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llvm-project/llvm/unittests/Analysis/AliasAnalysisTest.cpp
Bjorn Pettersson fd05c34b18 Stop using legacy helpers indicating typed pointer types. NFC 
Since we no longer support typed LLVM IR pointer types, the code can
be simplified into for example using PointerType::get directly instead
of using Type::getInt8PtrTy and Type::getInt32PtrTy etc.

Differential Revision: https://reviews.llvm.org/D156733
2023-08-02 12:08:37 +02:00

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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 {
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, const Instruction *) {
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 = PointerType::get(C, 0);
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, std::nullopt), ModRefInfo::Mod);
EXPECT_EQ(AA.getModRefInfo(Load1, MemoryLocation()), ModRefInfo::Ref);
EXPECT_EQ(AA.getModRefInfo(Load1, std::nullopt), ModRefInfo::Ref);
EXPECT_EQ(AA.getModRefInfo(Add1, MemoryLocation()), ModRefInfo::NoModRef);
EXPECT_EQ(AA.getModRefInfo(Add1, std::nullopt), ModRefInfo::NoModRef);
EXPECT_EQ(AA.getModRefInfo(VAArg1, MemoryLocation()), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(VAArg1, std::nullopt), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(CmpXChg1, MemoryLocation()), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(CmpXChg1, std::nullopt), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(AtomicRMW, MemoryLocation()), ModRefInfo::ModRef);
EXPECT_EQ(AA.getModRefInfo(AtomicRMW, std::nullopt), 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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