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(const char *Msg, 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() << "  " << Msg << ":\t"
57            << o1 << ", "
58            << o2 << "\n";
59   }
60 }
61 
62 static inline void
63 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
64                    Module *M) {
65   if (PrintAll || P) {
66     errs() << "  " << Msg << ":  Ptr: ";
67     Ptr->printAsOperand(errs(), true, M);
68     errs() << "\t<->" << *I << '\n';
69   }
70 }
71 
72 static inline void
73 PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB,
74                    Module *M) {
75   if (PrintAll || P) {
76     errs() << "  " << Msg << ": " << *CSA.getInstruction()
77            << " <-> " << *CSB.getInstruction() << '\n';
78   }
79 }
80 
81 static inline void
82 PrintLoadStoreResults(const char *Msg, bool P, const Value *V1,
83                       const Value *V2, const Module *M) {
84   if (PrintAll || P) {
85     errs() << "  " << Msg << ": " << *V1
86            << " <-> " << *V2 << '\n';
87   }
88 }
89 
90 static inline bool isInterestingPointer(Value *V) {
91   return V->getType()->isPointerTy()
92       && !isa<ConstantPointerNull>(V);
93 }
94 
95 PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
96   runInternal(F, AM.getResult<AAManager>(F));
97   return PreservedAnalyses::all();
98 }
99 
100 void AAEvaluator::runInternal(Function &F, AAResults &AA) {
101   const DataLayout &DL = F.getParent()->getDataLayout();
102 
103   ++FunctionCount;
104 
105   SetVector<Value *> Pointers;
106   SmallSetVector<CallSite, 16> CallSites;
107   SetVector<Value *> Loads;
108   SetVector<Value *> Stores;
109 
110   for (auto &I : F.args())
111     if (I.getType()->isPointerTy())    // Add all pointer arguments.
112       Pointers.insert(&I);
113 
114   for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
115     if (I->getType()->isPointerTy()) // Add all pointer instructions.
116       Pointers.insert(&*I);
117     if (EvalAAMD && isa<LoadInst>(&*I))
118       Loads.insert(&*I);
119     if (EvalAAMD && isa<StoreInst>(&*I))
120       Stores.insert(&*I);
121     Instruction &Inst = *I;
122     if (auto CS = CallSite(&Inst)) {
123       Value *Callee = CS.getCalledValue();
124       // Skip actual functions for direct function calls.
125       if (!isa<Function>(Callee) && isInterestingPointer(Callee))
126         Pointers.insert(Callee);
127       // Consider formals.
128       for (Use &DataOp : CS.data_ops())
129         if (isInterestingPointer(DataOp))
130           Pointers.insert(DataOp);
131       CallSites.insert(CS);
132     } else {
133       // Consider all operands.
134       for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
135            OI != OE; ++OI)
136         if (isInterestingPointer(*OI))
137           Pointers.insert(*OI);
138     }
139   }
140 
141   if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
142       PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
143     errs() << "Function: " << F.getName() << ": " << Pointers.size()
144            << " pointers, " << CallSites.size() << " call sites\n";
145 
146   // iterate over the worklist, and run the full (n^2)/2 disambiguations
147   for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
148        I1 != E; ++I1) {
149     uint64_t I1Size = MemoryLocation::UnknownSize;
150     Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
151     if (I1ElTy->isSized()) I1Size = DL.getTypeStoreSize(I1ElTy);
152 
153     for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
154       uint64_t I2Size = MemoryLocation::UnknownSize;
155       Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
156       if (I2ElTy->isSized()) I2Size = DL.getTypeStoreSize(I2ElTy);
157 
158       switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
159       case NoAlias:
160         PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
161         ++NoAliasCount;
162         break;
163       case MayAlias:
164         PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
165         ++MayAliasCount;
166         break;
167       case PartialAlias:
168         PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2,
169                      F.getParent());
170         ++PartialAliasCount;
171         break;
172       case MustAlias:
173         PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
174         ++MustAliasCount;
175         break;
176       }
177     }
178   }
179 
180   if (EvalAAMD) {
181     // iterate over all pairs of load, store
182     for (Value *Load : Loads) {
183       for (Value *Store : Stores) {
184         switch (AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
185                          MemoryLocation::get(cast<StoreInst>(Store)))) {
186         case NoAlias:
187           PrintLoadStoreResults("NoAlias", PrintNoAlias, Load, Store,
188                                 F.getParent());
189           ++NoAliasCount;
190           break;
191         case MayAlias:
192           PrintLoadStoreResults("MayAlias", PrintMayAlias, Load, Store,
193                                 F.getParent());
194           ++MayAliasCount;
195           break;
196         case PartialAlias:
197           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, Load, Store,
198                                 F.getParent());
199           ++PartialAliasCount;
200           break;
201         case MustAlias:
202           PrintLoadStoreResults("MustAlias", PrintMustAlias, Load, Store,
203                                 F.getParent());
204           ++MustAliasCount;
205           break;
206         }
207       }
208     }
209 
210     // iterate over all pairs of store, store
211     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
212          I1 != E; ++I1) {
213       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
214         switch (AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
215                          MemoryLocation::get(cast<StoreInst>(*I2)))) {
216         case NoAlias:
217           PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
218                                 F.getParent());
219           ++NoAliasCount;
220           break;
221         case MayAlias:
222           PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
223                                 F.getParent());
224           ++MayAliasCount;
225           break;
226         case PartialAlias:
227           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
228                                 F.getParent());
229           ++PartialAliasCount;
230           break;
231         case MustAlias:
232           PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
233                                 F.getParent());
234           ++MustAliasCount;
235           break;
236         }
237       }
238     }
239   }
240 
241   // Mod/ref alias analysis: compare all pairs of calls and values
242   for (CallSite C : CallSites) {
243     Instruction *I = C.getInstruction();
244 
245     for (auto Pointer : Pointers) {
246       uint64_t Size = MemoryLocation::UnknownSize;
247       Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
248       if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy);
249 
250       switch (AA.getModRefInfo(C, Pointer, Size)) {
251       case ModRefInfo::NoModRef:
252         PrintModRefResults("NoModRef", PrintNoModRef, I, Pointer,
253                            F.getParent());
254         ++NoModRefCount;
255         break;
256       case ModRefInfo::Mod:
257         PrintModRefResults("Just Mod", PrintMod, I, Pointer, F.getParent());
258         ++ModCount;
259         break;
260       case ModRefInfo::Ref:
261         PrintModRefResults("Just Ref", PrintRef, I, Pointer, F.getParent());
262         ++RefCount;
263         break;
264       case ModRefInfo::ModRef:
265         PrintModRefResults("Both ModRef", PrintModRef, I, Pointer,
266                            F.getParent());
267         ++ModRefCount;
268         break;
269       case ModRefInfo::Must:
270         PrintModRefResults("Must", PrintMust, I, Pointer, F.getParent());
271         ++MustCount;
272         break;
273       case ModRefInfo::MustMod:
274         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, I, Pointer,
275                            F.getParent());
276         ++MustModCount;
277         break;
278       case ModRefInfo::MustRef:
279         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, I, Pointer,
280                            F.getParent());
281         ++MustRefCount;
282         break;
283       case ModRefInfo::MustModRef:
284         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, I,
285                            Pointer, F.getParent());
286         ++MustModRefCount;
287         break;
288       }
289     }
290   }
291 
292   // Mod/ref alias analysis: compare all pairs of calls
293   for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
294     for (auto D = CallSites.begin(); D != Ce; ++D) {
295       if (D == C)
296         continue;
297       switch (AA.getModRefInfo(*C, *D)) {
298       case ModRefInfo::NoModRef:
299         PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
300         ++NoModRefCount;
301         break;
302       case ModRefInfo::Mod:
303         PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
304         ++ModCount;
305         break;
306       case ModRefInfo::Ref:
307         PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
308         ++RefCount;
309         break;
310       case ModRefInfo::ModRef:
311         PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
312         ++ModRefCount;
313         break;
314       case ModRefInfo::Must:
315         PrintModRefResults("Must", PrintMust, *C, *D, F.getParent());
316         ++MustCount;
317         break;
318       case ModRefInfo::MustMod:
319         PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, *C, *D,
320                            F.getParent());
321         ++MustModCount;
322         break;
323       case ModRefInfo::MustRef:
324         PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, *C, *D,
325                            F.getParent());
326         ++MustRefCount;
327         break;
328       case ModRefInfo::MustModRef:
329         PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, *C, *D,
330                            F.getParent());
331         ++MustModRefCount;
332         break;
333       }
334     }
335   }
336 }
337 
338 static void PrintPercent(int64_t Num, int64_t Sum) {
339   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
340          << "%)\n";
341 }
342 
343 AAEvaluator::~AAEvaluator() {
344   if (FunctionCount == 0)
345     return;
346 
347   int64_t AliasSum =
348       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
349   errs() << "===== Alias Analysis Evaluator Report =====\n";
350   if (AliasSum == 0) {
351     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
352   } else {
353     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
354     errs() << "  " << NoAliasCount << " no alias responses ";
355     PrintPercent(NoAliasCount, AliasSum);
356     errs() << "  " << MayAliasCount << " may alias responses ";
357     PrintPercent(MayAliasCount, AliasSum);
358     errs() << "  " << PartialAliasCount << " partial alias responses ";
359     PrintPercent(PartialAliasCount, AliasSum);
360     errs() << "  " << MustAliasCount << " must alias responses ";
361     PrintPercent(MustAliasCount, AliasSum);
362     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
363            << NoAliasCount * 100 / AliasSum << "%/"
364            << MayAliasCount * 100 / AliasSum << "%/"
365            << PartialAliasCount * 100 / AliasSum << "%/"
366            << MustAliasCount * 100 / AliasSum << "%\n";
367   }
368 
369   // Display the summary for mod/ref analysis
370   int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
371                       MustCount + MustRefCount + MustModCount + MustModRefCount;
372   if (ModRefSum == 0) {
373     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
374               "mod/ref!\n";
375   } else {
376     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
377     errs() << "  " << NoModRefCount << " no mod/ref responses ";
378     PrintPercent(NoModRefCount, ModRefSum);
379     errs() << "  " << ModCount << " mod responses ";
380     PrintPercent(ModCount, ModRefSum);
381     errs() << "  " << RefCount << " ref responses ";
382     PrintPercent(RefCount, ModRefSum);
383     errs() << "  " << ModRefCount << " mod & ref responses ";
384     PrintPercent(ModRefCount, ModRefSum);
385     errs() << "  " << MustCount << " must responses ";
386     PrintPercent(MustCount, ModRefSum);
387     errs() << "  " << MustModCount << " must mod responses ";
388     PrintPercent(MustModCount, ModRefSum);
389     errs() << "  " << MustRefCount << " must ref responses ";
390     PrintPercent(MustRefCount, ModRefSum);
391     errs() << "  " << MustModRefCount << " must mod & ref responses ";
392     PrintPercent(MustModRefCount, ModRefSum);
393     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
394            << NoModRefCount * 100 / ModRefSum << "%/"
395            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
396            << "%/" << ModRefCount * 100 / ModRefSum << "%/"
397            << MustCount * 100 / ModRefSum << "%/"
398            << MustRefCount * 100 / ModRefSum << "%/"
399            << MustModCount * 100 / ModRefSum << "%/"
400            << MustModRefCount * 100 / ModRefSum << "%\n";
401   }
402 }
403 
404 namespace llvm {
405 class AAEvalLegacyPass : public FunctionPass {
406   std::unique_ptr<AAEvaluator> P;
407 
408 public:
409   static char ID; // Pass identification, replacement for typeid
410   AAEvalLegacyPass() : FunctionPass(ID) {
411     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
412   }
413 
414   void getAnalysisUsage(AnalysisUsage &AU) const override {
415     AU.addRequired<AAResultsWrapperPass>();
416     AU.setPreservesAll();
417   }
418 
419   bool doInitialization(Module &M) override {
420     P.reset(new AAEvaluator());
421     return false;
422   }
423 
424   bool runOnFunction(Function &F) override {
425     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
426     return false;
427   }
428   bool doFinalization(Module &M) override {
429     P.reset();
430     return false;
431   }
432 };
433 }
434 
435 char AAEvalLegacyPass::ID = 0;
436 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
437                       "Exhaustive Alias Analysis Precision Evaluator", false,
438                       true)
439 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
440 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
441                     "Exhaustive Alias Analysis Precision Evaluator", false,
442                     true)
443 
444 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
445