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llvm-project/llvm/lib/Analysis/AliasAnalysisEvaluator.cpp

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//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// 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/Passes.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
static cl::opt<bool> PrintAll("print-all-alias-modref-info", cl::ReallyHidden);
static cl::opt<bool> PrintNoAlias("print-no-aliases", cl::ReallyHidden);
static cl::opt<bool> PrintMayAlias("print-may-aliases", cl::ReallyHidden);
static cl::opt<bool> PrintPartialAlias("print-partial-aliases", cl::ReallyHidden);
static cl::opt<bool> PrintMustAlias("print-must-aliases", cl::ReallyHidden);
static cl::opt<bool> PrintNoModRef("print-no-modref", cl::ReallyHidden);
static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
static cl::opt<bool> PrintRef("print-ref", cl::ReallyHidden);
static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
static cl::opt<bool> EvalTBAA("evaluate-tbaa", cl::ReallyHidden);
namespace {
class AAEval : public FunctionPass {
unsigned NoAlias, MayAlias, PartialAlias, MustAlias;
unsigned NoModRef, Mod, Ref, ModRef;
public:
static char ID; // Pass identification, replacement for typeid
AAEval() : FunctionPass(ID) {
initializeAAEvalPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AliasAnalysis>();
AU.setPreservesAll();
}
bool doInitialization(Module &M) override {
NoAlias = MayAlias = PartialAlias = MustAlias = 0;
NoModRef = Mod = Ref = ModRef = 0;
if (PrintAll) {
PrintNoAlias = PrintMayAlias = true;
PrintPartialAlias = PrintMustAlias = true;
PrintNoModRef = PrintMod = PrintRef = PrintModRef = true;
}
return false;
}
bool runOnFunction(Function &F) override;
bool doFinalization(Module &M) override;
};
}
char AAEval::ID = 0;
INITIALIZE_PASS_BEGIN(AAEval, "aa-eval",
"Exhaustive Alias Analysis Precision Evaluator", false, true)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_END(AAEval, "aa-eval",
"Exhaustive Alias Analysis Precision Evaluator", false, true)
FunctionPass *llvm::createAAEvalPass() { return new AAEval(); }
static void PrintResults(const char *Msg, bool P, const Value *V1,
const Value *V2, const Module *M) {
if (P) {
std::string o1, o2;
{
raw_string_ostream os1(o1), os2(o2);
V1->printAsOperand(os1, true, M);
V2->printAsOperand(os2, true, M);
}
if (o2 < o1)
std::swap(o1, o2);
errs() << " " << Msg << ":\t"
<< o1 << ", "
<< o2 << "\n";
}
}
static inline void
PrintModRefResults(const char *Msg, bool P, Instruction *I, Value *Ptr,
Module *M) {
if (P) {
errs() << " " << Msg << ": Ptr: ";
Ptr->printAsOperand(errs(), true, M);
errs() << "\t<->" << *I << '\n';
}
}
static inline void
PrintModRefResults(const char *Msg, bool P, CallSite CSA, CallSite CSB,
Module *M) {
if (P) {
errs() << " " << Msg << ": " << *CSA.getInstruction()
<< " <-> " << *CSB.getInstruction() << '\n';
}
}
static inline void
PrintLoadStoreResults(const char *Msg, bool P, const Value *V1,
const Value *V2, const Module *M) {
if (P) {
errs() << " " << Msg << ": " << *V1
<< " <-> " << *V2 << '\n';
}
}
static inline bool isInterestingPointer(Value *V) {
return V->getType()->isPointerTy()
&& !isa<ConstantPointerNull>(V);
}
bool AAEval::runOnFunction(Function &F) {
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
SetVector<Value *> Pointers;
SetVector<CallSite> CallSites;
SetVector<Value *> Loads;
SetVector<Value *> Stores;
for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
if (I->getType()->isPointerTy()) // Add all pointer arguments.
Pointers.insert(I);
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
if (I->getType()->isPointerTy()) // Add all pointer instructions.
Pointers.insert(&*I);
if (EvalTBAA && isa<LoadInst>(&*I))
Loads.insert(&*I);
if (EvalTBAA && isa<StoreInst>(&*I))
Stores.insert(&*I);
Instruction &Inst = *I;
if (CallSite CS = cast<Value>(&Inst)) {
Value *Callee = CS.getCalledValue();
// Skip actual functions for direct function calls.
if (!isa<Function>(Callee) && isInterestingPointer(Callee))
Pointers.insert(Callee);
// Consider formals.
for (CallSite::arg_iterator AI = CS.arg_begin(), AE = CS.arg_end();
AI != AE; ++AI)
if (isInterestingPointer(*AI))
Pointers.insert(*AI);
CallSites.insert(CS);
} else {
// Consider all operands.
for (Instruction::op_iterator OI = Inst.op_begin(), OE = Inst.op_end();
OI != OE; ++OI)
if (isInterestingPointer(*OI))
Pointers.insert(*OI);
}
}
if (PrintNoAlias || PrintMayAlias || PrintPartialAlias || PrintMustAlias ||
PrintNoModRef || PrintMod || PrintRef || PrintModRef)
errs() << "Function: " << F.getName() << ": " << Pointers.size()
<< " pointers, " << CallSites.size() << " call sites\n";
// iterate over the worklist, and run the full (n^2)/2 disambiguations
for (SetVector<Value *>::iterator I1 = Pointers.begin(), E = Pointers.end();
I1 != E; ++I1) {
uint64_t I1Size = AliasAnalysis::UnknownSize;
Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
if (I1ElTy->isSized()) I1Size = AA.getTypeStoreSize(I1ElTy);
for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
uint64_t I2Size = AliasAnalysis::UnknownSize;
Type *I2ElTy =cast<PointerType>((*I2)->getType())->getElementType();
if (I2ElTy->isSized()) I2Size = AA.getTypeStoreSize(I2ElTy);
switch (AA.alias(*I1, I1Size, *I2, I2Size)) {
case AliasAnalysis::NoAlias:
PrintResults("NoAlias", PrintNoAlias, *I1, *I2, F.getParent());
++NoAlias; break;
case AliasAnalysis::MayAlias:
PrintResults("MayAlias", PrintMayAlias, *I1, *I2, F.getParent());
++MayAlias; break;
case AliasAnalysis::PartialAlias:
PrintResults("PartialAlias", PrintPartialAlias, *I1, *I2,
F.getParent());
++PartialAlias; break;
case AliasAnalysis::MustAlias:
PrintResults("MustAlias", PrintMustAlias, *I1, *I2, F.getParent());
++MustAlias; break;
}
}
}
if (EvalTBAA) {
// iterate over all pairs of load, store
for (SetVector<Value *>::iterator I1 = Loads.begin(), E = Loads.end();
I1 != E; ++I1) {
for (SetVector<Value *>::iterator I2 = Stores.begin(), E2 = Stores.end();
I2 != E2; ++I2) {
switch (AA.alias(AA.getLocation(cast<LoadInst>(*I1)),
AA.getLocation(cast<StoreInst>(*I2)))) {
case AliasAnalysis::NoAlias:
PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
F.getParent());
++NoAlias; break;
case AliasAnalysis::MayAlias:
PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
F.getParent());
++MayAlias; break;
case AliasAnalysis::PartialAlias:
PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
F.getParent());
++PartialAlias; break;
case AliasAnalysis::MustAlias:
PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
F.getParent());
++MustAlias; break;
}
}
}
// iterate over all pairs of store, store
for (SetVector<Value *>::iterator I1 = Stores.begin(), E = Stores.end();
I1 != E; ++I1) {
for (SetVector<Value *>::iterator I2 = Stores.begin(); I2 != I1; ++I2) {
switch (AA.alias(AA.getLocation(cast<StoreInst>(*I1)),
AA.getLocation(cast<StoreInst>(*I2)))) {
case AliasAnalysis::NoAlias:
PrintLoadStoreResults("NoAlias", PrintNoAlias, *I1, *I2,
F.getParent());
++NoAlias; break;
case AliasAnalysis::MayAlias:
PrintLoadStoreResults("MayAlias", PrintMayAlias, *I1, *I2,
F.getParent());
++MayAlias; break;
case AliasAnalysis::PartialAlias:
PrintLoadStoreResults("PartialAlias", PrintPartialAlias, *I1, *I2,
F.getParent());
++PartialAlias; break;
case AliasAnalysis::MustAlias:
PrintLoadStoreResults("MustAlias", PrintMustAlias, *I1, *I2,
F.getParent());
++MustAlias; break;
}
}
}
}
// Mod/ref alias analysis: compare all pairs of calls and values
for (SetVector<CallSite>::iterator C = CallSites.begin(),
Ce = CallSites.end(); C != Ce; ++C) {
Instruction *I = C->getInstruction();
for (SetVector<Value *>::iterator V = Pointers.begin(), Ve = Pointers.end();
V != Ve; ++V) {
uint64_t Size = AliasAnalysis::UnknownSize;
Type *ElTy = cast<PointerType>((*V)->getType())->getElementType();
if (ElTy->isSized()) Size = AA.getTypeStoreSize(ElTy);
switch (AA.getModRefInfo(*C, *V, Size)) {
case AliasAnalysis::NoModRef:
PrintModRefResults("NoModRef", PrintNoModRef, I, *V, F.getParent());
++NoModRef; break;
case AliasAnalysis::Mod:
PrintModRefResults("Just Mod", PrintMod, I, *V, F.getParent());
++Mod; break;
case AliasAnalysis::Ref:
PrintModRefResults("Just Ref", PrintRef, I, *V, F.getParent());
++Ref; break;
case AliasAnalysis::ModRef:
PrintModRefResults("Both ModRef", PrintModRef, I, *V, F.getParent());
++ModRef; break;
}
}
}
// Mod/ref alias analysis: compare all pairs of calls
for (SetVector<CallSite>::iterator C = CallSites.begin(),
Ce = CallSites.end(); C != Ce; ++C) {
for (SetVector<CallSite>::iterator D = CallSites.begin(); D != Ce; ++D) {
if (D == C)
continue;
switch (AA.getModRefInfo(*C, *D)) {
case AliasAnalysis::NoModRef:
PrintModRefResults("NoModRef", PrintNoModRef, *C, *D, F.getParent());
++NoModRef; break;
case AliasAnalysis::Mod:
PrintModRefResults("Just Mod", PrintMod, *C, *D, F.getParent());
++Mod; break;
case AliasAnalysis::Ref:
PrintModRefResults("Just Ref", PrintRef, *C, *D, F.getParent());
++Ref; break;
case AliasAnalysis::ModRef:
PrintModRefResults("Both ModRef", PrintModRef, *C, *D, F.getParent());
++ModRef; break;
}
}
}
return false;
}
static void PrintPercent(unsigned Num, unsigned Sum) {
errs() << "(" << Num*100ULL/Sum << "."
<< ((Num*1000ULL/Sum) % 10) << "%)\n";
}
bool AAEval::doFinalization(Module &M) {
unsigned AliasSum = NoAlias + MayAlias + PartialAlias + MustAlias;
errs() << "===== Alias Analysis Evaluator Report =====\n";
if (AliasSum == 0) {
errs() << " Alias Analysis Evaluator Summary: No pointers!\n";
} else {
errs() << " " << AliasSum << " Total Alias Queries Performed\n";
errs() << " " << NoAlias << " no alias responses ";
PrintPercent(NoAlias, AliasSum);
errs() << " " << MayAlias << " may alias responses ";
PrintPercent(MayAlias, AliasSum);
errs() << " " << PartialAlias << " partial alias responses ";
PrintPercent(PartialAlias, AliasSum);
errs() << " " << MustAlias << " must alias responses ";
PrintPercent(MustAlias, AliasSum);
errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
<< NoAlias*100/AliasSum << "%/" << MayAlias*100/AliasSum << "%/"
<< PartialAlias*100/AliasSum << "%/"
<< MustAlias*100/AliasSum << "%\n";
}
// Display the summary for mod/ref analysis
unsigned ModRefSum = NoModRef + Mod + Ref + ModRef;
if (ModRefSum == 0) {
errs() << " Alias Analysis Mod/Ref Evaluator Summary: no mod/ref!\n";
} else {
errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
errs() << " " << NoModRef << " no mod/ref responses ";
PrintPercent(NoModRef, ModRefSum);
errs() << " " << Mod << " mod responses ";
PrintPercent(Mod, ModRefSum);
errs() << " " << Ref << " ref responses ";
PrintPercent(Ref, ModRefSum);
errs() << " " << ModRef << " mod & ref responses ";
PrintPercent(ModRef, ModRefSum);
errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
<< NoModRef*100/ModRefSum << "%/" << Mod*100/ModRefSum << "%/"
<< Ref*100/ModRefSum << "%/" << ModRef*100/ModRefSum << "%\n";
}
return false;
}
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