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223e47cc LB |
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 | ||
223e47cc | 22 | #include "llvm/Transforms/Scalar.h" |
223e47cc LB |
23 | #include "llvm/ADT/SetVector.h" |
24 | #include "llvm/ADT/SmallVector.h" | |
25 | #include "llvm/ADT/Statistic.h" | |
85aaf69f | 26 | #include "llvm/Analysis/AssumptionCache.h" |
223e47cc LB |
27 | #include "llvm/Analysis/Loads.h" |
28 | #include "llvm/Analysis/ValueTracking.h" | |
1a4d82fc | 29 | #include "llvm/IR/CallSite.h" |
970d7e83 | 30 | #include "llvm/IR/Constants.h" |
1a4d82fc | 31 | #include "llvm/IR/DIBuilder.h" |
970d7e83 | 32 | #include "llvm/IR/DataLayout.h" |
1a4d82fc | 33 | #include "llvm/IR/DebugInfo.h" |
970d7e83 | 34 | #include "llvm/IR/DerivedTypes.h" |
1a4d82fc | 35 | #include "llvm/IR/Dominators.h" |
970d7e83 | 36 | #include "llvm/IR/Function.h" |
1a4d82fc | 37 | #include "llvm/IR/GetElementPtrTypeIterator.h" |
970d7e83 LB |
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" | |
223e47cc LB |
46 | #include "llvm/Support/Debug.h" |
47 | #include "llvm/Support/ErrorHandling.h" | |
223e47cc LB |
48 | #include "llvm/Support/MathExtras.h" |
49 | #include "llvm/Support/raw_ostream.h" | |
223e47cc LB |
50 | #include "llvm/Transforms/Utils/Local.h" |
51 | #include "llvm/Transforms/Utils/PromoteMemToReg.h" | |
52 | #include "llvm/Transforms/Utils/SSAUpdater.h" | |
53 | using namespace llvm; | |
54 | ||
1a4d82fc JJ |
55 | #define DEBUG_TYPE "scalarrepl" |
56 | ||
223e47cc LB |
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 | ||
1a4d82fc | 85 | bool runOnFunction(Function &F) override; |
223e47cc LB |
86 | |
87 | bool performScalarRepl(Function &F); | |
88 | bool performPromotion(Function &F); | |
89 | ||
90 | private: | |
91 | bool HasDomTree; | |
1a4d82fc | 92 | const DataLayout *DL; |
223e47cc LB |
93 | |
94 | /// DeadInsts - Keep track of instructions we have made dead, so that | |
95 | /// we can remove them after we are done working. | |
96 | SmallVector<Value*, 32> DeadInsts; | |
97 | ||
98 | /// AllocaInfo - When analyzing uses of an alloca instruction, this captures | |
99 | /// information about the uses. All these fields are initialized to false | |
100 | /// and set to true when something is learned. | |
101 | struct AllocaInfo { | |
102 | /// The alloca to promote. | |
103 | AllocaInst *AI; | |
104 | ||
105 | /// CheckedPHIs - This is a set of verified PHI nodes, to prevent infinite | |
106 | /// looping and avoid redundant work. | |
107 | SmallPtrSet<PHINode*, 8> CheckedPHIs; | |
108 | ||
109 | /// isUnsafe - This is set to true if the alloca cannot be SROA'd. | |
110 | bool isUnsafe : 1; | |
111 | ||
112 | /// isMemCpySrc - This is true if this aggregate is memcpy'd from. | |
113 | bool isMemCpySrc : 1; | |
114 | ||
115 | /// isMemCpyDst - This is true if this aggregate is memcpy'd into. | |
116 | bool isMemCpyDst : 1; | |
117 | ||
118 | /// hasSubelementAccess - This is true if a subelement of the alloca is | |
119 | /// ever accessed, or false if the alloca is only accessed with mem | |
120 | /// intrinsics or load/store that only access the entire alloca at once. | |
121 | bool hasSubelementAccess : 1; | |
122 | ||
123 | /// hasALoadOrStore - This is true if there are any loads or stores to it. | |
124 | /// The alloca may just be accessed with memcpy, for example, which would | |
125 | /// not set this. | |
126 | bool hasALoadOrStore : 1; | |
127 | ||
128 | explicit AllocaInfo(AllocaInst *ai) | |
129 | : AI(ai), isUnsafe(false), isMemCpySrc(false), isMemCpyDst(false), | |
130 | hasSubelementAccess(false), hasALoadOrStore(false) {} | |
131 | }; | |
132 | ||
133 | /// SRThreshold - The maximum alloca size to considered for SROA. | |
134 | unsigned SRThreshold; | |
135 | ||
136 | /// StructMemberThreshold - The maximum number of members a struct can | |
137 | /// contain to be considered for SROA. | |
138 | unsigned StructMemberThreshold; | |
139 | ||
140 | /// ArrayElementThreshold - The maximum number of elements an array can | |
141 | /// have to be considered for SROA. | |
142 | unsigned ArrayElementThreshold; | |
143 | ||
144 | /// ScalarLoadThreshold - The maximum size in bits of scalars to load when | |
145 | /// converting to scalar | |
146 | unsigned ScalarLoadThreshold; | |
147 | ||
148 | void MarkUnsafe(AllocaInfo &I, Instruction *User) { | |
149 | I.isUnsafe = true; | |
150 | DEBUG(dbgs() << " Transformation preventing inst: " << *User << '\n'); | |
151 | } | |
152 | ||
153 | bool isSafeAllocaToScalarRepl(AllocaInst *AI); | |
154 | ||
155 | void isSafeForScalarRepl(Instruction *I, uint64_t Offset, AllocaInfo &Info); | |
156 | void isSafePHISelectUseForScalarRepl(Instruction *User, uint64_t Offset, | |
157 | AllocaInfo &Info); | |
158 | void isSafeGEP(GetElementPtrInst *GEPI, uint64_t &Offset, AllocaInfo &Info); | |
159 | void isSafeMemAccess(uint64_t Offset, uint64_t MemSize, | |
160 | Type *MemOpType, bool isStore, AllocaInfo &Info, | |
161 | Instruction *TheAccess, bool AllowWholeAccess); | |
162 | bool TypeHasComponent(Type *T, uint64_t Offset, uint64_t Size); | |
163 | uint64_t FindElementAndOffset(Type *&T, uint64_t &Offset, | |
164 | Type *&IdxTy); | |
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, | |
1a4d82fc | 171 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc | 172 | void RewriteBitCast(BitCastInst *BC, AllocaInst *AI, uint64_t Offset, |
1a4d82fc | 173 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc | 174 | void RewriteGEP(GetElementPtrInst *GEPI, AllocaInst *AI, uint64_t Offset, |
1a4d82fc | 175 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc LB |
176 | void RewriteLifetimeIntrinsic(IntrinsicInst *II, AllocaInst *AI, |
177 | uint64_t Offset, | |
1a4d82fc | 178 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc LB |
179 | void RewriteMemIntrinUserOfAlloca(MemIntrinsic *MI, Instruction *Inst, |
180 | AllocaInst *AI, | |
1a4d82fc | 181 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc | 182 | void RewriteStoreUserOfWholeAlloca(StoreInst *SI, AllocaInst *AI, |
1a4d82fc | 183 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc | 184 | void RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI, |
1a4d82fc | 185 | SmallVectorImpl<AllocaInst *> &NewElts); |
223e47cc LB |
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) { | |
195 | initializeSROA_DTPass(*PassRegistry::getPassRegistry()); | |
196 | } | |
197 | ||
198 | // getAnalysisUsage - This pass does not require any passes, but we know it | |
199 | // will not alter the CFG, so say so. | |
1a4d82fc | 200 | void getAnalysisUsage(AnalysisUsage &AU) const override { |
85aaf69f | 201 | AU.addRequired<AssumptionCacheTracker>(); |
1a4d82fc | 202 | AU.addRequired<DominatorTreeWrapperPass>(); |
223e47cc LB |
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) { | |
213 | initializeSROA_SSAUpPass(*PassRegistry::getPassRegistry()); | |
214 | } | |
215 | ||
216 | // getAnalysisUsage - This pass does not require any passes, but we know it | |
217 | // will not alter the CFG, so say so. | |
1a4d82fc | 218 | void getAnalysisUsage(AnalysisUsage &AU) const override { |
85aaf69f | 219 | AU.addRequired<AssumptionCacheTracker>(); |
223e47cc LB |
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) | |
85aaf69f | 231 | INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) |
1a4d82fc | 232 | INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) |
223e47cc LB |
233 | INITIALIZE_PASS_END(SROA_DT, "scalarrepl", |
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) | |
85aaf69f | 238 | INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker) |
223e47cc LB |
239 | INITIALIZE_PASS_END(SROA_SSAUp, "scalarrepl-ssa", |
240 | "Scalar Replacement of Aggregates (SSAUp)", false, false) | |
241 | ||
242 | // Public interface to the ScalarReplAggregates pass | |
243 | FunctionPass *llvm::createScalarReplAggregatesPass(int Threshold, | |
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; | |
1a4d82fc | 267 | const DataLayout &DL; |
223e47cc LB |
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: | |
1a4d82fc | 310 | explicit ConvertToScalarInfo(unsigned Size, const DataLayout &DL, |
223e47cc | 311 | unsigned SLT) |
1a4d82fc JJ |
312 | : AllocaSize(Size), DL(DL), ScalarLoadThreshold(SLT), IsNotTrivial(false), |
313 | ScalarKind(Unknown), VectorTy(nullptr), HadNonMemTransferAccess(false), | |
223e47cc LB |
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. | |
1a4d82fc JJ |
341 | if (!CanConvertToScalar(AI, 0, nullptr) || !IsNotTrivial) |
342 | return nullptr; | |
223e47cc LB |
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) | |
1a4d82fc | 370 | return nullptr; |
223e47cc LB |
371 | |
372 | if ((ScalarKind == ImplicitVector || ScalarKind == Integer) && | |
1a4d82fc JJ |
373 | !HadNonMemTransferAccess && !DL.fitsInLegalInteger(BitWidth)) |
374 | return nullptr; | |
223e47cc LB |
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) | |
1a4d82fc | 379 | return nullptr; |
223e47cc LB |
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 | } | |
1a4d82fc JJ |
385 | AllocaInst *NewAI = new AllocaInst(NewTy, nullptr, "", |
386 | AI->getParent()->begin()); | |
387 | ConvertUsesToScalar(AI, NewAI, 0, nullptr); | |
223e47cc LB |
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 && | |
420 | isPowerOf2_32(In->getPrimitiveSizeInBits()))) { | |
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) { | |
1a4d82fc JJ |
476 | for (User *U : V->users()) { |
477 | Instruction *UI = cast<Instruction>(U); | |
223e47cc | 478 | |
1a4d82fc | 479 | if (LoadInst *LI = dyn_cast<LoadInst>(UI)) { |
223e47cc LB |
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 | ||
1a4d82fc | 491 | if (StoreInst *SI = dyn_cast<StoreInst>(UI)) { |
223e47cc LB |
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 | ||
1a4d82fc | 502 | if (BitCastInst *BCI = dyn_cast<BitCastInst>(UI)) { |
223e47cc LB |
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 | ||
1a4d82fc | 510 | if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(UI)) { |
223e47cc LB |
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()); | |
1a4d82fc | 518 | Value *GEPNonConstantIdx = nullptr; |
223e47cc LB |
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; | |
1a4d82fc | 530 | uint64_t GEPOffset = DL.getIndexedOffset(PtrTy, |
223e47cc LB |
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. | |
1a4d82fc | 542 | if (MemSetInst *MSI = dyn_cast<MemSetInst>(UI)) { |
223e47cc LB |
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. | |
1a4d82fc | 569 | if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(UI)) { |
223e47cc LB |
570 | // Store to dynamic index. |
571 | if (NonConstantIdx) | |
572 | return false; | |
573 | ConstantInt *Len = dyn_cast<ConstantInt>(MTI->getLength()); | |
1a4d82fc | 574 | if (!Len || Len->getZExtValue() != AllocaSize || Offset != 0) |
223e47cc LB |
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. | |
1a4d82fc | 582 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(UI)) { |
223e47cc LB |
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()) { | |
1a4d82fc | 607 | Instruction *User = cast<Instruction>(Ptr->user_back()); |
223e47cc LB |
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()); | |
1a4d82fc | 618 | Value* GEPNonConstantIdx = nullptr; |
223e47cc LB |
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; | |
1a4d82fc | 625 | uint64_t GEPOffset = DL.getIndexedOffset(GEP->getPointerOperandType(), |
223e47cc LB |
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), | |
1a4d82fc | 681 | Old, Offset, nullptr, Builder); |
223e47cc LB |
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. | |
1a4d82fc | 702 | AllocaInst *OrigAI = cast<AllocaInst>(GetUnderlyingObject(Ptr, &DL, 0)); |
223e47cc | 703 | |
1a4d82fc | 704 | if (GetUnderlyingObject(MTI->getSource(), &DL, 0) != OrigAI) { |
223e47cc LB |
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); | |
1a4d82fc | 720 | } else if (GetUnderlyingObject(MTI->getDest(), &DL, 0) != OrigAI) { |
223e47cc LB |
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)) { | |
1a4d82fc JJ |
780 | unsigned FromTypeSize = DL.getTypeAllocSize(FromType); |
781 | unsigned ToTypeSize = DL.getTypeAllocSize(ToType); | |
223e47cc LB |
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) { | |
1a4d82fc | 788 | unsigned EltSize = DL.getTypeAllocSizeInBits(VTy->getElementType()); |
223e47cc LB |
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"); | |
1a4d82fc | 814 | const StructLayout &Layout = *DL.getStructLayout(ST); |
223e47cc LB |
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), | |
1a4d82fc | 819 | nullptr, Builder); |
223e47cc LB |
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"); | |
1a4d82fc | 828 | uint64_t EltSize = DL.getTypeAllocSizeInBits(AT->getElementType()); |
223e47cc LB |
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(), | |
1a4d82fc JJ |
832 | Offset+i*EltSize, nullptr, |
833 | Builder); | |
223e47cc LB |
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; | |
1a4d82fc | 845 | if (DL.isBigEndian()) { |
223e47cc LB |
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. | |
1a4d82fc JJ |
849 | ShAmt = DL.getTypeStoreSizeInBits(NTy) - |
850 | DL.getTypeStoreSizeInBits(ToType) - Offset; | |
223e47cc LB |
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. | |
1a4d82fc | 866 | unsigned LIBitWidth = DL.getTypeSizeInBits(ToType); |
223e47cc LB |
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)) { | |
1a4d82fc JJ |
913 | uint64_t VecSize = DL.getTypeAllocSizeInBits(VTy); |
914 | uint64_t ValSize = DL.getTypeAllocSizeInBits(SV->getType()); | |
223e47cc LB |
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); | |
1a4d82fc | 925 | uint64_t EltSize = DL.getTypeAllocSizeInBits(EltTy); |
223e47cc LB |
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"); | |
1a4d82fc | 944 | const StructLayout &Layout = *DL.getStructLayout(ST); |
223e47cc LB |
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), | |
1a4d82fc | 949 | nullptr, Builder); |
223e47cc LB |
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"); | |
1a4d82fc | 957 | uint64_t EltSize = DL.getTypeAllocSizeInBits(AT->getElementType()); |
223e47cc LB |
958 | for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) { |
959 | Value *Elt = Builder.CreateExtractValue(SV, i); | |
1a4d82fc JJ |
960 | Old = ConvertScalar_InsertValue(Elt, Old, Offset+i*EltSize, nullptr, |
961 | Builder); | |
223e47cc LB |
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. | |
1a4d82fc JJ |
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); | |
223e47cc LB |
972 | if (SV->getType()->isFloatingPointTy() || SV->getType()->isVectorTy()) |
973 | SV = Builder.CreateBitCast(SV, IntegerType::get(SV->getContext(),SrcWidth)); | |
974 | else if (SV->getType()->isPointerTy()) | |
1a4d82fc | 975 | SV = Builder.CreatePtrToInt(SV, DL.getIntPtrType(SV->getType())); |
223e47cc LB |
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; | |
1a4d82fc | 994 | if (DL.isBigEndian()) { |
223e47cc LB |
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) { | |
1a4d82fc JJ |
1032 | if (skipOptnoneFunction(F)) |
1033 | return false; | |
1034 | ||
1035 | DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); | |
1036 | DL = DLP ? &DLP->getDataLayout() : nullptr; | |
223e47cc LB |
1037 | |
1038 | bool Changed = performPromotion(F); | |
1039 | ||
970d7e83 | 1040 | // FIXME: ScalarRepl currently depends on DataLayout more than it |
223e47cc LB |
1041 | // theoretically needs to. It should be refactored in order to support |
1042 | // target-independent IR. Until this is done, just skip the actual | |
1043 | // scalar-replacement portion of this pass. | |
1a4d82fc | 1044 | if (!DL) return Changed; |
223e47cc LB |
1045 | |
1046 | while (1) { | |
1047 | bool LocalChange = performScalarRepl(F); | |
1048 | if (!LocalChange) break; // No need to repromote if no scalarrepl | |
1049 | Changed = true; | |
1050 | LocalChange = performPromotion(F); | |
1051 | if (!LocalChange) break; // No need to re-scalarrepl if no promotion | |
1052 | } | |
1053 | ||
1054 | return Changed; | |
1055 | } | |
1056 | ||
1057 | namespace { | |
1058 | class AllocaPromoter : public LoadAndStorePromoter { | |
1059 | AllocaInst *AI; | |
1060 | DIBuilder *DIB; | |
1061 | SmallVector<DbgDeclareInst *, 4> DDIs; | |
1062 | SmallVector<DbgValueInst *, 4> DVIs; | |
1063 | public: | |
1064 | AllocaPromoter(const SmallVectorImpl<Instruction*> &Insts, SSAUpdater &S, | |
1065 | DIBuilder *DB) | |
1a4d82fc | 1066 | : LoadAndStorePromoter(Insts, S), AI(nullptr), DIB(DB) {} |
223e47cc LB |
1067 | |
1068 | void run(AllocaInst *AI, const SmallVectorImpl<Instruction*> &Insts) { | |
1069 | // Remember which alloca we're promoting (for isInstInList). | |
1070 | this->AI = AI; | |
85aaf69f SL |
1071 | if (auto *L = LocalAsMetadata::getIfExists(AI)) { |
1072 | if (auto *DebugNode = MetadataAsValue::getIfExists(AI->getContext(), L)) { | |
1073 | for (User *U : DebugNode->users()) | |
1074 | if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(U)) | |
1075 | DDIs.push_back(DDI); | |
1076 | else if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(U)) | |
1077 | DVIs.push_back(DVI); | |
1078 | } | |
223e47cc LB |
1079 | } |
1080 | ||
1081 | LoadAndStorePromoter::run(Insts); | |
1082 | AI->eraseFromParent(); | |
1a4d82fc | 1083 | for (SmallVectorImpl<DbgDeclareInst *>::iterator I = DDIs.begin(), |
223e47cc LB |
1084 | E = DDIs.end(); I != E; ++I) { |
1085 | DbgDeclareInst *DDI = *I; | |
1086 | DDI->eraseFromParent(); | |
1087 | } | |
1a4d82fc | 1088 | for (SmallVectorImpl<DbgValueInst *>::iterator I = DVIs.begin(), |
223e47cc LB |
1089 | E = DVIs.end(); I != E; ++I) { |
1090 | DbgValueInst *DVI = *I; | |
1091 | DVI->eraseFromParent(); | |
1092 | } | |
1093 | } | |
1094 | ||
1a4d82fc JJ |
1095 | bool isInstInList(Instruction *I, |
1096 | const SmallVectorImpl<Instruction*> &Insts) const override { | |
223e47cc LB |
1097 | if (LoadInst *LI = dyn_cast<LoadInst>(I)) |
1098 | return LI->getOperand(0) == AI; | |
1099 | return cast<StoreInst>(I)->getPointerOperand() == AI; | |
1100 | } | |
1101 | ||
1a4d82fc JJ |
1102 | void updateDebugInfo(Instruction *Inst) const override { |
1103 | for (SmallVectorImpl<DbgDeclareInst *>::const_iterator I = DDIs.begin(), | |
223e47cc LB |
1104 | E = DDIs.end(); I != E; ++I) { |
1105 | DbgDeclareInst *DDI = *I; | |
1106 | if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) | |
1107 | ConvertDebugDeclareToDebugValue(DDI, SI, *DIB); | |
1108 | else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) | |
1109 | ConvertDebugDeclareToDebugValue(DDI, LI, *DIB); | |
1110 | } | |
1a4d82fc | 1111 | for (SmallVectorImpl<DbgValueInst *>::const_iterator I = DVIs.begin(), |
223e47cc LB |
1112 | E = DVIs.end(); I != E; ++I) { |
1113 | DbgValueInst *DVI = *I; | |
1a4d82fc | 1114 | Value *Arg = nullptr; |
223e47cc LB |
1115 | if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) { |
1116 | // If an argument is zero extended then use argument directly. The ZExt | |
1117 | // may be zapped by an optimization pass in future. | |
1118 | if (ZExtInst *ZExt = dyn_cast<ZExtInst>(SI->getOperand(0))) | |
1119 | Arg = dyn_cast<Argument>(ZExt->getOperand(0)); | |
1120 | if (SExtInst *SExt = dyn_cast<SExtInst>(SI->getOperand(0))) | |
1121 | Arg = dyn_cast<Argument>(SExt->getOperand(0)); | |
1122 | if (!Arg) | |
1123 | Arg = SI->getOperand(0); | |
1124 | } else if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) { | |
1125 | Arg = LI->getOperand(0); | |
1126 | } else { | |
1127 | continue; | |
1128 | } | |
85aaf69f SL |
1129 | Instruction *DbgVal = DIB->insertDbgValueIntrinsic( |
1130 | Arg, 0, DIVariable(DVI->getVariable()), | |
1131 | DIExpression(DVI->getExpression()), Inst); | |
223e47cc LB |
1132 | DbgVal->setDebugLoc(DVI->getDebugLoc()); |
1133 | } | |
1134 | } | |
1135 | }; | |
1136 | } // end anon namespace | |
1137 | ||
1138 | /// isSafeSelectToSpeculate - Select instructions that use an alloca and are | |
1139 | /// subsequently loaded can be rewritten to load both input pointers and then | |
1140 | /// select between the result, allowing the load of the alloca to be promoted. | |
1141 | /// From this: | |
1142 | /// %P2 = select i1 %cond, i32* %Alloca, i32* %Other | |
1143 | /// %V = load i32* %P2 | |
1144 | /// to: | |
1145 | /// %V1 = load i32* %Alloca -> will be mem2reg'd | |
1146 | /// %V2 = load i32* %Other | |
1147 | /// %V = select i1 %cond, i32 %V1, i32 %V2 | |
1148 | /// | |
1149 | /// We can do this to a select if its only uses are loads and if the operand to | |
1150 | /// the select can be loaded unconditionally. | |
1a4d82fc JJ |
1151 | static bool isSafeSelectToSpeculate(SelectInst *SI, const DataLayout *DL) { |
1152 | bool TDerefable = SI->getTrueValue()->isDereferenceablePointer(DL); | |
1153 | bool FDerefable = SI->getFalseValue()->isDereferenceablePointer(DL); | |
223e47cc | 1154 | |
1a4d82fc JJ |
1155 | for (User *U : SI->users()) { |
1156 | LoadInst *LI = dyn_cast<LoadInst>(U); | |
1157 | if (!LI || !LI->isSimple()) return false; | |
223e47cc LB |
1158 | |
1159 | // Both operands to the select need to be dereferencable, either absolutely | |
1160 | // (e.g. allocas) or at this point because we can see other accesses to it. | |
1161 | if (!TDerefable && !isSafeToLoadUnconditionally(SI->getTrueValue(), LI, | |
1a4d82fc | 1162 | LI->getAlignment(), DL)) |
223e47cc LB |
1163 | return false; |
1164 | if (!FDerefable && !isSafeToLoadUnconditionally(SI->getFalseValue(), LI, | |
1a4d82fc | 1165 | LI->getAlignment(), DL)) |
223e47cc LB |
1166 | return false; |
1167 | } | |
1168 | ||
1169 | return true; | |
1170 | } | |
1171 | ||
1172 | /// isSafePHIToSpeculate - PHI instructions that use an alloca and are | |
1173 | /// subsequently loaded can be rewritten to load both input pointers in the pred | |
1174 | /// blocks and then PHI the results, allowing the load of the alloca to be | |
1175 | /// promoted. | |
1176 | /// From this: | |
1177 | /// %P2 = phi [i32* %Alloca, i32* %Other] | |
1178 | /// %V = load i32* %P2 | |
1179 | /// to: | |
1180 | /// %V1 = load i32* %Alloca -> will be mem2reg'd | |
1181 | /// ... | |
1182 | /// %V2 = load i32* %Other | |
1183 | /// ... | |
1184 | /// %V = phi [i32 %V1, i32 %V2] | |
1185 | /// | |
1186 | /// We can do this to a select if its only uses are loads and if the operand to | |
1187 | /// the select can be loaded unconditionally. | |
1a4d82fc | 1188 | static bool isSafePHIToSpeculate(PHINode *PN, const DataLayout *DL) { |
223e47cc LB |
1189 | // For now, we can only do this promotion if the load is in the same block as |
1190 | // the PHI, and if there are no stores between the phi and load. | |
1191 | // TODO: Allow recursive phi users. | |
1192 | // TODO: Allow stores. | |
1193 | BasicBlock *BB = PN->getParent(); | |
1194 | unsigned MaxAlign = 0; | |
1a4d82fc JJ |
1195 | for (User *U : PN->users()) { |
1196 | LoadInst *LI = dyn_cast<LoadInst>(U); | |
1197 | if (!LI || !LI->isSimple()) return false; | |
223e47cc LB |
1198 | |
1199 | // For now we only allow loads in the same block as the PHI. This is a | |
1200 | // common case that happens when instcombine merges two loads through a PHI. | |
1201 | if (LI->getParent() != BB) return false; | |
1202 | ||
1203 | // Ensure that there are no instructions between the PHI and the load that | |
1204 | // could store. | |
1205 | for (BasicBlock::iterator BBI = PN; &*BBI != LI; ++BBI) | |
1206 | if (BBI->mayWriteToMemory()) | |
1207 | return false; | |
1208 | ||
1209 | MaxAlign = std::max(MaxAlign, LI->getAlignment()); | |
1210 | } | |
1211 | ||
1212 | // Okay, we know that we have one or more loads in the same block as the PHI. | |
1213 | // We can transform this if it is safe to push the loads into the predecessor | |
1214 | // blocks. The only thing to watch out for is that we can't put a possibly | |
1215 | // trapping load in the predecessor if it is a critical edge. | |
1216 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |
1217 | BasicBlock *Pred = PN->getIncomingBlock(i); | |
1218 | Value *InVal = PN->getIncomingValue(i); | |
1219 | ||
1220 | // If the terminator of the predecessor has side-effects (an invoke), | |
1221 | // there is no safe place to put a load in the predecessor. | |
1222 | if (Pred->getTerminator()->mayHaveSideEffects()) | |
1223 | return false; | |
1224 | ||
1225 | // If the value is produced by the terminator of the predecessor | |
1226 | // (an invoke), there is no valid place to put a load in the predecessor. | |
1227 | if (Pred->getTerminator() == InVal) | |
1228 | return false; | |
1229 | ||
1230 | // If the predecessor has a single successor, then the edge isn't critical. | |
1231 | if (Pred->getTerminator()->getNumSuccessors() == 1) | |
1232 | continue; | |
1233 | ||
1234 | // If this pointer is always safe to load, or if we can prove that there is | |
1235 | // already a load in the block, then we can move the load to the pred block. | |
1a4d82fc JJ |
1236 | if (InVal->isDereferenceablePointer(DL) || |
1237 | isSafeToLoadUnconditionally(InVal, Pred->getTerminator(), MaxAlign, DL)) | |
223e47cc LB |
1238 | continue; |
1239 | ||
1240 | return false; | |
1241 | } | |
1242 | ||
1243 | return true; | |
1244 | } | |
1245 | ||
1246 | ||
1247 | /// tryToMakeAllocaBePromotable - This returns true if the alloca only has | |
1248 | /// direct (non-volatile) loads and stores to it. If the alloca is close but | |
1249 | /// not quite there, this will transform the code to allow promotion. As such, | |
1250 | /// it is a non-pure predicate. | |
1a4d82fc | 1251 | static bool tryToMakeAllocaBePromotable(AllocaInst *AI, const DataLayout *DL) { |
223e47cc LB |
1252 | SetVector<Instruction*, SmallVector<Instruction*, 4>, |
1253 | SmallPtrSet<Instruction*, 4> > InstsToRewrite; | |
1a4d82fc | 1254 | for (User *U : AI->users()) { |
223e47cc LB |
1255 | if (LoadInst *LI = dyn_cast<LoadInst>(U)) { |
1256 | if (!LI->isSimple()) | |
1257 | return false; | |
1258 | continue; | |
1259 | } | |
1260 | ||
1261 | if (StoreInst *SI = dyn_cast<StoreInst>(U)) { | |
1262 | if (SI->getOperand(0) == AI || !SI->isSimple()) | |
1263 | return false; // Don't allow a store OF the AI, only INTO the AI. | |
1264 | continue; | |
1265 | } | |
1266 | ||
1267 | if (SelectInst *SI = dyn_cast<SelectInst>(U)) { | |
1268 | // If the condition being selected on is a constant, fold the select, yes | |
1269 | // this does (rarely) happen early on. | |
1270 | if (ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition())) { | |
1271 | Value *Result = SI->getOperand(1+CI->isZero()); | |
1272 | SI->replaceAllUsesWith(Result); | |
1273 | SI->eraseFromParent(); | |
1274 | ||
1275 | // This is very rare and we just scrambled the use list of AI, start | |
1276 | // over completely. | |
1a4d82fc | 1277 | return tryToMakeAllocaBePromotable(AI, DL); |
223e47cc LB |
1278 | } |
1279 | ||
1280 | // If it is safe to turn "load (select c, AI, ptr)" into a select of two | |
1281 | // loads, then we can transform this by rewriting the select. | |
1a4d82fc | 1282 | if (!isSafeSelectToSpeculate(SI, DL)) |
223e47cc LB |
1283 | return false; |
1284 | ||
1285 | InstsToRewrite.insert(SI); | |
1286 | continue; | |
1287 | } | |
1288 | ||
1289 | if (PHINode *PN = dyn_cast<PHINode>(U)) { | |
1290 | if (PN->use_empty()) { // Dead PHIs can be stripped. | |
1291 | InstsToRewrite.insert(PN); | |
1292 | continue; | |
1293 | } | |
1294 | ||
1295 | // If it is safe to turn "load (phi [AI, ptr, ...])" into a PHI of loads | |
1296 | // in the pred blocks, then we can transform this by rewriting the PHI. | |
1a4d82fc | 1297 | if (!isSafePHIToSpeculate(PN, DL)) |
223e47cc LB |
1298 | return false; |
1299 | ||
1300 | InstsToRewrite.insert(PN); | |
1301 | continue; | |
1302 | } | |
1303 | ||
1304 | if (BitCastInst *BCI = dyn_cast<BitCastInst>(U)) { | |
1305 | if (onlyUsedByLifetimeMarkers(BCI)) { | |
1306 | InstsToRewrite.insert(BCI); | |
1307 | continue; | |
1308 | } | |
1309 | } | |
1310 | ||
1311 | return false; | |
1312 | } | |
1313 | ||
1314 | // If there are no instructions to rewrite, then all uses are load/stores and | |
1315 | // we're done! | |
1316 | if (InstsToRewrite.empty()) | |
1317 | return true; | |
1318 | ||
1319 | // If we have instructions that need to be rewritten for this to be promotable | |
1320 | // take care of it now. | |
1321 | for (unsigned i = 0, e = InstsToRewrite.size(); i != e; ++i) { | |
1322 | if (BitCastInst *BCI = dyn_cast<BitCastInst>(InstsToRewrite[i])) { | |
1323 | // This could only be a bitcast used by nothing but lifetime intrinsics. | |
1a4d82fc JJ |
1324 | for (BitCastInst::user_iterator I = BCI->user_begin(), E = BCI->user_end(); |
1325 | I != E;) | |
1326 | cast<Instruction>(*I++)->eraseFromParent(); | |
223e47cc LB |
1327 | BCI->eraseFromParent(); |
1328 | continue; | |
1329 | } | |
1330 | ||
1331 | if (SelectInst *SI = dyn_cast<SelectInst>(InstsToRewrite[i])) { | |
1332 | // Selects in InstsToRewrite only have load uses. Rewrite each as two | |
1333 | // loads with a new select. | |
1334 | while (!SI->use_empty()) { | |
1a4d82fc | 1335 | LoadInst *LI = cast<LoadInst>(SI->user_back()); |
223e47cc LB |
1336 | |
1337 | IRBuilder<> Builder(LI); | |
1338 | LoadInst *TrueLoad = | |
1339 | Builder.CreateLoad(SI->getTrueValue(), LI->getName()+".t"); | |
1340 | LoadInst *FalseLoad = | |
1341 | Builder.CreateLoad(SI->getFalseValue(), LI->getName()+".f"); | |
1342 | ||
1a4d82fc | 1343 | // Transfer alignment and AA info if present. |
223e47cc LB |
1344 | TrueLoad->setAlignment(LI->getAlignment()); |
1345 | FalseLoad->setAlignment(LI->getAlignment()); | |
1a4d82fc JJ |
1346 | |
1347 | AAMDNodes Tags; | |
1348 | LI->getAAMetadata(Tags); | |
1349 | if (Tags) { | |
1350 | TrueLoad->setAAMetadata(Tags); | |
1351 | FalseLoad->setAAMetadata(Tags); | |
223e47cc LB |
1352 | } |
1353 | ||
1354 | Value *V = Builder.CreateSelect(SI->getCondition(), TrueLoad, FalseLoad); | |
1355 | V->takeName(LI); | |
1356 | LI->replaceAllUsesWith(V); | |
1357 | LI->eraseFromParent(); | |
1358 | } | |
1359 | ||
1360 | // Now that all the loads are gone, the select is gone too. | |
1361 | SI->eraseFromParent(); | |
1362 | continue; | |
1363 | } | |
1364 | ||
1365 | // Otherwise, we have a PHI node which allows us to push the loads into the | |
1366 | // predecessors. | |
1367 | PHINode *PN = cast<PHINode>(InstsToRewrite[i]); | |
1368 | if (PN->use_empty()) { | |
1369 | PN->eraseFromParent(); | |
1370 | continue; | |
1371 | } | |
1372 | ||
1373 | Type *LoadTy = cast<PointerType>(PN->getType())->getElementType(); | |
1374 | PHINode *NewPN = PHINode::Create(LoadTy, PN->getNumIncomingValues(), | |
1375 | PN->getName()+".ld", PN); | |
1376 | ||
1a4d82fc | 1377 | // Get the AA tags and alignment to use from one of the loads. It doesn't |
223e47cc | 1378 | // matter which one we get and if any differ, it doesn't matter. |
1a4d82fc JJ |
1379 | LoadInst *SomeLoad = cast<LoadInst>(PN->user_back()); |
1380 | ||
1381 | AAMDNodes AATags; | |
1382 | SomeLoad->getAAMetadata(AATags); | |
223e47cc LB |
1383 | unsigned Align = SomeLoad->getAlignment(); |
1384 | ||
1385 | // Rewrite all loads of the PN to use the new PHI. | |
1386 | while (!PN->use_empty()) { | |
1a4d82fc | 1387 | LoadInst *LI = cast<LoadInst>(PN->user_back()); |
223e47cc LB |
1388 | LI->replaceAllUsesWith(NewPN); |
1389 | LI->eraseFromParent(); | |
1390 | } | |
1391 | ||
1392 | // Inject loads into all of the pred blocks. Keep track of which blocks we | |
1393 | // insert them into in case we have multiple edges from the same block. | |
1394 | DenseMap<BasicBlock*, LoadInst*> InsertedLoads; | |
1395 | ||
1396 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |
1397 | BasicBlock *Pred = PN->getIncomingBlock(i); | |
1398 | LoadInst *&Load = InsertedLoads[Pred]; | |
1a4d82fc | 1399 | if (!Load) { |
223e47cc LB |
1400 | Load = new LoadInst(PN->getIncomingValue(i), |
1401 | PN->getName() + "." + Pred->getName(), | |
1402 | Pred->getTerminator()); | |
1403 | Load->setAlignment(Align); | |
1a4d82fc | 1404 | if (AATags) Load->setAAMetadata(AATags); |
223e47cc LB |
1405 | } |
1406 | ||
1407 | NewPN->addIncoming(Load, Pred); | |
1408 | } | |
1409 | ||
1410 | PN->eraseFromParent(); | |
1411 | } | |
1412 | ||
1413 | ++NumAdjusted; | |
1414 | return true; | |
1415 | } | |
1416 | ||
1417 | bool SROA::performPromotion(Function &F) { | |
1418 | std::vector<AllocaInst*> Allocas; | |
1a4d82fc | 1419 | DominatorTree *DT = nullptr; |
223e47cc | 1420 | if (HasDomTree) |
1a4d82fc | 1421 | DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); |
85aaf69f SL |
1422 | AssumptionCache &AC = |
1423 | getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F); | |
223e47cc LB |
1424 | |
1425 | BasicBlock &BB = F.getEntryBlock(); // Get the entry node for the function | |
85aaf69f | 1426 | DIBuilder DIB(*F.getParent(), /*AllowUnresolved*/ false); |
223e47cc LB |
1427 | bool Changed = false; |
1428 | SmallVector<Instruction*, 64> Insts; | |
1429 | while (1) { | |
1430 | Allocas.clear(); | |
1431 | ||
1432 | // Find allocas that are safe to promote, by looking at all instructions in | |
1433 | // the entry node | |
1434 | for (BasicBlock::iterator I = BB.begin(), E = --BB.end(); I != E; ++I) | |
1435 | if (AllocaInst *AI = dyn_cast<AllocaInst>(I)) // Is it an alloca? | |
1a4d82fc | 1436 | if (tryToMakeAllocaBePromotable(AI, DL)) |
223e47cc LB |
1437 | Allocas.push_back(AI); |
1438 | ||
1439 | if (Allocas.empty()) break; | |
1440 | ||
1441 | if (HasDomTree) | |
85aaf69f | 1442 | PromoteMemToReg(Allocas, *DT, nullptr, &AC); |
223e47cc LB |
1443 | else { |
1444 | SSAUpdater SSA; | |
1445 | for (unsigned i = 0, e = Allocas.size(); i != e; ++i) { | |
1446 | AllocaInst *AI = Allocas[i]; | |
1447 | ||
1448 | // Build list of instructions to promote. | |
1a4d82fc JJ |
1449 | for (User *U : AI->users()) |
1450 | Insts.push_back(cast<Instruction>(U)); | |
223e47cc LB |
1451 | AllocaPromoter(Insts, SSA, &DIB).run(AI, Insts); |
1452 | Insts.clear(); | |
1453 | } | |
1454 | } | |
1455 | NumPromoted += Allocas.size(); | |
1456 | Changed = true; | |
1457 | } | |
1458 | ||
1459 | return Changed; | |
1460 | } | |
1461 | ||
1462 | ||
1463 | /// ShouldAttemptScalarRepl - Decide if an alloca is a good candidate for | |
1464 | /// SROA. It must be a struct or array type with a small number of elements. | |
1465 | bool SROA::ShouldAttemptScalarRepl(AllocaInst *AI) { | |
1466 | Type *T = AI->getAllocatedType(); | |
1467 | // Do not promote any struct that has too many members. | |
1468 | if (StructType *ST = dyn_cast<StructType>(T)) | |
1469 | return ST->getNumElements() <= StructMemberThreshold; | |
1470 | // Do not promote any array that has too many elements. | |
1471 | if (ArrayType *AT = dyn_cast<ArrayType>(T)) | |
1472 | return AT->getNumElements() <= ArrayElementThreshold; | |
1473 | return false; | |
1474 | } | |
1475 | ||
1476 | // performScalarRepl - This algorithm is a simple worklist driven algorithm, | |
1a4d82fc JJ |
1477 | // which runs on all of the alloca instructions in the entry block, removing |
1478 | // them if they are only used by getelementptr instructions. | |
223e47cc LB |
1479 | // |
1480 | bool SROA::performScalarRepl(Function &F) { | |
1481 | std::vector<AllocaInst*> WorkList; | |
1482 | ||
1483 | // Scan the entry basic block, adding allocas to the worklist. | |
1484 | BasicBlock &BB = F.getEntryBlock(); | |
1485 | for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ++I) | |
1486 | if (AllocaInst *A = dyn_cast<AllocaInst>(I)) | |
1487 | WorkList.push_back(A); | |
1488 | ||
1489 | // Process the worklist | |
1490 | bool Changed = false; | |
1491 | while (!WorkList.empty()) { | |
1492 | AllocaInst *AI = WorkList.back(); | |
1493 | WorkList.pop_back(); | |
1494 | ||
1495 | // Handle dead allocas trivially. These can be formed by SROA'ing arrays | |
1496 | // with unused elements. | |
1497 | if (AI->use_empty()) { | |
1498 | AI->eraseFromParent(); | |
1499 | Changed = true; | |
1500 | continue; | |
1501 | } | |
1502 | ||
1503 | // If this alloca is impossible for us to promote, reject it early. | |
1504 | if (AI->isArrayAllocation() || !AI->getAllocatedType()->isSized()) | |
1505 | continue; | |
1506 | ||
1507 | // Check to see if we can perform the core SROA transformation. We cannot | |
1508 | // transform the allocation instruction if it is an array allocation | |
1509 | // (allocations OF arrays are ok though), and an allocation of a scalar | |
1510 | // value cannot be decomposed at all. | |
1a4d82fc | 1511 | uint64_t AllocaSize = DL->getTypeAllocSize(AI->getAllocatedType()); |
223e47cc LB |
1512 | |
1513 | // Do not promote [0 x %struct]. | |
1514 | if (AllocaSize == 0) continue; | |
1515 | ||
1516 | // Do not promote any struct whose size is too big. | |
1517 | if (AllocaSize > SRThreshold) continue; | |
1518 | ||
1519 | // If the alloca looks like a good candidate for scalar replacement, and if | |
1520 | // all its users can be transformed, then split up the aggregate into its | |
1521 | // separate elements. | |
1522 | if (ShouldAttemptScalarRepl(AI) && isSafeAllocaToScalarRepl(AI)) { | |
1523 | DoScalarReplacement(AI, WorkList); | |
1524 | Changed = true; | |
1525 | continue; | |
1526 | } | |
1527 | ||
1528 | // If we can turn this aggregate value (potentially with casts) into a | |
1529 | // simple scalar value that can be mem2reg'd into a register value. | |
1530 | // IsNotTrivial tracks whether this is something that mem2reg could have | |
1531 | // promoted itself. If so, we don't want to transform it needlessly. Note | |
1532 | // that we can't just check based on the type: the alloca may be of an i32 | |
1533 | // but that has pointer arithmetic to set byte 3 of it or something. | |
1534 | if (AllocaInst *NewAI = ConvertToScalarInfo( | |
1a4d82fc | 1535 | (unsigned)AllocaSize, *DL, ScalarLoadThreshold).TryConvert(AI)) { |
223e47cc LB |
1536 | NewAI->takeName(AI); |
1537 | AI->eraseFromParent(); | |
1538 | ++NumConverted; | |
1539 | Changed = true; | |
1540 | continue; | |
1541 | } | |
1542 | ||
1543 | // Otherwise, couldn't process this alloca. | |
1544 | } | |
1545 | ||
1546 | return Changed; | |
1547 | } | |
1548 | ||
1549 | /// DoScalarReplacement - This alloca satisfied the isSafeAllocaToScalarRepl | |
1550 | /// predicate, do SROA now. | |
1551 | void SROA::DoScalarReplacement(AllocaInst *AI, | |
1552 | std::vector<AllocaInst*> &WorkList) { | |
1553 | DEBUG(dbgs() << "Found inst to SROA: " << *AI << '\n'); | |
1554 | SmallVector<AllocaInst*, 32> ElementAllocas; | |
1555 | if (StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) { | |
1556 | ElementAllocas.reserve(ST->getNumContainedTypes()); | |
1557 | for (unsigned i = 0, e = ST->getNumContainedTypes(); i != e; ++i) { | |
1a4d82fc | 1558 | AllocaInst *NA = new AllocaInst(ST->getContainedType(i), nullptr, |
223e47cc LB |
1559 | AI->getAlignment(), |
1560 | AI->getName() + "." + Twine(i), AI); | |
1561 | ElementAllocas.push_back(NA); | |
1562 | WorkList.push_back(NA); // Add to worklist for recursive processing | |
1563 | } | |
1564 | } else { | |
1565 | ArrayType *AT = cast<ArrayType>(AI->getAllocatedType()); | |
1566 | ElementAllocas.reserve(AT->getNumElements()); | |
1567 | Type *ElTy = AT->getElementType(); | |
1568 | for (unsigned i = 0, e = AT->getNumElements(); i != e; ++i) { | |
1a4d82fc | 1569 | AllocaInst *NA = new AllocaInst(ElTy, nullptr, AI->getAlignment(), |
223e47cc LB |
1570 | AI->getName() + "." + Twine(i), AI); |
1571 | ElementAllocas.push_back(NA); | |
1572 | WorkList.push_back(NA); // Add to worklist for recursive processing | |
1573 | } | |
1574 | } | |
1575 | ||
1576 | // Now that we have created the new alloca instructions, rewrite all the | |
1577 | // uses of the old alloca. | |
1578 | RewriteForScalarRepl(AI, AI, 0, ElementAllocas); | |
1579 | ||
1580 | // Now erase any instructions that were made dead while rewriting the alloca. | |
1581 | DeleteDeadInstructions(); | |
1582 | AI->eraseFromParent(); | |
1583 | ||
1584 | ++NumReplaced; | |
1585 | } | |
1586 | ||
1587 | /// DeleteDeadInstructions - Erase instructions on the DeadInstrs list, | |
1588 | /// recursively including all their operands that become trivially dead. | |
1589 | void SROA::DeleteDeadInstructions() { | |
1590 | while (!DeadInsts.empty()) { | |
1591 | Instruction *I = cast<Instruction>(DeadInsts.pop_back_val()); | |
1592 | ||
1593 | for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI) | |
1594 | if (Instruction *U = dyn_cast<Instruction>(*OI)) { | |
1595 | // Zero out the operand and see if it becomes trivially dead. | |
1596 | // (But, don't add allocas to the dead instruction list -- they are | |
1597 | // already on the worklist and will be deleted separately.) | |
1a4d82fc | 1598 | *OI = nullptr; |
223e47cc LB |
1599 | if (isInstructionTriviallyDead(U) && !isa<AllocaInst>(U)) |
1600 | DeadInsts.push_back(U); | |
1601 | } | |
1602 | ||
1603 | I->eraseFromParent(); | |
1604 | } | |
1605 | } | |
1606 | ||
1607 | /// isSafeForScalarRepl - Check if instruction I is a safe use with regard to | |
1608 | /// performing scalar replacement of alloca AI. The results are flagged in | |
1609 | /// the Info parameter. Offset indicates the position within AI that is | |
1610 | /// referenced by this instruction. | |
1611 | void SROA::isSafeForScalarRepl(Instruction *I, uint64_t Offset, | |
1612 | AllocaInfo &Info) { | |
1a4d82fc JJ |
1613 | for (Use &U : I->uses()) { |
1614 | Instruction *User = cast<Instruction>(U.getUser()); | |
223e47cc LB |
1615 | |
1616 | if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) { | |
1617 | isSafeForScalarRepl(BC, Offset, Info); | |
1618 | } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) { | |
1619 | uint64_t GEPOffset = Offset; | |
1620 | isSafeGEP(GEPI, GEPOffset, Info); | |
1621 | if (!Info.isUnsafe) | |
1622 | isSafeForScalarRepl(GEPI, GEPOffset, Info); | |
1623 | } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) { | |
1624 | ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength()); | |
1a4d82fc | 1625 | if (!Length || Length->isNegative()) |
223e47cc LB |
1626 | return MarkUnsafe(Info, User); |
1627 | ||
1a4d82fc JJ |
1628 | isSafeMemAccess(Offset, Length->getZExtValue(), nullptr, |
1629 | U.getOperandNo() == 0, Info, MI, | |
223e47cc LB |
1630 | true /*AllowWholeAccess*/); |
1631 | } else if (LoadInst *LI = dyn_cast<LoadInst>(User)) { | |
1632 | if (!LI->isSimple()) | |
1633 | return MarkUnsafe(Info, User); | |
1634 | Type *LIType = LI->getType(); | |
1a4d82fc | 1635 | isSafeMemAccess(Offset, DL->getTypeAllocSize(LIType), |
223e47cc LB |
1636 | LIType, false, Info, LI, true /*AllowWholeAccess*/); |
1637 | Info.hasALoadOrStore = true; | |
1638 | ||
1639 | } else if (StoreInst *SI = dyn_cast<StoreInst>(User)) { | |
1640 | // Store is ok if storing INTO the pointer, not storing the pointer | |
1641 | if (!SI->isSimple() || SI->getOperand(0) == I) | |
1642 | return MarkUnsafe(Info, User); | |
1643 | ||
1644 | Type *SIType = SI->getOperand(0)->getType(); | |
1a4d82fc | 1645 | isSafeMemAccess(Offset, DL->getTypeAllocSize(SIType), |
223e47cc LB |
1646 | SIType, true, Info, SI, true /*AllowWholeAccess*/); |
1647 | Info.hasALoadOrStore = true; | |
1648 | } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(User)) { | |
1649 | if (II->getIntrinsicID() != Intrinsic::lifetime_start && | |
1650 | II->getIntrinsicID() != Intrinsic::lifetime_end) | |
1651 | return MarkUnsafe(Info, User); | |
1652 | } else if (isa<PHINode>(User) || isa<SelectInst>(User)) { | |
1653 | isSafePHISelectUseForScalarRepl(User, Offset, Info); | |
1654 | } else { | |
1655 | return MarkUnsafe(Info, User); | |
1656 | } | |
1657 | if (Info.isUnsafe) return; | |
1658 | } | |
1659 | } | |
1660 | ||
1661 | ||
1662 | /// isSafePHIUseForScalarRepl - If we see a PHI node or select using a pointer | |
1663 | /// derived from the alloca, we can often still split the alloca into elements. | |
1664 | /// This is useful if we have a large alloca where one element is phi'd | |
1665 | /// together somewhere: we can SRoA and promote all the other elements even if | |
1666 | /// we end up not being able to promote this one. | |
1667 | /// | |
1668 | /// All we require is that the uses of the PHI do not index into other parts of | |
1669 | /// the alloca. The most important use case for this is single load and stores | |
1670 | /// that are PHI'd together, which can happen due to code sinking. | |
1671 | void SROA::isSafePHISelectUseForScalarRepl(Instruction *I, uint64_t Offset, | |
1672 | AllocaInfo &Info) { | |
1673 | // If we've already checked this PHI, don't do it again. | |
1674 | if (PHINode *PN = dyn_cast<PHINode>(I)) | |
85aaf69f | 1675 | if (!Info.CheckedPHIs.insert(PN).second) |
223e47cc LB |
1676 | return; |
1677 | ||
1a4d82fc JJ |
1678 | for (User *U : I->users()) { |
1679 | Instruction *UI = cast<Instruction>(U); | |
223e47cc | 1680 | |
1a4d82fc | 1681 | if (BitCastInst *BC = dyn_cast<BitCastInst>(UI)) { |
223e47cc | 1682 | isSafePHISelectUseForScalarRepl(BC, Offset, Info); |
1a4d82fc | 1683 | } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(UI)) { |
223e47cc LB |
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()) | |
1a4d82fc | 1688 | return MarkUnsafe(Info, UI); |
223e47cc | 1689 | isSafePHISelectUseForScalarRepl(GEPI, Offset, Info); |
1a4d82fc | 1690 | } else if (LoadInst *LI = dyn_cast<LoadInst>(UI)) { |
223e47cc | 1691 | if (!LI->isSimple()) |
1a4d82fc | 1692 | return MarkUnsafe(Info, UI); |
223e47cc | 1693 | Type *LIType = LI->getType(); |
1a4d82fc | 1694 | isSafeMemAccess(Offset, DL->getTypeAllocSize(LIType), |
223e47cc LB |
1695 | LIType, false, Info, LI, false /*AllowWholeAccess*/); |
1696 | Info.hasALoadOrStore = true; | |
1697 | ||
1a4d82fc | 1698 | } else if (StoreInst *SI = dyn_cast<StoreInst>(UI)) { |
223e47cc LB |
1699 | // Store is ok if storing INTO the pointer, not storing the pointer |
1700 | if (!SI->isSimple() || SI->getOperand(0) == I) | |
1a4d82fc | 1701 | return MarkUnsafe(Info, UI); |
223e47cc LB |
1702 | |
1703 | Type *SIType = SI->getOperand(0)->getType(); | |
1a4d82fc | 1704 | isSafeMemAccess(Offset, DL->getTypeAllocSize(SIType), |
223e47cc LB |
1705 | SIType, true, Info, SI, false /*AllowWholeAccess*/); |
1706 | Info.hasALoadOrStore = true; | |
1a4d82fc JJ |
1707 | } else if (isa<PHINode>(UI) || isa<SelectInst>(UI)) { |
1708 | isSafePHISelectUseForScalarRepl(UI, Offset, Info); | |
223e47cc | 1709 | } else { |
1a4d82fc | 1710 | return MarkUnsafe(Info, UI); |
223e47cc LB |
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()); | |
1a4d82fc JJ |
1737 | if (!IdxVal) |
1738 | return MarkUnsafe(Info, GEPI); | |
223e47cc LB |
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()); | |
1a4d82fc | 1744 | // If this GEP is non-constant then the last operand must have been a |
223e47cc LB |
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(); | |
1a4d82fc | 1749 | Offset += DL->getIndexedOffset(GEPI->getPointerOperandType(), Indices); |
223e47cc LB |
1750 | if (!TypeHasComponent(Info.AI->getAllocatedType(), Offset, |
1751 | NonConstantIdxSize)) | |
1752 | MarkUnsafe(Info, GEPI); | |
1753 | } | |
1754 | ||
1755 | /// isHomogeneousAggregate - Check if type T is a struct or array containing | |
1756 | /// elements of the same type (which is always true for arrays). If so, | |
1757 | /// return true with NumElts and EltTy set to the number of elements and the | |
1758 | /// element type, respectively. | |
1759 | static bool isHomogeneousAggregate(Type *T, unsigned &NumElts, | |
1760 | Type *&EltTy) { | |
1761 | if (ArrayType *AT = dyn_cast<ArrayType>(T)) { | |
1762 | NumElts = AT->getNumElements(); | |
1a4d82fc | 1763 | EltTy = (NumElts == 0 ? nullptr : AT->getElementType()); |
223e47cc LB |
1764 | return true; |
1765 | } | |
1766 | if (StructType *ST = dyn_cast<StructType>(T)) { | |
1767 | NumElts = ST->getNumContainedTypes(); | |
1a4d82fc | 1768 | EltTy = (NumElts == 0 ? nullptr : ST->getContainedType(0)); |
223e47cc LB |
1769 | for (unsigned n = 1; n < NumElts; ++n) { |
1770 | if (ST->getContainedType(n) != EltTy) | |
1771 | return false; | |
1772 | } | |
1773 | return true; | |
1774 | } | |
1775 | return false; | |
1776 | } | |
1777 | ||
1778 | /// isCompatibleAggregate - Check if T1 and T2 are either the same type or are | |
1779 | /// "homogeneous" aggregates with the same element type and number of elements. | |
1780 | static bool isCompatibleAggregate(Type *T1, Type *T2) { | |
1781 | if (T1 == T2) | |
1782 | return true; | |
1783 | ||
1784 | unsigned NumElts1, NumElts2; | |
1785 | Type *EltTy1, *EltTy2; | |
1786 | if (isHomogeneousAggregate(T1, NumElts1, EltTy1) && | |
1787 | isHomogeneousAggregate(T2, NumElts2, EltTy2) && | |
1788 | NumElts1 == NumElts2 && | |
1789 | EltTy1 == EltTy2) | |
1790 | return true; | |
1791 | ||
1792 | return false; | |
1793 | } | |
1794 | ||
1795 | /// isSafeMemAccess - Check if a load/store/memcpy operates on the entire AI | |
1796 | /// alloca or has an offset and size that corresponds to a component element | |
1797 | /// within it. The offset checked here may have been formed from a GEP with a | |
1798 | /// pointer bitcasted to a different type. | |
1799 | /// | |
1800 | /// If AllowWholeAccess is true, then this allows uses of the entire alloca as a | |
1801 | /// unit. If false, it only allows accesses known to be in a single element. | |
1802 | void SROA::isSafeMemAccess(uint64_t Offset, uint64_t MemSize, | |
1803 | Type *MemOpType, bool isStore, | |
1804 | AllocaInfo &Info, Instruction *TheAccess, | |
1805 | bool AllowWholeAccess) { | |
1806 | // Check if this is a load/store of the entire alloca. | |
1807 | if (Offset == 0 && AllowWholeAccess && | |
1a4d82fc | 1808 | MemSize == DL->getTypeAllocSize(Info.AI->getAllocatedType())) { |
223e47cc LB |
1809 | // This can be safe for MemIntrinsics (where MemOpType is 0) and integer |
1810 | // loads/stores (which are essentially the same as the MemIntrinsics with | |
1811 | // regard to copying padding between elements). But, if an alloca is | |
1812 | // flagged as both a source and destination of such operations, we'll need | |
1813 | // to check later for padding between elements. | |
1814 | if (!MemOpType || MemOpType->isIntegerTy()) { | |
1815 | if (isStore) | |
1816 | Info.isMemCpyDst = true; | |
1817 | else | |
1818 | Info.isMemCpySrc = true; | |
1819 | return; | |
1820 | } | |
1821 | // This is also safe for references using a type that is compatible with | |
1822 | // the type of the alloca, so that loads/stores can be rewritten using | |
1823 | // insertvalue/extractvalue. | |
1824 | if (isCompatibleAggregate(MemOpType, Info.AI->getAllocatedType())) { | |
1825 | Info.hasSubelementAccess = true; | |
1826 | return; | |
1827 | } | |
1828 | } | |
1829 | // Check if the offset/size correspond to a component within the alloca type. | |
1830 | Type *T = Info.AI->getAllocatedType(); | |
1831 | if (TypeHasComponent(T, Offset, MemSize)) { | |
1832 | Info.hasSubelementAccess = true; | |
1833 | return; | |
1834 | } | |
1835 | ||
1836 | return MarkUnsafe(Info, TheAccess); | |
1837 | } | |
1838 | ||
1839 | /// TypeHasComponent - Return true if T has a component type with the | |
1840 | /// specified offset and size. If Size is zero, do not check the size. | |
1841 | bool SROA::TypeHasComponent(Type *T, uint64_t Offset, uint64_t Size) { | |
1842 | Type *EltTy; | |
1843 | uint64_t EltSize; | |
1844 | if (StructType *ST = dyn_cast<StructType>(T)) { | |
1a4d82fc | 1845 | const StructLayout *Layout = DL->getStructLayout(ST); |
223e47cc LB |
1846 | unsigned EltIdx = Layout->getElementContainingOffset(Offset); |
1847 | EltTy = ST->getContainedType(EltIdx); | |
1a4d82fc | 1848 | EltSize = DL->getTypeAllocSize(EltTy); |
223e47cc LB |
1849 | Offset -= Layout->getElementOffset(EltIdx); |
1850 | } else if (ArrayType *AT = dyn_cast<ArrayType>(T)) { | |
1851 | EltTy = AT->getElementType(); | |
1a4d82fc | 1852 | EltSize = DL->getTypeAllocSize(EltTy); |
223e47cc LB |
1853 | if (Offset >= AT->getNumElements() * EltSize) |
1854 | return false; | |
1855 | Offset %= EltSize; | |
1856 | } else if (VectorType *VT = dyn_cast<VectorType>(T)) { | |
1857 | EltTy = VT->getElementType(); | |
1a4d82fc | 1858 | EltSize = DL->getTypeAllocSize(EltTy); |
223e47cc LB |
1859 | if (Offset >= VT->getNumElements() * EltSize) |
1860 | return false; | |
1861 | Offset %= EltSize; | |
1862 | } else { | |
1863 | return false; | |
1864 | } | |
1865 | if (Offset == 0 && (Size == 0 || EltSize == Size)) | |
1866 | return true; | |
1867 | // Check if the component spans multiple elements. | |
1868 | if (Offset + Size > EltSize) | |
1869 | return false; | |
1870 | return TypeHasComponent(EltTy, Offset, Size); | |
1871 | } | |
1872 | ||
1873 | /// RewriteForScalarRepl - Alloca AI is being split into NewElts, so rewrite | |
1874 | /// the instruction I, which references it, to use the separate elements. | |
1875 | /// Offset indicates the position within AI that is referenced by this | |
1876 | /// instruction. | |
1877 | void SROA::RewriteForScalarRepl(Instruction *I, AllocaInst *AI, uint64_t Offset, | |
1a4d82fc | 1878 | SmallVectorImpl<AllocaInst *> &NewElts) { |
223e47cc | 1879 | for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI!=E;) { |
1a4d82fc JJ |
1880 | Use &TheUse = *UI++; |
1881 | Instruction *User = cast<Instruction>(TheUse.getUser()); | |
223e47cc LB |
1882 | |
1883 | if (BitCastInst *BC = dyn_cast<BitCastInst>(User)) { | |
1884 | RewriteBitCast(BC, AI, Offset, NewElts); | |
1885 | continue; | |
1886 | } | |
1887 | ||
1888 | if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(User)) { | |
1889 | RewriteGEP(GEPI, AI, Offset, NewElts); | |
1890 | continue; | |
1891 | } | |
1892 | ||
1893 | if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(User)) { | |
1894 | ConstantInt *Length = dyn_cast<ConstantInt>(MI->getLength()); | |
1895 | uint64_t MemSize = Length->getZExtValue(); | |
1896 | if (Offset == 0 && | |
1a4d82fc | 1897 | MemSize == DL->getTypeAllocSize(AI->getAllocatedType())) |
223e47cc LB |
1898 | RewriteMemIntrinUserOfAlloca(MI, I, AI, NewElts); |
1899 | // Otherwise the intrinsic can only touch a single element and the | |
1900 | // address operand will be updated, so nothing else needs to be done. | |
1901 | continue; | |
1902 | } | |
1903 | ||
1904 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(User)) { | |
1905 | if (II->getIntrinsicID() == Intrinsic::lifetime_start || | |
1906 | II->getIntrinsicID() == Intrinsic::lifetime_end) { | |
1907 | RewriteLifetimeIntrinsic(II, AI, Offset, NewElts); | |
1908 | } | |
1909 | continue; | |
1910 | } | |
1911 | ||
1912 | if (LoadInst *LI = dyn_cast<LoadInst>(User)) { | |
1913 | Type *LIType = LI->getType(); | |
1914 | ||
1915 | if (isCompatibleAggregate(LIType, AI->getAllocatedType())) { | |
1916 | // Replace: | |
1917 | // %res = load { i32, i32 }* %alloc | |
1918 | // with: | |
1919 | // %load.0 = load i32* %alloc.0 | |
1920 | // %insert.0 insertvalue { i32, i32 } zeroinitializer, i32 %load.0, 0 | |
1921 | // %load.1 = load i32* %alloc.1 | |
1922 | // %insert = insertvalue { i32, i32 } %insert.0, i32 %load.1, 1 | |
1923 | // (Also works for arrays instead of structs) | |
1924 | Value *Insert = UndefValue::get(LIType); | |
1925 | IRBuilder<> Builder(LI); | |
1926 | for (unsigned i = 0, e = NewElts.size(); i != e; ++i) { | |
1927 | Value *Load = Builder.CreateLoad(NewElts[i], "load"); | |
1928 | Insert = Builder.CreateInsertValue(Insert, Load, i, "insert"); | |
1929 | } | |
1930 | LI->replaceAllUsesWith(Insert); | |
1931 | DeadInsts.push_back(LI); | |
1932 | } else if (LIType->isIntegerTy() && | |
1a4d82fc JJ |
1933 | DL->getTypeAllocSize(LIType) == |
1934 | DL->getTypeAllocSize(AI->getAllocatedType())) { | |
223e47cc LB |
1935 | // If this is a load of the entire alloca to an integer, rewrite it. |
1936 | RewriteLoadUserOfWholeAlloca(LI, AI, NewElts); | |
1937 | } | |
1938 | continue; | |
1939 | } | |
1940 | ||
1941 | if (StoreInst *SI = dyn_cast<StoreInst>(User)) { | |
1942 | Value *Val = SI->getOperand(0); | |
1943 | Type *SIType = Val->getType(); | |
1944 | if (isCompatibleAggregate(SIType, AI->getAllocatedType())) { | |
1945 | // Replace: | |
1946 | // store { i32, i32 } %val, { i32, i32 }* %alloc | |
1947 | // with: | |
1948 | // %val.0 = extractvalue { i32, i32 } %val, 0 | |
1949 | // store i32 %val.0, i32* %alloc.0 | |
1950 | // %val.1 = extractvalue { i32, i32 } %val, 1 | |
1951 | // store i32 %val.1, i32* %alloc.1 | |
1952 | // (Also works for arrays instead of structs) | |
1953 | IRBuilder<> Builder(SI); | |
1954 | for (unsigned i = 0, e = NewElts.size(); i != e; ++i) { | |
1955 | Value *Extract = Builder.CreateExtractValue(Val, i, Val->getName()); | |
1956 | Builder.CreateStore(Extract, NewElts[i]); | |
1957 | } | |
1958 | DeadInsts.push_back(SI); | |
1959 | } else if (SIType->isIntegerTy() && | |
1a4d82fc JJ |
1960 | DL->getTypeAllocSize(SIType) == |
1961 | DL->getTypeAllocSize(AI->getAllocatedType())) { | |
223e47cc LB |
1962 | // If this is a store of the entire alloca from an integer, rewrite it. |
1963 | RewriteStoreUserOfWholeAlloca(SI, AI, NewElts); | |
1964 | } | |
1965 | continue; | |
1966 | } | |
1967 | ||
1968 | if (isa<SelectInst>(User) || isa<PHINode>(User)) { | |
1969 | // If we have a PHI user of the alloca itself (as opposed to a GEP or | |
1970 | // bitcast) we have to rewrite it. GEP and bitcast uses will be RAUW'd to | |
1971 | // the new pointer. | |
1972 | if (!isa<AllocaInst>(I)) continue; | |
1973 | ||
1974 | assert(Offset == 0 && NewElts[0] && | |
1975 | "Direct alloca use should have a zero offset"); | |
1976 | ||
1977 | // If we have a use of the alloca, we know the derived uses will be | |
1978 | // utilizing just the first element of the scalarized result. Insert a | |
1979 | // bitcast of the first alloca before the user as required. | |
1980 | AllocaInst *NewAI = NewElts[0]; | |
1981 | BitCastInst *BCI = new BitCastInst(NewAI, AI->getType(), "", NewAI); | |
1982 | NewAI->moveBefore(BCI); | |
1983 | TheUse = BCI; | |
1984 | continue; | |
1985 | } | |
1986 | } | |
1987 | } | |
1988 | ||
1989 | /// RewriteBitCast - Update a bitcast reference to the alloca being replaced | |
1990 | /// and recursively continue updating all of its uses. | |
1991 | void SROA::RewriteBitCast(BitCastInst *BC, AllocaInst *AI, uint64_t Offset, | |
1a4d82fc | 1992 | SmallVectorImpl<AllocaInst *> &NewElts) { |
223e47cc LB |
1993 | RewriteForScalarRepl(BC, AI, Offset, NewElts); |
1994 | if (BC->getOperand(0) != AI) | |
1995 | return; | |
1996 | ||
1997 | // The bitcast references the original alloca. Replace its uses with | |
1998 | // references to the alloca containing offset zero (which is normally at | |
1999 | // index zero, but might not be in cases involving structs with elements | |
2000 | // of size zero). | |
2001 | Type *T = AI->getAllocatedType(); | |
2002 | uint64_t EltOffset = 0; | |
2003 | Type *IdxTy; | |
2004 | uint64_t Idx = FindElementAndOffset(T, EltOffset, IdxTy); | |
2005 | Instruction *Val = NewElts[Idx]; | |
2006 | if (Val->getType() != BC->getDestTy()) { | |
2007 | Val = new BitCastInst(Val, BC->getDestTy(), "", BC); | |
2008 | Val->takeName(BC); | |
2009 | } | |
2010 | BC->replaceAllUsesWith(Val); | |
2011 | DeadInsts.push_back(BC); | |
2012 | } | |
2013 | ||
2014 | /// FindElementAndOffset - Return the index of the element containing Offset | |
2015 | /// within the specified type, which must be either a struct or an array. | |
2016 | /// Sets T to the type of the element and Offset to the offset within that | |
2017 | /// element. IdxTy is set to the type of the index result to be used in a | |
2018 | /// GEP instruction. | |
2019 | uint64_t SROA::FindElementAndOffset(Type *&T, uint64_t &Offset, | |
2020 | Type *&IdxTy) { | |
2021 | uint64_t Idx = 0; | |
2022 | if (StructType *ST = dyn_cast<StructType>(T)) { | |
1a4d82fc | 2023 | const StructLayout *Layout = DL->getStructLayout(ST); |
223e47cc LB |
2024 | Idx = Layout->getElementContainingOffset(Offset); |
2025 | T = ST->getContainedType(Idx); | |
2026 | Offset -= Layout->getElementOffset(Idx); | |
2027 | IdxTy = Type::getInt32Ty(T->getContext()); | |
2028 | return Idx; | |
2029 | } else if (ArrayType *AT = dyn_cast<ArrayType>(T)) { | |
2030 | T = AT->getElementType(); | |
1a4d82fc | 2031 | uint64_t EltSize = DL->getTypeAllocSize(T); |
223e47cc LB |
2032 | Idx = Offset / EltSize; |
2033 | Offset -= Idx * EltSize; | |
2034 | IdxTy = Type::getInt64Ty(T->getContext()); | |
2035 | return Idx; | |
2036 | } | |
2037 | VectorType *VT = cast<VectorType>(T); | |
2038 | T = VT->getElementType(); | |
1a4d82fc | 2039 | uint64_t EltSize = DL->getTypeAllocSize(T); |
223e47cc LB |
2040 | Idx = Offset / EltSize; |
2041 | Offset -= Idx * EltSize; | |
2042 | IdxTy = Type::getInt64Ty(T->getContext()); | |
2043 | return Idx; | |
2044 | } | |
2045 | ||
2046 | /// RewriteGEP - Check if this GEP instruction moves the pointer across | |
2047 | /// elements of the alloca that are being split apart, and if so, rewrite | |
2048 | /// the GEP to be relative to the new element. | |
2049 | void SROA::RewriteGEP(GetElementPtrInst *GEPI, AllocaInst *AI, uint64_t Offset, | |
1a4d82fc | 2050 | SmallVectorImpl<AllocaInst *> &NewElts) { |
223e47cc LB |
2051 | uint64_t OldOffset = Offset; |
2052 | SmallVector<Value*, 8> Indices(GEPI->op_begin() + 1, GEPI->op_end()); | |
2053 | // If the GEP was dynamic then it must have been a dynamic vector lookup. | |
2054 | // In this case, it must be the last GEP operand which is dynamic so keep that | |
2055 | // aside until we've found the constant GEP offset then add it back in at the | |
2056 | // end. | |
1a4d82fc | 2057 | Value* NonConstantIdx = nullptr; |
223e47cc LB |
2058 | if (!GEPI->hasAllConstantIndices()) |
2059 | NonConstantIdx = Indices.pop_back_val(); | |
1a4d82fc | 2060 | Offset += DL->getIndexedOffset(GEPI->getPointerOperandType(), Indices); |
223e47cc LB |
2061 | |
2062 | RewriteForScalarRepl(GEPI, AI, Offset, NewElts); | |
2063 | ||
2064 | Type *T = AI->getAllocatedType(); | |
2065 | Type *IdxTy; | |
2066 | uint64_t OldIdx = FindElementAndOffset(T, OldOffset, IdxTy); | |
2067 | if (GEPI->getOperand(0) == AI) | |
2068 | OldIdx = ~0ULL; // Force the GEP to be rewritten. | |
2069 | ||
2070 | T = AI->getAllocatedType(); | |
2071 | uint64_t EltOffset = Offset; | |
2072 | uint64_t Idx = FindElementAndOffset(T, EltOffset, IdxTy); | |
2073 | ||
2074 | // If this GEP does not move the pointer across elements of the alloca | |
2075 | // being split, then it does not needs to be rewritten. | |
2076 | if (Idx == OldIdx) | |
2077 | return; | |
2078 | ||
2079 | Type *i32Ty = Type::getInt32Ty(AI->getContext()); | |
2080 | SmallVector<Value*, 8> NewArgs; | |
2081 | NewArgs.push_back(Constant::getNullValue(i32Ty)); | |
2082 | while (EltOffset != 0) { | |
2083 | uint64_t EltIdx = FindElementAndOffset(T, EltOffset, IdxTy); | |
2084 | NewArgs.push_back(ConstantInt::get(IdxTy, EltIdx)); | |
2085 | } | |
2086 | if (NonConstantIdx) { | |
2087 | Type* GepTy = T; | |
2088 | // This GEP has a dynamic index. We need to add "i32 0" to index through | |
2089 | // any structs or arrays in the original type until we get to the vector | |
2090 | // to index. | |
2091 | while (!isa<VectorType>(GepTy)) { | |
2092 | NewArgs.push_back(Constant::getNullValue(i32Ty)); | |
2093 | GepTy = cast<CompositeType>(GepTy)->getTypeAtIndex(0U); | |
2094 | } | |
2095 | NewArgs.push_back(NonConstantIdx); | |
2096 | } | |
2097 | Instruction *Val = NewElts[Idx]; | |
2098 | if (NewArgs.size() > 1) { | |
2099 | Val = GetElementPtrInst::CreateInBounds(Val, NewArgs, "", GEPI); | |
2100 | Val->takeName(GEPI); | |
2101 | } | |
2102 | if (Val->getType() != GEPI->getType()) | |
2103 | Val = new BitCastInst(Val, GEPI->getType(), Val->getName(), GEPI); | |
2104 | GEPI->replaceAllUsesWith(Val); | |
2105 | DeadInsts.push_back(GEPI); | |
2106 | } | |
2107 | ||
2108 | /// RewriteLifetimeIntrinsic - II is a lifetime.start/lifetime.end. Rewrite it | |
2109 | /// to mark the lifetime of the scalarized memory. | |
2110 | void SROA::RewriteLifetimeIntrinsic(IntrinsicInst *II, AllocaInst *AI, | |
2111 | uint64_t Offset, | |
1a4d82fc | 2112 | SmallVectorImpl<AllocaInst *> &NewElts) { |
223e47cc LB |
2113 | ConstantInt *OldSize = cast<ConstantInt>(II->getArgOperand(0)); |
2114 | // Put matching lifetime markers on everything from Offset up to | |
2115 | // Offset+OldSize. | |
2116 | Type *AIType = AI->getAllocatedType(); | |
2117 | uint64_t NewOffset = Offset; | |
2118 | Type *IdxTy; | |
2119 | uint64_t Idx = FindElementAndOffset(AIType, NewOffset, IdxTy); | |
2120 | ||
2121 | IRBuilder<> Builder(II); | |
2122 | uint64_t Size = OldSize->getLimitedValue(); | |
2123 | ||
2124 | if (NewOffset) { | |
2125 | // Splice the first element and index 'NewOffset' bytes in. SROA will | |
2126 | // split the alloca again later. | |
1a4d82fc JJ |
2127 | unsigned AS = AI->getType()->getAddressSpace(); |
2128 | Value *V = Builder.CreateBitCast(NewElts[Idx], Builder.getInt8PtrTy(AS)); | |
223e47cc LB |
2129 | V = Builder.CreateGEP(V, Builder.getInt64(NewOffset)); |
2130 | ||
2131 | IdxTy = NewElts[Idx]->getAllocatedType(); | |
1a4d82fc | 2132 | uint64_t EltSize = DL->getTypeAllocSize(IdxTy) - NewOffset; |
223e47cc LB |
2133 | if (EltSize > Size) { |
2134 | EltSize = Size; | |
2135 | Size = 0; | |
2136 | } else { | |
2137 | Size -= EltSize; | |
2138 | } | |
2139 | if (II->getIntrinsicID() == Intrinsic::lifetime_start) | |
2140 | Builder.CreateLifetimeStart(V, Builder.getInt64(EltSize)); | |
2141 | else | |
2142 | Builder.CreateLifetimeEnd(V, Builder.getInt64(EltSize)); | |
2143 | ++Idx; | |
2144 | } | |
2145 | ||
2146 | for (; Idx != NewElts.size() && Size; ++Idx) { | |
2147 | IdxTy = NewElts[Idx]->getAllocatedType(); | |
1a4d82fc | 2148 | uint64_t EltSize = DL->getTypeAllocSize(IdxTy); |
223e47cc LB |
2149 | if (EltSize > Size) { |
2150 | EltSize = Size; | |
2151 | Size = 0; | |
2152 | } else { | |
2153 | Size -= EltSize; | |
2154 | } | |
2155 | if (II->getIntrinsicID() == Intrinsic::lifetime_start) | |
2156 | Builder.CreateLifetimeStart(NewElts[Idx], | |
2157 | Builder.getInt64(EltSize)); | |
2158 | else | |
2159 | Builder.CreateLifetimeEnd(NewElts[Idx], | |
2160 | Builder.getInt64(EltSize)); | |
2161 | } | |
2162 | DeadInsts.push_back(II); | |
2163 | } | |
2164 | ||
2165 | /// RewriteMemIntrinUserOfAlloca - MI is a memcpy/memset/memmove from or to AI. | |
2166 | /// Rewrite it to copy or set the elements of the scalarized memory. | |
1a4d82fc JJ |
2167 | void |
2168 | SROA::RewriteMemIntrinUserOfAlloca(MemIntrinsic *MI, Instruction *Inst, | |
2169 | AllocaInst *AI, | |
2170 | SmallVectorImpl<AllocaInst *> &NewElts) { | |
223e47cc LB |
2171 | // If this is a memcpy/memmove, construct the other pointer as the |
2172 | // appropriate type. The "Other" pointer is the pointer that goes to memory | |
2173 | // that doesn't have anything to do with the alloca that we are promoting. For | |
2174 | // memset, this Value* stays null. | |
1a4d82fc | 2175 | Value *OtherPtr = nullptr; |
223e47cc LB |
2176 | unsigned MemAlignment = MI->getAlignment(); |
2177 | if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) { // memmove/memcopy | |
2178 | if (Inst == MTI->getRawDest()) | |
2179 | OtherPtr = MTI->getRawSource(); | |
2180 | else { | |
2181 | assert(Inst == MTI->getRawSource()); | |
2182 | OtherPtr = MTI->getRawDest(); | |
2183 | } | |
2184 | } | |
2185 | ||
2186 | // If there is an other pointer, we want to convert it to the same pointer | |
2187 | // type as AI has, so we can GEP through it safely. | |
2188 | if (OtherPtr) { | |
2189 | unsigned AddrSpace = | |
2190 | cast<PointerType>(OtherPtr->getType())->getAddressSpace(); | |
2191 | ||
2192 | // Remove bitcasts and all-zero GEPs from OtherPtr. This is an | |
2193 | // optimization, but it's also required to detect the corner case where | |
2194 | // both pointer operands are referencing the same memory, and where | |
2195 | // OtherPtr may be a bitcast or GEP that currently being rewritten. (This | |
2196 | // function is only called for mem intrinsics that access the whole | |
2197 | // aggregate, so non-zero GEPs are not an issue here.) | |
2198 | OtherPtr = OtherPtr->stripPointerCasts(); | |
2199 | ||
2200 | // Copying the alloca to itself is a no-op: just delete it. | |
2201 | if (OtherPtr == AI || OtherPtr == NewElts[0]) { | |
2202 | // This code will run twice for a no-op memcpy -- once for each operand. | |
2203 | // Put only one reference to MI on the DeadInsts list. | |
1a4d82fc | 2204 | for (SmallVectorImpl<Value *>::const_iterator I = DeadInsts.begin(), |
223e47cc LB |
2205 | E = DeadInsts.end(); I != E; ++I) |
2206 | if (*I == MI) return; | |
2207 | DeadInsts.push_back(MI); | |
2208 | return; | |
2209 | } | |
2210 | ||
2211 | // If the pointer is not the right type, insert a bitcast to the right | |
2212 | // type. | |
2213 | Type *NewTy = | |
2214 | PointerType::get(AI->getType()->getElementType(), AddrSpace); | |
2215 | ||
2216 | if (OtherPtr->getType() != NewTy) | |
2217 | OtherPtr = new BitCastInst(OtherPtr, NewTy, OtherPtr->getName(), MI); | |
2218 | } | |
2219 | ||
2220 | // Process each element of the aggregate. | |
2221 | bool SROADest = MI->getRawDest() == Inst; | |
2222 | ||
2223 | Constant *Zero = Constant::getNullValue(Type::getInt32Ty(MI->getContext())); | |
2224 | ||
2225 | for (unsigned i = 0, e = NewElts.size(); i != e; ++i) { | |
2226 | // If this is a memcpy/memmove, emit a GEP of the other element address. | |
1a4d82fc | 2227 | Value *OtherElt = nullptr; |
223e47cc LB |
2228 | unsigned OtherEltAlign = MemAlignment; |
2229 | ||
2230 | if (OtherPtr) { | |
2231 | Value *Idx[2] = { Zero, | |
2232 | ConstantInt::get(Type::getInt32Ty(MI->getContext()), i) }; | |
2233 | OtherElt = GetElementPtrInst::CreateInBounds(OtherPtr, Idx, | |
2234 | OtherPtr->getName()+"."+Twine(i), | |
2235 | MI); | |
2236 | uint64_t EltOffset; | |
2237 | PointerType *OtherPtrTy = cast<PointerType>(OtherPtr->getType()); | |
2238 | Type *OtherTy = OtherPtrTy->getElementType(); | |
2239 | if (StructType *ST = dyn_cast<StructType>(OtherTy)) { | |
1a4d82fc | 2240 | EltOffset = DL->getStructLayout(ST)->getElementOffset(i); |
223e47cc LB |
2241 | } else { |
2242 | Type *EltTy = cast<SequentialType>(OtherTy)->getElementType(); | |
1a4d82fc | 2243 | EltOffset = DL->getTypeAllocSize(EltTy)*i; |
223e47cc LB |
2244 | } |
2245 | ||
2246 | // The alignment of the other pointer is the guaranteed alignment of the | |
2247 | // element, which is affected by both the known alignment of the whole | |
2248 | // mem intrinsic and the alignment of the element. If the alignment of | |
2249 | // the memcpy (f.e.) is 32 but the element is at a 4-byte offset, then the | |
2250 | // known alignment is just 4 bytes. | |
2251 | OtherEltAlign = (unsigned)MinAlign(OtherEltAlign, EltOffset); | |
2252 | } | |
2253 | ||
2254 | Value *EltPtr = NewElts[i]; | |
2255 | Type *EltTy = cast<PointerType>(EltPtr->getType())->getElementType(); | |
2256 | ||
2257 | // If we got down to a scalar, insert a load or store as appropriate. | |
2258 | if (EltTy->isSingleValueType()) { | |
2259 | if (isa<MemTransferInst>(MI)) { | |
2260 | if (SROADest) { | |
2261 | // From Other to Alloca. | |
2262 | Value *Elt = new LoadInst(OtherElt, "tmp", false, OtherEltAlign, MI); | |
2263 | new StoreInst(Elt, EltPtr, MI); | |
2264 | } else { | |
2265 | // From Alloca to Other. | |
2266 | Value *Elt = new LoadInst(EltPtr, "tmp", MI); | |
2267 | new StoreInst(Elt, OtherElt, false, OtherEltAlign, MI); | |
2268 | } | |
2269 | continue; | |
2270 | } | |
2271 | assert(isa<MemSetInst>(MI)); | |
2272 | ||
2273 | // If the stored element is zero (common case), just store a null | |
2274 | // constant. | |
2275 | Constant *StoreVal; | |
2276 | if (ConstantInt *CI = dyn_cast<ConstantInt>(MI->getArgOperand(1))) { | |
2277 | if (CI->isZero()) { | |
2278 | StoreVal = Constant::getNullValue(EltTy); // 0.0, null, 0, <0,0> | |
2279 | } else { | |
2280 | // If EltTy is a vector type, get the element type. | |
2281 | Type *ValTy = EltTy->getScalarType(); | |
2282 | ||
2283 | // Construct an integer with the right value. | |
1a4d82fc | 2284 | unsigned EltSize = DL->getTypeSizeInBits(ValTy); |
223e47cc LB |
2285 | APInt OneVal(EltSize, CI->getZExtValue()); |
2286 | APInt TotalVal(OneVal); | |
2287 | // Set each byte. | |
2288 | for (unsigned i = 0; 8*i < EltSize; ++i) { | |
2289 | TotalVal = TotalVal.shl(8); | |
2290 | TotalVal |= OneVal; | |
2291 | } | |
2292 | ||
2293 | // Convert the integer value to the appropriate type. | |
2294 | StoreVal = ConstantInt::get(CI->getContext(), TotalVal); | |
2295 | if (ValTy->isPointerTy()) | |
2296 | StoreVal = ConstantExpr::getIntToPtr(StoreVal, ValTy); | |
2297 | else if (ValTy->isFloatingPointTy()) | |
2298 | StoreVal = ConstantExpr::getBitCast(StoreVal, ValTy); | |
2299 | assert(StoreVal->getType() == ValTy && "Type mismatch!"); | |
2300 | ||
2301 | // If the requested value was a vector constant, create it. | |
2302 | if (EltTy->isVectorTy()) { | |
2303 | unsigned NumElts = cast<VectorType>(EltTy)->getNumElements(); | |
2304 | StoreVal = ConstantVector::getSplat(NumElts, StoreVal); | |
2305 | } | |
2306 | } | |
2307 | new StoreInst(StoreVal, EltPtr, MI); | |
2308 | continue; | |
2309 | } | |
2310 | // Otherwise, if we're storing a byte variable, use a memset call for | |
2311 | // this element. | |
2312 | } | |
2313 | ||
1a4d82fc | 2314 | unsigned EltSize = DL->getTypeAllocSize(EltTy); |
223e47cc LB |
2315 | if (!EltSize) |
2316 | continue; | |
2317 | ||
2318 | IRBuilder<> Builder(MI); | |
2319 | ||
2320 | // Finally, insert the meminst for this element. | |
2321 | if (isa<MemSetInst>(MI)) { | |
2322 | Builder.CreateMemSet(EltPtr, MI->getArgOperand(1), EltSize, | |
2323 | MI->isVolatile()); | |
2324 | } else { | |
2325 | assert(isa<MemTransferInst>(MI)); | |
2326 | Value *Dst = SROADest ? EltPtr : OtherElt; // Dest ptr | |
2327 | Value *Src = SROADest ? OtherElt : EltPtr; // Src ptr | |
2328 | ||
2329 | if (isa<MemCpyInst>(MI)) | |
2330 | Builder.CreateMemCpy(Dst, Src, EltSize, OtherEltAlign,MI->isVolatile()); | |
2331 | else | |
2332 | Builder.CreateMemMove(Dst, Src, EltSize,OtherEltAlign,MI->isVolatile()); | |
2333 | } | |
2334 | } | |
2335 | DeadInsts.push_back(MI); | |
2336 | } | |
2337 | ||
2338 | /// RewriteStoreUserOfWholeAlloca - We found a store of an integer that | |
2339 | /// overwrites the entire allocation. Extract out the pieces of the stored | |
2340 | /// integer and store them individually. | |
1a4d82fc JJ |
2341 | void |
2342 | SROA::RewriteStoreUserOfWholeAlloca(StoreInst *SI, AllocaInst *AI, | |
2343 | SmallVectorImpl<AllocaInst *> &NewElts) { | |
223e47cc LB |
2344 | // Extract each element out of the integer according to its structure offset |
2345 | // and store the element value to the individual alloca. | |
2346 | Value *SrcVal = SI->getOperand(0); | |
2347 | Type *AllocaEltTy = AI->getAllocatedType(); | |
1a4d82fc | 2348 | uint64_t AllocaSizeBits = DL->getTypeAllocSizeInBits(AllocaEltTy); |
223e47cc LB |
2349 | |
2350 | IRBuilder<> Builder(SI); | |
2351 | ||
2352 | // Handle tail padding by extending the operand | |
1a4d82fc | 2353 | if (DL->getTypeSizeInBits(SrcVal->getType()) != AllocaSizeBits) |
223e47cc LB |
2354 | SrcVal = Builder.CreateZExt(SrcVal, |
2355 | IntegerType::get(SI->getContext(), AllocaSizeBits)); | |
2356 | ||
2357 | DEBUG(dbgs() << "PROMOTING STORE TO WHOLE ALLOCA: " << *AI << '\n' << *SI | |
2358 | << '\n'); | |
2359 | ||
2360 | // There are two forms here: AI could be an array or struct. Both cases | |
2361 | // have different ways to compute the element offset. | |
2362 | if (StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) { | |
1a4d82fc | 2363 | const StructLayout *Layout = DL->getStructLayout(EltSTy); |
223e47cc LB |
2364 | |
2365 | for (unsigned i = 0, e = NewElts.size(); i != e; ++i) { | |
2366 | // Get the number of bits to shift SrcVal to get the value. | |
2367 | Type *FieldTy = EltSTy->getElementType(i); | |
2368 | uint64_t Shift = Layout->getElementOffsetInBits(i); | |
2369 | ||
1a4d82fc JJ |
2370 | if (DL->isBigEndian()) |
2371 | Shift = AllocaSizeBits-Shift-DL->getTypeAllocSizeInBits(FieldTy); | |
223e47cc LB |
2372 | |
2373 | Value *EltVal = SrcVal; | |
2374 | if (Shift) { | |
2375 | Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift); | |
2376 | EltVal = Builder.CreateLShr(EltVal, ShiftVal, "sroa.store.elt"); | |
2377 | } | |
2378 | ||
2379 | // Truncate down to an integer of the right size. | |
1a4d82fc | 2380 | uint64_t FieldSizeBits = DL->getTypeSizeInBits(FieldTy); |
223e47cc LB |
2381 | |
2382 | // Ignore zero sized fields like {}, they obviously contain no data. | |
2383 | if (FieldSizeBits == 0) continue; | |
2384 | ||
2385 | if (FieldSizeBits != AllocaSizeBits) | |
2386 | EltVal = Builder.CreateTrunc(EltVal, | |
2387 | IntegerType::get(SI->getContext(), FieldSizeBits)); | |
2388 | Value *DestField = NewElts[i]; | |
2389 | if (EltVal->getType() == FieldTy) { | |
2390 | // Storing to an integer field of this size, just do it. | |
2391 | } else if (FieldTy->isFloatingPointTy() || FieldTy->isVectorTy()) { | |
2392 | // Bitcast to the right element type (for fp/vector values). | |
2393 | EltVal = Builder.CreateBitCast(EltVal, FieldTy); | |
2394 | } else { | |
2395 | // Otherwise, bitcast the dest pointer (for aggregates). | |
2396 | DestField = Builder.CreateBitCast(DestField, | |
2397 | PointerType::getUnqual(EltVal->getType())); | |
2398 | } | |
2399 | new StoreInst(EltVal, DestField, SI); | |
2400 | } | |
2401 | ||
2402 | } else { | |
2403 | ArrayType *ATy = cast<ArrayType>(AllocaEltTy); | |
2404 | Type *ArrayEltTy = ATy->getElementType(); | |
1a4d82fc JJ |
2405 | uint64_t ElementOffset = DL->getTypeAllocSizeInBits(ArrayEltTy); |
2406 | uint64_t ElementSizeBits = DL->getTypeSizeInBits(ArrayEltTy); | |
223e47cc LB |
2407 | |
2408 | uint64_t Shift; | |
2409 | ||
1a4d82fc | 2410 | if (DL->isBigEndian()) |
223e47cc LB |
2411 | Shift = AllocaSizeBits-ElementOffset; |
2412 | else | |
2413 | Shift = 0; | |
2414 | ||
2415 | for (unsigned i = 0, e = NewElts.size(); i != e; ++i) { | |
2416 | // Ignore zero sized fields like {}, they obviously contain no data. | |
2417 | if (ElementSizeBits == 0) continue; | |
2418 | ||
2419 | Value *EltVal = SrcVal; | |
2420 | if (Shift) { | |
2421 | Value *ShiftVal = ConstantInt::get(EltVal->getType(), Shift); | |
2422 | EltVal = Builder.CreateLShr(EltVal, ShiftVal, "sroa.store.elt"); | |
2423 | } | |
2424 | ||
2425 | // Truncate down to an integer of the right size. | |
2426 | if (ElementSizeBits != AllocaSizeBits) | |
2427 | EltVal = Builder.CreateTrunc(EltVal, | |
2428 | IntegerType::get(SI->getContext(), | |
2429 | ElementSizeBits)); | |
2430 | Value *DestField = NewElts[i]; | |
2431 | if (EltVal->getType() == ArrayEltTy) { | |
2432 | // Storing to an integer field of this size, just do it. | |
2433 | } else if (ArrayEltTy->isFloatingPointTy() || | |
2434 | ArrayEltTy->isVectorTy()) { | |
2435 | // Bitcast to the right element type (for fp/vector values). | |
2436 | EltVal = Builder.CreateBitCast(EltVal, ArrayEltTy); | |
2437 | } else { | |
2438 | // Otherwise, bitcast the dest pointer (for aggregates). | |
2439 | DestField = Builder.CreateBitCast(DestField, | |
2440 | PointerType::getUnqual(EltVal->getType())); | |
2441 | } | |
2442 | new StoreInst(EltVal, DestField, SI); | |
2443 | ||
1a4d82fc | 2444 | if (DL->isBigEndian()) |
223e47cc LB |
2445 | Shift -= ElementOffset; |
2446 | else | |
2447 | Shift += ElementOffset; | |
2448 | } | |
2449 | } | |
2450 | ||
2451 | DeadInsts.push_back(SI); | |
2452 | } | |
2453 | ||
2454 | /// RewriteLoadUserOfWholeAlloca - We found a load of the entire allocation to | |
2455 | /// an integer. Load the individual pieces to form the aggregate value. | |
1a4d82fc JJ |
2456 | void |
2457 | SROA::RewriteLoadUserOfWholeAlloca(LoadInst *LI, AllocaInst *AI, | |
2458 | SmallVectorImpl<AllocaInst *> &NewElts) { | |
223e47cc LB |
2459 | // Extract each element out of the NewElts according to its structure offset |
2460 | // and form the result value. | |
2461 | Type *AllocaEltTy = AI->getAllocatedType(); | |
1a4d82fc | 2462 | uint64_t AllocaSizeBits = DL->getTypeAllocSizeInBits(AllocaEltTy); |
223e47cc LB |
2463 | |
2464 | DEBUG(dbgs() << "PROMOTING LOAD OF WHOLE ALLOCA: " << *AI << '\n' << *LI | |
2465 | << '\n'); | |
2466 | ||
2467 | // There are two forms here: AI could be an array or struct. Both cases | |
2468 | // have different ways to compute the element offset. | |
1a4d82fc | 2469 | const StructLayout *Layout = nullptr; |
223e47cc LB |
2470 | uint64_t ArrayEltBitOffset = 0; |
2471 | if (StructType *EltSTy = dyn_cast<StructType>(AllocaEltTy)) { | |
1a4d82fc | 2472 | Layout = DL->getStructLayout(EltSTy); |
223e47cc LB |
2473 | } else { |
2474 | Type *ArrayEltTy = cast<ArrayType>(AllocaEltTy)->getElementType(); | |
1a4d82fc | 2475 | ArrayEltBitOffset = DL->getTypeAllocSizeInBits(ArrayEltTy); |
223e47cc LB |
2476 | } |
2477 | ||
2478 | Value *ResultVal = | |
2479 | Constant::getNullValue(IntegerType::get(LI->getContext(), AllocaSizeBits)); | |
2480 | ||
2481 | for (unsigned i = 0, e = NewElts.size(); i != e; ++i) { | |
2482 | // Load the value from the alloca. If the NewElt is an aggregate, cast | |
2483 | // the pointer to an integer of the same size before doing the load. | |
2484 | Value *SrcField = NewElts[i]; | |
2485 | Type *FieldTy = | |
2486 | cast<PointerType>(SrcField->getType())->getElementType(); | |
1a4d82fc | 2487 | uint64_t FieldSizeBits = DL->getTypeSizeInBits(FieldTy); |
223e47cc LB |
2488 | |
2489 | // Ignore zero sized fields like {}, they obviously contain no data. | |
2490 | if (FieldSizeBits == 0) continue; | |
2491 | ||
2492 | IntegerType *FieldIntTy = IntegerType::get(LI->getContext(), | |
2493 | FieldSizeBits); | |
2494 | if (!FieldTy->isIntegerTy() && !FieldTy->isFloatingPointTy() && | |
2495 | !FieldTy->isVectorTy()) | |
2496 | SrcField = new BitCastInst(SrcField, | |
2497 | PointerType::getUnqual(FieldIntTy), | |
2498 | "", LI); | |
2499 | SrcField = new LoadInst(SrcField, "sroa.load.elt", LI); | |
2500 | ||
2501 | // If SrcField is a fp or vector of the right size but that isn't an | |
2502 | // integer type, bitcast to an integer so we can shift it. | |
2503 | if (SrcField->getType() != FieldIntTy) | |
2504 | SrcField = new BitCastInst(SrcField, FieldIntTy, "", LI); | |
2505 | ||
2506 | // Zero extend the field to be the same size as the final alloca so that | |
2507 | // we can shift and insert it. | |
2508 | if (SrcField->getType() != ResultVal->getType()) | |
2509 | SrcField = new ZExtInst(SrcField, ResultVal->getType(), "", LI); | |
2510 | ||
2511 | // Determine the number of bits to shift SrcField. | |
2512 | uint64_t Shift; | |
2513 | if (Layout) // Struct case. | |
2514 | Shift = Layout->getElementOffsetInBits(i); | |
2515 | else // Array case. | |
2516 | Shift = i*ArrayEltBitOffset; | |
2517 | ||
1a4d82fc | 2518 | if (DL->isBigEndian()) |
223e47cc LB |
2519 | Shift = AllocaSizeBits-Shift-FieldIntTy->getBitWidth(); |
2520 | ||
2521 | if (Shift) { | |
2522 | Value *ShiftVal = ConstantInt::get(SrcField->getType(), Shift); | |
2523 | SrcField = BinaryOperator::CreateShl(SrcField, ShiftVal, "", LI); | |
2524 | } | |
2525 | ||
2526 | // Don't create an 'or x, 0' on the first iteration. | |
2527 | if (!isa<Constant>(ResultVal) || | |
2528 | !cast<Constant>(ResultVal)->isNullValue()) | |
2529 | ResultVal = BinaryOperator::CreateOr(SrcField, ResultVal, "", LI); | |
2530 | else | |
2531 | ResultVal = SrcField; | |
2532 | } | |
2533 | ||
2534 | // Handle tail padding by truncating the result | |
1a4d82fc | 2535 | if (DL->getTypeSizeInBits(LI->getType()) != AllocaSizeBits) |
223e47cc LB |
2536 | ResultVal = new TruncInst(ResultVal, LI->getType(), "", LI); |
2537 | ||
2538 | LI->replaceAllUsesWith(ResultVal); | |
2539 | DeadInsts.push_back(LI); | |
2540 | } | |
2541 | ||
2542 | /// HasPadding - Return true if the specified type has any structure or | |
2543 | /// alignment padding in between the elements that would be split apart | |
2544 | /// by SROA; return false otherwise. | |
1a4d82fc | 2545 | static bool HasPadding(Type *Ty, const DataLayout &DL) { |
223e47cc LB |
2546 | if (ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { |
2547 | Ty = ATy->getElementType(); | |
1a4d82fc | 2548 | return DL.getTypeSizeInBits(Ty) != DL.getTypeAllocSizeInBits(Ty); |
223e47cc LB |
2549 | } |
2550 | ||
2551 | // SROA currently handles only Arrays and Structs. | |
2552 | StructType *STy = cast<StructType>(Ty); | |
1a4d82fc | 2553 | const StructLayout *SL = DL.getStructLayout(STy); |
223e47cc LB |
2554 | unsigned PrevFieldBitOffset = 0; |
2555 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { | |
2556 | unsigned FieldBitOffset = SL->getElementOffsetInBits(i); | |
2557 | ||
2558 | // Check to see if there is any padding between this element and the | |
2559 | // previous one. | |
2560 | if (i) { | |
2561 | unsigned PrevFieldEnd = | |
1a4d82fc | 2562 | PrevFieldBitOffset+DL.getTypeSizeInBits(STy->getElementType(i-1)); |
223e47cc LB |
2563 | if (PrevFieldEnd < FieldBitOffset) |
2564 | return true; | |
2565 | } | |
2566 | PrevFieldBitOffset = FieldBitOffset; | |
2567 | } | |
2568 | // Check for tail padding. | |
2569 | if (unsigned EltCount = STy->getNumElements()) { | |
2570 | unsigned PrevFieldEnd = PrevFieldBitOffset + | |
1a4d82fc | 2571 | DL.getTypeSizeInBits(STy->getElementType(EltCount-1)); |
223e47cc LB |
2572 | if (PrevFieldEnd < SL->getSizeInBits()) |
2573 | return true; | |
2574 | } | |
2575 | return false; | |
2576 | } | |
2577 | ||
2578 | /// isSafeStructAllocaToScalarRepl - Check to see if the specified allocation of | |
2579 | /// an aggregate can be broken down into elements. Return 0 if not, 3 if safe, | |
2580 | /// or 1 if safe after canonicalization has been performed. | |
2581 | bool SROA::isSafeAllocaToScalarRepl(AllocaInst *AI) { | |
2582 | // Loop over the use list of the alloca. We can only transform it if all of | |
2583 | // the users are safe to transform. | |
2584 | AllocaInfo Info(AI); | |
2585 | ||
2586 | isSafeForScalarRepl(AI, 0, Info); | |
2587 | if (Info.isUnsafe) { | |
2588 | DEBUG(dbgs() << "Cannot transform: " << *AI << '\n'); | |
2589 | return false; | |
2590 | } | |
2591 | ||
2592 | // Okay, we know all the users are promotable. If the aggregate is a memcpy | |
2593 | // source and destination, we have to be careful. In particular, the memcpy | |
2594 | // could be moving around elements that live in structure padding of the LLVM | |
2595 | // types, but may actually be used. In these cases, we refuse to promote the | |
2596 | // struct. | |
2597 | if (Info.isMemCpySrc && Info.isMemCpyDst && | |
1a4d82fc | 2598 | HasPadding(AI->getAllocatedType(), *DL)) |
223e47cc LB |
2599 | return false; |
2600 | ||
2601 | // If the alloca never has an access to just *part* of it, but is accessed | |
2602 | // via loads and stores, then we should use ConvertToScalarInfo to promote | |
2603 | // the alloca instead of promoting each piece at a time and inserting fission | |
2604 | // and fusion code. | |
2605 | if (!Info.hasSubelementAccess && Info.hasALoadOrStore) { | |
2606 | // If the struct/array just has one element, use basic SRoA. | |
2607 | if (StructType *ST = dyn_cast<StructType>(AI->getAllocatedType())) { | |
2608 | if (ST->getNumElements() > 1) return false; | |
2609 | } else { | |
2610 | if (cast<ArrayType>(AI->getAllocatedType())->getNumElements() > 1) | |
2611 | return false; | |
2612 | } | |
2613 | } | |
2614 | ||
2615 | return true; | |
2616 | } |