| File: | build/llvm-toolchain-snapshot-15~++20220420111733+e13d2efed663/llvm/include/llvm/Analysis/ValueLattice.h |
| Warning: | line 260, column 5 Undefined or garbage value returned to caller |
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| 1 | //===- LazyValueInfo.cpp - Value constraint analysis ------------*- C++ -*-===// | |||
| 2 | // | |||
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |||
| 4 | // See https://llvm.org/LICENSE.txt for license information. | |||
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |||
| 6 | // | |||
| 7 | //===----------------------------------------------------------------------===// | |||
| 8 | // | |||
| 9 | // This file defines the interface for lazy computation of value constraint | |||
| 10 | // information. | |||
| 11 | // | |||
| 12 | //===----------------------------------------------------------------------===// | |||
| 13 | ||||
| 14 | #include "llvm/Analysis/LazyValueInfo.h" | |||
| 15 | #include "llvm/ADT/DenseSet.h" | |||
| 16 | #include "llvm/ADT/Optional.h" | |||
| 17 | #include "llvm/ADT/STLExtras.h" | |||
| 18 | #include "llvm/Analysis/AssumptionCache.h" | |||
| 19 | #include "llvm/Analysis/ConstantFolding.h" | |||
| 20 | #include "llvm/Analysis/InstructionSimplify.h" | |||
| 21 | #include "llvm/Analysis/TargetLibraryInfo.h" | |||
| 22 | #include "llvm/Analysis/ValueLattice.h" | |||
| 23 | #include "llvm/Analysis/ValueTracking.h" | |||
| 24 | #include "llvm/IR/AssemblyAnnotationWriter.h" | |||
| 25 | #include "llvm/IR/CFG.h" | |||
| 26 | #include "llvm/IR/ConstantRange.h" | |||
| 27 | #include "llvm/IR/Constants.h" | |||
| 28 | #include "llvm/IR/DataLayout.h" | |||
| 29 | #include "llvm/IR/Dominators.h" | |||
| 30 | #include "llvm/IR/Instructions.h" | |||
| 31 | #include "llvm/IR/IntrinsicInst.h" | |||
| 32 | #include "llvm/IR/Intrinsics.h" | |||
| 33 | #include "llvm/IR/LLVMContext.h" | |||
| 34 | #include "llvm/IR/PatternMatch.h" | |||
| 35 | #include "llvm/IR/ValueHandle.h" | |||
| 36 | #include "llvm/InitializePasses.h" | |||
| 37 | #include "llvm/Support/Debug.h" | |||
| 38 | #include "llvm/Support/FormattedStream.h" | |||
| 39 | #include "llvm/Support/KnownBits.h" | |||
| 40 | #include "llvm/Support/raw_ostream.h" | |||
| 41 | using namespace llvm; | |||
| 42 | using namespace PatternMatch; | |||
| 43 | ||||
| 44 | #define DEBUG_TYPE"lazy-value-info" "lazy-value-info" | |||
| 45 | ||||
| 46 | // This is the number of worklist items we will process to try to discover an | |||
| 47 | // answer for a given value. | |||
| 48 | static const unsigned MaxProcessedPerValue = 500; | |||
| 49 | ||||
| 50 | char LazyValueInfoWrapperPass::ID = 0; | |||
| 51 | LazyValueInfoWrapperPass::LazyValueInfoWrapperPass() : FunctionPass(ID) { | |||
| 52 | initializeLazyValueInfoWrapperPassPass(*PassRegistry::getPassRegistry()); | |||
| 53 | } | |||
| 54 | INITIALIZE_PASS_BEGIN(LazyValueInfoWrapperPass, "lazy-value-info",static void *initializeLazyValueInfoWrapperPassPassOnce(PassRegistry &Registry) { | |||
| 55 | "Lazy Value Information Analysis", false, true)static void *initializeLazyValueInfoWrapperPassPassOnce(PassRegistry &Registry) { | |||
| 56 | INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry); | |||
| 57 | INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry); | |||
| 58 | INITIALIZE_PASS_END(LazyValueInfoWrapperPass, "lazy-value-info",PassInfo *PI = new PassInfo( "Lazy Value Information Analysis" , "lazy-value-info", &LazyValueInfoWrapperPass::ID, PassInfo ::NormalCtor_t(callDefaultCtor<LazyValueInfoWrapperPass> ), false, true); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeLazyValueInfoWrapperPassPassFlag ; void llvm::initializeLazyValueInfoWrapperPassPass(PassRegistry &Registry) { llvm::call_once(InitializeLazyValueInfoWrapperPassPassFlag , initializeLazyValueInfoWrapperPassPassOnce, std::ref(Registry )); } | |||
| 59 | "Lazy Value Information Analysis", false, true)PassInfo *PI = new PassInfo( "Lazy Value Information Analysis" , "lazy-value-info", &LazyValueInfoWrapperPass::ID, PassInfo ::NormalCtor_t(callDefaultCtor<LazyValueInfoWrapperPass> ), false, true); Registry.registerPass(*PI, true); return PI; } static llvm::once_flag InitializeLazyValueInfoWrapperPassPassFlag ; void llvm::initializeLazyValueInfoWrapperPassPass(PassRegistry &Registry) { llvm::call_once(InitializeLazyValueInfoWrapperPassPassFlag , initializeLazyValueInfoWrapperPassPassOnce, std::ref(Registry )); } | |||
| 60 | ||||
| 61 | namespace llvm { | |||
| 62 | FunctionPass *createLazyValueInfoPass() { return new LazyValueInfoWrapperPass(); } | |||
| 63 | } | |||
| 64 | ||||
| 65 | AnalysisKey LazyValueAnalysis::Key; | |||
| 66 | ||||
| 67 | /// Returns true if this lattice value represents at most one possible value. | |||
| 68 | /// This is as precise as any lattice value can get while still representing | |||
| 69 | /// reachable code. | |||
| 70 | static bool hasSingleValue(const ValueLatticeElement &Val) { | |||
| 71 | if (Val.isConstantRange() && | |||
| 72 | Val.getConstantRange().isSingleElement()) | |||
| 73 | // Integer constants are single element ranges | |||
| 74 | return true; | |||
| 75 | if (Val.isConstant()) | |||
| 76 | // Non integer constants | |||
| 77 | return true; | |||
| 78 | return false; | |||
| 79 | } | |||
| 80 | ||||
| 81 | /// Combine two sets of facts about the same value into a single set of | |||
| 82 | /// facts. Note that this method is not suitable for merging facts along | |||
| 83 | /// different paths in a CFG; that's what the mergeIn function is for. This | |||
| 84 | /// is for merging facts gathered about the same value at the same location | |||
| 85 | /// through two independent means. | |||
| 86 | /// Notes: | |||
| 87 | /// * This method does not promise to return the most precise possible lattice | |||
| 88 | /// value implied by A and B. It is allowed to return any lattice element | |||
| 89 | /// which is at least as strong as *either* A or B (unless our facts | |||
| 90 | /// conflict, see below). | |||
| 91 | /// * Due to unreachable code, the intersection of two lattice values could be | |||
| 92 | /// contradictory. If this happens, we return some valid lattice value so as | |||
| 93 | /// not confuse the rest of LVI. Ideally, we'd always return Undefined, but | |||
| 94 | /// we do not make this guarantee. TODO: This would be a useful enhancement. | |||
| 95 | static ValueLatticeElement intersect(const ValueLatticeElement &A, | |||
| 96 | const ValueLatticeElement &B) { | |||
| 97 | // Undefined is the strongest state. It means the value is known to be along | |||
| 98 | // an unreachable path. | |||
| 99 | if (A.isUnknown()) | |||
| 100 | return A; | |||
| 101 | if (B.isUnknown()) | |||
| 102 | return B; | |||
| 103 | ||||
| 104 | // If we gave up for one, but got a useable fact from the other, use it. | |||
| 105 | if (A.isOverdefined()) | |||
| 106 | return B; | |||
| 107 | if (B.isOverdefined()) | |||
| 108 | return A; | |||
| 109 | ||||
| 110 | // Can't get any more precise than constants. | |||
| 111 | if (hasSingleValue(A)) | |||
| 112 | return A; | |||
| 113 | if (hasSingleValue(B)) | |||
| 114 | return B; | |||
| 115 | ||||
| 116 | // Could be either constant range or not constant here. | |||
| 117 | if (!A.isConstantRange() || !B.isConstantRange()) { | |||
| 118 | // TODO: Arbitrary choice, could be improved | |||
| 119 | return A; | |||
| 120 | } | |||
| 121 | ||||
| 122 | // Intersect two constant ranges | |||
| 123 | ConstantRange Range = | |||
| 124 | A.getConstantRange().intersectWith(B.getConstantRange()); | |||
| 125 | // Note: An empty range is implicitly converted to unknown or undef depending | |||
| 126 | // on MayIncludeUndef internally. | |||
| 127 | return ValueLatticeElement::getRange( | |||
| 128 | std::move(Range), /*MayIncludeUndef=*/A.isConstantRangeIncludingUndef() || | |||
| 129 | B.isConstantRangeIncludingUndef()); | |||
| 130 | } | |||
| 131 | ||||
| 132 | //===----------------------------------------------------------------------===// | |||
| 133 | // LazyValueInfoCache Decl | |||
| 134 | //===----------------------------------------------------------------------===// | |||
| 135 | ||||
| 136 | namespace { | |||
| 137 | /// A callback value handle updates the cache when values are erased. | |||
| 138 | class LazyValueInfoCache; | |||
| 139 | struct LVIValueHandle final : public CallbackVH { | |||
| 140 | LazyValueInfoCache *Parent; | |||
| 141 | ||||
| 142 | LVIValueHandle(Value *V, LazyValueInfoCache *P = nullptr) | |||
| 143 | : CallbackVH(V), Parent(P) { } | |||
| 144 | ||||
| 145 | void deleted() override; | |||
| 146 | void allUsesReplacedWith(Value *V) override { | |||
| 147 | deleted(); | |||
| 148 | } | |||
| 149 | }; | |||
| 150 | } // end anonymous namespace | |||
| 151 | ||||
| 152 | namespace { | |||
| 153 | using NonNullPointerSet = SmallDenseSet<AssertingVH<Value>, 2>; | |||
| 154 | ||||
| 155 | /// This is the cache kept by LazyValueInfo which | |||
| 156 | /// maintains information about queries across the clients' queries. | |||
| 157 | class LazyValueInfoCache { | |||
| 158 | /// This is all of the cached information for one basic block. It contains | |||
| 159 | /// the per-value lattice elements, as well as a separate set for | |||
| 160 | /// overdefined values to reduce memory usage. Additionally pointers | |||
| 161 | /// dereferenced in the block are cached for nullability queries. | |||
| 162 | struct BlockCacheEntry { | |||
| 163 | SmallDenseMap<AssertingVH<Value>, ValueLatticeElement, 4> LatticeElements; | |||
| 164 | SmallDenseSet<AssertingVH<Value>, 4> OverDefined; | |||
| 165 | // None indicates that the nonnull pointers for this basic block | |||
| 166 | // block have not been computed yet. | |||
| 167 | Optional<NonNullPointerSet> NonNullPointers; | |||
| 168 | }; | |||
| 169 | ||||
| 170 | /// Cached information per basic block. | |||
| 171 | DenseMap<PoisoningVH<BasicBlock>, std::unique_ptr<BlockCacheEntry>> | |||
| 172 | BlockCache; | |||
| 173 | /// Set of value handles used to erase values from the cache on deletion. | |||
| 174 | DenseSet<LVIValueHandle, DenseMapInfo<Value *>> ValueHandles; | |||
| 175 | ||||
| 176 | const BlockCacheEntry *getBlockEntry(BasicBlock *BB) const { | |||
| 177 | auto It = BlockCache.find_as(BB); | |||
| 178 | if (It == BlockCache.end()) | |||
| 179 | return nullptr; | |||
| 180 | return It->second.get(); | |||
| 181 | } | |||
| 182 | ||||
| 183 | BlockCacheEntry *getOrCreateBlockEntry(BasicBlock *BB) { | |||
| 184 | auto It = BlockCache.find_as(BB); | |||
| 185 | if (It == BlockCache.end()) | |||
| 186 | It = BlockCache.insert({ BB, std::make_unique<BlockCacheEntry>() }) | |||
| 187 | .first; | |||
| 188 | ||||
| 189 | return It->second.get(); | |||
| 190 | } | |||
| 191 | ||||
| 192 | void addValueHandle(Value *Val) { | |||
| 193 | auto HandleIt = ValueHandles.find_as(Val); | |||
| 194 | if (HandleIt == ValueHandles.end()) | |||
| 195 | ValueHandles.insert({ Val, this }); | |||
| 196 | } | |||
| 197 | ||||
| 198 | public: | |||
| 199 | void insertResult(Value *Val, BasicBlock *BB, | |||
| 200 | const ValueLatticeElement &Result) { | |||
| 201 | BlockCacheEntry *Entry = getOrCreateBlockEntry(BB); | |||
| 202 | ||||
| 203 | // Insert over-defined values into their own cache to reduce memory | |||
| 204 | // overhead. | |||
| 205 | if (Result.isOverdefined()) | |||
| 206 | Entry->OverDefined.insert(Val); | |||
| 207 | else | |||
| 208 | Entry->LatticeElements.insert({ Val, Result }); | |||
| 209 | ||||
| 210 | addValueHandle(Val); | |||
| 211 | } | |||
| 212 | ||||
| 213 | Optional<ValueLatticeElement> getCachedValueInfo(Value *V, | |||
| 214 | BasicBlock *BB) const { | |||
| 215 | const BlockCacheEntry *Entry = getBlockEntry(BB); | |||
| 216 | if (!Entry) | |||
| 217 | return None; | |||
| 218 | ||||
| 219 | if (Entry->OverDefined.count(V)) | |||
| 220 | return ValueLatticeElement::getOverdefined(); | |||
| 221 | ||||
| 222 | auto LatticeIt = Entry->LatticeElements.find_as(V); | |||
| 223 | if (LatticeIt == Entry->LatticeElements.end()) | |||
| 224 | return None; | |||
| 225 | ||||
| 226 | return LatticeIt->second; | |||
| 227 | } | |||
| 228 | ||||
| 229 | bool isNonNullAtEndOfBlock( | |||
| 230 | Value *V, BasicBlock *BB, | |||
| 231 | function_ref<NonNullPointerSet(BasicBlock *)> InitFn) { | |||
| 232 | BlockCacheEntry *Entry = getOrCreateBlockEntry(BB); | |||
| 233 | if (!Entry->NonNullPointers) { | |||
| 234 | Entry->NonNullPointers = InitFn(BB); | |||
| 235 | for (Value *V : *Entry->NonNullPointers) | |||
| 236 | addValueHandle(V); | |||
| 237 | } | |||
| 238 | ||||
| 239 | return Entry->NonNullPointers->count(V); | |||
| 240 | } | |||
| 241 | ||||
| 242 | /// clear - Empty the cache. | |||
| 243 | void clear() { | |||
| 244 | BlockCache.clear(); | |||
| 245 | ValueHandles.clear(); | |||
| 246 | } | |||
| 247 | ||||
| 248 | /// Inform the cache that a given value has been deleted. | |||
| 249 | void eraseValue(Value *V); | |||
| 250 | ||||
| 251 | /// This is part of the update interface to inform the cache | |||
| 252 | /// that a block has been deleted. | |||
| 253 | void eraseBlock(BasicBlock *BB); | |||
| 254 | ||||
| 255 | /// Updates the cache to remove any influence an overdefined value in | |||
| 256 | /// OldSucc might have (unless also overdefined in NewSucc). This just | |||
| 257 | /// flushes elements from the cache and does not add any. | |||
| 258 | void threadEdgeImpl(BasicBlock *OldSucc,BasicBlock *NewSucc); | |||
| 259 | }; | |||
| 260 | } | |||
| 261 | ||||
| 262 | void LazyValueInfoCache::eraseValue(Value *V) { | |||
| 263 | for (auto &Pair : BlockCache) { | |||
| 264 | Pair.second->LatticeElements.erase(V); | |||
| 265 | Pair.second->OverDefined.erase(V); | |||
| 266 | if (Pair.second->NonNullPointers) | |||
| 267 | Pair.second->NonNullPointers->erase(V); | |||
| 268 | } | |||
| 269 | ||||
| 270 | auto HandleIt = ValueHandles.find_as(V); | |||
| 271 | if (HandleIt != ValueHandles.end()) | |||
| 272 | ValueHandles.erase(HandleIt); | |||
| 273 | } | |||
| 274 | ||||
| 275 | void LVIValueHandle::deleted() { | |||
| 276 | // This erasure deallocates *this, so it MUST happen after we're done | |||
| 277 | // using any and all members of *this. | |||
| 278 | Parent->eraseValue(*this); | |||
| 279 | } | |||
| 280 | ||||
| 281 | void LazyValueInfoCache::eraseBlock(BasicBlock *BB) { | |||
| 282 | BlockCache.erase(BB); | |||
| 283 | } | |||
| 284 | ||||
| 285 | void LazyValueInfoCache::threadEdgeImpl(BasicBlock *OldSucc, | |||
| 286 | BasicBlock *NewSucc) { | |||
| 287 | // When an edge in the graph has been threaded, values that we could not | |||
| 288 | // determine a value for before (i.e. were marked overdefined) may be | |||
| 289 | // possible to solve now. We do NOT try to proactively update these values. | |||
| 290 | // Instead, we clear their entries from the cache, and allow lazy updating to | |||
| 291 | // recompute them when needed. | |||
| 292 | ||||
| 293 | // The updating process is fairly simple: we need to drop cached info | |||
| 294 | // for all values that were marked overdefined in OldSucc, and for those same | |||
| 295 | // values in any successor of OldSucc (except NewSucc) in which they were | |||
| 296 | // also marked overdefined. | |||
| 297 | std::vector<BasicBlock*> worklist; | |||
| 298 | worklist.push_back(OldSucc); | |||
| 299 | ||||
| 300 | const BlockCacheEntry *Entry = getBlockEntry(OldSucc); | |||
| 301 | if (!Entry || Entry->OverDefined.empty()) | |||
| 302 | return; // Nothing to process here. | |||
| 303 | SmallVector<Value *, 4> ValsToClear(Entry->OverDefined.begin(), | |||
| 304 | Entry->OverDefined.end()); | |||
| 305 | ||||
| 306 | // Use a worklist to perform a depth-first search of OldSucc's successors. | |||
| 307 | // NOTE: We do not need a visited list since any blocks we have already | |||
| 308 | // visited will have had their overdefined markers cleared already, and we | |||
| 309 | // thus won't loop to their successors. | |||
| 310 | while (!worklist.empty()) { | |||
| 311 | BasicBlock *ToUpdate = worklist.back(); | |||
| 312 | worklist.pop_back(); | |||
| 313 | ||||
| 314 | // Skip blocks only accessible through NewSucc. | |||
| 315 | if (ToUpdate == NewSucc) continue; | |||
| 316 | ||||
| 317 | // If a value was marked overdefined in OldSucc, and is here too... | |||
| 318 | auto OI = BlockCache.find_as(ToUpdate); | |||
| 319 | if (OI == BlockCache.end() || OI->second->OverDefined.empty()) | |||
| 320 | continue; | |||
| 321 | auto &ValueSet = OI->second->OverDefined; | |||
| 322 | ||||
| 323 | bool changed = false; | |||
| 324 | for (Value *V : ValsToClear) { | |||
| 325 | if (!ValueSet.erase(V)) | |||
| 326 | continue; | |||
| 327 | ||||
| 328 | // If we removed anything, then we potentially need to update | |||
| 329 | // blocks successors too. | |||
| 330 | changed = true; | |||
| 331 | } | |||
| 332 | ||||
| 333 | if (!changed) continue; | |||
| 334 | ||||
| 335 | llvm::append_range(worklist, successors(ToUpdate)); | |||
| 336 | } | |||
| 337 | } | |||
| 338 | ||||
| 339 | ||||
| 340 | namespace { | |||
| 341 | /// An assembly annotator class to print LazyValueCache information in | |||
| 342 | /// comments. | |||
| 343 | class LazyValueInfoImpl; | |||
| 344 | class LazyValueInfoAnnotatedWriter : public AssemblyAnnotationWriter { | |||
| 345 | LazyValueInfoImpl *LVIImpl; | |||
| 346 | // While analyzing which blocks we can solve values for, we need the dominator | |||
| 347 | // information. | |||
| 348 | DominatorTree &DT; | |||
| 349 | ||||
| 350 | public: | |||
| 351 | LazyValueInfoAnnotatedWriter(LazyValueInfoImpl *L, DominatorTree &DTree) | |||
| 352 | : LVIImpl(L), DT(DTree) {} | |||
| 353 | ||||
| 354 | void emitBasicBlockStartAnnot(const BasicBlock *BB, | |||
| 355 | formatted_raw_ostream &OS) override; | |||
| 356 | ||||
| 357 | void emitInstructionAnnot(const Instruction *I, | |||
| 358 | formatted_raw_ostream &OS) override; | |||
| 359 | }; | |||
| 360 | } | |||
| 361 | namespace { | |||
| 362 | // The actual implementation of the lazy analysis and update. Note that the | |||
| 363 | // inheritance from LazyValueInfoCache is intended to be temporary while | |||
| 364 | // splitting the code and then transitioning to a has-a relationship. | |||
| 365 | class LazyValueInfoImpl { | |||
| 366 | ||||
| 367 | /// Cached results from previous queries | |||
| 368 | LazyValueInfoCache TheCache; | |||
| 369 | ||||
| 370 | /// This stack holds the state of the value solver during a query. | |||
| 371 | /// It basically emulates the callstack of the naive | |||
| 372 | /// recursive value lookup process. | |||
| 373 | SmallVector<std::pair<BasicBlock*, Value*>, 8> BlockValueStack; | |||
| 374 | ||||
| 375 | /// Keeps track of which block-value pairs are in BlockValueStack. | |||
| 376 | DenseSet<std::pair<BasicBlock*, Value*> > BlockValueSet; | |||
| 377 | ||||
| 378 | /// Push BV onto BlockValueStack unless it's already in there. | |||
| 379 | /// Returns true on success. | |||
| 380 | bool pushBlockValue(const std::pair<BasicBlock *, Value *> &BV) { | |||
| 381 | if (!BlockValueSet.insert(BV).second) | |||
| 382 | return false; // It's already in the stack. | |||
| 383 | ||||
| 384 | LLVM_DEBUG(dbgs() << "PUSH: " << *BV.second << " in "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "PUSH: " << *BV. second << " in " << BV.first->getName() << "\n"; } } while (false) | |||
| 385 | << BV.first->getName() << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "PUSH: " << *BV. second << " in " << BV.first->getName() << "\n"; } } while (false); | |||
| 386 | BlockValueStack.push_back(BV); | |||
| 387 | return true; | |||
| 388 | } | |||
| 389 | ||||
| 390 | AssumptionCache *AC; ///< A pointer to the cache of @llvm.assume calls. | |||
| 391 | const DataLayout &DL; ///< A mandatory DataLayout | |||
| 392 | ||||
| 393 | /// Declaration of the llvm.experimental.guard() intrinsic, | |||
| 394 | /// if it exists in the module. | |||
| 395 | Function *GuardDecl; | |||
| 396 | ||||
| 397 | Optional<ValueLatticeElement> getBlockValue(Value *Val, BasicBlock *BB, | |||
| 398 | Instruction *CxtI); | |||
| 399 | Optional<ValueLatticeElement> getEdgeValue(Value *V, BasicBlock *F, | |||
| 400 | BasicBlock *T, Instruction *CxtI = nullptr); | |||
| 401 | ||||
| 402 | // These methods process one work item and may add more. A false value | |||
| 403 | // returned means that the work item was not completely processed and must | |||
| 404 | // be revisited after going through the new items. | |||
| 405 | bool solveBlockValue(Value *Val, BasicBlock *BB); | |||
| 406 | Optional<ValueLatticeElement> solveBlockValueImpl(Value *Val, BasicBlock *BB); | |||
| 407 | Optional<ValueLatticeElement> solveBlockValueNonLocal(Value *Val, | |||
| 408 | BasicBlock *BB); | |||
| 409 | Optional<ValueLatticeElement> solveBlockValuePHINode(PHINode *PN, | |||
| 410 | BasicBlock *BB); | |||
| 411 | Optional<ValueLatticeElement> solveBlockValueSelect(SelectInst *S, | |||
| 412 | BasicBlock *BB); | |||
| 413 | Optional<ConstantRange> getRangeFor(Value *V, Instruction *CxtI, | |||
| 414 | BasicBlock *BB); | |||
| 415 | Optional<ValueLatticeElement> solveBlockValueBinaryOpImpl( | |||
| 416 | Instruction *I, BasicBlock *BB, | |||
| 417 | std::function<ConstantRange(const ConstantRange &, | |||
| 418 | const ConstantRange &)> OpFn); | |||
| 419 | Optional<ValueLatticeElement> solveBlockValueBinaryOp(BinaryOperator *BBI, | |||
| 420 | BasicBlock *BB); | |||
| 421 | Optional<ValueLatticeElement> solveBlockValueCast(CastInst *CI, | |||
| 422 | BasicBlock *BB); | |||
| 423 | Optional<ValueLatticeElement> solveBlockValueOverflowIntrinsic( | |||
| 424 | WithOverflowInst *WO, BasicBlock *BB); | |||
| 425 | Optional<ValueLatticeElement> solveBlockValueIntrinsic(IntrinsicInst *II, | |||
| 426 | BasicBlock *BB); | |||
| 427 | Optional<ValueLatticeElement> solveBlockValueExtractValue( | |||
| 428 | ExtractValueInst *EVI, BasicBlock *BB); | |||
| 429 | bool isNonNullAtEndOfBlock(Value *Val, BasicBlock *BB); | |||
| 430 | void intersectAssumeOrGuardBlockValueConstantRange(Value *Val, | |||
| 431 | ValueLatticeElement &BBLV, | |||
| 432 | Instruction *BBI); | |||
| 433 | ||||
| 434 | void solve(); | |||
| 435 | ||||
| 436 | public: | |||
| 437 | /// This is the query interface to determine the lattice value for the | |||
| 438 | /// specified Value* at the context instruction (if specified) or at the | |||
| 439 | /// start of the block. | |||
| 440 | ValueLatticeElement getValueInBlock(Value *V, BasicBlock *BB, | |||
| 441 | Instruction *CxtI = nullptr); | |||
| 442 | ||||
| 443 | /// This is the query interface to determine the lattice value for the | |||
| 444 | /// specified Value* at the specified instruction using only information | |||
| 445 | /// from assumes/guards and range metadata. Unlike getValueInBlock(), no | |||
| 446 | /// recursive query is performed. | |||
| 447 | ValueLatticeElement getValueAt(Value *V, Instruction *CxtI); | |||
| 448 | ||||
| 449 | /// This is the query interface to determine the lattice | |||
| 450 | /// value for the specified Value* that is true on the specified edge. | |||
| 451 | ValueLatticeElement getValueOnEdge(Value *V, BasicBlock *FromBB, | |||
| 452 | BasicBlock *ToBB, | |||
| 453 | Instruction *CxtI = nullptr); | |||
| 454 | ||||
| 455 | /// Complete flush all previously computed values | |||
| 456 | void clear() { | |||
| 457 | TheCache.clear(); | |||
| 458 | } | |||
| 459 | ||||
| 460 | /// Printing the LazyValueInfo Analysis. | |||
| 461 | void printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS) { | |||
| 462 | LazyValueInfoAnnotatedWriter Writer(this, DTree); | |||
| 463 | F.print(OS, &Writer); | |||
| 464 | } | |||
| 465 | ||||
| 466 | /// This is part of the update interface to inform the cache | |||
| 467 | /// that a block has been deleted. | |||
| 468 | void eraseBlock(BasicBlock *BB) { | |||
| 469 | TheCache.eraseBlock(BB); | |||
| 470 | } | |||
| 471 | ||||
| 472 | /// This is the update interface to inform the cache that an edge from | |||
| 473 | /// PredBB to OldSucc has been threaded to be from PredBB to NewSucc. | |||
| 474 | void threadEdge(BasicBlock *PredBB,BasicBlock *OldSucc,BasicBlock *NewSucc); | |||
| 475 | ||||
| 476 | LazyValueInfoImpl(AssumptionCache *AC, const DataLayout &DL, | |||
| 477 | Function *GuardDecl) | |||
| 478 | : AC(AC), DL(DL), GuardDecl(GuardDecl) {} | |||
| 479 | }; | |||
| 480 | } // end anonymous namespace | |||
| 481 | ||||
| 482 | ||||
| 483 | void LazyValueInfoImpl::solve() { | |||
| 484 | SmallVector<std::pair<BasicBlock *, Value *>, 8> StartingStack( | |||
| 485 | BlockValueStack.begin(), BlockValueStack.end()); | |||
| 486 | ||||
| 487 | unsigned processedCount = 0; | |||
| 488 | while (!BlockValueStack.empty()) { | |||
| 489 | processedCount++; | |||
| 490 | // Abort if we have to process too many values to get a result for this one. | |||
| 491 | // Because of the design of the overdefined cache currently being per-block | |||
| 492 | // to avoid naming-related issues (IE it wants to try to give different | |||
| 493 | // results for the same name in different blocks), overdefined results don't | |||
| 494 | // get cached globally, which in turn means we will often try to rediscover | |||
| 495 | // the same overdefined result again and again. Once something like | |||
| 496 | // PredicateInfo is used in LVI or CVP, we should be able to make the | |||
| 497 | // overdefined cache global, and remove this throttle. | |||
| 498 | if (processedCount > MaxProcessedPerValue) { | |||
| 499 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "Giving up on stack because we are getting too deep\n" ; } } while (false) | |||
| 500 | dbgs() << "Giving up on stack because we are getting too deep\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "Giving up on stack because we are getting too deep\n" ; } } while (false); | |||
| 501 | // Fill in the original values | |||
| 502 | while (!StartingStack.empty()) { | |||
| 503 | std::pair<BasicBlock *, Value *> &e = StartingStack.back(); | |||
| 504 | TheCache.insertResult(e.second, e.first, | |||
| 505 | ValueLatticeElement::getOverdefined()); | |||
| 506 | StartingStack.pop_back(); | |||
| 507 | } | |||
| 508 | BlockValueSet.clear(); | |||
| 509 | BlockValueStack.clear(); | |||
| 510 | return; | |||
| 511 | } | |||
| 512 | std::pair<BasicBlock *, Value *> e = BlockValueStack.back(); | |||
| 513 | assert(BlockValueSet.count(e) && "Stack value should be in BlockValueSet!")(static_cast <bool> (BlockValueSet.count(e) && "Stack value should be in BlockValueSet!" ) ? void (0) : __assert_fail ("BlockValueSet.count(e) && \"Stack value should be in BlockValueSet!\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 513, __extension__ __PRETTY_FUNCTION__ )); | |||
| 514 | ||||
| 515 | if (solveBlockValue(e.second, e.first)) { | |||
| 516 | // The work item was completely processed. | |||
| 517 | assert(BlockValueStack.back() == e && "Nothing should have been pushed!")(static_cast <bool> (BlockValueStack.back() == e && "Nothing should have been pushed!") ? void (0) : __assert_fail ("BlockValueStack.back() == e && \"Nothing should have been pushed!\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 517, __extension__ __PRETTY_FUNCTION__ )); | |||
| 518 | #ifndef NDEBUG | |||
| 519 | Optional<ValueLatticeElement> BBLV = | |||
| 520 | TheCache.getCachedValueInfo(e.second, e.first); | |||
| 521 | assert(BBLV && "Result should be in cache!")(static_cast <bool> (BBLV && "Result should be in cache!" ) ? void (0) : __assert_fail ("BBLV && \"Result should be in cache!\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 521, __extension__ __PRETTY_FUNCTION__ )); | |||
| 522 | LLVM_DEBUG(do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "POP " << *e.second << " in " << e.first->getName() << " = " << *BBLV << "\n"; } } while (false) | |||
| 523 | dbgs() << "POP " << *e.second << " in " << e.first->getName() << " = "do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "POP " << *e.second << " in " << e.first->getName() << " = " << *BBLV << "\n"; } } while (false) | |||
| 524 | << *BBLV << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "POP " << *e.second << " in " << e.first->getName() << " = " << *BBLV << "\n"; } } while (false); | |||
| 525 | #endif | |||
| 526 | ||||
| 527 | BlockValueStack.pop_back(); | |||
| 528 | BlockValueSet.erase(e); | |||
| 529 | } else { | |||
| 530 | // More work needs to be done before revisiting. | |||
| 531 | assert(BlockValueStack.back() != e && "Stack should have been pushed!")(static_cast <bool> (BlockValueStack.back() != e && "Stack should have been pushed!") ? void (0) : __assert_fail ("BlockValueStack.back() != e && \"Stack should have been pushed!\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 531, __extension__ __PRETTY_FUNCTION__ )); | |||
| 532 | } | |||
| 533 | } | |||
| 534 | } | |||
| 535 | ||||
| 536 | Optional<ValueLatticeElement> LazyValueInfoImpl::getBlockValue( | |||
| 537 | Value *Val, BasicBlock *BB, Instruction *CxtI) { | |||
| 538 | // If already a constant, there is nothing to compute. | |||
| 539 | if (Constant *VC = dyn_cast<Constant>(Val)) | |||
| 540 | return ValueLatticeElement::get(VC); | |||
| 541 | ||||
| 542 | if (Optional<ValueLatticeElement> OptLatticeVal = | |||
| 543 | TheCache.getCachedValueInfo(Val, BB)) { | |||
| 544 | intersectAssumeOrGuardBlockValueConstantRange(Val, *OptLatticeVal, CxtI); | |||
| 545 | return OptLatticeVal; | |||
| 546 | } | |||
| 547 | ||||
| 548 | // We have hit a cycle, assume overdefined. | |||
| 549 | if (!pushBlockValue({ BB, Val })) | |||
| 550 | return ValueLatticeElement::getOverdefined(); | |||
| 551 | ||||
| 552 | // Yet to be resolved. | |||
| 553 | return None; | |||
| 554 | } | |||
| 555 | ||||
| 556 | static ValueLatticeElement getFromRangeMetadata(Instruction *BBI) { | |||
| 557 | switch (BBI->getOpcode()) { | |||
| 558 | default: break; | |||
| 559 | case Instruction::Load: | |||
| 560 | case Instruction::Call: | |||
| 561 | case Instruction::Invoke: | |||
| 562 | if (MDNode *Ranges = BBI->getMetadata(LLVMContext::MD_range)) | |||
| 563 | if (isa<IntegerType>(BBI->getType())) { | |||
| 564 | return ValueLatticeElement::getRange( | |||
| 565 | getConstantRangeFromMetadata(*Ranges)); | |||
| 566 | } | |||
| 567 | break; | |||
| 568 | }; | |||
| 569 | // Nothing known - will be intersected with other facts | |||
| 570 | return ValueLatticeElement::getOverdefined(); | |||
| 571 | } | |||
| 572 | ||||
| 573 | bool LazyValueInfoImpl::solveBlockValue(Value *Val, BasicBlock *BB) { | |||
| 574 | assert(!isa<Constant>(Val) && "Value should not be constant")(static_cast <bool> (!isa<Constant>(Val) && "Value should not be constant") ? void (0) : __assert_fail ( "!isa<Constant>(Val) && \"Value should not be constant\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 574, __extension__ __PRETTY_FUNCTION__ )); | |||
| 575 | assert(!TheCache.getCachedValueInfo(Val, BB) &&(static_cast <bool> (!TheCache.getCachedValueInfo(Val, BB ) && "Value should not be in cache") ? void (0) : __assert_fail ("!TheCache.getCachedValueInfo(Val, BB) && \"Value should not be in cache\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 576, __extension__ __PRETTY_FUNCTION__ )) | |||
| 576 | "Value should not be in cache")(static_cast <bool> (!TheCache.getCachedValueInfo(Val, BB ) && "Value should not be in cache") ? void (0) : __assert_fail ("!TheCache.getCachedValueInfo(Val, BB) && \"Value should not be in cache\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 576, __extension__ __PRETTY_FUNCTION__ )); | |||
| 577 | ||||
| 578 | // Hold off inserting this value into the Cache in case we have to return | |||
| 579 | // false and come back later. | |||
| 580 | Optional<ValueLatticeElement> Res = solveBlockValueImpl(Val, BB); | |||
| 581 | if (!Res) | |||
| 582 | // Work pushed, will revisit | |||
| 583 | return false; | |||
| 584 | ||||
| 585 | TheCache.insertResult(Val, BB, *Res); | |||
| 586 | return true; | |||
| 587 | } | |||
| 588 | ||||
| 589 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueImpl( | |||
| 590 | Value *Val, BasicBlock *BB) { | |||
| 591 | Instruction *BBI = dyn_cast<Instruction>(Val); | |||
| 592 | if (!BBI || BBI->getParent() != BB) | |||
| 593 | return solveBlockValueNonLocal(Val, BB); | |||
| 594 | ||||
| 595 | if (PHINode *PN = dyn_cast<PHINode>(BBI)) | |||
| 596 | return solveBlockValuePHINode(PN, BB); | |||
| 597 | ||||
| 598 | if (auto *SI = dyn_cast<SelectInst>(BBI)) | |||
| 599 | return solveBlockValueSelect(SI, BB); | |||
| 600 | ||||
| 601 | // If this value is a nonnull pointer, record it's range and bailout. Note | |||
| 602 | // that for all other pointer typed values, we terminate the search at the | |||
| 603 | // definition. We could easily extend this to look through geps, bitcasts, | |||
| 604 | // and the like to prove non-nullness, but it's not clear that's worth it | |||
| 605 | // compile time wise. The context-insensitive value walk done inside | |||
| 606 | // isKnownNonZero gets most of the profitable cases at much less expense. | |||
| 607 | // This does mean that we have a sensitivity to where the defining | |||
| 608 | // instruction is placed, even if it could legally be hoisted much higher. | |||
| 609 | // That is unfortunate. | |||
| 610 | PointerType *PT = dyn_cast<PointerType>(BBI->getType()); | |||
| 611 | if (PT && isKnownNonZero(BBI, DL)) | |||
| 612 | return ValueLatticeElement::getNot(ConstantPointerNull::get(PT)); | |||
| 613 | ||||
| 614 | if (BBI->getType()->isIntegerTy()) { | |||
| 615 | if (auto *CI = dyn_cast<CastInst>(BBI)) | |||
| 616 | return solveBlockValueCast(CI, BB); | |||
| 617 | ||||
| 618 | if (BinaryOperator *BO = dyn_cast<BinaryOperator>(BBI)) | |||
| 619 | return solveBlockValueBinaryOp(BO, BB); | |||
| 620 | ||||
| 621 | if (auto *EVI = dyn_cast<ExtractValueInst>(BBI)) | |||
| 622 | return solveBlockValueExtractValue(EVI, BB); | |||
| 623 | ||||
| 624 | if (auto *II = dyn_cast<IntrinsicInst>(BBI)) | |||
| 625 | return solveBlockValueIntrinsic(II, BB); | |||
| 626 | } | |||
| 627 | ||||
| 628 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - unknown inst def found.\n"; } } while (false) | |||
| 629 | << "' - unknown inst def found.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - unknown inst def found.\n"; } } while (false); | |||
| 630 | return getFromRangeMetadata(BBI); | |||
| 631 | } | |||
| 632 | ||||
| 633 | static void AddNonNullPointer(Value *Ptr, NonNullPointerSet &PtrSet) { | |||
| 634 | // TODO: Use NullPointerIsDefined instead. | |||
| 635 | if (Ptr->getType()->getPointerAddressSpace() == 0) | |||
| 636 | PtrSet.insert(getUnderlyingObject(Ptr)); | |||
| 637 | } | |||
| 638 | ||||
| 639 | static void AddNonNullPointersByInstruction( | |||
| 640 | Instruction *I, NonNullPointerSet &PtrSet) { | |||
| 641 | if (LoadInst *L = dyn_cast<LoadInst>(I)) { | |||
| 642 | AddNonNullPointer(L->getPointerOperand(), PtrSet); | |||
| 643 | } else if (StoreInst *S = dyn_cast<StoreInst>(I)) { | |||
| 644 | AddNonNullPointer(S->getPointerOperand(), PtrSet); | |||
| 645 | } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) { | |||
| 646 | if (MI->isVolatile()) return; | |||
| 647 | ||||
| 648 | // FIXME: check whether it has a valuerange that excludes zero? | |||
| 649 | ConstantInt *Len = dyn_cast<ConstantInt>(MI->getLength()); | |||
| 650 | if (!Len || Len->isZero()) return; | |||
| 651 | ||||
| 652 | AddNonNullPointer(MI->getRawDest(), PtrSet); | |||
| 653 | if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(MI)) | |||
| 654 | AddNonNullPointer(MTI->getRawSource(), PtrSet); | |||
| 655 | } | |||
| 656 | } | |||
| 657 | ||||
| 658 | bool LazyValueInfoImpl::isNonNullAtEndOfBlock(Value *Val, BasicBlock *BB) { | |||
| 659 | if (NullPointerIsDefined(BB->getParent(), | |||
| 660 | Val->getType()->getPointerAddressSpace())) | |||
| 661 | return false; | |||
| 662 | ||||
| 663 | Val = Val->stripInBoundsOffsets(); | |||
| 664 | return TheCache.isNonNullAtEndOfBlock(Val, BB, [](BasicBlock *BB) { | |||
| 665 | NonNullPointerSet NonNullPointers; | |||
| 666 | for (Instruction &I : *BB) | |||
| 667 | AddNonNullPointersByInstruction(&I, NonNullPointers); | |||
| 668 | return NonNullPointers; | |||
| 669 | }); | |||
| 670 | } | |||
| 671 | ||||
| 672 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueNonLocal( | |||
| 673 | Value *Val, BasicBlock *BB) { | |||
| 674 | ValueLatticeElement Result; // Start Undefined. | |||
| 675 | ||||
| 676 | // If this is the entry block, we must be asking about an argument. The | |||
| 677 | // value is overdefined. | |||
| 678 | if (BB->isEntryBlock()) { | |||
| 679 | assert(isa<Argument>(Val) && "Unknown live-in to the entry block")(static_cast <bool> (isa<Argument>(Val) && "Unknown live-in to the entry block") ? void (0) : __assert_fail ("isa<Argument>(Val) && \"Unknown live-in to the entry block\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 679, __extension__ __PRETTY_FUNCTION__ )); | |||
| 680 | return ValueLatticeElement::getOverdefined(); | |||
| 681 | } | |||
| 682 | ||||
| 683 | // Loop over all of our predecessors, merging what we know from them into | |||
| 684 | // result. If we encounter an unexplored predecessor, we eagerly explore it | |||
| 685 | // in a depth first manner. In practice, this has the effect of discovering | |||
| 686 | // paths we can't analyze eagerly without spending compile times analyzing | |||
| 687 | // other paths. This heuristic benefits from the fact that predecessors are | |||
| 688 | // frequently arranged such that dominating ones come first and we quickly | |||
| 689 | // find a path to function entry. TODO: We should consider explicitly | |||
| 690 | // canonicalizing to make this true rather than relying on this happy | |||
| 691 | // accident. | |||
| 692 | for (BasicBlock *Pred : predecessors(BB)) { | |||
| 693 | Optional<ValueLatticeElement> EdgeResult = getEdgeValue(Val, Pred, BB); | |||
| 694 | if (!EdgeResult) | |||
| 695 | // Explore that input, then return here | |||
| 696 | return None; | |||
| 697 | ||||
| 698 | Result.mergeIn(*EdgeResult); | |||
| 699 | ||||
| 700 | // If we hit overdefined, exit early. The BlockVals entry is already set | |||
| 701 | // to overdefined. | |||
| 702 | if (Result.isOverdefined()) { | |||
| 703 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined because of pred (non local).\n" ; } } while (false) | |||
| 704 | << "' - overdefined because of pred (non local).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined because of pred (non local).\n" ; } } while (false); | |||
| 705 | return Result; | |||
| 706 | } | |||
| 707 | } | |||
| 708 | ||||
| 709 | // Return the merged value, which is more precise than 'overdefined'. | |||
| 710 | assert(!Result.isOverdefined())(static_cast <bool> (!Result.isOverdefined()) ? void (0 ) : __assert_fail ("!Result.isOverdefined()", "llvm/lib/Analysis/LazyValueInfo.cpp" , 710, __extension__ __PRETTY_FUNCTION__)); | |||
| 711 | return Result; | |||
| 712 | } | |||
| 713 | ||||
| 714 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValuePHINode( | |||
| 715 | PHINode *PN, BasicBlock *BB) { | |||
| 716 | ValueLatticeElement Result; // Start Undefined. | |||
| 717 | ||||
| 718 | // Loop over all of our predecessors, merging what we know from them into | |||
| 719 | // result. See the comment about the chosen traversal order in | |||
| 720 | // solveBlockValueNonLocal; the same reasoning applies here. | |||
| 721 | for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { | |||
| 722 | BasicBlock *PhiBB = PN->getIncomingBlock(i); | |||
| 723 | Value *PhiVal = PN->getIncomingValue(i); | |||
| 724 | // Note that we can provide PN as the context value to getEdgeValue, even | |||
| 725 | // though the results will be cached, because PN is the value being used as | |||
| 726 | // the cache key in the caller. | |||
| 727 | Optional<ValueLatticeElement> EdgeResult = | |||
| 728 | getEdgeValue(PhiVal, PhiBB, BB, PN); | |||
| 729 | if (!EdgeResult) | |||
| 730 | // Explore that input, then return here | |||
| 731 | return None; | |||
| 732 | ||||
| 733 | Result.mergeIn(*EdgeResult); | |||
| 734 | ||||
| 735 | // If we hit overdefined, exit early. The BlockVals entry is already set | |||
| 736 | // to overdefined. | |||
| 737 | if (Result.isOverdefined()) { | |||
| 738 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined because of pred (local).\n" ; } } while (false) | |||
| 739 | << "' - overdefined because of pred (local).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined because of pred (local).\n" ; } } while (false); | |||
| 740 | ||||
| 741 | return Result; | |||
| 742 | } | |||
| 743 | } | |||
| 744 | ||||
| 745 | // Return the merged value, which is more precise than 'overdefined'. | |||
| 746 | assert(!Result.isOverdefined() && "Possible PHI in entry block?")(static_cast <bool> (!Result.isOverdefined() && "Possible PHI in entry block?") ? void (0) : __assert_fail ( "!Result.isOverdefined() && \"Possible PHI in entry block?\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 746, __extension__ __PRETTY_FUNCTION__ )); | |||
| 747 | return Result; | |||
| 748 | } | |||
| 749 | ||||
| 750 | static ValueLatticeElement getValueFromCondition(Value *Val, Value *Cond, | |||
| 751 | bool isTrueDest = true); | |||
| 752 | ||||
| 753 | // If we can determine a constraint on the value given conditions assumed by | |||
| 754 | // the program, intersect those constraints with BBLV | |||
| 755 | void LazyValueInfoImpl::intersectAssumeOrGuardBlockValueConstantRange( | |||
| 756 | Value *Val, ValueLatticeElement &BBLV, Instruction *BBI) { | |||
| 757 | BBI = BBI ? BBI : dyn_cast<Instruction>(Val); | |||
| 758 | if (!BBI) | |||
| 759 | return; | |||
| 760 | ||||
| 761 | BasicBlock *BB = BBI->getParent(); | |||
| 762 | for (auto &AssumeVH : AC->assumptionsFor(Val)) { | |||
| 763 | if (!AssumeVH) | |||
| 764 | continue; | |||
| 765 | ||||
| 766 | // Only check assumes in the block of the context instruction. Other | |||
| 767 | // assumes will have already been taken into account when the value was | |||
| 768 | // propagated from predecessor blocks. | |||
| 769 | auto *I = cast<CallInst>(AssumeVH); | |||
| 770 | if (I->getParent() != BB || !isValidAssumeForContext(I, BBI)) | |||
| 771 | continue; | |||
| 772 | ||||
| 773 | BBLV = intersect(BBLV, getValueFromCondition(Val, I->getArgOperand(0))); | |||
| 774 | } | |||
| 775 | ||||
| 776 | // If guards are not used in the module, don't spend time looking for them | |||
| 777 | if (GuardDecl && !GuardDecl->use_empty() && | |||
| 778 | BBI->getIterator() != BB->begin()) { | |||
| 779 | for (Instruction &I : make_range(std::next(BBI->getIterator().getReverse()), | |||
| 780 | BB->rend())) { | |||
| 781 | Value *Cond = nullptr; | |||
| 782 | if (match(&I, m_Intrinsic<Intrinsic::experimental_guard>(m_Value(Cond)))) | |||
| 783 | BBLV = intersect(BBLV, getValueFromCondition(Val, Cond)); | |||
| 784 | } | |||
| 785 | } | |||
| 786 | ||||
| 787 | if (BBLV.isOverdefined()) { | |||
| 788 | // Check whether we're checking at the terminator, and the pointer has | |||
| 789 | // been dereferenced in this block. | |||
| 790 | PointerType *PTy = dyn_cast<PointerType>(Val->getType()); | |||
| 791 | if (PTy && BB->getTerminator() == BBI && | |||
| 792 | isNonNullAtEndOfBlock(Val, BB)) | |||
| 793 | BBLV = ValueLatticeElement::getNot(ConstantPointerNull::get(PTy)); | |||
| 794 | } | |||
| 795 | } | |||
| 796 | ||||
| 797 | static ConstantRange getConstantRangeOrFull(const ValueLatticeElement &Val, | |||
| 798 | Type *Ty, const DataLayout &DL) { | |||
| 799 | if (Val.isConstantRange()) | |||
| 800 | return Val.getConstantRange(); | |||
| 801 | return ConstantRange::getFull(DL.getTypeSizeInBits(Ty)); | |||
| 802 | } | |||
| 803 | ||||
| 804 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueSelect( | |||
| 805 | SelectInst *SI, BasicBlock *BB) { | |||
| 806 | // Recurse on our inputs if needed | |||
| 807 | Optional<ValueLatticeElement> OptTrueVal = | |||
| 808 | getBlockValue(SI->getTrueValue(), BB, SI); | |||
| 809 | if (!OptTrueVal) | |||
| 810 | return None; | |||
| 811 | ValueLatticeElement &TrueVal = *OptTrueVal; | |||
| 812 | ||||
| 813 | Optional<ValueLatticeElement> OptFalseVal = | |||
| 814 | getBlockValue(SI->getFalseValue(), BB, SI); | |||
| 815 | if (!OptFalseVal) | |||
| 816 | return None; | |||
| 817 | ValueLatticeElement &FalseVal = *OptFalseVal; | |||
| 818 | ||||
| 819 | if (TrueVal.isConstantRange() || FalseVal.isConstantRange()) { | |||
| 820 | const ConstantRange &TrueCR = | |||
| 821 | getConstantRangeOrFull(TrueVal, SI->getType(), DL); | |||
| 822 | const ConstantRange &FalseCR = | |||
| 823 | getConstantRangeOrFull(FalseVal, SI->getType(), DL); | |||
| 824 | Value *LHS = nullptr; | |||
| 825 | Value *RHS = nullptr; | |||
| 826 | SelectPatternResult SPR = matchSelectPattern(SI, LHS, RHS); | |||
| 827 | // Is this a min specifically of our two inputs? (Avoid the risk of | |||
| 828 | // ValueTracking getting smarter looking back past our immediate inputs.) | |||
| 829 | if (SelectPatternResult::isMinOrMax(SPR.Flavor) && | |||
| 830 | ((LHS == SI->getTrueValue() && RHS == SI->getFalseValue()) || | |||
| 831 | (RHS == SI->getTrueValue() && LHS == SI->getFalseValue()))) { | |||
| 832 | ConstantRange ResultCR = [&]() { | |||
| 833 | switch (SPR.Flavor) { | |||
| 834 | default: | |||
| 835 | llvm_unreachable("unexpected minmax type!")::llvm::llvm_unreachable_internal("unexpected minmax type!", "llvm/lib/Analysis/LazyValueInfo.cpp" , 835); | |||
| 836 | case SPF_SMIN: /// Signed minimum | |||
| 837 | return TrueCR.smin(FalseCR); | |||
| 838 | case SPF_UMIN: /// Unsigned minimum | |||
| 839 | return TrueCR.umin(FalseCR); | |||
| 840 | case SPF_SMAX: /// Signed maximum | |||
| 841 | return TrueCR.smax(FalseCR); | |||
| 842 | case SPF_UMAX: /// Unsigned maximum | |||
| 843 | return TrueCR.umax(FalseCR); | |||
| 844 | }; | |||
| 845 | }(); | |||
| 846 | return ValueLatticeElement::getRange( | |||
| 847 | ResultCR, TrueVal.isConstantRangeIncludingUndef() || | |||
| 848 | FalseVal.isConstantRangeIncludingUndef()); | |||
| 849 | } | |||
| 850 | ||||
| 851 | if (SPR.Flavor == SPF_ABS) { | |||
| 852 | if (LHS == SI->getTrueValue()) | |||
| 853 | return ValueLatticeElement::getRange( | |||
| 854 | TrueCR.abs(), TrueVal.isConstantRangeIncludingUndef()); | |||
| 855 | if (LHS == SI->getFalseValue()) | |||
| 856 | return ValueLatticeElement::getRange( | |||
| 857 | FalseCR.abs(), FalseVal.isConstantRangeIncludingUndef()); | |||
| 858 | } | |||
| 859 | ||||
| 860 | if (SPR.Flavor == SPF_NABS) { | |||
| 861 | ConstantRange Zero(APInt::getZero(TrueCR.getBitWidth())); | |||
| 862 | if (LHS == SI->getTrueValue()) | |||
| 863 | return ValueLatticeElement::getRange( | |||
| 864 | Zero.sub(TrueCR.abs()), FalseVal.isConstantRangeIncludingUndef()); | |||
| 865 | if (LHS == SI->getFalseValue()) | |||
| 866 | return ValueLatticeElement::getRange( | |||
| 867 | Zero.sub(FalseCR.abs()), FalseVal.isConstantRangeIncludingUndef()); | |||
| 868 | } | |||
| 869 | } | |||
| 870 | ||||
| 871 | // Can we constrain the facts about the true and false values by using the | |||
| 872 | // condition itself? This shows up with idioms like e.g. select(a > 5, a, 5). | |||
| 873 | // TODO: We could potentially refine an overdefined true value above. | |||
| 874 | Value *Cond = SI->getCondition(); | |||
| 875 | TrueVal = intersect(TrueVal, | |||
| 876 | getValueFromCondition(SI->getTrueValue(), Cond, true)); | |||
| 877 | FalseVal = intersect(FalseVal, | |||
| 878 | getValueFromCondition(SI->getFalseValue(), Cond, false)); | |||
| 879 | ||||
| 880 | ValueLatticeElement Result = TrueVal; | |||
| 881 | Result.mergeIn(FalseVal); | |||
| 882 | return Result; | |||
| 883 | } | |||
| 884 | ||||
| 885 | Optional<ConstantRange> LazyValueInfoImpl::getRangeFor(Value *V, | |||
| 886 | Instruction *CxtI, | |||
| 887 | BasicBlock *BB) { | |||
| 888 | Optional<ValueLatticeElement> OptVal = getBlockValue(V, BB, CxtI); | |||
| 889 | if (!OptVal) | |||
| 890 | return None; | |||
| 891 | return getConstantRangeOrFull(*OptVal, V->getType(), DL); | |||
| 892 | } | |||
| 893 | ||||
| 894 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueCast( | |||
| 895 | CastInst *CI, BasicBlock *BB) { | |||
| 896 | // Without knowing how wide the input is, we can't analyze it in any useful | |||
| 897 | // way. | |||
| 898 | if (!CI->getOperand(0)->getType()->isSized()) | |||
| 899 | return ValueLatticeElement::getOverdefined(); | |||
| 900 | ||||
| 901 | // Filter out casts we don't know how to reason about before attempting to | |||
| 902 | // recurse on our operand. This can cut a long search short if we know we're | |||
| 903 | // not going to be able to get any useful information anways. | |||
| 904 | switch (CI->getOpcode()) { | |||
| 905 | case Instruction::Trunc: | |||
| 906 | case Instruction::SExt: | |||
| 907 | case Instruction::ZExt: | |||
| 908 | case Instruction::BitCast: | |||
| 909 | break; | |||
| 910 | default: | |||
| 911 | // Unhandled instructions are overdefined. | |||
| 912 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined (unknown cast).\n" ; } } while (false) | |||
| 913 | << "' - overdefined (unknown cast).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined (unknown cast).\n" ; } } while (false); | |||
| 914 | return ValueLatticeElement::getOverdefined(); | |||
| 915 | } | |||
| 916 | ||||
| 917 | // Figure out the range of the LHS. If that fails, we still apply the | |||
| 918 | // transfer rule on the full set since we may be able to locally infer | |||
| 919 | // interesting facts. | |||
| 920 | Optional<ConstantRange> LHSRes = getRangeFor(CI->getOperand(0), CI, BB); | |||
| 921 | if (!LHSRes.hasValue()) | |||
| 922 | // More work to do before applying this transfer rule. | |||
| 923 | return None; | |||
| 924 | const ConstantRange &LHSRange = LHSRes.getValue(); | |||
| 925 | ||||
| 926 | const unsigned ResultBitWidth = CI->getType()->getIntegerBitWidth(); | |||
| 927 | ||||
| 928 | // NOTE: We're currently limited by the set of operations that ConstantRange | |||
| 929 | // can evaluate symbolically. Enhancing that set will allows us to analyze | |||
| 930 | // more definitions. | |||
| 931 | return ValueLatticeElement::getRange(LHSRange.castOp(CI->getOpcode(), | |||
| 932 | ResultBitWidth)); | |||
| 933 | } | |||
| 934 | ||||
| 935 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueBinaryOpImpl( | |||
| 936 | Instruction *I, BasicBlock *BB, | |||
| 937 | std::function<ConstantRange(const ConstantRange &, | |||
| 938 | const ConstantRange &)> OpFn) { | |||
| 939 | // Figure out the ranges of the operands. If that fails, use a | |||
| 940 | // conservative range, but apply the transfer rule anyways. This | |||
| 941 | // lets us pick up facts from expressions like "and i32 (call i32 | |||
| 942 | // @foo()), 32" | |||
| 943 | Optional<ConstantRange> LHSRes = getRangeFor(I->getOperand(0), I, BB); | |||
| 944 | Optional<ConstantRange> RHSRes = getRangeFor(I->getOperand(1), I, BB); | |||
| 945 | if (!LHSRes.hasValue() || !RHSRes.hasValue()) | |||
| 946 | // More work to do before applying this transfer rule. | |||
| 947 | return None; | |||
| 948 | ||||
| 949 | const ConstantRange &LHSRange = LHSRes.getValue(); | |||
| 950 | const ConstantRange &RHSRange = RHSRes.getValue(); | |||
| 951 | return ValueLatticeElement::getRange(OpFn(LHSRange, RHSRange)); | |||
| 952 | } | |||
| 953 | ||||
| 954 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueBinaryOp( | |||
| 955 | BinaryOperator *BO, BasicBlock *BB) { | |||
| 956 | assert(BO->getOperand(0)->getType()->isSized() &&(static_cast <bool> (BO->getOperand(0)->getType() ->isSized() && "all operands to binary operators are sized" ) ? void (0) : __assert_fail ("BO->getOperand(0)->getType()->isSized() && \"all operands to binary operators are sized\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 957, __extension__ __PRETTY_FUNCTION__ )) | |||
| 957 | "all operands to binary operators are sized")(static_cast <bool> (BO->getOperand(0)->getType() ->isSized() && "all operands to binary operators are sized" ) ? void (0) : __assert_fail ("BO->getOperand(0)->getType()->isSized() && \"all operands to binary operators are sized\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 957, __extension__ __PRETTY_FUNCTION__ )); | |||
| 958 | if (BO->getOpcode() == Instruction::Xor) { | |||
| 959 | // Xor is the only operation not supported by ConstantRange::binaryOp(). | |||
| 960 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined (unknown binary operator).\n" ; } } while (false) | |||
| 961 | << "' - overdefined (unknown binary operator).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined (unknown binary operator).\n" ; } } while (false); | |||
| 962 | return ValueLatticeElement::getOverdefined(); | |||
| 963 | } | |||
| 964 | ||||
| 965 | if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(BO)) { | |||
| 966 | unsigned NoWrapKind = 0; | |||
| 967 | if (OBO->hasNoUnsignedWrap()) | |||
| 968 | NoWrapKind |= OverflowingBinaryOperator::NoUnsignedWrap; | |||
| 969 | if (OBO->hasNoSignedWrap()) | |||
| 970 | NoWrapKind |= OverflowingBinaryOperator::NoSignedWrap; | |||
| 971 | ||||
| 972 | return solveBlockValueBinaryOpImpl( | |||
| 973 | BO, BB, | |||
| 974 | [BO, NoWrapKind](const ConstantRange &CR1, const ConstantRange &CR2) { | |||
| 975 | return CR1.overflowingBinaryOp(BO->getOpcode(), CR2, NoWrapKind); | |||
| 976 | }); | |||
| 977 | } | |||
| 978 | ||||
| 979 | return solveBlockValueBinaryOpImpl( | |||
| 980 | BO, BB, [BO](const ConstantRange &CR1, const ConstantRange &CR2) { | |||
| 981 | return CR1.binaryOp(BO->getOpcode(), CR2); | |||
| 982 | }); | |||
| 983 | } | |||
| 984 | ||||
| 985 | Optional<ValueLatticeElement> | |||
| 986 | LazyValueInfoImpl::solveBlockValueOverflowIntrinsic(WithOverflowInst *WO, | |||
| 987 | BasicBlock *BB) { | |||
| 988 | return solveBlockValueBinaryOpImpl( | |||
| 989 | WO, BB, [WO](const ConstantRange &CR1, const ConstantRange &CR2) { | |||
| 990 | return CR1.binaryOp(WO->getBinaryOp(), CR2); | |||
| 991 | }); | |||
| 992 | } | |||
| 993 | ||||
| 994 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueIntrinsic( | |||
| 995 | IntrinsicInst *II, BasicBlock *BB) { | |||
| 996 | if (!ConstantRange::isIntrinsicSupported(II->getIntrinsicID())) { | |||
| 997 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - unknown intrinsic.\n"; } } while (false) | |||
| 998 | << "' - unknown intrinsic.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - unknown intrinsic.\n"; } } while (false); | |||
| 999 | return getFromRangeMetadata(II); | |||
| 1000 | } | |||
| 1001 | ||||
| 1002 | SmallVector<ConstantRange, 2> OpRanges; | |||
| 1003 | for (Value *Op : II->args()) { | |||
| 1004 | Optional<ConstantRange> Range = getRangeFor(Op, II, BB); | |||
| 1005 | if (!Range) | |||
| 1006 | return None; | |||
| 1007 | OpRanges.push_back(*Range); | |||
| 1008 | } | |||
| 1009 | ||||
| 1010 | return ValueLatticeElement::getRange( | |||
| 1011 | ConstantRange::intrinsic(II->getIntrinsicID(), OpRanges)); | |||
| 1012 | } | |||
| 1013 | ||||
| 1014 | Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueExtractValue( | |||
| 1015 | ExtractValueInst *EVI, BasicBlock *BB) { | |||
| 1016 | if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand())) | |||
| 1017 | if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 0) | |||
| 1018 | return solveBlockValueOverflowIntrinsic(WO, BB); | |||
| 1019 | ||||
| 1020 | // Handle extractvalue of insertvalue to allow further simplification | |||
| 1021 | // based on replaced with.overflow intrinsics. | |||
| 1022 | if (Value *V = SimplifyExtractValueInst( | |||
| 1023 | EVI->getAggregateOperand(), EVI->getIndices(), | |||
| 1024 | EVI->getModule()->getDataLayout())) | |||
| 1025 | return getBlockValue(V, BB, EVI); | |||
| 1026 | ||||
| 1027 | LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined (unknown extractvalue).\n" ; } } while (false) | |||
| 1028 | << "' - overdefined (unknown extractvalue).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " compute BB '" << BB->getName() << "' - overdefined (unknown extractvalue).\n" ; } } while (false); | |||
| 1029 | return ValueLatticeElement::getOverdefined(); | |||
| 1030 | } | |||
| 1031 | ||||
| 1032 | static bool matchICmpOperand(APInt &Offset, Value *LHS, Value *Val, | |||
| 1033 | ICmpInst::Predicate Pred) { | |||
| 1034 | if (LHS == Val) | |||
| 1035 | return true; | |||
| 1036 | ||||
| 1037 | // Handle range checking idiom produced by InstCombine. We will subtract the | |||
| 1038 | // offset from the allowed range for RHS in this case. | |||
| 1039 | const APInt *C; | |||
| 1040 | if (match(LHS, m_Add(m_Specific(Val), m_APInt(C)))) { | |||
| 1041 | Offset = *C; | |||
| 1042 | return true; | |||
| 1043 | } | |||
| 1044 | ||||
| 1045 | // Handle the symmetric case. This appears in saturation patterns like | |||
| 1046 | // (x == 16) ? 16 : (x + 1). | |||
| 1047 | if (match(Val, m_Add(m_Specific(LHS), m_APInt(C)))) { | |||
| 1048 | Offset = -*C; | |||
| 1049 | return true; | |||
| 1050 | } | |||
| 1051 | ||||
| 1052 | // If (x | y) < C, then (x < C) && (y < C). | |||
| 1053 | if (match(LHS, m_c_Or(m_Specific(Val), m_Value())) && | |||
| 1054 | (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE)) | |||
| 1055 | return true; | |||
| 1056 | ||||
| 1057 | // If (x & y) > C, then (x > C) && (y > C). | |||
| 1058 | if (match(LHS, m_c_And(m_Specific(Val), m_Value())) && | |||
| 1059 | (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE)) | |||
| 1060 | return true; | |||
| 1061 | ||||
| 1062 | return false; | |||
| 1063 | } | |||
| 1064 | ||||
| 1065 | /// Get value range for a "(Val + Offset) Pred RHS" condition. | |||
| 1066 | static ValueLatticeElement getValueFromSimpleICmpCondition( | |||
| 1067 | CmpInst::Predicate Pred, Value *RHS, const APInt &Offset) { | |||
| 1068 | ConstantRange RHSRange(RHS->getType()->getIntegerBitWidth(), | |||
| 1069 | /*isFullSet=*/true); | |||
| 1070 | if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) | |||
| 1071 | RHSRange = ConstantRange(CI->getValue()); | |||
| 1072 | else if (Instruction *I = dyn_cast<Instruction>(RHS)) | |||
| 1073 | if (auto *Ranges = I->getMetadata(LLVMContext::MD_range)) | |||
| 1074 | RHSRange = getConstantRangeFromMetadata(*Ranges); | |||
| 1075 | ||||
| 1076 | ConstantRange TrueValues = | |||
| 1077 | ConstantRange::makeAllowedICmpRegion(Pred, RHSRange); | |||
| 1078 | return ValueLatticeElement::getRange(TrueValues.subtract(Offset)); | |||
| 1079 | } | |||
| 1080 | ||||
| 1081 | static ValueLatticeElement getValueFromICmpCondition(Value *Val, ICmpInst *ICI, | |||
| 1082 | bool isTrueDest) { | |||
| 1083 | Value *LHS = ICI->getOperand(0); | |||
| 1084 | Value *RHS = ICI->getOperand(1); | |||
| 1085 | ||||
| 1086 | // Get the predicate that must hold along the considered edge. | |||
| 1087 | CmpInst::Predicate EdgePred = | |||
| 1088 | isTrueDest ? ICI->getPredicate() : ICI->getInversePredicate(); | |||
| 1089 | ||||
| 1090 | if (isa<Constant>(RHS)) { | |||
| 1091 | if (ICI->isEquality() && LHS == Val) { | |||
| 1092 | if (EdgePred == ICmpInst::ICMP_EQ) | |||
| 1093 | return ValueLatticeElement::get(cast<Constant>(RHS)); | |||
| 1094 | else if (!isa<UndefValue>(RHS)) | |||
| 1095 | return ValueLatticeElement::getNot(cast<Constant>(RHS)); | |||
| 1096 | } | |||
| 1097 | } | |||
| 1098 | ||||
| 1099 | Type *Ty = Val->getType(); | |||
| 1100 | if (!Ty->isIntegerTy()) | |||
| 1101 | return ValueLatticeElement::getOverdefined(); | |||
| 1102 | ||||
| 1103 | unsigned BitWidth = Ty->getScalarSizeInBits(); | |||
| 1104 | APInt Offset(BitWidth, 0); | |||
| 1105 | if (matchICmpOperand(Offset, LHS, Val, EdgePred)) | |||
| 1106 | return getValueFromSimpleICmpCondition(EdgePred, RHS, Offset); | |||
| 1107 | ||||
| 1108 | CmpInst::Predicate SwappedPred = CmpInst::getSwappedPredicate(EdgePred); | |||
| 1109 | if (matchICmpOperand(Offset, RHS, Val, SwappedPred)) | |||
| 1110 | return getValueFromSimpleICmpCondition(SwappedPred, LHS, Offset); | |||
| 1111 | ||||
| 1112 | const APInt *Mask, *C; | |||
| 1113 | if (match(LHS, m_And(m_Specific(Val), m_APInt(Mask))) && | |||
| 1114 | match(RHS, m_APInt(C))) { | |||
| 1115 | // If (Val & Mask) == C then all the masked bits are known and we can | |||
| 1116 | // compute a value range based on that. | |||
| 1117 | if (EdgePred == ICmpInst::ICMP_EQ) { | |||
| 1118 | KnownBits Known; | |||
| 1119 | Known.Zero = ~*C & *Mask; | |||
| 1120 | Known.One = *C & *Mask; | |||
| 1121 | return ValueLatticeElement::getRange( | |||
| 1122 | ConstantRange::fromKnownBits(Known, /*IsSigned*/ false)); | |||
| 1123 | } | |||
| 1124 | // If (Val & Mask) != 0 then the value must be larger than the lowest set | |||
| 1125 | // bit of Mask. | |||
| 1126 | if (EdgePred == ICmpInst::ICMP_NE && !Mask->isZero() && C->isZero()) { | |||
| 1127 | return ValueLatticeElement::getRange(ConstantRange::getNonEmpty( | |||
| 1128 | APInt::getOneBitSet(BitWidth, Mask->countTrailingZeros()), | |||
| 1129 | APInt::getZero(BitWidth))); | |||
| 1130 | } | |||
| 1131 | } | |||
| 1132 | ||||
| 1133 | // If (X urem Modulus) >= C, then X >= C. | |||
| 1134 | // If trunc X >= C, then X >= C. | |||
| 1135 | // TODO: An upper bound could be computed as well. | |||
| 1136 | if (match(LHS, m_CombineOr(m_URem(m_Specific(Val), m_Value()), | |||
| 1137 | m_Trunc(m_Specific(Val)))) && | |||
| 1138 | match(RHS, m_APInt(C))) { | |||
| 1139 | // Use the icmp region so we don't have to deal with different predicates. | |||
| 1140 | ConstantRange CR = ConstantRange::makeExactICmpRegion(EdgePred, *C); | |||
| 1141 | if (!CR.isEmptySet()) | |||
| 1142 | return ValueLatticeElement::getRange(ConstantRange::getNonEmpty( | |||
| 1143 | CR.getUnsignedMin().zextOrSelf(BitWidth), APInt(BitWidth, 0))); | |||
| 1144 | } | |||
| 1145 | ||||
| 1146 | return ValueLatticeElement::getOverdefined(); | |||
| 1147 | } | |||
| 1148 | ||||
| 1149 | // Handle conditions of the form | |||
| 1150 | // extractvalue(op.with.overflow(%x, C), 1). | |||
| 1151 | static ValueLatticeElement getValueFromOverflowCondition( | |||
| 1152 | Value *Val, WithOverflowInst *WO, bool IsTrueDest) { | |||
| 1153 | // TODO: This only works with a constant RHS for now. We could also compute | |||
| 1154 | // the range of the RHS, but this doesn't fit into the current structure of | |||
| 1155 | // the edge value calculation. | |||
| 1156 | const APInt *C; | |||
| 1157 | if (WO->getLHS() != Val || !match(WO->getRHS(), m_APInt(C))) | |||
| 1158 | return ValueLatticeElement::getOverdefined(); | |||
| 1159 | ||||
| 1160 | // Calculate the possible values of %x for which no overflow occurs. | |||
| 1161 | ConstantRange NWR = ConstantRange::makeExactNoWrapRegion( | |||
| 1162 | WO->getBinaryOp(), *C, WO->getNoWrapKind()); | |||
| 1163 | ||||
| 1164 | // If overflow is false, %x is constrained to NWR. If overflow is true, %x is | |||
| 1165 | // constrained to it's inverse (all values that might cause overflow). | |||
| 1166 | if (IsTrueDest) | |||
| 1167 | NWR = NWR.inverse(); | |||
| 1168 | return ValueLatticeElement::getRange(NWR); | |||
| 1169 | } | |||
| 1170 | ||||
| 1171 | static Optional<ValueLatticeElement> | |||
| 1172 | getValueFromConditionImpl(Value *Val, Value *Cond, bool isTrueDest, | |||
| 1173 | bool isRevisit, | |||
| 1174 | SmallDenseMap<Value *, ValueLatticeElement> &Visited, | |||
| 1175 | SmallVectorImpl<Value *> &Worklist) { | |||
| 1176 | if (!isRevisit) { | |||
| 1177 | if (ICmpInst *ICI = dyn_cast<ICmpInst>(Cond)) | |||
| 1178 | return getValueFromICmpCondition(Val, ICI, isTrueDest); | |||
| 1179 | ||||
| 1180 | if (auto *EVI = dyn_cast<ExtractValueInst>(Cond)) | |||
| 1181 | if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand())) | |||
| 1182 | if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 1) | |||
| 1183 | return getValueFromOverflowCondition(Val, WO, isTrueDest); | |||
| 1184 | } | |||
| 1185 | ||||
| 1186 | Value *L, *R; | |||
| 1187 | bool IsAnd; | |||
| 1188 | if (match(Cond, m_LogicalAnd(m_Value(L), m_Value(R)))) | |||
| 1189 | IsAnd = true; | |||
| 1190 | else if (match(Cond, m_LogicalOr(m_Value(L), m_Value(R)))) | |||
| 1191 | IsAnd = false; | |||
| 1192 | else | |||
| 1193 | return ValueLatticeElement::getOverdefined(); | |||
| 1194 | ||||
| 1195 | auto LV = Visited.find(L); | |||
| 1196 | auto RV = Visited.find(R); | |||
| 1197 | ||||
| 1198 | // if (L && R) -> intersect L and R | |||
| 1199 | // if (!(L || R)) -> intersect L and R | |||
| 1200 | // if (L || R) -> union L and R | |||
| 1201 | // if (!(L && R)) -> union L and R | |||
| 1202 | if ((isTrueDest ^ IsAnd) && (LV != Visited.end())) { | |||
| 1203 | ValueLatticeElement V = LV->second; | |||
| 1204 | if (V.isOverdefined()) | |||
| 1205 | return V; | |||
| 1206 | if (RV != Visited.end()) { | |||
| 1207 | V.mergeIn(RV->second); | |||
| 1208 | return V; | |||
| 1209 | } | |||
| 1210 | } | |||
| 1211 | ||||
| 1212 | if (LV == Visited.end() || RV == Visited.end()) { | |||
| 1213 | assert(!isRevisit)(static_cast <bool> (!isRevisit) ? void (0) : __assert_fail ("!isRevisit", "llvm/lib/Analysis/LazyValueInfo.cpp", 1213, __extension__ __PRETTY_FUNCTION__)); | |||
| 1214 | if (LV == Visited.end()) | |||
| 1215 | Worklist.push_back(L); | |||
| 1216 | if (RV == Visited.end()) | |||
| 1217 | Worklist.push_back(R); | |||
| 1218 | return None; | |||
| 1219 | } | |||
| 1220 | ||||
| 1221 | return intersect(LV->second, RV->second); | |||
| 1222 | } | |||
| 1223 | ||||
| 1224 | ValueLatticeElement getValueFromCondition(Value *Val, Value *Cond, | |||
| 1225 | bool isTrueDest) { | |||
| 1226 | assert(Cond && "precondition")(static_cast <bool> (Cond && "precondition") ? void (0) : __assert_fail ("Cond && \"precondition\"", "llvm/lib/Analysis/LazyValueInfo.cpp" , 1226, __extension__ __PRETTY_FUNCTION__)); | |||
| 1227 | SmallDenseMap<Value*, ValueLatticeElement> Visited; | |||
| 1228 | SmallVector<Value *> Worklist; | |||
| 1229 | ||||
| 1230 | Worklist.push_back(Cond); | |||
| 1231 | do { | |||
| 1232 | Value *CurrentCond = Worklist.back(); | |||
| 1233 | // Insert an Overdefined placeholder into the set to prevent | |||
| 1234 | // infinite recursion if there exists IRs that use not | |||
| 1235 | // dominated by its def as in this example: | |||
| 1236 | // "%tmp3 = or i1 undef, %tmp4" | |||
| 1237 | // "%tmp4 = or i1 undef, %tmp3" | |||
| 1238 | auto Iter = | |||
| 1239 | Visited.try_emplace(CurrentCond, ValueLatticeElement::getOverdefined()); | |||
| 1240 | bool isRevisit = !Iter.second; | |||
| 1241 | Optional<ValueLatticeElement> Result = getValueFromConditionImpl( | |||
| 1242 | Val, CurrentCond, isTrueDest, isRevisit, Visited, Worklist); | |||
| 1243 | if (Result) { | |||
| 1244 | Visited[CurrentCond] = *Result; | |||
| 1245 | Worklist.pop_back(); | |||
| 1246 | } | |||
| 1247 | } while (!Worklist.empty()); | |||
| 1248 | ||||
| 1249 | auto Result = Visited.find(Cond); | |||
| 1250 | assert(Result != Visited.end())(static_cast <bool> (Result != Visited.end()) ? void (0 ) : __assert_fail ("Result != Visited.end()", "llvm/lib/Analysis/LazyValueInfo.cpp" , 1250, __extension__ __PRETTY_FUNCTION__)); | |||
| 1251 | return Result->second; | |||
| 1252 | } | |||
| 1253 | ||||
| 1254 | // Return true if Usr has Op as an operand, otherwise false. | |||
| 1255 | static bool usesOperand(User *Usr, Value *Op) { | |||
| 1256 | return is_contained(Usr->operands(), Op); | |||
| 1257 | } | |||
| 1258 | ||||
| 1259 | // Return true if the instruction type of Val is supported by | |||
| 1260 | // constantFoldUser(). Currently CastInst, BinaryOperator and FreezeInst only. | |||
| 1261 | // Call this before calling constantFoldUser() to find out if it's even worth | |||
| 1262 | // attempting to call it. | |||
| 1263 | static bool isOperationFoldable(User *Usr) { | |||
| 1264 | return isa<CastInst>(Usr) || isa<BinaryOperator>(Usr) || isa<FreezeInst>(Usr); | |||
| 1265 | } | |||
| 1266 | ||||
| 1267 | // Check if Usr can be simplified to an integer constant when the value of one | |||
| 1268 | // of its operands Op is an integer constant OpConstVal. If so, return it as an | |||
| 1269 | // lattice value range with a single element or otherwise return an overdefined | |||
| 1270 | // lattice value. | |||
| 1271 | static ValueLatticeElement constantFoldUser(User *Usr, Value *Op, | |||
| 1272 | const APInt &OpConstVal, | |||
| 1273 | const DataLayout &DL) { | |||
| 1274 | assert(isOperationFoldable(Usr) && "Precondition")(static_cast <bool> (isOperationFoldable(Usr) && "Precondition") ? void (0) : __assert_fail ("isOperationFoldable(Usr) && \"Precondition\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1274, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1275 | Constant* OpConst = Constant::getIntegerValue(Op->getType(), OpConstVal); | |||
| 1276 | // Check if Usr can be simplified to a constant. | |||
| 1277 | if (auto *CI = dyn_cast<CastInst>(Usr)) { | |||
| 1278 | assert(CI->getOperand(0) == Op && "Operand 0 isn't Op")(static_cast <bool> (CI->getOperand(0) == Op && "Operand 0 isn't Op") ? void (0) : __assert_fail ("CI->getOperand(0) == Op && \"Operand 0 isn't Op\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1278, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1279 | if (auto *C = dyn_cast_or_null<ConstantInt>( | |||
| 1280 | SimplifyCastInst(CI->getOpcode(), OpConst, | |||
| 1281 | CI->getDestTy(), DL))) { | |||
| 1282 | return ValueLatticeElement::getRange(ConstantRange(C->getValue())); | |||
| 1283 | } | |||
| 1284 | } else if (auto *BO = dyn_cast<BinaryOperator>(Usr)) { | |||
| 1285 | bool Op0Match = BO->getOperand(0) == Op; | |||
| 1286 | bool Op1Match = BO->getOperand(1) == Op; | |||
| 1287 | assert((Op0Match || Op1Match) &&(static_cast <bool> ((Op0Match || Op1Match) && "Operand 0 nor Operand 1 isn't a match" ) ? void (0) : __assert_fail ("(Op0Match || Op1Match) && \"Operand 0 nor Operand 1 isn't a match\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1288, __extension__ __PRETTY_FUNCTION__ )) | |||
| 1288 | "Operand 0 nor Operand 1 isn't a match")(static_cast <bool> ((Op0Match || Op1Match) && "Operand 0 nor Operand 1 isn't a match" ) ? void (0) : __assert_fail ("(Op0Match || Op1Match) && \"Operand 0 nor Operand 1 isn't a match\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1288, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1289 | Value *LHS = Op0Match ? OpConst : BO->getOperand(0); | |||
| 1290 | Value *RHS = Op1Match ? OpConst : BO->getOperand(1); | |||
| 1291 | if (auto *C = dyn_cast_or_null<ConstantInt>( | |||
| 1292 | SimplifyBinOp(BO->getOpcode(), LHS, RHS, DL))) { | |||
| 1293 | return ValueLatticeElement::getRange(ConstantRange(C->getValue())); | |||
| 1294 | } | |||
| 1295 | } else if (isa<FreezeInst>(Usr)) { | |||
| 1296 | assert(cast<FreezeInst>(Usr)->getOperand(0) == Op && "Operand 0 isn't Op")(static_cast <bool> (cast<FreezeInst>(Usr)->getOperand (0) == Op && "Operand 0 isn't Op") ? void (0) : __assert_fail ("cast<FreezeInst>(Usr)->getOperand(0) == Op && \"Operand 0 isn't Op\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1296, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1297 | return ValueLatticeElement::getRange(ConstantRange(OpConstVal)); | |||
| 1298 | } | |||
| 1299 | return ValueLatticeElement::getOverdefined(); | |||
| 1300 | } | |||
| 1301 | ||||
| 1302 | /// Compute the value of Val on the edge BBFrom -> BBTo. Returns false if | |||
| 1303 | /// Val is not constrained on the edge. Result is unspecified if return value | |||
| 1304 | /// is false. | |||
| 1305 | static Optional<ValueLatticeElement> getEdgeValueLocal(Value *Val, | |||
| 1306 | BasicBlock *BBFrom, | |||
| 1307 | BasicBlock *BBTo) { | |||
| 1308 | // TODO: Handle more complex conditionals. If (v == 0 || v2 < 1) is false, we | |||
| 1309 | // know that v != 0. | |||
| 1310 | if (BranchInst *BI = dyn_cast<BranchInst>(BBFrom->getTerminator())) { | |||
| 1311 | // If this is a conditional branch and only one successor goes to BBTo, then | |||
| 1312 | // we may be able to infer something from the condition. | |||
| 1313 | if (BI->isConditional() && | |||
| 1314 | BI->getSuccessor(0) != BI->getSuccessor(1)) { | |||
| 1315 | bool isTrueDest = BI->getSuccessor(0) == BBTo; | |||
| 1316 | assert(BI->getSuccessor(!isTrueDest) == BBTo &&(static_cast <bool> (BI->getSuccessor(!isTrueDest) == BBTo && "BBTo isn't a successor of BBFrom") ? void ( 0) : __assert_fail ("BI->getSuccessor(!isTrueDest) == BBTo && \"BBTo isn't a successor of BBFrom\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1317, __extension__ __PRETTY_FUNCTION__ )) | |||
| 1317 | "BBTo isn't a successor of BBFrom")(static_cast <bool> (BI->getSuccessor(!isTrueDest) == BBTo && "BBTo isn't a successor of BBFrom") ? void ( 0) : __assert_fail ("BI->getSuccessor(!isTrueDest) == BBTo && \"BBTo isn't a successor of BBFrom\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1317, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1318 | Value *Condition = BI->getCondition(); | |||
| 1319 | ||||
| 1320 | // If V is the condition of the branch itself, then we know exactly what | |||
| 1321 | // it is. | |||
| 1322 | if (Condition == Val) | |||
| 1323 | return ValueLatticeElement::get(ConstantInt::get( | |||
| 1324 | Type::getInt1Ty(Val->getContext()), isTrueDest)); | |||
| 1325 | ||||
| 1326 | // If the condition of the branch is an equality comparison, we may be | |||
| 1327 | // able to infer the value. | |||
| 1328 | ValueLatticeElement Result = getValueFromCondition(Val, Condition, | |||
| 1329 | isTrueDest); | |||
| 1330 | if (!Result.isOverdefined()) | |||
| 1331 | return Result; | |||
| 1332 | ||||
| 1333 | if (User *Usr = dyn_cast<User>(Val)) { | |||
| 1334 | assert(Result.isOverdefined() && "Result isn't overdefined")(static_cast <bool> (Result.isOverdefined() && "Result isn't overdefined" ) ? void (0) : __assert_fail ("Result.isOverdefined() && \"Result isn't overdefined\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1334, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1335 | // Check with isOperationFoldable() first to avoid linearly iterating | |||
| 1336 | // over the operands unnecessarily which can be expensive for | |||
| 1337 | // instructions with many operands. | |||
| 1338 | if (isa<IntegerType>(Usr->getType()) && isOperationFoldable(Usr)) { | |||
| 1339 | const DataLayout &DL = BBTo->getModule()->getDataLayout(); | |||
| 1340 | if (usesOperand(Usr, Condition)) { | |||
| 1341 | // If Val has Condition as an operand and Val can be folded into a | |||
| 1342 | // constant with either Condition == true or Condition == false, | |||
| 1343 | // propagate the constant. | |||
| 1344 | // eg. | |||
| 1345 | // ; %Val is true on the edge to %then. | |||
| 1346 | // %Val = and i1 %Condition, true. | |||
| 1347 | // br %Condition, label %then, label %else | |||
| 1348 | APInt ConditionVal(1, isTrueDest ? 1 : 0); | |||
| 1349 | Result = constantFoldUser(Usr, Condition, ConditionVal, DL); | |||
| 1350 | } else { | |||
| 1351 | // If one of Val's operand has an inferred value, we may be able to | |||
| 1352 | // infer the value of Val. | |||
| 1353 | // eg. | |||
| 1354 | // ; %Val is 94 on the edge to %then. | |||
| 1355 | // %Val = add i8 %Op, 1 | |||
| 1356 | // %Condition = icmp eq i8 %Op, 93 | |||
| 1357 | // br i1 %Condition, label %then, label %else | |||
| 1358 | for (unsigned i = 0; i < Usr->getNumOperands(); ++i) { | |||
| 1359 | Value *Op = Usr->getOperand(i); | |||
| 1360 | ValueLatticeElement OpLatticeVal = | |||
| 1361 | getValueFromCondition(Op, Condition, isTrueDest); | |||
| 1362 | if (Optional<APInt> OpConst = OpLatticeVal.asConstantInteger()) { | |||
| 1363 | Result = constantFoldUser(Usr, Op, OpConst.getValue(), DL); | |||
| 1364 | break; | |||
| 1365 | } | |||
| 1366 | } | |||
| 1367 | } | |||
| 1368 | } | |||
| 1369 | } | |||
| 1370 | if (!Result.isOverdefined()) | |||
| 1371 | return Result; | |||
| 1372 | } | |||
| 1373 | } | |||
| 1374 | ||||
| 1375 | // If the edge was formed by a switch on the value, then we may know exactly | |||
| 1376 | // what it is. | |||
| 1377 | if (SwitchInst *SI = dyn_cast<SwitchInst>(BBFrom->getTerminator())) { | |||
| 1378 | Value *Condition = SI->getCondition(); | |||
| 1379 | if (!isa<IntegerType>(Val->getType())) | |||
| 1380 | return None; | |||
| 1381 | bool ValUsesConditionAndMayBeFoldable = false; | |||
| 1382 | if (Condition != Val) { | |||
| 1383 | // Check if Val has Condition as an operand. | |||
| 1384 | if (User *Usr = dyn_cast<User>(Val)) | |||
| 1385 | ValUsesConditionAndMayBeFoldable = isOperationFoldable(Usr) && | |||
| 1386 | usesOperand(Usr, Condition); | |||
| 1387 | if (!ValUsesConditionAndMayBeFoldable) | |||
| 1388 | return None; | |||
| 1389 | } | |||
| 1390 | assert((Condition == Val || ValUsesConditionAndMayBeFoldable) &&(static_cast <bool> ((Condition == Val || ValUsesConditionAndMayBeFoldable ) && "Condition != Val nor Val doesn't use Condition" ) ? void (0) : __assert_fail ("(Condition == Val || ValUsesConditionAndMayBeFoldable) && \"Condition != Val nor Val doesn't use Condition\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1391, __extension__ __PRETTY_FUNCTION__ )) | |||
| 1391 | "Condition != Val nor Val doesn't use Condition")(static_cast <bool> ((Condition == Val || ValUsesConditionAndMayBeFoldable ) && "Condition != Val nor Val doesn't use Condition" ) ? void (0) : __assert_fail ("(Condition == Val || ValUsesConditionAndMayBeFoldable) && \"Condition != Val nor Val doesn't use Condition\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1391, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1392 | ||||
| 1393 | bool DefaultCase = SI->getDefaultDest() == BBTo; | |||
| 1394 | unsigned BitWidth = Val->getType()->getIntegerBitWidth(); | |||
| 1395 | ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/); | |||
| 1396 | ||||
| 1397 | for (auto Case : SI->cases()) { | |||
| 1398 | APInt CaseValue = Case.getCaseValue()->getValue(); | |||
| 1399 | ConstantRange EdgeVal(CaseValue); | |||
| 1400 | if (ValUsesConditionAndMayBeFoldable) { | |||
| 1401 | User *Usr = cast<User>(Val); | |||
| 1402 | const DataLayout &DL = BBTo->getModule()->getDataLayout(); | |||
| 1403 | ValueLatticeElement EdgeLatticeVal = | |||
| 1404 | constantFoldUser(Usr, Condition, CaseValue, DL); | |||
| 1405 | if (EdgeLatticeVal.isOverdefined()) | |||
| 1406 | return None; | |||
| 1407 | EdgeVal = EdgeLatticeVal.getConstantRange(); | |||
| 1408 | } | |||
| 1409 | if (DefaultCase) { | |||
| 1410 | // It is possible that the default destination is the destination of | |||
| 1411 | // some cases. We cannot perform difference for those cases. | |||
| 1412 | // We know Condition != CaseValue in BBTo. In some cases we can use | |||
| 1413 | // this to infer Val == f(Condition) is != f(CaseValue). For now, we | |||
| 1414 | // only do this when f is identity (i.e. Val == Condition), but we | |||
| 1415 | // should be able to do this for any injective f. | |||
| 1416 | if (Case.getCaseSuccessor() != BBTo && Condition == Val) | |||
| 1417 | EdgesVals = EdgesVals.difference(EdgeVal); | |||
| 1418 | } else if (Case.getCaseSuccessor() == BBTo) | |||
| 1419 | EdgesVals = EdgesVals.unionWith(EdgeVal); | |||
| 1420 | } | |||
| 1421 | return ValueLatticeElement::getRange(std::move(EdgesVals)); | |||
| 1422 | } | |||
| 1423 | return None; | |||
| 1424 | } | |||
| 1425 | ||||
| 1426 | /// Compute the value of Val on the edge BBFrom -> BBTo or the value at | |||
| 1427 | /// the basic block if the edge does not constrain Val. | |||
| 1428 | Optional<ValueLatticeElement> LazyValueInfoImpl::getEdgeValue( | |||
| 1429 | Value *Val, BasicBlock *BBFrom, BasicBlock *BBTo, Instruction *CxtI) { | |||
| 1430 | // If already a constant, there is nothing to compute. | |||
| 1431 | if (Constant *VC = dyn_cast<Constant>(Val)) | |||
| 1432 | return ValueLatticeElement::get(VC); | |||
| 1433 | ||||
| 1434 | ValueLatticeElement LocalResult = getEdgeValueLocal(Val, BBFrom, BBTo) | |||
| 1435 | .getValueOr(ValueLatticeElement::getOverdefined()); | |||
| 1436 | if (hasSingleValue(LocalResult)) | |||
| 1437 | // Can't get any more precise here | |||
| 1438 | return LocalResult; | |||
| 1439 | ||||
| 1440 | Optional<ValueLatticeElement> OptInBlock = | |||
| 1441 | getBlockValue(Val, BBFrom, BBFrom->getTerminator()); | |||
| 1442 | if (!OptInBlock) | |||
| 1443 | return None; | |||
| 1444 | ValueLatticeElement &InBlock = *OptInBlock; | |||
| 1445 | ||||
| 1446 | // We can use the context instruction (generically the ultimate instruction | |||
| 1447 | // the calling pass is trying to simplify) here, even though the result of | |||
| 1448 | // this function is generally cached when called from the solve* functions | |||
| 1449 | // (and that cached result might be used with queries using a different | |||
| 1450 | // context instruction), because when this function is called from the solve* | |||
| 1451 | // functions, the context instruction is not provided. When called from | |||
| 1452 | // LazyValueInfoImpl::getValueOnEdge, the context instruction is provided, | |||
| 1453 | // but then the result is not cached. | |||
| 1454 | intersectAssumeOrGuardBlockValueConstantRange(Val, InBlock, CxtI); | |||
| 1455 | ||||
| 1456 | return intersect(LocalResult, InBlock); | |||
| 1457 | } | |||
| 1458 | ||||
| 1459 | ValueLatticeElement LazyValueInfoImpl::getValueInBlock(Value *V, BasicBlock *BB, | |||
| 1460 | Instruction *CxtI) { | |||
| 1461 | LLVM_DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting block end value " << *V << " at '" << BB->getName() << "'\n"; } } while (false) | |||
| 1462 | << BB->getName() << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting block end value " << *V << " at '" << BB->getName() << "'\n"; } } while (false); | |||
| 1463 | ||||
| 1464 | assert(BlockValueStack.empty() && BlockValueSet.empty())(static_cast <bool> (BlockValueStack.empty() && BlockValueSet.empty()) ? void (0) : __assert_fail ("BlockValueStack.empty() && BlockValueSet.empty()" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1464, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1465 | Optional<ValueLatticeElement> OptResult = getBlockValue(V, BB, CxtI); | |||
| 1466 | if (!OptResult) { | |||
| 1467 | solve(); | |||
| 1468 | OptResult = getBlockValue(V, BB, CxtI); | |||
| 1469 | assert(OptResult && "Value not available after solving")(static_cast <bool> (OptResult && "Value not available after solving" ) ? void (0) : __assert_fail ("OptResult && \"Value not available after solving\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1469, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1470 | } | |||
| 1471 | ||||
| 1472 | ValueLatticeElement Result = *OptResult; | |||
| 1473 | LLVM_DEBUG(dbgs() << " Result = " << Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " Result = " << Result << "\n"; } } while (false); | |||
| 1474 | return Result; | |||
| 1475 | } | |||
| 1476 | ||||
| 1477 | ValueLatticeElement LazyValueInfoImpl::getValueAt(Value *V, Instruction *CxtI) { | |||
| 1478 | LLVM_DEBUG(dbgs() << "LVI Getting value " << *V << " at '" << CxtI->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting value " << *V << " at '" << CxtI->getName() << "'\n" ; } } while (false) | |||
| 1479 | << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting value " << *V << " at '" << CxtI->getName() << "'\n" ; } } while (false); | |||
| 1480 | ||||
| 1481 | if (auto *C = dyn_cast<Constant>(V)) | |||
| 1482 | return ValueLatticeElement::get(C); | |||
| 1483 | ||||
| 1484 | ValueLatticeElement Result = ValueLatticeElement::getOverdefined(); | |||
| 1485 | if (auto *I = dyn_cast<Instruction>(V)) | |||
| 1486 | Result = getFromRangeMetadata(I); | |||
| 1487 | intersectAssumeOrGuardBlockValueConstantRange(V, Result, CxtI); | |||
| 1488 | ||||
| 1489 | LLVM_DEBUG(dbgs() << " Result = " << Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " Result = " << Result << "\n"; } } while (false); | |||
| 1490 | return Result; | |||
| 1491 | } | |||
| 1492 | ||||
| 1493 | ValueLatticeElement LazyValueInfoImpl:: | |||
| 1494 | getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB, | |||
| 1495 | Instruction *CxtI) { | |||
| 1496 | LLVM_DEBUG(dbgs() << "LVI Getting edge value " << *V << " from '"do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting edge value " << *V << " from '" << FromBB->getName() << "' to '" << ToBB->getName() << "'\n" ; } } while (false) | |||
| 1497 | << FromBB->getName() << "' to '" << ToBB->getName()do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting edge value " << *V << " from '" << FromBB->getName() << "' to '" << ToBB->getName() << "'\n" ; } } while (false) | |||
| 1498 | << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << "LVI Getting edge value " << *V << " from '" << FromBB->getName() << "' to '" << ToBB->getName() << "'\n" ; } } while (false); | |||
| 1499 | ||||
| 1500 | Optional<ValueLatticeElement> Result = getEdgeValue(V, FromBB, ToBB, CxtI); | |||
| 1501 | if (!Result) { | |||
| 1502 | solve(); | |||
| 1503 | Result = getEdgeValue(V, FromBB, ToBB, CxtI); | |||
| 1504 | assert(Result && "More work to do after problem solved?")(static_cast <bool> (Result && "More work to do after problem solved?" ) ? void (0) : __assert_fail ("Result && \"More work to do after problem solved?\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1504, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1505 | } | |||
| 1506 | ||||
| 1507 | LLVM_DEBUG(dbgs() << " Result = " << *Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType ("lazy-value-info")) { dbgs() << " Result = " << *Result << "\n"; } } while (false); | |||
| 1508 | return *Result; | |||
| 1509 | } | |||
| 1510 | ||||
| 1511 | void LazyValueInfoImpl::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, | |||
| 1512 | BasicBlock *NewSucc) { | |||
| 1513 | TheCache.threadEdgeImpl(OldSucc, NewSucc); | |||
| 1514 | } | |||
| 1515 | ||||
| 1516 | //===----------------------------------------------------------------------===// | |||
| 1517 | // LazyValueInfo Impl | |||
| 1518 | //===----------------------------------------------------------------------===// | |||
| 1519 | ||||
| 1520 | /// This lazily constructs the LazyValueInfoImpl. | |||
| 1521 | static LazyValueInfoImpl &getImpl(void *&PImpl, AssumptionCache *AC, | |||
| 1522 | const Module *M) { | |||
| 1523 | if (!PImpl) { | |||
| 1524 | assert(M && "getCache() called with a null Module")(static_cast <bool> (M && "getCache() called with a null Module" ) ? void (0) : __assert_fail ("M && \"getCache() called with a null Module\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1524, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1525 | const DataLayout &DL = M->getDataLayout(); | |||
| 1526 | Function *GuardDecl = M->getFunction( | |||
| 1527 | Intrinsic::getName(Intrinsic::experimental_guard)); | |||
| 1528 | PImpl = new LazyValueInfoImpl(AC, DL, GuardDecl); | |||
| 1529 | } | |||
| 1530 | return *static_cast<LazyValueInfoImpl*>(PImpl); | |||
| 1531 | } | |||
| 1532 | ||||
| 1533 | bool LazyValueInfoWrapperPass::runOnFunction(Function &F) { | |||
| 1534 | Info.AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F); | |||
| 1535 | Info.TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F); | |||
| 1536 | ||||
| 1537 | if (Info.PImpl) | |||
| 1538 | getImpl(Info.PImpl, Info.AC, F.getParent()).clear(); | |||
| 1539 | ||||
| 1540 | // Fully lazy. | |||
| 1541 | return false; | |||
| 1542 | } | |||
| 1543 | ||||
| 1544 | void LazyValueInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { | |||
| 1545 | AU.setPreservesAll(); | |||
| 1546 | AU.addRequired<AssumptionCacheTracker>(); | |||
| 1547 | AU.addRequired<TargetLibraryInfoWrapperPass>(); | |||
| 1548 | } | |||
| 1549 | ||||
| 1550 | LazyValueInfo &LazyValueInfoWrapperPass::getLVI() { return Info; } | |||
| 1551 | ||||
| 1552 | LazyValueInfo::~LazyValueInfo() { releaseMemory(); } | |||
| 1553 | ||||
| 1554 | void LazyValueInfo::releaseMemory() { | |||
| 1555 | // If the cache was allocated, free it. | |||
| 1556 | if (PImpl) { | |||
| 1557 | delete &getImpl(PImpl, AC, nullptr); | |||
| 1558 | PImpl = nullptr; | |||
| 1559 | } | |||
| 1560 | } | |||
| 1561 | ||||
| 1562 | bool LazyValueInfo::invalidate(Function &F, const PreservedAnalyses &PA, | |||
| 1563 | FunctionAnalysisManager::Invalidator &Inv) { | |||
| 1564 | // We need to invalidate if we have either failed to preserve this analyses | |||
| 1565 | // result directly or if any of its dependencies have been invalidated. | |||
| 1566 | auto PAC = PA.getChecker<LazyValueAnalysis>(); | |||
| 1567 | if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>())) | |||
| 1568 | return true; | |||
| 1569 | ||||
| 1570 | return false; | |||
| 1571 | } | |||
| 1572 | ||||
| 1573 | void LazyValueInfoWrapperPass::releaseMemory() { Info.releaseMemory(); } | |||
| 1574 | ||||
| 1575 | LazyValueInfo LazyValueAnalysis::run(Function &F, | |||
| 1576 | FunctionAnalysisManager &FAM) { | |||
| 1577 | auto &AC = FAM.getResult<AssumptionAnalysis>(F); | |||
| 1578 | auto &TLI = FAM.getResult<TargetLibraryAnalysis>(F); | |||
| 1579 | ||||
| 1580 | return LazyValueInfo(&AC, &F.getParent()->getDataLayout(), &TLI); | |||
| 1581 | } | |||
| 1582 | ||||
| 1583 | /// Returns true if we can statically tell that this value will never be a | |||
| 1584 | /// "useful" constant. In practice, this means we've got something like an | |||
| 1585 | /// alloca or a malloc call for which a comparison against a constant can | |||
| 1586 | /// only be guarding dead code. Note that we are potentially giving up some | |||
| 1587 | /// precision in dead code (a constant result) in favour of avoiding a | |||
| 1588 | /// expensive search for a easily answered common query. | |||
| 1589 | static bool isKnownNonConstant(Value *V) { | |||
| 1590 | V = V->stripPointerCasts(); | |||
| 1591 | // The return val of alloc cannot be a Constant. | |||
| 1592 | if (isa<AllocaInst>(V)) | |||
| 1593 | return true; | |||
| 1594 | return false; | |||
| 1595 | } | |||
| 1596 | ||||
| 1597 | Constant *LazyValueInfo::getConstant(Value *V, Instruction *CxtI) { | |||
| 1598 | // Bail out early if V is known not to be a Constant. | |||
| 1599 | if (isKnownNonConstant(V)) | |||
| 1600 | return nullptr; | |||
| 1601 | ||||
| 1602 | BasicBlock *BB = CxtI->getParent(); | |||
| 1603 | ValueLatticeElement Result = | |||
| 1604 | getImpl(PImpl, AC, BB->getModule()).getValueInBlock(V, BB, CxtI); | |||
| 1605 | ||||
| 1606 | if (Result.isConstant()) | |||
| 1607 | return Result.getConstant(); | |||
| 1608 | if (Result.isConstantRange()) { | |||
| 1609 | const ConstantRange &CR = Result.getConstantRange(); | |||
| 1610 | if (const APInt *SingleVal = CR.getSingleElement()) | |||
| 1611 | return ConstantInt::get(V->getContext(), *SingleVal); | |||
| 1612 | } | |||
| 1613 | return nullptr; | |||
| 1614 | } | |||
| 1615 | ||||
| 1616 | ConstantRange LazyValueInfo::getConstantRange(Value *V, Instruction *CxtI, | |||
| 1617 | bool UndefAllowed) { | |||
| 1618 | assert(V->getType()->isIntegerTy())(static_cast <bool> (V->getType()->isIntegerTy()) ? void (0) : __assert_fail ("V->getType()->isIntegerTy()" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1618, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1619 | unsigned Width = V->getType()->getIntegerBitWidth(); | |||
| 1620 | BasicBlock *BB = CxtI->getParent(); | |||
| 1621 | ValueLatticeElement Result = | |||
| 1622 | getImpl(PImpl, AC, BB->getModule()).getValueInBlock(V, BB, CxtI); | |||
| 1623 | if (Result.isUnknown()) | |||
| 1624 | return ConstantRange::getEmpty(Width); | |||
| 1625 | if (Result.isConstantRange(UndefAllowed)) | |||
| 1626 | return Result.getConstantRange(UndefAllowed); | |||
| 1627 | // We represent ConstantInt constants as constant ranges but other kinds | |||
| 1628 | // of integer constants, i.e. ConstantExpr will be tagged as constants | |||
| 1629 | assert(!(Result.isConstant() && isa<ConstantInt>(Result.getConstant())) &&(static_cast <bool> (!(Result.isConstant() && isa <ConstantInt>(Result.getConstant())) && "ConstantInt value must be represented as constantrange" ) ? void (0) : __assert_fail ("!(Result.isConstant() && isa<ConstantInt>(Result.getConstant())) && \"ConstantInt value must be represented as constantrange\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1630, __extension__ __PRETTY_FUNCTION__ )) | |||
| 1630 | "ConstantInt value must be represented as constantrange")(static_cast <bool> (!(Result.isConstant() && isa <ConstantInt>(Result.getConstant())) && "ConstantInt value must be represented as constantrange" ) ? void (0) : __assert_fail ("!(Result.isConstant() && isa<ConstantInt>(Result.getConstant())) && \"ConstantInt value must be represented as constantrange\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1630, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1631 | return ConstantRange::getFull(Width); | |||
| 1632 | } | |||
| 1633 | ||||
| 1634 | /// Determine whether the specified value is known to be a | |||
| 1635 | /// constant on the specified edge. Return null if not. | |||
| 1636 | Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB, | |||
| 1637 | BasicBlock *ToBB, | |||
| 1638 | Instruction *CxtI) { | |||
| 1639 | Module *M = FromBB->getModule(); | |||
| 1640 | ValueLatticeElement Result = | |||
| 1641 | getImpl(PImpl, AC, M).getValueOnEdge(V, FromBB, ToBB, CxtI); | |||
| ||||
| 1642 | ||||
| 1643 | if (Result.isConstant()) | |||
| 1644 | return Result.getConstant(); | |||
| 1645 | if (Result.isConstantRange()) { | |||
| 1646 | const ConstantRange &CR = Result.getConstantRange(); | |||
| 1647 | if (const APInt *SingleVal = CR.getSingleElement()) | |||
| 1648 | return ConstantInt::get(V->getContext(), *SingleVal); | |||
| 1649 | } | |||
| 1650 | return nullptr; | |||
| 1651 | } | |||
| 1652 | ||||
| 1653 | ConstantRange LazyValueInfo::getConstantRangeOnEdge(Value *V, | |||
| 1654 | BasicBlock *FromBB, | |||
| 1655 | BasicBlock *ToBB, | |||
| 1656 | Instruction *CxtI) { | |||
| 1657 | unsigned Width = V->getType()->getIntegerBitWidth(); | |||
| 1658 | Module *M = FromBB->getModule(); | |||
| 1659 | ValueLatticeElement Result = | |||
| 1660 | getImpl(PImpl, AC, M).getValueOnEdge(V, FromBB, ToBB, CxtI); | |||
| 1661 | ||||
| 1662 | if (Result.isUnknown()) | |||
| 1663 | return ConstantRange::getEmpty(Width); | |||
| 1664 | if (Result.isConstantRange()) | |||
| 1665 | return Result.getConstantRange(); | |||
| 1666 | // We represent ConstantInt constants as constant ranges but other kinds | |||
| 1667 | // of integer constants, i.e. ConstantExpr will be tagged as constants | |||
| 1668 | assert(!(Result.isConstant() && isa<ConstantInt>(Result.getConstant())) &&(static_cast <bool> (!(Result.isConstant() && isa <ConstantInt>(Result.getConstant())) && "ConstantInt value must be represented as constantrange" ) ? void (0) : __assert_fail ("!(Result.isConstant() && isa<ConstantInt>(Result.getConstant())) && \"ConstantInt value must be represented as constantrange\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1669, __extension__ __PRETTY_FUNCTION__ )) | |||
| 1669 | "ConstantInt value must be represented as constantrange")(static_cast <bool> (!(Result.isConstant() && isa <ConstantInt>(Result.getConstant())) && "ConstantInt value must be represented as constantrange" ) ? void (0) : __assert_fail ("!(Result.isConstant() && isa<ConstantInt>(Result.getConstant())) && \"ConstantInt value must be represented as constantrange\"" , "llvm/lib/Analysis/LazyValueInfo.cpp", 1669, __extension__ __PRETTY_FUNCTION__ )); | |||
| 1670 | return ConstantRange::getFull(Width); | |||
| 1671 | } | |||
| 1672 | ||||
| 1673 | static LazyValueInfo::Tristate | |||
| 1674 | getPredicateResult(unsigned Pred, Constant *C, const ValueLatticeElement &Val, | |||
| 1675 | const DataLayout &DL, TargetLibraryInfo *TLI) { | |||
| 1676 | // If we know the value is a constant, evaluate the conditional. | |||
| 1677 | Constant *Res = nullptr; | |||
| 1678 | if (Val.isConstant()) { | |||
| 1679 | Res = ConstantFoldCompareInstOperands(Pred, Val.getConstant(), C, DL, TLI); | |||
| 1680 | if (ConstantInt *ResCI = dyn_cast<ConstantInt>(Res)) | |||
| 1681 | return ResCI->isZero() ? LazyValueInfo::False : LazyValueInfo::True; | |||
| 1682 | return LazyValueInfo::Unknown; | |||
| 1683 | } | |||
| 1684 | ||||
| 1685 | if (Val.isConstantRange()) { | |||
| 1686 | ConstantInt *CI = dyn_cast<ConstantInt>(C); | |||
| 1687 | if (!CI) return LazyValueInfo::Unknown; | |||
| 1688 | ||||
| 1689 | const ConstantRange &CR = Val.getConstantRange(); | |||
| 1690 | if (Pred == ICmpInst::ICMP_EQ) { | |||
| 1691 | if (!CR.contains(CI->getValue())) | |||
| 1692 | return LazyValueInfo::False; | |||
| 1693 | ||||
| 1694 | if (CR.isSingleElement()) | |||
| 1695 | return LazyValueInfo::True; | |||
| 1696 | } else if (Pred == ICmpInst::ICMP_NE) { | |||
| 1697 | if (!CR.contains(CI->getValue())) | |||
| 1698 | return LazyValueInfo::True; | |||
| 1699 | ||||
| 1700 | if (CR.isSingleElement()) | |||
| 1701 | return LazyValueInfo::False; | |||
| 1702 | } else { | |||
| 1703 | // Handle more complex predicates. | |||
| 1704 | ConstantRange TrueValues = ConstantRange::makeExactICmpRegion( | |||
| 1705 | (ICmpInst::Predicate)Pred, CI->getValue()); | |||
| 1706 | if (TrueValues.contains(CR)) | |||
| 1707 | return LazyValueInfo::True; | |||
| 1708 | if (TrueValues.inverse().contains(CR)) | |||
| 1709 | return LazyValueInfo::False; | |||
| 1710 | } | |||
| 1711 | return LazyValueInfo::Unknown; | |||
| 1712 | } | |||
| 1713 | ||||
| 1714 | if (Val.isNotConstant()) { | |||
| 1715 | // If this is an equality comparison, we can try to fold it knowing that | |||
| 1716 | // "V != C1". | |||
| 1717 | if (Pred == ICmpInst::ICMP_EQ) { | |||
| 1718 | // !C1 == C -> false iff C1 == C. | |||
| 1719 | Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE, | |||
| 1720 | Val.getNotConstant(), C, DL, | |||
| 1721 | TLI); | |||
| 1722 | if (Res->isNullValue()) | |||
| 1723 | return LazyValueInfo::False; | |||
| 1724 | } else if (Pred == ICmpInst::ICMP_NE) { | |||
| 1725 | // !C1 != C -> true iff C1 == C. | |||
| 1726 | Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE, | |||
| 1727 | Val.getNotConstant(), C, DL, | |||
| 1728 | TLI); | |||
| 1729 | if (Res->isNullValue()) | |||
| 1730 | return LazyValueInfo::True; | |||
| 1731 | } | |||
| 1732 | return LazyValueInfo::Unknown; | |||
| 1733 | } | |||
| 1734 | ||||
| 1735 | return LazyValueInfo::Unknown; | |||
| 1736 | } | |||
| 1737 | ||||
| 1738 | /// Determine whether the specified value comparison with a constant is known to | |||
| 1739 | /// be true or false on the specified CFG edge. Pred is a CmpInst predicate. | |||
| 1740 | LazyValueInfo::Tristate | |||
| 1741 | LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, | |||
| 1742 | BasicBlock *FromBB, BasicBlock *ToBB, | |||
| 1743 | Instruction *CxtI) { | |||
| 1744 | Module *M = FromBB->getModule(); | |||
| 1745 | ValueLatticeElement Result = | |||
| 1746 | getImpl(PImpl, AC, M).getValueOnEdge(V, FromBB, ToBB, CxtI); | |||
| 1747 | ||||
| 1748 | return getPredicateResult(Pred, C, Result, M->getDataLayout(), TLI); | |||
| 1749 | } | |||
| 1750 | ||||
| 1751 | LazyValueInfo::Tristate | |||
| 1752 | LazyValueInfo::getPredicateAt(unsigned Pred, Value *V, Constant *C, | |||
| 1753 | Instruction *CxtI, bool UseBlockValue) { | |||
| 1754 | // Is or is not NonNull are common predicates being queried. If | |||
| 1755 | // isKnownNonZero can tell us the result of the predicate, we can | |||
| 1756 | // return it quickly. But this is only a fastpath, and falling | |||
| 1757 | // through would still be correct. | |||
| 1758 | Module *M = CxtI->getModule(); | |||
| 1759 | const DataLayout &DL = M->getDataLayout(); | |||
| 1760 | if (V->getType()->isPointerTy() && C->isNullValue() && | |||
| 1761 | isKnownNonZero(V->stripPointerCastsSameRepresentation(), DL)) { | |||
| 1762 | if (Pred == ICmpInst::ICMP_EQ) | |||
| 1763 | return LazyValueInfo::False; | |||
| 1764 | else if (Pred == ICmpInst::ICMP_NE) | |||
| 1765 | return LazyValueInfo::True; | |||
| 1766 | } | |||
| 1767 | ||||
| 1768 | ValueLatticeElement Result = UseBlockValue | |||
| 1769 | ? getImpl(PImpl, AC, M).getValueInBlock(V, CxtI->getParent(), CxtI) | |||
| 1770 | : getImpl(PImpl, AC, M).getValueAt(V, CxtI); | |||
| 1771 | Tristate Ret = getPredicateResult(Pred, C, Result, DL, TLI); | |||
| 1772 | if (Ret != Unknown) | |||
| 1773 | return Ret; | |||
| 1774 | ||||
| 1775 | // Note: The following bit of code is somewhat distinct from the rest of LVI; | |||
| 1776 | // LVI as a whole tries to compute a lattice value which is conservatively | |||
| 1777 | // correct at a given location. In this case, we have a predicate which we | |||
| 1778 | // weren't able to prove about the merged result, and we're pushing that | |||
| 1779 | // predicate back along each incoming edge to see if we can prove it | |||
| 1780 | // separately for each input. As a motivating example, consider: | |||
| 1781 | // bb1: | |||
| 1782 | // %v1 = ... ; constantrange<1, 5> | |||
| 1783 | // br label %merge | |||
| 1784 | // bb2: | |||
| 1785 | // %v2 = ... ; constantrange<10, 20> | |||
| 1786 | // br label %merge | |||
| 1787 | // merge: | |||
| 1788 | // %phi = phi [%v1, %v2] ; constantrange<1,20> | |||
| 1789 | // %pred = icmp eq i32 %phi, 8 | |||
| 1790 | // We can't tell from the lattice value for '%phi' that '%pred' is false | |||
| 1791 | // along each path, but by checking the predicate over each input separately, | |||
| 1792 | // we can. | |||
| 1793 | // We limit the search to one step backwards from the current BB and value. | |||
| 1794 | // We could consider extending this to search further backwards through the | |||
| 1795 | // CFG and/or value graph, but there are non-obvious compile time vs quality | |||
| 1796 | // tradeoffs. | |||
| 1797 | BasicBlock *BB = CxtI->getParent(); | |||
| 1798 | ||||
| 1799 | // Function entry or an unreachable block. Bail to avoid confusing | |||
| 1800 | // analysis below. | |||
| 1801 | pred_iterator PI = pred_begin(BB), PE = pred_end(BB); | |||
| 1802 | if (PI == PE) | |||
| 1803 | return Unknown; | |||
| 1804 | ||||
| 1805 | // If V is a PHI node in the same block as the context, we need to ask | |||
| 1806 | // questions about the predicate as applied to the incoming value along | |||
| 1807 | // each edge. This is useful for eliminating cases where the predicate is | |||
| 1808 | // known along all incoming edges. | |||
| 1809 | if (auto *PHI = dyn_cast<PHINode>(V)) | |||
| 1810 | if (PHI->getParent() == BB) { | |||
| 1811 | Tristate Baseline = Unknown; | |||
| 1812 | for (unsigned i = 0, e = PHI->getNumIncomingValues(); i < e; i++) { | |||
| 1813 | Value *Incoming = PHI->getIncomingValue(i); | |||
| 1814 | BasicBlock *PredBB = PHI->getIncomingBlock(i); | |||
| 1815 | // Note that PredBB may be BB itself. | |||
| 1816 | Tristate Result = | |||
| 1817 | getPredicateOnEdge(Pred, Incoming, C, PredBB, BB, CxtI); | |||
| 1818 | ||||
| 1819 | // Keep going as long as we've seen a consistent known result for | |||
| 1820 | // all inputs. | |||
| 1821 | Baseline = (i == 0) ? Result /* First iteration */ | |||
| 1822 | : (Baseline == Result ? Baseline | |||
| 1823 | : Unknown); /* All others */ | |||
| 1824 | if (Baseline == Unknown) | |||
| 1825 | break; | |||
| 1826 | } | |||
| 1827 | if (Baseline != Unknown) | |||
| 1828 | return Baseline; | |||
| 1829 | } | |||
| 1830 | ||||
| 1831 | // For a comparison where the V is outside this block, it's possible | |||
| 1832 | // that we've branched on it before. Look to see if the value is known | |||
| 1833 | // on all incoming edges. | |||
| 1834 | if (!isa<Instruction>(V) || cast<Instruction>(V)->getParent() != BB) { | |||
| 1835 | // For predecessor edge, determine if the comparison is true or false | |||
| 1836 | // on that edge. If they're all true or all false, we can conclude | |||
| 1837 | // the value of the comparison in this block. | |||
| 1838 | Tristate Baseline = getPredicateOnEdge(Pred, V, C, *PI, BB, CxtI); | |||
| 1839 | if (Baseline != Unknown) { | |||
| 1840 | // Check that all remaining incoming values match the first one. | |||
| 1841 | while (++PI != PE) { | |||
| 1842 | Tristate Ret = getPredicateOnEdge(Pred, V, C, *PI, BB, CxtI); | |||
| 1843 | if (Ret != Baseline) | |||
| 1844 | break; | |||
| 1845 | } | |||
| 1846 | // If we terminated early, then one of the values didn't match. | |||
| 1847 | if (PI == PE) { | |||
| 1848 | return Baseline; | |||
| 1849 | } | |||
| 1850 | } | |||
| 1851 | } | |||
| 1852 | ||||
| 1853 | return Unknown; | |||
| 1854 | } | |||
| 1855 | ||||
| 1856 | LazyValueInfo::Tristate LazyValueInfo::getPredicateAt(unsigned P, Value *LHS, | |||
| 1857 | Value *RHS, | |||
| 1858 | Instruction *CxtI, | |||
| 1859 | bool UseBlockValue) { | |||
| 1860 | CmpInst::Predicate Pred = (CmpInst::Predicate)P; | |||
| 1861 | ||||
| 1862 | if (auto *C = dyn_cast<Constant>(RHS)) | |||
| 1863 | return getPredicateAt(P, LHS, C, CxtI, UseBlockValue); | |||
| 1864 | if (auto *C = dyn_cast<Constant>(LHS)) | |||
| 1865 | return getPredicateAt(CmpInst::getSwappedPredicate(Pred), RHS, C, CxtI, | |||
| 1866 | UseBlockValue); | |||
| 1867 | ||||
| 1868 | // Got two non-Constant values. While we could handle them somewhat, | |||
| 1869 | // by getting their constant ranges, and applying ConstantRange::icmp(), | |||
| 1870 | // so far it did not appear to be profitable. | |||
| 1871 | return LazyValueInfo::Unknown; | |||
| 1872 | } | |||
| 1873 | ||||
| 1874 | void LazyValueInfo::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc, | |||
| 1875 | BasicBlock *NewSucc) { | |||
| 1876 | if (PImpl) { | |||
| 1877 | getImpl(PImpl, AC, PredBB->getModule()) | |||
| 1878 | .threadEdge(PredBB, OldSucc, NewSucc); | |||
| 1879 | } | |||
| 1880 | } | |||
| 1881 | ||||
| 1882 | void LazyValueInfo::eraseBlock(BasicBlock *BB) { | |||
| 1883 | if (PImpl) { | |||
| 1884 | getImpl(PImpl, AC, BB->getModule()).eraseBlock(BB); | |||
| 1885 | } | |||
| 1886 | } | |||
| 1887 | ||||
| 1888 | void LazyValueInfo::clear(const Module *M) { | |||
| 1889 | if (PImpl) { | |||
| 1890 | getImpl(PImpl, AC, M).clear(); | |||
| 1891 | } | |||
| 1892 | } | |||
| 1893 | ||||
| 1894 | void LazyValueInfo::printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS) { | |||
| 1895 | if (PImpl) { | |||
| 1896 | getImpl(PImpl, AC, F.getParent()).printLVI(F, DTree, OS); | |||
| 1897 | } | |||
| 1898 | } | |||
| 1899 | ||||
| 1900 | // Print the LVI for the function arguments at the start of each basic block. | |||
| 1901 | void LazyValueInfoAnnotatedWriter::emitBasicBlockStartAnnot( | |||
| 1902 | const BasicBlock *BB, formatted_raw_ostream &OS) { | |||
| 1903 | // Find if there are latticevalues defined for arguments of the function. | |||
| 1904 | auto *F = BB->getParent(); | |||
| 1905 | for (auto &Arg : F->args()) { | |||
| 1906 | ValueLatticeElement Result = LVIImpl->getValueInBlock( | |||
| 1907 | const_cast<Argument *>(&Arg), const_cast<BasicBlock *>(BB)); | |||
| 1908 | if (Result.isUnknown()) | |||
| 1909 | continue; | |||
| 1910 | OS << "; LatticeVal for: '" << Arg << "' is: " << Result << "\n"; | |||
| 1911 | } | |||
| 1912 | } | |||
| 1913 | ||||
| 1914 | // This function prints the LVI analysis for the instruction I at the beginning | |||
| 1915 | // of various basic blocks. It relies on calculated values that are stored in | |||
| 1916 | // the LazyValueInfoCache, and in the absence of cached values, recalculate the | |||
| 1917 | // LazyValueInfo for `I`, and print that info. | |||
| 1918 | void LazyValueInfoAnnotatedWriter::emitInstructionAnnot( | |||
| 1919 | const Instruction *I, formatted_raw_ostream &OS) { | |||
| 1920 | ||||
| 1921 | auto *ParentBB = I->getParent(); | |||
| 1922 | SmallPtrSet<const BasicBlock*, 16> BlocksContainingLVI; | |||
| 1923 | // We can generate (solve) LVI values only for blocks that are dominated by | |||
| 1924 | // the I's parent. However, to avoid generating LVI for all dominating blocks, | |||
| 1925 | // that contain redundant/uninteresting information, we print LVI for | |||
| 1926 | // blocks that may use this LVI information (such as immediate successor | |||
| 1927 | // blocks, and blocks that contain uses of `I`). | |||
| 1928 | auto printResult = [&](const BasicBlock *BB) { | |||
| 1929 | if (!BlocksContainingLVI.insert(BB).second) | |||
| 1930 | return; | |||
| 1931 | ValueLatticeElement Result = LVIImpl->getValueInBlock( | |||
| 1932 | const_cast<Instruction *>(I), const_cast<BasicBlock *>(BB)); | |||
| 1933 | OS << "; LatticeVal for: '" << *I << "' in BB: '"; | |||
| 1934 | BB->printAsOperand(OS, false); | |||
| 1935 | OS << "' is: " << Result << "\n"; | |||
| 1936 | }; | |||
| 1937 | ||||
| 1938 | printResult(ParentBB); | |||
| 1939 | // Print the LVI analysis results for the immediate successor blocks, that | |||
| 1940 | // are dominated by `ParentBB`. | |||
| 1941 | for (auto *BBSucc : successors(ParentBB)) | |||
| 1942 | if (DT.dominates(ParentBB, BBSucc)) | |||
| 1943 | printResult(BBSucc); | |||
| 1944 | ||||
| 1945 | // Print LVI in blocks where `I` is used. | |||
| 1946 | for (auto *U : I->users()) | |||
| 1947 | if (auto *UseI = dyn_cast<Instruction>(U)) | |||
| 1948 | if (!isa<PHINode>(UseI) || DT.dominates(ParentBB, UseI->getParent())) | |||
| 1949 | printResult(UseI->getParent()); | |||
| 1950 | ||||
| 1951 | } | |||
| 1952 | ||||
| 1953 | namespace { | |||
| 1954 | // Printer class for LazyValueInfo results. | |||
| 1955 | class LazyValueInfoPrinter : public FunctionPass { | |||
| 1956 | public: | |||
| 1957 | static char ID; // Pass identification, replacement for typeid | |||
| 1958 | LazyValueInfoPrinter() : FunctionPass(ID) { | |||
| 1959 | initializeLazyValueInfoPrinterPass(*PassRegistry::getPassRegistry()); | |||
| 1960 | } | |||
| 1961 | ||||
| 1962 | void getAnalysisUsage(AnalysisUsage &AU) const override { | |||
| 1963 | AU.setPreservesAll(); | |||
| 1964 | AU.addRequired<LazyValueInfoWrapperPass>(); | |||
| 1965 | AU.addRequired<DominatorTreeWrapperPass>(); | |||
| 1966 | } | |||
| 1967 | ||||
| 1968 | // Get the mandatory dominator tree analysis and pass this in to the | |||
| 1969 | // LVIPrinter. We cannot rely on the LVI's DT, since it's optional. | |||
| 1970 | bool runOnFunction(Function &F) override { | |||
| 1971 | dbgs() << "LVI for function '" << F.getName() << "':\n"; | |||
| 1972 | auto &LVI = getAnalysis<LazyValueInfoWrapperPass>().getLVI(); | |||
| 1973 | auto &DTree = getAnalysis<DominatorTreeWrapperPass>().getDomTree(); | |||
| 1974 | LVI.printLVI(F, DTree, dbgs()); | |||
| 1975 | return false; | |||
| 1976 | } | |||
| 1977 | }; | |||
| 1978 | } | |||
| 1979 | ||||
| 1980 | char LazyValueInfoPrinter::ID = 0; | |||
| 1981 | INITIALIZE_PASS_BEGIN(LazyValueInfoPrinter, "print-lazy-value-info",static void *initializeLazyValueInfoPrinterPassOnce(PassRegistry &Registry) { | |||
| 1982 | "Lazy Value Info Printer Pass", false, false)static void *initializeLazyValueInfoPrinterPassOnce(PassRegistry &Registry) { | |||
| 1983 | INITIALIZE_PASS_DEPENDENCY(LazyValueInfoWrapperPass)initializeLazyValueInfoWrapperPassPass(Registry); | |||
| 1984 | INITIALIZE_PASS_END(LazyValueInfoPrinter, "print-lazy-value-info",PassInfo *PI = new PassInfo( "Lazy Value Info Printer Pass", "print-lazy-value-info" , &LazyValueInfoPrinter::ID, PassInfo::NormalCtor_t(callDefaultCtor <LazyValueInfoPrinter>), false, false); Registry.registerPass (*PI, true); return PI; } static llvm::once_flag InitializeLazyValueInfoPrinterPassFlag ; void llvm::initializeLazyValueInfoPrinterPass(PassRegistry & Registry) { llvm::call_once(InitializeLazyValueInfoPrinterPassFlag , initializeLazyValueInfoPrinterPassOnce, std::ref(Registry)) ; } | |||
| 1985 | "Lazy Value Info Printer Pass", false, false)PassInfo *PI = new PassInfo( "Lazy Value Info Printer Pass", "print-lazy-value-info" , &LazyValueInfoPrinter::ID, PassInfo::NormalCtor_t(callDefaultCtor <LazyValueInfoPrinter>), false, false); Registry.registerPass (*PI, true); return PI; } static llvm::once_flag InitializeLazyValueInfoPrinterPassFlag ; void llvm::initializeLazyValueInfoPrinterPass(PassRegistry & Registry) { llvm::call_once(InitializeLazyValueInfoPrinterPassFlag , initializeLazyValueInfoPrinterPassOnce, std::ref(Registry)) ; } |
| 1 | //===- ValueLattice.h - Value constraint analysis ---------------*- C++ -*-===// | |||
| 2 | // | |||
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. | |||
| 4 | // See https://llvm.org/LICENSE.txt for license information. | |||
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | |||
| 6 | // | |||
| 7 | //===----------------------------------------------------------------------===// | |||
| 8 | ||||
| 9 | #ifndef LLVM_ANALYSIS_VALUELATTICE_H | |||
| 10 | #define LLVM_ANALYSIS_VALUELATTICE_H | |||
| 11 | ||||
| 12 | #include "llvm/IR/Constants.h" | |||
| 13 | #include "llvm/IR/ConstantRange.h" | |||
| 14 | #include "llvm/IR/Instructions.h" | |||
| 15 | ||||
| 16 | //===----------------------------------------------------------------------===// | |||
| 17 | // ValueLatticeElement | |||
| 18 | //===----------------------------------------------------------------------===// | |||
| 19 | ||||
| 20 | namespace llvm { | |||
| 21 | ||||
| 22 | class Constant; | |||
| 23 | ||||
| 24 | /// This class represents lattice values for constants. | |||
| 25 | /// | |||
| 26 | /// FIXME: This is basically just for bringup, this can be made a lot more rich | |||
| 27 | /// in the future. | |||
| 28 | /// | |||
| 29 | class ValueLatticeElement { | |||
| 30 | enum ValueLatticeElementTy { | |||
| 31 | /// This Value has no known value yet. As a result, this implies the | |||
| 32 | /// producing instruction is dead. Caution: We use this as the starting | |||
| 33 | /// state in our local meet rules. In this usage, it's taken to mean | |||
| 34 | /// "nothing known yet". | |||
| 35 | /// Transition to any other state allowed. | |||
| 36 | unknown, | |||
| 37 | ||||
| 38 | /// This Value is an UndefValue constant or produces undef. Undefined values | |||
| 39 | /// can be merged with constants (or single element constant ranges), | |||
| 40 | /// assuming all uses of the result will be replaced. | |||
| 41 | /// Transition allowed to the following states: | |||
| 42 | /// constant | |||
| 43 | /// constantrange_including_undef | |||
| 44 | /// overdefined | |||
| 45 | undef, | |||
| 46 | ||||
| 47 | /// This Value has a specific constant value. The constant cannot be undef. | |||
| 48 | /// (For constant integers, constantrange is used instead. Integer typed | |||
| 49 | /// constantexprs can appear as constant.) Note that the constant state | |||
| 50 | /// can be reached by merging undef & constant states. | |||
| 51 | /// Transition allowed to the following states: | |||
| 52 | /// overdefined | |||
| 53 | constant, | |||
| 54 | ||||
| 55 | /// This Value is known to not have the specified value. (For constant | |||
| 56 | /// integers, constantrange is used instead. As above, integer typed | |||
| 57 | /// constantexprs can appear here.) | |||
| 58 | /// Transition allowed to the following states: | |||
| 59 | /// overdefined | |||
| 60 | notconstant, | |||
| 61 | ||||
| 62 | /// The Value falls within this range. (Used only for integer typed values.) | |||
| 63 | /// Transition allowed to the following states: | |||
| 64 | /// constantrange (new range must be a superset of the existing range) | |||
| 65 | /// constantrange_including_undef | |||
| 66 | /// overdefined | |||
| 67 | constantrange, | |||
| 68 | ||||
| 69 | /// This Value falls within this range, but also may be undef. | |||
| 70 | /// Merging it with other constant ranges results in | |||
| 71 | /// constantrange_including_undef. | |||
| 72 | /// Transition allowed to the following states: | |||
| 73 | /// overdefined | |||
| 74 | constantrange_including_undef, | |||
| 75 | ||||
| 76 | /// We can not precisely model the dynamic values this value might take. | |||
| 77 | /// No transitions are allowed after reaching overdefined. | |||
| 78 | overdefined, | |||
| 79 | }; | |||
| 80 | ||||
| 81 | ValueLatticeElementTy Tag : 8; | |||
| 82 | /// Number of times a constant range has been extended with widening enabled. | |||
| 83 | unsigned NumRangeExtensions : 8; | |||
| 84 | ||||
| 85 | /// The union either stores a pointer to a constant or a constant range, | |||
| 86 | /// associated to the lattice element. We have to ensure that Range is | |||
| 87 | /// initialized or destroyed when changing state to or from constantrange. | |||
| 88 | union { | |||
| 89 | Constant *ConstVal; | |||
| 90 | ConstantRange Range; | |||
| 91 | }; | |||
| 92 | ||||
| 93 | /// Destroy contents of lattice value, without destructing the object. | |||
| 94 | void destroy() { | |||
| 95 | switch (Tag) { | |||
| 96 | case overdefined: | |||
| 97 | case unknown: | |||
| 98 | case undef: | |||
| 99 | case constant: | |||
| 100 | case notconstant: | |||
| 101 | break; | |||
| 102 | case constantrange_including_undef: | |||
| 103 | case constantrange: | |||
| 104 | Range.~ConstantRange(); | |||
| 105 | break; | |||
| 106 | }; | |||
| 107 | } | |||
| 108 | ||||
| 109 | public: | |||
| 110 | /// Struct to control some aspects related to merging constant ranges. | |||
| 111 | struct MergeOptions { | |||
| 112 | /// The merge value may include undef. | |||
| 113 | bool MayIncludeUndef; | |||
| 114 | ||||
| 115 | /// Handle repeatedly extending a range by going to overdefined after a | |||
| 116 | /// number of steps. | |||
| 117 | bool CheckWiden; | |||
| 118 | ||||
| 119 | /// The number of allowed widening steps (including setting the range | |||
| 120 | /// initially). | |||
| 121 | unsigned MaxWidenSteps; | |||
| 122 | ||||
| 123 | MergeOptions() : MergeOptions(false, false) {} | |||
| 124 | ||||
| 125 | MergeOptions(bool MayIncludeUndef, bool CheckWiden, | |||
| 126 | unsigned MaxWidenSteps = 1) | |||
| 127 | : MayIncludeUndef(MayIncludeUndef), CheckWiden(CheckWiden), | |||
| 128 | MaxWidenSteps(MaxWidenSteps) {} | |||
| 129 | ||||
| 130 | MergeOptions &setMayIncludeUndef(bool V = true) { | |||
| 131 | MayIncludeUndef = V; | |||
| 132 | return *this; | |||
| 133 | } | |||
| 134 | ||||
| 135 | MergeOptions &setCheckWiden(bool V = true) { | |||
| 136 | CheckWiden = V; | |||
| 137 | return *this; | |||
| 138 | } | |||
| 139 | ||||
| 140 | MergeOptions &setMaxWidenSteps(unsigned Steps = 1) { | |||
| 141 | CheckWiden = true; | |||
| 142 | MaxWidenSteps = Steps; | |||
| 143 | return *this; | |||
| 144 | } | |||
| 145 | }; | |||
| 146 | ||||
| 147 | // ConstVal and Range are initialized on-demand. | |||
| 148 | ValueLatticeElement() : Tag(unknown), NumRangeExtensions(0) {} | |||
| 149 | ||||
| 150 | ~ValueLatticeElement() { destroy(); } | |||
| 151 | ||||
| 152 | ValueLatticeElement(const ValueLatticeElement &Other) | |||
| 153 | : Tag(Other.Tag), NumRangeExtensions(0) { | |||
| 154 | switch (Other.Tag) { | |||
| 155 | case constantrange: | |||
| 156 | case constantrange_including_undef: | |||
| 157 | new (&Range) ConstantRange(Other.Range); | |||
| 158 | NumRangeExtensions = Other.NumRangeExtensions; | |||
| 159 | break; | |||
| 160 | case constant: | |||
| 161 | case notconstant: | |||
| 162 | ConstVal = Other.ConstVal; | |||
| 163 | break; | |||
| 164 | case overdefined: | |||
| 165 | case unknown: | |||
| 166 | case undef: | |||
| 167 | break; | |||
| 168 | } | |||
| 169 | } | |||
| 170 | ||||
| 171 | ValueLatticeElement(ValueLatticeElement &&Other) | |||
| 172 | : Tag(Other.Tag), NumRangeExtensions(0) { | |||
| 173 | switch (Other.Tag) { | |||
| 174 | case constantrange: | |||
| 175 | case constantrange_including_undef: | |||
| 176 | new (&Range) ConstantRange(std::move(Other.Range)); | |||
| 177 | NumRangeExtensions = Other.NumRangeExtensions; | |||
| 178 | break; | |||
| 179 | case constant: | |||
| 180 | case notconstant: | |||
| 181 | ConstVal = Other.ConstVal; | |||
| 182 | break; | |||
| 183 | case overdefined: | |||
| 184 | case unknown: | |||
| 185 | case undef: | |||
| 186 | break; | |||
| 187 | } | |||
| 188 | Other.Tag = unknown; | |||
| 189 | } | |||
| 190 | ||||
| 191 | ValueLatticeElement &operator=(const ValueLatticeElement &Other) { | |||
| 192 | destroy(); | |||
| 193 | new (this) ValueLatticeElement(Other); | |||
| 194 | return *this; | |||
| 195 | } | |||
| 196 | ||||
| 197 | ValueLatticeElement &operator=(ValueLatticeElement &&Other) { | |||
| 198 | destroy(); | |||
| 199 | new (this) ValueLatticeElement(std::move(Other)); | |||
| 200 | return *this; | |||
| 201 | } | |||
| 202 | ||||
| 203 | static ValueLatticeElement get(Constant *C) { | |||
| 204 | ValueLatticeElement Res; | |||
| 205 | if (isa<UndefValue>(C)) | |||
| 206 | Res.markUndef(); | |||
| 207 | else | |||
| 208 | Res.markConstant(C); | |||
| 209 | return Res; | |||
| 210 | } | |||
| 211 | static ValueLatticeElement getNot(Constant *C) { | |||
| 212 | ValueLatticeElement Res; | |||
| 213 | assert(!isa<UndefValue>(C) && "!= undef is not supported")(static_cast <bool> (!isa<UndefValue>(C) && "!= undef is not supported") ? void (0) : __assert_fail ("!isa<UndefValue>(C) && \"!= undef is not supported\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 213, __extension__ __PRETTY_FUNCTION__)); | |||
| 214 | Res.markNotConstant(C); | |||
| 215 | return Res; | |||
| 216 | } | |||
| 217 | static ValueLatticeElement getRange(ConstantRange CR, | |||
| 218 | bool MayIncludeUndef = false) { | |||
| 219 | if (CR.isFullSet()) | |||
| 220 | return getOverdefined(); | |||
| 221 | ||||
| 222 | if (CR.isEmptySet()) { | |||
| 223 | ValueLatticeElement Res; | |||
| 224 | if (MayIncludeUndef) | |||
| 225 | Res.markUndef(); | |||
| 226 | return Res; | |||
| 227 | } | |||
| 228 | ||||
| 229 | ValueLatticeElement Res; | |||
| 230 | Res.markConstantRange(std::move(CR), | |||
| 231 | MergeOptions().setMayIncludeUndef(MayIncludeUndef)); | |||
| 232 | return Res; | |||
| 233 | } | |||
| 234 | static ValueLatticeElement getOverdefined() { | |||
| 235 | ValueLatticeElement Res; | |||
| 236 | Res.markOverdefined(); | |||
| 237 | return Res; | |||
| 238 | } | |||
| 239 | ||||
| 240 | bool isUndef() const { return Tag == undef; } | |||
| 241 | bool isUnknown() const { return Tag == unknown; } | |||
| 242 | bool isUnknownOrUndef() const { return Tag == unknown || Tag == undef; } | |||
| 243 | bool isConstant() const { return Tag == constant; } | |||
| 244 | bool isNotConstant() const { return Tag == notconstant; } | |||
| 245 | bool isConstantRangeIncludingUndef() const { | |||
| 246 | return Tag == constantrange_including_undef; | |||
| 247 | } | |||
| 248 | /// Returns true if this value is a constant range. Use \p UndefAllowed to | |||
| 249 | /// exclude non-singleton constant ranges that may also be undef. Note that | |||
| 250 | /// this function also returns true if the range may include undef, but only | |||
| 251 | /// contains a single element. In that case, it can be replaced by a constant. | |||
| 252 | bool isConstantRange(bool UndefAllowed = true) const { | |||
| 253 | return Tag == constantrange || (Tag == constantrange_including_undef && | |||
| 254 | (UndefAllowed || Range.isSingleElement())); | |||
| 255 | } | |||
| 256 | bool isOverdefined() const { return Tag == overdefined; } | |||
| 257 | ||||
| 258 | Constant *getConstant() const { | |||
| 259 | assert(isConstant() && "Cannot get the constant of a non-constant!")(static_cast <bool> (isConstant() && "Cannot get the constant of a non-constant!" ) ? void (0) : __assert_fail ("isConstant() && \"Cannot get the constant of a non-constant!\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 259, __extension__ __PRETTY_FUNCTION__)); | |||
| 260 | return ConstVal; | |||
| ||||
| 261 | } | |||
| 262 | ||||
| 263 | Constant *getNotConstant() const { | |||
| 264 | assert(isNotConstant() && "Cannot get the constant of a non-notconstant!")(static_cast <bool> (isNotConstant() && "Cannot get the constant of a non-notconstant!" ) ? void (0) : __assert_fail ("isNotConstant() && \"Cannot get the constant of a non-notconstant!\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 264, __extension__ __PRETTY_FUNCTION__)); | |||
| 265 | return ConstVal; | |||
| 266 | } | |||
| 267 | ||||
| 268 | /// Returns the constant range for this value. Use \p UndefAllowed to exclude | |||
| 269 | /// non-singleton constant ranges that may also be undef. Note that this | |||
| 270 | /// function also returns a range if the range may include undef, but only | |||
| 271 | /// contains a single element. In that case, it can be replaced by a constant. | |||
| 272 | const ConstantRange &getConstantRange(bool UndefAllowed = true) const { | |||
| 273 | assert(isConstantRange(UndefAllowed) &&(static_cast <bool> (isConstantRange(UndefAllowed) && "Cannot get the constant-range of a non-constant-range!") ? void (0) : __assert_fail ("isConstantRange(UndefAllowed) && \"Cannot get the constant-range of a non-constant-range!\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 274, __extension__ __PRETTY_FUNCTION__)) | |||
| 274 | "Cannot get the constant-range of a non-constant-range!")(static_cast <bool> (isConstantRange(UndefAllowed) && "Cannot get the constant-range of a non-constant-range!") ? void (0) : __assert_fail ("isConstantRange(UndefAllowed) && \"Cannot get the constant-range of a non-constant-range!\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 274, __extension__ __PRETTY_FUNCTION__)); | |||
| 275 | return Range; | |||
| 276 | } | |||
| 277 | ||||
| 278 | Optional<APInt> asConstantInteger() const { | |||
| 279 | if (isConstant() && isa<ConstantInt>(getConstant())) { | |||
| 280 | return cast<ConstantInt>(getConstant())->getValue(); | |||
| 281 | } else if (isConstantRange() && getConstantRange().isSingleElement()) { | |||
| 282 | return *getConstantRange().getSingleElement(); | |||
| 283 | } | |||
| 284 | return None; | |||
| 285 | } | |||
| 286 | ||||
| 287 | bool markOverdefined() { | |||
| 288 | if (isOverdefined()) | |||
| 289 | return false; | |||
| 290 | destroy(); | |||
| 291 | Tag = overdefined; | |||
| 292 | return true; | |||
| 293 | } | |||
| 294 | ||||
| 295 | bool markUndef() { | |||
| 296 | if (isUndef()) | |||
| 297 | return false; | |||
| 298 | ||||
| 299 | assert(isUnknown())(static_cast <bool> (isUnknown()) ? void (0) : __assert_fail ("isUnknown()", "llvm/include/llvm/Analysis/ValueLattice.h", 299, __extension__ __PRETTY_FUNCTION__)); | |||
| 300 | Tag = undef; | |||
| 301 | return true; | |||
| 302 | } | |||
| 303 | ||||
| 304 | bool markConstant(Constant *V, bool MayIncludeUndef = false) { | |||
| 305 | if (isa<UndefValue>(V)) | |||
| 306 | return markUndef(); | |||
| 307 | ||||
| 308 | if (isConstant()) { | |||
| 309 | assert(getConstant() == V && "Marking constant with different value")(static_cast <bool> (getConstant() == V && "Marking constant with different value" ) ? void (0) : __assert_fail ("getConstant() == V && \"Marking constant with different value\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 309, __extension__ __PRETTY_FUNCTION__)); | |||
| 310 | return false; | |||
| 311 | } | |||
| 312 | ||||
| 313 | if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) | |||
| 314 | return markConstantRange( | |||
| 315 | ConstantRange(CI->getValue()), | |||
| 316 | MergeOptions().setMayIncludeUndef(MayIncludeUndef)); | |||
| 317 | ||||
| 318 | assert(isUnknown() || isUndef())(static_cast <bool> (isUnknown() || isUndef()) ? void ( 0) : __assert_fail ("isUnknown() || isUndef()", "llvm/include/llvm/Analysis/ValueLattice.h" , 318, __extension__ __PRETTY_FUNCTION__)); | |||
| 319 | Tag = constant; | |||
| 320 | ConstVal = V; | |||
| 321 | return true; | |||
| 322 | } | |||
| 323 | ||||
| 324 | bool markNotConstant(Constant *V) { | |||
| 325 | assert(V && "Marking constant with NULL")(static_cast <bool> (V && "Marking constant with NULL" ) ? void (0) : __assert_fail ("V && \"Marking constant with NULL\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 325, __extension__ __PRETTY_FUNCTION__)); | |||
| 326 | if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) | |||
| 327 | return markConstantRange( | |||
| 328 | ConstantRange(CI->getValue() + 1, CI->getValue())); | |||
| 329 | ||||
| 330 | if (isa<UndefValue>(V)) | |||
| 331 | return false; | |||
| 332 | ||||
| 333 | if (isNotConstant()) { | |||
| 334 | assert(getNotConstant() == V && "Marking !constant with different value")(static_cast <bool> (getNotConstant() == V && "Marking !constant with different value" ) ? void (0) : __assert_fail ("getNotConstant() == V && \"Marking !constant with different value\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 334, __extension__ __PRETTY_FUNCTION__)); | |||
| 335 | return false; | |||
| 336 | } | |||
| 337 | ||||
| 338 | assert(isUnknown())(static_cast <bool> (isUnknown()) ? void (0) : __assert_fail ("isUnknown()", "llvm/include/llvm/Analysis/ValueLattice.h", 338, __extension__ __PRETTY_FUNCTION__)); | |||
| 339 | Tag = notconstant; | |||
| 340 | ConstVal = V; | |||
| 341 | return true; | |||
| 342 | } | |||
| 343 | ||||
| 344 | /// Mark the object as constant range with \p NewR. If the object is already a | |||
| 345 | /// constant range, nothing changes if the existing range is equal to \p | |||
| 346 | /// NewR and the tag. Otherwise \p NewR must be a superset of the existing | |||
| 347 | /// range or the object must be undef. The tag is set to | |||
| 348 | /// constant_range_including_undef if either the existing value or the new | |||
| 349 | /// range may include undef. | |||
| 350 | bool markConstantRange(ConstantRange NewR, | |||
| 351 | MergeOptions Opts = MergeOptions()) { | |||
| 352 | assert(!NewR.isEmptySet() && "should only be called for non-empty sets")(static_cast <bool> (!NewR.isEmptySet() && "should only be called for non-empty sets" ) ? void (0) : __assert_fail ("!NewR.isEmptySet() && \"should only be called for non-empty sets\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 352, __extension__ __PRETTY_FUNCTION__)); | |||
| 353 | ||||
| 354 | if (NewR.isFullSet()) | |||
| 355 | return markOverdefined(); | |||
| 356 | ||||
| 357 | ValueLatticeElementTy OldTag = Tag; | |||
| 358 | ValueLatticeElementTy NewTag = | |||
| 359 | (isUndef() || isConstantRangeIncludingUndef() || Opts.MayIncludeUndef) | |||
| 360 | ? constantrange_including_undef | |||
| 361 | : constantrange; | |||
| 362 | if (isConstantRange()) { | |||
| 363 | Tag = NewTag; | |||
| 364 | if (getConstantRange() == NewR) | |||
| 365 | return Tag != OldTag; | |||
| 366 | ||||
| 367 | // Simple form of widening. If a range is extended multiple times, go to | |||
| 368 | // overdefined. | |||
| 369 | if (Opts.CheckWiden && ++NumRangeExtensions > Opts.MaxWidenSteps) | |||
| 370 | return markOverdefined(); | |||
| 371 | ||||
| 372 | assert(NewR.contains(getConstantRange()) &&(static_cast <bool> (NewR.contains(getConstantRange()) && "Existing range must be a subset of NewR") ? void (0) : __assert_fail ("NewR.contains(getConstantRange()) && \"Existing range must be a subset of NewR\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 373, __extension__ __PRETTY_FUNCTION__)) | |||
| 373 | "Existing range must be a subset of NewR")(static_cast <bool> (NewR.contains(getConstantRange()) && "Existing range must be a subset of NewR") ? void (0) : __assert_fail ("NewR.contains(getConstantRange()) && \"Existing range must be a subset of NewR\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 373, __extension__ __PRETTY_FUNCTION__)); | |||
| 374 | Range = std::move(NewR); | |||
| 375 | return true; | |||
| 376 | } | |||
| 377 | ||||
| 378 | assert(isUnknown() || isUndef())(static_cast <bool> (isUnknown() || isUndef()) ? void ( 0) : __assert_fail ("isUnknown() || isUndef()", "llvm/include/llvm/Analysis/ValueLattice.h" , 378, __extension__ __PRETTY_FUNCTION__)); | |||
| 379 | ||||
| 380 | NumRangeExtensions = 0; | |||
| 381 | Tag = NewTag; | |||
| 382 | new (&Range) ConstantRange(std::move(NewR)); | |||
| 383 | return true; | |||
| 384 | } | |||
| 385 | ||||
| 386 | /// Updates this object to approximate both this object and RHS. Returns | |||
| 387 | /// true if this object has been changed. | |||
| 388 | bool mergeIn(const ValueLatticeElement &RHS, | |||
| 389 | MergeOptions Opts = MergeOptions()) { | |||
| 390 | if (RHS.isUnknown() || isOverdefined()) | |||
| 391 | return false; | |||
| 392 | if (RHS.isOverdefined()) { | |||
| 393 | markOverdefined(); | |||
| 394 | return true; | |||
| 395 | } | |||
| 396 | ||||
| 397 | if (isUndef()) { | |||
| 398 | assert(!RHS.isUnknown())(static_cast <bool> (!RHS.isUnknown()) ? void (0) : __assert_fail ("!RHS.isUnknown()", "llvm/include/llvm/Analysis/ValueLattice.h" , 398, __extension__ __PRETTY_FUNCTION__)); | |||
| 399 | if (RHS.isUndef()) | |||
| 400 | return false; | |||
| 401 | if (RHS.isConstant()) | |||
| 402 | return markConstant(RHS.getConstant(), true); | |||
| 403 | if (RHS.isConstantRange()) | |||
| 404 | return markConstantRange(RHS.getConstantRange(true), | |||
| 405 | Opts.setMayIncludeUndef()); | |||
| 406 | return markOverdefined(); | |||
| 407 | } | |||
| 408 | ||||
| 409 | if (isUnknown()) { | |||
| 410 | assert(!RHS.isUnknown() && "Unknow RHS should be handled earlier")(static_cast <bool> (!RHS.isUnknown() && "Unknow RHS should be handled earlier" ) ? void (0) : __assert_fail ("!RHS.isUnknown() && \"Unknow RHS should be handled earlier\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 410, __extension__ __PRETTY_FUNCTION__)); | |||
| 411 | *this = RHS; | |||
| 412 | return true; | |||
| 413 | } | |||
| 414 | ||||
| 415 | if (isConstant()) { | |||
| 416 | if (RHS.isConstant() && getConstant() == RHS.getConstant()) | |||
| 417 | return false; | |||
| 418 | if (RHS.isUndef()) | |||
| 419 | return false; | |||
| 420 | markOverdefined(); | |||
| 421 | return true; | |||
| 422 | } | |||
| 423 | ||||
| 424 | if (isNotConstant()) { | |||
| 425 | if (RHS.isNotConstant() && getNotConstant() == RHS.getNotConstant()) | |||
| 426 | return false; | |||
| 427 | markOverdefined(); | |||
| 428 | return true; | |||
| 429 | } | |||
| 430 | ||||
| 431 | auto OldTag = Tag; | |||
| 432 | assert(isConstantRange() && "New ValueLattice type?")(static_cast <bool> (isConstantRange() && "New ValueLattice type?" ) ? void (0) : __assert_fail ("isConstantRange() && \"New ValueLattice type?\"" , "llvm/include/llvm/Analysis/ValueLattice.h", 432, __extension__ __PRETTY_FUNCTION__)); | |||
| 433 | if (RHS.isUndef()) { | |||
| 434 | Tag = constantrange_including_undef; | |||
| 435 | return OldTag != Tag; | |||
| 436 | } | |||
| 437 | ||||
| 438 | if (!RHS.isConstantRange()) { | |||
| 439 | // We can get here if we've encountered a constantexpr of integer type | |||
| 440 | // and merge it with a constantrange. | |||
| 441 | markOverdefined(); | |||
| 442 | return true; | |||
| 443 | } | |||
| 444 | ||||
| 445 | ConstantRange NewR = getConstantRange().unionWith(RHS.getConstantRange()); | |||
| 446 | return markConstantRange( | |||
| 447 | std::move(NewR), | |||
| 448 | Opts.setMayIncludeUndef(RHS.isConstantRangeIncludingUndef())); | |||
| 449 | } | |||
| 450 | ||||
| 451 | // Compares this symbolic value with Other using Pred and returns either | |||
| 452 | /// true, false or undef constants, or nullptr if the comparison cannot be | |||
| 453 | /// evaluated. | |||
| 454 | Constant *getCompare(CmpInst::Predicate Pred, Type *Ty, | |||
| 455 | const ValueLatticeElement &Other) const { | |||
| 456 | if (isUnknownOrUndef() || Other.isUnknownOrUndef()) | |||
| 457 | return UndefValue::get(Ty); | |||
| 458 | ||||
| 459 | if (isConstant() && Other.isConstant()) | |||
| 460 | return ConstantExpr::getCompare(Pred, getConstant(), Other.getConstant()); | |||
| 461 | ||||
| 462 | if (ICmpInst::isEquality(Pred)) { | |||
| 463 | // not(C) != C => true, not(C) == C => false. | |||
| 464 | if ((isNotConstant() && Other.isConstant() && | |||
| 465 | getNotConstant() == Other.getConstant()) || | |||
| 466 | (isConstant() && Other.isNotConstant() && | |||
| 467 | getConstant() == Other.getNotConstant())) | |||
| 468 | return Pred == ICmpInst::ICMP_NE | |||
| 469 | ? ConstantInt::getTrue(Ty) : ConstantInt::getFalse(Ty); | |||
| 470 | } | |||
| 471 | ||||
| 472 | // Integer constants are represented as ConstantRanges with single | |||
| 473 | // elements. | |||
| 474 | if (!isConstantRange() || !Other.isConstantRange()) | |||
| 475 | return nullptr; | |||
| 476 | ||||
| 477 | const auto &CR = getConstantRange(); | |||
| 478 | const auto &OtherCR = Other.getConstantRange(); | |||
| 479 | if (CR.icmp(Pred, OtherCR)) | |||
| 480 | return ConstantInt::getTrue(Ty); | |||
| 481 | if (CR.icmp(CmpInst::getInversePredicate(Pred), OtherCR)) | |||
| 482 | return ConstantInt::getFalse(Ty); | |||
| 483 | ||||
| 484 | return nullptr; | |||
| 485 | } | |||
| 486 | ||||
| 487 | unsigned getNumRangeExtensions() const { return NumRangeExtensions; } | |||
| 488 | void setNumRangeExtensions(unsigned N) { NumRangeExtensions = N; } | |||
| 489 | }; | |||
| 490 | ||||
| 491 | static_assert(sizeof(ValueLatticeElement) <= 40, | |||
| 492 | "size of ValueLatticeElement changed unexpectedly"); | |||
| 493 | ||||
| 494 | raw_ostream &operator<<(raw_ostream &OS, const ValueLatticeElement &Val); | |||
| 495 | } // end namespace llvm | |||
| 496 | #endif |