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//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
//
// This file implements a simple N^2 alias analysis accuracy evaluator.
// Basically, for each function in the program, it simply queries to see how the
// alias analysis implementation answers alias queries between each pair of
// pointers in the function.
//
// This is inspired and adapted from code by: Naveen Neelakantam, Francesco
// Spadini, and Wojciech Stryjewski.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Pass.h"
#include "llvm/Function.h"
#include "llvm/Type.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Assembly/Writer.h"
#include "Support/CommandLine.h"
#include <set>
namespace {
cl::opt<bool> PrintNo ("print-no-aliases", cl::ReallyHidden);
cl::opt<bool> PrintMay ("print-may-aliases", cl::ReallyHidden);
cl::opt<bool> PrintMust("print-must-aliases", cl::ReallyHidden);
class AAEval : public FunctionPass {
unsigned No, May, Must;
public:
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<AliasAnalysis>();
AU.setPreservesAll();
}
bool doInitialization(Module &M) { No = May = Must = 0; return false; }
bool runOnFunction(Function &F);
bool doFinalization(Module &M);
};
RegisterOpt<AAEval>
X("aa-eval", "Exhaustive Alias Analysis Precision Evaluator");
}
static inline void PrintResults(const char *Msg, bool P, Value *V1, Value *V2) {
if (P) {
std::cerr << " " << Msg << ":\t";
WriteAsOperand(std::cerr, V1) << ", ";
WriteAsOperand(std::cerr, V2) << "\n";
}
}
bool AAEval::runOnFunction(Function &F) {
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
std::set<Value *> Pointers;
for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
if (isa<PointerType>(I->getType())) // Add all pointer arguments
Pointers.insert(I);
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
if (isa<PointerType>((*I)->getType())) // Add all pointer instructions
Pointers.insert(*I);
for (User::op_iterator OI = (*I)->op_begin(); OI != (*I)->op_end(); ++OI)
if (isa<PointerType>((*OI)->getType()))
Pointers.insert(*OI);
}
if (PrintNo || PrintMay || PrintMust)
std::cerr << "Function: " << F.getName() << "\n";
// iterate over the worklist, and run the full (n^2)/2 disambiguations
for (std::set<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
I1 != E; ++I1)
for (std::set<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2)
switch (AA.alias(*I1, 0, *I2, 0)) {
case AliasAnalysis::NoAlias:
PrintResults("No", PrintNo, *I1, *I2);
++No; break;
case AliasAnalysis::MayAlias:
PrintResults("May", PrintMay, *I1, *I2);
++May; break;
case AliasAnalysis::MustAlias:
PrintResults("Must", PrintMust, *I1, *I2);
++Must; break;
default:
std::cerr << "Unknown alias query result!\n";
}
return false;
}
bool AAEval::doFinalization(Module &M) {
unsigned Sum = No+May+Must;
std::cerr << "===== Alias Analysis Evaluator Report =====\n";
if (Sum == 0) {
std::cerr << " Alias Analysis Evaluator Summary: No pointers!\n";
return false;
}
std::cerr << " " << Sum << " Total Alias Queries Performed\n";
std::cerr << " " << No << " no alias responses (" << No*100/Sum << "%)\n";
std::cerr << " " << May << " may alias responses (" << May*100/Sum << "%)\n";
std::cerr << " " << Must << " must alias responses (" <<Must*100/Sum<<"%)\n";
std::cerr << " Alias Analysis Evaluator Summary: " << No*100/Sum << "%/"
<< May*100/Sum << "%/" << Must*100/Sum<<"%\n";
return false;
}
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