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/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"
38 cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
40 cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
41 cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
42 cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
44 cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
45 cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
46 cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
47 cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
49 class VISIBILITY_HIDDEN AAEval : public FunctionPass {
50 unsigned NoAlias, MayAlias, MustAlias;
51 unsigned NoModRef, Mod, Ref, ModRef;
54 static char ID; // Pass identification, replacement for typeid
55 AAEval() : FunctionPass((intptr_t)&ID) {}
57 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
58 AU.addRequired<AliasAnalysis>();
62 bool doInitialization(Module &M) {
63 NoAlias = MayAlias = MustAlias = 0;
64 NoModRef = Mod = Ref = ModRef = 0;
67 PrintNoAlias = PrintMayAlias = PrintMustAlias = true;
68 PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
73 /// isAnalysis - Return true if this pass is implementing an analysis pass.
74 virtual bool isAnalysis() const { return true; }
76 bool runOnFunction(Function &F);
77 bool doFinalization(Module &M);
82 X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator");
85 FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }
87 static void PrintResults(const char *Msg, bool P, const Value *V1, const Value *V2,
90 std::stringstream s1, s2;
91 WriteAsOperand(s1, V1, true, M);
92 WriteAsOperand(s2, V2, true, M);
93 std::string o1(s1.str()), o2(s2.str());
96 cerr << " " << Msg << ":\t"
103 PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
106 cerr << " " << Msg << ": Ptr: ";
107 WriteAsOperand(*cerr.stream(), Ptr, true, M);
108 cerr << "\t<->" << *I;
112 bool AAEval::runOnFunction(Function &F) {
113 AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
115 const TargetData &TD = AA.getTargetData();
117 std::set<Value *> Pointers;
118 std::set<CallSite> CallSites;
120 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
121 if (isa<PointerType>(I->getType())) // Add all pointer arguments
124 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
125 if (isa<PointerType>(I->getType())) // Add all pointer instructions
126 Pointers.insert(&*I);
127 Instruction &Inst = *I;
128 User::op_iterator OI = Inst.op_begin();
129 if ((isa<InvokeInst>(Inst) || isa<CallInst>(Inst)) &&
130 isa<Function>(Inst.getOperand(0)))
131 ++OI; // Skip actual functions for direct function calls.
132 for (; OI != Inst.op_end(); ++OI)
133 if (isa<PointerType>((*OI)->getType()) && !isa<ConstantPointerNull>(*OI))
134 Pointers.insert(*OI);
136 CallSite CS = CallSite::get(&*I);
137 if (CS.getInstruction()) CallSites.insert(CS);
140 if (PrintNoAlias || PrintMayAlias || PrintMustAlias ||
141 PrintNoModRef || PrintMod || PrintRef || PrintModRef)
142 cerr << "Function: " << F.getName() << ": " << Pointers.size()
143 << " pointers, " << CallSites.size() << " call sites\n";
145 // iterate over the worklist, and run the full (n^2)/2 disambiguations
146 for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
149 const Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
150 if (I1ElTy->isSized()) I1Size = TD.getTypeStoreSize(I1ElTy);
152 for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
154 const Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
155 if (I2ElTy->isSized()) I2Size = TD.getTypeStoreSize(I2ElTy);
157 switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
158 case AliasAnalysis::NoAlias:
159 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
161 case AliasAnalysis::MayAlias:
162 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
164 case AliasAnalysis::MustAlias:
165 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
168 cerr << "Unknown alias query result!\n";
173 // Mod/ref alias analysis: compare all pairs of calls and values
174 for (std::set<CallSite>::iterator C = CallSites.begin(),
175 Ce = CallSites.end(); C != Ce; ++C) {
176 Instruction *I = C->getInstruction();
178 for (std::set<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
181 const Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
182 if (ElTy->isSized()) Size = TD.getTypeStoreSize(ElTy);
184 switch (AA.getModRefInfo(*C, *V, Size)) {
185 case AliasAnalysis::NoModRef:
186 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
188 case AliasAnalysis::Mod:
189 PrintModRefResults(" Mod", PrintMod, I, *V, F.getParent());
191 case AliasAnalysis::Ref:
192 PrintModRefResults(" Ref", PrintRef, I, *V, F.getParent());
194 case AliasAnalysis::ModRef:
195 PrintModRefResults(" ModRef", PrintModRef, I, *V, F.getParent());
198 cerr << "Unknown alias query result!\n";
206 static void PrintPercent(unsigned Num, unsigned Sum) {
207 cerr << "(" << Num*100ULL/Sum << "."
208 << ((Num*1000ULL/Sum) % 10) << "%)\n";
211 bool AAEval::doFinalization(Module &M) {
212 unsigned AliasSum = NoAlias + MayAlias + MustAlias;
213 cerr << "===== Alias Analysis Evaluator Report =====\n";
215 cerr << " Alias Analysis Evaluator Summary: No pointers!\n";
217 cerr << " " << AliasSum << " Total Alias Queries Performed\n";
218 cerr << " " << NoAlias << " no alias responses ";
219 PrintPercent(NoAlias, AliasSum);
220 cerr << " " << MayAlias << " may alias responses ";
221 PrintPercent(MayAlias, AliasSum);
222 cerr << " " << MustAlias << " must alias responses ";
223 PrintPercent(MustAlias, AliasSum);
224 cerr << " Alias Analysis Evaluator Pointer Alias Summary: "
225 << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
226 << MustAlias*100/AliasSum << "%\n";
229 // Display the summary for mod/ref analysis
230 unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
231 if (ModRefSum == 0) {
232 cerr << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
234 cerr << " " << ModRefSum << " Total ModRef Queries Performed\n";
235 cerr << " " << NoModRef << " no mod/ref responses ";
236 PrintPercent(NoModRef, ModRefSum);
237 cerr << " " << Mod << " mod responses ";
238 PrintPercent(Mod, ModRefSum);
239 cerr << " " << Ref << " ref responses ";
240 PrintPercent(Ref, ModRefSum);
241 cerr << " " << ModRef << " mod & ref responses ";
242 PrintPercent(ModRef, ModRefSum);
243 cerr << " Alias Analysis Evaluator Mod/Ref Summary: "
244 << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
245 << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";