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-exception 6 // 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 24 using namespace llvm; 25 26 // FIXME: This is duplicated between this file and MemorySSATest. Refactor. 27 const 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 reduce 30 /// that. Tests should mock up a function, store it in F, and then call 31 /// setupAnalyses(). 32 class BasicAATest : public testing::Test { 33 protected: 34 // N.B. Many of these members depend on each other (e.g. the Module depends on 35 // 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 llvm::Optional<TestAnalyses> Analyses; 60 61 TestAnalyses &setupAnalyses() { 62 assert(F); 63 Analyses.emplace(*this); 64 return *Analyses; 65 } 66 67 public: 68 BasicAATest() 69 : M("BasicAATest", C), B(C), DL(DLString), TLI(TLII), F(nullptr) { 70 C.setOpaquePointers(true); 71 } 72 }; 73 74 // Check that a function arg can't trivially alias a global when we're accessing 75 // >sizeof(global) bytes through that arg, unless the access size is just an 76 // upper-bound. 77 TEST_F(BasicAATest, AliasInstWithObjectOfImpreciseSize) { 78 F = Function::Create(FunctionType::get(B.getVoidTy(), {B.getPtrTy()}, false), 79 GlobalValue::ExternalLinkage, "F", &M); 80 81 BasicBlock *Entry(BasicBlock::Create(C, "", F)); 82 B.SetInsertPoint(Entry); 83 84 Value *IncomingI32Ptr = F->arg_begin(); 85 86 auto *GlobalPtr = 87 cast<GlobalVariable>(M.getOrInsertGlobal("some_global", B.getInt8Ty())); 88 89 // Without sufficiently restricted linkage/an init, some of the object size 90 // checking bits get more conservative. 91 GlobalPtr->setLinkage(GlobalValue::LinkageTypes::InternalLinkage); 92 GlobalPtr->setInitializer(B.getInt8(0)); 93 94 auto &AllAnalyses = setupAnalyses(); 95 BasicAAResult &BasicAA = AllAnalyses.BAA; 96 AAQueryInfo &AAQI = AllAnalyses.AAQI; 97 ASSERT_EQ( 98 BasicAA.alias(MemoryLocation(IncomingI32Ptr, LocationSize::precise(4)), 99 MemoryLocation(GlobalPtr, LocationSize::precise(1)), AAQI), 100 AliasResult::NoAlias); 101 102 ASSERT_EQ( 103 BasicAA.alias(MemoryLocation(IncomingI32Ptr, LocationSize::upperBound(4)), 104 MemoryLocation(GlobalPtr, LocationSize::precise(1)), AAQI), 105 AliasResult::MayAlias); 106 } 107 108 // Check that we fall back to MayAlias if we see an access of an entire object 109 // that's just an upper-bound. 110 TEST_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.CreateGEP(B.getInt8Ty(), 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), 130 AliasResult::PartialAlias); 131 132 ASSERT_EQ(BasicAA.alias( 133 MemoryLocation(I8, LocationSize::upperBound(2)), 134 MemoryLocation(I8AtUncertainOffset, LocationSize::precise(1)), 135 AAQI), 136 AliasResult::MayAlias); 137 } 138 139 TEST_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 = 157 cast<GetElementPtrInst>(B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1))); 158 B.CreateBr(End); 159 160 B.SetInsertPoint(B2); 161 auto *Ptr2 = 162 cast<GetElementPtrInst>(B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1))); 163 B.CreateBr(End); 164 165 B.SetInsertPoint(End); 166 auto *Phi = B.CreatePHI(B.getPtrTy(), 2); 167 Phi->addIncoming(Ptr1, B1); 168 Phi->addIncoming(Ptr2, B2); 169 B.CreateRetVoid(); 170 171 auto &AllAnalyses = setupAnalyses(); 172 BasicAAResult &BasicAA = AllAnalyses.BAA; 173 AAQueryInfo &AAQI = AllAnalyses.AAQI; 174 AliasResult AR = 175 BasicAA.alias(MemoryLocation(Ptr, LocationSize::precise(2)), 176 MemoryLocation(Phi, LocationSize::precise(1)), AAQI); 177 ASSERT_EQ(AR.getOffset(), 1); 178 } 179 180 TEST_F(BasicAATest, PartialAliasOffsetSelect) { 181 F = Function::Create( 182 FunctionType::get(B.getVoidTy(), {B.getPtrTy(), B.getInt1Ty()}, false), 183 GlobalValue::ExternalLinkage, "F", &M); 184 185 Value *Ptr = F->arg_begin(); 186 Value *I = F->arg_begin() + 1; 187 188 BasicBlock *Entry(BasicBlock::Create(C, "", F)); 189 B.SetInsertPoint(Entry); 190 191 auto *Ptr1 = 192 cast<GetElementPtrInst>(B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1))); 193 auto *Ptr2 = 194 cast<GetElementPtrInst>(B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1))); 195 auto *Select = B.CreateSelect(I, Ptr1, Ptr2); 196 B.CreateRetVoid(); 197 198 auto &AllAnalyses = setupAnalyses(); 199 BasicAAResult &BasicAA = AllAnalyses.BAA; 200 AAQueryInfo &AAQI = AllAnalyses.AAQI; 201 AliasResult AR = 202 BasicAA.alias(MemoryLocation(Ptr, LocationSize::precise(2)), 203 MemoryLocation(Select, LocationSize::precise(1)), AAQI); 204 ASSERT_EQ(AR.getOffset(), 1); 205 } 206