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223e47cc LB |
1 | //===- GlobalOpt.cpp - Optimize Global Variables --------------------------===// |
2 | // | |
3 | // The LLVM Compiler Infrastructure | |
4 | // | |
5 | // This file is distributed under the University of Illinois Open Source | |
6 | // License. See LICENSE.TXT for details. | |
7 | // | |
8 | //===----------------------------------------------------------------------===// | |
9 | // | |
10 | // This pass transforms simple global variables that never have their address | |
11 | // taken. If obviously true, it marks read/write globals as constant, deletes | |
12 | // variables only stored to, etc. | |
13 | // | |
14 | //===----------------------------------------------------------------------===// | |
15 | ||
223e47cc | 16 | #include "llvm/Transforms/IPO.h" |
970d7e83 LB |
17 | #include "llvm/ADT/DenseMap.h" |
18 | #include "llvm/ADT/STLExtras.h" | |
19 | #include "llvm/ADT/SmallPtrSet.h" | |
1a4d82fc | 20 | #include "llvm/ADT/SmallSet.h" |
970d7e83 LB |
21 | #include "llvm/ADT/SmallVector.h" |
22 | #include "llvm/ADT/Statistic.h" | |
223e47cc LB |
23 | #include "llvm/Analysis/ConstantFolding.h" |
24 | #include "llvm/Analysis/MemoryBuiltins.h" | |
1a4d82fc | 25 | #include "llvm/IR/CallSite.h" |
970d7e83 LB |
26 | #include "llvm/IR/CallingConv.h" |
27 | #include "llvm/IR/Constants.h" | |
28 | #include "llvm/IR/DataLayout.h" | |
29 | #include "llvm/IR/DerivedTypes.h" | |
1a4d82fc | 30 | #include "llvm/IR/GetElementPtrTypeIterator.h" |
970d7e83 LB |
31 | #include "llvm/IR/Instructions.h" |
32 | #include "llvm/IR/IntrinsicInst.h" | |
33 | #include "llvm/IR/Module.h" | |
34 | #include "llvm/IR/Operator.h" | |
1a4d82fc | 35 | #include "llvm/IR/ValueHandle.h" |
970d7e83 | 36 | #include "llvm/Pass.h" |
223e47cc LB |
37 | #include "llvm/Support/Debug.h" |
38 | #include "llvm/Support/ErrorHandling.h" | |
223e47cc LB |
39 | #include "llvm/Support/MathExtras.h" |
40 | #include "llvm/Support/raw_ostream.h" | |
970d7e83 | 41 | #include "llvm/Target/TargetLibraryInfo.h" |
1a4d82fc JJ |
42 | #include "llvm/Transforms/Utils/CtorUtils.h" |
43 | #include "llvm/Transforms/Utils/GlobalStatus.h" | |
44 | #include "llvm/Transforms/Utils/ModuleUtils.h" | |
223e47cc | 45 | #include <algorithm> |
1a4d82fc | 46 | #include <deque> |
223e47cc LB |
47 | using namespace llvm; |
48 | ||
1a4d82fc JJ |
49 | #define DEBUG_TYPE "globalopt" |
50 | ||
223e47cc LB |
51 | STATISTIC(NumMarked , "Number of globals marked constant"); |
52 | STATISTIC(NumUnnamed , "Number of globals marked unnamed_addr"); | |
53 | STATISTIC(NumSRA , "Number of aggregate globals broken into scalars"); | |
54 | STATISTIC(NumHeapSRA , "Number of heap objects SRA'd"); | |
55 | STATISTIC(NumSubstitute,"Number of globals with initializers stored into them"); | |
56 | STATISTIC(NumDeleted , "Number of globals deleted"); | |
57 | STATISTIC(NumFnDeleted , "Number of functions deleted"); | |
58 | STATISTIC(NumGlobUses , "Number of global uses devirtualized"); | |
59 | STATISTIC(NumLocalized , "Number of globals localized"); | |
60 | STATISTIC(NumShrunkToBool , "Number of global vars shrunk to booleans"); | |
61 | STATISTIC(NumFastCallFns , "Number of functions converted to fastcc"); | |
62 | STATISTIC(NumCtorsEvaluated, "Number of static ctors evaluated"); | |
63 | STATISTIC(NumNestRemoved , "Number of nest attributes removed"); | |
64 | STATISTIC(NumAliasesResolved, "Number of global aliases resolved"); | |
65 | STATISTIC(NumAliasesRemoved, "Number of global aliases eliminated"); | |
66 | STATISTIC(NumCXXDtorsRemoved, "Number of global C++ destructors removed"); | |
67 | ||
68 | namespace { | |
223e47cc | 69 | struct GlobalOpt : public ModulePass { |
1a4d82fc | 70 | void getAnalysisUsage(AnalysisUsage &AU) const override { |
223e47cc LB |
71 | AU.addRequired<TargetLibraryInfo>(); |
72 | } | |
73 | static char ID; // Pass identification, replacement for typeid | |
74 | GlobalOpt() : ModulePass(ID) { | |
75 | initializeGlobalOptPass(*PassRegistry::getPassRegistry()); | |
76 | } | |
77 | ||
1a4d82fc | 78 | bool runOnModule(Module &M) override; |
223e47cc LB |
79 | |
80 | private: | |
223e47cc LB |
81 | bool OptimizeFunctions(Module &M); |
82 | bool OptimizeGlobalVars(Module &M); | |
83 | bool OptimizeGlobalAliases(Module &M); | |
223e47cc LB |
84 | bool ProcessGlobal(GlobalVariable *GV,Module::global_iterator &GVI); |
85 | bool ProcessInternalGlobal(GlobalVariable *GV,Module::global_iterator &GVI, | |
223e47cc LB |
86 | const GlobalStatus &GS); |
87 | bool OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn); | |
88 | ||
1a4d82fc | 89 | const DataLayout *DL; |
223e47cc | 90 | TargetLibraryInfo *TLI; |
85aaf69f | 91 | SmallSet<const Comdat *, 8> NotDiscardableComdats; |
223e47cc LB |
92 | }; |
93 | } | |
94 | ||
95 | char GlobalOpt::ID = 0; | |
96 | INITIALIZE_PASS_BEGIN(GlobalOpt, "globalopt", | |
97 | "Global Variable Optimizer", false, false) | |
98 | INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) | |
99 | INITIALIZE_PASS_END(GlobalOpt, "globalopt", | |
100 | "Global Variable Optimizer", false, false) | |
101 | ||
102 | ModulePass *llvm::createGlobalOptimizerPass() { return new GlobalOpt(); } | |
103 | ||
223e47cc LB |
104 | /// isLeakCheckerRoot - Is this global variable possibly used by a leak checker |
105 | /// as a root? If so, we might not really want to eliminate the stores to it. | |
106 | static bool isLeakCheckerRoot(GlobalVariable *GV) { | |
107 | // A global variable is a root if it is a pointer, or could plausibly contain | |
108 | // a pointer. There are two challenges; one is that we could have a struct | |
109 | // the has an inner member which is a pointer. We recurse through the type to | |
110 | // detect these (up to a point). The other is that we may actually be a union | |
111 | // of a pointer and another type, and so our LLVM type is an integer which | |
112 | // gets converted into a pointer, or our type is an [i8 x #] with a pointer | |
113 | // potentially contained here. | |
114 | ||
115 | if (GV->hasPrivateLinkage()) | |
116 | return false; | |
117 | ||
118 | SmallVector<Type *, 4> Types; | |
119 | Types.push_back(cast<PointerType>(GV->getType())->getElementType()); | |
120 | ||
121 | unsigned Limit = 20; | |
122 | do { | |
123 | Type *Ty = Types.pop_back_val(); | |
124 | switch (Ty->getTypeID()) { | |
125 | default: break; | |
126 | case Type::PointerTyID: return true; | |
127 | case Type::ArrayTyID: | |
128 | case Type::VectorTyID: { | |
129 | SequentialType *STy = cast<SequentialType>(Ty); | |
130 | Types.push_back(STy->getElementType()); | |
131 | break; | |
132 | } | |
133 | case Type::StructTyID: { | |
134 | StructType *STy = cast<StructType>(Ty); | |
135 | if (STy->isOpaque()) return true; | |
136 | for (StructType::element_iterator I = STy->element_begin(), | |
137 | E = STy->element_end(); I != E; ++I) { | |
138 | Type *InnerTy = *I; | |
139 | if (isa<PointerType>(InnerTy)) return true; | |
140 | if (isa<CompositeType>(InnerTy)) | |
141 | Types.push_back(InnerTy); | |
142 | } | |
143 | break; | |
144 | } | |
145 | } | |
146 | if (--Limit == 0) return true; | |
147 | } while (!Types.empty()); | |
148 | return false; | |
149 | } | |
150 | ||
151 | /// Given a value that is stored to a global but never read, determine whether | |
152 | /// it's safe to remove the store and the chain of computation that feeds the | |
153 | /// store. | |
154 | static bool IsSafeComputationToRemove(Value *V, const TargetLibraryInfo *TLI) { | |
155 | do { | |
156 | if (isa<Constant>(V)) | |
157 | return true; | |
158 | if (!V->hasOneUse()) | |
159 | return false; | |
160 | if (isa<LoadInst>(V) || isa<InvokeInst>(V) || isa<Argument>(V) || | |
161 | isa<GlobalValue>(V)) | |
162 | return false; | |
163 | if (isAllocationFn(V, TLI)) | |
164 | return true; | |
165 | ||
166 | Instruction *I = cast<Instruction>(V); | |
167 | if (I->mayHaveSideEffects()) | |
168 | return false; | |
169 | if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) { | |
170 | if (!GEP->hasAllConstantIndices()) | |
171 | return false; | |
172 | } else if (I->getNumOperands() != 1) { | |
173 | return false; | |
174 | } | |
175 | ||
176 | V = I->getOperand(0); | |
177 | } while (1); | |
178 | } | |
179 | ||
180 | /// CleanupPointerRootUsers - This GV is a pointer root. Loop over all users | |
181 | /// of the global and clean up any that obviously don't assign the global a | |
182 | /// value that isn't dynamically allocated. | |
183 | /// | |
184 | static bool CleanupPointerRootUsers(GlobalVariable *GV, | |
185 | const TargetLibraryInfo *TLI) { | |
186 | // A brief explanation of leak checkers. The goal is to find bugs where | |
187 | // pointers are forgotten, causing an accumulating growth in memory | |
188 | // usage over time. The common strategy for leak checkers is to whitelist the | |
189 | // memory pointed to by globals at exit. This is popular because it also | |
190 | // solves another problem where the main thread of a C++ program may shut down | |
191 | // before other threads that are still expecting to use those globals. To | |
192 | // handle that case, we expect the program may create a singleton and never | |
193 | // destroy it. | |
194 | ||
195 | bool Changed = false; | |
196 | ||
197 | // If Dead[n].first is the only use of a malloc result, we can delete its | |
198 | // chain of computation and the store to the global in Dead[n].second. | |
199 | SmallVector<std::pair<Instruction *, Instruction *>, 32> Dead; | |
200 | ||
201 | // Constants can't be pointers to dynamically allocated memory. | |
1a4d82fc | 202 | for (Value::user_iterator UI = GV->user_begin(), E = GV->user_end(); |
223e47cc LB |
203 | UI != E;) { |
204 | User *U = *UI++; | |
205 | if (StoreInst *SI = dyn_cast<StoreInst>(U)) { | |
206 | Value *V = SI->getValueOperand(); | |
207 | if (isa<Constant>(V)) { | |
208 | Changed = true; | |
209 | SI->eraseFromParent(); | |
210 | } else if (Instruction *I = dyn_cast<Instruction>(V)) { | |
211 | if (I->hasOneUse()) | |
212 | Dead.push_back(std::make_pair(I, SI)); | |
213 | } | |
214 | } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(U)) { | |
215 | if (isa<Constant>(MSI->getValue())) { | |
216 | Changed = true; | |
217 | MSI->eraseFromParent(); | |
218 | } else if (Instruction *I = dyn_cast<Instruction>(MSI->getValue())) { | |
219 | if (I->hasOneUse()) | |
220 | Dead.push_back(std::make_pair(I, MSI)); | |
221 | } | |
222 | } else if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U)) { | |
223 | GlobalVariable *MemSrc = dyn_cast<GlobalVariable>(MTI->getSource()); | |
224 | if (MemSrc && MemSrc->isConstant()) { | |
225 | Changed = true; | |
226 | MTI->eraseFromParent(); | |
227 | } else if (Instruction *I = dyn_cast<Instruction>(MemSrc)) { | |
228 | if (I->hasOneUse()) | |
229 | Dead.push_back(std::make_pair(I, MTI)); | |
230 | } | |
231 | } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) { | |
232 | if (CE->use_empty()) { | |
233 | CE->destroyConstant(); | |
234 | Changed = true; | |
235 | } | |
236 | } else if (Constant *C = dyn_cast<Constant>(U)) { | |
1a4d82fc | 237 | if (isSafeToDestroyConstant(C)) { |
223e47cc LB |
238 | C->destroyConstant(); |
239 | // This could have invalidated UI, start over from scratch. | |
240 | Dead.clear(); | |
241 | CleanupPointerRootUsers(GV, TLI); | |
242 | return true; | |
243 | } | |
244 | } | |
245 | } | |
246 | ||
247 | for (int i = 0, e = Dead.size(); i != e; ++i) { | |
248 | if (IsSafeComputationToRemove(Dead[i].first, TLI)) { | |
249 | Dead[i].second->eraseFromParent(); | |
250 | Instruction *I = Dead[i].first; | |
251 | do { | |
970d7e83 LB |
252 | if (isAllocationFn(I, TLI)) |
253 | break; | |
223e47cc LB |
254 | Instruction *J = dyn_cast<Instruction>(I->getOperand(0)); |
255 | if (!J) | |
256 | break; | |
257 | I->eraseFromParent(); | |
258 | I = J; | |
259 | } while (1); | |
260 | I->eraseFromParent(); | |
261 | } | |
262 | } | |
263 | ||
264 | return Changed; | |
265 | } | |
266 | ||
267 | /// CleanupConstantGlobalUsers - We just marked GV constant. Loop over all | |
268 | /// users of the global, cleaning up the obvious ones. This is largely just a | |
269 | /// quick scan over the use list to clean up the easy and obvious cruft. This | |
270 | /// returns true if it made a change. | |
271 | static bool CleanupConstantGlobalUsers(Value *V, Constant *Init, | |
1a4d82fc JJ |
272 | const DataLayout *DL, |
273 | TargetLibraryInfo *TLI) { | |
223e47cc | 274 | bool Changed = false; |
1a4d82fc JJ |
275 | // Note that we need to use a weak value handle for the worklist items. When |
276 | // we delete a constant array, we may also be holding pointer to one of its | |
277 | // elements (or an element of one of its elements if we're dealing with an | |
278 | // array of arrays) in the worklist. | |
279 | SmallVector<WeakVH, 8> WorkList(V->user_begin(), V->user_end()); | |
280 | while (!WorkList.empty()) { | |
281 | Value *UV = WorkList.pop_back_val(); | |
282 | if (!UV) | |
283 | continue; | |
284 | ||
285 | User *U = cast<User>(UV); | |
223e47cc LB |
286 | |
287 | if (LoadInst *LI = dyn_cast<LoadInst>(U)) { | |
288 | if (Init) { | |
289 | // Replace the load with the initializer. | |
290 | LI->replaceAllUsesWith(Init); | |
291 | LI->eraseFromParent(); | |
292 | Changed = true; | |
293 | } | |
294 | } else if (StoreInst *SI = dyn_cast<StoreInst>(U)) { | |
295 | // Store must be unreachable or storing Init into the global. | |
296 | SI->eraseFromParent(); | |
297 | Changed = true; | |
298 | } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) { | |
299 | if (CE->getOpcode() == Instruction::GetElementPtr) { | |
1a4d82fc | 300 | Constant *SubInit = nullptr; |
223e47cc LB |
301 | if (Init) |
302 | SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE); | |
1a4d82fc JJ |
303 | Changed |= CleanupConstantGlobalUsers(CE, SubInit, DL, TLI); |
304 | } else if ((CE->getOpcode() == Instruction::BitCast && | |
305 | CE->getType()->isPointerTy()) || | |
306 | CE->getOpcode() == Instruction::AddrSpaceCast) { | |
223e47cc | 307 | // Pointer cast, delete any stores and memsets to the global. |
1a4d82fc | 308 | Changed |= CleanupConstantGlobalUsers(CE, nullptr, DL, TLI); |
223e47cc LB |
309 | } |
310 | ||
311 | if (CE->use_empty()) { | |
312 | CE->destroyConstant(); | |
313 | Changed = true; | |
314 | } | |
315 | } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(U)) { | |
316 | // Do not transform "gepinst (gep constexpr (GV))" here, because forming | |
317 | // "gepconstexpr (gep constexpr (GV))" will cause the two gep's to fold | |
318 | // and will invalidate our notion of what Init is. | |
1a4d82fc | 319 | Constant *SubInit = nullptr; |
223e47cc LB |
320 | if (!isa<ConstantExpr>(GEP->getOperand(0))) { |
321 | ConstantExpr *CE = | |
1a4d82fc | 322 | dyn_cast_or_null<ConstantExpr>(ConstantFoldInstruction(GEP, DL, TLI)); |
223e47cc LB |
323 | if (Init && CE && CE->getOpcode() == Instruction::GetElementPtr) |
324 | SubInit = ConstantFoldLoadThroughGEPConstantExpr(Init, CE); | |
325 | ||
326 | // If the initializer is an all-null value and we have an inbounds GEP, | |
327 | // we already know what the result of any load from that GEP is. | |
328 | // TODO: Handle splats. | |
329 | if (Init && isa<ConstantAggregateZero>(Init) && GEP->isInBounds()) | |
330 | SubInit = Constant::getNullValue(GEP->getType()->getElementType()); | |
331 | } | |
1a4d82fc | 332 | Changed |= CleanupConstantGlobalUsers(GEP, SubInit, DL, TLI); |
223e47cc LB |
333 | |
334 | if (GEP->use_empty()) { | |
335 | GEP->eraseFromParent(); | |
336 | Changed = true; | |
337 | } | |
338 | } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(U)) { // memset/cpy/mv | |
339 | if (MI->getRawDest() == V) { | |
340 | MI->eraseFromParent(); | |
341 | Changed = true; | |
342 | } | |
343 | ||
344 | } else if (Constant *C = dyn_cast<Constant>(U)) { | |
345 | // If we have a chain of dead constantexprs or other things dangling from | |
346 | // us, and if they are all dead, nuke them without remorse. | |
1a4d82fc | 347 | if (isSafeToDestroyConstant(C)) { |
223e47cc | 348 | C->destroyConstant(); |
1a4d82fc | 349 | CleanupConstantGlobalUsers(V, Init, DL, TLI); |
223e47cc LB |
350 | return true; |
351 | } | |
352 | } | |
353 | } | |
354 | return Changed; | |
355 | } | |
356 | ||
357 | /// isSafeSROAElementUse - Return true if the specified instruction is a safe | |
358 | /// user of a derived expression from a global that we want to SROA. | |
359 | static bool isSafeSROAElementUse(Value *V) { | |
360 | // We might have a dead and dangling constant hanging off of here. | |
361 | if (Constant *C = dyn_cast<Constant>(V)) | |
1a4d82fc | 362 | return isSafeToDestroyConstant(C); |
223e47cc LB |
363 | |
364 | Instruction *I = dyn_cast<Instruction>(V); | |
365 | if (!I) return false; | |
366 | ||
367 | // Loads are ok. | |
368 | if (isa<LoadInst>(I)) return true; | |
369 | ||
370 | // Stores *to* the pointer are ok. | |
371 | if (StoreInst *SI = dyn_cast<StoreInst>(I)) | |
372 | return SI->getOperand(0) != V; | |
373 | ||
374 | // Otherwise, it must be a GEP. | |
375 | GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I); | |
1a4d82fc | 376 | if (!GEPI) return false; |
223e47cc LB |
377 | |
378 | if (GEPI->getNumOperands() < 3 || !isa<Constant>(GEPI->getOperand(1)) || | |
379 | !cast<Constant>(GEPI->getOperand(1))->isNullValue()) | |
380 | return false; | |
381 | ||
1a4d82fc JJ |
382 | for (User *U : GEPI->users()) |
383 | if (!isSafeSROAElementUse(U)) | |
223e47cc LB |
384 | return false; |
385 | return true; | |
386 | } | |
387 | ||
388 | ||
389 | /// IsUserOfGlobalSafeForSRA - U is a direct user of the specified global value. | |
390 | /// Look at it and its uses and decide whether it is safe to SROA this global. | |
391 | /// | |
392 | static bool IsUserOfGlobalSafeForSRA(User *U, GlobalValue *GV) { | |
393 | // The user of the global must be a GEP Inst or a ConstantExpr GEP. | |
394 | if (!isa<GetElementPtrInst>(U) && | |
395 | (!isa<ConstantExpr>(U) || | |
396 | cast<ConstantExpr>(U)->getOpcode() != Instruction::GetElementPtr)) | |
397 | return false; | |
398 | ||
399 | // Check to see if this ConstantExpr GEP is SRA'able. In particular, we | |
400 | // don't like < 3 operand CE's, and we don't like non-constant integer | |
401 | // indices. This enforces that all uses are 'gep GV, 0, C, ...' for some | |
402 | // value of C. | |
403 | if (U->getNumOperands() < 3 || !isa<Constant>(U->getOperand(1)) || | |
404 | !cast<Constant>(U->getOperand(1))->isNullValue() || | |
405 | !isa<ConstantInt>(U->getOperand(2))) | |
406 | return false; | |
407 | ||
408 | gep_type_iterator GEPI = gep_type_begin(U), E = gep_type_end(U); | |
409 | ++GEPI; // Skip over the pointer index. | |
410 | ||
411 | // If this is a use of an array allocation, do a bit more checking for sanity. | |
412 | if (ArrayType *AT = dyn_cast<ArrayType>(*GEPI)) { | |
413 | uint64_t NumElements = AT->getNumElements(); | |
414 | ConstantInt *Idx = cast<ConstantInt>(U->getOperand(2)); | |
415 | ||
416 | // Check to make sure that index falls within the array. If not, | |
417 | // something funny is going on, so we won't do the optimization. | |
418 | // | |
419 | if (Idx->getZExtValue() >= NumElements) | |
420 | return false; | |
421 | ||
422 | // We cannot scalar repl this level of the array unless any array | |
423 | // sub-indices are in-range constants. In particular, consider: | |
424 | // A[0][i]. We cannot know that the user isn't doing invalid things like | |
425 | // allowing i to index an out-of-range subscript that accesses A[1]. | |
426 | // | |
427 | // Scalar replacing *just* the outer index of the array is probably not | |
428 | // going to be a win anyway, so just give up. | |
429 | for (++GEPI; // Skip array index. | |
430 | GEPI != E; | |
431 | ++GEPI) { | |
432 | uint64_t NumElements; | |
433 | if (ArrayType *SubArrayTy = dyn_cast<ArrayType>(*GEPI)) | |
434 | NumElements = SubArrayTy->getNumElements(); | |
435 | else if (VectorType *SubVectorTy = dyn_cast<VectorType>(*GEPI)) | |
436 | NumElements = SubVectorTy->getNumElements(); | |
437 | else { | |
438 | assert((*GEPI)->isStructTy() && | |
439 | "Indexed GEP type is not array, vector, or struct!"); | |
440 | continue; | |
441 | } | |
442 | ||
443 | ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPI.getOperand()); | |
444 | if (!IdxVal || IdxVal->getZExtValue() >= NumElements) | |
445 | return false; | |
446 | } | |
447 | } | |
448 | ||
1a4d82fc JJ |
449 | for (User *UU : U->users()) |
450 | if (!isSafeSROAElementUse(UU)) | |
223e47cc | 451 | return false; |
1a4d82fc | 452 | |
223e47cc LB |
453 | return true; |
454 | } | |
455 | ||
456 | /// GlobalUsersSafeToSRA - Look at all uses of the global and decide whether it | |
457 | /// is safe for us to perform this transformation. | |
458 | /// | |
459 | static bool GlobalUsersSafeToSRA(GlobalValue *GV) { | |
1a4d82fc JJ |
460 | for (User *U : GV->users()) |
461 | if (!IsUserOfGlobalSafeForSRA(U, GV)) | |
223e47cc | 462 | return false; |
1a4d82fc | 463 | |
223e47cc LB |
464 | return true; |
465 | } | |
466 | ||
467 | ||
468 | /// SRAGlobal - Perform scalar replacement of aggregates on the specified global | |
469 | /// variable. This opens the door for other optimizations by exposing the | |
470 | /// behavior of the program in a more fine-grained way. We have determined that | |
471 | /// this transformation is safe already. We return the first global variable we | |
472 | /// insert so that the caller can reprocess it. | |
1a4d82fc | 473 | static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) { |
223e47cc LB |
474 | // Make sure this global only has simple uses that we can SRA. |
475 | if (!GlobalUsersSafeToSRA(GV)) | |
1a4d82fc | 476 | return nullptr; |
223e47cc LB |
477 | |
478 | assert(GV->hasLocalLinkage() && !GV->isConstant()); | |
479 | Constant *Init = GV->getInitializer(); | |
480 | Type *Ty = Init->getType(); | |
481 | ||
482 | std::vector<GlobalVariable*> NewGlobals; | |
483 | Module::GlobalListType &Globals = GV->getParent()->getGlobalList(); | |
484 | ||
485 | // Get the alignment of the global, either explicit or target-specific. | |
486 | unsigned StartAlignment = GV->getAlignment(); | |
487 | if (StartAlignment == 0) | |
1a4d82fc | 488 | StartAlignment = DL.getABITypeAlignment(GV->getType()); |
223e47cc LB |
489 | |
490 | if (StructType *STy = dyn_cast<StructType>(Ty)) { | |
491 | NewGlobals.reserve(STy->getNumElements()); | |
1a4d82fc | 492 | const StructLayout &Layout = *DL.getStructLayout(STy); |
223e47cc LB |
493 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) { |
494 | Constant *In = Init->getAggregateElement(i); | |
495 | assert(In && "Couldn't get element of initializer?"); | |
496 | GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false, | |
497 | GlobalVariable::InternalLinkage, | |
498 | In, GV->getName()+"."+Twine(i), | |
499 | GV->getThreadLocalMode(), | |
500 | GV->getType()->getAddressSpace()); | |
501 | Globals.insert(GV, NGV); | |
502 | NewGlobals.push_back(NGV); | |
503 | ||
504 | // Calculate the known alignment of the field. If the original aggregate | |
505 | // had 256 byte alignment for example, something might depend on that: | |
506 | // propagate info to each field. | |
507 | uint64_t FieldOffset = Layout.getElementOffset(i); | |
508 | unsigned NewAlign = (unsigned)MinAlign(StartAlignment, FieldOffset); | |
1a4d82fc | 509 | if (NewAlign > DL.getABITypeAlignment(STy->getElementType(i))) |
223e47cc LB |
510 | NGV->setAlignment(NewAlign); |
511 | } | |
512 | } else if (SequentialType *STy = dyn_cast<SequentialType>(Ty)) { | |
513 | unsigned NumElements = 0; | |
514 | if (ArrayType *ATy = dyn_cast<ArrayType>(STy)) | |
515 | NumElements = ATy->getNumElements(); | |
516 | else | |
517 | NumElements = cast<VectorType>(STy)->getNumElements(); | |
518 | ||
519 | if (NumElements > 16 && GV->hasNUsesOrMore(16)) | |
1a4d82fc | 520 | return nullptr; // It's not worth it. |
223e47cc LB |
521 | NewGlobals.reserve(NumElements); |
522 | ||
1a4d82fc JJ |
523 | uint64_t EltSize = DL.getTypeAllocSize(STy->getElementType()); |
524 | unsigned EltAlign = DL.getABITypeAlignment(STy->getElementType()); | |
223e47cc LB |
525 | for (unsigned i = 0, e = NumElements; i != e; ++i) { |
526 | Constant *In = Init->getAggregateElement(i); | |
527 | assert(In && "Couldn't get element of initializer?"); | |
528 | ||
529 | GlobalVariable *NGV = new GlobalVariable(STy->getElementType(), false, | |
530 | GlobalVariable::InternalLinkage, | |
531 | In, GV->getName()+"."+Twine(i), | |
532 | GV->getThreadLocalMode(), | |
533 | GV->getType()->getAddressSpace()); | |
534 | Globals.insert(GV, NGV); | |
535 | NewGlobals.push_back(NGV); | |
536 | ||
537 | // Calculate the known alignment of the field. If the original aggregate | |
538 | // had 256 byte alignment for example, something might depend on that: | |
539 | // propagate info to each field. | |
540 | unsigned NewAlign = (unsigned)MinAlign(StartAlignment, EltSize*i); | |
541 | if (NewAlign > EltAlign) | |
542 | NGV->setAlignment(NewAlign); | |
543 | } | |
544 | } | |
545 | ||
546 | if (NewGlobals.empty()) | |
1a4d82fc | 547 | return nullptr; |
223e47cc LB |
548 | |
549 | DEBUG(dbgs() << "PERFORMING GLOBAL SRA ON: " << *GV); | |
550 | ||
551 | Constant *NullInt =Constant::getNullValue(Type::getInt32Ty(GV->getContext())); | |
552 | ||
553 | // Loop over all of the uses of the global, replacing the constantexpr geps, | |
554 | // with smaller constantexpr geps or direct references. | |
555 | while (!GV->use_empty()) { | |
1a4d82fc | 556 | User *GEP = GV->user_back(); |
223e47cc LB |
557 | assert(((isa<ConstantExpr>(GEP) && |
558 | cast<ConstantExpr>(GEP)->getOpcode()==Instruction::GetElementPtr)|| | |
559 | isa<GetElementPtrInst>(GEP)) && "NonGEP CE's are not SRAable!"); | |
560 | ||
561 | // Ignore the 1th operand, which has to be zero or else the program is quite | |
562 | // broken (undefined). Get the 2nd operand, which is the structure or array | |
563 | // index. | |
564 | unsigned Val = cast<ConstantInt>(GEP->getOperand(2))->getZExtValue(); | |
565 | if (Val >= NewGlobals.size()) Val = 0; // Out of bound array access. | |
566 | ||
567 | Value *NewPtr = NewGlobals[Val]; | |
568 | ||
569 | // Form a shorter GEP if needed. | |
570 | if (GEP->getNumOperands() > 3) { | |
571 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP)) { | |
572 | SmallVector<Constant*, 8> Idxs; | |
573 | Idxs.push_back(NullInt); | |
574 | for (unsigned i = 3, e = CE->getNumOperands(); i != e; ++i) | |
575 | Idxs.push_back(CE->getOperand(i)); | |
576 | NewPtr = ConstantExpr::getGetElementPtr(cast<Constant>(NewPtr), Idxs); | |
577 | } else { | |
578 | GetElementPtrInst *GEPI = cast<GetElementPtrInst>(GEP); | |
579 | SmallVector<Value*, 8> Idxs; | |
580 | Idxs.push_back(NullInt); | |
581 | for (unsigned i = 3, e = GEPI->getNumOperands(); i != e; ++i) | |
582 | Idxs.push_back(GEPI->getOperand(i)); | |
583 | NewPtr = GetElementPtrInst::Create(NewPtr, Idxs, | |
584 | GEPI->getName()+"."+Twine(Val),GEPI); | |
585 | } | |
586 | } | |
587 | GEP->replaceAllUsesWith(NewPtr); | |
588 | ||
589 | if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(GEP)) | |
590 | GEPI->eraseFromParent(); | |
591 | else | |
592 | cast<ConstantExpr>(GEP)->destroyConstant(); | |
593 | } | |
594 | ||
595 | // Delete the old global, now that it is dead. | |
596 | Globals.erase(GV); | |
597 | ++NumSRA; | |
598 | ||
599 | // Loop over the new globals array deleting any globals that are obviously | |
600 | // dead. This can arise due to scalarization of a structure or an array that | |
601 | // has elements that are dead. | |
602 | unsigned FirstGlobal = 0; | |
603 | for (unsigned i = 0, e = NewGlobals.size(); i != e; ++i) | |
604 | if (NewGlobals[i]->use_empty()) { | |
605 | Globals.erase(NewGlobals[i]); | |
606 | if (FirstGlobal == i) ++FirstGlobal; | |
607 | } | |
608 | ||
1a4d82fc | 609 | return FirstGlobal != NewGlobals.size() ? NewGlobals[FirstGlobal] : nullptr; |
223e47cc LB |
610 | } |
611 | ||
612 | /// AllUsesOfValueWillTrapIfNull - Return true if all users of the specified | |
613 | /// value will trap if the value is dynamically null. PHIs keeps track of any | |
614 | /// phi nodes we've seen to avoid reprocessing them. | |
615 | static bool AllUsesOfValueWillTrapIfNull(const Value *V, | |
1a4d82fc JJ |
616 | SmallPtrSetImpl<const PHINode*> &PHIs) { |
617 | for (const User *U : V->users()) | |
223e47cc LB |
618 | if (isa<LoadInst>(U)) { |
619 | // Will trap. | |
620 | } else if (const StoreInst *SI = dyn_cast<StoreInst>(U)) { | |
621 | if (SI->getOperand(0) == V) { | |
622 | //cerr << "NONTRAPPING USE: " << *U; | |
623 | return false; // Storing the value. | |
624 | } | |
625 | } else if (const CallInst *CI = dyn_cast<CallInst>(U)) { | |
626 | if (CI->getCalledValue() != V) { | |
627 | //cerr << "NONTRAPPING USE: " << *U; | |
628 | return false; // Not calling the ptr | |
629 | } | |
630 | } else if (const InvokeInst *II = dyn_cast<InvokeInst>(U)) { | |
631 | if (II->getCalledValue() != V) { | |
632 | //cerr << "NONTRAPPING USE: " << *U; | |
633 | return false; // Not calling the ptr | |
634 | } | |
635 | } else if (const BitCastInst *CI = dyn_cast<BitCastInst>(U)) { | |
636 | if (!AllUsesOfValueWillTrapIfNull(CI, PHIs)) return false; | |
637 | } else if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) { | |
638 | if (!AllUsesOfValueWillTrapIfNull(GEPI, PHIs)) return false; | |
639 | } else if (const PHINode *PN = dyn_cast<PHINode>(U)) { | |
640 | // If we've already seen this phi node, ignore it, it has already been | |
641 | // checked. | |
85aaf69f | 642 | if (PHIs.insert(PN).second && !AllUsesOfValueWillTrapIfNull(PN, PHIs)) |
223e47cc LB |
643 | return false; |
644 | } else if (isa<ICmpInst>(U) && | |
1a4d82fc | 645 | isa<ConstantPointerNull>(U->getOperand(1))) { |
223e47cc LB |
646 | // Ignore icmp X, null |
647 | } else { | |
648 | //cerr << "NONTRAPPING USE: " << *U; | |
649 | return false; | |
650 | } | |
1a4d82fc | 651 | |
223e47cc LB |
652 | return true; |
653 | } | |
654 | ||
655 | /// AllUsesOfLoadedValueWillTrapIfNull - Return true if all uses of any loads | |
656 | /// from GV will trap if the loaded value is null. Note that this also permits | |
657 | /// comparisons of the loaded value against null, as a special case. | |
658 | static bool AllUsesOfLoadedValueWillTrapIfNull(const GlobalVariable *GV) { | |
1a4d82fc | 659 | for (const User *U : GV->users()) |
223e47cc LB |
660 | if (const LoadInst *LI = dyn_cast<LoadInst>(U)) { |
661 | SmallPtrSet<const PHINode*, 8> PHIs; | |
662 | if (!AllUsesOfValueWillTrapIfNull(LI, PHIs)) | |
663 | return false; | |
664 | } else if (isa<StoreInst>(U)) { | |
665 | // Ignore stores to the global. | |
666 | } else { | |
667 | // We don't know or understand this user, bail out. | |
668 | //cerr << "UNKNOWN USER OF GLOBAL!: " << *U; | |
669 | return false; | |
670 | } | |
223e47cc LB |
671 | return true; |
672 | } | |
673 | ||
674 | static bool OptimizeAwayTrappingUsesOfValue(Value *V, Constant *NewV) { | |
675 | bool Changed = false; | |
1a4d82fc | 676 | for (auto UI = V->user_begin(), E = V->user_end(); UI != E; ) { |
223e47cc LB |
677 | Instruction *I = cast<Instruction>(*UI++); |
678 | if (LoadInst *LI = dyn_cast<LoadInst>(I)) { | |
679 | LI->setOperand(0, NewV); | |
680 | Changed = true; | |
681 | } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) { | |
682 | if (SI->getOperand(1) == V) { | |
683 | SI->setOperand(1, NewV); | |
684 | Changed = true; | |
685 | } | |
686 | } else if (isa<CallInst>(I) || isa<InvokeInst>(I)) { | |
687 | CallSite CS(I); | |
688 | if (CS.getCalledValue() == V) { | |
689 | // Calling through the pointer! Turn into a direct call, but be careful | |
690 | // that the pointer is not also being passed as an argument. | |
691 | CS.setCalledFunction(NewV); | |
692 | Changed = true; | |
693 | bool PassedAsArg = false; | |
694 | for (unsigned i = 0, e = CS.arg_size(); i != e; ++i) | |
695 | if (CS.getArgument(i) == V) { | |
696 | PassedAsArg = true; | |
697 | CS.setArgument(i, NewV); | |
698 | } | |
699 | ||
700 | if (PassedAsArg) { | |
701 | // Being passed as an argument also. Be careful to not invalidate UI! | |
1a4d82fc | 702 | UI = V->user_begin(); |
223e47cc LB |
703 | } |
704 | } | |
705 | } else if (CastInst *CI = dyn_cast<CastInst>(I)) { | |
706 | Changed |= OptimizeAwayTrappingUsesOfValue(CI, | |
707 | ConstantExpr::getCast(CI->getOpcode(), | |
708 | NewV, CI->getType())); | |
709 | if (CI->use_empty()) { | |
710 | Changed = true; | |
711 | CI->eraseFromParent(); | |
712 | } | |
713 | } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) { | |
714 | // Should handle GEP here. | |
715 | SmallVector<Constant*, 8> Idxs; | |
716 | Idxs.reserve(GEPI->getNumOperands()-1); | |
717 | for (User::op_iterator i = GEPI->op_begin() + 1, e = GEPI->op_end(); | |
718 | i != e; ++i) | |
719 | if (Constant *C = dyn_cast<Constant>(*i)) | |
720 | Idxs.push_back(C); | |
721 | else | |
722 | break; | |
723 | if (Idxs.size() == GEPI->getNumOperands()-1) | |
724 | Changed |= OptimizeAwayTrappingUsesOfValue(GEPI, | |
725 | ConstantExpr::getGetElementPtr(NewV, Idxs)); | |
726 | if (GEPI->use_empty()) { | |
727 | Changed = true; | |
728 | GEPI->eraseFromParent(); | |
729 | } | |
730 | } | |
731 | } | |
732 | ||
733 | return Changed; | |
734 | } | |
735 | ||
736 | ||
737 | /// OptimizeAwayTrappingUsesOfLoads - The specified global has only one non-null | |
738 | /// value stored into it. If there are uses of the loaded value that would trap | |
739 | /// if the loaded value is dynamically null, then we know that they cannot be | |
740 | /// reachable with a null optimize away the load. | |
741 | static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV, | |
1a4d82fc | 742 | const DataLayout *DL, |
223e47cc LB |
743 | TargetLibraryInfo *TLI) { |
744 | bool Changed = false; | |
745 | ||
746 | // Keep track of whether we are able to remove all the uses of the global | |
747 | // other than the store that defines it. | |
748 | bool AllNonStoreUsesGone = true; | |
749 | ||
750 | // Replace all uses of loads with uses of uses of the stored value. | |
1a4d82fc | 751 | for (Value::user_iterator GUI = GV->user_begin(), E = GV->user_end(); GUI != E;){ |
223e47cc LB |
752 | User *GlobalUser = *GUI++; |
753 | if (LoadInst *LI = dyn_cast<LoadInst>(GlobalUser)) { | |
754 | Changed |= OptimizeAwayTrappingUsesOfValue(LI, LV); | |
755 | // If we were able to delete all uses of the loads | |
756 | if (LI->use_empty()) { | |
757 | LI->eraseFromParent(); | |
758 | Changed = true; | |
759 | } else { | |
760 | AllNonStoreUsesGone = false; | |
761 | } | |
762 | } else if (isa<StoreInst>(GlobalUser)) { | |
763 | // Ignore the store that stores "LV" to the global. | |
764 | assert(GlobalUser->getOperand(1) == GV && | |
765 | "Must be storing *to* the global"); | |
766 | } else { | |
767 | AllNonStoreUsesGone = false; | |
768 | ||
769 | // If we get here we could have other crazy uses that are transitively | |
770 | // loaded. | |
771 | assert((isa<PHINode>(GlobalUser) || isa<SelectInst>(GlobalUser) || | |
772 | isa<ConstantExpr>(GlobalUser) || isa<CmpInst>(GlobalUser) || | |
773 | isa<BitCastInst>(GlobalUser) || | |
774 | isa<GetElementPtrInst>(GlobalUser)) && | |
775 | "Only expect load and stores!"); | |
776 | } | |
777 | } | |
778 | ||
779 | if (Changed) { | |
780 | DEBUG(dbgs() << "OPTIMIZED LOADS FROM STORED ONCE POINTER: " << *GV); | |
781 | ++NumGlobUses; | |
782 | } | |
783 | ||
784 | // If we nuked all of the loads, then none of the stores are needed either, | |
785 | // nor is the global. | |
786 | if (AllNonStoreUsesGone) { | |
787 | if (isLeakCheckerRoot(GV)) { | |
788 | Changed |= CleanupPointerRootUsers(GV, TLI); | |
789 | } else { | |
790 | Changed = true; | |
1a4d82fc | 791 | CleanupConstantGlobalUsers(GV, nullptr, DL, TLI); |
223e47cc LB |
792 | } |
793 | if (GV->use_empty()) { | |
794 | DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n"); | |
795 | Changed = true; | |
796 | GV->eraseFromParent(); | |
797 | ++NumDeleted; | |
798 | } | |
799 | } | |
800 | return Changed; | |
801 | } | |
802 | ||
803 | /// ConstantPropUsersOf - Walk the use list of V, constant folding all of the | |
804 | /// instructions that are foldable. | |
1a4d82fc JJ |
805 | static void ConstantPropUsersOf(Value *V, const DataLayout *DL, |
806 | TargetLibraryInfo *TLI) { | |
807 | for (Value::user_iterator UI = V->user_begin(), E = V->user_end(); UI != E; ) | |
223e47cc | 808 | if (Instruction *I = dyn_cast<Instruction>(*UI++)) |
1a4d82fc | 809 | if (Constant *NewC = ConstantFoldInstruction(I, DL, TLI)) { |
223e47cc LB |
810 | I->replaceAllUsesWith(NewC); |
811 | ||
812 | // Advance UI to the next non-I use to avoid invalidating it! | |
813 | // Instructions could multiply use V. | |
814 | while (UI != E && *UI == I) | |
815 | ++UI; | |
816 | I->eraseFromParent(); | |
817 | } | |
818 | } | |
819 | ||
820 | /// OptimizeGlobalAddressOfMalloc - This function takes the specified global | |
821 | /// variable, and transforms the program as if it always contained the result of | |
822 | /// the specified malloc. Because it is always the result of the specified | |
823 | /// malloc, there is no reason to actually DO the malloc. Instead, turn the | |
824 | /// malloc into a global, and any loads of GV as uses of the new global. | |
825 | static GlobalVariable *OptimizeGlobalAddressOfMalloc(GlobalVariable *GV, | |
826 | CallInst *CI, | |
827 | Type *AllocTy, | |
828 | ConstantInt *NElements, | |
1a4d82fc | 829 | const DataLayout *DL, |
223e47cc LB |
830 | TargetLibraryInfo *TLI) { |
831 | DEBUG(errs() << "PROMOTING GLOBAL: " << *GV << " CALL = " << *CI << '\n'); | |
832 | ||
833 | Type *GlobalType; | |
834 | if (NElements->getZExtValue() == 1) | |
835 | GlobalType = AllocTy; | |
836 | else | |
837 | // If we have an array allocation, the global variable is of an array. | |
838 | GlobalType = ArrayType::get(AllocTy, NElements->getZExtValue()); | |
839 | ||
840 | // Create the new global variable. The contents of the malloc'd memory is | |
841 | // undefined, so initialize with an undef value. | |
842 | GlobalVariable *NewGV = new GlobalVariable(*GV->getParent(), | |
843 | GlobalType, false, | |
844 | GlobalValue::InternalLinkage, | |
845 | UndefValue::get(GlobalType), | |
846 | GV->getName()+".body", | |
847 | GV, | |
848 | GV->getThreadLocalMode()); | |
849 | ||
850 | // If there are bitcast users of the malloc (which is typical, usually we have | |
851 | // a malloc + bitcast) then replace them with uses of the new global. Update | |
852 | // other users to use the global as well. | |
1a4d82fc | 853 | BitCastInst *TheBC = nullptr; |
223e47cc | 854 | while (!CI->use_empty()) { |
1a4d82fc | 855 | Instruction *User = cast<Instruction>(CI->user_back()); |
223e47cc LB |
856 | if (BitCastInst *BCI = dyn_cast<BitCastInst>(User)) { |
857 | if (BCI->getType() == NewGV->getType()) { | |
858 | BCI->replaceAllUsesWith(NewGV); | |
859 | BCI->eraseFromParent(); | |
860 | } else { | |
861 | BCI->setOperand(0, NewGV); | |
862 | } | |
863 | } else { | |
1a4d82fc | 864 | if (!TheBC) |
223e47cc LB |
865 | TheBC = new BitCastInst(NewGV, CI->getType(), "newgv", CI); |
866 | User->replaceUsesOfWith(CI, TheBC); | |
867 | } | |
868 | } | |
869 | ||
870 | Constant *RepValue = NewGV; | |
871 | if (NewGV->getType() != GV->getType()->getElementType()) | |
872 | RepValue = ConstantExpr::getBitCast(RepValue, | |
873 | GV->getType()->getElementType()); | |
874 | ||
875 | // If there is a comparison against null, we will insert a global bool to | |
876 | // keep track of whether the global was initialized yet or not. | |
877 | GlobalVariable *InitBool = | |
878 | new GlobalVariable(Type::getInt1Ty(GV->getContext()), false, | |
879 | GlobalValue::InternalLinkage, | |
880 | ConstantInt::getFalse(GV->getContext()), | |
881 | GV->getName()+".init", GV->getThreadLocalMode()); | |
882 | bool InitBoolUsed = false; | |
883 | ||
884 | // Loop over all uses of GV, processing them in turn. | |
885 | while (!GV->use_empty()) { | |
1a4d82fc | 886 | if (StoreInst *SI = dyn_cast<StoreInst>(GV->user_back())) { |
223e47cc LB |
887 | // The global is initialized when the store to it occurs. |
888 | new StoreInst(ConstantInt::getTrue(GV->getContext()), InitBool, false, 0, | |
889 | SI->getOrdering(), SI->getSynchScope(), SI); | |
890 | SI->eraseFromParent(); | |
891 | continue; | |
892 | } | |
893 | ||
1a4d82fc | 894 | LoadInst *LI = cast<LoadInst>(GV->user_back()); |
223e47cc | 895 | while (!LI->use_empty()) { |
1a4d82fc JJ |
896 | Use &LoadUse = *LI->use_begin(); |
897 | ICmpInst *ICI = dyn_cast<ICmpInst>(LoadUse.getUser()); | |
898 | if (!ICI) { | |
223e47cc LB |
899 | LoadUse = RepValue; |
900 | continue; | |
901 | } | |
902 | ||
223e47cc LB |
903 | // Replace the cmp X, 0 with a use of the bool value. |
904 | // Sink the load to where the compare was, if atomic rules allow us to. | |
905 | Value *LV = new LoadInst(InitBool, InitBool->getName()+".val", false, 0, | |
906 | LI->getOrdering(), LI->getSynchScope(), | |
907 | LI->isUnordered() ? (Instruction*)ICI : LI); | |
908 | InitBoolUsed = true; | |
909 | switch (ICI->getPredicate()) { | |
910 | default: llvm_unreachable("Unknown ICmp Predicate!"); | |
911 | case ICmpInst::ICMP_ULT: | |
912 | case ICmpInst::ICMP_SLT: // X < null -> always false | |
913 | LV = ConstantInt::getFalse(GV->getContext()); | |
914 | break; | |
915 | case ICmpInst::ICMP_ULE: | |
916 | case ICmpInst::ICMP_SLE: | |
917 | case ICmpInst::ICMP_EQ: | |
918 | LV = BinaryOperator::CreateNot(LV, "notinit", ICI); | |
919 | break; | |
920 | case ICmpInst::ICMP_NE: | |
921 | case ICmpInst::ICMP_UGE: | |
922 | case ICmpInst::ICMP_SGE: | |
923 | case ICmpInst::ICMP_UGT: | |
924 | case ICmpInst::ICMP_SGT: | |
925 | break; // no change. | |
926 | } | |
927 | ICI->replaceAllUsesWith(LV); | |
928 | ICI->eraseFromParent(); | |
929 | } | |
930 | LI->eraseFromParent(); | |
931 | } | |
932 | ||
933 | // If the initialization boolean was used, insert it, otherwise delete it. | |
934 | if (!InitBoolUsed) { | |
935 | while (!InitBool->use_empty()) // Delete initializations | |
1a4d82fc | 936 | cast<StoreInst>(InitBool->user_back())->eraseFromParent(); |
223e47cc LB |
937 | delete InitBool; |
938 | } else | |
939 | GV->getParent()->getGlobalList().insert(GV, InitBool); | |
940 | ||
941 | // Now the GV is dead, nuke it and the malloc.. | |
942 | GV->eraseFromParent(); | |
943 | CI->eraseFromParent(); | |
944 | ||
945 | // To further other optimizations, loop over all users of NewGV and try to | |
946 | // constant prop them. This will promote GEP instructions with constant | |
947 | // indices into GEP constant-exprs, which will allow global-opt to hack on it. | |
1a4d82fc | 948 | ConstantPropUsersOf(NewGV, DL, TLI); |
223e47cc | 949 | if (RepValue != NewGV) |
1a4d82fc | 950 | ConstantPropUsersOf(RepValue, DL, TLI); |
223e47cc LB |
951 | |
952 | return NewGV; | |
953 | } | |
954 | ||
955 | /// ValueIsOnlyUsedLocallyOrStoredToOneGlobal - Scan the use-list of V checking | |
956 | /// to make sure that there are no complex uses of V. We permit simple things | |
957 | /// like dereferencing the pointer, but not storing through the address, unless | |
958 | /// it is to the specified global. | |
959 | static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(const Instruction *V, | |
960 | const GlobalVariable *GV, | |
1a4d82fc JJ |
961 | SmallPtrSetImpl<const PHINode*> &PHIs) { |
962 | for (const User *U : V->users()) { | |
963 | const Instruction *Inst = cast<Instruction>(U); | |
223e47cc LB |
964 | |
965 | if (isa<LoadInst>(Inst) || isa<CmpInst>(Inst)) { | |
966 | continue; // Fine, ignore. | |
967 | } | |
968 | ||
969 | if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) { | |
970 | if (SI->getOperand(0) == V && SI->getOperand(1) != GV) | |
971 | return false; // Storing the pointer itself... bad. | |
972 | continue; // Otherwise, storing through it, or storing into GV... fine. | |
973 | } | |
974 | ||
975 | // Must index into the array and into the struct. | |
976 | if (isa<GetElementPtrInst>(Inst) && Inst->getNumOperands() >= 3) { | |
977 | if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs)) | |
978 | return false; | |
979 | continue; | |
980 | } | |
981 | ||
982 | if (const PHINode *PN = dyn_cast<PHINode>(Inst)) { | |
983 | // PHIs are ok if all uses are ok. Don't infinitely recurse through PHI | |
984 | // cycles. | |
85aaf69f | 985 | if (PHIs.insert(PN).second) |
223e47cc LB |
986 | if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(PN, GV, PHIs)) |
987 | return false; | |
988 | continue; | |
989 | } | |
990 | ||
991 | if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Inst)) { | |
992 | if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(BCI, GV, PHIs)) | |
993 | return false; | |
994 | continue; | |
995 | } | |
996 | ||
997 | return false; | |
998 | } | |
999 | return true; | |
1000 | } | |
1001 | ||
1002 | /// ReplaceUsesOfMallocWithGlobal - The Alloc pointer is stored into GV | |
1003 | /// somewhere. Transform all uses of the allocation into loads from the | |
1004 | /// global and uses of the resultant pointer. Further, delete the store into | |
1005 | /// GV. This assumes that these value pass the | |
1006 | /// 'ValueIsOnlyUsedLocallyOrStoredToOneGlobal' predicate. | |
1007 | static void ReplaceUsesOfMallocWithGlobal(Instruction *Alloc, | |
1008 | GlobalVariable *GV) { | |
1009 | while (!Alloc->use_empty()) { | |
1a4d82fc | 1010 | Instruction *U = cast<Instruction>(*Alloc->user_begin()); |
223e47cc LB |
1011 | Instruction *InsertPt = U; |
1012 | if (StoreInst *SI = dyn_cast<StoreInst>(U)) { | |
1013 | // If this is the store of the allocation into the global, remove it. | |
1014 | if (SI->getOperand(1) == GV) { | |
1015 | SI->eraseFromParent(); | |
1016 | continue; | |
1017 | } | |
1018 | } else if (PHINode *PN = dyn_cast<PHINode>(U)) { | |
1019 | // Insert the load in the corresponding predecessor, not right before the | |
1020 | // PHI. | |
1a4d82fc | 1021 | InsertPt = PN->getIncomingBlock(*Alloc->use_begin())->getTerminator(); |
223e47cc LB |
1022 | } else if (isa<BitCastInst>(U)) { |
1023 | // Must be bitcast between the malloc and store to initialize the global. | |
1024 | ReplaceUsesOfMallocWithGlobal(U, GV); | |
1025 | U->eraseFromParent(); | |
1026 | continue; | |
1027 | } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U)) { | |
1028 | // If this is a "GEP bitcast" and the user is a store to the global, then | |
1029 | // just process it as a bitcast. | |
1030 | if (GEPI->hasAllZeroIndices() && GEPI->hasOneUse()) | |
1a4d82fc | 1031 | if (StoreInst *SI = dyn_cast<StoreInst>(GEPI->user_back())) |
223e47cc LB |
1032 | if (SI->getOperand(1) == GV) { |
1033 | // Must be bitcast GEP between the malloc and store to initialize | |
1034 | // the global. | |
1035 | ReplaceUsesOfMallocWithGlobal(GEPI, GV); | |
1036 | GEPI->eraseFromParent(); | |
1037 | continue; | |
1038 | } | |
1039 | } | |
1040 | ||
1041 | // Insert a load from the global, and use it instead of the malloc. | |
1042 | Value *NL = new LoadInst(GV, GV->getName()+".val", InsertPt); | |
1043 | U->replaceUsesOfWith(Alloc, NL); | |
1044 | } | |
1045 | } | |
1046 | ||
1047 | /// LoadUsesSimpleEnoughForHeapSRA - Verify that all uses of V (a load, or a phi | |
1048 | /// of a load) are simple enough to perform heap SRA on. This permits GEP's | |
1049 | /// that index through the array and struct field, icmps of null, and PHIs. | |
1050 | static bool LoadUsesSimpleEnoughForHeapSRA(const Value *V, | |
1a4d82fc JJ |
1051 | SmallPtrSetImpl<const PHINode*> &LoadUsingPHIs, |
1052 | SmallPtrSetImpl<const PHINode*> &LoadUsingPHIsPerLoad) { | |
223e47cc LB |
1053 | // We permit two users of the load: setcc comparing against the null |
1054 | // pointer, and a getelementptr of a specific form. | |
1a4d82fc JJ |
1055 | for (const User *U : V->users()) { |
1056 | const Instruction *UI = cast<Instruction>(U); | |
223e47cc LB |
1057 | |
1058 | // Comparison against null is ok. | |
1a4d82fc | 1059 | if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UI)) { |
223e47cc LB |
1060 | if (!isa<ConstantPointerNull>(ICI->getOperand(1))) |
1061 | return false; | |
1062 | continue; | |
1063 | } | |
1064 | ||
1065 | // getelementptr is also ok, but only a simple form. | |
1a4d82fc | 1066 | if (const GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(UI)) { |
223e47cc LB |
1067 | // Must index into the array and into the struct. |
1068 | if (GEPI->getNumOperands() < 3) | |
1069 | return false; | |
1070 | ||
1071 | // Otherwise the GEP is ok. | |
1072 | continue; | |
1073 | } | |
1074 | ||
1a4d82fc | 1075 | if (const PHINode *PN = dyn_cast<PHINode>(UI)) { |
85aaf69f | 1076 | if (!LoadUsingPHIsPerLoad.insert(PN).second) |
223e47cc LB |
1077 | // This means some phi nodes are dependent on each other. |
1078 | // Avoid infinite looping! | |
1079 | return false; | |
85aaf69f | 1080 | if (!LoadUsingPHIs.insert(PN).second) |
223e47cc LB |
1081 | // If we have already analyzed this PHI, then it is safe. |
1082 | continue; | |
1083 | ||
1084 | // Make sure all uses of the PHI are simple enough to transform. | |
1085 | if (!LoadUsesSimpleEnoughForHeapSRA(PN, | |
1086 | LoadUsingPHIs, LoadUsingPHIsPerLoad)) | |
1087 | return false; | |
1088 | ||
1089 | continue; | |
1090 | } | |
1091 | ||
1092 | // Otherwise we don't know what this is, not ok. | |
1093 | return false; | |
1094 | } | |
1095 | ||
1096 | return true; | |
1097 | } | |
1098 | ||
1099 | ||
1100 | /// AllGlobalLoadUsesSimpleEnoughForHeapSRA - If all users of values loaded from | |
1101 | /// GV are simple enough to perform HeapSRA, return true. | |
1102 | static bool AllGlobalLoadUsesSimpleEnoughForHeapSRA(const GlobalVariable *GV, | |
1103 | Instruction *StoredVal) { | |
1104 | SmallPtrSet<const PHINode*, 32> LoadUsingPHIs; | |
1105 | SmallPtrSet<const PHINode*, 32> LoadUsingPHIsPerLoad; | |
1a4d82fc JJ |
1106 | for (const User *U : GV->users()) |
1107 | if (const LoadInst *LI = dyn_cast<LoadInst>(U)) { | |
223e47cc LB |
1108 | if (!LoadUsesSimpleEnoughForHeapSRA(LI, LoadUsingPHIs, |
1109 | LoadUsingPHIsPerLoad)) | |
1110 | return false; | |
1111 | LoadUsingPHIsPerLoad.clear(); | |
1112 | } | |
1113 | ||
1114 | // If we reach here, we know that all uses of the loads and transitive uses | |
1115 | // (through PHI nodes) are simple enough to transform. However, we don't know | |
1116 | // that all inputs the to the PHI nodes are in the same equivalence sets. | |
1117 | // Check to verify that all operands of the PHIs are either PHIS that can be | |
1118 | // transformed, loads from GV, or MI itself. | |
1a4d82fc | 1119 | for (const PHINode *PN : LoadUsingPHIs) { |
223e47cc LB |
1120 | for (unsigned op = 0, e = PN->getNumIncomingValues(); op != e; ++op) { |
1121 | Value *InVal = PN->getIncomingValue(op); | |
1122 | ||
1123 | // PHI of the stored value itself is ok. | |
1124 | if (InVal == StoredVal) continue; | |
1125 | ||
1126 | if (const PHINode *InPN = dyn_cast<PHINode>(InVal)) { | |
1127 | // One of the PHIs in our set is (optimistically) ok. | |
1128 | if (LoadUsingPHIs.count(InPN)) | |
1129 | continue; | |
1130 | return false; | |
1131 | } | |
1132 | ||
1133 | // Load from GV is ok. | |
1134 | if (const LoadInst *LI = dyn_cast<LoadInst>(InVal)) | |
1135 | if (LI->getOperand(0) == GV) | |
1136 | continue; | |
1137 | ||
1138 | // UNDEF? NULL? | |
1139 | ||
1140 | // Anything else is rejected. | |
1141 | return false; | |
1142 | } | |
1143 | } | |
1144 | ||
1145 | return true; | |
1146 | } | |
1147 | ||
1148 | static Value *GetHeapSROAValue(Value *V, unsigned FieldNo, | |
1149 | DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues, | |
1150 | std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) { | |
1151 | std::vector<Value*> &FieldVals = InsertedScalarizedValues[V]; | |
1152 | ||
1153 | if (FieldNo >= FieldVals.size()) | |
1154 | FieldVals.resize(FieldNo+1); | |
1155 | ||
1156 | // If we already have this value, just reuse the previously scalarized | |
1157 | // version. | |
1158 | if (Value *FieldVal = FieldVals[FieldNo]) | |
1159 | return FieldVal; | |
1160 | ||
1161 | // Depending on what instruction this is, we have several cases. | |
1162 | Value *Result; | |
1163 | if (LoadInst *LI = dyn_cast<LoadInst>(V)) { | |
1164 | // This is a scalarized version of the load from the global. Just create | |
1165 | // a new Load of the scalarized global. | |
1166 | Result = new LoadInst(GetHeapSROAValue(LI->getOperand(0), FieldNo, | |
1167 | InsertedScalarizedValues, | |
1168 | PHIsToRewrite), | |
1169 | LI->getName()+".f"+Twine(FieldNo), LI); | |
1170 | } else if (PHINode *PN = dyn_cast<PHINode>(V)) { | |
1171 | // PN's type is pointer to struct. Make a new PHI of pointer to struct | |
1172 | // field. | |
223e47cc | 1173 | |
1a4d82fc JJ |
1174 | PointerType *PTy = cast<PointerType>(PN->getType()); |
1175 | StructType *ST = cast<StructType>(PTy->getElementType()); | |
1176 | ||
1177 | unsigned AS = PTy->getAddressSpace(); | |
223e47cc | 1178 | PHINode *NewPN = |
1a4d82fc | 1179 | PHINode::Create(PointerType::get(ST->getElementType(FieldNo), AS), |
223e47cc LB |
1180 | PN->getNumIncomingValues(), |
1181 | PN->getName()+".f"+Twine(FieldNo), PN); | |
1182 | Result = NewPN; | |
1183 | PHIsToRewrite.push_back(std::make_pair(PN, FieldNo)); | |
1184 | } else { | |
1185 | llvm_unreachable("Unknown usable value"); | |
1186 | } | |
1187 | ||
1188 | return FieldVals[FieldNo] = Result; | |
1189 | } | |
1190 | ||
1191 | /// RewriteHeapSROALoadUser - Given a load instruction and a value derived from | |
1192 | /// the load, rewrite the derived value to use the HeapSRoA'd load. | |
1193 | static void RewriteHeapSROALoadUser(Instruction *LoadUser, | |
1194 | DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues, | |
1195 | std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) { | |
1196 | // If this is a comparison against null, handle it. | |
1197 | if (ICmpInst *SCI = dyn_cast<ICmpInst>(LoadUser)) { | |
1198 | assert(isa<ConstantPointerNull>(SCI->getOperand(1))); | |
1199 | // If we have a setcc of the loaded pointer, we can use a setcc of any | |
1200 | // field. | |
1201 | Value *NPtr = GetHeapSROAValue(SCI->getOperand(0), 0, | |
1202 | InsertedScalarizedValues, PHIsToRewrite); | |
1203 | ||
1204 | Value *New = new ICmpInst(SCI, SCI->getPredicate(), NPtr, | |
1205 | Constant::getNullValue(NPtr->getType()), | |
1206 | SCI->getName()); | |
1207 | SCI->replaceAllUsesWith(New); | |
1208 | SCI->eraseFromParent(); | |
1209 | return; | |
1210 | } | |
1211 | ||
1212 | // Handle 'getelementptr Ptr, Idx, i32 FieldNo ...' | |
1213 | if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(LoadUser)) { | |
1214 | assert(GEPI->getNumOperands() >= 3 && isa<ConstantInt>(GEPI->getOperand(2)) | |
1215 | && "Unexpected GEPI!"); | |
1216 | ||
1217 | // Load the pointer for this field. | |
1218 | unsigned FieldNo = cast<ConstantInt>(GEPI->getOperand(2))->getZExtValue(); | |
1219 | Value *NewPtr = GetHeapSROAValue(GEPI->getOperand(0), FieldNo, | |
1220 | InsertedScalarizedValues, PHIsToRewrite); | |
1221 | ||
1222 | // Create the new GEP idx vector. | |
1223 | SmallVector<Value*, 8> GEPIdx; | |
1224 | GEPIdx.push_back(GEPI->getOperand(1)); | |
1225 | GEPIdx.append(GEPI->op_begin()+3, GEPI->op_end()); | |
1226 | ||
1227 | Value *NGEPI = GetElementPtrInst::Create(NewPtr, GEPIdx, | |
1228 | GEPI->getName(), GEPI); | |
1229 | GEPI->replaceAllUsesWith(NGEPI); | |
1230 | GEPI->eraseFromParent(); | |
1231 | return; | |
1232 | } | |
1233 | ||
1234 | // Recursively transform the users of PHI nodes. This will lazily create the | |
1235 | // PHIs that are needed for individual elements. Keep track of what PHIs we | |
1236 | // see in InsertedScalarizedValues so that we don't get infinite loops (very | |
1237 | // antisocial). If the PHI is already in InsertedScalarizedValues, it has | |
1238 | // already been seen first by another load, so its uses have already been | |
1239 | // processed. | |
1240 | PHINode *PN = cast<PHINode>(LoadUser); | |
1241 | if (!InsertedScalarizedValues.insert(std::make_pair(PN, | |
1242 | std::vector<Value*>())).second) | |
1243 | return; | |
1244 | ||
1245 | // If this is the first time we've seen this PHI, recursively process all | |
1246 | // users. | |
1a4d82fc | 1247 | for (auto UI = PN->user_begin(), E = PN->user_end(); UI != E;) { |
223e47cc LB |
1248 | Instruction *User = cast<Instruction>(*UI++); |
1249 | RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite); | |
1250 | } | |
1251 | } | |
1252 | ||
1253 | /// RewriteUsesOfLoadForHeapSRoA - We are performing Heap SRoA on a global. Ptr | |
1254 | /// is a value loaded from the global. Eliminate all uses of Ptr, making them | |
1255 | /// use FieldGlobals instead. All uses of loaded values satisfy | |
1256 | /// AllGlobalLoadUsesSimpleEnoughForHeapSRA. | |
1257 | static void RewriteUsesOfLoadForHeapSRoA(LoadInst *Load, | |
1258 | DenseMap<Value*, std::vector<Value*> > &InsertedScalarizedValues, | |
1259 | std::vector<std::pair<PHINode*, unsigned> > &PHIsToRewrite) { | |
1a4d82fc | 1260 | for (auto UI = Load->user_begin(), E = Load->user_end(); UI != E;) { |
223e47cc LB |
1261 | Instruction *User = cast<Instruction>(*UI++); |
1262 | RewriteHeapSROALoadUser(User, InsertedScalarizedValues, PHIsToRewrite); | |
1263 | } | |
1264 | ||
1265 | if (Load->use_empty()) { | |
1266 | Load->eraseFromParent(); | |
1267 | InsertedScalarizedValues.erase(Load); | |
1268 | } | |
1269 | } | |
1270 | ||
1271 | /// PerformHeapAllocSRoA - CI is an allocation of an array of structures. Break | |
1272 | /// it up into multiple allocations of arrays of the fields. | |
1273 | static GlobalVariable *PerformHeapAllocSRoA(GlobalVariable *GV, CallInst *CI, | |
1a4d82fc | 1274 | Value *NElems, const DataLayout *DL, |
223e47cc LB |
1275 | const TargetLibraryInfo *TLI) { |
1276 | DEBUG(dbgs() << "SROA HEAP ALLOC: " << *GV << " MALLOC = " << *CI << '\n'); | |
1277 | Type *MAT = getMallocAllocatedType(CI, TLI); | |
1278 | StructType *STy = cast<StructType>(MAT); | |
1279 | ||
1280 | // There is guaranteed to be at least one use of the malloc (storing | |
1281 | // it into GV). If there are other uses, change them to be uses of | |
1282 | // the global to simplify later code. This also deletes the store | |
1283 | // into GV. | |
1284 | ReplaceUsesOfMallocWithGlobal(CI, GV); | |
1285 | ||
1286 | // Okay, at this point, there are no users of the malloc. Insert N | |
1287 | // new mallocs at the same place as CI, and N globals. | |
1288 | std::vector<Value*> FieldGlobals; | |
1289 | std::vector<Value*> FieldMallocs; | |
1290 | ||
1a4d82fc | 1291 | unsigned AS = GV->getType()->getPointerAddressSpace(); |
223e47cc LB |
1292 | for (unsigned FieldNo = 0, e = STy->getNumElements(); FieldNo != e;++FieldNo){ |
1293 | Type *FieldTy = STy->getElementType(FieldNo); | |
1a4d82fc | 1294 | PointerType *PFieldTy = PointerType::get(FieldTy, AS); |
223e47cc LB |
1295 | |
1296 | GlobalVariable *NGV = | |
1297 | new GlobalVariable(*GV->getParent(), | |
1298 | PFieldTy, false, GlobalValue::InternalLinkage, | |
1299 | Constant::getNullValue(PFieldTy), | |
1300 | GV->getName() + ".f" + Twine(FieldNo), GV, | |
1301 | GV->getThreadLocalMode()); | |
1302 | FieldGlobals.push_back(NGV); | |
1303 | ||
1a4d82fc | 1304 | unsigned TypeSize = DL->getTypeAllocSize(FieldTy); |
223e47cc | 1305 | if (StructType *ST = dyn_cast<StructType>(FieldTy)) |
1a4d82fc JJ |
1306 | TypeSize = DL->getStructLayout(ST)->getSizeInBytes(); |
1307 | Type *IntPtrTy = DL->getIntPtrType(CI->getType()); | |
223e47cc LB |
1308 | Value *NMI = CallInst::CreateMalloc(CI, IntPtrTy, FieldTy, |
1309 | ConstantInt::get(IntPtrTy, TypeSize), | |
1a4d82fc | 1310 | NElems, nullptr, |
223e47cc LB |
1311 | CI->getName() + ".f" + Twine(FieldNo)); |
1312 | FieldMallocs.push_back(NMI); | |
1313 | new StoreInst(NMI, NGV, CI); | |
1314 | } | |
1315 | ||
1316 | // The tricky aspect of this transformation is handling the case when malloc | |
1317 | // fails. In the original code, malloc failing would set the result pointer | |
1318 | // of malloc to null. In this case, some mallocs could succeed and others | |
1319 | // could fail. As such, we emit code that looks like this: | |
1320 | // F0 = malloc(field0) | |
1321 | // F1 = malloc(field1) | |
1322 | // F2 = malloc(field2) | |
1323 | // if (F0 == 0 || F1 == 0 || F2 == 0) { | |
1324 | // if (F0) { free(F0); F0 = 0; } | |
1325 | // if (F1) { free(F1); F1 = 0; } | |
1326 | // if (F2) { free(F2); F2 = 0; } | |
1327 | // } | |
1328 | // The malloc can also fail if its argument is too large. | |
1329 | Constant *ConstantZero = ConstantInt::get(CI->getArgOperand(0)->getType(), 0); | |
1330 | Value *RunningOr = new ICmpInst(CI, ICmpInst::ICMP_SLT, CI->getArgOperand(0), | |
1331 | ConstantZero, "isneg"); | |
1332 | for (unsigned i = 0, e = FieldMallocs.size(); i != e; ++i) { | |
1333 | Value *Cond = new ICmpInst(CI, ICmpInst::ICMP_EQ, FieldMallocs[i], | |
1334 | Constant::getNullValue(FieldMallocs[i]->getType()), | |
1335 | "isnull"); | |
1336 | RunningOr = BinaryOperator::CreateOr(RunningOr, Cond, "tmp", CI); | |
1337 | } | |
1338 | ||
1339 | // Split the basic block at the old malloc. | |
1340 | BasicBlock *OrigBB = CI->getParent(); | |
1341 | BasicBlock *ContBB = OrigBB->splitBasicBlock(CI, "malloc_cont"); | |
1342 | ||
1343 | // Create the block to check the first condition. Put all these blocks at the | |
1344 | // end of the function as they are unlikely to be executed. | |
1345 | BasicBlock *NullPtrBlock = BasicBlock::Create(OrigBB->getContext(), | |
1346 | "malloc_ret_null", | |
1347 | OrigBB->getParent()); | |
1348 | ||
1349 | // Remove the uncond branch from OrigBB to ContBB, turning it into a cond | |
1350 | // branch on RunningOr. | |
1351 | OrigBB->getTerminator()->eraseFromParent(); | |
1352 | BranchInst::Create(NullPtrBlock, ContBB, RunningOr, OrigBB); | |
1353 | ||
1354 | // Within the NullPtrBlock, we need to emit a comparison and branch for each | |
1355 | // pointer, because some may be null while others are not. | |
1356 | for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) { | |
1357 | Value *GVVal = new LoadInst(FieldGlobals[i], "tmp", NullPtrBlock); | |
1358 | Value *Cmp = new ICmpInst(*NullPtrBlock, ICmpInst::ICMP_NE, GVVal, | |
1359 | Constant::getNullValue(GVVal->getType())); | |
1360 | BasicBlock *FreeBlock = BasicBlock::Create(Cmp->getContext(), "free_it", | |
1361 | OrigBB->getParent()); | |
1362 | BasicBlock *NextBlock = BasicBlock::Create(Cmp->getContext(), "next", | |
1363 | OrigBB->getParent()); | |
1364 | Instruction *BI = BranchInst::Create(FreeBlock, NextBlock, | |
1365 | Cmp, NullPtrBlock); | |
1366 | ||
1367 | // Fill in FreeBlock. | |
1368 | CallInst::CreateFree(GVVal, BI); | |
1369 | new StoreInst(Constant::getNullValue(GVVal->getType()), FieldGlobals[i], | |
1370 | FreeBlock); | |
1371 | BranchInst::Create(NextBlock, FreeBlock); | |
1372 | ||
1373 | NullPtrBlock = NextBlock; | |
1374 | } | |
1375 | ||
1376 | BranchInst::Create(ContBB, NullPtrBlock); | |
1377 | ||
1378 | // CI is no longer needed, remove it. | |
1379 | CI->eraseFromParent(); | |
1380 | ||
1381 | /// InsertedScalarizedLoads - As we process loads, if we can't immediately | |
1382 | /// update all uses of the load, keep track of what scalarized loads are | |
1383 | /// inserted for a given load. | |
1384 | DenseMap<Value*, std::vector<Value*> > InsertedScalarizedValues; | |
1385 | InsertedScalarizedValues[GV] = FieldGlobals; | |
1386 | ||
1387 | std::vector<std::pair<PHINode*, unsigned> > PHIsToRewrite; | |
1388 | ||
1389 | // Okay, the malloc site is completely handled. All of the uses of GV are now | |
1390 | // loads, and all uses of those loads are simple. Rewrite them to use loads | |
1391 | // of the per-field globals instead. | |
1a4d82fc | 1392 | for (auto UI = GV->user_begin(), E = GV->user_end(); UI != E;) { |
223e47cc LB |
1393 | Instruction *User = cast<Instruction>(*UI++); |
1394 | ||
1395 | if (LoadInst *LI = dyn_cast<LoadInst>(User)) { | |
1396 | RewriteUsesOfLoadForHeapSRoA(LI, InsertedScalarizedValues, PHIsToRewrite); | |
1397 | continue; | |
1398 | } | |
1399 | ||
1400 | // Must be a store of null. | |
1401 | StoreInst *SI = cast<StoreInst>(User); | |
1402 | assert(isa<ConstantPointerNull>(SI->getOperand(0)) && | |
1403 | "Unexpected heap-sra user!"); | |
1404 | ||
1405 | // Insert a store of null into each global. | |
1406 | for (unsigned i = 0, e = FieldGlobals.size(); i != e; ++i) { | |
1407 | PointerType *PT = cast<PointerType>(FieldGlobals[i]->getType()); | |
1408 | Constant *Null = Constant::getNullValue(PT->getElementType()); | |
1409 | new StoreInst(Null, FieldGlobals[i], SI); | |
1410 | } | |
1411 | // Erase the original store. | |
1412 | SI->eraseFromParent(); | |
1413 | } | |
1414 | ||
1415 | // While we have PHIs that are interesting to rewrite, do it. | |
1416 | while (!PHIsToRewrite.empty()) { | |
1417 | PHINode *PN = PHIsToRewrite.back().first; | |
1418 | unsigned FieldNo = PHIsToRewrite.back().second; | |
1419 | PHIsToRewrite.pop_back(); | |
1420 | PHINode *FieldPN = cast<PHINode>(InsertedScalarizedValues[PN][FieldNo]); | |
1421 | assert(FieldPN->getNumIncomingValues() == 0 &&"Already processed this phi"); | |
1422 | ||
1423 | // Add all the incoming values. This can materialize more phis. | |
1424 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |
1425 | Value *InVal = PN->getIncomingValue(i); | |
1426 | InVal = GetHeapSROAValue(InVal, FieldNo, InsertedScalarizedValues, | |
1427 | PHIsToRewrite); | |
1428 | FieldPN->addIncoming(InVal, PN->getIncomingBlock(i)); | |
1429 | } | |
1430 | } | |
1431 | ||
1432 | // Drop all inter-phi links and any loads that made it this far. | |
1433 | for (DenseMap<Value*, std::vector<Value*> >::iterator | |
1434 | I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end(); | |
1435 | I != E; ++I) { | |
1436 | if (PHINode *PN = dyn_cast<PHINode>(I->first)) | |
1437 | PN->dropAllReferences(); | |
1438 | else if (LoadInst *LI = dyn_cast<LoadInst>(I->first)) | |
1439 | LI->dropAllReferences(); | |
1440 | } | |
1441 | ||
1442 | // Delete all the phis and loads now that inter-references are dead. | |
1443 | for (DenseMap<Value*, std::vector<Value*> >::iterator | |
1444 | I = InsertedScalarizedValues.begin(), E = InsertedScalarizedValues.end(); | |
1445 | I != E; ++I) { | |
1446 | if (PHINode *PN = dyn_cast<PHINode>(I->first)) | |
1447 | PN->eraseFromParent(); | |
1448 | else if (LoadInst *LI = dyn_cast<LoadInst>(I->first)) | |
1449 | LI->eraseFromParent(); | |
1450 | } | |
1451 | ||
1452 | // The old global is now dead, remove it. | |
1453 | GV->eraseFromParent(); | |
1454 | ||
1455 | ++NumHeapSRA; | |
1456 | return cast<GlobalVariable>(FieldGlobals[0]); | |
1457 | } | |
1458 | ||
1459 | /// TryToOptimizeStoreOfMallocToGlobal - This function is called when we see a | |
1460 | /// pointer global variable with a single value stored it that is a malloc or | |
1461 | /// cast of malloc. | |
1462 | static bool TryToOptimizeStoreOfMallocToGlobal(GlobalVariable *GV, | |
1463 | CallInst *CI, | |
1464 | Type *AllocTy, | |
1465 | AtomicOrdering Ordering, | |
1466 | Module::global_iterator &GVI, | |
1a4d82fc | 1467 | const DataLayout *DL, |
223e47cc | 1468 | TargetLibraryInfo *TLI) { |
1a4d82fc | 1469 | if (!DL) |
223e47cc LB |
1470 | return false; |
1471 | ||
1472 | // If this is a malloc of an abstract type, don't touch it. | |
1473 | if (!AllocTy->isSized()) | |
1474 | return false; | |
1475 | ||
1476 | // We can't optimize this global unless all uses of it are *known* to be | |
1477 | // of the malloc value, not of the null initializer value (consider a use | |
1478 | // that compares the global's value against zero to see if the malloc has | |
1479 | // been reached). To do this, we check to see if all uses of the global | |
1480 | // would trap if the global were null: this proves that they must all | |
1481 | // happen after the malloc. | |
1482 | if (!AllUsesOfLoadedValueWillTrapIfNull(GV)) | |
1483 | return false; | |
1484 | ||
1485 | // We can't optimize this if the malloc itself is used in a complex way, | |
1486 | // for example, being stored into multiple globals. This allows the | |
1487 | // malloc to be stored into the specified global, loaded icmp'd, and | |
1488 | // GEP'd. These are all things we could transform to using the global | |
1489 | // for. | |
1490 | SmallPtrSet<const PHINode*, 8> PHIs; | |
1491 | if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(CI, GV, PHIs)) | |
1492 | return false; | |
1493 | ||
1494 | // If we have a global that is only initialized with a fixed size malloc, | |
1495 | // transform the program to use global memory instead of malloc'd memory. | |
1496 | // This eliminates dynamic allocation, avoids an indirection accessing the | |
1497 | // data, and exposes the resultant global to further GlobalOpt. | |
1498 | // We cannot optimize the malloc if we cannot determine malloc array size. | |
1a4d82fc | 1499 | Value *NElems = getMallocArraySize(CI, DL, TLI, true); |
223e47cc LB |
1500 | if (!NElems) |
1501 | return false; | |
1502 | ||
1503 | if (ConstantInt *NElements = dyn_cast<ConstantInt>(NElems)) | |
1504 | // Restrict this transformation to only working on small allocations | |
1505 | // (2048 bytes currently), as we don't want to introduce a 16M global or | |
1506 | // something. | |
1a4d82fc JJ |
1507 | if (NElements->getZExtValue() * DL->getTypeAllocSize(AllocTy) < 2048) { |
1508 | GVI = OptimizeGlobalAddressOfMalloc(GV, CI, AllocTy, NElements, DL, TLI); | |
223e47cc LB |
1509 | return true; |
1510 | } | |
1511 | ||
1512 | // If the allocation is an array of structures, consider transforming this | |
1513 | // into multiple malloc'd arrays, one for each field. This is basically | |
1514 | // SRoA for malloc'd memory. | |
1515 | ||
1516 | if (Ordering != NotAtomic) | |
1517 | return false; | |
1518 | ||
1519 | // If this is an allocation of a fixed size array of structs, analyze as a | |
1520 | // variable size array. malloc [100 x struct],1 -> malloc struct, 100 | |
1521 | if (NElems == ConstantInt::get(CI->getArgOperand(0)->getType(), 1)) | |
1522 | if (ArrayType *AT = dyn_cast<ArrayType>(AllocTy)) | |
1523 | AllocTy = AT->getElementType(); | |
1524 | ||
1525 | StructType *AllocSTy = dyn_cast<StructType>(AllocTy); | |
1526 | if (!AllocSTy) | |
1527 | return false; | |
1528 | ||
1529 | // This the structure has an unreasonable number of fields, leave it | |
1530 | // alone. | |
1531 | if (AllocSTy->getNumElements() <= 16 && AllocSTy->getNumElements() != 0 && | |
1532 | AllGlobalLoadUsesSimpleEnoughForHeapSRA(GV, CI)) { | |
1533 | ||
1534 | // If this is a fixed size array, transform the Malloc to be an alloc of | |
1535 | // structs. malloc [100 x struct],1 -> malloc struct, 100 | |
1536 | if (ArrayType *AT = dyn_cast<ArrayType>(getMallocAllocatedType(CI, TLI))) { | |
1a4d82fc JJ |
1537 | Type *IntPtrTy = DL->getIntPtrType(CI->getType()); |
1538 | unsigned TypeSize = DL->getStructLayout(AllocSTy)->getSizeInBytes(); | |
223e47cc LB |
1539 | Value *AllocSize = ConstantInt::get(IntPtrTy, TypeSize); |
1540 | Value *NumElements = ConstantInt::get(IntPtrTy, AT->getNumElements()); | |
1541 | Instruction *Malloc = CallInst::CreateMalloc(CI, IntPtrTy, AllocSTy, | |
1542 | AllocSize, NumElements, | |
1a4d82fc | 1543 | nullptr, CI->getName()); |
223e47cc LB |
1544 | Instruction *Cast = new BitCastInst(Malloc, CI->getType(), "tmp", CI); |
1545 | CI->replaceAllUsesWith(Cast); | |
1546 | CI->eraseFromParent(); | |
1547 | if (BitCastInst *BCI = dyn_cast<BitCastInst>(Malloc)) | |
1548 | CI = cast<CallInst>(BCI->getOperand(0)); | |
1549 | else | |
1550 | CI = cast<CallInst>(Malloc); | |
1551 | } | |
1552 | ||
1a4d82fc JJ |
1553 | GVI = PerformHeapAllocSRoA(GV, CI, getMallocArraySize(CI, DL, TLI, true), |
1554 | DL, TLI); | |
223e47cc LB |
1555 | return true; |
1556 | } | |
1557 | ||
1558 | return false; | |
1559 | } | |
1560 | ||
1561 | // OptimizeOnceStoredGlobal - Try to optimize globals based on the knowledge | |
1562 | // that only one value (besides its initializer) is ever stored to the global. | |
1563 | static bool OptimizeOnceStoredGlobal(GlobalVariable *GV, Value *StoredOnceVal, | |
1564 | AtomicOrdering Ordering, | |
1565 | Module::global_iterator &GVI, | |
1a4d82fc JJ |
1566 | const DataLayout *DL, |
1567 | TargetLibraryInfo *TLI) { | |
223e47cc LB |
1568 | // Ignore no-op GEPs and bitcasts. |
1569 | StoredOnceVal = StoredOnceVal->stripPointerCasts(); | |
1570 | ||
1571 | // If we are dealing with a pointer global that is initialized to null and | |
1572 | // only has one (non-null) value stored into it, then we can optimize any | |
1573 | // users of the loaded value (often calls and loads) that would trap if the | |
1574 | // value was null. | |
1575 | if (GV->getInitializer()->getType()->isPointerTy() && | |
1576 | GV->getInitializer()->isNullValue()) { | |
1577 | if (Constant *SOVC = dyn_cast<Constant>(StoredOnceVal)) { | |
1578 | if (GV->getInitializer()->getType() != SOVC->getType()) | |
1579 | SOVC = ConstantExpr::getBitCast(SOVC, GV->getInitializer()->getType()); | |
1580 | ||
1581 | // Optimize away any trapping uses of the loaded value. | |
1a4d82fc | 1582 | if (OptimizeAwayTrappingUsesOfLoads(GV, SOVC, DL, TLI)) |
223e47cc LB |
1583 | return true; |
1584 | } else if (CallInst *CI = extractMallocCall(StoredOnceVal, TLI)) { | |
1585 | Type *MallocType = getMallocAllocatedType(CI, TLI); | |
1586 | if (MallocType && | |
1587 | TryToOptimizeStoreOfMallocToGlobal(GV, CI, MallocType, Ordering, GVI, | |
1a4d82fc | 1588 | DL, TLI)) |
223e47cc LB |
1589 | return true; |
1590 | } | |
1591 | } | |
1592 | ||
1593 | return false; | |
1594 | } | |
1595 | ||
1596 | /// TryToShrinkGlobalToBoolean - At this point, we have learned that the only | |
1597 | /// two values ever stored into GV are its initializer and OtherVal. See if we | |
1598 | /// can shrink the global into a boolean and select between the two values | |
1599 | /// whenever it is used. This exposes the values to other scalar optimizations. | |
1600 | static bool TryToShrinkGlobalToBoolean(GlobalVariable *GV, Constant *OtherVal) { | |
1601 | Type *GVElType = GV->getType()->getElementType(); | |
1602 | ||
1603 | // If GVElType is already i1, it is already shrunk. If the type of the GV is | |
1604 | // an FP value, pointer or vector, don't do this optimization because a select | |
1605 | // between them is very expensive and unlikely to lead to later | |
1606 | // simplification. In these cases, we typically end up with "cond ? v1 : v2" | |
1607 | // where v1 and v2 both require constant pool loads, a big loss. | |
1608 | if (GVElType == Type::getInt1Ty(GV->getContext()) || | |
1609 | GVElType->isFloatingPointTy() || | |
1610 | GVElType->isPointerTy() || GVElType->isVectorTy()) | |
1611 | return false; | |
1612 | ||
1613 | // Walk the use list of the global seeing if all the uses are load or store. | |
1614 | // If there is anything else, bail out. | |
1a4d82fc | 1615 | for (User *U : GV->users()) |
223e47cc LB |
1616 | if (!isa<LoadInst>(U) && !isa<StoreInst>(U)) |
1617 | return false; | |
223e47cc LB |
1618 | |
1619 | DEBUG(dbgs() << " *** SHRINKING TO BOOL: " << *GV); | |
1620 | ||
1621 | // Create the new global, initializing it to false. | |
1622 | GlobalVariable *NewGV = new GlobalVariable(Type::getInt1Ty(GV->getContext()), | |
1623 | false, | |
1624 | GlobalValue::InternalLinkage, | |
1625 | ConstantInt::getFalse(GV->getContext()), | |
1626 | GV->getName()+".b", | |
970d7e83 LB |
1627 | GV->getThreadLocalMode(), |
1628 | GV->getType()->getAddressSpace()); | |
223e47cc LB |
1629 | GV->getParent()->getGlobalList().insert(GV, NewGV); |
1630 | ||
1631 | Constant *InitVal = GV->getInitializer(); | |
1632 | assert(InitVal->getType() != Type::getInt1Ty(GV->getContext()) && | |
1633 | "No reason to shrink to bool!"); | |
1634 | ||
1635 | // If initialized to zero and storing one into the global, we can use a cast | |
1636 | // instead of a select to synthesize the desired value. | |
1637 | bool IsOneZero = false; | |
1638 | if (ConstantInt *CI = dyn_cast<ConstantInt>(OtherVal)) | |
1639 | IsOneZero = InitVal->isNullValue() && CI->isOne(); | |
1640 | ||
1641 | while (!GV->use_empty()) { | |
1a4d82fc | 1642 | Instruction *UI = cast<Instruction>(GV->user_back()); |
223e47cc LB |
1643 | if (StoreInst *SI = dyn_cast<StoreInst>(UI)) { |
1644 | // Change the store into a boolean store. | |
1645 | bool StoringOther = SI->getOperand(0) == OtherVal; | |
1646 | // Only do this if we weren't storing a loaded value. | |
1647 | Value *StoreVal; | |
970d7e83 | 1648 | if (StoringOther || SI->getOperand(0) == InitVal) { |
223e47cc LB |
1649 | StoreVal = ConstantInt::get(Type::getInt1Ty(GV->getContext()), |
1650 | StoringOther); | |
970d7e83 | 1651 | } else { |
223e47cc LB |
1652 | // Otherwise, we are storing a previously loaded copy. To do this, |
1653 | // change the copy from copying the original value to just copying the | |
1654 | // bool. | |
1655 | Instruction *StoredVal = cast<Instruction>(SI->getOperand(0)); | |
1656 | ||
1657 | // If we've already replaced the input, StoredVal will be a cast or | |
1658 | // select instruction. If not, it will be a load of the original | |
1659 | // global. | |
1660 | if (LoadInst *LI = dyn_cast<LoadInst>(StoredVal)) { | |
1661 | assert(LI->getOperand(0) == GV && "Not a copy!"); | |
1662 | // Insert a new load, to preserve the saved value. | |
1663 | StoreVal = new LoadInst(NewGV, LI->getName()+".b", false, 0, | |
1664 | LI->getOrdering(), LI->getSynchScope(), LI); | |
1665 | } else { | |
1666 | assert((isa<CastInst>(StoredVal) || isa<SelectInst>(StoredVal)) && | |
1667 | "This is not a form that we understand!"); | |
1668 | StoreVal = StoredVal->getOperand(0); | |
1669 | assert(isa<LoadInst>(StoreVal) && "Not a load of NewGV!"); | |
1670 | } | |
1671 | } | |
1672 | new StoreInst(StoreVal, NewGV, false, 0, | |
1673 | SI->getOrdering(), SI->getSynchScope(), SI); | |
1674 | } else { | |
1675 | // Change the load into a load of bool then a select. | |
1676 | LoadInst *LI = cast<LoadInst>(UI); | |
1677 | LoadInst *NLI = new LoadInst(NewGV, LI->getName()+".b", false, 0, | |
1678 | LI->getOrdering(), LI->getSynchScope(), LI); | |
1679 | Value *NSI; | |
1680 | if (IsOneZero) | |
1681 | NSI = new ZExtInst(NLI, LI->getType(), "", LI); | |
1682 | else | |
1683 | NSI = SelectInst::Create(NLI, OtherVal, InitVal, "", LI); | |
1684 | NSI->takeName(LI); | |
1685 | LI->replaceAllUsesWith(NSI); | |
1686 | } | |
1687 | UI->eraseFromParent(); | |
1688 | } | |
1689 | ||
970d7e83 LB |
1690 | // Retain the name of the old global variable. People who are debugging their |
1691 | // programs may expect these variables to be named the same. | |
1692 | NewGV->takeName(GV); | |
223e47cc LB |
1693 | GV->eraseFromParent(); |
1694 | return true; | |
1695 | } | |
1696 | ||
1697 | ||
1698 | /// ProcessGlobal - Analyze the specified global variable and optimize it if | |
1699 | /// possible. If we make a change, return true. | |
1700 | bool GlobalOpt::ProcessGlobal(GlobalVariable *GV, | |
1701 | Module::global_iterator &GVI) { | |
223e47cc LB |
1702 | // Do more involved optimizations if the global is internal. |
1703 | GV->removeDeadConstantUsers(); | |
1704 | ||
1705 | if (GV->use_empty()) { | |
1706 | DEBUG(dbgs() << "GLOBAL DEAD: " << *GV); | |
1707 | GV->eraseFromParent(); | |
1708 | ++NumDeleted; | |
1709 | return true; | |
1710 | } | |
1711 | ||
1712 | if (!GV->hasLocalLinkage()) | |
1713 | return false; | |
1714 | ||
223e47cc LB |
1715 | GlobalStatus GS; |
1716 | ||
1a4d82fc | 1717 | if (GlobalStatus::analyzeGlobal(GV, GS)) |
223e47cc LB |
1718 | return false; |
1719 | ||
1a4d82fc | 1720 | if (!GS.IsCompared && !GV->hasUnnamedAddr()) { |
223e47cc LB |
1721 | GV->setUnnamedAddr(true); |
1722 | NumUnnamed++; | |
1723 | } | |
1724 | ||
1725 | if (GV->isConstant() || !GV->hasInitializer()) | |
1726 | return false; | |
1727 | ||
1a4d82fc | 1728 | return ProcessInternalGlobal(GV, GVI, GS); |
223e47cc LB |
1729 | } |
1730 | ||
1731 | /// ProcessInternalGlobal - Analyze the specified global variable and optimize | |
1732 | /// it if possible. If we make a change, return true. | |
1733 | bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV, | |
1734 | Module::global_iterator &GVI, | |
223e47cc LB |
1735 | const GlobalStatus &GS) { |
1736 | // If this is a first class global and has only one accessing function | |
1a4d82fc JJ |
1737 | // and this function is main (which we know is not recursive), we replace |
1738 | // the global with a local alloca in this function. | |
223e47cc | 1739 | // |
1a4d82fc | 1740 | // NOTE: It doesn't make sense to promote non-single-value types since we |
223e47cc LB |
1741 | // are just replacing static memory to stack memory. |
1742 | // | |
1743 | // If the global is in different address space, don't bring it to stack. | |
1744 | if (!GS.HasMultipleAccessingFunctions && | |
1745 | GS.AccessingFunction && !GS.HasNonInstructionUser && | |
1746 | GV->getType()->getElementType()->isSingleValueType() && | |
1747 | GS.AccessingFunction->getName() == "main" && | |
1748 | GS.AccessingFunction->hasExternalLinkage() && | |
1749 | GV->getType()->getAddressSpace() == 0) { | |
1750 | DEBUG(dbgs() << "LOCALIZING GLOBAL: " << *GV); | |
1751 | Instruction &FirstI = const_cast<Instruction&>(*GS.AccessingFunction | |
1752 | ->getEntryBlock().begin()); | |
1753 | Type *ElemTy = GV->getType()->getElementType(); | |
1754 | // FIXME: Pass Global's alignment when globals have alignment | |
1a4d82fc JJ |
1755 | AllocaInst *Alloca = new AllocaInst(ElemTy, nullptr, |
1756 | GV->getName(), &FirstI); | |
223e47cc LB |
1757 | if (!isa<UndefValue>(GV->getInitializer())) |
1758 | new StoreInst(GV->getInitializer(), Alloca, &FirstI); | |
1759 | ||
1760 | GV->replaceAllUsesWith(Alloca); | |
1761 | GV->eraseFromParent(); | |
1762 | ++NumLocalized; | |
1763 | return true; | |
1764 | } | |
1765 | ||
1766 | // If the global is never loaded (but may be stored to), it is dead. | |
1767 | // Delete it now. | |
1a4d82fc | 1768 | if (!GS.IsLoaded) { |
223e47cc LB |
1769 | DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV); |
1770 | ||
1771 | bool Changed; | |
1772 | if (isLeakCheckerRoot(GV)) { | |
1773 | // Delete any constant stores to the global. | |
1774 | Changed = CleanupPointerRootUsers(GV, TLI); | |
1775 | } else { | |
1776 | // Delete any stores we can find to the global. We may not be able to | |
1777 | // make it completely dead though. | |
1a4d82fc | 1778 | Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, TLI); |
223e47cc LB |
1779 | } |
1780 | ||
1781 | // If the global is dead now, delete it. | |
1782 | if (GV->use_empty()) { | |
1783 | GV->eraseFromParent(); | |
1784 | ++NumDeleted; | |
1785 | Changed = true; | |
1786 | } | |
1787 | return Changed; | |
1788 | ||
1a4d82fc | 1789 | } else if (GS.StoredType <= GlobalStatus::InitializerStored) { |
970d7e83 | 1790 | DEBUG(dbgs() << "MARKING CONSTANT: " << *GV << "\n"); |
223e47cc LB |
1791 | GV->setConstant(true); |
1792 | ||
1793 | // Clean up any obviously simplifiable users now. | |
1a4d82fc | 1794 | CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, TLI); |
223e47cc LB |
1795 | |
1796 | // If the global is dead now, just nuke it. | |
1797 | if (GV->use_empty()) { | |
1798 | DEBUG(dbgs() << " *** Marking constant allowed us to simplify " | |
1799 | << "all users and delete global!\n"); | |
1800 | GV->eraseFromParent(); | |
1801 | ++NumDeleted; | |
1802 | } | |
1803 | ||
1804 | ++NumMarked; | |
1805 | return true; | |
1806 | } else if (!GV->getInitializer()->getType()->isSingleValueType()) { | |
1a4d82fc JJ |
1807 | if (DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>()) { |
1808 | const DataLayout &DL = DLP->getDataLayout(); | |
1809 | if (GlobalVariable *FirstNewGV = SRAGlobal(GV, DL)) { | |
223e47cc LB |
1810 | GVI = FirstNewGV; // Don't skip the newly produced globals! |
1811 | return true; | |
1812 | } | |
1a4d82fc JJ |
1813 | } |
1814 | } else if (GS.StoredType == GlobalStatus::StoredOnce) { | |
223e47cc LB |
1815 | // If the initial value for the global was an undef value, and if only |
1816 | // one other value was stored into it, we can just change the | |
1817 | // initializer to be the stored value, then delete all stores to the | |
1818 | // global. This allows us to mark it constant. | |
1819 | if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) | |
1820 | if (isa<UndefValue>(GV->getInitializer())) { | |
1821 | // Change the initial value here. | |
1822 | GV->setInitializer(SOVConstant); | |
1823 | ||
1824 | // Clean up any obviously simplifiable users now. | |
1a4d82fc | 1825 | CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, TLI); |
223e47cc LB |
1826 | |
1827 | if (GV->use_empty()) { | |
1828 | DEBUG(dbgs() << " *** Substituting initializer allowed us to " | |
1829 | << "simplify all users and delete global!\n"); | |
1830 | GV->eraseFromParent(); | |
1831 | ++NumDeleted; | |
1832 | } else { | |
1833 | GVI = GV; | |
1834 | } | |
1835 | ++NumSubstitute; | |
1836 | return true; | |
1837 | } | |
1838 | ||
1839 | // Try to optimize globals based on the knowledge that only one value | |
1840 | // (besides its initializer) is ever stored to the global. | |
1841 | if (OptimizeOnceStoredGlobal(GV, GS.StoredOnceValue, GS.Ordering, GVI, | |
1a4d82fc | 1842 | DL, TLI)) |
223e47cc LB |
1843 | return true; |
1844 | ||
1845 | // Otherwise, if the global was not a boolean, we can shrink it to be a | |
1846 | // boolean. | |
1a4d82fc JJ |
1847 | if (Constant *SOVConstant = dyn_cast<Constant>(GS.StoredOnceValue)) { |
1848 | if (GS.Ordering == NotAtomic) { | |
1849 | if (TryToShrinkGlobalToBoolean(GV, SOVConstant)) { | |
1850 | ++NumShrunkToBool; | |
1851 | return true; | |
1852 | } | |
223e47cc | 1853 | } |
1a4d82fc | 1854 | } |
223e47cc LB |
1855 | } |
1856 | ||
1857 | return false; | |
1858 | } | |
1859 | ||
1860 | /// ChangeCalleesToFastCall - Walk all of the direct calls of the specified | |
1861 | /// function, changing them to FastCC. | |
1862 | static void ChangeCalleesToFastCall(Function *F) { | |
1a4d82fc JJ |
1863 | for (User *U : F->users()) { |
1864 | if (isa<BlockAddress>(U)) | |
223e47cc | 1865 | continue; |
1a4d82fc JJ |
1866 | CallSite CS(cast<Instruction>(U)); |
1867 | CS.setCallingConv(CallingConv::Fast); | |
223e47cc LB |
1868 | } |
1869 | } | |
1870 | ||
970d7e83 | 1871 | static AttributeSet StripNest(LLVMContext &C, const AttributeSet &Attrs) { |
223e47cc | 1872 | for (unsigned i = 0, e = Attrs.getNumSlots(); i != e; ++i) { |
970d7e83 LB |
1873 | unsigned Index = Attrs.getSlotIndex(i); |
1874 | if (!Attrs.getSlotAttributes(i).hasAttribute(Index, Attribute::Nest)) | |
223e47cc LB |
1875 | continue; |
1876 | ||
1877 | // There can be only one. | |
970d7e83 | 1878 | return Attrs.removeAttribute(C, Index, Attribute::Nest); |
223e47cc LB |
1879 | } |
1880 | ||
1881 | return Attrs; | |
1882 | } | |
1883 | ||
1884 | static void RemoveNestAttribute(Function *F) { | |
970d7e83 | 1885 | F->setAttributes(StripNest(F->getContext(), F->getAttributes())); |
1a4d82fc JJ |
1886 | for (User *U : F->users()) { |
1887 | if (isa<BlockAddress>(U)) | |
223e47cc | 1888 | continue; |
1a4d82fc JJ |
1889 | CallSite CS(cast<Instruction>(U)); |
1890 | CS.setAttributes(StripNest(F->getContext(), CS.getAttributes())); | |
223e47cc LB |
1891 | } |
1892 | } | |
1893 | ||
1a4d82fc JJ |
1894 | /// Return true if this is a calling convention that we'd like to change. The |
1895 | /// idea here is that we don't want to mess with the convention if the user | |
1896 | /// explicitly requested something with performance implications like coldcc, | |
1897 | /// GHC, or anyregcc. | |
1898 | static bool isProfitableToMakeFastCC(Function *F) { | |
1899 | CallingConv::ID CC = F->getCallingConv(); | |
1900 | // FIXME: Is it worth transforming x86_stdcallcc and x86_fastcallcc? | |
1901 | return CC == CallingConv::C || CC == CallingConv::X86_ThisCall; | |
1902 | } | |
1903 | ||
223e47cc LB |
1904 | bool GlobalOpt::OptimizeFunctions(Module &M) { |
1905 | bool Changed = false; | |
1906 | // Optimize functions. | |
1907 | for (Module::iterator FI = M.begin(), E = M.end(); FI != E; ) { | |
1908 | Function *F = FI++; | |
1909 | // Functions without names cannot be referenced outside this module. | |
1a4d82fc | 1910 | if (!F->hasName() && !F->isDeclaration() && !F->hasLocalLinkage()) |
223e47cc | 1911 | F->setLinkage(GlobalValue::InternalLinkage); |
85aaf69f SL |
1912 | |
1913 | const Comdat *C = F->getComdat(); | |
1914 | bool inComdat = C && NotDiscardableComdats.count(C); | |
223e47cc | 1915 | F->removeDeadConstantUsers(); |
85aaf69f | 1916 | if ((!inComdat || F->hasLocalLinkage()) && F->isDefTriviallyDead()) { |
223e47cc LB |
1917 | F->eraseFromParent(); |
1918 | Changed = true; | |
1919 | ++NumFnDeleted; | |
1920 | } else if (F->hasLocalLinkage()) { | |
1a4d82fc | 1921 | if (isProfitableToMakeFastCC(F) && !F->isVarArg() && |
223e47cc | 1922 | !F->hasAddressTaken()) { |
1a4d82fc JJ |
1923 | // If this function has a calling convention worth changing, is not a |
1924 | // varargs function, and is only called directly, promote it to use the | |
1925 | // Fast calling convention. | |
223e47cc LB |
1926 | F->setCallingConv(CallingConv::Fast); |
1927 | ChangeCalleesToFastCall(F); | |
1928 | ++NumFastCallFns; | |
1929 | Changed = true; | |
1930 | } | |
1931 | ||
1932 | if (F->getAttributes().hasAttrSomewhere(Attribute::Nest) && | |
1933 | !F->hasAddressTaken()) { | |
1934 | // The function is not used by a trampoline intrinsic, so it is safe | |
1935 | // to remove the 'nest' attribute. | |
1936 | RemoveNestAttribute(F); | |
1937 | ++NumNestRemoved; | |
1938 | Changed = true; | |
1939 | } | |
1940 | } | |
1941 | } | |
1942 | return Changed; | |
1943 | } | |
1944 | ||
1945 | bool GlobalOpt::OptimizeGlobalVars(Module &M) { | |
1946 | bool Changed = false; | |
1a4d82fc | 1947 | |
223e47cc LB |
1948 | for (Module::global_iterator GVI = M.global_begin(), E = M.global_end(); |
1949 | GVI != E; ) { | |
1950 | GlobalVariable *GV = GVI++; | |
1951 | // Global variables without names cannot be referenced outside this module. | |
1a4d82fc | 1952 | if (!GV->hasName() && !GV->isDeclaration() && !GV->hasLocalLinkage()) |
223e47cc LB |
1953 | GV->setLinkage(GlobalValue::InternalLinkage); |
1954 | // Simplify the initializer. | |
1955 | if (GV->hasInitializer()) | |
1956 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GV->getInitializer())) { | |
1a4d82fc | 1957 | Constant *New = ConstantFoldConstantExpression(CE, DL, TLI); |
223e47cc LB |
1958 | if (New && New != CE) |
1959 | GV->setInitializer(New); | |
1960 | } | |
1961 | ||
1a4d82fc JJ |
1962 | if (GV->isDiscardableIfUnused()) { |
1963 | if (const Comdat *C = GV->getComdat()) | |
85aaf69f | 1964 | if (NotDiscardableComdats.count(C) && !GV->hasLocalLinkage()) |
1a4d82fc JJ |
1965 | continue; |
1966 | Changed |= ProcessGlobal(GV, GVI); | |
223e47cc | 1967 | } |
223e47cc | 1968 | } |
1a4d82fc | 1969 | return Changed; |
223e47cc LB |
1970 | } |
1971 | ||
970d7e83 | 1972 | static inline bool |
223e47cc | 1973 | isSimpleEnoughValueToCommit(Constant *C, |
1a4d82fc JJ |
1974 | SmallPtrSetImpl<Constant*> &SimpleConstants, |
1975 | const DataLayout *DL); | |
223e47cc LB |
1976 | |
1977 | ||
1978 | /// isSimpleEnoughValueToCommit - Return true if the specified constant can be | |
1979 | /// handled by the code generator. We don't want to generate something like: | |
1980 | /// void *X = &X/42; | |
1981 | /// because the code generator doesn't have a relocation that can handle that. | |
1982 | /// | |
1983 | /// This function should be called if C was not found (but just got inserted) | |
1984 | /// in SimpleConstants to avoid having to rescan the same constants all the | |
1985 | /// time. | |
1986 | static bool isSimpleEnoughValueToCommitHelper(Constant *C, | |
1a4d82fc JJ |
1987 | SmallPtrSetImpl<Constant*> &SimpleConstants, |
1988 | const DataLayout *DL) { | |
1989 | // Simple global addresses are supported, do not allow dllimport or | |
1990 | // thread-local globals. | |
1991 | if (auto *GV = dyn_cast<GlobalValue>(C)) | |
1992 | return !GV->hasDLLImportStorageClass() && !GV->isThreadLocal(); | |
1993 | ||
1994 | // Simple integer, undef, constant aggregate zero, etc are all supported. | |
1995 | if (C->getNumOperands() == 0 || isa<BlockAddress>(C)) | |
223e47cc | 1996 | return true; |
970d7e83 | 1997 | |
223e47cc LB |
1998 | // Aggregate values are safe if all their elements are. |
1999 | if (isa<ConstantArray>(C) || isa<ConstantStruct>(C) || | |
2000 | isa<ConstantVector>(C)) { | |
2001 | for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i) { | |
2002 | Constant *Op = cast<Constant>(C->getOperand(i)); | |
1a4d82fc | 2003 | if (!isSimpleEnoughValueToCommit(Op, SimpleConstants, DL)) |
223e47cc LB |
2004 | return false; |
2005 | } | |
2006 | return true; | |
2007 | } | |
970d7e83 | 2008 | |
223e47cc LB |
2009 | // We don't know exactly what relocations are allowed in constant expressions, |
2010 | // so we allow &global+constantoffset, which is safe and uniformly supported | |
2011 | // across targets. | |
2012 | ConstantExpr *CE = cast<ConstantExpr>(C); | |
2013 | switch (CE->getOpcode()) { | |
2014 | case Instruction::BitCast: | |
2015 | // Bitcast is fine if the casted value is fine. | |
1a4d82fc | 2016 | return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL); |
223e47cc LB |
2017 | |
2018 | case Instruction::IntToPtr: | |
2019 | case Instruction::PtrToInt: | |
2020 | // int <=> ptr is fine if the int type is the same size as the | |
2021 | // pointer type. | |
1a4d82fc JJ |
2022 | if (!DL || DL->getTypeSizeInBits(CE->getType()) != |
2023 | DL->getTypeSizeInBits(CE->getOperand(0)->getType())) | |
223e47cc | 2024 | return false; |
1a4d82fc | 2025 | return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL); |
970d7e83 | 2026 | |
223e47cc LB |
2027 | // GEP is fine if it is simple + constant offset. |
2028 | case Instruction::GetElementPtr: | |
2029 | for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i) | |
2030 | if (!isa<ConstantInt>(CE->getOperand(i))) | |
2031 | return false; | |
1a4d82fc | 2032 | return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL); |
970d7e83 | 2033 | |
223e47cc LB |
2034 | case Instruction::Add: |
2035 | // We allow simple+cst. | |
2036 | if (!isa<ConstantInt>(CE->getOperand(1))) | |
2037 | return false; | |
1a4d82fc | 2038 | return isSimpleEnoughValueToCommit(CE->getOperand(0), SimpleConstants, DL); |
223e47cc LB |
2039 | } |
2040 | return false; | |
2041 | } | |
2042 | ||
970d7e83 | 2043 | static inline bool |
223e47cc | 2044 | isSimpleEnoughValueToCommit(Constant *C, |
1a4d82fc JJ |
2045 | SmallPtrSetImpl<Constant*> &SimpleConstants, |
2046 | const DataLayout *DL) { | |
223e47cc | 2047 | // If we already checked this constant, we win. |
85aaf69f SL |
2048 | if (!SimpleConstants.insert(C).second) |
2049 | return true; | |
223e47cc | 2050 | // Check the constant. |
1a4d82fc | 2051 | return isSimpleEnoughValueToCommitHelper(C, SimpleConstants, DL); |
223e47cc LB |
2052 | } |
2053 | ||
2054 | ||
2055 | /// isSimpleEnoughPointerToCommit - Return true if this constant is simple | |
2056 | /// enough for us to understand. In particular, if it is a cast to anything | |
2057 | /// other than from one pointer type to another pointer type, we punt. | |
2058 | /// We basically just support direct accesses to globals and GEP's of | |
2059 | /// globals. This should be kept up to date with CommitValueTo. | |
2060 | static bool isSimpleEnoughPointerToCommit(Constant *C) { | |
2061 | // Conservatively, avoid aggregate types. This is because we don't | |
2062 | // want to worry about them partially overlapping other stores. | |
2063 | if (!cast<PointerType>(C->getType())->getElementType()->isSingleValueType()) | |
2064 | return false; | |
2065 | ||
2066 | if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) | |
1a4d82fc | 2067 | // Do not allow weak/*_odr/linkonce linkage or external globals. |
223e47cc LB |
2068 | return GV->hasUniqueInitializer(); |
2069 | ||
2070 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) { | |
2071 | // Handle a constantexpr gep. | |
2072 | if (CE->getOpcode() == Instruction::GetElementPtr && | |
2073 | isa<GlobalVariable>(CE->getOperand(0)) && | |
2074 | cast<GEPOperator>(CE)->isInBounds()) { | |
2075 | GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0)); | |
2076 | // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or | |
2077 | // external globals. | |
2078 | if (!GV->hasUniqueInitializer()) | |
2079 | return false; | |
2080 | ||
2081 | // The first index must be zero. | |
1a4d82fc | 2082 | ConstantInt *CI = dyn_cast<ConstantInt>(*std::next(CE->op_begin())); |
223e47cc LB |
2083 | if (!CI || !CI->isZero()) return false; |
2084 | ||
2085 | // The remaining indices must be compile-time known integers within the | |
2086 | // notional bounds of the corresponding static array types. | |
2087 | if (!CE->isGEPWithNoNotionalOverIndexing()) | |
2088 | return false; | |
2089 | ||
2090 | return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE); | |
970d7e83 | 2091 | |
223e47cc LB |
2092 | // A constantexpr bitcast from a pointer to another pointer is a no-op, |
2093 | // and we know how to evaluate it by moving the bitcast from the pointer | |
2094 | // operand to the value operand. | |
2095 | } else if (CE->getOpcode() == Instruction::BitCast && | |
2096 | isa<GlobalVariable>(CE->getOperand(0))) { | |
2097 | // Do not allow weak/*_odr/linkonce/dllimport/dllexport linkage or | |
2098 | // external globals. | |
2099 | return cast<GlobalVariable>(CE->getOperand(0))->hasUniqueInitializer(); | |
2100 | } | |
2101 | } | |
970d7e83 | 2102 | |
223e47cc LB |
2103 | return false; |
2104 | } | |
2105 | ||
2106 | /// EvaluateStoreInto - Evaluate a piece of a constantexpr store into a global | |
2107 | /// initializer. This returns 'Init' modified to reflect 'Val' stored into it. | |
2108 | /// At this point, the GEP operands of Addr [0, OpNo) have been stepped into. | |
2109 | static Constant *EvaluateStoreInto(Constant *Init, Constant *Val, | |
2110 | ConstantExpr *Addr, unsigned OpNo) { | |
2111 | // Base case of the recursion. | |
2112 | if (OpNo == Addr->getNumOperands()) { | |
2113 | assert(Val->getType() == Init->getType() && "Type mismatch!"); | |
2114 | return Val; | |
2115 | } | |
2116 | ||
2117 | SmallVector<Constant*, 32> Elts; | |
2118 | if (StructType *STy = dyn_cast<StructType>(Init->getType())) { | |
2119 | // Break up the constant into its elements. | |
2120 | for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) | |
2121 | Elts.push_back(Init->getAggregateElement(i)); | |
2122 | ||
2123 | // Replace the element that we are supposed to. | |
2124 | ConstantInt *CU = cast<ConstantInt>(Addr->getOperand(OpNo)); | |
2125 | unsigned Idx = CU->getZExtValue(); | |
2126 | assert(Idx < STy->getNumElements() && "Struct index out of range!"); | |
2127 | Elts[Idx] = EvaluateStoreInto(Elts[Idx], Val, Addr, OpNo+1); | |
2128 | ||
2129 | // Return the modified struct. | |
2130 | return ConstantStruct::get(STy, Elts); | |
2131 | } | |
970d7e83 | 2132 | |
223e47cc LB |
2133 | ConstantInt *CI = cast<ConstantInt>(Addr->getOperand(OpNo)); |
2134 | SequentialType *InitTy = cast<SequentialType>(Init->getType()); | |
2135 | ||
2136 | uint64_t NumElts; | |
2137 | if (ArrayType *ATy = dyn_cast<ArrayType>(InitTy)) | |
2138 | NumElts = ATy->getNumElements(); | |
2139 | else | |
2140 | NumElts = InitTy->getVectorNumElements(); | |
2141 | ||
2142 | // Break up the array into elements. | |
2143 | for (uint64_t i = 0, e = NumElts; i != e; ++i) | |
2144 | Elts.push_back(Init->getAggregateElement(i)); | |
2145 | ||
2146 | assert(CI->getZExtValue() < NumElts); | |
2147 | Elts[CI->getZExtValue()] = | |
2148 | EvaluateStoreInto(Elts[CI->getZExtValue()], Val, Addr, OpNo+1); | |
2149 | ||
2150 | if (Init->getType()->isArrayTy()) | |
2151 | return ConstantArray::get(cast<ArrayType>(InitTy), Elts); | |
2152 | return ConstantVector::get(Elts); | |
2153 | } | |
2154 | ||
2155 | /// CommitValueTo - We have decided that Addr (which satisfies the predicate | |
2156 | /// isSimpleEnoughPointerToCommit) should get Val as its value. Make it happen. | |
2157 | static void CommitValueTo(Constant *Val, Constant *Addr) { | |
2158 | if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) { | |
2159 | assert(GV->hasInitializer()); | |
2160 | GV->setInitializer(Val); | |
2161 | return; | |
2162 | } | |
2163 | ||
2164 | ConstantExpr *CE = cast<ConstantExpr>(Addr); | |
2165 | GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0)); | |
2166 | GV->setInitializer(EvaluateStoreInto(GV->getInitializer(), Val, CE, 2)); | |
2167 | } | |
2168 | ||
2169 | namespace { | |
2170 | ||
2171 | /// Evaluator - This class evaluates LLVM IR, producing the Constant | |
2172 | /// representing each SSA instruction. Changes to global variables are stored | |
2173 | /// in a mapping that can be iterated over after the evaluation is complete. | |
2174 | /// Once an evaluation call fails, the evaluation object should not be reused. | |
2175 | class Evaluator { | |
2176 | public: | |
1a4d82fc JJ |
2177 | Evaluator(const DataLayout *DL, const TargetLibraryInfo *TLI) |
2178 | : DL(DL), TLI(TLI) { | |
2179 | ValueStack.emplace_back(); | |
223e47cc LB |
2180 | } |
2181 | ||
2182 | ~Evaluator() { | |
1a4d82fc | 2183 | for (auto &Tmp : AllocaTmps) |
223e47cc LB |
2184 | // If there are still users of the alloca, the program is doing something |
2185 | // silly, e.g. storing the address of the alloca somewhere and using it | |
2186 | // later. Since this is undefined, we'll just make it be null. | |
2187 | if (!Tmp->use_empty()) | |
2188 | Tmp->replaceAllUsesWith(Constant::getNullValue(Tmp->getType())); | |
223e47cc LB |
2189 | } |
2190 | ||
2191 | /// EvaluateFunction - Evaluate a call to function F, returning true if | |
2192 | /// successful, false if we can't evaluate it. ActualArgs contains the formal | |
2193 | /// arguments for the function. | |
2194 | bool EvaluateFunction(Function *F, Constant *&RetVal, | |
2195 | const SmallVectorImpl<Constant*> &ActualArgs); | |
2196 | ||
2197 | /// EvaluateBlock - Evaluate all instructions in block BB, returning true if | |
2198 | /// successful, false if we can't evaluate it. NewBB returns the next BB that | |
2199 | /// control flows into, or null upon return. | |
2200 | bool EvaluateBlock(BasicBlock::iterator CurInst, BasicBlock *&NextBB); | |
2201 | ||
2202 | Constant *getVal(Value *V) { | |
2203 | if (Constant *CV = dyn_cast<Constant>(V)) return CV; | |
1a4d82fc | 2204 | Constant *R = ValueStack.back().lookup(V); |
223e47cc LB |
2205 | assert(R && "Reference to an uncomputed value!"); |
2206 | return R; | |
2207 | } | |
2208 | ||
2209 | void setVal(Value *V, Constant *C) { | |
1a4d82fc | 2210 | ValueStack.back()[V] = C; |
223e47cc LB |
2211 | } |
2212 | ||
2213 | const DenseMap<Constant*, Constant*> &getMutatedMemory() const { | |
2214 | return MutatedMemory; | |
2215 | } | |
2216 | ||
1a4d82fc | 2217 | const SmallPtrSetImpl<GlobalVariable*> &getInvariants() const { |
223e47cc LB |
2218 | return Invariants; |
2219 | } | |
2220 | ||
2221 | private: | |
2222 | Constant *ComputeLoadResult(Constant *P); | |
2223 | ||
2224 | /// ValueStack - As we compute SSA register values, we store their contents | |
1a4d82fc | 2225 | /// here. The back of the deque contains the current function and the stack |
223e47cc | 2226 | /// contains the values in the calling frames. |
1a4d82fc | 2227 | std::deque<DenseMap<Value*, Constant*>> ValueStack; |
223e47cc LB |
2228 | |
2229 | /// CallStack - This is used to detect recursion. In pathological situations | |
2230 | /// we could hit exponential behavior, but at least there is nothing | |
2231 | /// unbounded. | |
2232 | SmallVector<Function*, 4> CallStack; | |
2233 | ||
2234 | /// MutatedMemory - For each store we execute, we update this map. Loads | |
2235 | /// check this to get the most up-to-date value. If evaluation is successful, | |
2236 | /// this state is committed to the process. | |
2237 | DenseMap<Constant*, Constant*> MutatedMemory; | |
2238 | ||
2239 | /// AllocaTmps - To 'execute' an alloca, we create a temporary global variable | |
2240 | /// to represent its body. This vector is needed so we can delete the | |
2241 | /// temporary globals when we are done. | |
1a4d82fc | 2242 | SmallVector<std::unique_ptr<GlobalVariable>, 32> AllocaTmps; |
223e47cc LB |
2243 | |
2244 | /// Invariants - These global variables have been marked invariant by the | |
2245 | /// static constructor. | |
2246 | SmallPtrSet<GlobalVariable*, 8> Invariants; | |
2247 | ||
2248 | /// SimpleConstants - These are constants we have checked and know to be | |
2249 | /// simple enough to live in a static initializer of a global. | |
2250 | SmallPtrSet<Constant*, 8> SimpleConstants; | |
2251 | ||
1a4d82fc | 2252 | const DataLayout *DL; |
223e47cc LB |
2253 | const TargetLibraryInfo *TLI; |
2254 | }; | |
2255 | ||
2256 | } // anonymous namespace | |
2257 | ||
2258 | /// ComputeLoadResult - Return the value that would be computed by a load from | |
2259 | /// P after the stores reflected by 'memory' have been performed. If we can't | |
2260 | /// decide, return null. | |
2261 | Constant *Evaluator::ComputeLoadResult(Constant *P) { | |
2262 | // If this memory location has been recently stored, use the stored value: it | |
2263 | // is the most up-to-date. | |
2264 | DenseMap<Constant*, Constant*>::const_iterator I = MutatedMemory.find(P); | |
2265 | if (I != MutatedMemory.end()) return I->second; | |
2266 | ||
2267 | // Access it. | |
2268 | if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P)) { | |
2269 | if (GV->hasDefinitiveInitializer()) | |
2270 | return GV->getInitializer(); | |
1a4d82fc | 2271 | return nullptr; |
223e47cc LB |
2272 | } |
2273 | ||
2274 | // Handle a constantexpr getelementptr. | |
2275 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(P)) | |
2276 | if (CE->getOpcode() == Instruction::GetElementPtr && | |
2277 | isa<GlobalVariable>(CE->getOperand(0))) { | |
2278 | GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0)); | |
2279 | if (GV->hasDefinitiveInitializer()) | |
2280 | return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE); | |
2281 | } | |
2282 | ||
1a4d82fc | 2283 | return nullptr; // don't know how to evaluate. |
223e47cc LB |
2284 | } |
2285 | ||
2286 | /// EvaluateBlock - Evaluate all instructions in block BB, returning true if | |
2287 | /// successful, false if we can't evaluate it. NewBB returns the next BB that | |
2288 | /// control flows into, or null upon return. | |
2289 | bool Evaluator::EvaluateBlock(BasicBlock::iterator CurInst, | |
2290 | BasicBlock *&NextBB) { | |
2291 | // This is the main evaluation loop. | |
2292 | while (1) { | |
1a4d82fc | 2293 | Constant *InstResult = nullptr; |
223e47cc | 2294 | |
970d7e83 LB |
2295 | DEBUG(dbgs() << "Evaluating Instruction: " << *CurInst << "\n"); |
2296 | ||
223e47cc | 2297 | if (StoreInst *SI = dyn_cast<StoreInst>(CurInst)) { |
970d7e83 LB |
2298 | if (!SI->isSimple()) { |
2299 | DEBUG(dbgs() << "Store is not simple! Can not evaluate.\n"); | |
2300 | return false; // no volatile/atomic accesses. | |
2301 | } | |
223e47cc | 2302 | Constant *Ptr = getVal(SI->getOperand(1)); |
970d7e83 LB |
2303 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) { |
2304 | DEBUG(dbgs() << "Folding constant ptr expression: " << *Ptr); | |
1a4d82fc | 2305 | Ptr = ConstantFoldConstantExpression(CE, DL, TLI); |
970d7e83 LB |
2306 | DEBUG(dbgs() << "; To: " << *Ptr << "\n"); |
2307 | } | |
2308 | if (!isSimpleEnoughPointerToCommit(Ptr)) { | |
223e47cc | 2309 | // If this is too complex for us to commit, reject it. |
970d7e83 | 2310 | DEBUG(dbgs() << "Pointer is too complex for us to evaluate store."); |
223e47cc | 2311 | return false; |
970d7e83 LB |
2312 | } |
2313 | ||
223e47cc LB |
2314 | Constant *Val = getVal(SI->getOperand(0)); |
2315 | ||
2316 | // If this might be too difficult for the backend to handle (e.g. the addr | |
2317 | // of one global variable divided by another) then we can't commit it. | |
1a4d82fc | 2318 | if (!isSimpleEnoughValueToCommit(Val, SimpleConstants, DL)) { |
970d7e83 LB |
2319 | DEBUG(dbgs() << "Store value is too complex to evaluate store. " << *Val |
2320 | << "\n"); | |
223e47cc | 2321 | return false; |
970d7e83 LB |
2322 | } |
2323 | ||
2324 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) { | |
223e47cc | 2325 | if (CE->getOpcode() == Instruction::BitCast) { |
970d7e83 | 2326 | DEBUG(dbgs() << "Attempting to resolve bitcast on constant ptr.\n"); |
223e47cc LB |
2327 | // If we're evaluating a store through a bitcast, then we need |
2328 | // to pull the bitcast off the pointer type and push it onto the | |
2329 | // stored value. | |
2330 | Ptr = CE->getOperand(0); | |
970d7e83 | 2331 | |
223e47cc | 2332 | Type *NewTy = cast<PointerType>(Ptr->getType())->getElementType(); |
970d7e83 | 2333 | |
223e47cc LB |
2334 | // In order to push the bitcast onto the stored value, a bitcast |
2335 | // from NewTy to Val's type must be legal. If it's not, we can try | |
2336 | // introspecting NewTy to find a legal conversion. | |
2337 | while (!Val->getType()->canLosslesslyBitCastTo(NewTy)) { | |
2338 | // If NewTy is a struct, we can convert the pointer to the struct | |
2339 | // into a pointer to its first member. | |
2340 | // FIXME: This could be extended to support arrays as well. | |
2341 | if (StructType *STy = dyn_cast<StructType>(NewTy)) { | |
2342 | NewTy = STy->getTypeAtIndex(0U); | |
2343 | ||
2344 | IntegerType *IdxTy = IntegerType::get(NewTy->getContext(), 32); | |
2345 | Constant *IdxZero = ConstantInt::get(IdxTy, 0, false); | |
2346 | Constant * const IdxList[] = {IdxZero, IdxZero}; | |
2347 | ||
2348 | Ptr = ConstantExpr::getGetElementPtr(Ptr, IdxList); | |
2349 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) | |
1a4d82fc | 2350 | Ptr = ConstantFoldConstantExpression(CE, DL, TLI); |
223e47cc LB |
2351 | |
2352 | // If we can't improve the situation by introspecting NewTy, | |
2353 | // we have to give up. | |
2354 | } else { | |
970d7e83 LB |
2355 | DEBUG(dbgs() << "Failed to bitcast constant ptr, can not " |
2356 | "evaluate.\n"); | |
223e47cc LB |
2357 | return false; |
2358 | } | |
2359 | } | |
970d7e83 | 2360 | |
223e47cc LB |
2361 | // If we found compatible types, go ahead and push the bitcast |
2362 | // onto the stored value. | |
2363 | Val = ConstantExpr::getBitCast(Val, NewTy); | |
970d7e83 LB |
2364 | |
2365 | DEBUG(dbgs() << "Evaluated bitcast: " << *Val << "\n"); | |
223e47cc | 2366 | } |
970d7e83 LB |
2367 | } |
2368 | ||
223e47cc LB |
2369 | MutatedMemory[Ptr] = Val; |
2370 | } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CurInst)) { | |
2371 | InstResult = ConstantExpr::get(BO->getOpcode(), | |
2372 | getVal(BO->getOperand(0)), | |
2373 | getVal(BO->getOperand(1))); | |
970d7e83 LB |
2374 | DEBUG(dbgs() << "Found a BinaryOperator! Simplifying: " << *InstResult |
2375 | << "\n"); | |
223e47cc LB |
2376 | } else if (CmpInst *CI = dyn_cast<CmpInst>(CurInst)) { |
2377 | InstResult = ConstantExpr::getCompare(CI->getPredicate(), | |
2378 | getVal(CI->getOperand(0)), | |
2379 | getVal(CI->getOperand(1))); | |
970d7e83 LB |
2380 | DEBUG(dbgs() << "Found a CmpInst! Simplifying: " << *InstResult |
2381 | << "\n"); | |
223e47cc LB |
2382 | } else if (CastInst *CI = dyn_cast<CastInst>(CurInst)) { |
2383 | InstResult = ConstantExpr::getCast(CI->getOpcode(), | |
2384 | getVal(CI->getOperand(0)), | |
2385 | CI->getType()); | |
970d7e83 LB |
2386 | DEBUG(dbgs() << "Found a Cast! Simplifying: " << *InstResult |
2387 | << "\n"); | |
223e47cc LB |
2388 | } else if (SelectInst *SI = dyn_cast<SelectInst>(CurInst)) { |
2389 | InstResult = ConstantExpr::getSelect(getVal(SI->getOperand(0)), | |
2390 | getVal(SI->getOperand(1)), | |
2391 | getVal(SI->getOperand(2))); | |
970d7e83 LB |
2392 | DEBUG(dbgs() << "Found a Select! Simplifying: " << *InstResult |
2393 | << "\n"); | |
1a4d82fc JJ |
2394 | } else if (auto *EVI = dyn_cast<ExtractValueInst>(CurInst)) { |
2395 | InstResult = ConstantExpr::getExtractValue( | |
2396 | getVal(EVI->getAggregateOperand()), EVI->getIndices()); | |
2397 | DEBUG(dbgs() << "Found an ExtractValueInst! Simplifying: " << *InstResult | |
2398 | << "\n"); | |
2399 | } else if (auto *IVI = dyn_cast<InsertValueInst>(CurInst)) { | |
2400 | InstResult = ConstantExpr::getInsertValue( | |
2401 | getVal(IVI->getAggregateOperand()), | |
2402 | getVal(IVI->getInsertedValueOperand()), IVI->getIndices()); | |
2403 | DEBUG(dbgs() << "Found an InsertValueInst! Simplifying: " << *InstResult | |
2404 | << "\n"); | |
223e47cc LB |
2405 | } else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(CurInst)) { |
2406 | Constant *P = getVal(GEP->getOperand(0)); | |
2407 | SmallVector<Constant*, 8> GEPOps; | |
2408 | for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); | |
2409 | i != e; ++i) | |
2410 | GEPOps.push_back(getVal(*i)); | |
2411 | InstResult = | |
2412 | ConstantExpr::getGetElementPtr(P, GEPOps, | |
2413 | cast<GEPOperator>(GEP)->isInBounds()); | |
970d7e83 LB |
2414 | DEBUG(dbgs() << "Found a GEP! Simplifying: " << *InstResult |
2415 | << "\n"); | |
223e47cc | 2416 | } else if (LoadInst *LI = dyn_cast<LoadInst>(CurInst)) { |
970d7e83 LB |
2417 | |
2418 | if (!LI->isSimple()) { | |
2419 | DEBUG(dbgs() << "Found a Load! Not a simple load, can not evaluate.\n"); | |
2420 | return false; // no volatile/atomic accesses. | |
2421 | } | |
2422 | ||
223e47cc | 2423 | Constant *Ptr = getVal(LI->getOperand(0)); |
970d7e83 | 2424 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ptr)) { |
1a4d82fc | 2425 | Ptr = ConstantFoldConstantExpression(CE, DL, TLI); |
970d7e83 LB |
2426 | DEBUG(dbgs() << "Found a constant pointer expression, constant " |
2427 | "folding: " << *Ptr << "\n"); | |
2428 | } | |
223e47cc | 2429 | InstResult = ComputeLoadResult(Ptr); |
1a4d82fc | 2430 | if (!InstResult) { |
970d7e83 LB |
2431 | DEBUG(dbgs() << "Failed to compute load result. Can not evaluate load." |
2432 | "\n"); | |
2433 | return false; // Could not evaluate load. | |
2434 | } | |
2435 | ||
2436 | DEBUG(dbgs() << "Evaluated load: " << *InstResult << "\n"); | |
223e47cc | 2437 | } else if (AllocaInst *AI = dyn_cast<AllocaInst>(CurInst)) { |
970d7e83 LB |
2438 | if (AI->isArrayAllocation()) { |
2439 | DEBUG(dbgs() << "Found an array alloca. Can not evaluate.\n"); | |
2440 | return false; // Cannot handle array allocs. | |
2441 | } | |
223e47cc | 2442 | Type *Ty = AI->getType()->getElementType(); |
1a4d82fc JJ |
2443 | AllocaTmps.push_back( |
2444 | make_unique<GlobalVariable>(Ty, false, GlobalValue::InternalLinkage, | |
2445 | UndefValue::get(Ty), AI->getName())); | |
2446 | InstResult = AllocaTmps.back().get(); | |
970d7e83 | 2447 | DEBUG(dbgs() << "Found an alloca. Result: " << *InstResult << "\n"); |
223e47cc LB |
2448 | } else if (isa<CallInst>(CurInst) || isa<InvokeInst>(CurInst)) { |
2449 | CallSite CS(CurInst); | |
2450 | ||
2451 | // Debug info can safely be ignored here. | |
2452 | if (isa<DbgInfoIntrinsic>(CS.getInstruction())) { | |
970d7e83 | 2453 | DEBUG(dbgs() << "Ignoring debug info.\n"); |
223e47cc LB |
2454 | ++CurInst; |
2455 | continue; | |
2456 | } | |
2457 | ||
2458 | // Cannot handle inline asm. | |
970d7e83 LB |
2459 | if (isa<InlineAsm>(CS.getCalledValue())) { |
2460 | DEBUG(dbgs() << "Found inline asm, can not evaluate.\n"); | |
2461 | return false; | |
2462 | } | |
223e47cc LB |
2463 | |
2464 | if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CS.getInstruction())) { | |
2465 | if (MemSetInst *MSI = dyn_cast<MemSetInst>(II)) { | |
970d7e83 LB |
2466 | if (MSI->isVolatile()) { |
2467 | DEBUG(dbgs() << "Can not optimize a volatile memset " << | |
2468 | "intrinsic.\n"); | |
2469 | return false; | |
2470 | } | |
223e47cc LB |
2471 | Constant *Ptr = getVal(MSI->getDest()); |
2472 | Constant *Val = getVal(MSI->getValue()); | |
2473 | Constant *DestVal = ComputeLoadResult(getVal(Ptr)); | |
2474 | if (Val->isNullValue() && DestVal && DestVal->isNullValue()) { | |
2475 | // This memset is a no-op. | |
970d7e83 | 2476 | DEBUG(dbgs() << "Ignoring no-op memset.\n"); |
223e47cc LB |
2477 | ++CurInst; |
2478 | continue; | |
2479 | } | |
2480 | } | |
2481 | ||
2482 | if (II->getIntrinsicID() == Intrinsic::lifetime_start || | |
2483 | II->getIntrinsicID() == Intrinsic::lifetime_end) { | |
970d7e83 | 2484 | DEBUG(dbgs() << "Ignoring lifetime intrinsic.\n"); |
223e47cc LB |
2485 | ++CurInst; |
2486 | continue; | |
2487 | } | |
2488 | ||
2489 | if (II->getIntrinsicID() == Intrinsic::invariant_start) { | |
2490 | // We don't insert an entry into Values, as it doesn't have a | |
2491 | // meaningful return value. | |
970d7e83 | 2492 | if (!II->use_empty()) { |
1a4d82fc | 2493 | DEBUG(dbgs() << "Found unused invariant_start. Can't evaluate.\n"); |
223e47cc | 2494 | return false; |
970d7e83 | 2495 | } |
223e47cc LB |
2496 | ConstantInt *Size = cast<ConstantInt>(II->getArgOperand(0)); |
2497 | Value *PtrArg = getVal(II->getArgOperand(1)); | |
2498 | Value *Ptr = PtrArg->stripPointerCasts(); | |
2499 | if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Ptr)) { | |
2500 | Type *ElemTy = cast<PointerType>(GV->getType())->getElementType(); | |
1a4d82fc | 2501 | if (DL && !Size->isAllOnesValue() && |
223e47cc | 2502 | Size->getValue().getLimitedValue() >= |
1a4d82fc | 2503 | DL->getTypeStoreSize(ElemTy)) { |
223e47cc | 2504 | Invariants.insert(GV); |
970d7e83 LB |
2505 | DEBUG(dbgs() << "Found a global var that is an invariant: " << *GV |
2506 | << "\n"); | |
2507 | } else { | |
2508 | DEBUG(dbgs() << "Found a global var, but can not treat it as an " | |
2509 | "invariant.\n"); | |
2510 | } | |
223e47cc LB |
2511 | } |
2512 | // Continue even if we do nothing. | |
2513 | ++CurInst; | |
2514 | continue; | |
2515 | } | |
970d7e83 LB |
2516 | |
2517 | DEBUG(dbgs() << "Unknown intrinsic. Can not evaluate.\n"); | |
223e47cc LB |
2518 | return false; |
2519 | } | |
2520 | ||
2521 | // Resolve function pointers. | |
2522 | Function *Callee = dyn_cast<Function>(getVal(CS.getCalledValue())); | |
970d7e83 LB |
2523 | if (!Callee || Callee->mayBeOverridden()) { |
2524 | DEBUG(dbgs() << "Can not resolve function pointer.\n"); | |
223e47cc | 2525 | return false; // Cannot resolve. |
970d7e83 | 2526 | } |
223e47cc LB |
2527 | |
2528 | SmallVector<Constant*, 8> Formals; | |
2529 | for (User::op_iterator i = CS.arg_begin(), e = CS.arg_end(); i != e; ++i) | |
2530 | Formals.push_back(getVal(*i)); | |
2531 | ||
2532 | if (Callee->isDeclaration()) { | |
2533 | // If this is a function we can constant fold, do it. | |
2534 | if (Constant *C = ConstantFoldCall(Callee, Formals, TLI)) { | |
2535 | InstResult = C; | |
970d7e83 LB |
2536 | DEBUG(dbgs() << "Constant folded function call. Result: " << |
2537 | *InstResult << "\n"); | |
223e47cc | 2538 | } else { |
970d7e83 | 2539 | DEBUG(dbgs() << "Can not constant fold function call.\n"); |
223e47cc LB |
2540 | return false; |
2541 | } | |
2542 | } else { | |
970d7e83 LB |
2543 | if (Callee->getFunctionType()->isVarArg()) { |
2544 | DEBUG(dbgs() << "Can not constant fold vararg function call.\n"); | |
223e47cc | 2545 | return false; |
970d7e83 | 2546 | } |
223e47cc | 2547 | |
1a4d82fc | 2548 | Constant *RetVal = nullptr; |
223e47cc | 2549 | // Execute the call, if successful, use the return value. |
1a4d82fc | 2550 | ValueStack.emplace_back(); |
970d7e83 LB |
2551 | if (!EvaluateFunction(Callee, RetVal, Formals)) { |
2552 | DEBUG(dbgs() << "Failed to evaluate function.\n"); | |
223e47cc | 2553 | return false; |
970d7e83 | 2554 | } |
1a4d82fc | 2555 | ValueStack.pop_back(); |
223e47cc | 2556 | InstResult = RetVal; |
970d7e83 | 2557 | |
1a4d82fc | 2558 | if (InstResult) { |
970d7e83 LB |
2559 | DEBUG(dbgs() << "Successfully evaluated function. Result: " << |
2560 | InstResult << "\n\n"); | |
2561 | } else { | |
2562 | DEBUG(dbgs() << "Successfully evaluated function. Result: 0\n\n"); | |
2563 | } | |
223e47cc LB |
2564 | } |
2565 | } else if (isa<TerminatorInst>(CurInst)) { | |
970d7e83 LB |
2566 | DEBUG(dbgs() << "Found a terminator instruction.\n"); |
2567 | ||
223e47cc LB |
2568 | if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) { |
2569 | if (BI->isUnconditional()) { | |
2570 | NextBB = BI->getSuccessor(0); | |
2571 | } else { | |
2572 | ConstantInt *Cond = | |
2573 | dyn_cast<ConstantInt>(getVal(BI->getCondition())); | |
2574 | if (!Cond) return false; // Cannot determine. | |
2575 | ||
2576 | NextBB = BI->getSuccessor(!Cond->getZExtValue()); | |
2577 | } | |
2578 | } else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) { | |
2579 | ConstantInt *Val = | |
2580 | dyn_cast<ConstantInt>(getVal(SI->getCondition())); | |
2581 | if (!Val) return false; // Cannot determine. | |
2582 | NextBB = SI->findCaseValue(Val).getCaseSuccessor(); | |
2583 | } else if (IndirectBrInst *IBI = dyn_cast<IndirectBrInst>(CurInst)) { | |
2584 | Value *Val = getVal(IBI->getAddress())->stripPointerCasts(); | |
2585 | if (BlockAddress *BA = dyn_cast<BlockAddress>(Val)) | |
2586 | NextBB = BA->getBasicBlock(); | |
2587 | else | |
2588 | return false; // Cannot determine. | |
2589 | } else if (isa<ReturnInst>(CurInst)) { | |
1a4d82fc | 2590 | NextBB = nullptr; |
223e47cc LB |
2591 | } else { |
2592 | // invoke, unwind, resume, unreachable. | |
970d7e83 | 2593 | DEBUG(dbgs() << "Can not handle terminator."); |
223e47cc LB |
2594 | return false; // Cannot handle this terminator. |
2595 | } | |
2596 | ||
2597 | // We succeeded at evaluating this block! | |
970d7e83 | 2598 | DEBUG(dbgs() << "Successfully evaluated block.\n"); |
223e47cc LB |
2599 | return true; |
2600 | } else { | |
2601 | // Did not know how to evaluate this! | |
970d7e83 LB |
2602 | DEBUG(dbgs() << "Failed to evaluate block due to unhandled instruction." |
2603 | "\n"); | |
223e47cc LB |
2604 | return false; |
2605 | } | |
2606 | ||
2607 | if (!CurInst->use_empty()) { | |
2608 | if (ConstantExpr *CE = dyn_cast<ConstantExpr>(InstResult)) | |
1a4d82fc | 2609 | InstResult = ConstantFoldConstantExpression(CE, DL, TLI); |
970d7e83 | 2610 | |
223e47cc LB |
2611 | setVal(CurInst, InstResult); |
2612 | } | |
2613 | ||
2614 | // If we just processed an invoke, we finished evaluating the block. | |
2615 | if (InvokeInst *II = dyn_cast<InvokeInst>(CurInst)) { | |
2616 | NextBB = II->getNormalDest(); | |
970d7e83 | 2617 | DEBUG(dbgs() << "Found an invoke instruction. Finished Block.\n\n"); |
223e47cc LB |
2618 | return true; |
2619 | } | |
2620 | ||
2621 | // Advance program counter. | |
2622 | ++CurInst; | |
2623 | } | |
2624 | } | |
2625 | ||
2626 | /// EvaluateFunction - Evaluate a call to function F, returning true if | |
2627 | /// successful, false if we can't evaluate it. ActualArgs contains the formal | |
2628 | /// arguments for the function. | |
2629 | bool Evaluator::EvaluateFunction(Function *F, Constant *&RetVal, | |
2630 | const SmallVectorImpl<Constant*> &ActualArgs) { | |
2631 | // Check to see if this function is already executing (recursion). If so, | |
2632 | // bail out. TODO: we might want to accept limited recursion. | |
2633 | if (std::find(CallStack.begin(), CallStack.end(), F) != CallStack.end()) | |
2634 | return false; | |
2635 | ||
2636 | CallStack.push_back(F); | |
2637 | ||
2638 | // Initialize arguments to the incoming values specified. | |
2639 | unsigned ArgNo = 0; | |
2640 | for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end(); AI != E; | |
2641 | ++AI, ++ArgNo) | |
2642 | setVal(AI, ActualArgs[ArgNo]); | |
2643 | ||
2644 | // ExecutedBlocks - We only handle non-looping, non-recursive code. As such, | |
2645 | // we can only evaluate any one basic block at most once. This set keeps | |
2646 | // track of what we have executed so we can detect recursive cases etc. | |
2647 | SmallPtrSet<BasicBlock*, 32> ExecutedBlocks; | |
2648 | ||
2649 | // CurBB - The current basic block we're evaluating. | |
2650 | BasicBlock *CurBB = F->begin(); | |
2651 | ||
2652 | BasicBlock::iterator CurInst = CurBB->begin(); | |
2653 | ||
2654 | while (1) { | |
1a4d82fc | 2655 | BasicBlock *NextBB = nullptr; // Initialized to avoid compiler warnings. |
970d7e83 LB |
2656 | DEBUG(dbgs() << "Trying to evaluate BB: " << *CurBB << "\n"); |
2657 | ||
223e47cc LB |
2658 | if (!EvaluateBlock(CurInst, NextBB)) |
2659 | return false; | |
2660 | ||
1a4d82fc | 2661 | if (!NextBB) { |
223e47cc LB |
2662 | // Successfully running until there's no next block means that we found |
2663 | // the return. Fill it the return value and pop the call stack. | |
2664 | ReturnInst *RI = cast<ReturnInst>(CurBB->getTerminator()); | |
2665 | if (RI->getNumOperands()) | |
2666 | RetVal = getVal(RI->getOperand(0)); | |
2667 | CallStack.pop_back(); | |
2668 | return true; | |
2669 | } | |
2670 | ||
2671 | // Okay, we succeeded in evaluating this control flow. See if we have | |
2672 | // executed the new block before. If so, we have a looping function, | |
2673 | // which we cannot evaluate in reasonable time. | |
85aaf69f | 2674 | if (!ExecutedBlocks.insert(NextBB).second) |
223e47cc LB |
2675 | return false; // looped! |
2676 | ||
2677 | // Okay, we have never been in this block before. Check to see if there | |
2678 | // are any PHI nodes. If so, evaluate them with information about where | |
2679 | // we came from. | |
1a4d82fc | 2680 | PHINode *PN = nullptr; |
223e47cc LB |
2681 | for (CurInst = NextBB->begin(); |
2682 | (PN = dyn_cast<PHINode>(CurInst)); ++CurInst) | |
2683 | setVal(PN, getVal(PN->getIncomingValueForBlock(CurBB))); | |
2684 | ||
2685 | // Advance to the next block. | |
2686 | CurBB = NextBB; | |
2687 | } | |
2688 | } | |
2689 | ||
2690 | /// EvaluateStaticConstructor - Evaluate static constructors in the function, if | |
2691 | /// we can. Return true if we can, false otherwise. | |
1a4d82fc | 2692 | static bool EvaluateStaticConstructor(Function *F, const DataLayout *DL, |
223e47cc LB |
2693 | const TargetLibraryInfo *TLI) { |
2694 | // Call the function. | |
1a4d82fc | 2695 | Evaluator Eval(DL, TLI); |
223e47cc LB |
2696 | Constant *RetValDummy; |
2697 | bool EvalSuccess = Eval.EvaluateFunction(F, RetValDummy, | |
2698 | SmallVector<Constant*, 0>()); | |
970d7e83 | 2699 | |
223e47cc | 2700 | if (EvalSuccess) { |
1a4d82fc JJ |
2701 | ++NumCtorsEvaluated; |
2702 | ||
223e47cc LB |
2703 | // We succeeded at evaluation: commit the result. |
2704 | DEBUG(dbgs() << "FULLY EVALUATED GLOBAL CTOR FUNCTION '" | |
2705 | << F->getName() << "' to " << Eval.getMutatedMemory().size() | |
2706 | << " stores.\n"); | |
2707 | for (DenseMap<Constant*, Constant*>::const_iterator I = | |
2708 | Eval.getMutatedMemory().begin(), E = Eval.getMutatedMemory().end(); | |
2709 | I != E; ++I) | |
2710 | CommitValueTo(I->second, I->first); | |
1a4d82fc JJ |
2711 | for (GlobalVariable *GV : Eval.getInvariants()) |
2712 | GV->setConstant(true); | |
223e47cc LB |
2713 | } |
2714 | ||
2715 | return EvalSuccess; | |
2716 | } | |
2717 | ||
1a4d82fc JJ |
2718 | static int compareNames(Constant *const *A, Constant *const *B) { |
2719 | return (*A)->getName().compare((*B)->getName()); | |
2720 | } | |
223e47cc | 2721 | |
1a4d82fc JJ |
2722 | static void setUsedInitializer(GlobalVariable &V, |
2723 | const SmallPtrSet<GlobalValue *, 8> &Init) { | |
2724 | if (Init.empty()) { | |
2725 | V.eraseFromParent(); | |
2726 | return; | |
2727 | } | |
223e47cc | 2728 | |
1a4d82fc JJ |
2729 | // Type of pointer to the array of pointers. |
2730 | PointerType *Int8PtrTy = Type::getInt8PtrTy(V.getContext(), 0); | |
2731 | ||
2732 | SmallVector<llvm::Constant *, 8> UsedArray; | |
2733 | for (GlobalValue *GV : Init) { | |
2734 | Constant *Cast | |
2735 | = ConstantExpr::getPointerBitCastOrAddrSpaceCast(GV, Int8PtrTy); | |
2736 | UsedArray.push_back(Cast); | |
2737 | } | |
2738 | // Sort to get deterministic order. | |
2739 | array_pod_sort(UsedArray.begin(), UsedArray.end(), compareNames); | |
2740 | ArrayType *ATy = ArrayType::get(Int8PtrTy, UsedArray.size()); | |
2741 | ||
2742 | Module *M = V.getParent(); | |
2743 | V.removeFromParent(); | |
2744 | GlobalVariable *NV = | |
2745 | new GlobalVariable(*M, ATy, false, llvm::GlobalValue::AppendingLinkage, | |
2746 | llvm::ConstantArray::get(ATy, UsedArray), ""); | |
2747 | NV->takeName(&V); | |
2748 | NV->setSection("llvm.metadata"); | |
2749 | delete &V; | |
2750 | } | |
2751 | ||
2752 | namespace { | |
2753 | /// \brief An easy to access representation of llvm.used and llvm.compiler.used. | |
2754 | class LLVMUsed { | |
2755 | SmallPtrSet<GlobalValue *, 8> Used; | |
2756 | SmallPtrSet<GlobalValue *, 8> CompilerUsed; | |
2757 | GlobalVariable *UsedV; | |
2758 | GlobalVariable *CompilerUsedV; | |
2759 | ||
2760 | public: | |
2761 | LLVMUsed(Module &M) { | |
2762 | UsedV = collectUsedGlobalVariables(M, Used, false); | |
2763 | CompilerUsedV = collectUsedGlobalVariables(M, CompilerUsed, true); | |
2764 | } | |
2765 | typedef SmallPtrSet<GlobalValue *, 8>::iterator iterator; | |
2766 | typedef iterator_range<iterator> used_iterator_range; | |
2767 | iterator usedBegin() { return Used.begin(); } | |
2768 | iterator usedEnd() { return Used.end(); } | |
2769 | used_iterator_range used() { | |
2770 | return used_iterator_range(usedBegin(), usedEnd()); | |
2771 | } | |
2772 | iterator compilerUsedBegin() { return CompilerUsed.begin(); } | |
2773 | iterator compilerUsedEnd() { return CompilerUsed.end(); } | |
2774 | used_iterator_range compilerUsed() { | |
2775 | return used_iterator_range(compilerUsedBegin(), compilerUsedEnd()); | |
2776 | } | |
2777 | bool usedCount(GlobalValue *GV) const { return Used.count(GV); } | |
2778 | bool compilerUsedCount(GlobalValue *GV) const { | |
2779 | return CompilerUsed.count(GV); | |
2780 | } | |
2781 | bool usedErase(GlobalValue *GV) { return Used.erase(GV); } | |
2782 | bool compilerUsedErase(GlobalValue *GV) { return CompilerUsed.erase(GV); } | |
85aaf69f SL |
2783 | bool usedInsert(GlobalValue *GV) { return Used.insert(GV).second; } |
2784 | bool compilerUsedInsert(GlobalValue *GV) { | |
2785 | return CompilerUsed.insert(GV).second; | |
2786 | } | |
1a4d82fc JJ |
2787 | |
2788 | void syncVariablesAndSets() { | |
2789 | if (UsedV) | |
2790 | setUsedInitializer(*UsedV, Used); | |
2791 | if (CompilerUsedV) | |
2792 | setUsedInitializer(*CompilerUsedV, CompilerUsed); | |
223e47cc | 2793 | } |
1a4d82fc JJ |
2794 | }; |
2795 | } | |
2796 | ||
2797 | static bool hasUseOtherThanLLVMUsed(GlobalAlias &GA, const LLVMUsed &U) { | |
2798 | if (GA.use_empty()) // No use at all. | |
2799 | return false; | |
2800 | ||
2801 | assert((!U.usedCount(&GA) || !U.compilerUsedCount(&GA)) && | |
2802 | "We should have removed the duplicated " | |
2803 | "element from llvm.compiler.used"); | |
2804 | if (!GA.hasOneUse()) | |
2805 | // Strictly more than one use. So at least one is not in llvm.used and | |
2806 | // llvm.compiler.used. | |
2807 | return true; | |
2808 | ||
2809 | // Exactly one use. Check if it is in llvm.used or llvm.compiler.used. | |
2810 | return !U.usedCount(&GA) && !U.compilerUsedCount(&GA); | |
2811 | } | |
2812 | ||
2813 | static bool hasMoreThanOneUseOtherThanLLVMUsed(GlobalValue &V, | |
2814 | const LLVMUsed &U) { | |
2815 | unsigned N = 2; | |
2816 | assert((!U.usedCount(&V) || !U.compilerUsedCount(&V)) && | |
2817 | "We should have removed the duplicated " | |
2818 | "element from llvm.compiler.used"); | |
2819 | if (U.usedCount(&V) || U.compilerUsedCount(&V)) | |
2820 | ++N; | |
2821 | return V.hasNUsesOrMore(N); | |
2822 | } | |
2823 | ||
2824 | static bool mayHaveOtherReferences(GlobalAlias &GA, const LLVMUsed &U) { | |
2825 | if (!GA.hasLocalLinkage()) | |
2826 | return true; | |
223e47cc | 2827 | |
1a4d82fc JJ |
2828 | return U.usedCount(&GA) || U.compilerUsedCount(&GA); |
2829 | } | |
223e47cc | 2830 | |
1a4d82fc JJ |
2831 | static bool hasUsesToReplace(GlobalAlias &GA, const LLVMUsed &U, |
2832 | bool &RenameTarget) { | |
2833 | RenameTarget = false; | |
2834 | bool Ret = false; | |
2835 | if (hasUseOtherThanLLVMUsed(GA, U)) | |
2836 | Ret = true; | |
2837 | ||
2838 | // If the alias is externally visible, we may still be able to simplify it. | |
2839 | if (!mayHaveOtherReferences(GA, U)) | |
2840 | return Ret; | |
2841 | ||
2842 | // If the aliasee has internal linkage, give it the name and linkage | |
2843 | // of the alias, and delete the alias. This turns: | |
2844 | // define internal ... @f(...) | |
2845 | // @a = alias ... @f | |
2846 | // into: | |
2847 | // define ... @a(...) | |
2848 | Constant *Aliasee = GA.getAliasee(); | |
2849 | GlobalValue *Target = cast<GlobalValue>(Aliasee->stripPointerCasts()); | |
2850 | if (!Target->hasLocalLinkage()) | |
2851 | return Ret; | |
2852 | ||
2853 | // Do not perform the transform if multiple aliases potentially target the | |
2854 | // aliasee. This check also ensures that it is safe to replace the section | |
2855 | // and other attributes of the aliasee with those of the alias. | |
2856 | if (hasMoreThanOneUseOtherThanLLVMUsed(*Target, U)) | |
2857 | return Ret; | |
2858 | ||
2859 | RenameTarget = true; | |
223e47cc LB |
2860 | return true; |
2861 | } | |
2862 | ||
2863 | bool GlobalOpt::OptimizeGlobalAliases(Module &M) { | |
2864 | bool Changed = false; | |
1a4d82fc JJ |
2865 | LLVMUsed Used(M); |
2866 | ||
2867 | for (GlobalValue *GV : Used.used()) | |
2868 | Used.compilerUsedErase(GV); | |
223e47cc LB |
2869 | |
2870 | for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end(); | |
2871 | I != E;) { | |
2872 | Module::alias_iterator J = I++; | |
2873 | // Aliases without names cannot be referenced outside this module. | |
1a4d82fc | 2874 | if (!J->hasName() && !J->isDeclaration() && !J->hasLocalLinkage()) |
223e47cc LB |
2875 | J->setLinkage(GlobalValue::InternalLinkage); |
2876 | // If the aliasee may change at link time, nothing can be done - bail out. | |
2877 | if (J->mayBeOverridden()) | |
2878 | continue; | |
2879 | ||
2880 | Constant *Aliasee = J->getAliasee(); | |
1a4d82fc JJ |
2881 | GlobalValue *Target = dyn_cast<GlobalValue>(Aliasee->stripPointerCasts()); |
2882 | // We can't trivially replace the alias with the aliasee if the aliasee is | |
2883 | // non-trivial in some way. | |
2884 | // TODO: Try to handle non-zero GEPs of local aliasees. | |
2885 | if (!Target) | |
2886 | continue; | |
223e47cc | 2887 | Target->removeDeadConstantUsers(); |
223e47cc LB |
2888 | |
2889 | // Make all users of the alias use the aliasee instead. | |
1a4d82fc JJ |
2890 | bool RenameTarget; |
2891 | if (!hasUsesToReplace(*J, Used, RenameTarget)) | |
2892 | continue; | |
223e47cc | 2893 | |
1a4d82fc JJ |
2894 | J->replaceAllUsesWith(ConstantExpr::getBitCast(Aliasee, J->getType())); |
2895 | ++NumAliasesResolved; | |
2896 | Changed = true; | |
223e47cc | 2897 | |
1a4d82fc | 2898 | if (RenameTarget) { |
223e47cc LB |
2899 | // Give the aliasee the name, linkage and other attributes of the alias. |
2900 | Target->takeName(J); | |
2901 | Target->setLinkage(J->getLinkage()); | |
1a4d82fc JJ |
2902 | Target->setVisibility(J->getVisibility()); |
2903 | Target->setDLLStorageClass(J->getDLLStorageClass()); | |
2904 | ||
2905 | if (Used.usedErase(J)) | |
2906 | Used.usedInsert(Target); | |
2907 | ||
2908 | if (Used.compilerUsedErase(J)) | |
2909 | Used.compilerUsedInsert(Target); | |
2910 | } else if (mayHaveOtherReferences(*J, Used)) | |
2911 | continue; | |
223e47cc LB |
2912 | |
2913 | // Delete the alias. | |
2914 | M.getAliasList().erase(J); | |
2915 | ++NumAliasesRemoved; | |
2916 | Changed = true; | |
2917 | } | |
2918 | ||
1a4d82fc JJ |
2919 | Used.syncVariablesAndSets(); |
2920 | ||
223e47cc LB |
2921 | return Changed; |
2922 | } | |
2923 | ||
2924 | static Function *FindCXAAtExit(Module &M, TargetLibraryInfo *TLI) { | |
2925 | if (!TLI->has(LibFunc::cxa_atexit)) | |
1a4d82fc | 2926 | return nullptr; |
223e47cc LB |
2927 | |
2928 | Function *Fn = M.getFunction(TLI->getName(LibFunc::cxa_atexit)); | |
970d7e83 | 2929 | |
223e47cc | 2930 | if (!Fn) |
1a4d82fc | 2931 | return nullptr; |
223e47cc LB |
2932 | |
2933 | FunctionType *FTy = Fn->getFunctionType(); | |
970d7e83 LB |
2934 | |
2935 | // Checking that the function has the right return type, the right number of | |
223e47cc LB |
2936 | // parameters and that they all have pointer types should be enough. |
2937 | if (!FTy->getReturnType()->isIntegerTy() || | |
2938 | FTy->getNumParams() != 3 || | |
2939 | !FTy->getParamType(0)->isPointerTy() || | |
2940 | !FTy->getParamType(1)->isPointerTy() || | |
2941 | !FTy->getParamType(2)->isPointerTy()) | |
1a4d82fc | 2942 | return nullptr; |
223e47cc LB |
2943 | |
2944 | return Fn; | |
2945 | } | |
2946 | ||
2947 | /// cxxDtorIsEmpty - Returns whether the given function is an empty C++ | |
2948 | /// destructor and can therefore be eliminated. | |
2949 | /// Note that we assume that other optimization passes have already simplified | |
2950 | /// the code so we only look for a function with a single basic block, where | |
2951 | /// the only allowed instructions are 'ret', 'call' to an empty C++ dtor and | |
2952 | /// other side-effect free instructions. | |
2953 | static bool cxxDtorIsEmpty(const Function &Fn, | |
2954 | SmallPtrSet<const Function *, 8> &CalledFunctions) { | |
2955 | // FIXME: We could eliminate C++ destructors if they're readonly/readnone and | |
2956 | // nounwind, but that doesn't seem worth doing. | |
2957 | if (Fn.isDeclaration()) | |
2958 | return false; | |
2959 | ||
2960 | if (++Fn.begin() != Fn.end()) | |
2961 | return false; | |
2962 | ||
2963 | const BasicBlock &EntryBlock = Fn.getEntryBlock(); | |
2964 | for (BasicBlock::const_iterator I = EntryBlock.begin(), E = EntryBlock.end(); | |
2965 | I != E; ++I) { | |
2966 | if (const CallInst *CI = dyn_cast<CallInst>(I)) { | |
2967 | // Ignore debug intrinsics. | |
2968 | if (isa<DbgInfoIntrinsic>(CI)) | |
2969 | continue; | |
2970 | ||
2971 | const Function *CalledFn = CI->getCalledFunction(); | |
2972 | ||
2973 | if (!CalledFn) | |
2974 | return false; | |
2975 | ||
2976 | SmallPtrSet<const Function *, 8> NewCalledFunctions(CalledFunctions); | |
2977 | ||
2978 | // Don't treat recursive functions as empty. | |
85aaf69f | 2979 | if (!NewCalledFunctions.insert(CalledFn).second) |
223e47cc LB |
2980 | return false; |
2981 | ||
2982 | if (!cxxDtorIsEmpty(*CalledFn, NewCalledFunctions)) | |
2983 | return false; | |
2984 | } else if (isa<ReturnInst>(*I)) | |
2985 | return true; // We're done. | |
2986 | else if (I->mayHaveSideEffects()) | |
2987 | return false; // Destructor with side effects, bail. | |
2988 | } | |
2989 | ||
2990 | return false; | |
2991 | } | |
2992 | ||
2993 | bool GlobalOpt::OptimizeEmptyGlobalCXXDtors(Function *CXAAtExitFn) { | |
2994 | /// Itanium C++ ABI p3.3.5: | |
2995 | /// | |
2996 | /// After constructing a global (or local static) object, that will require | |
2997 | /// destruction on exit, a termination function is registered as follows: | |
2998 | /// | |
2999 | /// extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d ); | |
3000 | /// | |
3001 | /// This registration, e.g. __cxa_atexit(f,p,d), is intended to cause the | |
3002 | /// call f(p) when DSO d is unloaded, before all such termination calls | |
3003 | /// registered before this one. It returns zero if registration is | |
3004 | /// successful, nonzero on failure. | |
3005 | ||
3006 | // This pass will look for calls to __cxa_atexit where the function is trivial | |
3007 | // and remove them. | |
3008 | bool Changed = false; | |
3009 | ||
1a4d82fc JJ |
3010 | for (auto I = CXAAtExitFn->user_begin(), E = CXAAtExitFn->user_end(); |
3011 | I != E;) { | |
223e47cc LB |
3012 | // We're only interested in calls. Theoretically, we could handle invoke |
3013 | // instructions as well, but neither llvm-gcc nor clang generate invokes | |
3014 | // to __cxa_atexit. | |
3015 | CallInst *CI = dyn_cast<CallInst>(*I++); | |
3016 | if (!CI) | |
3017 | continue; | |
3018 | ||
970d7e83 | 3019 | Function *DtorFn = |
223e47cc LB |
3020 | dyn_cast<Function>(CI->getArgOperand(0)->stripPointerCasts()); |
3021 | if (!DtorFn) | |
3022 | continue; | |
3023 | ||
3024 | SmallPtrSet<const Function *, 8> CalledFunctions; | |
3025 | if (!cxxDtorIsEmpty(*DtorFn, CalledFunctions)) | |
3026 | continue; | |
3027 | ||
3028 | // Just remove the call. | |
3029 | CI->replaceAllUsesWith(Constant::getNullValue(CI->getType())); | |
3030 | CI->eraseFromParent(); | |
3031 | ||
3032 | ++NumCXXDtorsRemoved; | |
3033 | ||
3034 | Changed |= true; | |
3035 | } | |
3036 | ||
3037 | return Changed; | |
3038 | } | |
3039 | ||
3040 | bool GlobalOpt::runOnModule(Module &M) { | |
3041 | bool Changed = false; | |
3042 | ||
1a4d82fc JJ |
3043 | DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); |
3044 | DL = DLP ? &DLP->getDataLayout() : nullptr; | |
223e47cc LB |
3045 | TLI = &getAnalysis<TargetLibraryInfo>(); |
3046 | ||
223e47cc LB |
3047 | bool LocalChange = true; |
3048 | while (LocalChange) { | |
3049 | LocalChange = false; | |
3050 | ||
85aaf69f SL |
3051 | NotDiscardableComdats.clear(); |
3052 | for (const GlobalVariable &GV : M.globals()) | |
3053 | if (const Comdat *C = GV.getComdat()) | |
3054 | if (!GV.isDiscardableIfUnused() || !GV.use_empty()) | |
3055 | NotDiscardableComdats.insert(C); | |
3056 | for (Function &F : M) | |
3057 | if (const Comdat *C = F.getComdat()) | |
3058 | if (!F.isDefTriviallyDead()) | |
3059 | NotDiscardableComdats.insert(C); | |
3060 | for (GlobalAlias &GA : M.aliases()) | |
3061 | if (const Comdat *C = GA.getComdat()) | |
3062 | if (!GA.isDiscardableIfUnused() || !GA.use_empty()) | |
3063 | NotDiscardableComdats.insert(C); | |
3064 | ||
223e47cc LB |
3065 | // Delete functions that are trivially dead, ccc -> fastcc |
3066 | LocalChange |= OptimizeFunctions(M); | |
3067 | ||
3068 | // Optimize global_ctors list. | |
1a4d82fc JJ |
3069 | LocalChange |= optimizeGlobalCtorsList(M, [&](Function *F) { |
3070 | return EvaluateStaticConstructor(F, DL, TLI); | |
3071 | }); | |
223e47cc LB |
3072 | |
3073 | // Optimize non-address-taken globals. | |
3074 | LocalChange |= OptimizeGlobalVars(M); | |
3075 | ||
3076 | // Resolve aliases, when possible. | |
3077 | LocalChange |= OptimizeGlobalAliases(M); | |
3078 | ||
1a4d82fc JJ |
3079 | // Try to remove trivial global destructors if they are not removed |
3080 | // already. | |
3081 | Function *CXAAtExitFn = FindCXAAtExit(M, TLI); | |
223e47cc LB |
3082 | if (CXAAtExitFn) |
3083 | LocalChange |= OptimizeEmptyGlobalCXXDtors(CXAAtExitFn); | |
3084 | ||
3085 | Changed |= LocalChange; | |
3086 | } | |
3087 | ||
3088 | // TODO: Move all global ctors functions to the end of the module for code | |
3089 | // layout. | |
3090 | ||
3091 | return Changed; | |
3092 | } |