202 lines · cpp
1//===- BasicAliasAnalysisTest.cpp - Unit tests for BasicAA ----------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// Targeted tests that are hard/convoluted to make happen with just `opt`.10//11 12#include "llvm/Analysis/BasicAliasAnalysis.h"13#include "llvm/Analysis/AliasAnalysis.h"14#include "llvm/Analysis/AssumptionCache.h"15#include "llvm/Analysis/TargetLibraryInfo.h"16#include "llvm/AsmParser/Parser.h"17#include "llvm/IR/Dominators.h"18#include "llvm/IR/IRBuilder.h"19#include "llvm/IR/LLVMContext.h"20#include "llvm/IR/Module.h"21#include "llvm/Support/SourceMgr.h"22#include "gtest/gtest.h"23 24using namespace llvm;25 26// FIXME: This is duplicated between this file and MemorySSATest. Refactor.27const static char DLString[] = "e-i64:64-f80:128-n8:16:32:64-S128";28 29/// There's a lot of common setup between these tests. This fixture helps reduce30/// that. Tests should mock up a function, store it in F, and then call31/// setupAnalyses().32class BasicAATest : public testing::Test {33protected:34 // N.B. Many of these members depend on each other (e.g. the Module depends on35 // the Context, etc.). So, order matters here (and in TestAnalyses).36 LLVMContext C;37 Module M;38 IRBuilder<> B;39 DataLayout DL;40 TargetLibraryInfoImpl TLII;41 TargetLibraryInfo TLI;42 Function *F;43 44 // Things that we need to build after the function is created.45 struct TestAnalyses {46 DominatorTree DT;47 AssumptionCache AC;48 BasicAAResult BAA;49 AAResults AAR;50 SimpleAAQueryInfo AAQI;51 52 TestAnalyses(BasicAATest &Test)53 : DT(*Test.F), AC(*Test.F), BAA(Test.DL, *Test.F, Test.TLI, AC, &DT),54 AAR(Test.TLI), AAQI(AAR) {55 AAR.addAAResult(BAA);56 }57 };58 59 std::optional<TestAnalyses> Analyses;60 61 TestAnalyses &setupAnalyses() {62 assert(F);63 Analyses.emplace(*this);64 return *Analyses;65 }66 67public:68 BasicAATest()69 : M("BasicAATest", C), B(C), DL(DLString), TLII(M.getTargetTriple()),70 TLI(TLII), F(nullptr) {}71};72 73// Check that a function arg can't trivially alias a global when we're accessing74// >sizeof(global) bytes through that arg, unless the access size is just an75// upper-bound.76TEST_F(BasicAATest, AliasInstWithObjectOfImpreciseSize) {77 F = Function::Create(FunctionType::get(B.getVoidTy(), {B.getPtrTy()}, false),78 GlobalValue::ExternalLinkage, "F", &M);79 80 BasicBlock *Entry(BasicBlock::Create(C, "", F));81 B.SetInsertPoint(Entry);82 83 Value *IncomingI32Ptr = F->arg_begin();84 85 auto *GlobalPtr = M.getOrInsertGlobal("some_global", B.getInt8Ty());86 87 // Without sufficiently restricted linkage/an init, some of the object size88 // checking bits get more conservative.89 GlobalPtr->setLinkage(GlobalValue::LinkageTypes::InternalLinkage);90 GlobalPtr->setInitializer(B.getInt8(0));91 92 auto &AllAnalyses = setupAnalyses();93 BasicAAResult &BasicAA = AllAnalyses.BAA;94 AAQueryInfo &AAQI = AllAnalyses.AAQI;95 ASSERT_EQ(96 BasicAA.alias(MemoryLocation(IncomingI32Ptr, LocationSize::precise(4)),97 MemoryLocation(GlobalPtr, LocationSize::precise(1)), AAQI,98 nullptr),99 AliasResult::NoAlias);100 101 ASSERT_EQ(102 BasicAA.alias(MemoryLocation(IncomingI32Ptr, LocationSize::upperBound(4)),103 MemoryLocation(GlobalPtr, LocationSize::precise(1)), AAQI,104 nullptr),105 AliasResult::MayAlias);106}107 108// Check that we fall back to MayAlias if we see an access of an entire object109// that's just an upper-bound.110TEST_F(BasicAATest, AliasInstWithFullObjectOfImpreciseSize) {111 F = Function::Create(112 FunctionType::get(B.getVoidTy(), {B.getInt64Ty()}, false),113 GlobalValue::ExternalLinkage, "F", &M);114 115 BasicBlock *Entry(BasicBlock::Create(C, "", F));116 B.SetInsertPoint(Entry);117 118 Value *ArbitraryI32 = F->arg_begin();119 AllocaInst *I8 = B.CreateAlloca(B.getInt8Ty(), B.getInt32(2));120 auto *I8AtUncertainOffset =121 cast<GetElementPtrInst>(B.CreatePtrAdd(I8, ArbitraryI32));122 123 auto &AllAnalyses = setupAnalyses();124 BasicAAResult &BasicAA = AllAnalyses.BAA;125 AAQueryInfo &AAQI = AllAnalyses.AAQI;126 ASSERT_EQ(BasicAA.alias(127 MemoryLocation(I8, LocationSize::precise(2)),128 MemoryLocation(I8AtUncertainOffset, LocationSize::precise(1)),129 AAQI, nullptr),130 AliasResult::PartialAlias);131 132 ASSERT_EQ(BasicAA.alias(133 MemoryLocation(I8, LocationSize::upperBound(2)),134 MemoryLocation(I8AtUncertainOffset, LocationSize::precise(1)),135 AAQI, nullptr),136 AliasResult::MayAlias);137}138 139TEST_F(BasicAATest, PartialAliasOffsetPhi) {140 F = Function::Create(141 FunctionType::get(B.getVoidTy(), {B.getPtrTy(), B.getInt1Ty()}, false),142 GlobalValue::ExternalLinkage, "F", &M);143 144 Value *Ptr = F->arg_begin();145 Value *I = F->arg_begin() + 1;146 147 BasicBlock *Entry(BasicBlock::Create(C, "", F));148 BasicBlock *B1(BasicBlock::Create(C, "", F));149 BasicBlock *B2(BasicBlock::Create(C, "", F));150 BasicBlock *End(BasicBlock::Create(C, "", F));151 152 B.SetInsertPoint(Entry);153 B.CreateCondBr(I, B1, B2);154 155 B.SetInsertPoint(B1);156 auto *Ptr1 = cast<GetElementPtrInst>(B.CreatePtrAdd(Ptr, B.getInt32(1)));157 B.CreateBr(End);158 159 B.SetInsertPoint(B2);160 auto *Ptr2 = cast<GetElementPtrInst>(B.CreatePtrAdd(Ptr, B.getInt32(1)));161 B.CreateBr(End);162 163 B.SetInsertPoint(End);164 auto *Phi = B.CreatePHI(B.getPtrTy(), 2);165 Phi->addIncoming(Ptr1, B1);166 Phi->addIncoming(Ptr2, B2);167 B.CreateRetVoid();168 169 auto &AllAnalyses = setupAnalyses();170 BasicAAResult &BasicAA = AllAnalyses.BAA;171 AAQueryInfo &AAQI = AllAnalyses.AAQI;172 AliasResult AR = BasicAA.alias(MemoryLocation(Ptr, LocationSize::precise(2)),173 MemoryLocation(Phi, LocationSize::precise(1)),174 AAQI, nullptr);175 ASSERT_EQ(AR.getOffset(), 1);176}177 178TEST_F(BasicAATest, PartialAliasOffsetSelect) {179 F = Function::Create(180 FunctionType::get(B.getVoidTy(), {B.getPtrTy(), B.getInt1Ty()}, false),181 GlobalValue::ExternalLinkage, "F", &M);182 183 Value *Ptr = F->arg_begin();184 Value *I = F->arg_begin() + 1;185 186 BasicBlock *Entry(BasicBlock::Create(C, "", F));187 B.SetInsertPoint(Entry);188 189 auto *Ptr1 = cast<GetElementPtrInst>(B.CreatePtrAdd(Ptr, B.getInt32(1)));190 auto *Ptr2 = cast<GetElementPtrInst>(B.CreatePtrAdd(Ptr, B.getInt32(1)));191 auto *Select = B.CreateSelect(I, Ptr1, Ptr2);192 B.CreateRetVoid();193 194 auto &AllAnalyses = setupAnalyses();195 BasicAAResult &BasicAA = AllAnalyses.BAA;196 AAQueryInfo &AAQI = AllAnalyses.AAQI;197 AliasResult AR = BasicAA.alias(198 MemoryLocation(Ptr, LocationSize::precise(2)),199 MemoryLocation(Select, LocationSize::precise(1)), AAQI, nullptr);200 ASSERT_EQ(AR.getOffset(), 1);201}202