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/Function.h"
21 #include "llvm/Instructions.h"
22 #include "llvm/Pass.h"
23 #include "llvm/DerivedTypes.h"
24 #include "llvm/Analysis/AliasAnalysis.h"
25 #include "llvm/Assembly/Writer.h"
26 #include "llvm/Support/InstIterator.h"
27 #include "llvm/Support/CommandLine.h"
34 cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
36 cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
37 cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
38 cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
40 cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
41 cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
42 cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
43 cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
45 class AAEval : public FunctionPass {
46 unsigned NoAlias, MayAlias, MustAlias;
47 unsigned NoModRef, Mod, Ref, ModRef;
50 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
51 AU.addRequired<AliasAnalysis>();
55 bool doInitialization(Module &M) {
56 NoAlias = MayAlias = MustAlias = 0;
57 NoModRef = Mod = Ref = ModRef = 0;
60 PrintNoAlias = PrintMayAlias = PrintMustAlias = true;
61 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
66 bool runOnFunction(Function &F);
67 bool doFinalization(Module &M);
71 X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator");
74 static inline void PrintResults(const char *Msg, bool P, Value *V1, Value *V2,
77 std::cerr << " " << Msg << ":\t";
78 WriteAsOperand(std::cerr, V1, true, true, M) << ", ";
79 WriteAsOperand(std::cerr, V2, true, true, M) << "\n";
84 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
87 std::cerr << " " << Msg << ": Ptr: ";
88 WriteAsOperand(std::cerr, Ptr, true, true, M);
89 std::cerr << "\t<->" << *I;
93 bool AAEval::runOnFunction(Function &F) {
94 AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
96 std::set<Value *> Pointers;
97 std::set<CallSite> CallSites;
99 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
100 if (isa<PointerType>(I->getType())) // Add all pointer arguments
103 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
104 if (isa<PointerType>(I->getType())) // Add all pointer instructions
105 Pointers.insert(&*I);
106 for (User::op_iterator OI = (*I).op_begin(); OI != (*I).op_end(); ++OI)
107 if (isa<PointerType>((*OI)->getType()))
108 Pointers.insert(*OI);
110 CallSite CS = CallSite::get(&*I);
111 if (CS.getInstruction()) CallSites.insert(CS);
114 if (PrintNoAlias || PrintMayAlias || PrintMustAlias ||
115 PrintNoModRef || PrintMod || PrintRef || PrintModRef)
116 std::cerr << "Function: " << F.getName() << ": " << Pointers.size()
117 << " pointers, " << CallSites.size() << " call sites\n";
119 // iterate over the worklist, and run the full (n^2)/2 disambiguations
120 for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
122 for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2)
123 switch (AA.alias(*I1, 0, *I2, 0)) {
124 case AliasAnalysis::NoAlias:
125 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
127 case AliasAnalysis::MayAlias:
128 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
130 case AliasAnalysis::MustAlias:
131 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
134 std::cerr << "Unknown alias query result!\n";
137 // Mod/ref alias analysis: compare all pairs of calls and values
138 for (std::set<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
141 if (const PointerType *PTy = dyn_cast<PointerType>((*V)->getType()))
142 if (!(Size = PTy->getElementType()->getPrimitiveSize()))
143 if (isa<PointerType>(PTy->getElementType()))
144 Size = 4; // This is a hack, but it's good enough for eval.
147 for (std::set<CallSite>::iterator C = CallSites.begin(),
148 Ce = CallSites.end(); C != Ce; ++C) {
149 Instruction *I = C->getInstruction();
150 switch (AA.getModRefInfo(*C, *V, Size)) {
151 case AliasAnalysis::NoModRef:
152 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
154 case AliasAnalysis::Mod:
155 PrintModRefResults(" Mod", PrintMod, I, *V, F.getParent());
157 case AliasAnalysis::Ref:
158 PrintModRefResults(" Ref", PrintRef, I, *V, F.getParent());
160 case AliasAnalysis::ModRef:
161 PrintModRefResults(" ModRef", PrintModRef, I, *V, F.getParent());
164 std::cerr << "Unknown alias query result!\n";
172 bool AAEval::doFinalization(Module &M) {
173 unsigned AliasSum = NoAlias + MayAlias + MustAlias;
174 std::cerr << "===== Alias Analysis Evaluator Report =====\n";
176 std::cerr << " Alias Analysis Evaluator Summary: No pointers!\n";
178 std::cerr << " " << AliasSum << " Total Alias Queries Performed\n";
179 std::cerr << " " << NoAlias << " no alias responses ("
180 << NoAlias*100/AliasSum << "%)\n";
181 std::cerr << " " << MayAlias << " may alias responses ("
182 << MayAlias*100/AliasSum << "%)\n";
183 std::cerr << " " << MustAlias << " must alias responses ("
184 << MustAlias*100/AliasSum <<"%)\n";
185 std::cerr << " Alias Analysis Evaluator Pointer Alias Summary: "
186 << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
187 << MustAlias*100/AliasSum << "%\n";
190 // Display the summary for mod/ref analysis
191 unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
192 if (ModRefSum == 0) {
193 std::cerr << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
195 std::cerr << " " << ModRefSum << " Total ModRef Queries Performed\n";
196 std::cerr << " " << NoModRef << " no mod/ref responses ("
197 << NoModRef*100/ModRefSum << "%)\n";
198 std::cerr << " " << Mod << " mod responses ("
199 << Mod*100/ModRefSum << "%)\n";
200 std::cerr << " " << Ref << " ref responses ("
201 << Ref*100/ModRefSum <<"%)\n";
202 std::cerr << " " << ModRef << " mod & ref responses ("
203 << ModRef*100/ModRefSum <<"%)\n";
204 std::cerr << " Alias Analysis Evaluator Mod/Ref Summary: "
205 << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
206 << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";