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llvm-project/llvm/unittests/Analysis/AliasAnalysisTest.cpp

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//===--- AliasAnalysisTest.cpp - Mixed TBAA unit tests --------------------===//
//
// 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/AliasAnalysis.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
using namespace llvm;
// Set up some test passes.
namespace llvm {
void initializeAATestPassPass(PassRegistry&);
void initializeTestCustomAAWrapperPassPass(PassRegistry&);
}
namespace {
struct AATestPass : FunctionPass {
static char ID;
AATestPass() : FunctionPass(ID) {
initializeAATestPassPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AAResultsWrapperPass>();
AU.setPreservesAll();
}
bool runOnFunction(Function &F) override {
AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
SetVector<Value *> Pointers;
for (Argument &A : F.args())
if (A.getType()->isPointerTy())
Pointers.insert(&A);
for (Instruction &I : instructions(F))
if (I.getType()->isPointerTy())
Pointers.insert(&I);
for (Value *P1 : Pointers)
for (Value *P2 : Pointers)
(void)AA.alias(P1, LocationSize::beforeOrAfterPointer(), P2,
LocationSize::beforeOrAfterPointer());
return false;
}
};
}
char AATestPass::ID = 0;
INITIALIZE_PASS_BEGIN(AATestPass, "aa-test-pas", "Alias Analysis Test Pass",
false, true)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_END(AATestPass, "aa-test-pass", "Alias Analysis Test Pass",
false, true)
namespace {
/// A test customizable AA result. It merely accepts a callback to run whenever
/// it receives an alias query. Useful for testing that a particular AA result
/// is reached.
struct TestCustomAAResult : AAResultBase<TestCustomAAResult> {
friend AAResultBase<TestCustomAAResult>;
std::function<void()> CB;
explicit TestCustomAAResult(std::function<void()> CB)
: AAResultBase(), CB(std::move(CB)) {}
TestCustomAAResult(TestCustomAAResult &&Arg)
: AAResultBase(std::move(Arg)), CB(std::move(Arg.CB)) {}
bool invalidate(Function &, const PreservedAnalyses &) { return false; }
AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
AAQueryInfo &AAQI) {
CB();
return AliasResult::MayAlias;
}
};
}
namespace {
/// A wrapper pass for the legacy pass manager to use with the above custom AA
/// result.
class TestCustomAAWrapperPass : public ImmutablePass {
std::function<void()> CB;
std::unique_ptr<TestCustomAAResult> Result;
public:
static char ID;
explicit TestCustomAAWrapperPass(
std::function<void()> CB = std::function<void()>())
: ImmutablePass(ID), CB(std::move(CB)) {
initializeTestCustomAAWrapperPassPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
bool doInitialization(Module &M) override {
Result.reset(new TestCustomAAResult(std::move(CB)));
return true;
}
bool doFinalization(Module &M) override {
Result.reset();
return true;
}
TestCustomAAResult &getResult() { return *Result; }
const TestCustomAAResult &getResult() const { return *Result; }
};
}
char TestCustomAAWrapperPass::ID = 0;
INITIALIZE_PASS_BEGIN(TestCustomAAWrapperPass, "test-custom-aa",
"Test Custom AA Wrapper Pass", false, true)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(TestCustomAAWrapperPass, "test-custom-aa",
"Test Custom AA Wrapper Pass", false, true)
namespace {
class AliasAnalysisTest : public testing::Test {
protected:
LLVMContext C;
Module M;
TargetLibraryInfoImpl TLII;
TargetLibraryInfo TLI;
std::unique_ptr<AssumptionCache> AC;
std::unique_ptr<BasicAAResult> BAR;
std::unique_ptr<AAResults> AAR;
AliasAnalysisTest() : M("AliasAnalysisTest", C), TLI(TLII) {}
AAResults &getAAResults(Function &F) {
// Reset the Function AA results first to clear out any references.
AAR.reset(new AAResults(TLI));
// Build the various AA results and register them.
AC.reset(new AssumptionCache(F));
BAR.reset(new BasicAAResult(M.getDataLayout(), F, TLI, *AC));
AAR->addAAResult(*BAR);
return *AAR;
}
};
TEST_F(AliasAnalysisTest, getModRefInfo) {
// Setup function.
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(C), std::vector<Type *>(), false);
auto *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
auto *BB = BasicBlock::Create(C, "entry", F);
auto IntType = Type::getInt32Ty(C);
auto PtrType = Type::getInt32PtrTy(C);
auto *Value = ConstantInt::get(IntType, 42);
auto *Addr = ConstantPointerNull::get(PtrType);
auto Alignment = Align(IntType->getBitWidth() / 8);
auto *Store1 = new StoreInst(Value, Addr, BB);
auto *Load1 = new LoadInst(IntType, Addr, "load", BB);
auto *Add1 = BinaryOperator::CreateAdd(Value, Value, "add", BB);
auto *VAArg1 = new VAArgInst(Addr, PtrType, "vaarg", BB);
auto *CmpXChg1 = new AtomicCmpXchgInst(
Addr, ConstantInt::get(IntType, 0), ConstantInt::get(IntType, 1),
Alignment, AtomicOrdering::Monotonic, AtomicOrdering::Monotonic,
SyncScope::System, BB);
auto *AtomicRMW = new AtomicRMWInst(
AtomicRMWInst::Xchg, Addr, ConstantInt::get(IntType, 1), Alignment,
AtomicOrdering::Monotonic, SyncScope::System, BB);
ReturnInst::Create(C, nullptr, BB);
auto &AA = getAAResults(*F);
// Check basic results
EXPECT_EQ(AA.getModRefInfo(Store1, MemoryLocation()), ModRefInfo::Mod);
EXPECT_EQ(AA.getModRefInfo(Store1, None), ModRefInfo::Mod);
EXPECT_EQ(AA.getModRefInfo(Load1, MemoryLocation()), ModRefInfo::Ref);
EXPECT_EQ(AA.getModRefInfo(Load1, None), ModRefInfo::Ref);
EXPECT_EQ(AA.getModRefInfo(Add1, MemoryLocation()), ModRefInfo::NoModRef);
EXPECT_EQ(AA.getModRefInfo(Add1, None), ModRefInfo::NoModRef);
EXPECT_EQ(AA.getModRefInfo(VAArg1, MemoryLocation()), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(VAArg1, None), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(CmpXChg1, MemoryLocation()), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(CmpXChg1, None), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(AtomicRMW, MemoryLocation()), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(AtomicRMW, None), ModRefInfo::ModRef);
}
static Instruction *getInstructionByName(Function &F, StringRef Name) {
for (auto &I : instructions(F))
if (I.getName() == Name)
return &I;
llvm_unreachable("Expected to find instruction!");
}
TEST_F(AliasAnalysisTest, BatchAAPhiCycles) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(R"(
define void @f(i8* noalias %a, i1 %c) {
entry:
br label %loop
loop:
%phi = phi i8* [ null, %entry ], [ %a2, %loop ]
%offset1 = phi i64 [ 0, %entry ], [ %offset2, %loop]
%offset2 = add i64 %offset1, 1
%a1 = getelementptr i8, i8* %a, i64 %offset1
%a2 = getelementptr i8, i8* %a, i64 %offset2
%s1 = select i1 %c, i8* %a1, i8* %phi
%s2 = select i1 %c, i8* %a2, i8* %a1
br label %loop
}
)", Err, C);
Function *F = M->getFunction("f");
Instruction *Phi = getInstructionByName(*F, "phi");
Instruction *A1 = getInstructionByName(*F, "a1");
Instruction *A2 = getInstructionByName(*F, "a2");
Instruction *S1 = getInstructionByName(*F, "s1");
Instruction *S2 = getInstructionByName(*F, "s2");
MemoryLocation PhiLoc(Phi, LocationSize::precise(1));
MemoryLocation A1Loc(A1, LocationSize::precise(1));
MemoryLocation A2Loc(A2, LocationSize::precise(1));
MemoryLocation S1Loc(S1, LocationSize::precise(1));
MemoryLocation S2Loc(S2, LocationSize::precise(1));
auto &AA = getAAResults(*F);
EXPECT_EQ(AliasResult::NoAlias, AA.alias(A1Loc, A2Loc));
EXPECT_EQ(AliasResult::MayAlias, AA.alias(PhiLoc, A1Loc));
EXPECT_EQ(AliasResult::MayAlias, AA.alias(S1Loc, S2Loc));
BatchAAResults BatchAA(AA);
EXPECT_EQ(AliasResult::NoAlias, BatchAA.alias(A1Loc, A2Loc));
EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(PhiLoc, A1Loc));
EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(S1Loc, S2Loc));
BatchAAResults BatchAA2(AA);
EXPECT_EQ(AliasResult::NoAlias, BatchAA2.alias(A1Loc, A2Loc));
EXPECT_EQ(AliasResult::MayAlias, BatchAA2.alias(S1Loc, S2Loc));
EXPECT_EQ(AliasResult::MayAlias, BatchAA2.alias(PhiLoc, A1Loc));
}
TEST_F(AliasAnalysisTest, BatchAAPhiAssumption) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(R"(
define void @f(i8* %a.base, i8* %b.base, i1 %c) {
entry:
br label %loop
loop:
%a = phi i8* [ %a.next, %loop ], [ %a.base, %entry ]
%b = phi i8* [ %b.next, %loop ], [ %b.base, %entry ]
%a.next = getelementptr i8, i8* %a, i64 1
%b.next = getelementptr i8, i8* %b, i64 1
br label %loop
}
)", Err, C);
Function *F = M->getFunction("f");
Instruction *A = getInstructionByName(*F, "a");
Instruction *B = getInstructionByName(*F, "b");
Instruction *ANext = getInstructionByName(*F, "a.next");
Instruction *BNext = getInstructionByName(*F, "b.next");
MemoryLocation ALoc(A, LocationSize::precise(1));
MemoryLocation BLoc(B, LocationSize::precise(1));
MemoryLocation ANextLoc(ANext, LocationSize::precise(1));
MemoryLocation BNextLoc(BNext, LocationSize::precise(1));
auto &AA = getAAResults(*F);
EXPECT_EQ(AliasResult::MayAlias, AA.alias(ALoc, BLoc));
EXPECT_EQ(AliasResult::MayAlias, AA.alias(ANextLoc, BNextLoc));
BatchAAResults BatchAA(AA);
EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(ALoc, BLoc));
EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(ANextLoc, BNextLoc));
}
// Check that two aliased GEPs with non-constant offsets are correctly
// analyzed and their relative offset can be requested from AA.
TEST_F(AliasAnalysisTest, PartialAliasOffset) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(R"(
define void @foo(float* %arg, i32 %i) {
bb:
%i2 = zext i32 %i to i64
%i3 = getelementptr inbounds float, float* %arg, i64 %i2
%i4 = bitcast float* %i3 to <2 x float>*
%L1 = load <2 x float>, <2 x float>* %i4, align 16
%i7 = add nuw nsw i32 %i, 1
%i8 = zext i32 %i7 to i64
%i9 = getelementptr inbounds float, float* %arg, i64 %i8
%L2 = load float, float* %i9, align 4
ret void
}
)",
Err, C);
if (!M)
Err.print("PartialAliasOffset", errs());
Function *F = M->getFunction("foo");
const auto Loc1 = MemoryLocation::get(getInstructionByName(*F, "L1"));
const auto Loc2 = MemoryLocation::get(getInstructionByName(*F, "L2"));
auto &AA = getAAResults(*F);
const auto AR = AA.alias(Loc1, Loc2);
EXPECT_EQ(AR, AliasResult::PartialAlias);
EXPECT_EQ(4, AR.getOffset());
}
// Check that swapping the order of parameters to `AA.alias()` changes offset
// sign and that the sign is such that FirstLoc + Offset == SecondLoc.
TEST_F(AliasAnalysisTest, PartialAliasOffsetSign) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(R"(
define void @f(i64* %p) {
%L1 = load i64, i64* %p
%p.i8 = bitcast i64* %p to i8*
%q = getelementptr i8, i8* %p.i8, i32 1
%L2 = load i8, i8* %q
ret void
}
)",
Err, C);
if (!M)
Err.print("PartialAliasOffsetSign", errs());
Function *F = M->getFunction("f");
const auto Loc1 = MemoryLocation::get(getInstructionByName(*F, "L1"));
const auto Loc2 = MemoryLocation::get(getInstructionByName(*F, "L2"));
auto &AA = getAAResults(*F);
auto AR = AA.alias(Loc1, Loc2);
EXPECT_EQ(AR, AliasResult::PartialAlias);
EXPECT_EQ(1, AR.getOffset());
AR = AA.alias(Loc2, Loc1);
EXPECT_EQ(AR, AliasResult::PartialAlias);
EXPECT_EQ(-1, AR.getOffset());
}
class AAPassInfraTest : public testing::Test {
protected:
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M;
public:
AAPassInfraTest()
: M(parseAssemblyString("define i32 @f(i32* %x, i32* %y) {\n"
"entry:\n"
" %lx = load i32, i32* %x\n"
" %ly = load i32, i32* %y\n"
" %sum = add i32 %lx, %ly\n"
" ret i32 %sum\n"
"}\n",
Err, C)) {
assert(M && "Failed to build the module!");
}
};
TEST_F(AAPassInfraTest, injectExternalAA) {
legacy::PassManager PM;
// Register our custom AA's wrapper pass manually.
bool IsCustomAAQueried = false;
PM.add(new TestCustomAAWrapperPass([&] { IsCustomAAQueried = true; }));
// Now add the external AA wrapper with a lambda which queries for the
// wrapper around our custom AA and adds it to the results.
PM.add(createExternalAAWrapperPass([](Pass &P, Function &, AAResults &AAR) {
if (auto *WrapperPass = P.getAnalysisIfAvailable<TestCustomAAWrapperPass>())
AAR.addAAResult(WrapperPass->getResult());
}));
// And run a pass that will make some alias queries. This will automatically
// trigger the rest of the alias analysis stack to be run. It is analagous to
// building a full pass pipeline with any of the existing pass manager
// builders.
PM.add(new AATestPass());
PM.run(*M);
// Finally, ensure that our custom AA was indeed queried.
EXPECT_TRUE(IsCustomAAQueried);
}
} // end anonymous namspace
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