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4df8efce80
Currently, we have some confusion in the codebase regarding the meaning of LocationSize::unknown(): Some parts (including most of BasicAA) assume that LocationSize::unknown() only allows accesses after the base pointer. Some parts (various callers of AA) assume that LocationSize::unknown() allows accesses both before and after the base pointer (but within the underlying object). This patch splits up LocationSize::unknown() into LocationSize::afterPointer() and LocationSize::beforeOrAfterPointer() to make this completely unambiguous. I tried my best to determine which one is appropriate for all the existing uses. The test changes in cs-cs.ll in particular illustrate a previously clearly incorrect AA result: We were effectively assuming that argmemonly functions were only allowed to access their arguments after the passed pointer, but not before it. I'm pretty sure that this was not intentional, and it's certainly not specified by LangRef that way. Differential Revision: https://reviews.llvm.org/D91649
348 lines
12 KiB
C++
348 lines
12 KiB
C++
//===--- AliasAnalysisTest.cpp - Mixed TBAA unit tests --------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/BasicAliasAnalysis.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/AsmParser/Parser.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/InstIterator.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/IR/Module.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/Support/SourceMgr.h"
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#include "gtest/gtest.h"
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using namespace llvm;
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// Set up some test passes.
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namespace llvm {
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void initializeAATestPassPass(PassRegistry&);
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void initializeTestCustomAAWrapperPassPass(PassRegistry&);
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}
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namespace {
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struct AATestPass : FunctionPass {
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static char ID;
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AATestPass() : FunctionPass(ID) {
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initializeAATestPassPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.addRequired<AAResultsWrapperPass>();
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AU.setPreservesAll();
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}
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bool runOnFunction(Function &F) override {
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AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
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SetVector<Value *> Pointers;
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for (Argument &A : F.args())
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if (A.getType()->isPointerTy())
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Pointers.insert(&A);
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for (Instruction &I : instructions(F))
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if (I.getType()->isPointerTy())
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Pointers.insert(&I);
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for (Value *P1 : Pointers)
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for (Value *P2 : Pointers)
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(void)AA.alias(P1, LocationSize::beforeOrAfterPointer(), P2,
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LocationSize::beforeOrAfterPointer());
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return false;
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}
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};
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}
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char AATestPass::ID = 0;
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INITIALIZE_PASS_BEGIN(AATestPass, "aa-test-pas", "Alias Analysis Test Pass",
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false, true)
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INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
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INITIALIZE_PASS_END(AATestPass, "aa-test-pass", "Alias Analysis Test Pass",
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false, true)
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namespace {
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/// A test customizable AA result. It merely accepts a callback to run whenever
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/// it receives an alias query. Useful for testing that a particular AA result
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/// is reached.
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struct TestCustomAAResult : AAResultBase<TestCustomAAResult> {
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friend AAResultBase<TestCustomAAResult>;
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std::function<void()> CB;
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explicit TestCustomAAResult(std::function<void()> CB)
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: AAResultBase(), CB(std::move(CB)) {}
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TestCustomAAResult(TestCustomAAResult &&Arg)
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: AAResultBase(std::move(Arg)), CB(std::move(Arg.CB)) {}
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bool invalidate(Function &, const PreservedAnalyses &) { return false; }
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AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
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AAQueryInfo &AAQI) {
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CB();
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return MayAlias;
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}
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};
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}
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namespace {
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/// A wrapper pass for the legacy pass manager to use with the above custom AA
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/// result.
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class TestCustomAAWrapperPass : public ImmutablePass {
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std::function<void()> CB;
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std::unique_ptr<TestCustomAAResult> Result;
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public:
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static char ID;
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explicit TestCustomAAWrapperPass(
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std::function<void()> CB = std::function<void()>())
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: ImmutablePass(ID), CB(std::move(CB)) {
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initializeTestCustomAAWrapperPassPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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AU.addRequired<TargetLibraryInfoWrapperPass>();
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}
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bool doInitialization(Module &M) override {
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Result.reset(new TestCustomAAResult(std::move(CB)));
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return true;
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}
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bool doFinalization(Module &M) override {
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Result.reset();
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return true;
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}
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TestCustomAAResult &getResult() { return *Result; }
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const TestCustomAAResult &getResult() const { return *Result; }
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};
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}
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char TestCustomAAWrapperPass::ID = 0;
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INITIALIZE_PASS_BEGIN(TestCustomAAWrapperPass, "test-custom-aa",
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"Test Custom AA Wrapper Pass", false, true)
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INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
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INITIALIZE_PASS_END(TestCustomAAWrapperPass, "test-custom-aa",
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"Test Custom AA Wrapper Pass", false, true)
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namespace {
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class AliasAnalysisTest : public testing::Test {
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protected:
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LLVMContext C;
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Module M;
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TargetLibraryInfoImpl TLII;
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TargetLibraryInfo TLI;
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std::unique_ptr<AssumptionCache> AC;
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std::unique_ptr<BasicAAResult> BAR;
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std::unique_ptr<AAResults> AAR;
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AliasAnalysisTest() : M("AliasAnalysisTest", C), TLI(TLII) {}
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AAResults &getAAResults(Function &F) {
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// Reset the Function AA results first to clear out any references.
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AAR.reset(new AAResults(TLI));
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// Build the various AA results and register them.
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AC.reset(new AssumptionCache(F));
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BAR.reset(new BasicAAResult(M.getDataLayout(), F, TLI, *AC));
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AAR->addAAResult(*BAR);
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return *AAR;
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}
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};
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TEST_F(AliasAnalysisTest, getModRefInfo) {
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// Setup function.
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FunctionType *FTy =
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FunctionType::get(Type::getVoidTy(C), std::vector<Type *>(), false);
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auto *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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auto *BB = BasicBlock::Create(C, "entry", F);
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auto IntType = Type::getInt32Ty(C);
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auto PtrType = Type::getInt32PtrTy(C);
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auto *Value = ConstantInt::get(IntType, 42);
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auto *Addr = ConstantPointerNull::get(PtrType);
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auto Alignment = Align(IntType->getBitWidth() / 8);
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auto *Store1 = new StoreInst(Value, Addr, BB);
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auto *Load1 = new LoadInst(IntType, Addr, "load", BB);
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auto *Add1 = BinaryOperator::CreateAdd(Value, Value, "add", BB);
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auto *VAArg1 = new VAArgInst(Addr, PtrType, "vaarg", BB);
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auto *CmpXChg1 = new AtomicCmpXchgInst(
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Addr, ConstantInt::get(IntType, 0), ConstantInt::get(IntType, 1),
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Alignment, AtomicOrdering::Monotonic, AtomicOrdering::Monotonic,
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SyncScope::System, BB);
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auto *AtomicRMW = new AtomicRMWInst(
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AtomicRMWInst::Xchg, Addr, ConstantInt::get(IntType, 1), Alignment,
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AtomicOrdering::Monotonic, SyncScope::System, BB);
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ReturnInst::Create(C, nullptr, BB);
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auto &AA = getAAResults(*F);
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// Check basic results
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EXPECT_EQ(AA.getModRefInfo(Store1, MemoryLocation()), ModRefInfo::Mod);
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EXPECT_EQ(AA.getModRefInfo(Store1, None), ModRefInfo::Mod);
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EXPECT_EQ(AA.getModRefInfo(Load1, MemoryLocation()), ModRefInfo::Ref);
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EXPECT_EQ(AA.getModRefInfo(Load1, None), ModRefInfo::Ref);
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EXPECT_EQ(AA.getModRefInfo(Add1, MemoryLocation()), ModRefInfo::NoModRef);
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EXPECT_EQ(AA.getModRefInfo(Add1, None), ModRefInfo::NoModRef);
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EXPECT_EQ(AA.getModRefInfo(VAArg1, MemoryLocation()), ModRefInfo::ModRef);
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EXPECT_EQ(AA.getModRefInfo(VAArg1, None), ModRefInfo::ModRef);
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EXPECT_EQ(AA.getModRefInfo(CmpXChg1, MemoryLocation()), ModRefInfo::ModRef);
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EXPECT_EQ(AA.getModRefInfo(CmpXChg1, None), ModRefInfo::ModRef);
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EXPECT_EQ(AA.getModRefInfo(AtomicRMW, MemoryLocation()), ModRefInfo::ModRef);
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EXPECT_EQ(AA.getModRefInfo(AtomicRMW, None), ModRefInfo::ModRef);
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}
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static Instruction *getInstructionByName(Function &F, StringRef Name) {
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for (auto &I : instructions(F))
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if (I.getName() == Name)
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return &I;
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llvm_unreachable("Expected to find instruction!");
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}
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TEST_F(AliasAnalysisTest, BatchAAPhiCycles) {
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LLVMContext C;
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SMDiagnostic Err;
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std::unique_ptr<Module> M = parseAssemblyString(R"(
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define void @f(i8* noalias %a, i1 %c) {
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entry:
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br label %loop
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loop:
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%phi = phi i8* [ null, %entry ], [ %a2, %loop ]
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%offset1 = phi i64 [ 0, %entry ], [ %offset2, %loop]
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%offset2 = add i64 %offset1, 1
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%a1 = getelementptr i8, i8* %a, i64 %offset1
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%a2 = getelementptr i8, i8* %a, i64 %offset2
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%s1 = select i1 %c, i8* %a1, i8* %phi
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%s2 = select i1 %c, i8* %a2, i8* %a1
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br label %loop
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}
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)", Err, C);
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Function *F = M->getFunction("f");
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Instruction *Phi = getInstructionByName(*F, "phi");
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Instruction *A1 = getInstructionByName(*F, "a1");
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Instruction *A2 = getInstructionByName(*F, "a2");
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Instruction *S1 = getInstructionByName(*F, "s1");
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Instruction *S2 = getInstructionByName(*F, "s2");
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MemoryLocation PhiLoc(Phi, LocationSize::precise(1));
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MemoryLocation A1Loc(A1, LocationSize::precise(1));
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MemoryLocation A2Loc(A2, LocationSize::precise(1));
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MemoryLocation S1Loc(S1, LocationSize::precise(1));
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MemoryLocation S2Loc(S2, LocationSize::precise(1));
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auto &AA = getAAResults(*F);
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EXPECT_EQ(NoAlias, AA.alias(A1Loc, A2Loc));
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EXPECT_EQ(MayAlias, AA.alias(PhiLoc, A1Loc));
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EXPECT_EQ(MayAlias, AA.alias(S1Loc, S2Loc));
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BatchAAResults BatchAA(AA);
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EXPECT_EQ(NoAlias, BatchAA.alias(A1Loc, A2Loc));
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EXPECT_EQ(MayAlias, BatchAA.alias(PhiLoc, A1Loc));
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EXPECT_EQ(MayAlias, BatchAA.alias(S1Loc, S2Loc));
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BatchAAResults BatchAA2(AA);
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EXPECT_EQ(NoAlias, BatchAA2.alias(A1Loc, A2Loc));
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EXPECT_EQ(MayAlias, BatchAA2.alias(S1Loc, S2Loc));
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EXPECT_EQ(MayAlias, BatchAA2.alias(PhiLoc, A1Loc));
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}
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TEST_F(AliasAnalysisTest, BatchAAPhiAssumption) {
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LLVMContext C;
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SMDiagnostic Err;
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std::unique_ptr<Module> M = parseAssemblyString(R"(
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define void @f(i8* %a.base, i8* %b.base, i1 %c) {
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entry:
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br label %loop
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loop:
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%a = phi i8* [ %a.next, %loop ], [ %a.base, %entry ]
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%b = phi i8* [ %b.next, %loop ], [ %b.base, %entry ]
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%a.next = getelementptr i8, i8* %a, i64 1
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%b.next = getelementptr i8, i8* %b, i64 1
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br label %loop
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}
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)", Err, C);
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Function *F = M->getFunction("f");
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Instruction *A = getInstructionByName(*F, "a");
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Instruction *B = getInstructionByName(*F, "b");
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Instruction *ANext = getInstructionByName(*F, "a.next");
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Instruction *BNext = getInstructionByName(*F, "b.next");
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MemoryLocation ALoc(A, LocationSize::precise(1));
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MemoryLocation BLoc(B, LocationSize::precise(1));
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MemoryLocation ANextLoc(ANext, LocationSize::precise(1));
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MemoryLocation BNextLoc(BNext, LocationSize::precise(1));
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auto &AA = getAAResults(*F);
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EXPECT_EQ(MayAlias, AA.alias(ALoc, BLoc));
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EXPECT_EQ(MayAlias, AA.alias(ANextLoc, BNextLoc));
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BatchAAResults BatchAA(AA);
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EXPECT_EQ(MayAlias, BatchAA.alias(ALoc, BLoc));
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// TODO: This is incorrect.
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EXPECT_EQ(NoAlias, BatchAA.alias(ANextLoc, BNextLoc));
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}
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class AAPassInfraTest : public testing::Test {
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protected:
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LLVMContext C;
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SMDiagnostic Err;
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std::unique_ptr<Module> M;
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public:
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AAPassInfraTest()
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: M(parseAssemblyString("define i32 @f(i32* %x, i32* %y) {\n"
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"entry:\n"
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" %lx = load i32, i32* %x\n"
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" %ly = load i32, i32* %y\n"
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" %sum = add i32 %lx, %ly\n"
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" ret i32 %sum\n"
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"}\n",
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Err, C)) {
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assert(M && "Failed to build the module!");
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}
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};
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TEST_F(AAPassInfraTest, injectExternalAA) {
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legacy::PassManager PM;
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// Register our custom AA's wrapper pass manually.
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bool IsCustomAAQueried = false;
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PM.add(new TestCustomAAWrapperPass([&] { IsCustomAAQueried = true; }));
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// Now add the external AA wrapper with a lambda which queries for the
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// wrapper around our custom AA and adds it to the results.
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PM.add(createExternalAAWrapperPass([](Pass &P, Function &, AAResults &AAR) {
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if (auto *WrapperPass = P.getAnalysisIfAvailable<TestCustomAAWrapperPass>())
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AAR.addAAResult(WrapperPass->getResult());
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}));
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// And run a pass that will make some alias queries. This will automatically
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// trigger the rest of the alias analysis stack to be run. It is analagous to
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// building a full pass pipeline with any of the existing pass manager
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// builders.
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PM.add(new AATestPass());
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PM.run(*M);
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// Finally, ensure that our custom AA was indeed queried.
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EXPECT_TRUE(IsCustomAAQueried);
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}
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} // end anonymous namspace
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