Bug Summary

File:build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/include/llvm/Analysis/ValueLattice.h
Warning:line 181, column 16
Assigned value is garbage or undefined

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name LazyValueInfo.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm -resource-dir /usr/lib/llvm-16/lib/clang/16.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I lib/Analysis -I /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/lib/Analysis -I include -I /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-16/lib/clang/16.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm=build-llvm -fmacro-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/= -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm=build-llvm -fcoverage-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/= -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/build-llvm=build-llvm -fdebug-prefix-map=/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2022-09-04-125545-48738-1 -x c++ /build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/lib/Analysis/LazyValueInfo.cpp

/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/lib/Analysis/LazyValueInfo.cpp

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"
41using namespace llvm;
42using 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.
48static const unsigned MaxProcessedPerValue = 500;
49
50char LazyValueInfoWrapperPass::ID = 0;
51LazyValueInfoWrapperPass::LazyValueInfoWrapperPass() : FunctionPass(ID) {
52 initializeLazyValueInfoWrapperPassPass(*PassRegistry::getPassRegistry());
53}
54INITIALIZE_PASS_BEGIN(LazyValueInfoWrapperPass, "lazy-value-info",static void *initializeLazyValueInfoWrapperPassPassOnce(PassRegistry
&Registry) {
55 "Lazy Value Information Analysis", false, true)static void *initializeLazyValueInfoWrapperPassPassOnce(PassRegistry
&Registry) {
56INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)initializeAssumptionCacheTrackerPass(Registry);
57INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
58INITIALIZE_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
61namespace llvm {
62 FunctionPass *createLazyValueInfoPass() { return new LazyValueInfoWrapperPass(); }
63}
64
65AnalysisKey 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.
70static 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.
95static 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
136namespace {
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
152namespace {
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
262void 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
275void 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
281void LazyValueInfoCache::eraseBlock(BasicBlock *BB) {
282 BlockCache.erase(BB);
283}
284
285void 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
340namespace {
341/// An assembly annotator class to print LazyValueCache information in
342/// comments.
343class LazyValueInfoImpl;
344class 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
350public:
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}
361namespace {
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.
365class 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
436public:
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
483void 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
536Optional<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
556static 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
573bool 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
589Optional<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
633static void AddNonNullPointer(Value *Ptr, NonNullPointerSet &PtrSet) {
634 // TODO: Use NullPointerIsDefined instead.
635 if (Ptr->getType()->getPointerAddressSpace() == 0)
636 PtrSet.insert(getUnderlyingObject(Ptr));
637}
638
639static 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
658bool 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
672Optional<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
714Optional<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
750static 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
755void 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
797static 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
804Optional<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
885Optional<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
894Optional<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)
922 // More work to do before applying this transfer rule.
923 return None;
924 const ConstantRange &LHSRange = LHSRes.value();
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
935Optional<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 || !RHSRes)
946 // More work to do before applying this transfer rule.
947 return None;
948
949 const ConstantRange &LHSRange = LHSRes.value();
950 const ConstantRange &RHSRange = RHSRes.value();
951 return ValueLatticeElement::getRange(OpFn(LHSRange, RHSRange));
952}
953
954Optional<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 (auto *OBO = dyn_cast<OverflowingBinaryOperator>(BO)) {
959 unsigned NoWrapKind = 0;
960 if (OBO->hasNoUnsignedWrap())
961 NoWrapKind |= OverflowingBinaryOperator::NoUnsignedWrap;
962 if (OBO->hasNoSignedWrap())
963 NoWrapKind |= OverflowingBinaryOperator::NoSignedWrap;
964
965 return solveBlockValueBinaryOpImpl(
966 BO, BB,
967 [BO, NoWrapKind](const ConstantRange &CR1, const ConstantRange &CR2) {
968 return CR1.overflowingBinaryOp(BO->getOpcode(), CR2, NoWrapKind);
969 });
970 }
971
972 return solveBlockValueBinaryOpImpl(
973 BO, BB, [BO](const ConstantRange &CR1, const ConstantRange &CR2) {
974 return CR1.binaryOp(BO->getOpcode(), CR2);
975 });
976}
977
978Optional<ValueLatticeElement>
979LazyValueInfoImpl::solveBlockValueOverflowIntrinsic(WithOverflowInst *WO,
980 BasicBlock *BB) {
981 return solveBlockValueBinaryOpImpl(
982 WO, BB, [WO](const ConstantRange &CR1, const ConstantRange &CR2) {
983 return CR1.binaryOp(WO->getBinaryOp(), CR2);
984 });
985}
986
987Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueIntrinsic(
988 IntrinsicInst *II, BasicBlock *BB) {
989 if (!ConstantRange::isIntrinsicSupported(II->getIntrinsicID())) {
990 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)
991 << "' - unknown intrinsic.\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("lazy-value-info")) { dbgs() << " compute BB '" <<
BB->getName() << "' - unknown intrinsic.\n"; } } while
(false)
;
992 return getFromRangeMetadata(II);
993 }
994
995 SmallVector<ConstantRange, 2> OpRanges;
996 for (Value *Op : II->args()) {
997 Optional<ConstantRange> Range = getRangeFor(Op, II, BB);
998 if (!Range)
999 return None;
1000 OpRanges.push_back(*Range);
1001 }
1002
1003 return ValueLatticeElement::getRange(
1004 ConstantRange::intrinsic(II->getIntrinsicID(), OpRanges));
1005}
1006
1007Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueExtractValue(
1008 ExtractValueInst *EVI, BasicBlock *BB) {
1009 if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand()))
1010 if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 0)
1011 return solveBlockValueOverflowIntrinsic(WO, BB);
1012
1013 // Handle extractvalue of insertvalue to allow further simplification
1014 // based on replaced with.overflow intrinsics.
1015 if (Value *V = simplifyExtractValueInst(
1016 EVI->getAggregateOperand(), EVI->getIndices(),
1017 EVI->getModule()->getDataLayout()))
1018 return getBlockValue(V, BB, EVI);
1019
1020 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)
1021 << "' - overdefined (unknown extractvalue).\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("lazy-value-info")) { dbgs() << " compute BB '" <<
BB->getName() << "' - overdefined (unknown extractvalue).\n"
; } } while (false)
;
1022 return ValueLatticeElement::getOverdefined();
1023}
1024
1025static bool matchICmpOperand(APInt &Offset, Value *LHS, Value *Val,
1026 ICmpInst::Predicate Pred) {
1027 if (LHS == Val)
1028 return true;
1029
1030 // Handle range checking idiom produced by InstCombine. We will subtract the
1031 // offset from the allowed range for RHS in this case.
1032 const APInt *C;
1033 if (match(LHS, m_Add(m_Specific(Val), m_APInt(C)))) {
1034 Offset = *C;
1035 return true;
1036 }
1037
1038 // Handle the symmetric case. This appears in saturation patterns like
1039 // (x == 16) ? 16 : (x + 1).
1040 if (match(Val, m_Add(m_Specific(LHS), m_APInt(C)))) {
1041 Offset = -*C;
1042 return true;
1043 }
1044
1045 // If (x | y) < C, then (x < C) && (y < C).
1046 if (match(LHS, m_c_Or(m_Specific(Val), m_Value())) &&
1047 (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE))
1048 return true;
1049
1050 // If (x & y) > C, then (x > C) && (y > C).
1051 if (match(LHS, m_c_And(m_Specific(Val), m_Value())) &&
1052 (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE))
1053 return true;
1054
1055 return false;
1056}
1057
1058/// Get value range for a "(Val + Offset) Pred RHS" condition.
1059static ValueLatticeElement getValueFromSimpleICmpCondition(
1060 CmpInst::Predicate Pred, Value *RHS, const APInt &Offset) {
1061 ConstantRange RHSRange(RHS->getType()->getIntegerBitWidth(),
1062 /*isFullSet=*/true);
1063 if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS))
1064 RHSRange = ConstantRange(CI->getValue());
1065 else if (Instruction *I = dyn_cast<Instruction>(RHS))
1066 if (auto *Ranges = I->getMetadata(LLVMContext::MD_range))
1067 RHSRange = getConstantRangeFromMetadata(*Ranges);
1068
1069 ConstantRange TrueValues =
1070 ConstantRange::makeAllowedICmpRegion(Pred, RHSRange);
1071 return ValueLatticeElement::getRange(TrueValues.subtract(Offset));
1072}
1073
1074static ValueLatticeElement getValueFromICmpCondition(Value *Val, ICmpInst *ICI,
1075 bool isTrueDest) {
1076 Value *LHS = ICI->getOperand(0);
1077 Value *RHS = ICI->getOperand(1);
1078
1079 // Get the predicate that must hold along the considered edge.
1080 CmpInst::Predicate EdgePred =
1081 isTrueDest ? ICI->getPredicate() : ICI->getInversePredicate();
1082
1083 if (isa<Constant>(RHS)) {
1084 if (ICI->isEquality() && LHS == Val) {
1085 if (EdgePred == ICmpInst::ICMP_EQ)
1086 return ValueLatticeElement::get(cast<Constant>(RHS));
1087 else if (!isa<UndefValue>(RHS))
1088 return ValueLatticeElement::getNot(cast<Constant>(RHS));
1089 }
1090 }
1091
1092 Type *Ty = Val->getType();
1093 if (!Ty->isIntegerTy())
1094 return ValueLatticeElement::getOverdefined();
1095
1096 unsigned BitWidth = Ty->getScalarSizeInBits();
1097 APInt Offset(BitWidth, 0);
1098 if (matchICmpOperand(Offset, LHS, Val, EdgePred))
1099 return getValueFromSimpleICmpCondition(EdgePred, RHS, Offset);
1100
1101 CmpInst::Predicate SwappedPred = CmpInst::getSwappedPredicate(EdgePred);
1102 if (matchICmpOperand(Offset, RHS, Val, SwappedPred))
1103 return getValueFromSimpleICmpCondition(SwappedPred, LHS, Offset);
1104
1105 const APInt *Mask, *C;
1106 if (match(LHS, m_And(m_Specific(Val), m_APInt(Mask))) &&
1107 match(RHS, m_APInt(C))) {
1108 // If (Val & Mask) == C then all the masked bits are known and we can
1109 // compute a value range based on that.
1110 if (EdgePred == ICmpInst::ICMP_EQ) {
1111 KnownBits Known;
1112 Known.Zero = ~*C & *Mask;
1113 Known.One = *C & *Mask;
1114 return ValueLatticeElement::getRange(
1115 ConstantRange::fromKnownBits(Known, /*IsSigned*/ false));
1116 }
1117 // If (Val & Mask) != 0 then the value must be larger than the lowest set
1118 // bit of Mask.
1119 if (EdgePred == ICmpInst::ICMP_NE && !Mask->isZero() && C->isZero()) {
1120 return ValueLatticeElement::getRange(ConstantRange::getNonEmpty(
1121 APInt::getOneBitSet(BitWidth, Mask->countTrailingZeros()),
1122 APInt::getZero(BitWidth)));
1123 }
1124 }
1125
1126 // If (X urem Modulus) >= C, then X >= C.
1127 // If trunc X >= C, then X >= C.
1128 // TODO: An upper bound could be computed as well.
1129 if (match(LHS, m_CombineOr(m_URem(m_Specific(Val), m_Value()),
1130 m_Trunc(m_Specific(Val)))) &&
1131 match(RHS, m_APInt(C))) {
1132 // Use the icmp region so we don't have to deal with different predicates.
1133 ConstantRange CR = ConstantRange::makeExactICmpRegion(EdgePred, *C);
1134 if (!CR.isEmptySet())
1135 return ValueLatticeElement::getRange(ConstantRange::getNonEmpty(
1136 CR.getUnsignedMin().zext(BitWidth), APInt(BitWidth, 0)));
1137 }
1138
1139 return ValueLatticeElement::getOverdefined();
1140}
1141
1142// Handle conditions of the form
1143// extractvalue(op.with.overflow(%x, C), 1).
1144static ValueLatticeElement getValueFromOverflowCondition(
1145 Value *Val, WithOverflowInst *WO, bool IsTrueDest) {
1146 // TODO: This only works with a constant RHS for now. We could also compute
1147 // the range of the RHS, but this doesn't fit into the current structure of
1148 // the edge value calculation.
1149 const APInt *C;
1150 if (WO->getLHS() != Val || !match(WO->getRHS(), m_APInt(C)))
1151 return ValueLatticeElement::getOverdefined();
1152
1153 // Calculate the possible values of %x for which no overflow occurs.
1154 ConstantRange NWR = ConstantRange::makeExactNoWrapRegion(
1155 WO->getBinaryOp(), *C, WO->getNoWrapKind());
1156
1157 // If overflow is false, %x is constrained to NWR. If overflow is true, %x is
1158 // constrained to it's inverse (all values that might cause overflow).
1159 if (IsTrueDest)
1160 NWR = NWR.inverse();
1161 return ValueLatticeElement::getRange(NWR);
1162}
1163
1164static Optional<ValueLatticeElement>
1165getValueFromConditionImpl(Value *Val, Value *Cond, bool isTrueDest,
1166 bool isRevisit,
1167 SmallDenseMap<Value *, ValueLatticeElement> &Visited,
1168 SmallVectorImpl<Value *> &Worklist) {
1169 if (!isRevisit) {
1170 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Cond))
1171 return getValueFromICmpCondition(Val, ICI, isTrueDest);
1172
1173 if (auto *EVI = dyn_cast<ExtractValueInst>(Cond))
1174 if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand()))
1175 if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 1)
1176 return getValueFromOverflowCondition(Val, WO, isTrueDest);
1177 }
1178
1179 Value *L, *R;
1180 bool IsAnd;
1181 if (match(Cond, m_LogicalAnd(m_Value(L), m_Value(R))))
1182 IsAnd = true;
1183 else if (match(Cond, m_LogicalOr(m_Value(L), m_Value(R))))
1184 IsAnd = false;
1185 else
1186 return ValueLatticeElement::getOverdefined();
1187
1188 auto LV = Visited.find(L);
1189 auto RV = Visited.find(R);
1190
1191 // if (L && R) -> intersect L and R
1192 // if (!(L || R)) -> intersect L and R
1193 // if (L || R) -> union L and R
1194 // if (!(L && R)) -> union L and R
1195 if ((isTrueDest ^ IsAnd) && (LV != Visited.end())) {
1196 ValueLatticeElement V = LV->second;
1197 if (V.isOverdefined())
1198 return V;
1199 if (RV != Visited.end()) {
1200 V.mergeIn(RV->second);
1201 return V;
1202 }
1203 }
1204
1205 if (LV == Visited.end() || RV == Visited.end()) {
1206 assert(!isRevisit)(static_cast <bool> (!isRevisit) ? void (0) : __assert_fail
("!isRevisit", "llvm/lib/Analysis/LazyValueInfo.cpp", 1206, __extension__
__PRETTY_FUNCTION__))
;
1207 if (LV == Visited.end())
1208 Worklist.push_back(L);
1209 if (RV == Visited.end())
1210 Worklist.push_back(R);
1211 return None;
1212 }
1213
1214 return intersect(LV->second, RV->second);
1215}
1216
1217ValueLatticeElement getValueFromCondition(Value *Val, Value *Cond,
1218 bool isTrueDest) {
1219 assert(Cond && "precondition")(static_cast <bool> (Cond && "precondition") ? void
(0) : __assert_fail ("Cond && \"precondition\"", "llvm/lib/Analysis/LazyValueInfo.cpp"
, 1219, __extension__ __PRETTY_FUNCTION__))
;
1220 SmallDenseMap<Value*, ValueLatticeElement> Visited;
1221 SmallVector<Value *> Worklist;
1222
1223 Worklist.push_back(Cond);
1224 do {
1225 Value *CurrentCond = Worklist.back();
1226 // Insert an Overdefined placeholder into the set to prevent
1227 // infinite recursion if there exists IRs that use not
1228 // dominated by its def as in this example:
1229 // "%tmp3 = or i1 undef, %tmp4"
1230 // "%tmp4 = or i1 undef, %tmp3"
1231 auto Iter =
1232 Visited.try_emplace(CurrentCond, ValueLatticeElement::getOverdefined());
1233 bool isRevisit = !Iter.second;
1234 Optional<ValueLatticeElement> Result = getValueFromConditionImpl(
1235 Val, CurrentCond, isTrueDest, isRevisit, Visited, Worklist);
1236 if (Result) {
1237 Visited[CurrentCond] = *Result;
1238 Worklist.pop_back();
1239 }
1240 } while (!Worklist.empty());
1241
1242 auto Result = Visited.find(Cond);
1243 assert(Result != Visited.end())(static_cast <bool> (Result != Visited.end()) ? void (0
) : __assert_fail ("Result != Visited.end()", "llvm/lib/Analysis/LazyValueInfo.cpp"
, 1243, __extension__ __PRETTY_FUNCTION__))
;
1244 return Result->second;
1245}
1246
1247// Return true if Usr has Op as an operand, otherwise false.
1248static bool usesOperand(User *Usr, Value *Op) {
1249 return is_contained(Usr->operands(), Op);
1250}
1251
1252// Return true if the instruction type of Val is supported by
1253// constantFoldUser(). Currently CastInst, BinaryOperator and FreezeInst only.
1254// Call this before calling constantFoldUser() to find out if it's even worth
1255// attempting to call it.
1256static bool isOperationFoldable(User *Usr) {
1257 return isa<CastInst>(Usr) || isa<BinaryOperator>(Usr) || isa<FreezeInst>(Usr);
1258}
1259
1260// Check if Usr can be simplified to an integer constant when the value of one
1261// of its operands Op is an integer constant OpConstVal. If so, return it as an
1262// lattice value range with a single element or otherwise return an overdefined
1263// lattice value.
1264static ValueLatticeElement constantFoldUser(User *Usr, Value *Op,
1265 const APInt &OpConstVal,
1266 const DataLayout &DL) {
1267 assert(isOperationFoldable(Usr) && "Precondition")(static_cast <bool> (isOperationFoldable(Usr) &&
"Precondition") ? void (0) : __assert_fail ("isOperationFoldable(Usr) && \"Precondition\""
, "llvm/lib/Analysis/LazyValueInfo.cpp", 1267, __extension__ __PRETTY_FUNCTION__
))
;
1268 Constant* OpConst = Constant::getIntegerValue(Op->getType(), OpConstVal);
1269 // Check if Usr can be simplified to a constant.
1270 if (auto *CI = dyn_cast<CastInst>(Usr)) {
1271 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", 1271, __extension__ __PRETTY_FUNCTION__
))
;
1272 if (auto *C = dyn_cast_or_null<ConstantInt>(
1273 simplifyCastInst(CI->getOpcode(), OpConst,
1274 CI->getDestTy(), DL))) {
1275 return ValueLatticeElement::getRange(ConstantRange(C->getValue()));
1276 }
1277 } else if (auto *BO = dyn_cast<BinaryOperator>(Usr)) {
1278 bool Op0Match = BO->getOperand(0) == Op;
1279 bool Op1Match = BO->getOperand(1) == Op;
1280 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", 1281, __extension__ __PRETTY_FUNCTION__
))
1281 "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", 1281, __extension__ __PRETTY_FUNCTION__
))
;
1282 Value *LHS = Op0Match ? OpConst : BO->getOperand(0);
1283 Value *RHS = Op1Match ? OpConst : BO->getOperand(1);
1284 if (auto *C = dyn_cast_or_null<ConstantInt>(
1285 simplifyBinOp(BO->getOpcode(), LHS, RHS, DL))) {
1286 return ValueLatticeElement::getRange(ConstantRange(C->getValue()));
1287 }
1288 } else if (isa<FreezeInst>(Usr)) {
1289 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", 1289, __extension__ __PRETTY_FUNCTION__
))
;
1290 return ValueLatticeElement::getRange(ConstantRange(OpConstVal));
1291 }
1292 return ValueLatticeElement::getOverdefined();
1293}
1294
1295/// Compute the value of Val on the edge BBFrom -> BBTo. Returns false if
1296/// Val is not constrained on the edge. Result is unspecified if return value
1297/// is false.
1298static Optional<ValueLatticeElement> getEdgeValueLocal(Value *Val,
1299 BasicBlock *BBFrom,
1300 BasicBlock *BBTo) {
1301 // TODO: Handle more complex conditionals. If (v == 0 || v2 < 1) is false, we
1302 // know that v != 0.
1303 if (BranchInst *BI = dyn_cast<BranchInst>(BBFrom->getTerminator())) {
1304 // If this is a conditional branch and only one successor goes to BBTo, then
1305 // we may be able to infer something from the condition.
1306 if (BI->isConditional() &&
1307 BI->getSuccessor(0) != BI->getSuccessor(1)) {
1308 bool isTrueDest = BI->getSuccessor(0) == BBTo;
1309 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", 1310, __extension__ __PRETTY_FUNCTION__
))
1310 "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", 1310, __extension__ __PRETTY_FUNCTION__
))
;
1311 Value *Condition = BI->getCondition();
1312
1313 // If V is the condition of the branch itself, then we know exactly what
1314 // it is.
1315 if (Condition == Val)
1316 return ValueLatticeElement::get(ConstantInt::get(
1317 Type::getInt1Ty(Val->getContext()), isTrueDest));
1318
1319 // If the condition of the branch is an equality comparison, we may be
1320 // able to infer the value.
1321 ValueLatticeElement Result = getValueFromCondition(Val, Condition,
1322 isTrueDest);
1323 if (!Result.isOverdefined())
1324 return Result;
1325
1326 if (User *Usr = dyn_cast<User>(Val)) {
1327 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", 1327, __extension__ __PRETTY_FUNCTION__
))
;
1328 // Check with isOperationFoldable() first to avoid linearly iterating
1329 // over the operands unnecessarily which can be expensive for
1330 // instructions with many operands.
1331 if (isa<IntegerType>(Usr->getType()) && isOperationFoldable(Usr)) {
1332 const DataLayout &DL = BBTo->getModule()->getDataLayout();
1333 if (usesOperand(Usr, Condition)) {
1334 // If Val has Condition as an operand and Val can be folded into a
1335 // constant with either Condition == true or Condition == false,
1336 // propagate the constant.
1337 // eg.
1338 // ; %Val is true on the edge to %then.
1339 // %Val = and i1 %Condition, true.
1340 // br %Condition, label %then, label %else
1341 APInt ConditionVal(1, isTrueDest ? 1 : 0);
1342 Result = constantFoldUser(Usr, Condition, ConditionVal, DL);
1343 } else {
1344 // If one of Val's operand has an inferred value, we may be able to
1345 // infer the value of Val.
1346 // eg.
1347 // ; %Val is 94 on the edge to %then.
1348 // %Val = add i8 %Op, 1
1349 // %Condition = icmp eq i8 %Op, 93
1350 // br i1 %Condition, label %then, label %else
1351 for (unsigned i = 0; i < Usr->getNumOperands(); ++i) {
1352 Value *Op = Usr->getOperand(i);
1353 ValueLatticeElement OpLatticeVal =
1354 getValueFromCondition(Op, Condition, isTrueDest);
1355 if (Optional<APInt> OpConst = OpLatticeVal.asConstantInteger()) {
1356 Result = constantFoldUser(Usr, Op, *OpConst, DL);
1357 break;
1358 }
1359 }
1360 }
1361 }
1362 }
1363 if (!Result.isOverdefined())
1364 return Result;
1365 }
1366 }
1367
1368 // If the edge was formed by a switch on the value, then we may know exactly
1369 // what it is.
1370 if (SwitchInst *SI = dyn_cast<SwitchInst>(BBFrom->getTerminator())) {
1371 Value *Condition = SI->getCondition();
1372 if (!isa<IntegerType>(Val->getType()))
1373 return None;
1374 bool ValUsesConditionAndMayBeFoldable = false;
1375 if (Condition != Val) {
1376 // Check if Val has Condition as an operand.
1377 if (User *Usr = dyn_cast<User>(Val))
1378 ValUsesConditionAndMayBeFoldable = isOperationFoldable(Usr) &&
1379 usesOperand(Usr, Condition);
1380 if (!ValUsesConditionAndMayBeFoldable)
1381 return None;
1382 }
1383 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", 1384, __extension__ __PRETTY_FUNCTION__
))
1384 "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", 1384, __extension__ __PRETTY_FUNCTION__
))
;
1385
1386 bool DefaultCase = SI->getDefaultDest() == BBTo;
1387 unsigned BitWidth = Val->getType()->getIntegerBitWidth();
1388 ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/);
1389
1390 for (auto Case : SI->cases()) {
1391 APInt CaseValue = Case.getCaseValue()->getValue();
1392 ConstantRange EdgeVal(CaseValue);
1393 if (ValUsesConditionAndMayBeFoldable) {
1394 User *Usr = cast<User>(Val);
1395 const DataLayout &DL = BBTo->getModule()->getDataLayout();
1396 ValueLatticeElement EdgeLatticeVal =
1397 constantFoldUser(Usr, Condition, CaseValue, DL);
1398 if (EdgeLatticeVal.isOverdefined())
1399 return None;
1400 EdgeVal = EdgeLatticeVal.getConstantRange();
1401 }
1402 if (DefaultCase) {
1403 // It is possible that the default destination is the destination of
1404 // some cases. We cannot perform difference for those cases.
1405 // We know Condition != CaseValue in BBTo. In some cases we can use
1406 // this to infer Val == f(Condition) is != f(CaseValue). For now, we
1407 // only do this when f is identity (i.e. Val == Condition), but we
1408 // should be able to do this for any injective f.
1409 if (Case.getCaseSuccessor() != BBTo && Condition == Val)
1410 EdgesVals = EdgesVals.difference(EdgeVal);
1411 } else if (Case.getCaseSuccessor() == BBTo)
1412 EdgesVals = EdgesVals.unionWith(EdgeVal);
1413 }
1414 return ValueLatticeElement::getRange(std::move(EdgesVals));
1415 }
1416 return None;
1417}
1418
1419/// Compute the value of Val on the edge BBFrom -> BBTo or the value at
1420/// the basic block if the edge does not constrain Val.
1421Optional<ValueLatticeElement> LazyValueInfoImpl::getEdgeValue(
1422 Value *Val, BasicBlock *BBFrom, BasicBlock *BBTo, Instruction *CxtI) {
1423 // If already a constant, there is nothing to compute.
1424 if (Constant *VC = dyn_cast<Constant>(Val))
1425 return ValueLatticeElement::get(VC);
1426
1427 ValueLatticeElement LocalResult =
1428 getEdgeValueLocal(Val, BBFrom, BBTo)
1429 .value_or(ValueLatticeElement::getOverdefined());
1430 if (hasSingleValue(LocalResult))
1431 // Can't get any more precise here
1432 return LocalResult;
1433
1434 Optional<ValueLatticeElement> OptInBlock =
1435 getBlockValue(Val, BBFrom, BBFrom->getTerminator());
1436 if (!OptInBlock)
1437 return None;
1438 ValueLatticeElement &InBlock = *OptInBlock;
1439
1440 // We can use the context instruction (generically the ultimate instruction
1441 // the calling pass is trying to simplify) here, even though the result of
1442 // this function is generally cached when called from the solve* functions
1443 // (and that cached result might be used with queries using a different
1444 // context instruction), because when this function is called from the solve*
1445 // functions, the context instruction is not provided. When called from
1446 // LazyValueInfoImpl::getValueOnEdge, the context instruction is provided,
1447 // but then the result is not cached.
1448 intersectAssumeOrGuardBlockValueConstantRange(Val, InBlock, CxtI);
1449
1450 return intersect(LocalResult, InBlock);
1451}
1452
1453ValueLatticeElement LazyValueInfoImpl::getValueInBlock(Value *V, BasicBlock *BB,
1454 Instruction *CxtI) {
1455 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)
3
Assuming 'DebugFlag' is false
1456 << 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)
;
1457
1458 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", 1458, __extension__ __PRETTY_FUNCTION__
))
;
4
Loop condition is false. Exiting loop
5
Assuming the condition is true
6
'?' condition is true
1459 Optional<ValueLatticeElement> OptResult = getBlockValue(V, BB, CxtI);
1460 if (!OptResult) {
7
Taking false branch
1461 solve();
1462 OptResult = getBlockValue(V, BB, CxtI);
1463 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", 1463, __extension__ __PRETTY_FUNCTION__
))
;
1464 }
1465
1466 ValueLatticeElement Result = *OptResult;
8
Calling copy constructor for 'ValueLatticeElement'
12
Returning from copy constructor for 'ValueLatticeElement'
1467 LLVM_DEBUG(dbgs() << " Result = " << Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("lazy-value-info")) { dbgs() << " Result = " <<
Result << "\n"; } } while (false)
;
13
Assuming 'DebugFlag' is false
14
Loop condition is false. Exiting loop
1468 return Result;
15
Calling move constructor for 'ValueLatticeElement'
1469}
1470
1471ValueLatticeElement LazyValueInfoImpl::getValueAt(Value *V, Instruction *CxtI) {
1472 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)
1473 << "'\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("lazy-value-info")) { dbgs() << "LVI Getting value " <<
*V << " at '" << CxtI->getName() << "'\n"
; } } while (false)
;
1474
1475 if (auto *C = dyn_cast<Constant>(V))
1476 return ValueLatticeElement::get(C);
1477
1478 ValueLatticeElement Result = ValueLatticeElement::getOverdefined();
1479 if (auto *I = dyn_cast<Instruction>(V))
1480 Result = getFromRangeMetadata(I);
1481 intersectAssumeOrGuardBlockValueConstantRange(V, Result, CxtI);
1482
1483 LLVM_DEBUG(dbgs() << " Result = " << Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("lazy-value-info")) { dbgs() << " Result = " <<
Result << "\n"; } } while (false)
;
1484 return Result;
1485}
1486
1487ValueLatticeElement LazyValueInfoImpl::
1488getValueOnEdge(Value *V, BasicBlock *FromBB, BasicBlock *ToBB,
1489 Instruction *CxtI) {
1490 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)
1491 << 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)
1492 << "'\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)
;
1493
1494 Optional<ValueLatticeElement> Result = getEdgeValue(V, FromBB, ToBB, CxtI);
1495 if (!Result) {
1496 solve();
1497 Result = getEdgeValue(V, FromBB, ToBB, CxtI);
1498 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", 1498, __extension__ __PRETTY_FUNCTION__
))
;
1499 }
1500
1501 LLVM_DEBUG(dbgs() << " Result = " << *Result << "\n")do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
("lazy-value-info")) { dbgs() << " Result = " <<
*Result << "\n"; } } while (false)
;
1502 return *Result;
1503}
1504
1505void LazyValueInfoImpl::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
1506 BasicBlock *NewSucc) {
1507 TheCache.threadEdgeImpl(OldSucc, NewSucc);
1508}
1509
1510//===----------------------------------------------------------------------===//
1511// LazyValueInfo Impl
1512//===----------------------------------------------------------------------===//
1513
1514/// This lazily constructs the LazyValueInfoImpl.
1515static LazyValueInfoImpl &getImpl(void *&PImpl, AssumptionCache *AC,
1516 const Module *M) {
1517 if (!PImpl) {
1518 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", 1518, __extension__ __PRETTY_FUNCTION__
))
;
1519 const DataLayout &DL = M->getDataLayout();
1520 Function *GuardDecl = M->getFunction(
1521 Intrinsic::getName(Intrinsic::experimental_guard));
1522 PImpl = new LazyValueInfoImpl(AC, DL, GuardDecl);
1523 }
1524 return *static_cast<LazyValueInfoImpl*>(PImpl);
1525}
1526
1527bool LazyValueInfoWrapperPass::runOnFunction(Function &F) {
1528 Info.AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
1529 Info.TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
1530
1531 if (Info.PImpl)
1532 getImpl(Info.PImpl, Info.AC, F.getParent()).clear();
1533
1534 // Fully lazy.
1535 return false;
1536}
1537
1538void LazyValueInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
1539 AU.setPreservesAll();
1540 AU.addRequired<AssumptionCacheTracker>();
1541 AU.addRequired<TargetLibraryInfoWrapperPass>();
1542}
1543
1544LazyValueInfo &LazyValueInfoWrapperPass::getLVI() { return Info; }
1545
1546LazyValueInfo::~LazyValueInfo() { releaseMemory(); }
1547
1548void LazyValueInfo::releaseMemory() {
1549 // If the cache was allocated, free it.
1550 if (PImpl) {
1551 delete &getImpl(PImpl, AC, nullptr);
1552 PImpl = nullptr;
1553 }
1554}
1555
1556bool LazyValueInfo::invalidate(Function &F, const PreservedAnalyses &PA,
1557 FunctionAnalysisManager::Invalidator &Inv) {
1558 // We need to invalidate if we have either failed to preserve this analyses
1559 // result directly or if any of its dependencies have been invalidated.
1560 auto PAC = PA.getChecker<LazyValueAnalysis>();
1561 if (!(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>()))
1562 return true;
1563
1564 return false;
1565}
1566
1567void LazyValueInfoWrapperPass::releaseMemory() { Info.releaseMemory(); }
1568
1569LazyValueInfo LazyValueAnalysis::run(Function &F,
1570 FunctionAnalysisManager &FAM) {
1571 auto &AC = FAM.getResult<AssumptionAnalysis>(F);
1572 auto &TLI = FAM.getResult<TargetLibraryAnalysis>(F);
1573
1574 return LazyValueInfo(&AC, &F.getParent()->getDataLayout(), &TLI);
1575}
1576
1577/// Returns true if we can statically tell that this value will never be a
1578/// "useful" constant. In practice, this means we've got something like an
1579/// alloca or a malloc call for which a comparison against a constant can
1580/// only be guarding dead code. Note that we are potentially giving up some
1581/// precision in dead code (a constant result) in favour of avoiding a
1582/// expensive search for a easily answered common query.
1583static bool isKnownNonConstant(Value *V) {
1584 V = V->stripPointerCasts();
1585 // The return val of alloc cannot be a Constant.
1586 if (isa<AllocaInst>(V))
1587 return true;
1588 return false;
1589}
1590
1591Constant *LazyValueInfo::getConstant(Value *V, Instruction *CxtI) {
1592 // Bail out early if V is known not to be a Constant.
1593 if (isKnownNonConstant(V))
1594 return nullptr;
1595
1596 BasicBlock *BB = CxtI->getParent();
1597 ValueLatticeElement Result =
1598 getImpl(PImpl, AC, BB->getModule()).getValueInBlock(V, BB, CxtI);
1599
1600 if (Result.isConstant())
1601 return Result.getConstant();
1602 if (Result.isConstantRange()) {
1603 const ConstantRange &CR = Result.getConstantRange();
1604 if (const APInt *SingleVal = CR.getSingleElement())
1605 return ConstantInt::get(V->getContext(), *SingleVal);
1606 }
1607 return nullptr;
1608}
1609
1610ConstantRange LazyValueInfo::getConstantRange(Value *V, Instruction *CxtI,
1611 bool UndefAllowed) {
1612 assert(V->getType()->isIntegerTy())(static_cast <bool> (V->getType()->isIntegerTy())
? void (0) : __assert_fail ("V->getType()->isIntegerTy()"
, "llvm/lib/Analysis/LazyValueInfo.cpp", 1612, __extension__ __PRETTY_FUNCTION__
))
;
1
'?' condition is true
1613 unsigned Width = V->getType()->getIntegerBitWidth();
1614 BasicBlock *BB = CxtI->getParent();
1615 ValueLatticeElement Result =
1616 getImpl(PImpl, AC, BB->getModule()).getValueInBlock(V, BB, CxtI);
2
Calling 'LazyValueInfoImpl::getValueInBlock'
1617 if (Result.isUnknown())
1618 return ConstantRange::getEmpty(Width);
1619 if (Result.isConstantRange(UndefAllowed))
1620 return Result.getConstantRange(UndefAllowed);
1621 // We represent ConstantInt constants as constant ranges but other kinds
1622 // of integer constants, i.e. ConstantExpr will be tagged as constants
1623 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", 1624, __extension__ __PRETTY_FUNCTION__
))
1624 "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", 1624, __extension__ __PRETTY_FUNCTION__
))
;
1625 return ConstantRange::getFull(Width);
1626}
1627
1628/// Determine whether the specified value is known to be a
1629/// constant on the specified edge. Return null if not.
1630Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB,
1631 BasicBlock *ToBB,
1632 Instruction *CxtI) {
1633 Module *M = FromBB->getModule();
1634 ValueLatticeElement Result =
1635 getImpl(PImpl, AC, M).getValueOnEdge(V, FromBB, ToBB, CxtI);
1636
1637 if (Result.isConstant())
1638 return Result.getConstant();
1639 if (Result.isConstantRange()) {
1640 const ConstantRange &CR = Result.getConstantRange();
1641 if (const APInt *SingleVal = CR.getSingleElement())
1642 return ConstantInt::get(V->getContext(), *SingleVal);
1643 }
1644 return nullptr;
1645}
1646
1647ConstantRange LazyValueInfo::getConstantRangeOnEdge(Value *V,
1648 BasicBlock *FromBB,
1649 BasicBlock *ToBB,
1650 Instruction *CxtI) {
1651 unsigned Width = V->getType()->getIntegerBitWidth();
1652 Module *M = FromBB->getModule();
1653 ValueLatticeElement Result =
1654 getImpl(PImpl, AC, M).getValueOnEdge(V, FromBB, ToBB, CxtI);
1655
1656 if (Result.isUnknown())
1657 return ConstantRange::getEmpty(Width);
1658 if (Result.isConstantRange())
1659 return Result.getConstantRange();
1660 // We represent ConstantInt constants as constant ranges but other kinds
1661 // of integer constants, i.e. ConstantExpr will be tagged as constants
1662 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", 1663, __extension__ __PRETTY_FUNCTION__
))
1663 "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", 1663, __extension__ __PRETTY_FUNCTION__
))
;
1664 return ConstantRange::getFull(Width);
1665}
1666
1667static LazyValueInfo::Tristate
1668getPredicateResult(unsigned Pred, Constant *C, const ValueLatticeElement &Val,
1669 const DataLayout &DL, TargetLibraryInfo *TLI) {
1670 // If we know the value is a constant, evaluate the conditional.
1671 Constant *Res = nullptr;
1672 if (Val.isConstant()) {
1673 Res = ConstantFoldCompareInstOperands(Pred, Val.getConstant(), C, DL, TLI);
1674 if (ConstantInt *ResCI = dyn_cast<ConstantInt>(Res))
1675 return ResCI->isZero() ? LazyValueInfo::False : LazyValueInfo::True;
1676 return LazyValueInfo::Unknown;
1677 }
1678
1679 if (Val.isConstantRange()) {
1680 ConstantInt *CI = dyn_cast<ConstantInt>(C);
1681 if (!CI) return LazyValueInfo::Unknown;
1682
1683 const ConstantRange &CR = Val.getConstantRange();
1684 if (Pred == ICmpInst::ICMP_EQ) {
1685 if (!CR.contains(CI->getValue()))
1686 return LazyValueInfo::False;
1687
1688 if (CR.isSingleElement())
1689 return LazyValueInfo::True;
1690 } else if (Pred == ICmpInst::ICMP_NE) {
1691 if (!CR.contains(CI->getValue()))
1692 return LazyValueInfo::True;
1693
1694 if (CR.isSingleElement())
1695 return LazyValueInfo::False;
1696 } else {
1697 // Handle more complex predicates.
1698 ConstantRange TrueValues = ConstantRange::makeExactICmpRegion(
1699 (ICmpInst::Predicate)Pred, CI->getValue());
1700 if (TrueValues.contains(CR))
1701 return LazyValueInfo::True;
1702 if (TrueValues.inverse().contains(CR))
1703 return LazyValueInfo::False;
1704 }
1705 return LazyValueInfo::Unknown;
1706 }
1707
1708 if (Val.isNotConstant()) {
1709 // If this is an equality comparison, we can try to fold it knowing that
1710 // "V != C1".
1711 if (Pred == ICmpInst::ICMP_EQ) {
1712 // !C1 == C -> false iff C1 == C.
1713 Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
1714 Val.getNotConstant(), C, DL,
1715 TLI);
1716 if (Res->isNullValue())
1717 return LazyValueInfo::False;
1718 } else if (Pred == ICmpInst::ICMP_NE) {
1719 // !C1 != C -> true iff C1 == C.
1720 Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE,
1721 Val.getNotConstant(), C, DL,
1722 TLI);
1723 if (Res->isNullValue())
1724 return LazyValueInfo::True;
1725 }
1726 return LazyValueInfo::Unknown;
1727 }
1728
1729 return LazyValueInfo::Unknown;
1730}
1731
1732/// Determine whether the specified value comparison with a constant is known to
1733/// be true or false on the specified CFG edge. Pred is a CmpInst predicate.
1734LazyValueInfo::Tristate
1735LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C,
1736 BasicBlock *FromBB, BasicBlock *ToBB,
1737 Instruction *CxtI) {
1738 Module *M = FromBB->getModule();
1739 ValueLatticeElement Result =
1740 getImpl(PImpl, AC, M).getValueOnEdge(V, FromBB, ToBB, CxtI);
1741
1742 return getPredicateResult(Pred, C, Result, M->getDataLayout(), TLI);
1743}
1744
1745LazyValueInfo::Tristate
1746LazyValueInfo::getPredicateAt(unsigned Pred, Value *V, Constant *C,
1747 Instruction *CxtI, bool UseBlockValue) {
1748 // Is or is not NonNull are common predicates being queried. If
1749 // isKnownNonZero can tell us the result of the predicate, we can
1750 // return it quickly. But this is only a fastpath, and falling
1751 // through would still be correct.
1752 Module *M = CxtI->getModule();
1753 const DataLayout &DL = M->getDataLayout();
1754 if (V->getType()->isPointerTy() && C->isNullValue() &&
1755 isKnownNonZero(V->stripPointerCastsSameRepresentation(), DL)) {
1756 if (Pred == ICmpInst::ICMP_EQ)
1757 return LazyValueInfo::False;
1758 else if (Pred == ICmpInst::ICMP_NE)
1759 return LazyValueInfo::True;
1760 }
1761
1762 ValueLatticeElement Result = UseBlockValue
1763 ? getImpl(PImpl, AC, M).getValueInBlock(V, CxtI->getParent(), CxtI)
1764 : getImpl(PImpl, AC, M).getValueAt(V, CxtI);
1765 Tristate Ret = getPredicateResult(Pred, C, Result, DL, TLI);
1766 if (Ret != Unknown)
1767 return Ret;
1768
1769 // Note: The following bit of code is somewhat distinct from the rest of LVI;
1770 // LVI as a whole tries to compute a lattice value which is conservatively
1771 // correct at a given location. In this case, we have a predicate which we
1772 // weren't able to prove about the merged result, and we're pushing that
1773 // predicate back along each incoming edge to see if we can prove it
1774 // separately for each input. As a motivating example, consider:
1775 // bb1:
1776 // %v1 = ... ; constantrange<1, 5>
1777 // br label %merge
1778 // bb2:
1779 // %v2 = ... ; constantrange<10, 20>
1780 // br label %merge
1781 // merge:
1782 // %phi = phi [%v1, %v2] ; constantrange<1,20>
1783 // %pred = icmp eq i32 %phi, 8
1784 // We can't tell from the lattice value for '%phi' that '%pred' is false
1785 // along each path, but by checking the predicate over each input separately,
1786 // we can.
1787 // We limit the search to one step backwards from the current BB and value.
1788 // We could consider extending this to search further backwards through the
1789 // CFG and/or value graph, but there are non-obvious compile time vs quality
1790 // tradeoffs.
1791 BasicBlock *BB = CxtI->getParent();
1792
1793 // Function entry or an unreachable block. Bail to avoid confusing
1794 // analysis below.
1795 pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
1796 if (PI == PE)
1797 return Unknown;
1798
1799 // If V is a PHI node in the same block as the context, we need to ask
1800 // questions about the predicate as applied to the incoming value along
1801 // each edge. This is useful for eliminating cases where the predicate is
1802 // known along all incoming edges.
1803 if (auto *PHI = dyn_cast<PHINode>(V))
1804 if (PHI->getParent() == BB) {
1805 Tristate Baseline = Unknown;
1806 for (unsigned i = 0, e = PHI->getNumIncomingValues(); i < e; i++) {
1807 Value *Incoming = PHI->getIncomingValue(i);
1808 BasicBlock *PredBB = PHI->getIncomingBlock(i);
1809 // Note that PredBB may be BB itself.
1810 Tristate Result =
1811 getPredicateOnEdge(Pred, Incoming, C, PredBB, BB, CxtI);
1812
1813 // Keep going as long as we've seen a consistent known result for
1814 // all inputs.
1815 Baseline = (i == 0) ? Result /* First iteration */
1816 : (Baseline == Result ? Baseline
1817 : Unknown); /* All others */
1818 if (Baseline == Unknown)
1819 break;
1820 }
1821 if (Baseline != Unknown)
1822 return Baseline;
1823 }
1824
1825 // For a comparison where the V is outside this block, it's possible
1826 // that we've branched on it before. Look to see if the value is known
1827 // on all incoming edges.
1828 if (!isa<Instruction>(V) || cast<Instruction>(V)->getParent() != BB) {
1829 // For predecessor edge, determine if the comparison is true or false
1830 // on that edge. If they're all true or all false, we can conclude
1831 // the value of the comparison in this block.
1832 Tristate Baseline = getPredicateOnEdge(Pred, V, C, *PI, BB, CxtI);
1833 if (Baseline != Unknown) {
1834 // Check that all remaining incoming values match the first one.
1835 while (++PI != PE) {
1836 Tristate Ret = getPredicateOnEdge(Pred, V, C, *PI, BB, CxtI);
1837 if (Ret != Baseline)
1838 break;
1839 }
1840 // If we terminated early, then one of the values didn't match.
1841 if (PI == PE) {
1842 return Baseline;
1843 }
1844 }
1845 }
1846
1847 return Unknown;
1848}
1849
1850LazyValueInfo::Tristate LazyValueInfo::getPredicateAt(unsigned P, Value *LHS,
1851 Value *RHS,
1852 Instruction *CxtI,
1853 bool UseBlockValue) {
1854 CmpInst::Predicate Pred = (CmpInst::Predicate)P;
1855
1856 if (auto *C = dyn_cast<Constant>(RHS))
1857 return getPredicateAt(P, LHS, C, CxtI, UseBlockValue);
1858 if (auto *C = dyn_cast<Constant>(LHS))
1859 return getPredicateAt(CmpInst::getSwappedPredicate(Pred), RHS, C, CxtI,
1860 UseBlockValue);
1861
1862 // Got two non-Constant values. While we could handle them somewhat,
1863 // by getting their constant ranges, and applying ConstantRange::icmp(),
1864 // so far it did not appear to be profitable.
1865 return LazyValueInfo::Unknown;
1866}
1867
1868void LazyValueInfo::threadEdge(BasicBlock *PredBB, BasicBlock *OldSucc,
1869 BasicBlock *NewSucc) {
1870 if (PImpl) {
1871 getImpl(PImpl, AC, PredBB->getModule())
1872 .threadEdge(PredBB, OldSucc, NewSucc);
1873 }
1874}
1875
1876void LazyValueInfo::eraseBlock(BasicBlock *BB) {
1877 if (PImpl) {
1878 getImpl(PImpl, AC, BB->getModule()).eraseBlock(BB);
1879 }
1880}
1881
1882void LazyValueInfo::clear(const Module *M) {
1883 if (PImpl) {
1884 getImpl(PImpl, AC, M).clear();
1885 }
1886}
1887
1888void LazyValueInfo::printLVI(Function &F, DominatorTree &DTree, raw_ostream &OS) {
1889 if (PImpl) {
1890 getImpl(PImpl, AC, F.getParent()).printLVI(F, DTree, OS);
1891 }
1892}
1893
1894// Print the LVI for the function arguments at the start of each basic block.
1895void LazyValueInfoAnnotatedWriter::emitBasicBlockStartAnnot(
1896 const BasicBlock *BB, formatted_raw_ostream &OS) {
1897 // Find if there are latticevalues defined for arguments of the function.
1898 auto *F = BB->getParent();
1899 for (const auto &Arg : F->args()) {
1900 ValueLatticeElement Result = LVIImpl->getValueInBlock(
1901 const_cast<Argument *>(&Arg), const_cast<BasicBlock *>(BB));
1902 if (Result.isUnknown())
1903 continue;
1904 OS << "; LatticeVal for: '" << Arg << "' is: " << Result << "\n";
1905 }
1906}
1907
1908// This function prints the LVI analysis for the instruction I at the beginning
1909// of various basic blocks. It relies on calculated values that are stored in
1910// the LazyValueInfoCache, and in the absence of cached values, recalculate the
1911// LazyValueInfo for `I`, and print that info.
1912void LazyValueInfoAnnotatedWriter::emitInstructionAnnot(
1913 const Instruction *I, formatted_raw_ostream &OS) {
1914
1915 auto *ParentBB = I->getParent();
1916 SmallPtrSet<const BasicBlock*, 16> BlocksContainingLVI;
1917 // We can generate (solve) LVI values only for blocks that are dominated by
1918 // the I's parent. However, to avoid generating LVI for all dominating blocks,
1919 // that contain redundant/uninteresting information, we print LVI for
1920 // blocks that may use this LVI information (such as immediate successor
1921 // blocks, and blocks that contain uses of `I`).
1922 auto printResult = [&](const BasicBlock *BB) {
1923 if (!BlocksContainingLVI.insert(BB).second)
1924 return;
1925 ValueLatticeElement Result = LVIImpl->getValueInBlock(
1926 const_cast<Instruction *>(I), const_cast<BasicBlock *>(BB));
1927 OS << "; LatticeVal for: '" << *I << "' in BB: '";
1928 BB->printAsOperand(OS, false);
1929 OS << "' is: " << Result << "\n";
1930 };
1931
1932 printResult(ParentBB);
1933 // Print the LVI analysis results for the immediate successor blocks, that
1934 // are dominated by `ParentBB`.
1935 for (const auto *BBSucc : successors(ParentBB))
1936 if (DT.dominates(ParentBB, BBSucc))
1937 printResult(BBSucc);
1938
1939 // Print LVI in blocks where `I` is used.
1940 for (const auto *U : I->users())
1941 if (auto *UseI = dyn_cast<Instruction>(U))
1942 if (!isa<PHINode>(UseI) || DT.dominates(ParentBB, UseI->getParent()))
1943 printResult(UseI->getParent());
1944
1945}
1946
1947namespace {
1948// Printer class for LazyValueInfo results.
1949class LazyValueInfoPrinter : public FunctionPass {
1950public:
1951 static char ID; // Pass identification, replacement for typeid
1952 LazyValueInfoPrinter() : FunctionPass(ID) {
1953 initializeLazyValueInfoPrinterPass(*PassRegistry::getPassRegistry());
1954 }
1955
1956 void getAnalysisUsage(AnalysisUsage &AU) const override {
1957 AU.setPreservesAll();
1958 AU.addRequired<LazyValueInfoWrapperPass>();
1959 AU.addRequired<DominatorTreeWrapperPass>();
1960 }
1961
1962 // Get the mandatory dominator tree analysis and pass this in to the
1963 // LVIPrinter. We cannot rely on the LVI's DT, since it's optional.
1964 bool runOnFunction(Function &F) override {
1965 dbgs() << "LVI for function '" << F.getName() << "':\n";
1966 auto &LVI = getAnalysis<LazyValueInfoWrapperPass>().getLVI();
1967 auto &DTree = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1968 LVI.printLVI(F, DTree, dbgs());
1969 return false;
1970 }
1971};
1972}
1973
1974char LazyValueInfoPrinter::ID = 0;
1975INITIALIZE_PASS_BEGIN(LazyValueInfoPrinter, "print-lazy-value-info",static void *initializeLazyValueInfoPrinterPassOnce(PassRegistry
&Registry) {
1976 "Lazy Value Info Printer Pass", false, false)static void *initializeLazyValueInfoPrinterPassOnce(PassRegistry
&Registry) {
1977INITIALIZE_PASS_DEPENDENCY(LazyValueInfoWrapperPass)initializeLazyValueInfoWrapperPassPass(Registry);
1978INITIALIZE_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))
; }
1979 "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))
; }

/build/llvm-toolchain-snapshot-16~++20220904122748+c444af1c20b3/llvm/include/llvm/Analysis/ValueLattice.h

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
20namespace llvm {
21
22class 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///
29class 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
109public:
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) {
9
Control jumps to 'case undef:' at line 166
10
Execution continues on line 154
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 }
11
Returning without writing to 'this->.ConstVal'
170
171 ValueLatticeElement(ValueLatticeElement &&Other)
172 : Tag(Other.Tag), NumRangeExtensions(0) {
173 switch (Other.Tag) {
16
Control jumps to 'case notconstant:' at line 180
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;
17
Assigned value is garbage or undefined
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
491static_assert(sizeof(ValueLatticeElement) <= 40,
492 "size of ValueLatticeElement changed unexpectedly");
493
494raw_ostream &operator<<(raw_ostream &OS, const ValueLatticeElement &Val);
495} // end namespace llvm
496#endif