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 
PrintResults(const char * Msg,bool P,const Value * V1,const Value * V2,const Module * M)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
PrintModRefResults(const char * Msg,bool P,Instruction * I,Value * Ptr,Module * M)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
PrintModRefResults(const char * Msg,bool P,CallSite CSA,CallSite CSB,Module * M)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
PrintLoadStoreResults(const char * Msg,bool P,const Value * V1,const Value * V2,const Module * M)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 
isInterestingPointer(Value * V)86 static inline bool isInterestingPointer(Value *V) {
87   return V->getType()->isPointerTy()
88       && !isa<ConstantPointerNull>(V);
89 }
90 
run(Function & F,AnalysisManager<Function> & AM)91 PreservedAnalyses AAEvaluator::run(Function &F, AnalysisManager<Function> &AM) {
92   runInternal(F, AM.getResult<AAManager>(F));
93   return PreservedAnalyses::all();
94 }
95 
runInternal(Function & F,AAResults & AA)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 (Value *Load : Loads) {
179       for (Value *Store : Stores) {
180         switch (AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
181                          MemoryLocation::get(cast<StoreInst>(Store)))) {
182         case NoAlias:
183           PrintLoadStoreResults("NoAlias", PrintNoAlias, Load, Store,
184                                 F.getParent());
185           ++NoAliasCount;
186           break;
187         case MayAlias:
188           PrintLoadStoreResults("MayAlias", PrintMayAlias, Load, Store,
189                                 F.getParent());
190           ++MayAliasCount;
191           break;
192         case PartialAlias:
193           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, Load, Store,
194                                 F.getParent());
195           ++PartialAliasCount;
196           break;
197         case MustAlias:
198           PrintLoadStoreResults("MustAlias", PrintMustAlias, Load, Store,
199                                 F.getParent());
200           ++MustAliasCount;
201           break;
202         }
203       }
204     }
205 
206     // iterate over all pairs of store, store
207     for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
208          I1 != E; ++I1) {
209       for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
210         switch (AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
211                          MemoryLocation::get(cast<StoreInst>(*I2)))) {
212         case NoAlias:
213           PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
214                                 F.getParent());
215           ++NoAliasCount;
216           break;
217         case MayAlias:
218           PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
219                                 F.getParent());
220           ++MayAliasCount;
221           break;
222         case PartialAlias:
223           PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
224                                 F.getParent());
225           ++PartialAliasCount;
226           break;
227         case MustAlias:
228           PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
229                                 F.getParent());
230           ++MustAliasCount;
231           break;
232         }
233       }
234     }
235   }
236 
237   // Mod/ref alias analysis: compare all pairs of calls and values
238   for (CallSite C : CallSites) {
239     Instruction *I = C.getInstruction();
240 
241     for (auto Pointer : Pointers) {
242       uint64_t Size = MemoryLocation::UnknownSize;
243       Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
244       if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy);
245 
246       switch (AA.getModRefInfo(C, Pointer, Size)) {
247       case MRI_NoModRef:
248         PrintModRefResults("NoModRef", PrintNoModRef, I, Pointer,
249                            F.getParent());
250         ++NoModRefCount;
251         break;
252       case MRI_Mod:
253         PrintModRefResults("Just Mod", PrintMod, I, Pointer, F.getParent());
254         ++ModCount;
255         break;
256       case MRI_Ref:
257         PrintModRefResults("Just Ref", PrintRef, I, Pointer, F.getParent());
258         ++RefCount;
259         break;
260       case MRI_ModRef:
261         PrintModRefResults("Both ModRef", PrintModRef, I, Pointer,
262                            F.getParent());
263         ++ModRefCount;
264         break;
265       }
266     }
267   }
268 
269   // Mod/ref alias analysis: compare all pairs of calls
270   for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
271     for (auto D = CallSites.begin(); D != Ce; ++D) {
272       if (D == C)
273         continue;
274       switch (AA.getModRefInfo(*C, *D)) {
275       case MRI_NoModRef:
276         PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
277         ++NoModRefCount;
278         break;
279       case MRI_Mod:
280         PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
281         ++ModCount;
282         break;
283       case MRI_Ref:
284         PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
285         ++RefCount;
286         break;
287       case MRI_ModRef:
288         PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
289         ++ModRefCount;
290         break;
291       }
292     }
293   }
294 }
295 
PrintPercent(int64_t Num,int64_t Sum)296 static void PrintPercent(int64_t Num, int64_t Sum) {
297   errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
298          << "%)\n";
299 }
300 
~AAEvaluator()301 AAEvaluator::~AAEvaluator() {
302   if (FunctionCount == 0)
303     return;
304 
305   int64_t AliasSum =
306       NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
307   errs() << "===== Alias Analysis Evaluator Report =====\n";
308   if (AliasSum == 0) {
309     errs() << "  Alias Analysis Evaluator Summary: No pointers!\n";
310   } else {
311     errs() << "  " << AliasSum << " Total Alias Queries Performed\n";
312     errs() << "  " << NoAliasCount << " no alias responses ";
313     PrintPercent(NoAliasCount, AliasSum);
314     errs() << "  " << MayAliasCount << " may alias responses ";
315     PrintPercent(MayAliasCount, AliasSum);
316     errs() << "  " << PartialAliasCount << " partial alias responses ";
317     PrintPercent(PartialAliasCount, AliasSum);
318     errs() << "  " << MustAliasCount << " must alias responses ";
319     PrintPercent(MustAliasCount, AliasSum);
320     errs() << "  Alias Analysis Evaluator Pointer Alias Summary: "
321            << NoAliasCount * 100 / AliasSum << "%/"
322            << MayAliasCount * 100 / AliasSum << "%/"
323            << PartialAliasCount * 100 / AliasSum << "%/"
324            << MustAliasCount * 100 / AliasSum << "%\n";
325   }
326 
327   // Display the summary for mod/ref analysis
328   int64_t ModRefSum = NoModRefCount + ModCount + RefCount + ModRefCount;
329   if (ModRefSum == 0) {
330     errs() << "  Alias Analysis Mod/Ref Evaluator Summary: no "
331               "mod/ref!\n";
332   } else {
333     errs() << "  " << ModRefSum << " Total ModRef Queries Performed\n";
334     errs() << "  " << NoModRefCount << " no mod/ref responses ";
335     PrintPercent(NoModRefCount, ModRefSum);
336     errs() << "  " << ModCount << " mod responses ";
337     PrintPercent(ModCount, ModRefSum);
338     errs() << "  " << RefCount << " ref responses ";
339     PrintPercent(RefCount, ModRefSum);
340     errs() << "  " << ModRefCount << " mod & ref responses ";
341     PrintPercent(ModRefCount, ModRefSum);
342     errs() << "  Alias Analysis Evaluator Mod/Ref Summary: "
343            << NoModRefCount * 100 / ModRefSum << "%/"
344            << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
345            << "%/" << ModRefCount * 100 / ModRefSum << "%\n";
346   }
347 }
348 
349 namespace llvm {
350 class AAEvalLegacyPass : public FunctionPass {
351   std::unique_ptr<AAEvaluator> P;
352 
353 public:
354   static char ID; // Pass identification, replacement for typeid
AAEvalLegacyPass()355   AAEvalLegacyPass() : FunctionPass(ID) {
356     initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
357   }
358 
getAnalysisUsage(AnalysisUsage & AU) const359   void getAnalysisUsage(AnalysisUsage &AU) const override {
360     AU.addRequired<AAResultsWrapperPass>();
361     AU.setPreservesAll();
362   }
363 
doInitialization(Module & M)364   bool doInitialization(Module &M) override {
365     P.reset(new AAEvaluator());
366     return false;
367   }
368 
runOnFunction(Function & F)369   bool runOnFunction(Function &F) override {
370     P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
371     return false;
372   }
doFinalization(Module & M)373   bool doFinalization(Module &M) override {
374     P.reset();
375     return false;
376   }
377 };
378 }
379 
380 char AAEvalLegacyPass::ID = 0;
381 INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
382                       "Exhaustive Alias Analysis Precision Evaluator", false,
383                       true)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)384 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
385 INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
386                     "Exhaustive Alias Analysis Precision Evaluator", false,
387                     true)
388 
389 FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }
390