1 //===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/Analysis/AliasAnalysisEvaluator.h"
11 #include "llvm/ADT/SetVector.h"
12 #include "llvm/Analysis/AliasAnalysis.h"
13 #include "llvm/IR/Constants.h"
14 #include "llvm/IR/DataLayout.h"
15 #include "llvm/IR/DerivedTypes.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/IR/InstIterator.h"
18 #include "llvm/IR/Instructions.h"
19 #include "llvm/IR/Module.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 
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 
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 
69 static inline void PrintModRefResults(const char *Msg, bool P, CallSite CSA,
70                                       CallSite CSB, Module *M) {
71   if (PrintAll || P) {
72     errs() << "  " << Msg << ": " << *CSA.getInstruction() << " <-> "
73            << *CSB.getInstruction() << '\n';
74   }
75 }
76 
77 static inline void PrintLoadStoreResults(AliasResult AR, bool P,
78                                          const Value *V1, const Value *V2,
79                                          const Module *M) {
80   if (PrintAll || P) {
81     errs() << "  " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
82   }
83 }
84 
85 static inline bool isInterestingPointer(Value *V) {
86   return V->getType()->isPointerTy()
87       && !isa<ConstantPointerNull>(V);
88 }
89 
90 PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
91   runInternal(F, AM.getResult<AAManager>(F));
92   return PreservedAnalyses::all();
93 }
94 
95 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
96   const DataLayout &DL = F.getParent()->getDataLayout();
97 
98   ++FunctionCount;
99 
100   SetVector<Value *> Pointers;
101   SmallSetVector<CallSite, 16> CallSites;
102   SetVector<Value *> Loads;
103   SetVector<Value *> Stores;
104 
105   for (auto &I : F.args())
106     if (I.getType()->isPointerTy())    // Add all pointer arguments.
107       Pointers.insert(&I);
108 
109   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
110     if (I->getType()->isPointerTy()) // Add all pointer instructions.
111       Pointers.insert(&*I);
112     if (EvalAAMD && isa<LoadInst>(&*I))
113       Loads.insert(&*I);
114     if (EvalAAMD && isa<StoreInst>(&*I))
115       Stores.insert(&*I);
116     Instruction &Inst = *I;
117     if (auto CS = CallSite(&Inst)) {
118       Value *Callee = CS.getCalledValue();
119       // Skip actual functions for direct function calls.
120       if (!isa<Function>(Callee) && isInterestingPointer(Callee))
121         Pointers.insert(Callee);
122       // Consider formals.
123       for (Use &DataOp : CS.data_ops())
124         if (isInterestingPointer(DataOp))
125           Pointers.insert(DataOp);
126       CallSites.insert(CS);
127     } else {
128       // Consider all operands.
129       for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
130            OI != OE; ++OI)
131         if (isInterestingPointer(*OI))
132           Pointers.insert(*OI);
133     }
134   }
135 
136   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
137       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
138     errs() << "Function: " << F.getName() << ": " << Pointers.size()
139            << " pointers, " << CallSites.size() << " call sites\n";
140 
141   // iterate over the worklist, and run the full (n^2)/2 disambiguations
142   for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
143        I1 != E; ++I1) {
144     uint64_t I1Size = MemoryLocation::UnknownSize;
145     Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
146     if (I1ElTy->isSized()) I1Size = DL.getTypeStoreSize(I1ElTy);
147 
148     for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
149       uint64_t I2Size = MemoryLocation::UnknownSize;
150       Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
151       if (I2ElTy->isSized()) I2Size = DL.getTypeStoreSize(I2ElTy);
152 
153       AliasResult AR = AA.alias(*I1, I1Size, *I2, I2Size);
154       switch (AR) {
155       case NoAlias:
156         PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
157         ++NoAliasCount;
158         break;
159       case MayAlias:
160         PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
161         ++MayAliasCount;
162         break;
163       case PartialAlias:
164         PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
165         ++PartialAliasCount;
166         break;
167       case MustAlias:
168         PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
169         ++MustAliasCount;
170         break;
171       }
172     }
173   }
174 
175   if (EvalAAMD) {
176     // iterate over all pairs of load, store
177     for (Value *Load : Loads) {
178       for (Value *Store : Stores) {
179         AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
180                                   MemoryLocation::get(cast<StoreInst>(Store)));
181         switch (AR) {
182         case NoAlias:
183           PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
184           ++NoAliasCount;
185           break;
186         case MayAlias:
187           PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
188           ++MayAliasCount;
189           break;
190         case PartialAlias:
191           PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
192           ++PartialAliasCount;
193           break;
194         case MustAlias:
195           PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
196           ++MustAliasCount;
197           break;
198         }
199       }
200     }
201 
202     // iterate over all pairs of store, store
203     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
204          I1 != E; ++I1) {
205       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
206         AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
207                                   MemoryLocation::get(cast<StoreInst>(*I2)));
208         switch (AR) {
209         case NoAlias:
210           PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
211           ++NoAliasCount;
212           break;
213         case MayAlias:
214           PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
215           ++MayAliasCount;
216           break;
217         case PartialAlias:
218           PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
219           ++PartialAliasCount;
220           break;
221         case MustAlias:
222           PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
223           ++MustAliasCount;
224           break;
225         }
226       }
227     }
228   }
229 
230   // Mod/ref alias analysis: compare all pairs of calls and values
231   for (CallSite C : CallSites) {
232     Instruction *I = C.getInstruction();
233 
234     for (auto Pointer : Pointers) {
235       uint64_t Size = MemoryLocation::UnknownSize;
236       Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
237       if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy);
238 
239       switch (AA.getModRefInfo(C, Pointer, Size)) {
240       case ModRefInfo::NoModRef:
241         PrintModRefResults("NoModRef", PrintNoModRef, I, Pointer,
242                            F.getParent());
243         ++NoModRefCount;
244         break;
245       case ModRefInfo::Mod:
246         PrintModRefResults("Just Mod", PrintMod, I, Pointer, F.getParent());
247         ++ModCount;
248         break;
249       case ModRefInfo::Ref:
250         PrintModRefResults("Just Ref", PrintRef, I, Pointer, F.getParent());
251         ++RefCount;
252         break;
253       case ModRefInfo::ModRef:
254         PrintModRefResults("Both ModRef", PrintModRef, I, Pointer,
255                            F.getParent());
256         ++ModRefCount;
257         break;
258       case ModRefInfo::Must:
259         PrintModRefResults("Must", PrintMust, I, Pointer, F.getParent());
260         ++MustCount;
261         break;
262       case ModRefInfo::MustMod:
263         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, I, Pointer,
264                            F.getParent());
265         ++MustModCount;
266         break;
267       case ModRefInfo::MustRef:
268         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, I, Pointer,
269                            F.getParent());
270         ++MustRefCount;
271         break;
272       case ModRefInfo::MustModRef:
273         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, I,
274                            Pointer, F.getParent());
275         ++MustModRefCount;
276         break;
277       }
278     }
279   }
280 
281   // Mod/ref alias analysis: compare all pairs of calls
282   for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
283     for (auto D = CallSites.begin(); D != Ce; ++D) {
284       if (D == C)
285         continue;
286       switch (AA.getModRefInfo(*C, *D)) {
287       case ModRefInfo::NoModRef:
288         PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
289         ++NoModRefCount;
290         break;
291       case ModRefInfo::Mod:
292         PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
293         ++ModCount;
294         break;
295       case ModRefInfo::Ref:
296         PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
297         ++RefCount;
298         break;
299       case ModRefInfo::ModRef:
300         PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
301         ++ModRefCount;
302         break;
303       case ModRefInfo::Must:
304         PrintModRefResults("Must", PrintMust, *C, *D, F.getParent());
305         ++MustCount;
306         break;
307       case ModRefInfo::MustMod:
308         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, *C, *D,
309                            F.getParent());
310         ++MustModCount;
311         break;
312       case ModRefInfo::MustRef:
313         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, *C, *D,
314                            F.getParent());
315         ++MustRefCount;
316         break;
317       case ModRefInfo::MustModRef:
318         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, *C, *D,
319                            F.getParent());
320         ++MustModRefCount;
321         break;
322       }
323     }
324   }
325 }
326 
327 static void PrintPercent(int64_t Num, int64_t Sum) {
328   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
329          << "%)\n";
330 }
331 
332 AAEvaluator::~AAEvaluator() {
333   if (FunctionCount == 0)
334     return;
335 
336   int64_t AliasSum =
337       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
338   errs() << "===== Alias Analysis Evaluator Report =====\n";
339   if (AliasSum == 0) {
340     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
341   } else {
342     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
343     errs() << "  " << NoAliasCount << " no alias responses ";
344     PrintPercent(NoAliasCount, AliasSum);
345     errs() << "  " << MayAliasCount << " may alias responses ";
346     PrintPercent(MayAliasCount, AliasSum);
347     errs() << "  " << PartialAliasCount << " partial alias responses ";
348     PrintPercent(PartialAliasCount, AliasSum);
349     errs() << "  " << MustAliasCount << " must alias responses ";
350     PrintPercent(MustAliasCount, AliasSum);
351     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
352            << NoAliasCount * 100 / AliasSum << "%/"
353            << MayAliasCount * 100 / AliasSum << "%/"
354            << PartialAliasCount * 100 / AliasSum << "%/"
355            << MustAliasCount * 100 / AliasSum << "%\n";
356   }
357 
358   // Display the summary for mod/ref analysis
359   int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
360                       MustCount + MustRefCount + MustModCount + MustModRefCount;
361   if (ModRefSum == 0) {
362     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
363               "mod/ref!\n";
364   } else {
365     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
366     errs() << "  " << NoModRefCount << " no mod/ref responses ";
367     PrintPercent(NoModRefCount, ModRefSum);
368     errs() << "  " << ModCount << " mod responses ";
369     PrintPercent(ModCount, ModRefSum);
370     errs() << "  " << RefCount << " ref responses ";
371     PrintPercent(RefCount, ModRefSum);
372     errs() << "  " << ModRefCount << " mod & ref responses ";
373     PrintPercent(ModRefCount, ModRefSum);
374     errs() << "  " << MustCount << " must responses ";
375     PrintPercent(MustCount, ModRefSum);
376     errs() << "  " << MustModCount << " must mod responses ";
377     PrintPercent(MustModCount, ModRefSum);
378     errs() << "  " << MustRefCount << " must ref responses ";
379     PrintPercent(MustRefCount, ModRefSum);
380     errs() << "  " << MustModRefCount << " must mod & ref responses ";
381     PrintPercent(MustModRefCount, ModRefSum);
382     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
383            << NoModRefCount * 100 / ModRefSum << "%/"
384            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
385            << "%/" << ModRefCount * 100 / ModRefSum << "%/"
386            << MustCount * 100 / ModRefSum << "%/"
387            << MustRefCount * 100 / ModRefSum << "%/"
388            << MustModCount * 100 / ModRefSum << "%/"
389            << MustModRefCount * 100 / ModRefSum << "%\n";
390   }
391 }
392 
393 namespace llvm {
394 class AAEvalLegacyPass : public FunctionPass {
395   std::unique_ptr<AAEvaluator> P;
396 
397 public:
398   static char ID; // Pass identification, replacement for typeid
399   AAEvalLegacyPass() : FunctionPass(ID) {
400     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
401   }
402 
403   void getAnalysisUsage(AnalysisUsage &AU) const override {
404     AU.addRequired<AAResultsWrapperPass>();
405     AU.setPreservesAll();
406   }
407 
408   bool doInitialization(Module &M) override {
409     P.reset(new AAEvaluator());
410     return false;
411   }
412 
413   bool runOnFunction(Function &F) override {
414     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
415     return false;
416   }
417   bool doFinalization(Module &M) override {
418     P.reset();
419     return false;
420   }
421 };
422 }
423 
424 char AAEvalLegacyPass::ID = 0;
425 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
426                       "Exhaustive Alias Analysis Precision Evaluator", false,
427                       true)
428 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
429 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
430                     "Exhaustive Alias Analysis Precision Evaluator", false,
431                     true)
432 
433 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
434