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/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 static RegisterPass<AAEval>
78 X("aa-eval", "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 bool AAEval::runOnFunction(Function &F) {
111 AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
113 SetVector<Value *> Pointers;
114 SetVector<CallSite> CallSites;
116 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
117 if (isa<PointerType>(I->getType())) // Add all pointer arguments
120 for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
121 if (isa<PointerType>(I->getType())) // Add all pointer instructions
122 Pointers.insert(&*I);
123 Instruction &Inst = *I;
124 User::op_iterator OI = Inst.op_begin();
125 CallSite CS = CallSite::get(&Inst);
126 if (CS.getInstruction() &&
127 isa<Function>(CS.getCalledValue()))
128 ++OI; // Skip actual functions for direct function calls.
129 for (; OI != Inst.op_end(); ++OI)
130 if (isa<PointerType>((*OI)->getType()) && !isa<ConstantPointerNull>(*OI))
131 Pointers.insert(*OI);
133 if (CS.getInstruction()) CallSites.insert(CS);
136 if (PrintNoAlias || PrintMayAlias || PrintMustAlias ||
137 PrintNoModRef || PrintMod || PrintRef || PrintModRef)
138 errs() << "Function: " << F.getName() << ": " << Pointers.size()
139 << " pointers, " << CallSites.size() << " call sites\n";
141 // iterate over the worklist, and run the full (n^2)/2 disambiguations
142 for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
144 unsigned I1Size = ~0u;
145 const Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
146 if (I1ElTy->isSized()) I1Size = AA.getTypeStoreSize(I1ElTy);
148 for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
149 unsigned I2Size = ~0u;
150 const Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
151 if (I2ElTy->isSized()) I2Size = AA.getTypeStoreSize(I2ElTy);
153 switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
154 case AliasAnalysis::NoAlias:
155 PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
157 case AliasAnalysis::MayAlias:
158 PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
160 case AliasAnalysis::MustAlias:
161 PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
164 errs() << "Unknown alias query result!\n";
169 // Mod/ref alias analysis: compare all pairs of calls and values
170 for (SetVector<CallSite>::iterator C = CallSites.begin(),
171 Ce = CallSites.end(); C != Ce; ++C) {
172 Instruction *I = C->getInstruction();
174 for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
177 const Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
178 if (ElTy->isSized()) Size = AA.getTypeStoreSize(ElTy);
180 switch (AA.getModRefInfo(*C, *V, Size)) {
181 case AliasAnalysis::NoModRef:
182 PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
184 case AliasAnalysis::Mod:
185 PrintModRefResults(" Mod", PrintMod, I, *V, F.getParent());
187 case AliasAnalysis::Ref:
188 PrintModRefResults(" Ref", PrintRef, I, *V, F.getParent());
190 case AliasAnalysis::ModRef:
191 PrintModRefResults(" ModRef", PrintModRef, I, *V, F.getParent());
194 errs() << "Unknown alias query result!\n";
202 static void PrintPercent(unsigned Num, unsigned Sum) {
203 errs() << "(" << Num*100ULL/Sum << "."
204 << ((Num*1000ULL/Sum) % 10) << "%)\n";
207 bool AAEval::doFinalization(Module &M) {
208 unsigned AliasSum = NoAlias + MayAlias + MustAlias;
209 errs() << "===== Alias Analysis Evaluator Report =====\n";
211 errs() << " Alias Analysis Evaluator Summary: No pointers!\n";
213 errs() << " " << AliasSum << " Total Alias Queries Performed\n";
214 errs() << " " << NoAlias << " no alias responses ";
215 PrintPercent(NoAlias, AliasSum);
216 errs() << " " << MayAlias << " may alias responses ";
217 PrintPercent(MayAlias, AliasSum);
218 errs() << " " << MustAlias << " must alias responses ";
219 PrintPercent(MustAlias, AliasSum);
220 errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
221 << NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
222 << MustAlias*100/AliasSum << "%\n";
225 // Display the summary for mod/ref analysis
226 unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
227 if (ModRefSum == 0) {
228 errs() << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
230 errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
231 errs() << " " << NoModRef << " no mod/ref responses ";
232 PrintPercent(NoModRef, ModRefSum);
233 errs() << " " << Mod << " mod responses ";
234 PrintPercent(Mod, ModRefSum);
235 errs() << " " << Ref << " ref responses ";
236 PrintPercent(Ref, ModRefSum);
237 errs() << " " << ModRef << " mod & ref responses ";
238 PrintPercent(ModRef, ModRefSum);
239 errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
240 << NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
241 << Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";