llvm-mirror/unittests/Analysis/AliasAnalysisTest.cpp
Manoj Gupta 647946fa14 llvm: Add support for "-fno-delete-null-pointer-checks"
Summary:
Support for this option is needed for building Linux kernel.
This is a very frequently requested feature by kernel developers.

More details : https://lkml.org/lkml/2018/4/4/601

GCC option description for -fdelete-null-pointer-checks:
This Assume that programs cannot safely dereference null pointers,
and that no code or data element resides at address zero.

-fno-delete-null-pointer-checks is the inverse of this implying that
null pointer dereferencing is not undefined.

This feature is implemented in LLVM IR in this CL as the function attribute
"null-pointer-is-valid"="true" in IR (Under review at D47894).
The CL updates several passes that assumed null pointer dereferencing is
undefined to not optimize when the "null-pointer-is-valid"="true"
attribute is present.

Reviewers: t.p.northover, efriedma, jyknight, chandlerc, rnk, srhines, void, george.burgess.iv

Reviewed By: efriedma, george.burgess.iv

Subscribers: eraman, haicheng, george.burgess.iv, drinkcat, theraven, reames, sanjoy, xbolva00, llvm-commits

Differential Revision: https://reviews.llvm.org/D47895

llvm-svn: 336613
2018-07-09 22:27:23 +00:00

254 lines
8.4 KiB
C++

//===--- AliasAnalysisTest.cpp - Mixed TBAA unit tests --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#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/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, MemoryLocation::UnknownSize, P2,
MemoryLocation::UnknownSize);
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) {
CB();
return 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 = cast<Function>(M.getOrInsertFunction("f", FTy));
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 *Store1 = new StoreInst(Value, Addr, BB);
auto *Load1 = new LoadInst(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),
AtomicOrdering::Monotonic, AtomicOrdering::Monotonic,
SyncScope::System, BB);
auto *AtomicRMW =
new AtomicRMWInst(AtomicRMWInst::Xchg, Addr, ConstantInt::get(IntType, 1),
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);
}
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