1 //===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
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 #include "llvm/Analysis/AliasAnalysisEvaluator.h"
10 #include "llvm/ADT/SetVector.h"
11 #include "llvm/Analysis/AliasAnalysis.h"
12 #include "llvm/IR/Constants.h"
13 #include "llvm/IR/DataLayout.h"
14 #include "llvm/IR/DerivedTypes.h"
15 #include "llvm/IR/Function.h"
16 #include "llvm/IR/InstIterator.h"
17 #include "llvm/IR/Instructions.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/InitializePasses.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/raw_ostream.h"
24 using namespace llvm;
25
26 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
27
28 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
29 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
30 static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
31 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
32
33 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
34 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
35 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
36 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
37 static cl::opt<bool> PrintMust("print-must", cl::ReallyHidden);
38 static cl::opt<bool> PrintMustRef("print-mustref", cl::ReallyHidden);
39 static cl::opt<bool> PrintMustMod("print-mustmod", cl::ReallyHidden);
40 static cl::opt<bool> PrintMustModRef("print-mustmodref", cl::ReallyHidden);
41
42 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
43
PrintResults(AliasResult AR,bool P,const Value * V1,const Value * V2,const Module * M)44 static void PrintResults(AliasResult AR, bool P, const Value *V1,
45 const Value *V2, const Module *M) {
46 if (PrintAll || P) {
47 std::string o1, o2;
48 {
49 raw_string_ostream os1(o1), os2(o2);
50 V1->printAsOperand(os1, true, M);
51 V2->printAsOperand(os2, true, M);
52 }
53
54 if (o2 < o1)
55 std::swap(o1, o2);
56 errs() << " " << AR << ":\t" << o1 << ", " << o2 << "\n";
57 }
58 }
59
PrintModRefResults(const char * Msg,bool P,Instruction * I,Value * Ptr,Module * M)60 static inline void PrintModRefResults(const char *Msg, bool P, Instruction *I,
61 Value *Ptr, Module *M) {
62 if (PrintAll || P) {
63 errs() << " " << Msg << ": Ptr: ";
64 Ptr->printAsOperand(errs(), true, M);
65 errs() << "\t<->" << *I << '\n';
66 }
67 }
68
PrintModRefResults(const char * Msg,bool P,CallBase * CallA,CallBase * CallB,Module * M)69 static inline void PrintModRefResults(const char *Msg, bool P, CallBase *CallA,
70 CallBase *CallB, Module *M) {
71 if (PrintAll || P) {
72 errs() << " " << Msg << ": " << *CallA << " <-> " << *CallB << '\n';
73 }
74 }
75
PrintLoadStoreResults(AliasResult AR,bool P,const Value * V1,const Value * V2,const Module * M)76 static inline void PrintLoadStoreResults(AliasResult AR, bool P,
77 const Value *V1, const Value *V2,
78 const Module *M) {
79 if (PrintAll || P) {
80 errs() << " " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
81 }
82 }
83
isInterestingPointer(Value * V)84 static inline bool isInterestingPointer(Value *V) {
85 return V->getType()->isPointerTy()
86 && !isa<ConstantPointerNull>(V);
87 }
88
run(Function & F,FunctionAnalysisManager & AM)89 PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
90 runInternal(F, AM.getResult<AAManager>(F));
91 return PreservedAnalyses::all();
92 }
93
runInternal(Function & F,AAResults & AA)94 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
95 const DataLayout &DL = F.getParent()->getDataLayout();
96
97 ++FunctionCount;
98
99 SetVector<Value *> Pointers;
100 SmallSetVector<CallBase *, 16> Calls;
101 SetVector<Value *> Loads;
102 SetVector<Value *> Stores;
103
104 for (auto &I : F.args())
105 if (I.getType()->isPointerTy()) // Add all pointer arguments.
106 Pointers.insert(&I);
107
108 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
109 if (I->getType()->isPointerTy()) // Add all pointer instructions.
110 Pointers.insert(&*I);
111 if (EvalAAMD && isa<LoadInst>(&*I))
112 Loads.insert(&*I);
113 if (EvalAAMD && isa<StoreInst>(&*I))
114 Stores.insert(&*I);
115 Instruction &Inst = *I;
116 if (auto *Call = dyn_cast<CallBase>(&Inst)) {
117 Value *Callee = Call->getCalledValue();
118 // Skip actual functions for direct function calls.
119 if (!isa<Function>(Callee) && isInterestingPointer(Callee))
120 Pointers.insert(Callee);
121 // Consider formals.
122 for (Use &DataOp : Call->data_ops())
123 if (isInterestingPointer(DataOp))
124 Pointers.insert(DataOp);
125 Calls.insert(Call);
126 } else {
127 // Consider all operands.
128 for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
129 OI != OE; ++OI)
130 if (isInterestingPointer(*OI))
131 Pointers.insert(*OI);
132 }
133 }
134
135 if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
136 PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
137 errs() << "Function: " << F.getName() << ": " << Pointers.size()
138 << " pointers, " << Calls.size() << " call sites\n";
139
140 // iterate over the worklist, and run the full (n^2)/2 disambiguations
141 for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
142 I1 != E; ++I1) {
143 auto I1Size = LocationSize::unknown();
144 Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
145 if (I1ElTy->isSized())
146 I1Size = LocationSize::precise(DL.getTypeStoreSize(I1ElTy));
147
148 for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
149 auto I2Size = LocationSize::unknown();
150 Type *I2ElTy = cast<PointerType>((*I2)->getType())->getElementType();
151 if (I2ElTy->isSized())
152 I2Size = LocationSize::precise(DL.getTypeStoreSize(I2ElTy));
153
154 AliasResult AR = AA.alias(*I1, I1Size, *I2, I2Size);
155 switch (AR) {
156 case NoAlias:
157 PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
158 ++NoAliasCount;
159 break;
160 case MayAlias:
161 PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
162 ++MayAliasCount;
163 break;
164 case PartialAlias:
165 PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
166 ++PartialAliasCount;
167 break;
168 case MustAlias:
169 PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
170 ++MustAliasCount;
171 break;
172 }
173 }
174 }
175
176 if (EvalAAMD) {
177 // iterate over all pairs of load, store
178 for (Value *Load : Loads) {
179 for (Value *Store : Stores) {
180 AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
181 MemoryLocation::get(cast<StoreInst>(Store)));
182 switch (AR) {
183 case NoAlias:
184 PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
185 ++NoAliasCount;
186 break;
187 case MayAlias:
188 PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
189 ++MayAliasCount;
190 break;
191 case PartialAlias:
192 PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
193 ++PartialAliasCount;
194 break;
195 case MustAlias:
196 PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
197 ++MustAliasCount;
198 break;
199 }
200 }
201 }
202
203 // iterate over all pairs of store, store
204 for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
205 I1 != E; ++I1) {
206 for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
207 AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
208 MemoryLocation::get(cast<StoreInst>(*I2)));
209 switch (AR) {
210 case NoAlias:
211 PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
212 ++NoAliasCount;
213 break;
214 case MayAlias:
215 PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
216 ++MayAliasCount;
217 break;
218 case PartialAlias:
219 PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
220 ++PartialAliasCount;
221 break;
222 case MustAlias:
223 PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
224 ++MustAliasCount;
225 break;
226 }
227 }
228 }
229 }
230
231 // Mod/ref alias analysis: compare all pairs of calls and values
232 for (CallBase *Call : Calls) {
233 for (auto Pointer : Pointers) {
234 auto Size = LocationSize::unknown();
235 Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
236 if (ElTy->isSized())
237 Size = LocationSize::precise(DL.getTypeStoreSize(ElTy));
238
239 switch (AA.getModRefInfo(Call, Pointer, Size)) {
240 case ModRefInfo::NoModRef:
241 PrintModRefResults("NoModRef", PrintNoModRef, Call, Pointer,
242 F.getParent());
243 ++NoModRefCount;
244 break;
245 case ModRefInfo::Mod:
246 PrintModRefResults("Just Mod", PrintMod, Call, Pointer, F.getParent());
247 ++ModCount;
248 break;
249 case ModRefInfo::Ref:
250 PrintModRefResults("Just Ref", PrintRef, Call, Pointer, F.getParent());
251 ++RefCount;
252 break;
253 case ModRefInfo::ModRef:
254 PrintModRefResults("Both ModRef", PrintModRef, Call, Pointer,
255 F.getParent());
256 ++ModRefCount;
257 break;
258 case ModRefInfo::Must:
259 PrintModRefResults("Must", PrintMust, Call, Pointer, F.getParent());
260 ++MustCount;
261 break;
262 case ModRefInfo::MustMod:
263 PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, Call, Pointer,
264 F.getParent());
265 ++MustModCount;
266 break;
267 case ModRefInfo::MustRef:
268 PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, Call, Pointer,
269 F.getParent());
270 ++MustRefCount;
271 break;
272 case ModRefInfo::MustModRef:
273 PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, Call,
274 Pointer, F.getParent());
275 ++MustModRefCount;
276 break;
277 }
278 }
279 }
280
281 // Mod/ref alias analysis: compare all pairs of calls
282 for (CallBase *CallA : Calls) {
283 for (CallBase *CallB : Calls) {
284 if (CallA == CallB)
285 continue;
286 switch (AA.getModRefInfo(CallA, CallB)) {
287 case ModRefInfo::NoModRef:
288 PrintModRefResults("NoModRef", PrintNoModRef, CallA, CallB,
289 F.getParent());
290 ++NoModRefCount;
291 break;
292 case ModRefInfo::Mod:
293 PrintModRefResults("Just Mod", PrintMod, CallA, CallB, F.getParent());
294 ++ModCount;
295 break;
296 case ModRefInfo::Ref:
297 PrintModRefResults("Just Ref", PrintRef, CallA, CallB, F.getParent());
298 ++RefCount;
299 break;
300 case ModRefInfo::ModRef:
301 PrintModRefResults("Both ModRef", PrintModRef, CallA, CallB,
302 F.getParent());
303 ++ModRefCount;
304 break;
305 case ModRefInfo::Must:
306 PrintModRefResults("Must", PrintMust, CallA, CallB, F.getParent());
307 ++MustCount;
308 break;
309 case ModRefInfo::MustMod:
310 PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, CallA, CallB,
311 F.getParent());
312 ++MustModCount;
313 break;
314 case ModRefInfo::MustRef:
315 PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, CallA, CallB,
316 F.getParent());
317 ++MustRefCount;
318 break;
319 case ModRefInfo::MustModRef:
320 PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, CallA,
321 CallB, F.getParent());
322 ++MustModRefCount;
323 break;
324 }
325 }
326 }
327 }
328
PrintPercent(int64_t Num,int64_t Sum)329 static void PrintPercent(int64_t Num, int64_t Sum) {
330 errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
331 << "%)\n";
332 }
333
~AAEvaluator()334 AAEvaluator::~AAEvaluator() {
335 if (FunctionCount == 0)
336 return;
337
338 int64_t AliasSum =
339 NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
340 errs() << "===== Alias Analysis Evaluator Report =====\n";
341 if (AliasSum == 0) {
342 errs() << " Alias Analysis Evaluator Summary: No pointers!\n";
343 } else {
344 errs() << " " << AliasSum << " Total Alias Queries Performed\n";
345 errs() << " " << NoAliasCount << " no alias responses ";
346 PrintPercent(NoAliasCount, AliasSum);
347 errs() << " " << MayAliasCount << " may alias responses ";
348 PrintPercent(MayAliasCount, AliasSum);
349 errs() << " " << PartialAliasCount << " partial alias responses ";
350 PrintPercent(PartialAliasCount, AliasSum);
351 errs() << " " << MustAliasCount << " must alias responses ";
352 PrintPercent(MustAliasCount, AliasSum);
353 errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
354 << NoAliasCount * 100 / AliasSum << "%/"
355 << MayAliasCount * 100 / AliasSum << "%/"
356 << PartialAliasCount * 100 / AliasSum << "%/"
357 << MustAliasCount * 100 / AliasSum << "%\n";
358 }
359
360 // Display the summary for mod/ref analysis
361 int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
362 MustCount + MustRefCount + MustModCount + MustModRefCount;
363 if (ModRefSum == 0) {
364 errs() << " Alias Analysis Mod/Ref Evaluator Summary: no "
365 "mod/ref!\n";
366 } else {
367 errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
368 errs() << " " << NoModRefCount << " no mod/ref responses ";
369 PrintPercent(NoModRefCount, ModRefSum);
370 errs() << " " << ModCount << " mod responses ";
371 PrintPercent(ModCount, ModRefSum);
372 errs() << " " << RefCount << " ref responses ";
373 PrintPercent(RefCount, ModRefSum);
374 errs() << " " << ModRefCount << " mod & ref responses ";
375 PrintPercent(ModRefCount, ModRefSum);
376 errs() << " " << MustCount << " must responses ";
377 PrintPercent(MustCount, ModRefSum);
378 errs() << " " << MustModCount << " must mod responses ";
379 PrintPercent(MustModCount, ModRefSum);
380 errs() << " " << MustRefCount << " must ref responses ";
381 PrintPercent(MustRefCount, ModRefSum);
382 errs() << " " << MustModRefCount << " must mod & ref responses ";
383 PrintPercent(MustModRefCount, ModRefSum);
384 errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
385 << NoModRefCount * 100 / ModRefSum << "%/"
386 << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
387 << "%/" << ModRefCount * 100 / ModRefSum << "%/"
388 << MustCount * 100 / ModRefSum << "%/"
389 << MustRefCount * 100 / ModRefSum << "%/"
390 << MustModCount * 100 / ModRefSum << "%/"
391 << MustModRefCount * 100 / ModRefSum << "%\n";
392 }
393 }
394
395 namespace llvm {
396 class AAEvalLegacyPass : public FunctionPass {
397 std::unique_ptr<AAEvaluator> P;
398
399 public:
400 static char ID; // Pass identification, replacement for typeid
AAEvalLegacyPass()401 AAEvalLegacyPass() : FunctionPass(ID) {
402 initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
403 }
404
getAnalysisUsage(AnalysisUsage & AU) const405 void getAnalysisUsage(AnalysisUsage &AU) const override {
406 AU.addRequired<AAResultsWrapperPass>();
407 AU.setPreservesAll();
408 }
409
doInitialization(Module & M)410 bool doInitialization(Module &M) override {
411 P.reset(new AAEvaluator());
412 return false;
413 }
414
runOnFunction(Function & F)415 bool runOnFunction(Function &F) override {
416 P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
417 return false;
418 }
doFinalization(Module & M)419 bool doFinalization(Module &M) override {
420 P.reset();
421 return false;
422 }
423 };
424 }
425
426 char AAEvalLegacyPass::ID = 0;
427 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
428 "Exhaustive Alias Analysis Precision Evaluator", false,
429 true)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)430 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
431 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
432 "Exhaustive Alias Analysis Precision Evaluator", false,
433 true)
434
435 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
436