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/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/Function.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/Pass.h"
25 #include "llvm/Analysis/Passes.h"
26 #include "llvm/Analysis/AliasAnalysis.h"
27 #include "llvm/Assembly/Writer.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/InstIterator.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/ADT/SetVector.h"
35 static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
37 static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
38 static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
39 static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
41 static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
42 static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
43 static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
44 static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
47 class AAEval : public FunctionPass {
48 unsigned NoAlias, MayAlias, MustAlias;
49 unsigned NoModRef, Mod, Ref, ModRef;
52 static char ID; // Pass identification, replacement for typeid
53 AAEval() : FunctionPass(&ID) {}
55 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
56 AU.addRequired<AliasAnalysis>();
60 bool doInitialization(Module &M) {
61 NoAlias = MayAlias = MustAlias = 0;
62 NoModRef = Mod = Ref = ModRef = 0;
65 PrintNoAlias = PrintMayAlias = PrintMustAlias = true;
66 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
71 bool runOnFunction(Function &F);
72 bool doFinalization(Module &M);
77 INITIALIZE_PASS(AAEval, "aa-eval",
78 "Exhaustive Alias Analysis Precision Evaluator", false, true);
80 FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }
82 static void PrintResults(const char *Msg, bool P, const Value *V1,
83 const Value *V2, const Module *M) {
87 raw_string_ostream os1(o1), os2(o2);
88 WriteAsOperand(os1, V1, true, M);
89 WriteAsOperand(os2, V2, true, M);
94 errs() << " " << Msg << ":\t"
101 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
104 errs() << " " << Msg << ": Ptr: ";
105 WriteAsOperand(errs(), Ptr, true, M);
106 errs() << "\t<->" << *I << '\n';
110 static inline bool isInterestingPointer(Value *V) {
111 return V->getType()->isPointerTy()
112 && !isa<ConstantPointerNull>(V);
115 bool AAEval::runOnFunction(Function &F) {
116 AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
118 SetVector<Value *> Pointers;
119 SetVector<CallSite> CallSites;
121 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
122 if (I->getType()->isPointerTy()) // Add all pointer arguments.
125 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
126 if (I->getType()->isPointerTy()) // Add all pointer instructions.
127 Pointers.insert(&*I);
128 Instruction &Inst = *I;
129 if (CallSite CS = cast<Value>(&Inst)) {
130 Value *Callee = CS.getCalledValue();
131 // Skip actual functions for direct function calls.
132 if (!isa<Function>(Callee) && isInterestingPointer(Callee))
133 Pointers.insert(Callee);
135 for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
137 if (isInterestingPointer(*AI))
138 Pointers.insert(*AI);
139 CallSites.insert(CS);
141 // Consider all operands.
142 for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
144 if (isInterestingPointer(*OI))
145 Pointers.insert(*OI);
149 if (PrintNoAlias || PrintMayAlias || PrintMustAlias ||
150 PrintNoModRef || PrintMod || PrintRef || PrintModRef)
151 errs() << "Function: " << F.getName() << ": " << Pointers.size()
152 << " pointers, " << CallSites.size() << " call sites\n";
154 // iterate over the worklist, and run the full (n^2)/2 disambiguations
155 for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
157 unsigned I1Size = ~0u;
158 const Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
159 if (I1ElTy->isSized()) I1Size = AA.getTypeStoreSize(I1ElTy);
161 for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
162 unsigned I2Size = ~0u;
163 const Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
164 if (I2ElTy->isSized()) I2Size = AA.getTypeStoreSize(I2ElTy);
166 switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
167 case AliasAnalysis::NoAlias:
168 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
170 case AliasAnalysis::MayAlias:
171 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
173 case AliasAnalysis::MustAlias:
174 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
177 errs() << "Unknown alias query result!\n";
182 // Mod/ref alias analysis: compare all pairs of calls and values
183 for (SetVector<CallSite>::iterator C = CallSites.begin(),
184 Ce = CallSites.end(); C != Ce; ++C) {
185 Instruction *I = C->getInstruction();
187 for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
190 const Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
191 if (ElTy->isSized()) Size = AA.getTypeStoreSize(ElTy);
193 switch (AA.getModRefInfo(*C, *V, Size)) {
194 case AliasAnalysis::NoModRef:
195 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
197 case AliasAnalysis::Mod:
198 PrintModRefResults(" Mod", PrintMod, I, *V, F.getParent());
200 case AliasAnalysis::Ref:
201 PrintModRefResults(" Ref", PrintRef, I, *V, F.getParent());
203 case AliasAnalysis::ModRef:
204 PrintModRefResults(" ModRef", PrintModRef, I, *V, F.getParent());
207 errs() << "Unknown alias query result!\n";
215 static void PrintPercent(unsigned Num, unsigned Sum) {
216 errs() << "(" << Num*100ULL/Sum << "."
217 << ((Num*1000ULL/Sum) % 10) << "%)\n";
220 bool AAEval::doFinalization(Module &M) {
221 unsigned AliasSum = NoAlias + MayAlias + MustAlias;
222 errs() << "===== Alias Analysis Evaluator Report =====\n";
224 errs() << " Alias Analysis Evaluator Summary: No pointers!\n";
226 errs() << " " << AliasSum << " Total Alias Queries Performed\n";
227 errs() << " " << NoAlias << " no alias responses ";
228 PrintPercent(NoAlias, AliasSum);
229 errs() << " " << MayAlias << " may alias responses ";
230 PrintPercent(MayAlias, AliasSum);
231 errs() << " " << MustAlias << " must alias responses ";
232 PrintPercent(MustAlias, AliasSum);
233 errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
234 << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
235 << MustAlias*100/AliasSum << "%\n";
238 // Display the summary for mod/ref analysis
239 unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
240 if (ModRefSum == 0) {
241 errs() << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
243 errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
244 errs() << " " << NoModRef << " no mod/ref responses ";
245 PrintPercent(NoModRef, ModRefSum);
246 errs() << " " << Mod << " mod responses ";
247 PrintPercent(Mod, ModRefSum);
248 errs() << " " << Ref << " ref responses ";
249 PrintPercent(Ref, ModRefSum);
250 errs() << " " << ModRef << " mod & ref responses ";
251 PrintPercent(ModRef, ModRefSum);
252 errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
253 << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
254 << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";