562  IsNotTrivial = true; // Can't be mem2reg'd.
563  HadNonMemTransferAccess = true;
564  continue;
565  }
566 
567  // If this is a memcpy or memmove into or out of the whole allocation, we
568  // can handle it like a load or store of the scalar type.
569  if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(UI)) {
570  // Store to dynamic index.
571  if (NonConstantIdx)
572  return false;
573  ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength());
574  if (!Len || Len->getZExtValue() != AllocaSize || Offset != 0)
575  return false;
576 
577  IsNotTrivial = true; // Can't be mem2reg'd.
578  continue;
579  }
580 
581  // If this is a lifetime intrinsic, we can handle it.
582  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(UI)) {
583  if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
584  II->getIntrinsicID() == Intrinsic::lifetime_end) {
585  continue;
586  }
587  }
588 
589  // Otherwise, we cannot handle this!
590  return false;
591  }
592 
593  return true;
594 }
595 
596 /// ConvertUsesToScalar - Convert all of the users of Ptr to use the new alloca
597 /// directly. This happens when we are converting an "integer union" to a
598 /// single integer scalar, or when we are converting a "vector union" to a
599 /// vector with insert/extractelement instructions.
600 ///
601 /// Offset is an offset from the original alloca, in bits that need to be
602 /// shifted to the right. By the end of this, there should be no uses of Ptr.
603 void ConvertToScalarInfo::ConvertUsesToScalar(Value *Ptr, AllocaInst *NewAI,
604  uint64_t Offset,
605  Value* NonConstantIdx) {
606  while (!Ptr->use_empty()) {
607  Instruction *User = cast<Instruction>(Ptr->user_back());
608 
609  if (BitCastInst *CI = dyn_cast<BitCastInst>(User)) {
610  ConvertUsesToScalar(CI, NewAI, Offset, NonConstantIdx);
611  CI->eraseFromParent();
612  continue;
613  }
614 
615  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(User)) {
616  // Compute the offset that this GEP adds to the pointer.
617  SmallVector<Value*, 8> Indices(GEP->op_begin()+1, GEP->op_end());
618  Value* GEPNonConstantIdx = nullptr;
619  if (!GEP->hasAllConstantIndices()) {
620  assert(!NonConstantIdx &&
621  "Dynamic GEP reading from dynamic GEP unsupported");
622  GEPNonConstantIdx = Indices.pop_back_val();
623  } else
624  GEPNonConstantIdx = NonConstantIdx;
625  uint64_t GEPOffset = DL.getIndexedOffset(GEP->getPointerOperandType(),
626  Indices);
627  ConvertUsesToScalar(GEP, NewAI, Offset+GEPOffset*8, GEPNonConstantIdx);
628  GEP->eraseFromParent();
629  continue;
630  }
631 
632  IRBuilder<> Builder(User);
633 
634  if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
635  // The load is a bit extract from NewAI shifted right by Offset bits.
636  Value *LoadedVal = Builder.CreateLoad(NewAI);
637  Value *NewLoadVal
638  = ConvertScalar_ExtractValue(LoadedVal, LI->getType(), Offset,
639  NonConstantIdx, Builder);
640  LI->replaceAllUsesWith(NewLoadVal);
641  LI->eraseFromParent();
642  continue;
643  }
644 
645  if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
646  assert(SI->getOperand(0) != Ptr && "Consistency error!");
647  Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
648  Value *New = ConvertScalar_InsertValue(SI->getOperand(0), Old, Offset,
649  NonConstantIdx, Builder);
650  Builder.CreateStore(New, NewAI);
651  SI->eraseFromParent();
652 
653  // If the load we just inserted is now dead, then the inserted store
654  // overwrote the entire thing.
655  if (Old->use_empty())
656  Old->eraseFromParent();
657  continue;
658  }
659 
660  // If this is a constant sized memset of a constant value (e.g. 0) we can
661  // transform it into a store of the expanded constant value.
662  if (MemSetInst *MSI = dyn_cast<MemSetInst>(User)) {
663  assert(MSI->getRawDest() == Ptr && "Consistency error!");
664  assert(!NonConstantIdx && "Cannot replace dynamic memset with insert");
665  int64_t SNumBytes = cast<ConstantInt>(MSI->getLength())->getSExtValue();
666  if (SNumBytes > 0 && (SNumBytes >> 32) == 0) {
667  unsigned NumBytes = static_cast<unsigned>(SNumBytes);
668  unsigned Val = cast<ConstantInt>(MSI->getValue())->getZExtValue();
669 
670  // Compute the value replicated the right number of times.
671  APInt APVal(NumBytes*8, Val);
672 
673  // Splat the value if non-zero.
674  if (Val)
675  for (unsigned i = 1; i != NumBytes; ++i)
676  APVal |= APVal << 8;
677 
678  Instruction *Old = Builder.CreateLoad(NewAI, NewAI->getName()+".in");
679  Value *New = ConvertScalar_InsertValue(
680  ConstantInt::get(User->getContext(), APVal),
681  Old, Offset, nullptr, Builder);
682  Builder.CreateStore(New, NewAI);
683 
684  // If the load we just inserted is now dead, then the memset overwrote
685  // the entire thing.
686  if (Old->use_empty())
687  Old->eraseFromParent();
688  }
689  MSI->eraseFromParent();
690  continue;
691  }
692 
693  // If this is a memcpy or memmove into or out of the whole allocation, we
694  // can handle it like a load or store of the scalar type.
695  if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(User)) {
696  assert(Offset == 0 && "must be store to start of alloca");
697  assert(!NonConstantIdx && "Cannot replace dynamic transfer with insert");
698 
699  // If the source and destination are both to the same alloca, then this is
700  // a noop copy-to-self, just delete it. Otherwise, emit a load and store
701  // as appropriate.
702  AllocaInst *OrigAI = cast<AllocaInst>(GetUnderlyingObject(Ptr, DL, 0));
703 
704  if (GetUnderlyingObject(MTI->getSource(), DL, 0) != OrigAI) {
705  // Dest must be OrigAI, change this to be a load from the original
706  // pointer (bitcasted), then a store to our new alloca.
707  assert(MTI->getRawDest() == Ptr && "Neither use is of pointer?");
708  Value *SrcPtr = MTI->getSource();
709  PointerType* SPTy = cast<PointerType>(SrcPtr->getType());
710  PointerType* AIPTy = cast<PointerType>(NewAI->getType());
711  if (SPTy->getAddressSpace() != AIPTy->getAddressSpace()) {
712  AIPTy = PointerType::get(AIPTy->getElementType(),
713  SPTy->getAddressSpace());
714  }
715  SrcPtr = Builder.CreateBitCast(SrcPtr, AIPTy);
716 
717  LoadInst *SrcVal = Builder.CreateLoad(SrcPtr, "srcval");
718  SrcVal->setAlignment(MTI->getAlignment());
719  Builder.CreateStore(SrcVal, NewAI);
720  } else if (GetUnderlyingObject(MTI->getDest(), DL, 0) != OrigAI) {
721  // Src must be OrigAI, change this to be a load from NewAI then a store
722  // through the original dest pointer (bitcasted).
723  assert(MTI->getRawSource() == Ptr && "Neither use is of pointer?");
724  LoadInst *SrcVal = Builder.CreateLoad(NewAI, "srcval");
725 
726  PointerType* DPTy = cast<PointerType>(MTI->getDest()->getType());
727  PointerType* AIPTy = cast<PointerType>(NewAI->getType());
728  if (DPTy->getAddressSpace() != AIPTy->getAddressSpace()) {
729  AIPTy = PointerType::get(AIPTy->getElementType(),
730  DPTy->getAddressSpace());
731  }
732  Value *DstPtr = Builder.CreateBitCast(MTI->getDest(), AIPTy);
733 
734  StoreInst *NewStore = Builder.CreateStore(SrcVal, DstPtr);
735  NewStore->setAlignment(MTI->getAlignment());
736  } else {
737  // Noop transfer. Src == Dst
738  }
739 
740  MTI->eraseFromParent();
741  continue;
742  }
743 
744  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(User)) {
745  if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
746  II->getIntrinsicID() == Intrinsic::lifetime_end) {
747  // There's no need to preserve these, as the resulting alloca will be
748  // converted to a register anyways.
749  II->eraseFromParent();
750  continue;
751  }
752  }
753 
754  llvm_unreachable("Unsupported operation!");
755  }
756 }
757 
758 /// ConvertScalar_ExtractValue - Extract a value of type ToType from an integer
759 /// or vector value FromVal, extracting the bits from the offset specified by
760 /// Offset. This returns the value, which is of type ToType.
761 ///
762 /// This happens when we are converting an "integer union" to a single
763 /// integer scalar, or when we are converting a "vector union" to a vector with
764 /// insert/extractelement instructions.
765 ///
766 /// Offset is an offset from the original alloca, in bits that need to be
767 /// shifted to the right.
768 Value *ConvertToScalarInfo::
769 ConvertScalar_ExtractValue(Value *FromVal, Type *ToType,
770  uint64_t Offset, Value* NonConstantIdx,
771  IRBuilder<> &Builder) {
772  // If the load is of the whole new alloca, no conversion is needed.
773  Type *FromType = FromVal->getType();
774  if (FromType == ToType && Offset == 0)
775  return FromVal;
776 
777  // If the result alloca is a vector type, this is either an element
778  // access or a bitcast to another vector type of the same size.
779  if (VectorType *VTy = dyn_cast<VectorType>(FromType)) {
780  unsigned FromTypeSize = DL.getTypeAllocSize(FromType);
781  unsigned ToTypeSize = DL.getTypeAllocSize(ToType);
782  if (FromTypeSize == ToTypeSize)
783  return Builder.CreateBitCast(FromVal, ToType);
784 
785  // Otherwise it must be an element access.
786  unsigned Elt = 0;
787  if (Offset) {
788  unsigned EltSize = DL.getTypeAllocSizeInBits(VTy->getElementType());
789  Elt = Offset/EltSize;
790  assert(EltSize*Elt == Offset && "Invalid modulus in validity checking");
791  }
792  // Return the element extracted out of it.
793  Value *Idx;
794  if (NonConstantIdx) {
795  if (Elt)
796  Idx = Builder.CreateAdd(NonConstantIdx,
797  Builder.getInt32(Elt),
798  "dyn.offset");
799  else
800  Idx = NonConstantIdx;
801  } else
802  Idx = Builder.getInt32(Elt);
803  Value *V = Builder.CreateExtractElement(FromVal, Idx);
804  if (V->getType() != ToType)
805  V = Builder.CreateBitCast(V, ToType);
806  return V;
807  }
808 
809  // If ToType is a first class aggregate, extract out each of the pieces and
810  // use insertvalue's to form the FCA.
811  if (StructType *ST = dyn_cast<StructType>(ToType)) {
812  assert(!NonConstantIdx &&
813  "Dynamic indexing into struct types not supported");
814  const StructLayout &Layout = *DL.getStructLayout(ST);
815  Value *Res = UndefValue::get(ST);
816  for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
817  Value *Elt = ConvertScalar_ExtractValue(FromVal, ST->getElementType(i),
818  Offset+Layout.getElementOffsetInBits(i),
819  nullptr, Builder);
820  Res = Builder.CreateInsertValue(Res, Elt, i);
821  }
822  return Res;
823  }
824 
825  if (ArrayType *AT = dyn_cast<ArrayType>(ToType)) {
826  assert(!NonConstantIdx &&
827  "Dynamic indexing into array types not supported");
828  uint64_t EltSize = DL.getTypeAllocSizeInBits(AT->getElementType());
829  Value *Res = UndefValue::get(AT);
830  for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
831  Value *Elt = ConvertScalar_ExtractValue(FromVal, AT->getElementType(),
832  Offset+i*EltSize, nullptr,
833  Builder);
834  Res = Builder.CreateInsertValue(Res, Elt, i);
835  }
836  return Res;
837  }
838 
839  // Otherwise, this must be a union that was converted to an integer value.
840  IntegerType *NTy = cast<IntegerType>(FromVal->getType());
841 
842  // If this is a big-endian system and the load is narrower than the
843  // full alloca type, we need to do a shift to get the right bits.
844  int ShAmt = 0;
845  if (DL.isBigEndian()) {
846  // On big-endian machines, the lowest bit is stored at the bit offset
847  // from the pointer given by getTypeStoreSizeInBits. This matters for
848  // integers with a bitwidth that is not a multiple of 8.
849  ShAmt = DL.getTypeStoreSizeInBits(NTy) -
850  DL.getTypeStoreSizeInBits(ToType) - Offset;
851  } else {
852  ShAmt = Offset;
853  }
854 
855  // Note: we support negative bitwidths (with shl) which are not defined.
856  // We do this to support (f.e.) loads off the end of a structure where
857  // only some bits are used.
858  if (ShAmt > 0 && (unsigned)ShAmt < NTy->getBitWidth())
859  FromVal = Builder.CreateLShr(FromVal,
860  ConstantInt::get(FromVal->getType(), ShAmt));
861  else if (ShAmt < 0 && (unsigned)-ShAmt < NTy->getBitWidth())
862  FromVal = Builder.CreateShl(FromVal,
863  ConstantInt::get(FromVal->getType(), -ShAmt));
864 
865  // Finally, unconditionally truncate the integer to the right width.
866  unsigned LIBitWidth = DL.getTypeSizeInBits(ToType);
867  if (LIBitWidth < NTy->getBitWidth())
868  FromVal =
869  Builder.CreateTrunc(FromVal, IntegerType::get(FromVal->getContext(),
870  LIBitWidth));
871  else if (LIBitWidth > NTy->getBitWidth())
872  FromVal =
873  Builder.CreateZExt(FromVal, IntegerType::get(FromVal->getContext(),
874  LIBitWidth));
875 
876  // If the result is an integer, this is a trunc or bitcast.
877  if (ToType->isIntegerTy()) {
878  // Should be done.
879  } else if (ToType->isFloatingPointTy() || ToType->isVectorTy()) {
880  // Just do a bitcast, we know the sizes match up.
881  FromVal = Builder.CreateBitCast(FromVal, ToType);
882  } else {
883  // Otherwise must be a pointer.
884  FromVal = Builder.CreateIntToPtr(FromVal, ToType);
885  }
886  assert(FromVal->getType() == ToType && "Didn't convert right?");
887  return FromVal;
888 }
889 
890 /// ConvertScalar_InsertValue - Insert the value "SV" into the existing integer
891 /// or vector value "Old" at the offset specified by Offset.
892 ///
893 /// This happens when we are converting an "integer union" to a
894 /// single integer scalar, or when we are converting a "vector union" to a
895 /// vector with insert/extractelement instructions.
896 ///
897 /// Offset is an offset from the original alloca, in bits that need to be
898 /// shifted to the right.
899 ///
900 /// NonConstantIdx is an index value if there was a GEP with a non-constant
901 /// index value. If this is 0 then all GEPs used to find this insert address
902 /// are constant.
903 Value *ConvertToScalarInfo::
904 ConvertScalar_InsertValue(Value *SV, Value *Old,
905  uint64_t Offset, Value* NonConstantIdx,
906  IRBuilder<> &Builder) {
907  // Convert the stored type to the actual type, shift it left to insert
908  // then 'or' into place.
909  Type *AllocaType = Old->getType();
910  LLVMContext &Context = Old->getContext();
911 
912  if (VectorType *VTy = dyn_cast<VectorType>(AllocaType)) {
913  uint64_t VecSize = DL.getTypeAllocSizeInBits(VTy);
914  uint64_t ValSize = DL.getTypeAllocSizeInBits(SV->getType());
915 
916  // Changing the whole vector with memset or with an access of a different
917  // vector type?
918  if (ValSize == VecSize)
919  return Builder.CreateBitCast(SV, AllocaType);
920 
921  // Must be an element insertion.
922  Type *EltTy = VTy->getElementType();
923  if (SV->getType() != EltTy)
924  SV = Builder.CreateBitCast(SV, EltTy);
925  uint64_t EltSize = DL.getTypeAllocSizeInBits(EltTy);
926  unsigned Elt = Offset/EltSize;
927  Value *Idx;
928  if (NonConstantIdx) {
929  if (Elt)
930  Idx = Builder.CreateAdd(NonConstantIdx,
931  Builder.getInt32(Elt),
932  "dyn.offset");
933  else
934  Idx = NonConstantIdx;
935  } else
936  Idx = Builder.getInt32(Elt);
937  return Builder.CreateInsertElement(Old, SV, Idx);
938  }
939 
940  // If SV is a first-class aggregate value, insert each value recursively.
941  if (StructType *ST = dyn_cast<StructType>(SV->getType())) {
942  assert(!NonConstantIdx &&
943  "Dynamic indexing into struct types not supported");
944  const StructLayout &Layout = *DL.getStructLayout(ST);
945  for (unsigned i = 0, e = ST->getNumElements(); i != e; ++i) {
946  Value *Elt = Builder.CreateExtractValue(SV, i);
947  Old = ConvertScalar_InsertValue(Elt, Old,
948  Offset+Layout.getElementOffsetInBits(i),
949  nullptr, Builder);
950  }
951  return Old;
952  }
953 
954  if (ArrayType *AT = dyn_cast<ArrayType>(SV->getType())) {
955  assert(!NonConstantIdx &&
956  "Dynamic indexing into array types not supported");
957  uint64_t EltSize = DL.getTypeAllocSizeInBits(AT->getElementType());
958  for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
959  Value *Elt = Builder.CreateExtractValue(SV, i);
960  Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, nullptr,
961  Builder);
962  }
963  return Old;
964  }
965 
966  // If SV is a float, convert it to the appropriate integer type.
967  // If it is a pointer, do the same.
968  unsigned SrcWidth = DL.getTypeSizeInBits(SV->getType());
969  unsigned DestWidth = DL.getTypeSizeInBits(AllocaType);
970  unsigned SrcStoreWidth = DL.getTypeStoreSizeInBits(SV->getType());
971  unsigned DestStoreWidth = DL.getTypeStoreSizeInBits(AllocaType);
972  if (SV->getType()->isFloatingPointTy() || SV->getType()->isVectorTy())
973  SV = Builder.CreateBitCast(SV, IntegerType::get(SV->getContext(),SrcWidth));
974  else if (SV->getType()->isPointerTy())
975  SV = Builder.CreatePtrToInt(SV, DL.getIntPtrType(SV->getType()));
976 
977  // Zero extend or truncate the value if needed.
978  if (SV->getType() != AllocaType) {
979  if (SV->getType()->getPrimitiveSizeInBits() <
980  AllocaType->getPrimitiveSizeInBits())
981  SV = Builder.CreateZExt(SV, AllocaType);
982  else {
983  // Truncation may be needed if storing more than the alloca can hold
984  // (undefined behavior).
985  SV = Builder.CreateTrunc(SV, AllocaType);
986  SrcWidth = DestWidth;
987  SrcStoreWidth = DestStoreWidth;
988  }
989  }
990 
991  // If this is a big-endian system and the store is narrower than the
992  // full alloca type, we need to do a shift to get the right bits.
993  int ShAmt = 0;
994  if (DL.isBigEndian()) {
995  // On big-endian machines, the lowest bit is stored at the bit offset
996  // from the pointer given by getTypeStoreSizeInBits. This matters for
997  // integers with a bitwidth that is not a multiple of 8.
998  ShAmt = DestStoreWidth - SrcStoreWidth - Offset;
999  } else {
1000  ShAmt = Offset;
1001  }
1002 
1003  // Note: we support negative bitwidths (with shr) which are not defined.
1004  // We do this to support (f.e.) stores off the end of a structure where
1005  // only some bits in the structure are set.
1006  APInt Mask(APInt::getLowBitsSet(DestWidth, SrcWidth));
1007  if (ShAmt > 0 && (unsigned)ShAmt < DestWidth) {
1008  SV = Builder.CreateShl(SV, ConstantInt::get(SV->getType(), ShAmt));
1009  Mask <<= ShAmt;
1010  } else if (ShAmt < 0 && (unsigned)-ShAmt < DestWidth) {
1011  SV = Builder.CreateLShr(SV, ConstantInt::get(SV->getType(), -ShAmt));
1012  Mask = Mask.lshr(-ShAmt);
1013  }
1014 
1015  // Mask out the bits we are about to insert from the old value, and or
1016  // in the new bits.
1017  if (SrcWidth != DestWidth) {
1018  assert(DestWidth > SrcWidth);
1019  Old = Builder.CreateAnd(Old, ConstantInt::get(Context, ~Mask), "mask");
1020  SV = Builder.CreateOr(Old, SV, "ins");
1021  }
1022  return SV;
1023 }
1024 
1025 
1026 //===----------------------------------------------------------------------===//
1027 // SRoA Driver
1028 //===----------------------------------------------------------------------===//
1029 
1030 
1031 bool SROA::runOnFunction(Function &F) {
1032  if (skipOptnoneFunction(F))
1033  return false;
1034 
1035  bool Changed = performPromotion(F);
1036 
1037  while (1) {
1038  bool LocalChange = performScalarRepl(F);
1039  if (!LocalChange) break; // No need to repromote if no scalarrepl
1040  Changed = true;
1041  LocalChange = performPromotion(F);
1042  if (!LocalChange) break; // No need to re-scalarrepl if no promotion
1043  }
1044 
1045  return Changed;
1046 }
1047 
1048 namespace {
1049 class AllocaPromoter : public LoadAndStorePromoter {
1050  AllocaInst *AI;
1051  DIBuilder *DIB;
1054 public:
1055  AllocaPromoter(ArrayRef<Instruction*> Insts, SSAUpdater &S,
1056  DIBuilder *DB)
1057  : LoadAndStorePromoter(Insts, S), AI(nullptr), DIB(DB) {}
1058 
1059  void run(AllocaInst *AI, const SmallVectorImpl<Instruction*> &Insts) {
1060  // Remember which alloca we're promoting (for isInstInList).
1061  this->AI = AI;
1062  if (auto *L = LocalAsMetadata::getIfExists(AI)) {
1063  if (auto *DINode = MetadataAsValue::getIfExists(AI->getContext(), L)) {
1064  for (User *U : DINode->users())
1065  if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(U))
1066  DDIs.push_back(DDI);
1067  else if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(U))
1068  DVIs.push_back(DVI);
1069  }
1070  }
1071 
1073  AI->eraseFromParent();
1074  for (SmallVectorImpl<DbgDeclareInst *>::iterator I = DDIs.begin(),
1075  E = DDIs.end(); I != E; ++I) {
1076  DbgDeclareInst *DDI = *I;
1077  DDI->eraseFromParent();
1078  }
1079  for (SmallVectorImpl<DbgValueInst *>::iterator I = DVIs.begin(),
1080  E = DVIs.end(); I != E; ++I) {
1081  DbgValueInst *DVI = *I;
1082  DVI->eraseFromParent();
1083  }
1084  }
1085 
1086  bool isInstInList(Instruction *I,
1087  const SmallVectorImpl<Instruction*> &Insts) const override {
1088  if (LoadInst *LI = dyn_cast<LoadInst>(I))
1089  return LI->getOperand(0) == AI;
1090  return cast<StoreInst>(I)->getPointerOperand() == AI;
1091  }
1092 
1093  void updateDebugInfo(Instruction *Inst) const override {
1095  E = DDIs.end(); I != E; ++I) {
1096  DbgDeclareInst *DDI = *I;
1097  if (StoreInst *SI = dyn_cast<StoreInst>(Inst))
1098  ConvertDebugDeclareToDebugValue(DDI, SI, *DIB);
1099  else if (LoadInst *LI = dyn_cast<LoadInst>(Inst))
1100  ConvertDebugDeclareToDebugValue(DDI, LI, *DIB);
1101  }
1103  E = DVIs.end(); I != E; ++I) {
1104  DbgValueInst *DVI = *I;
1105  Value *Arg = nullptr;
1106  if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
1107  // If an argument is zero extended then use argument directly. The ZExt
1108  // may be zapped by an optimization pass in future.
1109  if (ZExtInst *ZExt = dyn_cast<ZExtInst>(SI->getOperand(0)))
1110  Arg = dyn_cast<Argument>(ZExt->getOperand(0));
1111  if (SExtInst *SExt = dyn_cast<SExtInst>(SI->getOperand(0)))
1112  Arg = dyn_cast<Argument>(SExt->getOperand(0));
1113  if (!Arg)
1114  Arg = SI->getOperand(0);
1115  } else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
1116  Arg = LI->getOperand(0);
1117  } else {
1118  continue;
1119  }
1120  DIB->insertDbgValueIntrinsic(Arg, 0, DVI->getVariable(),
1121  DVI->getExpression(), DVI->getDebugLoc(),
1122  Inst);
1123  }
1124  }
1125 };
1126 } // end anon namespace
1127 
1128 /// isSafeSelectToSpeculate - Select instructions that use an alloca and are
1129 /// subsequently loaded can be rewritten to load both input pointers and then
1130 /// select between the result, allowing the load of the alloca to be promoted.
1131 /// From this:
1132 /// %P2 = select i1 %cond, i32* %Alloca, i32* %Other
1133 /// %V = load i32* %P2
1134 /// to:
1135 /// %V1 = load i32* %Alloca -> will be mem2reg'd
1136 /// %V2 = load i32* %Other
1137 /// %V = select i1 %cond, i32 %V1, i32 %V2
1138 ///
1139 /// We can do this to a select if its only uses are loads and if the operand to
1140 /// the select can be loaded unconditionally.
1142  const DataLayout &DL = SI->getModule()->getDataLayout();
1143  bool TDerefable = isDereferenceablePointer(SI->getTrueValue(), DL);
1144  bool FDerefable = isDereferenceablePointer(SI->getFalseValue(), DL);
1145 
1146  for (User *U : SI->users()) {
1147  LoadInst *LI = dyn_cast<LoadInst>(U);
1148  if (!LI || !LI->isSimple()) return false;
1149 
1150  // Both operands to the select need to be dereferencable, either absolutely
1151  // (e.g. allocas) or at this point because we can see other accesses to it.
1152  if (!TDerefable &&
1154  LI->getAlignment()))
1155  return false;
1156  if (!FDerefable &&
1158  LI->getAlignment()))
1159  return false;
1160  }
1161 
1162  return true;
1163 }
1164 
1165 /// isSafePHIToSpeculate - PHI instructions that use an alloca and are
1166 /// subsequently loaded can be rewritten to load both input pointers in the pred
1167 /// blocks and then PHI the results, allowing the load of the alloca to be
1168 /// promoted.
1169 /// From this:
1170 /// %P2 = phi [i32* %Alloca, i32* %Other]
1171 /// %V = load i32* %P2
1172 /// to:
1173 /// %V1 = load i32* %Alloca -> will be mem2reg'd
1174 /// ...
1175 /// %V2 = load i32* %Other
1176 /// ...
1177 /// %V = phi [i32 %V1, i32 %V2]
1178 ///
1179 /// We can do this to a select if its only uses are loads and if the operand to
1180 /// the select can be loaded unconditionally.
1181 static bool isSafePHIToSpeculate(PHINode *PN) {
1182  // For now, we can only do this promotion if the load is in the same block as
1183  // the PHI, and if there are no stores between the phi and load.
1184  // TODO: Allow recursive phi users.
1185  // TODO: Allow stores.
1186  BasicBlock *BB = PN->getParent();
1187  unsigned MaxAlign = 0;
1188  for (User *U : PN->users()) {
1189  LoadInst *LI = dyn_cast<LoadInst>(U);
1190  if (!LI || !LI->isSimple()) return false;
1191 
1192  // For now we only allow loads in the same block as the PHI. This is a
1193  // common case that happens when instcombine merges two loads through a PHI.
1194  if (LI->getParent() != BB) return false;
1195 
1196  // Ensure that there are no instructions between the PHI and the load that
1197  // could store.
1198  for (BasicBlock::iterator BBI = PN; &*BBI != LI; ++BBI)
1199  if (BBI->mayWriteToMemory())
1200  return false;
1201 
1202  MaxAlign = std::max(MaxAlign, LI->getAlignment());
1203  }
1204 
1205  const DataLayout &DL = PN->getModule()->getDataLayout();
1206 
1207  // Okay, we know that we have one or more loads in the same block as the PHI.
1208  // We can transform this if it is safe to push the loads into the predecessor
1209  // blocks. The only thing to watch out for is that we can't put a possibly
1210  // trapping load in the predecessor if it is a critical edge.
1211  for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1212  BasicBlock *Pred = PN->getIncomingBlock(i);
1213  Value *InVal = PN->getIncomingValue(i);
1214 
1215  // If the terminator of the predecessor has side-effects (an invoke),
1216  // there is no safe place to put a load in the predecessor.
1217  if (Pred->getTerminator()->mayHaveSideEffects())
1218  return false;
1219 
1220  // If the value is produced by the terminator of the predecessor
1221  // (an invoke), there is no valid place to put a load in the predecessor.
1222  if (Pred->getTerminator() == InVal)
1223  return false;
1224 
1225  // If the predecessor has a single successor, then the edge isn't critical.
1226  if (Pred->getTerminator()->getNumSuccessors() == 1)
1227  continue;
1228 
1229  // If this pointer is always safe to load, or if we can prove that there is
1230  // already a load in the block, then we can move the load to the pred block.
1231  if (isDereferenceablePointer(InVal, DL) ||
1232  isSafeToLoadUnconditionally(InVal, Pred->getTerminator(), MaxAlign))
1233  continue;
1234 
1235  return false;
1236  }
1237 
1238  return true;
1239 }
1240 
1241 
1242 /// tryToMakeAllocaBePromotable - This returns true if the alloca only has
1243 /// direct (non-volatile) loads and stores to it. If the alloca is close but
1244 /// not quite there, this will transform the code to allow promotion. As such,
1245 /// it is a non-pure predicate.
1248  SmallPtrSet<Instruction*, 4> > InstsToRewrite;
1249  for (User *U : AI->users()) {
1250  if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
1251  if (!LI->isSimple())
1252  return false;
1253  continue;
1254  }
1255 
1256  if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
1257  if (SI->getOperand(0) == AI || !SI->isSimple())
1258  return false; // Don't allow a store OF the AI, only INTO the AI.
1259  continue;
1260  }
1261 
1262  if (SelectInst *SI = dyn_cast<SelectInst>(U)) {
1263  // If the condition being selected on is a constant, fold the select, yes
1264  // this does (rarely) happen early on.
1265  if (ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition())) {
1266  Value *Result = SI->getOperand(1+CI->isZero());
1267  SI->replaceAllUsesWith(Result);
1268  SI->eraseFromParent();
1269 
1270  // This is very rare and we just scrambled the use list of AI, start
1271  // over completely.
1272  return tryToMakeAllocaBePromotable(AI, DL);
1273  }
1274 
1275  // If it is safe to turn "load (select c, AI, ptr)" into a select of two
1276  // loads, then we can transform this by rewriting the select.
1278  return false;
1279 
1280  InstsToRewrite.insert(SI);
1281  continue;
1282  }
1283 
1284  if (PHINode *PN = dyn_cast<PHINode>(U)) {
1285  if (PN->use_empty()) { // Dead PHIs can be stripped.
1286  InstsToRewrite.insert(PN);
1287  continue;
1288  }
1289 
1290  // If it is safe to turn "load (phi [AI, ptr, ...])" into a PHI of loads
1291  // in the pred blocks, then we can transform this by rewriting the PHI.
1292  if (!isSafePHIToSpeculate(PN))
1293  return false;
1294 
1295  InstsToRewrite.insert(PN);
1296  continue;
1297  }
1298 
1299  if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) {
1300  if (onlyUsedByLifetimeMarkers(BCI)) {
1301  InstsToRewrite.insert(BCI);
1302  continue;
1303  }
1304  }
1305 
1306  return false;
1307  }
1308 
1309  // If there are no instructions to rewrite, then all uses are load/stores and
1310  // we're done!
1311  if (InstsToRewrite.empty())
1312  return true;
1313 
1314  // If we have instructions that need to be rewritten for this to be promotable
1315  // take care of it now.
1316  for (unsigned i = 0, e = InstsToRewrite.size(); i != e; ++i) {
1317  if (BitCastInst *BCI = dyn_cast<BitCastInst>(InstsToRewrite[i])) {
1318  // This could only be a bitcast used by nothing but lifetime intrinsics.
1319  for (BitCastInst::user_iterator I = BCI->user_begin(), E = BCI->user_end();
1320  I != E;)
1321  cast<Instruction>(*I++)->eraseFromParent();
1322  BCI->eraseFromParent();
1323  continue;
1324  }
1325 
1326  if (SelectInst *SI = dyn_cast<SelectInst>(InstsToRewrite[i])) {
1327  // Selects in InstsToRewrite only have load uses. Rewrite each as two
1328  // loads with a new select.
1329  while (!SI->use_empty()) {
1330  LoadInst *LI = cast<LoadInst>(SI->user_back());
1331 
1332  IRBuilder<> Builder(LI);
1333  LoadInst *TrueLoad =
1334  Builder.CreateLoad(SI->getTrueValue(), LI->getName()+".t");
1335  LoadInst *FalseLoad =
1336  Builder.CreateLoad(SI->getFalseValue(), LI->getName()+".f");
1337 
1338  // Transfer alignment and AA info if present.
1339  TrueLoad->setAlignment(LI->getAlignment());
1340  FalseLoad->setAlignment(LI->getAlignment());
1341 
1342  AAMDNodes Tags;
1343  LI->getAAMetadata(Tags);
1344  if (Tags) {
1345  TrueLoad->setAAMetadata(Tags);
1346  FalseLoad->setAAMetadata(Tags);
1347  }
1348 
1349  Value *V = Builder.CreateSelect(SI->getCondition(), TrueLoad, FalseLoad);
1350  V->takeName(LI);
1351  LI->replaceAllUsesWith(V);
1352  LI->eraseFromParent();
1353  }
1354 
1355  // Now that all the loads are gone, the select is gone too.
1356  SI->eraseFromParent();
1357  continue;
1358  }
1359 
1360  // Otherwise, we have a PHI node which allows us to push the loads into the
1361  // predecessors.
1362  PHINode *PN = cast<PHINode>(InstsToRewrite[i]);
1363  if (PN->use_empty()) {
1364  PN->eraseFromParent();
1365  continue;
1366  }
1367 
1368  Type *LoadTy = cast<PointerType>(PN->getType())->getElementType();
1369  PHINode *NewPN = PHINode::Create(LoadTy, PN->getNumIncomingValues(),
1370  PN->getName()+".ld", PN);
1371 
1372  // Get the AA tags and alignment to use from one of the loads. It doesn't
1373  // matter which one we get and if any differ, it doesn't matter.
1374  LoadInst *SomeLoad = cast<LoadInst>(PN->user_back());
1375 
1376  AAMDNodes AATags;
1377  SomeLoad->getAAMetadata(AATags);
1378  unsigned Align = SomeLoad->getAlignment();
1379 
1380  // Rewrite all loads of the PN to use the new PHI.
1381  while (!PN->use_empty()) {
1382  LoadInst *LI = cast<LoadInst>(PN->user_back());
1383  LI->replaceAllUsesWith(NewPN);
1384  LI->eraseFromParent();
1385  }
1386 
1387  // Inject loads into all of the pred blocks. Keep track of which blocks we
1388  // insert them into in case we have multiple edges from the same block.
1389  DenseMap<BasicBlock*, LoadInst*> InsertedLoads;
1390 
1391  for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1392  BasicBlock *Pred = PN->getIncomingBlock(i);
1393  LoadInst *&Load = InsertedLoads[Pred];
1394  if (!Load) {
1395  Load = new LoadInst(PN->getIncomingValue(i),
1396  PN->getName() + "." + Pred->getName(),
1397  Pred->getTerminator());
1398  Load->setAlignment(Align);
1399  if (AATags) Load->setAAMetadata(AATags);
1400  }
1401 
1402  NewPN->addIncoming(Load, Pred);
1403  }
1404 
1405  PN->eraseFromParent();
1406  }
1407 
1408  ++NumAdjusted;
1409  return true;
1410 }
1411 
1412 bool SROA::performPromotion(Function &F) {
1413  std::vector<AllocaInst*> Allocas;
1414  const DataLayout &DL = F.getParent()->getDataLayout();
1415  DominatorTree *DT = nullptr;
1416  if (HasDomTree)
1417  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1418  AssumptionCache &AC =
1419  getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
1420 
1421  BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function
1422  DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false);
1423  bool Changed = false;
1425  while (1) {
1426  Allocas.clear();
1427 
1428  // Find allocas that are safe to promote, by looking at all instructions in
1429  // the entry node
1430  for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I)
1431  if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca?
1432  if (tryToMakeAllocaBePromotable(AI, DL))
1433  Allocas.push_back(AI);
1434 
1435  if (Allocas.empty()) break;
1436 
1437  if (HasDomTree)
1438  PromoteMemToReg(Allocas, *DT, nullptr, &AC);
1439  else {
1440  SSAUpdater SSA;
1441  for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
1442  AllocaInst *AI = Allocas[i];
1443 
1444  // Build list of instructions to promote.
1445  for (User *U : AI->users())
1446  Insts.push_back(cast<Instruction>(U));
1447  AllocaPromoter(Insts, SSA, &DIB).run(AI, Insts);
1448  Insts.clear();
1449  }
1450  }
1451  NumPromoted += Allocas.size();
1452  Changed = true;
1453  }
1454 
1455  return Changed;
1456 }
1457 
1458 
1459 /// ShouldAttemptScalarRepl - Decide if an alloca is a good candidate for
1460 /// SROA. It must be a struct or array type with a small number of elements.
1461 bool SROA::ShouldAttemptScalarRepl(AllocaInst *AI) {
1462  Type *T = AI->getAllocatedType();
1463  // Do not promote any struct that has too many members.
1464  if (StructType *ST = dyn_cast<StructType>(T))
1465  return ST->getNumElements() <= StructMemberThreshold;
1466  // Do not promote any array that has too many elements.
1467  if (ArrayType *AT = dyn_cast<ArrayType>(T))
1468  return AT->getNumElements() <= ArrayElementThreshold;
1469  return false;
1470 }
1471 
1472 // performScalarRepl - This algorithm is a simple worklist driven algorithm,
1473 // which runs on all of the alloca instructions in the entry block, removing
1474 // them if they are only used by getelementptr instructions.
1475 //
1476 bool SROA::performScalarRepl(Function &F) {
1477  std::vector<AllocaInst*> WorkList;
1478  const DataLayout &DL = F.getParent()->getDataLayout();
1479 
1480  // Scan the entry basic block, adding allocas to the worklist.
1481  BasicBlock &BB = F.getEntryBlock();
1482  for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I)
1483  if (AllocaInst *A = dyn_cast<AllocaInst>(I))
1484  WorkList.push_back(A);
1485 
1486  // Process the worklist
1487  bool Changed = false;
1488  while (!WorkList.empty()) {
1489  AllocaInst *AI = WorkList.back();
1490  WorkList.pop_back();
1491 
1492  // Handle dead allocas trivially. These can be formed by SROA'ing arrays
1493  // with unused elements.
1494  if (AI->use_empty()) {
1495  AI->eraseFromParent();
1496  Changed = true;
1497  continue;
1498  }
1499 
1500  // If this alloca is impossible for us to promote, reject it early.
1501  if (AI->isArrayAllocation() || !AI->getAllocatedType()->isSized())
1502  continue;
1503 
1504  // Check to see if we can perform the core SROA transformation. We cannot
1505  // transform the allocation instruction if it is an array allocation
1506  // (allocations OF arrays are ok though), and an allocation of a scalar
1507  // value cannot be decomposed at all.
1508  uint64_t AllocaSize = DL.getTypeAllocSize(AI->getAllocatedType());
1509 
1510  // Do not promote [0 x %struct].
1511  if (AllocaSize == 0) continue;
1512 
1513  // Do not promote any struct whose size is too big.
1514  if (AllocaSize > SRThreshold) continue;
1515 
1516  // If the alloca looks like a good candidate for scalar replacement, and if
1517  // all its users can be transformed, then split up the aggregate into its
1518  // separate elements.
1519  if (ShouldAttemptScalarRepl(AI) && isSafeAllocaToScalarRepl(AI)) {
1520  DoScalarReplacement(AI, WorkList);
1521  Changed = true;
1522  continue;
1523  }
1524 
1525  // If we can turn this aggregate value (potentially with casts) into a
1526  // simple scalar value that can be mem2reg'd into a register value.
1527  // IsNotTrivial tracks whether this is something that mem2reg could have
1528  // promoted itself. If so, we don't want to transform it needlessly. Note
1529  // that we can't just check based on the type: the alloca may be of an i32
1530  // but that has pointer arithmetic to set byte 3 of it or something.
1531  if (AllocaInst *NewAI =
1532  ConvertToScalarInfo((unsigned)AllocaSize, DL, ScalarLoadThreshold)
1533  .TryConvert(AI)) {
1534  NewAI->takeName(AI);
1535  AI->eraseFromParent();
1536  ++NumConverted;
1537  Changed = true;
1538  continue;
1539  }
1540 
1541  // Otherwise, couldn't process this alloca.
1542  }
1543 
1544  return Changed;
1545 }
1546 
1547 /// DoScalarReplacement - This alloca satisfied the isSafeAllocaToScalarRepl
1548 /// predicate, do SROA now.
1549 void SROA::DoScalarReplacement(AllocaInst *AI,
1550  std::vector<AllocaInst*> &WorkList) {
1551  DEBUG(dbgs() << "Found inst to SROA: " << *AI << '\n');
1552  SmallVector<AllocaInst*, 32> ElementAllocas;
1553  if (StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
1554  ElementAllocas.reserve(ST->getNumContainedTypes());
1555  for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) {
1556  AllocaInst *NA = new AllocaInst(ST->getContainedType(i), nullptr,
1557  AI->getAlignment(),
1558  AI->getName() + "." + Twine(i), AI);
1559  ElementAllocas.push_back(NA);
1560  WorkList.push_back(NA); // Add to worklist for recursive processing
1561  }
1562  } else {
1563  ArrayType *AT = cast<ArrayType>(AI->getAllocatedType());
1564  ElementAllocas.reserve(AT->getNumElements());
1565  Type *ElTy = AT->getElementType();
1566  for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) {
1567  AllocaInst *NA = new AllocaInst(ElTy, nullptr, AI->getAlignment(),
1568  AI->getName() + "." + Twine(i), AI);
1569  ElementAllocas.push_back(NA);
1570  WorkList.push_back(NA); // Add to worklist for recursive processing
1571  }
1572  }
1573 
1574  // Now that we have created the new alloca instructions, rewrite all the
1575  // uses of the old alloca.
1576  RewriteForScalarRepl(AI, AI, 0, ElementAllocas);
1577 
1578  // Now erase any instructions that were made dead while rewriting the alloca.
1579  DeleteDeadInstructions();
1580  AI->eraseFromParent();
1581 
1582  ++NumReplaced;
1583 }
1584 
1585 /// DeleteDeadInstructions - Erase instructions on the DeadInstrs list,
1586 /// recursively including all their operands that become trivially dead.
1587 void SROA::DeleteDeadInstructions() {
1588  while (!DeadInsts.empty()) {
1589  Instruction *I = cast<Instruction>(DeadInsts.pop_back_val());
1590 
1591  for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI)
1592  if (Instruction *U = dyn_cast<Instruction>(*OI)) {
1593  // Zero out the operand and see if it becomes trivially dead.
1594  // (But, don't add allocas to the dead instruction list -- they are
1595  // already on the worklist and will be deleted separately.)
1596  *OI = nullptr;
1597  if (isInstructionTriviallyDead(U) && !isa<AllocaInst>(U))
1598  DeadInsts.push_back(U);
1599  }
1600 
1601  I->eraseFromParent();
1602  }
1603 }
1604 
1605 /// isSafeForScalarRepl - Check if instruction I is a safe use with regard to
1606 /// performing scalar replacement of alloca AI. The results are flagged in
1607 /// the Info parameter. Offset indicates the position within AI that is
1608 /// referenced by this instruction.
1609 void SROA::isSafeForScalarRepl(Instruction *I, uint64_t Offset,
1610  AllocaInfo &Info) {
1611  const DataLayout &DL = I->getModule()->getDataLayout();
1612  for (Use &U : I->uses()) {
1613  Instruction *User = cast<Instruction>(U.getUser());
1614 
1615  if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) {
1616  isSafeForScalarRepl(BC, Offset, Info);
1617  } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
1618  uint64_t GEPOffset = Offset;
1619  isSafeGEP(GEPI, GEPOffset, Info);
1620  if (!Info.isUnsafe)
1621  isSafeForScalarRepl(GEPI, GEPOffset, Info);
1622  } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
1623  ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
1624  if (!Length || Length->isNegative())
1625  return MarkUnsafe(Info, User);
1626 
1627  isSafeMemAccess(Offset, Length->getZExtValue(), nullptr,
1628  U.getOperandNo() == 0, Info, MI,
1629  true /*AllowWholeAccess*/);
1630  } else if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
1631  if (!LI->isSimple())
1632  return MarkUnsafe(Info, User);
1633  Type *LIType = LI->getType();
1634  isSafeMemAccess(Offset, DL.getTypeAllocSize(LIType), LIType, false, Info,
1635  LI, true /*AllowWholeAccess*/);
1636  Info.hasALoadOrStore = true;
1637 
1638  } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
1639  // Store is ok if storing INTO the pointer, not storing the pointer
1640  if (!SI->isSimple() || SI->getOperand(0) == I)
1641  return MarkUnsafe(Info, User);
1642 
1643  Type *SIType = SI->getOperand(0)->getType();
1644  isSafeMemAccess(Offset, DL.getTypeAllocSize(SIType), SIType, true, Info,
1645  SI, true /*AllowWholeAccess*/);
1646  Info.hasALoadOrStore = true;
1647  } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(User)) {
1648  if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
1649  II->getIntrinsicID() != Intrinsic::lifetime_end)
1650  return MarkUnsafe(Info, User);
1651  } else if (isa<PHINode>(User) || isa<SelectInst>(User)) {
1652  isSafePHISelectUseForScalarRepl(User, Offset, Info);
1653  } else {
1654  return MarkUnsafe(Info, User);
1655  }
1656  if (Info.isUnsafe) return;
1657  }
1658 }
1659 
1660 
1661 /// isSafePHIUseForScalarRepl - If we see a PHI node or select using a pointer
1662 /// derived from the alloca, we can often still split the alloca into elements.
1663 /// This is useful if we have a large alloca where one element is phi'd
1664 /// together somewhere: we can SRoA and promote all the other elements even if
1665 /// we end up not being able to promote this one.
1666 ///
1667 /// All we require is that the uses of the PHI do not index into other parts of
1668 /// the alloca. The most important use case for this is single load and stores
1669 /// that are PHI'd together, which can happen due to code sinking.
1670 void SROA::isSafePHISelectUseForScalarRepl(Instruction *I, uint64_t Offset,
1671  AllocaInfo &Info) {
1672  // If we've already checked this PHI, don't do it again.
1673  if (PHINode *PN = dyn_cast<PHINode>(I))
1674  if (!Info.CheckedPHIs.insert(PN).second)
1675  return;
1676 
1677  const DataLayout &DL = I->getModule()->getDataLayout();
1678  for (User *U : I->users()) {
1679  Instruction *UI = cast<Instruction>(U);
1680 
1681  if (BitCastInst *BC = dyn_cast<BitCastInst>(UI)) {
1682  isSafePHISelectUseForScalarRepl(BC, Offset, Info);
1683  } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(UI)) {
1684  // Only allow "bitcast" GEPs for simplicity. We could generalize this,
1685  // but would have to prove that we're staying inside of an element being
1686  // promoted.
1687  if (!GEPI->hasAllZeroIndices())
1688  return MarkUnsafe(Info, UI);
1689  isSafePHISelectUseForScalarRepl(GEPI, Offset, Info);
1690  } else if (LoadInst *LI = dyn_cast<LoadInst>(UI)) {
1691  if (!LI->isSimple())
1692  return MarkUnsafe(Info, UI);
1693  Type *LIType = LI->getType();
1694  isSafeMemAccess(Offset, DL.getTypeAllocSize(LIType), LIType, false, Info,
1695  LI, false /*AllowWholeAccess*/);
1696  Info.hasALoadOrStore = true;
1697 
1698  } else if (StoreInst *SI = dyn_cast<StoreInst>(UI)) {
1699  // Store is ok if storing INTO the pointer, not storing the pointer
1700  if (!SI->isSimple() || SI->getOperand(0) == I)
1701  return MarkUnsafe(Info, UI);
1702 
1703  Type *SIType = SI->getOperand(0)->getType();
1704  isSafeMemAccess(Offset, DL.getTypeAllocSize(SIType), SIType, true, Info,
1705  SI, false /*AllowWholeAccess*/);
1706  Info.hasALoadOrStore = true;
1707  } else if (isa<PHINode>(UI) || isa<SelectInst>(UI)) {
1708  isSafePHISelectUseForScalarRepl(UI, Offset, Info);
1709  } else {
1710  return MarkUnsafe(Info, UI);
1711  }
1712  if (Info.isUnsafe) return;
1713  }
1714 }
1715 
1716 /// isSafeGEP - Check if a GEP instruction can be handled for scalar
1717 /// replacement. It is safe when all the indices are constant, in-bounds
1718 /// references, and when the resulting offset corresponds to an element within
1719 /// the alloca type. The results are flagged in the Info parameter. Upon
1720 /// return, Offset is adjusted as specified by the GEP indices.
1721 void SROA::isSafeGEP(GetElementPtrInst *GEPI,
1722  uint64_t &Offset, AllocaInfo &Info) {
1723  gep_type_iterator GEPIt = gep_type_begin(GEPI), E = gep_type_end(GEPI);
1724  if (GEPIt == E)
1725  return;
1726  bool NonConstant = false;
1727  unsigned NonConstantIdxSize = 0;
1728 
1729  // Walk through the GEP type indices, checking the types that this indexes
1730  // into.
1731  for (; GEPIt != E; ++GEPIt) {
1732  // Ignore struct elements, no extra checking needed for these.
1733  if ((*GEPIt)->isStructTy())
1734  continue;
1735 
1736  ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
1737  if (!IdxVal)
1738  return MarkUnsafe(Info, GEPI);
1739  }
1740 
1741  // Compute the offset due to this GEP and check if the alloca has a
1742  // component element at that offset.
1743  SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
1744  // If this GEP is non-constant then the last operand must have been a
1745  // dynamic index into a vector. Pop this now as it has no impact on the
1746  // constant part of the offset.
1747  if (NonConstant)
1748  Indices.pop_back();
1749 
1750  const DataLayout &DL = GEPI->getModule()->getDataLayout();
1751  Offset += DL.getIndexedOffset(GEPI->getPointerOperandType(), Indices);
1752  if (!TypeHasComponent(Info.AI->getAllocatedType(), Offset, NonConstantIdxSize,
1753  DL))
1754  MarkUnsafe(Info, GEPI);
1755 }
1756 
1757 /// isHomogeneousAggregate - Check if type T is a struct or array containing
1758 /// elements of the same type (which is always true for arrays). If so,
1759 /// return true with NumElts and EltTy set to the number of elements and the
1760 /// element type, respectively.
1761 static bool isHomogeneousAggregate(Type *T, unsigned &NumElts,
1762  Type *&EltTy) {
1763  if (ArrayType *AT = dyn_cast<ArrayType>(T)) {
1764  NumElts = AT->getNumElements();
1765  EltTy = (NumElts == 0 ? nullptr : AT->getElementType());
1766  return true;
1767  }
1768  if (StructType *ST = dyn_cast<StructType>(T)) {
1769  NumElts = ST->getNumContainedTypes();
1770  EltTy = (NumElts == 0 ? nullptr : ST->getContainedType(0));
1771  for (unsigned n = 1; n < NumElts; ++n) {
1772  if (ST->getContainedType(n) != EltTy)
1773  return false;
1774  }
1775  return true;
1776  }
1777  return false;
1778 }
1779 
1780 /// isCompatibleAggregate - Check if T1 and T2 are either the same type or are
1781 /// "homogeneous" aggregates with the same element type and number of elements.
1782 static bool isCompatibleAggregate(Type *T1, Type *T2) {
1783  if (T1 == T2)
1784  return true;
1785 
1786  unsigned NumElts1, NumElts2;
1787  Type *EltTy1, *EltTy2;
1788  if (isHomogeneousAggregate(T1, NumElts1, EltTy1) &&
1789  isHomogeneousAggregate(T2, NumElts2, EltTy2) &&
1790  NumElts1 == NumElts2 &&
1791  EltTy1 == EltTy2)
1792  return true;
1793 
1794  return false;
1795 }
1796 
1797 /// isSafeMemAccess - Check if a load/store/memcpy operates on the entire AI
1798 /// alloca or has an offset and size that corresponds to a component element
1799 /// within it. The offset checked here may have been formed from a GEP with a
1800 /// pointer bitcasted to a different type.
1801 ///
1802 /// If AllowWholeAccess is true, then this allows uses of the entire alloca as a
1803 /// unit. If false, it only allows accesses known to be in a single element.
1804 void SROA::isSafeMemAccess(uint64_t Offset, uint64_t MemSize,
1805  Type *MemOpType, bool isStore,
1806  AllocaInfo &Info, Instruction *TheAccess,
1807  bool AllowWholeAccess) {
1808  const DataLayout &DL = TheAccess->getModule()->getDataLayout();
1809  // Check if this is a load/store of the entire alloca.
1810  if (Offset == 0 && AllowWholeAccess &&
1811  MemSize == DL.getTypeAllocSize(Info.AI->getAllocatedType())) {
1812  // This can be safe for MemIntrinsics (where MemOpType is 0) and integer
1813  // loads/stores (which are essentially the same as the MemIntrinsics with
1814  // regard to copying padding between elements). But, if an alloca is
1815  // flagged as both a source and destination of such operations, we'll need
1816  // to check later for padding between elements.
1817  if (!MemOpType || MemOpType->isIntegerTy()) {
1818  if (isStore)
1819  Info.isMemCpyDst = true;
1820  else
1821  Info.isMemCpySrc = true;
1822  return;
1823  }
1824  // This is also safe for references using a type that is compatible with
1825  // the type of the alloca, so that loads/stores can be rewritten using
1826  // insertvalue/extractvalue.
1827  if (isCompatibleAggregate(MemOpType, Info.AI->getAllocatedType())) {
1828  Info.hasSubelementAccess = true;
1829  return;
1830  }
1831  }
1832  // Check if the offset/size correspond to a component within the alloca type.
1833  Type *T = Info.AI->getAllocatedType();
1834  if (TypeHasComponent(T, Offset, MemSize, DL)) {
1835  Info.hasSubelementAccess = true;
1836  return;
1837  }
1838 
1839  return MarkUnsafe(Info, TheAccess);
1840 }
1841 
1842 /// TypeHasComponent - Return true if T has a component type with the
1843 /// specified offset and size. If Size is zero, do not check the size.
1844 bool SROA::TypeHasComponent(Type *T, uint64_t Offset, uint64_t Size,
1845  const DataLayout &DL) {
1846  Type *EltTy;
1847  uint64_t EltSize;
1848  if (StructType *ST = dyn_cast<StructType>(T)) {
1849  const StructLayout *Layout = DL.getStructLayout(ST);
1850  unsigned EltIdx = Layout->getElementContainingOffset(Offset);
1851  EltTy = ST->getContainedType(EltIdx);
1852  EltSize = DL.getTypeAllocSize(EltTy);
1853  Offset -= Layout->getElementOffset(EltIdx);
1854  } else if (ArrayType *AT = dyn_cast<ArrayType>(T)) {
1855  EltTy = AT->getElementType();
1856  EltSize = DL.getTypeAllocSize(EltTy);
1857  if (Offset >= AT->getNumElements() * EltSize)
1858  return false;
1859  Offset %= EltSize;
1860  } else if (VectorType *VT = dyn_cast<VectorType>(T)) {
1861  EltTy = VT->getElementType();
1862  EltSize = DL.getTypeAllocSize(EltTy);
1863  if (Offset >= VT->getNumElements() * EltSize)
1864  return false;
1865  Offset %= EltSize;
1866  } else {
1867  return false;
1868  }
1869  if (Offset == 0 && (Size == 0 || EltSize == Size))
1870  return true;
1871  // Check if the component spans multiple elements.
1872  if (Offset + Size > EltSize)
1873  return false;
1874  return TypeHasComponent(EltTy, Offset, Size, DL);
1875 }
1876 
1877 /// RewriteForScalarRepl - Alloca AI is being split into NewElts, so rewrite
1878 /// the instruction I, which references it, to use the separate elements.
1879 /// Offset indicates the position within AI that is referenced by this
1880 /// instruction.
1881 void SROA::RewriteForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset,
1882  SmallVectorImpl<AllocaInst *> &NewElts) {
1883  const DataLayout &DL = I->getModule()->getDataLayout();
1884  for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI!=E;) {
1885  Use &TheUse = *UI++;
1886  Instruction *User = cast<Instruction>(TheUse.getUser());
1887 
1888  if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) {
1889  RewriteBitCast(BC, AI, Offset, NewElts);
1890  continue;
1891  }
1892 
1893  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) {
1894  RewriteGEP(GEPI, AI, Offset, NewElts);
1895  continue;
1896  }
1897 
1898  if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) {
1899  ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength());
1900  uint64_t MemSize = Length->getZExtValue();
1901  if (Offset == 0 && MemSize == DL.getTypeAllocSize(AI->getAllocatedType()))
1902  RewriteMemIntrinUserOfAlloca(MI, I, AI, NewElts);
1903  // Otherwise the intrinsic can only touch a single element and the
1904  // address operand will be updated, so nothing else needs to be done.
1905  continue;
1906  }
1907 
1908  if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(User)) {
1909  if (II->getIntrinsicID() == Intrinsic::lifetime_start ||
1910  II->getIntrinsicID() == Intrinsic::lifetime_end) {
1911  RewriteLifetimeIntrinsic(II, AI, Offset, NewElts);
1912  }
1913  continue;
1914  }
1915 
1916  if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
1917  Type *LIType = LI->getType();
1918 
1919  if (isCompatibleAggregate(LIType, AI->getAllocatedType())) {
1920  // Replace:
1921  // %res = load { i32, i32 }* %alloc
1922  // with:
1923  // %load.0 = load i32* %alloc.0
1924  // %insert.0 insertvalue { i32, i32 } zeroinitializer, i32 %load.0, 0
1925  // %load.1 = load i32* %alloc.1
1926  // %insert = insertvalue { i32, i32 } %insert.0, i32 %load.1, 1
1927  // (Also works for arrays instead of structs)
1928  Value *Insert = UndefValue::get(LIType);
1929  IRBuilder<> Builder(LI);
1930  for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
1931  Value *Load = Builder.CreateLoad(NewElts[i], "load");
1932  Insert = Builder.CreateInsertValue(Insert, Load, i, "insert");
1933  }
1934  LI->replaceAllUsesWith(Insert);
1935  DeadInsts.push_back(LI);
1936  } else if (LIType->isIntegerTy() &&
1937  DL.getTypeAllocSize(LIType) ==
1938  DL.getTypeAllocSize(AI->getAllocatedType())) {
1939  // If this is a load of the entire alloca to an integer, rewrite it.
1940  RewriteLoadUserOfWholeAlloca(LI, AI, NewElts);
1941  }
1942  continue;
1943  }
1944 
1945  if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
1946  Value *Val = SI->getOperand(0);
1947  Type *SIType = Val->getType();
1948  if (isCompatibleAggregate(SIType, AI->getAllocatedType())) {
1949  // Replace:
1950  // store { i32, i32 } %val, { i32, i32 }* %alloc
1951  // with:
1952  // %val.0 = extractvalue { i32, i32 } %val, 0
1953  // store i32 %val.0, i32* %alloc.0
1954  // %val.1 = extractvalue { i32, i32 } %val, 1
1955  // store i32 %val.1, i32* %alloc.1
1956  // (Also works for arrays instead of structs)
1957  IRBuilder<> Builder(SI);
1958  for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
1959  Value *Extract = Builder.CreateExtractValue(Val, i, Val->getName());
1960  Builder.CreateStore(Extract, NewElts[i]);
1961  }
1962  DeadInsts.push_back(SI);
1963  } else if (SIType->isIntegerTy() &&
1964  DL.getTypeAllocSize(SIType) ==
1965  DL.getTypeAllocSize(AI->getAllocatedType())) {
1966  // If this is a store of the entire alloca from an integer, rewrite it.
1967  RewriteStoreUserOfWholeAlloca(SI, AI, NewElts);
1968  }
1969  continue;
1970  }
1971 
1972  if (isa<SelectInst>(User) || isa<PHINode>(User)) {
1973  // If we have a PHI user of the alloca itself (as opposed to a GEP or
1974  // bitcast) we have to rewrite it. GEP and bitcast uses will be RAUW'd to
1975  // the new pointer.
1976  if (!isa<AllocaInst>(I)) continue;
1977 
1978  assert(Offset == 0 && NewElts[0] &&
1979  "Direct alloca use should have a zero offset");
1980 
1981  // If we have a use of the alloca, we know the derived uses will be
1982  // utilizing just the first element of the scalarized result. Insert a
1983  // bitcast of the first alloca before the user as required.
1984  AllocaInst *NewAI = NewElts[0];
1985  BitCastInst *BCI = new BitCastInst(NewAI, AI->getType(), "", NewAI);
1986  NewAI->moveBefore(BCI);
1987  TheUse = BCI;
1988  continue;
1989  }
1990  }
1991 }
1992 
1993 /// RewriteBitCast - Update a bitcast reference to the alloca being replaced
1994 /// and recursively continue updating all of its uses.
1995 void SROA::RewriteBitCast(BitCastInst *BC, AllocaInst *AI, uint64_t Offset,
1996  SmallVectorImpl<AllocaInst *> &NewElts) {
1997  RewriteForScalarRepl(BC, AI, Offset, NewElts);
1998  if (BC->getOperand(0) != AI)
1999  return;
2000 
2001  // The bitcast references the original alloca. Replace its uses with
2002  // references to the alloca containing offset zero (which is normally at
2003  // index zero, but might not be in cases involving structs with elements
2004  // of size zero).
2005  Type *T = AI->getAllocatedType();
2006  uint64_t EltOffset = 0;
2007  Type *IdxTy;
2008  uint64_t Idx = FindElementAndOffset(T, EltOffset, IdxTy,
2009  BC->getModule()->getDataLayout());
2010  Instruction *Val = NewElts[Idx];
2011  if (Val->getType() != BC->getDestTy()) {
2012  Val = new BitCastInst(Val, BC->getDestTy(), "", BC);
2013  Val->takeName(BC);
2014  }
2015  BC->replaceAllUsesWith(Val);
2016  DeadInsts.push_back(BC);
2017 }
2018 
2019 /// FindElementAndOffset - Return the index of the element containing Offset
2020 /// within the specified type, which must be either a struct or an array.
2021 /// Sets T to the type of the element and Offset to the offset within that
2022 /// element. IdxTy is set to the type of the index result to be used in a
2023 /// GEP instruction.
2024 uint64_t SROA::FindElementAndOffset(Type *&T, uint64_t &Offset, Type *&IdxTy,
2025  const DataLayout &DL) {
2026  uint64_t Idx = 0;
2027 
2028  if (StructType *ST = dyn_cast<StructType>(T)) {
2029  const StructLayout *Layout = DL.getStructLayout(ST);
2030  Idx = Layout->getElementContainingOffset(Offset);
2031  T = ST->getContainedType(Idx);
2032  Offset -= Layout->getElementOffset(Idx);
2033  IdxTy = Type::getInt32Ty(T->getContext());
2034  return Idx;
2035  } else if (ArrayType *AT = dyn_cast<ArrayType>(T)) {
2036  T = AT->getElementType();
2037  uint64_t EltSize = DL.getTypeAllocSize(T);
2038  Idx = Offset / EltSize;
2039  Offset -= Idx * EltSize;
2040  IdxTy = Type::getInt64Ty(T->getContext());
2041  return Idx;
2042  }
2043  VectorType *VT = cast<VectorType>(T);
2044  T = VT->getElementType();
2045  uint64_t EltSize = DL.getTypeAllocSize(T);
2046  Idx = Offset / EltSize;
2047  Offset -= Idx * EltSize;
2048  IdxTy = Type::getInt64Ty(T->getContext());
2049  return Idx;
2050 }
2051 
2052 /// RewriteGEP - Check if this GEP instruction moves the pointer across
2053 /// elements of the alloca that are being split apart, and if so, rewrite
2054 /// the GEP to be relative to the new element.
2055 void SROA::RewriteGEP(GetElementPtrInst *GEPI, AllocaInst *AI, uint64_t Offset,
2056  SmallVectorImpl<AllocaInst *> &NewElts) {
2057  uint64_t OldOffset = Offset;
2058  const DataLayout &DL = GEPI->getModule()->getDataLayout();
2059  SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end());
2060  // If the GEP was dynamic then it must have been a dynamic vector lookup.
2061  // In this case, it must be the last GEP operand which is dynamic so keep that
2062  // aside until we've found the constant GEP offset then add it back in at the
2063  // end.
2064  Value* NonConstantIdx = nullptr;
2065  if (!GEPI->hasAllConstantIndices())
2066  NonConstantIdx = Indices.pop_back_val();
2067  Offset += DL.getIndexedOffset(GEPI->getPointerOperandType(), Indices);
2068 
2069  RewriteForScalarRepl(GEPI, AI, Offset, NewElts);
2070 
2071  Type *T = AI->getAllocatedType();
2072  Type *IdxTy;
2073  uint64_t OldIdx = FindElementAndOffset(T, OldOffset, IdxTy, DL);
2074  if (GEPI->getOperand(0) == AI)
2075  OldIdx = ~0ULL; // Force the GEP to be rewritten.
2076 
2077  T = AI->getAllocatedType();
2078  uint64_t EltOffset = Offset;
2079  uint64_t Idx = FindElementAndOffset(T, EltOffset, IdxTy, DL);
2080 
2081  // If this GEP does not move the pointer across elements of the alloca
2082  // being split, then it does not needs to be rewritten.
2083  if (Idx == OldIdx)
2084  return;
2085 
2086  Type *i32Ty = Type::getInt32Ty(AI->getContext());
2087  SmallVector<Value*, 8> NewArgs;
2088  NewArgs.push_back(Constant::getNullValue(i32Ty));
2089  while (EltOffset != 0) {
2090  uint64_t EltIdx = FindElementAndOffset(T, EltOffset, IdxTy, DL);
2091  NewArgs.push_back(ConstantInt::get(IdxTy, EltIdx));
2092  }
2093  if (NonConstantIdx) {
2094  Type* GepTy = T;
2095  // This GEP has a dynamic index. We need to add "i32 0" to index through
2096  // any structs or arrays in the original type until we get to the vector
2097  // to index.
2098  while (!isa<VectorType>(GepTy)) {
2099  NewArgs.push_back(Constant::getNullValue(i32Ty));
2100  GepTy = cast<CompositeType>(GepTy)->getTypeAtIndex(0U);
2101  }
2102  NewArgs.push_back(NonConstantIdx);
2103  }
2104  Instruction *Val = NewElts[Idx];
2105  if (NewArgs.size() > 1) {
2106  Val = GetElementPtrInst::CreateInBounds(Val, NewArgs, "", GEPI);
2107  Val->takeName(GEPI);
2108  }
2109  if (Val->getType() != GEPI->getType())
2110  Val = new BitCastInst(Val, GEPI->getType(), Val->getName(), GEPI);
2111  GEPI->replaceAllUsesWith(Val);
2112  DeadInsts.push_back(GEPI);
2113 }
2114 
2115 /// RewriteLifetimeIntrinsic - II is a lifetime.start/lifetime.end. Rewrite it
2116 /// to mark the lifetime of the scalarized memory.
2117 void SROA::RewriteLifetimeIntrinsic(IntrinsicInst *II, AllocaInst *AI,
2118  uint64_t Offset,
2119  SmallVectorImpl<AllocaInst *> &NewElts) {
2120  ConstantInt *OldSize = cast<ConstantInt>(II->getArgOperand(0));
2121  // Put matching lifetime markers on everything from Offset up to
2122  // Offset+OldSize.
2123  Type *AIType = AI->getAllocatedType();
2124  const DataLayout &DL = II->getModule()->getDataLayout();
2125  uint64_t NewOffset = Offset;
2126  Type *IdxTy;
2127  uint64_t Idx = FindElementAndOffset(AIType, NewOffset, IdxTy, DL);
2128 
2129  IRBuilder<> Builder(II);
2130  uint64_t Size = OldSize->getLimitedValue();
2131 
2132  if (NewOffset) {
2133  // Splice the first element and index 'NewOffset' bytes in. SROA will
2134  // split the alloca again later.
2135  unsigned AS = AI->getType()->getAddressSpace();
2136  Value *V = Builder.CreateBitCast(NewElts[Idx], Builder.getInt8PtrTy(AS));
2137  V = Builder.CreateGEP(Builder.getInt8Ty(), V, Builder.getInt64(NewOffset));
2138 
2139  IdxTy = NewElts[Idx]->getAllocatedType();
2140  uint64_t EltSize = DL.getTypeAllocSize(IdxTy) - NewOffset;
2141  if (EltSize > Size) {
2142  EltSize = Size;
2143  Size = 0;
2144  } else {
2145  Size -= EltSize;
2146  }
2147  if (II->getIntrinsicID() == Intrinsic::lifetime_start)
2148  Builder.CreateLifetimeStart(V, Builder.getInt64(EltSize));
2149  else
2150  Builder.CreateLifetimeEnd(V, Builder.getInt64(EltSize));
2151  ++Idx;
2152  }
2153 
2154  for (; Idx != NewElts.size() && Size; ++Idx) {
2155  IdxTy = NewElts[Idx]->getAllocatedType();
2156  uint64_t EltSize = DL.getTypeAllocSize(IdxTy);
2157  if (EltSize > Size) {
2158  EltSize = Size;
2159  Size = 0;
2160  } else {
2161  Size -= EltSize;
2162  }
2163  if (II->getIntrinsicID() == Intrinsic::lifetime_start)
2164  Builder.CreateLifetimeStart(NewElts[Idx],
2165  Builder.getInt64(EltSize));
2166  else
2167  Builder.CreateLifetimeEnd(NewElts[Idx],
2168  Builder.getInt64(EltSize));
2169  }
2170  DeadInsts.push_back(II);
2171 }
2172 
2173 /// RewriteMemIntrinUserOfAlloca - MI is a memcpy/memset/memmove from or to AI.
2174 /// Rewrite it to copy or set the elements of the scalarized memory.
2175 void
2176 SROA::RewriteMemIntrinUserOfAlloca(MemIntrinsic *MI, Instruction *Inst,
2177  AllocaInst *AI,
2178  SmallVectorImpl<AllocaInst *> &NewElts) {
2179  // If this is a memcpy/memmove, construct the other pointer as the
2180  // appropriate type. The "Other" pointer is the pointer that goes to memory
2181  // that doesn't have anything to do with the alloca that we are promoting. For
2182  // memset, this Value* stays null.
2183  Value *OtherPtr = nullptr;
2184  unsigned MemAlignment = MI->getAlignment();
2185  if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) { // memmove/memcopy
2186  if (Inst == MTI->getRawDest())
2187  OtherPtr = MTI->getRawSource();
2188  else {
2189  assert(Inst == MTI->getRawSource());
2190  OtherPtr = MTI->getRawDest();
2191  }
2192  }
2193 
2194  // If there is an other pointer, we want to convert it to the same pointer
2195  // type as AI has, so we can GEP through it safely.
2196  if (OtherPtr) {
2197  unsigned AddrSpace =
2198  cast<PointerType>(OtherPtr->getType())->getAddressSpace();
2199 
2200  // Remove bitcasts and all-zero GEPs from OtherPtr. This is an
2201  // optimization, but it's also required to detect the corner case where
2202  // both pointer operands are referencing the same memory, and where
2203  // OtherPtr may be a bitcast or GEP that currently being rewritten. (This
2204  // function is only called for mem intrinsics that access the whole
2205  // aggregate, so non-zero GEPs are not an issue here.)
2206  OtherPtr = OtherPtr->stripPointerCasts();
2207 
2208  // Copying the alloca to itself is a no-op: just delete it.
2209  if (OtherPtr == AI || OtherPtr == NewElts[0]) {
2210  // This code will run twice for a no-op memcpy -- once for each operand.
2211  // Put only one reference to MI on the DeadInsts list.
2212  for (SmallVectorImpl<Value *>::const_iterator I = DeadInsts.begin(),
2213  E = DeadInsts.end(); I != E; ++I)
2214  if (*I == MI) return;
2215  DeadInsts.push_back(MI);
2216  return;
2217  }
2218 
2219  // If the pointer is not the right type, insert a bitcast to the right
2220  // type.
2221  Type *NewTy =
2222  PointerType::get(AI->getType()->getElementType(), AddrSpace);
2223 
2224  if (OtherPtr->getType() != NewTy)
2225  OtherPtr = new BitCastInst(OtherPtr, NewTy, OtherPtr->getName(), MI);
2226  }
2227 
2228  // Process each element of the aggregate.
2229  bool SROADest = MI->getRawDest() == Inst;
2230 
2232  const DataLayout &DL = MI->getModule()->getDataLayout();
2233 
2234  for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
2235  // If this is a memcpy/memmove, emit a GEP of the other element address.
2236  Value *OtherElt = nullptr;
2237  unsigned OtherEltAlign = MemAlignment;
2238 
2239  if (OtherPtr) {
2240  Value *Idx[2] = { Zero,
2242  OtherElt = GetElementPtrInst::CreateInBounds(OtherPtr, Idx,
2243  OtherPtr->getName()+"."+Twine(i),
2244  MI);
2245  uint64_t EltOffset;
2246  PointerType *OtherPtrTy = cast<PointerType>(OtherPtr->getType());
2247  Type *OtherTy = OtherPtrTy->getElementType();
2248  if (StructType *ST = dyn_cast<StructType>(OtherTy)) {
2249  EltOffset = DL.getStructLayout(ST)->getElementOffset(i);
2250  } else {
2251  Type *EltTy = cast<SequentialType>(OtherTy)->getElementType();
2252  EltOffset = DL.getTypeAllocSize(EltTy) * i;
2253  }
2254 
2255  // The alignment of the other pointer is the guaranteed alignment of the
2256  // element, which is affected by both the known alignment of the whole
2257  // mem intrinsic and the alignment of the element. If the alignment of
2258  // the memcpy (f.e.) is 32 but the element is at a 4-byte offset, then the
2259  // known alignment is just 4 bytes.
2260  OtherEltAlign = (unsigned)MinAlign(OtherEltAlign, EltOffset);
2261  }
2262 
2263  Value *EltPtr = NewElts[i];
2264  Type *EltTy = cast<PointerType>(EltPtr->getType())->getElementType();
2265 
2266  // If we got down to a scalar, insert a load or store as appropriate.
2267  if (EltTy->isSingleValueType()) {
2268  if (isa<MemTransferInst>(MI)) {
2269  if (SROADest) {
2270  // From Other to Alloca.
2271  Value *Elt = new LoadInst(OtherElt, "tmp", false, OtherEltAlign, MI);
2272  new StoreInst(Elt, EltPtr, MI);
2273  } else {
2274  // From Alloca to Other.
2275  Value *Elt = new LoadInst(EltPtr, "tmp", MI);
2276  new StoreInst(Elt, OtherElt, false, OtherEltAlign, MI);
2277  }
2278  continue;
2279  }
2280  assert(isa<MemSetInst>(MI));
2281 
2282  // If the stored element is zero (common case), just store a null
2283  // constant.
2284  Constant *StoreVal;
2285  if (ConstantInt *CI = dyn_cast<ConstantInt>(MI->getArgOperand(1))) {
2286  if (CI->isZero()) {
2287  StoreVal = Constant::getNullValue(EltTy); // 0.0, null, 0, <0,0>
2288  } else {
2289  // If EltTy is a vector type, get the element type.
2290  Type *ValTy = EltTy->getScalarType();
2291 
2292  // Construct an integer with the right value.
2293  unsigned EltSize = DL.getTypeSizeInBits(ValTy);
2294  APInt OneVal(EltSize, CI->getZExtValue());
2295  APInt TotalVal(OneVal);
2296  // Set each byte.
2297  for (unsigned i = 0; 8*i < EltSize; ++i) {
2298  TotalVal = TotalVal.shl(8);
2299  TotalVal |= OneVal;
2300  }
2301 
2302  // Convert the integer value to the appropriate type.
2303  StoreVal = ConstantInt::get(CI->getContext(), TotalVal);
2304  if (ValTy->isPointerTy())
2305  StoreVal = ConstantExpr::getIntToPtr(StoreVal, ValTy);
2306  else if (ValTy->isFloatingPointTy())
2307  StoreVal = ConstantExpr::getBitCast(StoreVal, ValTy);
2308  assert(StoreVal->getType() == ValTy && "Type mismatch!");
2309 
2310  // If the requested value was a vector constant, create it.
2311  if (EltTy->isVectorTy()) {
2312  unsigned NumElts = cast<VectorType>(EltTy)->getNumElements();
2313  StoreVal = ConstantVector::getSplat(NumElts, StoreVal);
2314  }
2315  }
2316  new StoreInst(StoreVal, EltPtr, MI);
2317  continue;
2318  }
2319  // Otherwise, if we're storing a byte variable, use a memset call for
2320  // this element.
2321  }
2322 
2323  unsigned EltSize = DL.getTypeAllocSize(EltTy);
2324  if (!EltSize)
2325  continue;
2326 
2327  IRBuilder<> Builder(MI);
2328 
2329  // Finally, insert the meminst for this element.
2330  if (isa<MemSetInst>(MI)) {
2331  Builder.CreateMemSet(EltPtr, MI->getArgOperand(1), EltSize,
2332  MI->isVolatile());
2333  } else {
2334  assert(isa<MemTransferInst>(MI));
2335  Value *Dst = SROADest ? EltPtr : OtherElt; // Dest ptr
2336  Value *Src = SROADest ? OtherElt : EltPtr; // Src ptr
2337 
2338  if (isa<MemCpyInst>(MI))
2339  Builder.CreateMemCpy(Dst, Src, EltSize, OtherEltAlign,MI->isVolatile());
2340  else
2341  Builder.CreateMemMove(Dst, Src, EltSize,OtherEltAlign,MI->isVolatile());
2342  }
2343  }
2344  DeadInsts.push_back(MI);
2345 }
2346 
2347 /// RewriteStoreUserOfWholeAlloca - We found a store of an integer that
2348 /// overwrites the entire allocation. Extract out the pieces of the stored
2349 /// integer and store them individually.
2350 void
2351 SROA::RewriteStoreUserOfWholeAlloca(StoreInst *SI, AllocaInst *AI,
2352  SmallVectorImpl<AllocaInst *> &NewElts) {
2353  // Extract each element out of the integer according to its structure offset
2354  // and store the element value to the individual alloca.
2355  Value *SrcVal = SI->getOperand(0);
2356  Type *AllocaEltTy = AI->getAllocatedType();
2357  const DataLayout &DL = SI->getModule()->getDataLayout();
2358  uint64_t AllocaSizeBits = DL.getTypeAllocSizeInBits(AllocaEltTy);
2359 
2360  IRBuilder<> Builder(SI);
2361 
2362  // Handle tail padding by extending the operand
2363  if (DL.getTypeSizeInBits(SrcVal->getType()) != AllocaSizeBits)
2364  SrcVal = Builder.CreateZExt(SrcVal,
2365  IntegerType::get(SI->getContext(), AllocaSizeBits));
2366 
2367  DEBUG(dbgs() << "PROMOTING STORE TO WHOLE ALLOCA: " << *AI << '\n' << *SI
2368  << '\n');
2369 
2370  // There are two forms here: AI could be an array or struct. Both cases
2371  // have different ways to compute the element offset.
2372  if (StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) {
2373  const StructLayout *Layout = DL.getStructLayout(EltSTy);
2374 
2375  for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
2376  // Get the number of bits to shift SrcVal to get the value.
2377  Type *FieldTy = EltSTy->getElementType(i);
2378  uint64_t Shift = Layout->getElementOffsetInBits(i);
2379 
2380  if (DL.isBigEndian())
2381  Shift = AllocaSizeBits - Shift - DL.getTypeAllocSizeInBits(FieldTy);
2382 
2383  Value *EltVal = SrcVal;
2384  if (Shift) {
2385  Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift);
2386  EltVal = Builder.CreateLShr(EltVal, ShiftVal, "sroa.store.elt");
2387  }
2388 
2389  // Truncate down to an integer of the right size.
2390  uint64_t FieldSizeBits = DL.getTypeSizeInBits(FieldTy);
2391 
2392  // Ignore zero sized fields like {}, they obviously contain no data.
2393  if (FieldSizeBits == 0) continue;
2394 
2395  if (FieldSizeBits != AllocaSizeBits)
2396  EltVal = Builder.CreateTrunc(EltVal,
2397  IntegerType::get(SI->getContext(), FieldSizeBits));
2398  Value *DestField = NewElts[i];
2399  if (EltVal->getType() == FieldTy) {
2400  // Storing to an integer field of this size, just do it.
2401  } else if (FieldTy->isFloatingPointTy() || FieldTy->isVectorTy()) {
2402  // Bitcast to the right element type (for fp/vector values).
2403  EltVal = Builder.CreateBitCast(EltVal, FieldTy);
2404  } else {
2405  // Otherwise, bitcast the dest pointer (for aggregates).
2406  DestField = Builder.CreateBitCast(DestField,
2407  PointerType::getUnqual(EltVal->getType()));
2408  }
2409  new StoreInst(EltVal, DestField, SI);
2410  }
2411 
2412  } else {
2413  ArrayType *ATy = cast<ArrayType>(AllocaEltTy);
2414  Type *ArrayEltTy = ATy->getElementType();
2415  uint64_t ElementOffset = DL.getTypeAllocSizeInBits(ArrayEltTy);
2416  uint64_t ElementSizeBits = DL.getTypeSizeInBits(ArrayEltTy);
2417 
2418  uint64_t Shift;
2419 
2420  if (DL.isBigEndian())
2421  Shift = AllocaSizeBits-ElementOffset;
2422  else
2423  Shift = 0;
2424 
2425  for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
2426  // Ignore zero sized fields like {}, they obviously contain no data.
2427  if (ElementSizeBits == 0) continue;
2428 
2429  Value *EltVal = SrcVal;
2430  if (Shift) {
2431  Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift);
2432  EltVal = Builder.CreateLShr(EltVal, ShiftVal, "sroa.store.elt");
2433  }
2434 
2435  // Truncate down to an integer of the right size.
2436  if (ElementSizeBits != AllocaSizeBits)
2437  EltVal = Builder.CreateTrunc(EltVal,
2439  ElementSizeBits));
2440  Value *DestField = NewElts[i];
2441  if (EltVal->getType() == ArrayEltTy) {
2442  // Storing to an integer field of this size, just do it.
2443  } else if (ArrayEltTy->isFloatingPointTy() ||
2444  ArrayEltTy->isVectorTy()) {
2445  // Bitcast to the right element type (for fp/vector values).
2446  EltVal = Builder.CreateBitCast(EltVal, ArrayEltTy);
2447  } else {
2448  // Otherwise, bitcast the dest pointer (for aggregates).
2449  DestField = Builder.CreateBitCast(DestField,
2450  PointerType::getUnqual(EltVal->getType()));
2451  }
2452  new StoreInst(EltVal, DestField, SI);
2453 
2454  if (DL.isBigEndian())
2455  Shift -= ElementOffset;
2456  else
2457  Shift += ElementOffset;
2458  }
2459  }
2460 
2461  DeadInsts.push_back(SI);
2462 }
2463 
2464 /// RewriteLoadUserOfWholeAlloca - We found a load of the entire allocation to
2465 /// an integer. Load the individual pieces to form the aggregate value.
2466 void
2467 SROA::RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI,
2468  SmallVectorImpl<AllocaInst *> &NewElts) {
2469  // Extract each element out of the NewElts according to its structure offset
2470  // and form the result value.
2471  Type *AllocaEltTy = AI->getAllocatedType();
2472  const DataLayout &DL = LI->getModule()->getDataLayout();
2473  uint64_t AllocaSizeBits = DL.getTypeAllocSizeInBits(AllocaEltTy);
2474 
2475  DEBUG(dbgs() << "PROMOTING LOAD OF WHOLE ALLOCA: " << *AI << '\n' << *LI
2476  << '\n');
2477 
2478  // There are two forms here: AI could be an array or struct. Both cases
2479  // have different ways to compute the element offset.
2480  const StructLayout *Layout = nullptr;
2481  uint64_t ArrayEltBitOffset = 0;
2482  if (StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) {
2483  Layout = DL.getStructLayout(EltSTy);
2484  } else {
2485  Type *ArrayEltTy = cast<ArrayType>(AllocaEltTy)->getElementType();
2486  ArrayEltBitOffset = DL.getTypeAllocSizeInBits(ArrayEltTy);
2487  }
2488 
2489  Value *ResultVal =
2490  Constant::getNullValue(IntegerType::get(LI->getContext(), AllocaSizeBits));
2491 
2492  for (unsigned i = 0, e = NewElts.size(); i != e; ++i) {
2493  // Load the value from the alloca. If the NewElt is an aggregate, cast
2494  // the pointer to an integer of the same size before doing the load.
2495  Value *SrcField = NewElts[i];
2496  Type *FieldTy =
2497  cast<PointerType>(SrcField->getType())->getElementType();
2498  uint64_t FieldSizeBits = DL.getTypeSizeInBits(FieldTy);
2499 
2500  // Ignore zero sized fields like {}, they obviously contain no data.
2501  if (FieldSizeBits == 0) continue;
2502 
2503  IntegerType *FieldIntTy = IntegerType::get(LI->getContext(),
2504  FieldSizeBits);
2505  if (!FieldTy->isIntegerTy() && !FieldTy->isFloatingPointTy() &&
2506  !FieldTy->isVectorTy())
2507  SrcField = new BitCastInst(SrcField,
2508  PointerType::getUnqual(FieldIntTy),
2509  "", LI);
2510  SrcField = new LoadInst(SrcField, "sroa.load.elt", LI);
2511 
2512  // If SrcField is a fp or vector of the right size but that isn't an
2513  // integer type, bitcast to an integer so we can shift it.
2514  if (SrcField->getType() != FieldIntTy)
2515  SrcField = new BitCastInst(SrcField, FieldIntTy, "", LI);
2516 
2517  // Zero extend the field to be the same size as the final alloca so that
2518  // we can shift and insert it.
2519  if (SrcField->getType() != ResultVal->getType())
2520  SrcField = new ZExtInst(SrcField, ResultVal->getType(), "", LI);
2521 
2522  // Determine the number of bits to shift SrcField.
2523  uint64_t Shift;
2524  if (Layout) // Struct case.
2525  Shift = Layout->getElementOffsetInBits(i);
2526  else // Array case.
2527  Shift = i*ArrayEltBitOffset;
2528 
2529  if (DL.isBigEndian())
2530  Shift = AllocaSizeBits-Shift-FieldIntTy->getBitWidth();
2531 
2532  if (Shift) {
2533  Value *ShiftVal = ConstantInt::get(SrcField->getType(), Shift);
2534  SrcField = BinaryOperator::CreateShl(SrcField, ShiftVal, "", LI);
2535  }
2536 
2537  // Don't create an 'or x, 0' on the first iteration.
2538  if (!isa<Constant>(ResultVal) ||
2539  !cast<Constant>(ResultVal)->isNullValue())
2540  ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI);
2541  else
2542  ResultVal = SrcField;
2543  }
2544 
2545  // Handle tail padding by truncating the result
2546  if (DL.getTypeSizeInBits(LI->getType()) != AllocaSizeBits)
2547  ResultVal = new TruncInst(ResultVal, LI->getType(), "", LI);
2548 
2549  LI->replaceAllUsesWith(ResultVal);
2550  DeadInsts.push_back(LI);
2551 }
2552 
2553 /// HasPadding - Return true if the specified type has any structure or
2554 /// alignment padding in between the elements that would be split apart
2555 /// by SROA; return false otherwise.
2556 static bool HasPadding(Type *Ty, const DataLayout &DL) {
2557  if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
2558  Ty = ATy->getElementType();
2559  return DL.getTypeSizeInBits(Ty) != DL.getTypeAllocSizeInBits(Ty);
2560  }
2561 
2562  // SROA currently handles only Arrays and Structs.
2563  StructType *STy = cast<StructType>(Ty);
2564  const StructLayout *SL = DL.getStructLayout(STy);
2565  unsigned PrevFieldBitOffset = 0;
2566  for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
2567  unsigned FieldBitOffset = SL->getElementOffsetInBits(i);
2568 
2569  // Check to see if there is any padding between this element and the
2570  // previous one.
2571  if (i) {
2572  unsigned PrevFieldEnd =
2573  PrevFieldBitOffset+DL.getTypeSizeInBits(STy->getElementType(i-1));
2574  if (PrevFieldEnd < FieldBitOffset)
2575  return true;
2576  }
2577  PrevFieldBitOffset = FieldBitOffset;
2578  }
2579  // Check for tail padding.
2580  if (unsigned EltCount = STy->getNumElements()) {
2581  unsigned PrevFieldEnd = PrevFieldBitOffset +
2582  DL.getTypeSizeInBits(STy->getElementType(EltCount-1));
2583  if (PrevFieldEnd < SL->getSizeInBits())
2584  return true;
2585  }
2586  return false;
2587 }
2588 
2589 /// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of
2590 /// an aggregate can be broken down into elements. Return 0 if not, 3 if safe,
2591 /// or 1 if safe after canonicalization has been performed.
2592 bool SROA::isSafeAllocaToScalarRepl(AllocaInst *AI) {
2593  // Loop over the use list of the alloca. We can only transform it if all of
2594  // the users are safe to transform.
2595  AllocaInfo Info(AI);
2596 
2597  isSafeForScalarRepl(AI, 0, Info);
2598  if (Info.isUnsafe) {
2599  DEBUG(dbgs() << "Cannot transform: " << *AI << '\n');
2600  return false;
2601  }
2602 
2603  const DataLayout &DL = AI->getModule()->getDataLayout();
2604 
2605  // Okay, we know all the users are promotable. If the aggregate is a memcpy
2606  // source and destination, we have to be careful. In particular, the memcpy
2607  // could be moving around elements that live in structure padding of the LLVM
2608  // types, but may actually be used. In these cases, we refuse to promote the
2609  // struct.
2610  if (Info.isMemCpySrc && Info.isMemCpyDst &&
2611  HasPadding(AI->getAllocatedType(), DL))
2612  return false;
2613 
2614  // If the alloca never has an access to just *part* of it, but is accessed
2615  // via loads and stores, then we should use ConvertToScalarInfo to promote
2616  // the alloca instead of promoting each piece at a time and inserting fission
2617  // and fusion code.
2618  if (!Info.hasSubelementAccess && Info.hasALoadOrStore) {
2619  // If the struct/array just has one element, use basic SRoA.
2620  if (StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) {
2621  if (ST->getNumElements() > 1) return false;
2622  } else {
2623  if (cast<ArrayType>(AI->getAllocatedType())->getNumElements() > 1)
2624  return false;
2625  }
2626  }
2627 
2628  return true;
2629 }
Value * CreateLShr(Value *LHS, Value *RHS, const Twine &Name="", bool isExact=false)
Definition: IRBuilder.h:842
unsigned getAlignment() const
static unsigned getBitWidth(Type *Ty, const DataLayout &DL)
Returns the bitwidth of the given scalar or pointer type (if unknown returns 0).
Value * CreateGEP(Value *Ptr, ArrayRef< Value * > IdxList, const Twine &Name="")
Definition: IRBuilder.h:1032
iplist< Instruction >::iterator eraseFromParent()
eraseFromParent - This method unlinks 'this' from the containing basic block and deletes it...
Definition: Instruction.cpp:70
use_iterator use_end()
Definition: Value.h:281
use_iterator_impl< Use > use_iterator
Definition: Value.h:277
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:104
iterator_range< use_iterator > uses()
Definition: Value.h:283
Helper class for SSA formation on a set of values defined in multiple blocks.
Definition: SSAUpdater.h:38
LoadInst * CreateLoad(Value *Ptr, const char *Name)
Definition: IRBuilder.h:973
void addIncoming(Value *V, BasicBlock *BB)
addIncoming - 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...
LLVM Argument representation.
Definition: Argument.h:35
void run(const SmallVectorImpl< Instruction * > &Insts) const
This does the promotion.
Definition: SSAUpdater.cpp:342
STATISTIC(NumFunctions,"Total number of functions")
bool isVolatile() const
FunctionPass * createScalarReplAggregatesPass(signed Threshold=-1, bool UseDomTree=true, signed StructMemberThreshold=-1, signed ArrayElementThreshold=-1, signed ScalarLoadThreshold=-1)
Intrinsic::ID getIntrinsicID() const
getIntrinsicID - Return the intrinsic ID of this intrinsic.
Definition: IntrinsicInst.h:44
static bool isSafeSelectToSpeculate(SelectInst *SI)
isSafeSelectToSpeculate - Select instructions that use an alloca and are subsequently loaded can be r...
This class represents zero extension of integer types.
static APInt getLowBitsSet(unsigned numBits, unsigned loBitsSet)
Get a value with low bits set.
Definition: APInt.h:531
An immutable pass that tracks lazily created AssumptionCache objects.
static PointerType * get(Type *ElementType, unsigned AddressSpace)
PointerType::get - This constructs a pointer to an object of the specified type in a numbered address...
Definition: Type.cpp:738
gep_type_iterator gep_type_end(const User *GEP)
bool mayHaveSideEffects() const
mayHaveSideEffects - Return true if the instruction may have side effects.
Definition: Instruction.h:387
static Constant * getIntToPtr(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1822
A cache of .assume calls within a function.
bool isDoubleTy() const
isDoubleTy - Return true if this is 'double', a 64-bit IEEE fp type.
Definition: Type.h:146
MemSetInst - This class wraps the llvm.memset intrinsic.
F(f)
This class represents a sign extension of integer types.
CallInst * CreateMemSet(Value *Ptr, Value *Val, uint64_t Size, unsigned Align, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memset to the specified pointer and the specified value.
Definition: IRBuilder.h:365
unsigned getAddressSpace() const
Return the address space of the Pointer type.
Definition: DerivedTypes.h:472
LoadInst - an instruction for reading from memory.
Definition: Instructions.h:177
unsigned getBitWidth() const
Get the number of bits in this IntegerType.
Definition: DerivedTypes.h:61
static IntegerType * getInt64Ty(LLVMContext &C)
Definition: Type.cpp:240
Hexagon Common GEP
void reserve(size_type N)
Definition: SmallVector.h:401
bool isSimple() const
Definition: Instructions.h:279
size_type size() const
Determine the number of elements in the SetVector.
Definition: SetVector.h:64
op_iterator op_begin()
Definition: User.h:183
void initializeSROA_DTPass(PassRegistry &)
Tagged DWARF-like metadata node.
uint64_t getTypeAllocSizeInBits(Type *Ty) const
Returns the offset in bits between successive objects of the specified type, including alignment padd...
Definition: DataLayout.h:398
Value * CreateInsertElement(Value *Vec, Value *NewElt, Value *Idx, const Twine &Name="")
Definition: IRBuilder.h:1508
static Constant * getNullValue(Type *Ty)
Definition: Constants.cpp:178
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:188
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:231
bool isSingleValueType() const
isSingleValueType - Return true if the type is a valid type for a register in codegen.
Definition: Type.h:250
bool isArrayAllocation() const
isArrayAllocation - Return true if there is an allocation size parameter to the allocation instructio...
Scalar Replacement of Aggregates(DT)"
Value * CreateExtractValue(Value *Agg, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:1541
AnalysisUsage & addRequired()
Used to lazily calculate structure layout information for a target machine, based on the DataLayout s...
Definition: DataLayout.h:475
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:70
static Value * getPointerOperand(Instruction &Inst)
SelectInst - This class represents the LLVM 'select' instruction.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:79
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:551
T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val()
Definition: SmallVector.h:406
StructType - Class to represent struct types.
Definition: DerivedTypes.h:191
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
Value * CreateIntToPtr(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1249
A Use represents the edge between a Value definition and its users.
Definition: Use.h:69
bool isDereferenceablePointer(const Value *V, const DataLayout &DL, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr, const TargetLibraryInfo *TLI=nullptr)
isDereferenceablePointer - Return true if this is always a dereferenceable pointer.
#define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:75
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APInt.h:33
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:517
unsigned getBitWidth() const
Return the number of bits in the Vector type.
Definition: DerivedTypes.h:436
bool isSized(SmallPtrSetImpl< const Type * > *Visited=nullptr) const
isSized - Return true if it makes sense to take the size of this type.
Definition: Type.h:268
uint64_t getIndexedOffset(Type *Ty, ArrayRef< Value * > Indices) const
Returns the offset from the beginning of the type for the specified indices.
Definition: DataLayout.cpp:721
Type * getPointerOperandType() const
getPointerOperandType - Method to return the pointer operand as a PointerType.
Definition: Instructions.h:971
bool isNegative() const
Definition: Constants.h:156
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:117
void PromoteMemToReg(ArrayRef< AllocaInst * > Allocas, DominatorTree &DT, AliasSetTracker *AST=nullptr, AssumptionCache *AC=nullptr)
Promote the specified list of alloca instructions into scalar registers, inserting PHI nodes as appro...
user_iterator_impl< User > user_iterator
Definition: Value.h:292
static GetElementPtrInst * CreateInBounds(Value *Ptr, ArrayRef< Value * > IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Create an "inbounds" getelementptr.
Definition: Instructions.h:887
Value * CreateAnd(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:878
bool insert(const value_type &X)
Insert a new element into the SetVector.
Definition: SetVector.h:102
LLVMContext & getContext() const
getContext - Return the LLVMContext in which this type was uniqued.
Definition: Type.h:125
Value * CreateOr(Value *LHS, Value *RHS, const Twine &Name="")
Definition: IRBuilder.h:894
#define T
ArrayType - Class to represent array types.
Definition: DerivedTypes.h:336
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:219
CallInst * CreateMemMove(Value *Dst, Value *Src, uint64_t Size, unsigned Align, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memmove between the specified pointers.
Definition: IRBuilder.h:404
This class represents a no-op cast from one type to another.
bool empty() const
Determine if the SetVector is empty or not.
Definition: SetVector.h:59
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: ArrayRef.h:31
bool isFloatingPointTy() const
isFloatingPointTy - Return true if this is one of the six floating point types
Definition: Type.h:159
StoreInst - an instruction for storing to memory.
Definition: Instructions.h:316
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:351
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:256
StoreInst * CreateStore(Value *Val, Value *Ptr, bool isVolatile=false)
Definition: IRBuilder.h:985
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:67
This class represents a truncation of integer types.
Type * getElementType() const
Definition: DerivedTypes.h:323
PointerType - Class to represent pointers.
Definition: DerivedTypes.h:449
unsigned getNumIncomingValues() const
getNumIncomingValues - Return the number of incoming edges
uint64_t getElementOffset(unsigned Idx) const
Definition: DataLayout.h:491
uint64_t getElementOffsetInBits(unsigned Idx) const
Definition: DataLayout.h:496
static Constant * getBitCast(Constant *C, Type *Ty, bool OnlyIfReduced=false)
Definition: Constants.cpp:1835
unsigned getNumSuccessors() const
Return the number of successors that this terminator has.
Definition: InstrTypes.h:57
GetElementPtrInst - an instruction for type-safe pointer arithmetic to access elements of arrays and ...
Definition: Instructions.h:830
#define true
Definition: ConvertUTF.c:66
static MetadataAsValue * getIfExists(LLVMContext &Context, Metadata *MD)
Definition: Metadata.cpp:83
void setAAMetadata(const AAMDNodes &N)
setAAMetadata - Sets the metadata on this instruction from the AAMDNodes structure.
Definition: Metadata.cpp:1122
LLVM Basic Block Representation.
Definition: BasicBlock.h:65
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
This is an important class for using LLVM in a threaded context.
Definition: LLVMContext.h:41
bool isVectorTy() const
isVectorTy - True if this is an instance of VectorType.
Definition: Type.h:226
Value * CreateAdd(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:704
Type * getElementType(unsigned N) const
Definition: DerivedTypes.h:291
Value * CreatePtrToInt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1245
This is an important base class in LLVM.
Definition: Constant.h:41
PointerType * getType() const
getType - Overload to return most specific pointer type
Definition: Instructions.h:115
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool onlyUsedByLifetimeMarkers(const Value *V)
onlyUsedByLifetimeMarkers - Return true if the only users of this pointer are lifetime markers...
bool isFloatTy() const
isFloatTy - Return true if this is 'float', a 32-bit IEEE fp type.
Definition: Type.h:143
unsigned getAlignment() const
getAlignment - Return the alignment of the memory that is being allocated by the instruction.
Definition: Instructions.h:130
Value * getRawDest() const
const DebugLoc & getDebugLoc() const
getDebugLoc - Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:230
Represent the analysis usage information of a pass.
op_iterator op_end()
Definition: User.h:185
BasicBlock * getIncomingBlock(unsigned i) const
getIncomingBlock - Return incoming basic block number i.
static bool isSafePHIToSpeculate(PHINode *PN)
isSafePHIToSpeculate - PHI instructions that use an alloca and are subsequently loaded can be rewritt...
uint64_t getNumElements() const
Definition: DerivedTypes.h:352
User * getUser() const
Returns the User that contains this Use.
Definition: Use.cpp:41
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:294
Value * getOperand(unsigned i) const
Definition: User.h:118
Class to represent integer types.
Definition: DerivedTypes.h:37
ConstantInt * getInt64(uint64_t C)
Get a constant 64-bit value.
Definition: IRBuilder.h:271
void setAlignment(unsigned Align)
bool isPointerTy() const
isPointerTy - True if this is an instance of PointerType.
Definition: Type.h:217
static UndefValue * get(Type *T)
get() - Static factory methods - Return an 'undef' object of the specified type.
Definition: Constants.cpp:1473
bool hasAllConstantIndices() const
hasAllConstantIndices - Return true if all of the indices of this GEP are constant integers...
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:519
PointerType * getInt8PtrTy(unsigned AddrSpace=0)
Fetch the type representing a pointer to an 8-bit integer value.
Definition: IRBuilder.h:346
const Value * getTrueValue() const
Value * GetUnderlyingObject(Value *V, const DataLayout &DL, unsigned MaxLookup=6)
GetUnderlyingObject - This method strips off any GEP address adjustments and pointer casts from the s...
CallInst * CreateLifetimeEnd(Value *Ptr, ConstantInt *Size=nullptr)
Create a lifetime.end intrinsic.
Definition: IRBuilder.cpp:179
static Constant * getSplat(unsigned NumElts, Constant *Elt)
getSplat - Return a ConstantVector with the specified constant in each element.
Definition: Constants.cpp:1162
static IntegerType * get(LLVMContext &C, unsigned NumBits)
This static method is the primary way of constructing an IntegerType.
Definition: Type.cpp:304
DIExpression * getExpression() const
MemIntrinsic - This is the common base class for memset/memcpy/memmove.
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:299
static PointerType * getUnqual(Type *ElementType)
PointerType::getUnqual - This constructs a pointer to an object of the specified type in the generic ...
Definition: DerivedTypes.h:460
This is the shared class of boolean and integer constants.
Definition: Constants.h:47
Value * CreateExtractElement(Value *Vec, Value *Idx, const Twine &Name="")
Definition: IRBuilder.h:1495
Value * CreateZExt(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1192
Value * getIncomingValue(unsigned i) const
getIncomingValue - Return incoming value number x
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:388
iterator end()
Definition: BasicBlock.h:233
Helper class for promoting a collection of loads and stores into SSA Form using the SSAUpdater...
Definition: SSAUpdater.h:134
bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI, StoreInst *SI, DIBuilder &Builder)
===---------------------------------------------------------------——===// Dbg Intrinsic utilities ...
Definition: Local.cpp:979
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:57
Value * CreateBitCast(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1253
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
Module.h This file contains the declarations for the Module class.
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:222
Instruction * user_back()
user_back - Specialize the methods defined in Value, as we know that an instruction can only be used ...
Definition: Instruction.h:69
static LocalAsMetadata * getIfExists(Value *Local)
Definition: Metadata.h:346
void initializeSROA_SSAUpPass(PassRegistry &)
static bool HasPadding(Type *Ty, const DataLayout &DL)
HasPadding - Return true if the specified type has any structure or alignment padding in between the ...
A collection of metadata nodes that might be associated with a memory access used by the alias-analys...
Definition: Metadata.h:548
Type * getDestTy() const
Return the destination type, as a convenience.
Definition: InstrTypes.h:656
ConstantInt * getInt32(uint32_t C)
Get a constant 32-bit value.
Definition: IRBuilder.h:266
SequentialType * getType() const
Definition: Instructions.h:922
Value * stripPointerCasts()
Strip off pointer casts, all-zero GEPs, and aliases.
Definition: Value.cpp:458
unsigned getElementContainingOffset(uint64_t Offset) const
Given a valid byte offset into the structure, returns the structure index that contains it...
Definition: DataLayout.cpp:74
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:582
static PHINode * Create(Type *Ty, unsigned NumReservedValues, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Constructors - NumReservedValues is a hint for the number of incoming edges that this phi node will h...
void setPreservesCFG()
This function should be called by the pass, iff they do not:
Definition: Pass.cpp:263
const BasicBlock & getEntryBlock() const
Definition: Function.h:442
static cl::opt< AlignMode > Align(cl::desc("Load/store alignment support"), cl::Hidden, cl::init(NoStrictAlign), cl::values(clEnumValN(StrictAlign,"aarch64-strict-align","Disallow all unaligned memory accesses"), clEnumValN(NoStrictAlign,"aarch64-no-strict-align","Allow unaligned memory accesses"), clEnumValEnd))
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
Value * getArgOperand(unsigned i) const
getArgOperand/setArgOperand - Return/set the i-th call argument.
VectorType - Class to represent vector types.
Definition: DerivedTypes.h:362
Class for arbitrary precision integers.
Definition: APInt.h:73
bool isIntegerTy() const
isIntegerTy - True if this is an instance of IntegerType.
Definition: Type.h:193
iterator_range< user_iterator > users()
Definition: Value.h:300
IntegerType * getInt8Ty()
Fetch the type representing an 8-bit integer.
Definition: IRBuilder.h:296
LLVM_ATTRIBUTE_UNUSED_RESULT 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:285
Value * CreateInsertValue(Value *Agg, Value *Val, ArrayRef< unsigned > Idxs, const Twine &Name="")
Definition: IRBuilder.h:1549
const Type * getScalarType() const LLVM_READONLY
getScalarType - If this is a vector type, return the element type, otherwise return 'this'...
Definition: Type.cpp:51
Value * CreateShl(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:823
INITIALIZE_PASS_BEGIN(SROA_DT,"scalarrepl","Scalar Replacement of Aggregates (DT)", false, false) INITIALIZE_PASS_END(SROA_DT
use_iterator use_begin()
Definition: Value.h:279
uint64_t MinAlign(uint64_t A, uint64_t B)
MinAlign - A and B are either alignments or offsets.
Definition: MathExtras.h:552
MemTransferInst - This class wraps the llvm.memcpy/memmove intrinsics.
const DataLayout & getDataLayout() const
Get the data layout for the module's target platform.
Definition: Module.cpp:372
static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout &DL)
tryToMakeAllocaBePromotable - This returns true if the alloca only has direct (non-volatile) loads an...
CallInst * CreateMemCpy(Value *Dst, Value *Src, uint64_t Size, unsigned Align, bool isVolatile=false, MDNode *TBAATag=nullptr, MDNode *TBAAStructTag=nullptr, MDNode *ScopeTag=nullptr, MDNode *NoAliasTag=nullptr)
Create and insert a memcpy between the specified pointers.
Definition: IRBuilder.h:383
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:239
DbgValueInst - This represents the llvm.dbg.value instruction.
unsigned getAlignment() const
getAlignment - Return the alignment of the access that is being performed
Definition: Instructions.h:243
void getAAMetadata(AAMDNodes &N, bool Merge=false) const
getAAMetadata - Fills the AAMDNodes structure with AA metadata from this instruction.
#define I(x, y, z)
Definition: MD5.cpp:54
TerminatorInst * getTerminator()
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:124
Scalar Replacement of false scalarrepl ssa
static bool isCompatibleAggregate(Type *T1, Type *T2)
isCompatibleAggregate - Check if T1 and T2 are either the same type or are "homogeneous" aggregates w...
static int const Threshold
TODO: Write a new FunctionPass AliasAnalysis so that it can keep a cache.
Scalar Replacement of false
bool use_empty() const
Definition: Value.h:275
user_iterator user_begin()
Definition: Value.h:294
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
getPrimitiveSizeInBits - Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:121
Module * getParent()
Get the module that this global value is contained inside of...
Definition: GlobalValue.h:365
bool isInstructionTriviallyDead(Instruction *I, const TargetLibraryInfo *TLI=nullptr)
isInstructionTriviallyDead - Return true if the result produced by the instruction is not used...
Definition: Local.cpp:282
Value * CreateTrunc(Value *V, Type *DestTy, const Twine &Name="")
Definition: IRBuilder.h:1189
LLVM Value Representation.
Definition: Value.h:69
void setAlignment(unsigned Align)
A vector that has set insertion semantics.
Definition: SetVector.h:37
DILocalVariable * getVariable() const
static VectorType * get(Type *ElementType, unsigned NumElements)
VectorType::get - This static method is the primary way to construct an VectorType.
Definition: Type.cpp:713
static bool isHomogeneousAggregate(Type *T, unsigned &NumElts, Type *&EltTy)
isHomogeneousAggregate - Check if type T is a struct or array containing elements of the same type (w...
void moveBefore(Instruction *MovePos)
moveBefore - Unlink this instruction from its current basic block and insert it into the basic block ...
Definition: Instruction.cpp:89
uint64_t getTypeSizeInBits(Type *Ty) const
Size examples:
Definition: DataLayout.h:507
#define DEBUG(X)
Definition: Debug.h:92
bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom, unsigned Align)
isSafeToLoadUnconditionally - Return true if we know that executing a load from this value cannot tra...
Definition: Loads.cpp:65
CallInst * CreateLifetimeStart(Value *Ptr, ConstantInt *Size=nullptr)
Create a lifetime.start intrinsic.
Definition: IRBuilder.cpp:164
bool isPowerOf2_32(uint32_t Value)
isPowerOf2_32 - This function returns true if the argument is a power of two > 0. ...
Definition: MathExtras.h:354
const Value * getFalseValue() const
Legacy analysis pass which computes a DominatorTree.
Definition: Dominators.h:203
unsigned getNumElements() const
Random access to the elements.
Definition: DerivedTypes.h:290
Type * getAllocatedType() const
getAllocatedType - Return the type that is being allocated by the instruction.
Definition: Instructions.h:122
bool isBigEndian() const
Definition: DataLayout.h:218
DbgDeclareInst - This represents the llvm.dbg.declare instruction.
Definition: IntrinsicInst.h:82
const BasicBlock * getParent() const
Definition: Instruction.h:72
#define T1
User * user_back()
Definition: Value.h:298
IntrinsicInst - A useful wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:37
AllocaInst - an instruction to allocate memory on the stack.
Definition: Instructions.h:76
gep_type_iterator gep_type_begin(const User *GEP)