1 //===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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/Target/TargetData.h"
29 #include "llvm/Support/InstIterator.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Support/Compiler.h"
32 #include "llvm/Support/Streams.h"
37 cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
39 cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
40 cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
41 cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
43 cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
44 cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
45 cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
46 cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
48 class VISIBILITY_HIDDEN AAEval : public FunctionPass {
49 unsigned NoAlias, MayAlias, MustAlias;
50 unsigned NoModRef, Mod, Ref, ModRef;
53 static char ID; // Pass identification, replacement for typeid
54 AAEval() : FunctionPass((intptr_t)&ID) {}
56 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
57 AU.addRequired<AliasAnalysis>();
61 bool doInitialization(Module &M) {
62 NoAlias = MayAlias = MustAlias = 0;
63 NoModRef = Mod = Ref = ModRef = 0;
66 PrintNoAlias = PrintMayAlias = PrintMustAlias = true;
67 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
72 bool runOnFunction(Function &F);
73 bool doFinalization(Module &M);
78 X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator");
81 FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }
83 static inline void PrintResults(const char *Msg, bool P, Value *V1, Value *V2,
86 cerr << " " << Msg << ":\t";
87 WriteAsOperand(*cerr.stream(), V1, true, M) << ", ";
88 WriteAsOperand(*cerr.stream(), V2, true, M) << "\n";
93 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
96 cerr << " " << Msg << ": Ptr: ";
97 WriteAsOperand(*cerr.stream(), Ptr, true, M);
98 cerr << "\t<->" << *I;
102 bool AAEval::runOnFunction(Function &F) {
103 AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
105 const TargetData &TD = AA.getTargetData();
107 std::set<Value *> Pointers;
108 std::set<CallSite> CallSites;
110 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
111 if (isa<PointerType>(I->getType())) // Add all pointer arguments
114 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
115 if (isa<PointerType>(I->getType())) // Add all pointer instructions
116 Pointers.insert(&*I);
117 Instruction &Inst = *I;
118 User::op_iterator OI = Inst.op_begin();
119 if ((isa<InvokeInst>(Inst) || isa<CallInst>(Inst)) &&
120 isa<Function>(Inst.getOperand(0)))
121 ++OI; // Skip actual functions for direct function calls.
122 for (; OI != Inst.op_end(); ++OI)
123 if (isa<PointerType>((*OI)->getType()) && !isa<ConstantPointerNull>(*OI))
124 Pointers.insert(*OI);
126 CallSite CS = CallSite::get(&*I);
127 if (CS.getInstruction()) CallSites.insert(CS);
130 if (PrintNoAlias || PrintMayAlias || PrintMustAlias ||
131 PrintNoModRef || PrintMod || PrintRef || PrintModRef)
132 cerr << "Function: " << F.getName() << ": " << Pointers.size()
133 << " pointers, " << CallSites.size() << " call sites\n";
135 // iterate over the worklist, and run the full (n^2)/2 disambiguations
136 for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
139 const Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
140 if (I1ElTy->isSized()) I1Size = TD.getTypeSize(I1ElTy);
142 for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
144 const Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
145 if (I2ElTy->isSized()) I2Size = TD.getTypeSize(I2ElTy);
147 switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
148 case AliasAnalysis::NoAlias:
149 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
151 case AliasAnalysis::MayAlias:
152 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
154 case AliasAnalysis::MustAlias:
155 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
158 cerr << "Unknown alias query result!\n";
163 // Mod/ref alias analysis: compare all pairs of calls and values
164 for (std::set<CallSite>::iterator C = CallSites.begin(),
165 Ce = CallSites.end(); C != Ce; ++C) {
166 Instruction *I = C->getInstruction();
168 for (std::set<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
171 const Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
172 if (ElTy->isSized()) Size = TD.getTypeSize(ElTy);
174 switch (AA.getModRefInfo(*C, *V, Size)) {
175 case AliasAnalysis::NoModRef:
176 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
178 case AliasAnalysis::Mod:
179 PrintModRefResults(" Mod", PrintMod, I, *V, F.getParent());
181 case AliasAnalysis::Ref:
182 PrintModRefResults(" Ref", PrintRef, I, *V, F.getParent());
184 case AliasAnalysis::ModRef:
185 PrintModRefResults(" ModRef", PrintModRef, I, *V, F.getParent());
188 cerr << "Unknown alias query result!\n";
196 static void PrintPercent(unsigned Num, unsigned Sum) {
197 cerr << "(" << Num*100ULL/Sum << "."
198 << ((Num*1000ULL/Sum) % 10) << "%)\n";
201 bool AAEval::doFinalization(Module &M) {
202 unsigned AliasSum = NoAlias + MayAlias + MustAlias;
203 cerr << "===== Alias Analysis Evaluator Report =====\n";
205 cerr << " Alias Analysis Evaluator Summary: No pointers!\n";
207 cerr << " " << AliasSum << " Total Alias Queries Performed\n";
208 cerr << " " << NoAlias << " no alias responses ";
209 PrintPercent(NoAlias, AliasSum);
210 cerr << " " << MayAlias << " may alias responses ";
211 PrintPercent(MayAlias, AliasSum);
212 cerr << " " << MustAlias << " must alias responses ";
213 PrintPercent(MustAlias, AliasSum);
214 cerr << " Alias Analysis Evaluator Pointer Alias Summary: "
215 << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
216 << MustAlias*100/AliasSum << "%\n";
219 // Display the summary for mod/ref analysis
220 unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
221 if (ModRefSum == 0) {
222 cerr << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
224 cerr << " " << ModRefSum << " Total ModRef Queries Performed\n";
225 cerr << " " << NoModRef << " no mod/ref responses ";
226 PrintPercent(NoModRef, ModRefSum);
227 cerr << " " << Mod << " mod responses ";
228 PrintPercent(Mod, ModRefSum);
229 cerr << " " << Ref << " ref responses ";
230 PrintPercent(Ref, ModRefSum);
231 cerr << " " << ModRef << " mod & ref responses ";
232 PrintPercent(ModRef, ModRefSum);
233 cerr << " Alias Analysis Evaluator Mod/Ref Summary: "
234 << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
235 << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";