1 //===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements a simple N^2 alias analysis accuracy evaluator.
11 // Basically, for each function in the program, it simply queries to see how the
12 // alias analysis implementation answers alias queries between each pair of
13 // pointers in the function.
15 // This is inspired and adapted from code by: Naveen Neelakantam, Francesco
16 // Spadini, and Wojciech Stryjewski.
18 //===----------------------------------------------------------------------===//
20 #include "llvm/Analysis/Passes.h"
21 #include "llvm/ADT/SetVector.h"
22 #include "llvm/Analysis/AliasAnalysis.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/IR/DataLayout.h"
25 #include "llvm/IR/DerivedTypes.h"
26 #include "llvm/IR/Function.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/InstIterator.h"
29 #include "llvm/IR/Instructions.h"
30 #include "llvm/Pass.h"
31 #include "llvm/Support/CommandLine.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/raw_ostream.h"
36 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
38 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
39 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
40 static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
41 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
43 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
44 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
45 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
46 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
48 static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
51 class AAEval : public FunctionPass {
52 unsigned NoAliasCount, MayAliasCount, PartialAliasCount, MustAliasCount;
53 unsigned NoModRefCount, ModCount, RefCount, ModRefCount;
56 static char ID; // Pass identification, replacement for typeid
57 AAEval() : FunctionPass(ID) {
58 initializeAAEvalPass(*PassRegistry::getPassRegistry());
61 void getAnalysisUsage(AnalysisUsage &AU) const override {
62 AU.addRequired<AAResultsWrapperPass>();
66 bool doInitialization(Module &M) override {
67 NoAliasCount = MayAliasCount = PartialAliasCount = MustAliasCount = 0;
68 NoModRefCount = ModCount = RefCount = ModRefCount = 0;
71 PrintNoAlias = PrintMayAlias = true;
72 PrintPartialAlias = PrintMustAlias = true;
73 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
78 bool runOnFunction(Function &F) override;
79 bool doFinalization(Module &M) override;
84 INITIALIZE_PASS_BEGIN(AAEval, "aa-eval",
85 "Exhaustive Alias Analysis Precision Evaluator", false, true)
86 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
87 INITIALIZE_PASS_END(AAEval, "aa-eval",
88 "Exhaustive Alias Analysis Precision Evaluator", false, true)
90 FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }
92 static void PrintResults(const char *Msg, bool P, const Value *V1,
93 const Value *V2, const Module *M) {
97 raw_string_ostream os1(o1), os2(o2);
98 V1->printAsOperand(os1, true, M);
99 V2->printAsOperand(os2, true, M);
104 errs() << " " << Msg << ":\t"
111 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
114 errs() << " " << Msg << ": Ptr: ";
115 Ptr->printAsOperand(errs(), true, M);
116 errs() << "\t<->" << *I << '\n';
121 PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB,
124 errs() << " " << Msg << ": " << *CSA.getInstruction()
125 << " <-> " << *CSB.getInstruction() << '\n';
130 PrintLoadStoreResults(const char *Msg, bool P, const Value *V1,
131 const Value *V2, const Module *M) {
133 errs() << " " << Msg << ": " << *V1
134 << " <-> " << *V2 << '\n';
138 static inline bool isInterestingPointer(Value *V) {
139 return V->getType()->isPointerTy()
140 && !isa<ConstantPointerNull>(V);
143 bool AAEval::runOnFunction(Function &F) {
144 const DataLayout &DL = F.getParent()->getDataLayout();
145 AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
147 SetVector<Value *> Pointers;
148 SmallSetVector<CallSite, 16> CallSites;
149 SetVector<Value *> Loads;
150 SetVector<Value *> Stores;
152 for (auto &I : F.args())
153 if (I.getType()->isPointerTy()) // Add all pointer arguments.
156 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
157 if (I->getType()->isPointerTy()) // Add all pointer instructions.
158 Pointers.insert(&*I);
159 if (EvalAAMD && isa<LoadInst>(&*I))
161 if (EvalAAMD && isa<StoreInst>(&*I))
163 Instruction &Inst = *I;
164 if (auto CS = CallSite(&Inst)) {
165 Value *Callee = CS.getCalledValue();
166 // Skip actual functions for direct function calls.
167 if (!isa<Function>(Callee) && isInterestingPointer(Callee))
168 Pointers.insert(Callee);
170 for (Use &DataOp : CS.data_ops())
171 if (isInterestingPointer(DataOp))
172 Pointers.insert(DataOp);
173 CallSites.insert(CS);
175 // Consider all operands.
176 for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
178 if (isInterestingPointer(*OI))
179 Pointers.insert(*OI);
183 if (PrintNoAlias || PrintMayAlias || PrintPartialAlias || PrintMustAlias ||
184 PrintNoModRef || PrintMod || PrintRef || PrintModRef)
185 errs() << "Function: " << F.getName() << ": " << Pointers.size()
186 << " pointers, " << CallSites.size() << " call sites\n";
188 // iterate over the worklist, and run the full (n^2)/2 disambiguations
189 for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
191 uint64_t I1Size = MemoryLocation::UnknownSize;
192 Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
193 if (I1ElTy->isSized()) I1Size = DL.getTypeStoreSize(I1ElTy);
195 for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
196 uint64_t I2Size = MemoryLocation::UnknownSize;
197 Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
198 if (I2ElTy->isSized()) I2Size = DL.getTypeStoreSize(I2ElTy);
200 switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
202 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
206 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
210 PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2,
215 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
223 // iterate over all pairs of load, store
224 for (SetVector<Value *>::iterator I1 = Loads.begin(), E = Loads.end();
226 for (SetVector<Value *>::iterator I2 = Stores.begin(), E2 = Stores.end();
228 switch (AA.alias(MemoryLocation::get(cast<LoadInst>(*I1)),
229 MemoryLocation::get(cast<StoreInst>(*I2)))) {
231 PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
236 PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
241 PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
246 PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
254 // iterate over all pairs of store, store
255 for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
257 for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
258 switch (AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
259 MemoryLocation::get(cast<StoreInst>(*I2)))) {
261 PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
266 PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
271 PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
276 PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
285 // Mod/ref alias analysis: compare all pairs of calls and values
286 for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
287 Instruction *I = C->getInstruction();
289 for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
291 uint64_t Size = MemoryLocation::UnknownSize;
292 Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
293 if (ElTy->isSized()) Size = DL.getTypeStoreSize(ElTy);
295 switch (AA.getModRefInfo(*C, *V, Size)) {
297 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
301 PrintModRefResults("Just Mod", PrintMod, I, *V, F.getParent());
305 PrintModRefResults("Just Ref", PrintRef, I, *V, F.getParent());
309 PrintModRefResults("Both ModRef", PrintModRef, I, *V, F.getParent());
316 // Mod/ref alias analysis: compare all pairs of calls
317 for (auto C = CallSites.begin(), Ce = CallSites.end(); C != Ce; ++C) {
318 for (auto D = CallSites.begin(); D != Ce; ++D) {
321 switch (AA.getModRefInfo(*C, *D)) {
323 PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
327 PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
331 PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
335 PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
345 static void PrintPercent(unsigned Num, unsigned Sum) {
346 errs() << "(" << Num*100ULL/Sum << "."
347 << ((Num*1000ULL/Sum) % 10) << "%)\n";
350 bool AAEval::doFinalization(Module &M) {
352 NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
353 errs() << "===== Alias Analysis Evaluator Report =====\n";
355 errs() << " Alias Analysis Evaluator Summary: No pointers!\n";
357 errs() << " " << AliasSum << " Total Alias Queries Performed\n";
358 errs() << " " << NoAliasCount << " no alias responses ";
359 PrintPercent(NoAliasCount, AliasSum);
360 errs() << " " << MayAliasCount << " may alias responses ";
361 PrintPercent(MayAliasCount, AliasSum);
362 errs() << " " << PartialAliasCount << " partial alias responses ";
363 PrintPercent(PartialAliasCount, AliasSum);
364 errs() << " " << MustAliasCount << " must alias responses ";
365 PrintPercent(MustAliasCount, AliasSum);
366 errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
367 << NoAliasCount * 100 / AliasSum << "%/"
368 << MayAliasCount * 100 / AliasSum << "%/"
369 << PartialAliasCount * 100 / AliasSum << "%/"
370 << MustAliasCount * 100 / AliasSum << "%\n";
373 // Display the summary for mod/ref analysis
374 unsigned ModRefSum = NoModRefCount + ModCount + RefCount + ModRefCount;
375 if (ModRefSum == 0) {
376 errs() << " Alias Analysis Mod/Ref Evaluator Summary: no "
379 errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
380 errs() << " " << NoModRefCount << " no mod/ref responses ";
381 PrintPercent(NoModRefCount, ModRefSum);
382 errs() << " " << ModCount << " mod responses ";
383 PrintPercent(ModCount, ModRefSum);
384 errs() << " " << RefCount << " ref responses ";
385 PrintPercent(RefCount, ModRefSum);
386 errs() << " " << ModRefCount << " mod & ref responses ";
387 PrintPercent(ModRefCount, ModRefSum);
388 errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
389 << NoModRefCount * 100 / ModRefSum << "%/"
390 << ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
391 << "%/" << ModRefCount * 100 / ModRefSum << "%\n";