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/DataLayout.h"
13 #include "llvm/IR/Function.h"
14 #include "llvm/IR/InstIterator.h"
15 #include "llvm/IR/Instructions.h"
16 #include "llvm/IR/Module.h"
17 #include "llvm/InitializePasses.h"
18 #include "llvm/Pass.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Support/raw_ostream.h"
21 using namespace llvm;
22 
23 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
24 
25 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
26 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
27 static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
28 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
29 
30 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
31 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
32 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
33 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
34 static cl::opt<bool> PrintMust("print-must", cl::ReallyHidden);
35 static cl::opt<bool> PrintMustRef("print-mustref", cl::ReallyHidden);
36 static cl::opt<bool> PrintMustMod("print-mustmod", cl::ReallyHidden);
37 static cl::opt<bool> PrintMustModRef("print-mustmodref", cl::ReallyHidden);
38 
39 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
40 
PrintResults(AliasResult AR,bool P,std::pair<const Value *,Type * > Loc1,std::pair<const Value *,Type * > Loc2,const Module * M)41 static void PrintResults(AliasResult AR, bool P,
42                          std::pair<const Value *, Type *> Loc1,
43                          std::pair<const Value *, Type *> Loc2,
44                          const Module *M) {
45   if (PrintAll || P) {
46     Type *Ty1 = Loc1.second, *Ty2 = Loc2.second;
47     unsigned AS1 = Loc1.first->getType()->getPointerAddressSpace();
48     unsigned AS2 = Loc2.first->getType()->getPointerAddressSpace();
49     std::string o1, o2;
50     {
51       raw_string_ostream os1(o1), os2(o2);
52       Loc1.first->printAsOperand(os1, false, M);
53       Loc2.first->printAsOperand(os2, false, M);
54     }
55 
56     if (o2 < o1) {
57       std::swap(o1, o2);
58       std::swap(Ty1, Ty2);
59       std::swap(AS1, AS2);
60       // Change offset sign for the local AR, for printing only.
61       AR.swap();
62     }
63     errs() << "  " << AR << ":\t";
64     Ty1->print(errs(), false, /* NoDetails */ true);
65     if (AS1 != 0)
66       errs() << " addrspace(" << AS1 << ")";
67     errs() << "* " << o1 << ", ";
68     Ty2->print(errs(), false, /* NoDetails */ true);
69     if (AS2 != 0)
70       errs() << " addrspace(" << AS2 << ")";
71     errs() << "* " << o2 << "\n";
72   }
73 }
74 
PrintModRefResults(const char * Msg,bool P,Instruction * I,std::pair<const Value *,Type * > Loc,Module * M)75 static inline void PrintModRefResults(
76     const char *Msg, bool P, Instruction *I,
77     std::pair<const Value *, Type *> Loc, Module *M) {
78   if (PrintAll || P) {
79     errs() << "  " << Msg << ":  Ptr: ";
80     Loc.second->print(errs(), false, /* NoDetails */ true);
81     errs() << "* ";
82     Loc.first->printAsOperand(errs(), false, M);
83     errs() << "\t<->" << *I << '\n';
84   }
85 }
86 
PrintModRefResults(const char * Msg,bool P,CallBase * CallA,CallBase * CallB,Module * M)87 static inline void PrintModRefResults(const char *Msg, bool P, CallBase *CallA,
88                                       CallBase *CallB, Module *M) {
89   if (PrintAll || P) {
90     errs() << "  " << Msg << ": " << *CallA << " <-> " << *CallB << '\n';
91   }
92 }
93 
PrintLoadStoreResults(AliasResult AR,bool P,const Value * V1,const Value * V2,const Module * M)94 static inline void PrintLoadStoreResults(AliasResult AR, bool P,
95                                          const Value *V1, const Value *V2,
96                                          const Module *M) {
97   if (PrintAll || P) {
98     errs() << "  " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
99   }
100 }
101 
run(Function & F,FunctionAnalysisManager & AM)102 PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
103   runInternal(F, AM.getResult<AAManager>(F));
104   return PreservedAnalyses::all();
105 }
106 
runInternal(Function & F,AAResults & AA)107 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
108   const DataLayout &DL = F.getParent()->getDataLayout();
109 
110   ++FunctionCount;
111 
112   SetVector<std::pair<const Value *, Type *>> Pointers;
113   SmallSetVector<CallBase *, 16> Calls;
114   SetVector<Value *> Loads;
115   SetVector<Value *> Stores;
116 
117   for (Instruction &Inst : instructions(F)) {
118     if (auto *LI = dyn_cast<LoadInst>(&Inst)) {
119       Pointers.insert({LI->getPointerOperand(), LI->getType()});
120       Loads.insert(LI);
121     } else if (auto *SI = dyn_cast<StoreInst>(&Inst)) {
122       Pointers.insert({SI->getPointerOperand(),
123                        SI->getValueOperand()->getType()});
124       Stores.insert(SI);
125     } else if (auto *CB = dyn_cast<CallBase>(&Inst))
126       Calls.insert(CB);
127   }
128 
129   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
130       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
131     errs() << "Function: " << F.getName() << ": " << Pointers.size()
132            << " pointers, " << Calls.size() << " call sites\n";
133 
134   // iterate over the worklist, and run the full (n^2)/2 disambiguations
135   for (auto I1 = Pointers.begin(), E = Pointers.end(); I1 != E; ++I1) {
136     LocationSize Size1 = LocationSize::precise(DL.getTypeStoreSize(I1->second));
137     for (auto I2 = Pointers.begin(); I2 != I1; ++I2) {
138       LocationSize Size2 =
139           LocationSize::precise(DL.getTypeStoreSize(I2->second));
140       AliasResult AR = AA.alias(I1->first, Size1, I2->first, Size2);
141       switch (AR) {
142       case AliasResult::NoAlias:
143         PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
144         ++NoAliasCount;
145         break;
146       case AliasResult::MayAlias:
147         PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
148         ++MayAliasCount;
149         break;
150       case AliasResult::PartialAlias:
151         PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
152         ++PartialAliasCount;
153         break;
154       case AliasResult::MustAlias:
155         PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
156         ++MustAliasCount;
157         break;
158       }
159     }
160   }
161 
162   if (EvalAAMD) {
163     // iterate over all pairs of load, store
164     for (Value *Load : Loads) {
165       for (Value *Store : Stores) {
166         AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
167                                   MemoryLocation::get(cast<StoreInst>(Store)));
168         switch (AR) {
169         case AliasResult::NoAlias:
170           PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
171           ++NoAliasCount;
172           break;
173         case AliasResult::MayAlias:
174           PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
175           ++MayAliasCount;
176           break;
177         case AliasResult::PartialAlias:
178           PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
179           ++PartialAliasCount;
180           break;
181         case AliasResult::MustAlias:
182           PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
183           ++MustAliasCount;
184           break;
185         }
186       }
187     }
188 
189     // iterate over all pairs of store, store
190     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
191          I1 != E; ++I1) {
192       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
193         AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
194                                   MemoryLocation::get(cast<StoreInst>(*I2)));
195         switch (AR) {
196         case AliasResult::NoAlias:
197           PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
198           ++NoAliasCount;
199           break;
200         case AliasResult::MayAlias:
201           PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
202           ++MayAliasCount;
203           break;
204         case AliasResult::PartialAlias:
205           PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
206           ++PartialAliasCount;
207           break;
208         case AliasResult::MustAlias:
209           PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
210           ++MustAliasCount;
211           break;
212         }
213       }
214     }
215   }
216 
217   // Mod/ref alias analysis: compare all pairs of calls and values
218   for (CallBase *Call : Calls) {
219     for (const auto &Pointer : Pointers) {
220       LocationSize Size =
221           LocationSize::precise(DL.getTypeStoreSize(Pointer.second));
222       switch (AA.getModRefInfo(Call, Pointer.first, Size)) {
223       case ModRefInfo::NoModRef:
224         PrintModRefResults("NoModRef", PrintNoModRef, Call, Pointer,
225                            F.getParent());
226         ++NoModRefCount;
227         break;
228       case ModRefInfo::Mod:
229         PrintModRefResults("Just Mod", PrintMod, Call, Pointer, F.getParent());
230         ++ModCount;
231         break;
232       case ModRefInfo::Ref:
233         PrintModRefResults("Just Ref", PrintRef, Call, Pointer, F.getParent());
234         ++RefCount;
235         break;
236       case ModRefInfo::ModRef:
237         PrintModRefResults("Both ModRef", PrintModRef, Call, Pointer,
238                            F.getParent());
239         ++ModRefCount;
240         break;
241       case ModRefInfo::Must:
242         PrintModRefResults("Must", PrintMust, Call, Pointer, F.getParent());
243         ++MustCount;
244         break;
245       case ModRefInfo::MustMod:
246         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, Call, Pointer,
247                            F.getParent());
248         ++MustModCount;
249         break;
250       case ModRefInfo::MustRef:
251         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, Call, Pointer,
252                            F.getParent());
253         ++MustRefCount;
254         break;
255       case ModRefInfo::MustModRef:
256         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, Call,
257                            Pointer, F.getParent());
258         ++MustModRefCount;
259         break;
260       }
261     }
262   }
263 
264   // Mod/ref alias analysis: compare all pairs of calls
265   for (CallBase *CallA : Calls) {
266     for (CallBase *CallB : Calls) {
267       if (CallA == CallB)
268         continue;
269       switch (AA.getModRefInfo(CallA, CallB)) {
270       case ModRefInfo::NoModRef:
271         PrintModRefResults("NoModRef", PrintNoModRef, CallA, CallB,
272                            F.getParent());
273         ++NoModRefCount;
274         break;
275       case ModRefInfo::Mod:
276         PrintModRefResults("Just Mod", PrintMod, CallA, CallB, F.getParent());
277         ++ModCount;
278         break;
279       case ModRefInfo::Ref:
280         PrintModRefResults("Just Ref", PrintRef, CallA, CallB, F.getParent());
281         ++RefCount;
282         break;
283       case ModRefInfo::ModRef:
284         PrintModRefResults("Both ModRef", PrintModRef, CallA, CallB,
285                            F.getParent());
286         ++ModRefCount;
287         break;
288       case ModRefInfo::Must:
289         PrintModRefResults("Must", PrintMust, CallA, CallB, F.getParent());
290         ++MustCount;
291         break;
292       case ModRefInfo::MustMod:
293         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, CallA, CallB,
294                            F.getParent());
295         ++MustModCount;
296         break;
297       case ModRefInfo::MustRef:
298         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, CallA, CallB,
299                            F.getParent());
300         ++MustRefCount;
301         break;
302       case ModRefInfo::MustModRef:
303         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, CallA,
304                            CallB, F.getParent());
305         ++MustModRefCount;
306         break;
307       }
308     }
309   }
310 }
311 
PrintPercent(int64_t Num,int64_t Sum)312 static void PrintPercent(int64_t Num, int64_t Sum) {
313   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
314          << "%)\n";
315 }
316 
~AAEvaluator()317 AAEvaluator::~AAEvaluator() {
318   if (FunctionCount == 0)
319     return;
320 
321   int64_t AliasSum =
322       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
323   errs() << "===== Alias Analysis Evaluator Report =====\n";
324   if (AliasSum == 0) {
325     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
326   } else {
327     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
328     errs() << "  " << NoAliasCount << " no alias responses ";
329     PrintPercent(NoAliasCount, AliasSum);
330     errs() << "  " << MayAliasCount << " may alias responses ";
331     PrintPercent(MayAliasCount, AliasSum);
332     errs() << "  " << PartialAliasCount << " partial alias responses ";
333     PrintPercent(PartialAliasCount, AliasSum);
334     errs() << "  " << MustAliasCount << " must alias responses ";
335     PrintPercent(MustAliasCount, AliasSum);
336     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
337            << NoAliasCount * 100 / AliasSum << "%/"
338            << MayAliasCount * 100 / AliasSum << "%/"
339            << PartialAliasCount * 100 / AliasSum << "%/"
340            << MustAliasCount * 100 / AliasSum << "%\n";
341   }
342 
343   // Display the summary for mod/ref analysis
344   int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
345                       MustCount + MustRefCount + MustModCount + MustModRefCount;
346   if (ModRefSum == 0) {
347     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
348               "mod/ref!\n";
349   } else {
350     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
351     errs() << "  " << NoModRefCount << " no mod/ref responses ";
352     PrintPercent(NoModRefCount, ModRefSum);
353     errs() << "  " << ModCount << " mod responses ";
354     PrintPercent(ModCount, ModRefSum);
355     errs() << "  " << RefCount << " ref responses ";
356     PrintPercent(RefCount, ModRefSum);
357     errs() << "  " << ModRefCount << " mod & ref responses ";
358     PrintPercent(ModRefCount, ModRefSum);
359     errs() << "  " << MustCount << " must responses ";
360     PrintPercent(MustCount, ModRefSum);
361     errs() << "  " << MustModCount << " must mod responses ";
362     PrintPercent(MustModCount, ModRefSum);
363     errs() << "  " << MustRefCount << " must ref responses ";
364     PrintPercent(MustRefCount, ModRefSum);
365     errs() << "  " << MustModRefCount << " must mod & ref responses ";
366     PrintPercent(MustModRefCount, ModRefSum);
367     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
368            << NoModRefCount * 100 / ModRefSum << "%/"
369            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
370            << "%/" << ModRefCount * 100 / ModRefSum << "%/"
371            << MustCount * 100 / ModRefSum << "%/"
372            << MustRefCount * 100 / ModRefSum << "%/"
373            << MustModCount * 100 / ModRefSum << "%/"
374            << MustModRefCount * 100 / ModRefSum << "%\n";
375   }
376 }
377 
378 namespace llvm {
379 class AAEvalLegacyPass : public FunctionPass {
380   std::unique_ptr<AAEvaluator> P;
381 
382 public:
383   static char ID; // Pass identification, replacement for typeid
AAEvalLegacyPass()384   AAEvalLegacyPass() : FunctionPass(ID) {
385     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
386   }
387 
getAnalysisUsage(AnalysisUsage & AU) const388   void getAnalysisUsage(AnalysisUsage &AU) const override {
389     AU.addRequired<AAResultsWrapperPass>();
390     AU.setPreservesAll();
391   }
392 
doInitialization(Module & M)393   bool doInitialization(Module &M) override {
394     P.reset(new AAEvaluator());
395     return false;
396   }
397 
runOnFunction(Function & F)398   bool runOnFunction(Function &F) override {
399     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
400     return false;
401   }
doFinalization(Module & M)402   bool doFinalization(Module &M) override {
403     P.reset();
404     return false;
405   }
406 };
407 }
408 
409 char AAEvalLegacyPass::ID = 0;
410 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
411                       "Exhaustive Alias Analysis Precision Evaluator", false,
412                       true)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)413 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
414 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
415                     "Exhaustive Alias Analysis Precision Evaluator", false,
416                     true)
417 
418 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
419