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/Module.h"
18 #include "llvm/IR/InstIterator.h"
19 #include "llvm/IR/Instructions.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> PrintMod("print-mod", cl::ReallyHidden);
35 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
36 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
37 
38 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
39 
40 static void PrintResults(const char *Msg, bool P, const Value *V1,
41                          const Value *V2, const Module *M) {
42   if (PrintAll || P) {
43     std::string o1, o2;
44     {
45       raw_string_ostream os1(o1), os2(o2);
46       V1->printAsOperand(os1, true, M);
47       V2->printAsOperand(os2, true, M);
48     }
49 
50     if (o2 < o1)
51       std::swap(o1, o2);
52     errs() << "  " << Msg << ":\t"
53            << o1 << ", "
54            << o2 << "\n";
55   }
56 }
57 
58 static inline void
59 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
60                    Module *M) {
61   if (PrintAll || P) {
62     errs() << "  " << Msg << ":  Ptr: ";
63     Ptr->printAsOperand(errs(), true, M);
64     errs() << "\t<->" << *I << '\n';
65   }
66 }
67 
68 static inline void
69 PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB,
70                    Module *M) {
71   if (PrintAll || P) {
72     errs() << "  " << Msg << ": " << *CSA.getInstruction()
73            << " <-> " << *CSB.getInstruction() << '\n';
74   }
75 }
76 
77 static inline void
78 PrintLoadStoreResults(const char *Msg, bool P, const Value *V1,
79                       const Value *V2, const Module *M) {
80   if (PrintAll || P) {
81     errs() << "  " << Msg << ": " << *V1
82            << " <-> " << *V2 << '\n';
83   }
84 }
85 
86 static inline bool isInterestingPointer(Value *V) {
87   return V->getType()->isPointerTy()
88       && !isa<ConstantPointerNull>(V);
89 }
90 
91 PreservedAnalyses AAEvaluator::run(Function &F, AnalysisManager<Function> &AM) {
92   runInternal(F, AM.getResult<AAManager>(F));
93   return PreservedAnalyses::all();
94 }
95 
96 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
97   const DataLayout &DL = F.getParent()->getDataLayout();
98 
99   ++FunctionCount;
100 
101   SetVector<Value *> Pointers;
102   SmallSetVector<CallSite, 16> CallSites;
103   SetVector<Value *> Loads;
104   SetVector<Value *> Stores;
105 
106   for (auto &I : F.args())
107     if (I.getType()->isPointerTy())    // Add all pointer arguments.
108       Pointers.insert(&I);
109 
110   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
111     if (I->getType()->isPointerTy()) // Add all pointer instructions.
112       Pointers.insert(&*I);
113     if (EvalAAMD && isa<LoadInst>(&*I))
114       Loads.insert(&*I);
115     if (EvalAAMD && isa<StoreInst>(&*I))
116       Stores.insert(&*I);
117     Instruction &Inst = *I;
118     if (auto CS = CallSite(&Inst)) {
119       Value *Callee = CS.getCalledValue();
120       // Skip actual functions for direct function calls.
121       if (!isa<Function>(Callee) && isInterestingPointer(Callee))
122         Pointers.insert(Callee);
123       // Consider formals.
124       for (Use &DataOp : CS.data_ops())
125         if (isInterestingPointer(DataOp))
126           Pointers.insert(DataOp);
127       CallSites.insert(CS);
128     } else {
129       // Consider all operands.
130       for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
131            OI != OE; ++OI)
132         if (isInterestingPointer(*OI))
133           Pointers.insert(*OI);
134     }
135   }
136 
137   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
138       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
139     errs() << "Function: " << F.getName() << ": " << Pointers.size()
140            << " pointers, " << CallSites.size() << " call sites\n";
141 
142   // iterate over the worklist, and run the full (n^2)/2 disambiguations
143   for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
144        I1 != E; ++I1) {
145     uint64_t I1Size = MemoryLocation::UnknownSize;
146     Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
147     if (I1ElTy->isSized()) I1Size = DL.getTypeStoreSize(I1ElTy);
148 
149     for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
150       uint64_t I2Size = MemoryLocation::UnknownSize;
151       Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
152       if (I2ElTy->isSized()) I2Size = DL.getTypeStoreSize(I2ElTy);
153 
154       switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
155       case NoAlias:
156         PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
157         ++NoAliasCount;
158         break;
159       case MayAlias:
160         PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
161         ++MayAliasCount;
162         break;
163       case PartialAlias:
164         PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2,
165                      F.getParent());
166         ++PartialAliasCount;
167         break;
168       case MustAlias:
169         PrintResults("MustAlias", 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 (SetVector<Value *>::iterator I1 = Loads.begin(), E = Loads.end();
179          I1 != E; ++I1) {
180       for (SetVector<Value *>::iterator I2 = Stores.begin(), E2 = Stores.end();
181            I2 != E2; ++I2) {
182         switch (AA.alias(MemoryLocation::get(cast<LoadInst>(*I1)),
183                          MemoryLocation::get(cast<StoreInst>(*I2)))) {
184         case NoAlias:
185           PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
186                                 F.getParent());
187           ++NoAliasCount;
188           break;
189         case MayAlias:
190           PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
191                                 F.getParent());
192           ++MayAliasCount;
193           break;
194         case PartialAlias:
195           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
196                                 F.getParent());
197           ++PartialAliasCount;
198           break;
199         case MustAlias:
200           PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
201                                 F.getParent());
202           ++MustAliasCount;
203           break;
204         }
205       }
206     }
207 
208     // iterate over all pairs of store, store
209     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
210          I1 != E; ++I1) {
211       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
212         switch (AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
213                          MemoryLocation::get(cast<StoreInst>(*I2)))) {
214         case NoAlias:
215           PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
216                                 F.getParent());
217           ++NoAliasCount;
218           break;
219         case MayAlias:
220           PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
221                                 F.getParent());
222           ++MayAliasCount;
223           break;
224         case PartialAlias:
225           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
226                                 F.getParent());
227           ++PartialAliasCount;
228           break;
229         case MustAlias:
230           PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
231                                 F.getParent());
232           ++MustAliasCount;
233           break;
234         }
235       }
236     }
237   }
238 
239   // Mod/ref alias analysis: compare all pairs of calls and values
240   for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
241     Instruction *I = C->getInstruction();
242 
243     for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
244          V != Ve; ++V) {
245       uint64_t Size = MemoryLocation::UnknownSize;
246       Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
247       if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy);
248 
249       switch (AA.getModRefInfo(*C, *V, Size)) {
250       case MRI_NoModRef:
251         PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
252         ++NoModRefCount;
253         break;
254       case MRI_Mod:
255         PrintModRefResults("Just Mod", PrintMod, I, *V, F.getParent());
256         ++ModCount;
257         break;
258       case MRI_Ref:
259         PrintModRefResults("Just Ref", PrintRef, I, *V, F.getParent());
260         ++RefCount;
261         break;
262       case MRI_ModRef:
263         PrintModRefResults("Both ModRef", PrintModRef, I, *V, F.getParent());
264         ++ModRefCount;
265         break;
266       }
267     }
268   }
269 
270   // Mod/ref alias analysis: compare all pairs of calls
271   for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
272     for (auto D = CallSites.begin(); D != Ce; ++D) {
273       if (D == C)
274         continue;
275       switch (AA.getModRefInfo(*C, *D)) {
276       case MRI_NoModRef:
277         PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
278         ++NoModRefCount;
279         break;
280       case MRI_Mod:
281         PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
282         ++ModCount;
283         break;
284       case MRI_Ref:
285         PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
286         ++RefCount;
287         break;
288       case MRI_ModRef:
289         PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
290         ++ModRefCount;
291         break;
292       }
293     }
294   }
295 }
296 
297 static void PrintPercent(int64_t Num, int64_t Sum) {
298   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
299          << "%)\n";
300 }
301 
302 AAEvaluator::~AAEvaluator() {
303   if (FunctionCount == 0)
304     return;
305 
306   int64_t AliasSum =
307       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
308   errs() << "===== Alias Analysis Evaluator Report =====\n";
309   if (AliasSum == 0) {
310     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
311   } else {
312     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
313     errs() << "  " << NoAliasCount << " no alias responses ";
314     PrintPercent(NoAliasCount, AliasSum);
315     errs() << "  " << MayAliasCount << " may alias responses ";
316     PrintPercent(MayAliasCount, AliasSum);
317     errs() << "  " << PartialAliasCount << " partial alias responses ";
318     PrintPercent(PartialAliasCount, AliasSum);
319     errs() << "  " << MustAliasCount << " must alias responses ";
320     PrintPercent(MustAliasCount, AliasSum);
321     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
322            << NoAliasCount * 100 / AliasSum << "%/"
323            << MayAliasCount * 100 / AliasSum << "%/"
324            << PartialAliasCount * 100 / AliasSum << "%/"
325            << MustAliasCount * 100 / AliasSum << "%\n";
326   }
327 
328   // Display the summary for mod/ref analysis
329   int64_t ModRefSum = NoModRefCount + ModCount + RefCount + ModRefCount;
330   if (ModRefSum == 0) {
331     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
332               "mod/ref!\n";
333   } else {
334     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
335     errs() << "  " << NoModRefCount << " no mod/ref responses ";
336     PrintPercent(NoModRefCount, ModRefSum);
337     errs() << "  " << ModCount << " mod responses ";
338     PrintPercent(ModCount, ModRefSum);
339     errs() << "  " << RefCount << " ref responses ";
340     PrintPercent(RefCount, ModRefSum);
341     errs() << "  " << ModRefCount << " mod & ref responses ";
342     PrintPercent(ModRefCount, ModRefSum);
343     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
344            << NoModRefCount * 100 / ModRefSum << "%/"
345            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
346            << "%/" << ModRefCount * 100 / ModRefSum << "%\n";
347   }
348 }
349 
350 namespace llvm {
351 class AAEvalLegacyPass : public FunctionPass {
352   std::unique_ptr<AAEvaluator> P;
353 
354 public:
355   static char ID; // Pass identification, replacement for typeid
356   AAEvalLegacyPass() : FunctionPass(ID) {
357     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
358   }
359 
360   void getAnalysisUsage(AnalysisUsage &AU) const override {
361     AU.addRequired<AAResultsWrapperPass>();
362     AU.setPreservesAll();
363   }
364 
365   bool doInitialization(Module &M) override {
366     P.reset(new AAEvaluator());
367     return false;
368   }
369 
370   bool runOnFunction(Function &F) override {
371     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
372     return false;
373   }
374   bool doFinalization(Module &M) override {
375     P.reset();
376     return false;
377   }
378 };
379 }
380 
381 char AAEvalLegacyPass::ID = 0;
382 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
383                       "Exhaustive Alias Analysis Precision Evaluator", false,
384                       true)
385 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
386 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
387                     "Exhaustive Alias Analysis Precision Evaluator", false,
388                     true)
389 
390 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
391