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

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//===- AliasAnalysisEvaluator.cpp - Alias Analysis Accuracy Evaluator -----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysisEvaluator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.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> PrintRef("print-ref", cl::ReallyHidden);
static cl::opt<bool> PrintMod("print-mod", cl::ReallyHidden);
static cl::opt<bool> PrintModRef("print-modref", cl::ReallyHidden);
static cl::opt<bool> PrintMust("print-must", cl::ReallyHidden);
static cl::opt<bool> PrintMustRef("print-mustref", cl::ReallyHidden);
static cl::opt<bool> PrintMustMod("print-mustmod", cl::ReallyHidden);
static cl::opt<bool> PrintMustModRef("print-mustmodref", cl::ReallyHidden);
static cl::opt<bool> EvalAAMD("evaluate-aa-metadata", cl::ReallyHidden);
static void PrintResults(AliasResult AR, bool P, const Value *V1,
const Value *V2, const Module *M) {
if (PrintAll || 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() << " " << AR << ":\t" << o1 << ", " << o2 << "\n";
}
}
static inline void PrintModRefResults(const char *Msg, bool P, Instruction *I,
Value *Ptr, Module *M) {
if (PrintAll || P) {
errs() << " " << Msg << ": Ptr: ";
Ptr->printAsOperand(errs(), true, M);
errs() << "\t<->" << *I << '\n';
}
}
static inline void PrintModRefResults(const char *Msg, bool P, CallBase *CallA,
CallBase *CallB, Module *M) {
if (PrintAll || P) {
errs() << " " << Msg << ": " << *CallA << " <-> " << *CallB << '\n';
}
}
static inline void PrintLoadStoreResults(AliasResult AR, bool P,
const Value *V1, const Value *V2,
const Module *M) {
if (PrintAll || P) {
errs() << " " << AR << ": " << *V1 << " <-> " << *V2 << '\n';
}
}
static inline bool isInterestingPointer(Value *V) {
return V->getType()->isPointerTy()
&& !isa<ConstantPointerNull>(V);
}
PreservedAnalyses AAEvaluator::run(Function &F, FunctionAnalysisManager &AM) {
runInternal(F, AM.getResult<AAManager>(F));
return PreservedAnalyses::all();
}
void AAEvaluator::runInternal(Function &F, AAResults &AA) {
const DataLayout &DL = F.getParent()->getDataLayout();
++FunctionCount;
SetVector<Value *> Pointers;
SmallSetVector<CallBase *, 16> Calls;
SetVector<Value *> Loads;
SetVector<Value *> Stores;
Analysis: Remove implicit ilist iterator conversions Remove implicit ilist iterator conversions from LLVMAnalysis. I came across something really scary in `llvm::isKnownNotFullPoison()` which relied on `Instruction::getNextNode()` being completely broken (not surprising, but scary nevertheless). This function is documented (and coded to) return `nullptr` when it gets to the sentinel, but with an `ilist_half_node` as a sentinel, the sentinel check looks into some other memory and we don't recognize we've hit the end. Rooting out these scary cases is the reason I'm removing the implicit conversions before doing anything else with `ilist`; I'm not at all surprised that clients rely on badness. I found another scary case -- this time, not relying on badness, just bad (but I guess getting lucky so far) -- in `ObjectSizeOffsetEvaluator::compute_()`. Here, we save out the insertion point, do some things, and then restore it. Previously, we let the iterator auto-convert to `Instruction*`, and then set it back using the `Instruction*` version: Instruction *PrevInsertPoint = Builder.GetInsertPoint(); /* Logic that may change insert point */ if (PrevInsertPoint) Builder.SetInsertPoint(PrevInsertPoint); The check for `PrevInsertPoint` doesn't protect correctly against bad accesses. If the insertion point has been set to the end of a basic block (i.e., `SetInsertPoint(SomeBB)`), then `GetInsertPoint()` returns an iterator pointing at the list sentinel. The version of `SetInsertPoint()` that's getting called will then call `PrevInsertPoint->getParent()`, which explodes horribly. The only reason this hasn't blown up is that it's fairly unlikely the builder is adding to the end of the block; usually, we're adding instructions somewhere before the terminator. llvm-svn: 249925
2015-10-10 08:53:03 +08:00
for (auto &I : F.args())
if (I.getType()->isPointerTy()) // Add all pointer arguments.
Pointers.insert(&I);
for (Instruction &Inst : instructions(F)) {
if (Inst.getType()->isPointerTy()) // Add all pointer instructions.
Pointers.insert(&Inst);
if (EvalAAMD && isa<LoadInst>(&Inst))
Loads.insert(&Inst);
if (EvalAAMD && isa<StoreInst>(&Inst))
Stores.insert(&Inst);
if (auto *Call = dyn_cast<CallBase>(&Inst)) {
Value *Callee = Call->getCalledOperand();
// Skip actual functions for direct function calls.
if (!isa<Function>(Callee) && isInterestingPointer(Callee))
Pointers.insert(Callee);
// Consider formals.
for (Use &DataOp : Call->data_ops())
if (isInterestingPointer(DataOp))
Pointers.insert(DataOp);
Calls.insert(Call);
} else {
// Consider all operands.
for (Use &Op : Inst.operands())
if (isInterestingPointer(Op))
Pointers.insert(Op);
}
}
if (PrintAll || PrintNoAlias || PrintMayAlias || PrintPartialAlias ||
PrintMustAlias || PrintNoModRef || PrintMod || PrintRef || PrintModRef)
errs() << "Function: " << F.getName() << ": " << Pointers.size()
<< " pointers, " << Calls.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) {
auto I1Size = LocationSize::afterPointer();
Type *I1ElTy = cast<PointerType>((*I1)->getType())->getElementType();
if (I1ElTy->isSized())
I1Size = LocationSize::precise(DL.getTypeStoreSize(I1ElTy));
for (SetVector<Value *>::iterator I2 = Pointers.begin(); I2 != I1; ++I2) {
auto I2Size = LocationSize::afterPointer();
Type *I2ElTy = cast<PointerType>((*I2)->getType())->getElementType();
if (I2ElTy->isSized())
I2Size = LocationSize::precise(DL.getTypeStoreSize(I2ElTy));
AliasResult AR = AA.alias(*I1, I1Size, *I2, I2Size);
switch (AR) {
case NoAlias:
PrintResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
++NoAliasCount;
break;
case MayAlias:
PrintResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
++MayAliasCount;
break;
case PartialAlias:
PrintResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
++PartialAliasCount;
break;
case MustAlias:
PrintResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
++MustAliasCount;
break;
}
}
}
if (EvalAAMD) {
// iterate over all pairs of load, store
for (Value *Load : Loads) {
for (Value *Store : Stores) {
AliasResult AR = AA.alias(MemoryLocation::get(cast<LoadInst>(Load)),
MemoryLocation::get(cast<StoreInst>(Store)));
switch (AR) {
case NoAlias:
PrintLoadStoreResults(AR, PrintNoAlias, Load, Store, F.getParent());
++NoAliasCount;
break;
case MayAlias:
PrintLoadStoreResults(AR, PrintMayAlias, Load, Store, F.getParent());
++MayAliasCount;
break;
case PartialAlias:
PrintLoadStoreResults(AR, PrintPartialAlias, Load, Store, F.getParent());
++PartialAliasCount;
break;
case MustAlias:
PrintLoadStoreResults(AR, PrintMustAlias, Load, Store, F.getParent());
++MustAliasCount;
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) {
AliasResult AR = AA.alias(MemoryLocation::get(cast<StoreInst>(*I1)),
MemoryLocation::get(cast<StoreInst>(*I2)));
switch (AR) {
case NoAlias:
PrintLoadStoreResults(AR, PrintNoAlias, *I1, *I2, F.getParent());
++NoAliasCount;
break;
case MayAlias:
PrintLoadStoreResults(AR, PrintMayAlias, *I1, *I2, F.getParent());
++MayAliasCount;
break;
case PartialAlias:
PrintLoadStoreResults(AR, PrintPartialAlias, *I1, *I2, F.getParent());
++PartialAliasCount;
break;
case MustAlias:
PrintLoadStoreResults(AR, PrintMustAlias, *I1, *I2, F.getParent());
++MustAliasCount;
break;
}
}
}
}
// Mod/ref alias analysis: compare all pairs of calls and values
for (CallBase *Call : Calls) {
for (auto Pointer : Pointers) {
auto Size = LocationSize::afterPointer();
Type *ElTy = cast<PointerType>(Pointer->getType())->getElementType();
if (ElTy->isSized())
Size = LocationSize::precise(DL.getTypeStoreSize(ElTy));
switch (AA.getModRefInfo(Call, Pointer, Size)) {
case ModRefInfo::NoModRef:
PrintModRefResults("NoModRef", PrintNoModRef, Call, Pointer,
F.getParent());
++NoModRefCount;
break;
case ModRefInfo::Mod:
PrintModRefResults("Just Mod", PrintMod, Call, Pointer, F.getParent());
++ModCount;
break;
case ModRefInfo::Ref:
PrintModRefResults("Just Ref", PrintRef, Call, Pointer, F.getParent());
++RefCount;
break;
case ModRefInfo::ModRef:
PrintModRefResults("Both ModRef", PrintModRef, Call, Pointer,
F.getParent());
++ModRefCount;
break;
case ModRefInfo::Must:
PrintModRefResults("Must", PrintMust, Call, Pointer, F.getParent());
++MustCount;
break;
case ModRefInfo::MustMod:
PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, Call, Pointer,
F.getParent());
++MustModCount;
break;
case ModRefInfo::MustRef:
PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, Call, Pointer,
F.getParent());
++MustRefCount;
break;
case ModRefInfo::MustModRef:
PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, Call,
Pointer, F.getParent());
++MustModRefCount;
break;
}
}
}
// Mod/ref alias analysis: compare all pairs of calls
for (CallBase *CallA : Calls) {
for (CallBase *CallB : Calls) {
if (CallA == CallB)
continue;
switch (AA.getModRefInfo(CallA, CallB)) {
case ModRefInfo::NoModRef:
PrintModRefResults("NoModRef", PrintNoModRef, CallA, CallB,
F.getParent());
++NoModRefCount;
break;
case ModRefInfo::Mod:
PrintModRefResults("Just Mod", PrintMod, CallA, CallB, F.getParent());
++ModCount;
break;
case ModRefInfo::Ref:
PrintModRefResults("Just Ref", PrintRef, CallA, CallB, F.getParent());
++RefCount;
break;
case ModRefInfo::ModRef:
PrintModRefResults("Both ModRef", PrintModRef, CallA, CallB,
F.getParent());
++ModRefCount;
break;
case ModRefInfo::Must:
PrintModRefResults("Must", PrintMust, CallA, CallB, F.getParent());
++MustCount;
break;
case ModRefInfo::MustMod:
PrintModRefResults("Just Mod (MustAlias)", PrintMustMod, CallA, CallB,
F.getParent());
++MustModCount;
break;
case ModRefInfo::MustRef:
PrintModRefResults("Just Ref (MustAlias)", PrintMustRef, CallA, CallB,
F.getParent());
++MustRefCount;
break;
case ModRefInfo::MustModRef:
PrintModRefResults("Both ModRef (MustAlias)", PrintMustModRef, CallA,
CallB, F.getParent());
++MustModRefCount;
break;
}
}
}
}
static void PrintPercent(int64_t Num, int64_t Sum) {
errs() << "(" << Num * 100LL / Sum << "." << ((Num * 1000LL / Sum) % 10)
<< "%)\n";
}
AAEvaluator::~AAEvaluator() {
if (FunctionCount == 0)
return;
int64_t AliasSum =
NoAliasCount + MayAliasCount + PartialAliasCount + MustAliasCount;
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() << " " << NoAliasCount << " no alias responses ";
PrintPercent(NoAliasCount, AliasSum);
errs() << " " << MayAliasCount << " may alias responses ";
PrintPercent(MayAliasCount, AliasSum);
errs() << " " << PartialAliasCount << " partial alias responses ";
PrintPercent(PartialAliasCount, AliasSum);
errs() << " " << MustAliasCount << " must alias responses ";
PrintPercent(MustAliasCount, AliasSum);
errs() << " Alias Analysis Evaluator Pointer Alias Summary: "
<< NoAliasCount * 100 / AliasSum << "%/"
<< MayAliasCount * 100 / AliasSum << "%/"
<< PartialAliasCount * 100 / AliasSum << "%/"
<< MustAliasCount * 100 / AliasSum << "%\n";
}
// Display the summary for mod/ref analysis
int64_t ModRefSum = NoModRefCount + RefCount + ModCount + ModRefCount +
MustCount + MustRefCount + MustModCount + MustModRefCount;
if (ModRefSum == 0) {
errs() << " Alias Analysis Mod/Ref Evaluator Summary: no "
"mod/ref!\n";
} else {
errs() << " " << ModRefSum << " Total ModRef Queries Performed\n";
errs() << " " << NoModRefCount << " no mod/ref responses ";
PrintPercent(NoModRefCount, ModRefSum);
errs() << " " << ModCount << " mod responses ";
PrintPercent(ModCount, ModRefSum);
errs() << " " << RefCount << " ref responses ";
PrintPercent(RefCount, ModRefSum);
errs() << " " << ModRefCount << " mod & ref responses ";
PrintPercent(ModRefCount, ModRefSum);
errs() << " " << MustCount << " must responses ";
PrintPercent(MustCount, ModRefSum);
errs() << " " << MustModCount << " must mod responses ";
PrintPercent(MustModCount, ModRefSum);
errs() << " " << MustRefCount << " must ref responses ";
PrintPercent(MustRefCount, ModRefSum);
errs() << " " << MustModRefCount << " must mod & ref responses ";
PrintPercent(MustModRefCount, ModRefSum);
errs() << " Alias Analysis Evaluator Mod/Ref Summary: "
<< NoModRefCount * 100 / ModRefSum << "%/"
<< ModCount * 100 / ModRefSum << "%/" << RefCount * 100 / ModRefSum
<< "%/" << ModRefCount * 100 / ModRefSum << "%/"
<< MustCount * 100 / ModRefSum << "%/"
<< MustRefCount * 100 / ModRefSum << "%/"
<< MustModCount * 100 / ModRefSum << "%/"
<< MustModRefCount * 100 / ModRefSum << "%\n";
}
}
namespace llvm {
class AAEvalLegacyPass : public FunctionPass {
std::unique_ptr<AAEvaluator> P;
public:
static char ID; // Pass identification, replacement for typeid
AAEvalLegacyPass() : FunctionPass(ID) {
initializeAAEvalLegacyPassPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AAResultsWrapperPass>();
AU.setPreservesAll();
}
bool doInitialization(Module &M) override {
P.reset(new AAEvaluator());
return false;
}
bool runOnFunction(Function &F) override {
P->runInternal(F, getAnalysis<AAResultsWrapperPass>().getAAResults());
return false;
}
bool doFinalization(Module &M) override {
P.reset();
return false;
}
};
}
char AAEvalLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(AAEvalLegacyPass, "aa-eval",
"Exhaustive Alias Analysis Precision Evaluator", false,
true)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_END(AAEvalLegacyPass, "aa-eval",
"Exhaustive Alias Analysis Precision Evaluator", false,
true)
FunctionPass *llvm::createAAEvalPass() { return new AAEvalLegacyPass(); }