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 SimpleAAQueryInfo AAQI; 50 51 TestAnalyses(BasicAATest &Test) 52 : DT(*Test.F), AC(*Test.F), BAA(Test.DL, *Test.F, Test.TLI, AC, &DT), 53 AAQI() {} 54 }; 55 56 llvm::Optional<TestAnalyses> Analyses; 57 58 TestAnalyses &setupAnalyses() { 59 assert(F); 60 Analyses.emplace(*this); 61 return Analyses.getValue(); 62 } 63 64 public: 65 BasicAATest() 66 : M("BasicAATest", C), B(C), DL(DLString), TLI(TLII), F(nullptr) {} 67 }; 68 69 // Check that a function arg can't trivially alias a global when we're accessing 70 // >sizeof(global) bytes through that arg, unless the access size is just an 71 // upper-bound. 72 TEST_F(BasicAATest, AliasInstWithObjectOfImpreciseSize) { 73 F = Function::Create( 74 FunctionType::get(B.getVoidTy(), {B.getInt32Ty()->getPointerTo()}, false), 75 GlobalValue::ExternalLinkage, "F", &M); 76 77 BasicBlock *Entry(BasicBlock::Create(C, "", F)); 78 B.SetInsertPoint(Entry); 79 80 Value *IncomingI32Ptr = F->arg_begin(); 81 82 auto *GlobalPtr = 83 cast<GlobalVariable>(M.getOrInsertGlobal("some_global", B.getInt8Ty())); 84 85 // Without sufficiently restricted linkage/an init, some of the object size 86 // checking bits get more conservative. 87 GlobalPtr->setLinkage(GlobalValue::LinkageTypes::InternalLinkage); 88 GlobalPtr->setInitializer(B.getInt8(0)); 89 90 auto &AllAnalyses = setupAnalyses(); 91 BasicAAResult &BasicAA = AllAnalyses.BAA; 92 AAQueryInfo &AAQI = AllAnalyses.AAQI; 93 ASSERT_EQ( 94 BasicAA.alias(MemoryLocation(IncomingI32Ptr, LocationSize::precise(4)), 95 MemoryLocation(GlobalPtr, LocationSize::precise(1)), AAQI), 96 AliasResult::NoAlias); 97 98 ASSERT_EQ( 99 BasicAA.alias(MemoryLocation(IncomingI32Ptr, LocationSize::upperBound(4)), 100 MemoryLocation(GlobalPtr, LocationSize::precise(1)), AAQI), 101 AliasResult::MayAlias); 102 } 103 104 // Check that we fall back to MayAlias if we see an access of an entire object 105 // that's just an upper-bound. 106 TEST_F(BasicAATest, AliasInstWithFullObjectOfImpreciseSize) { 107 F = Function::Create( 108 FunctionType::get(B.getVoidTy(), {B.getInt64Ty()}, false), 109 GlobalValue::ExternalLinkage, "F", &M); 110 111 BasicBlock *Entry(BasicBlock::Create(C, "", F)); 112 B.SetInsertPoint(Entry); 113 114 Value *ArbitraryI32 = F->arg_begin(); 115 AllocaInst *I8 = B.CreateAlloca(B.getInt8Ty(), B.getInt32(2)); 116 auto *I8AtUncertainOffset = 117 cast<GetElementPtrInst>(B.CreateGEP(B.getInt8Ty(), I8, ArbitraryI32)); 118 119 auto &AllAnalyses = setupAnalyses(); 120 BasicAAResult &BasicAA = AllAnalyses.BAA; 121 AAQueryInfo &AAQI = AllAnalyses.AAQI; 122 ASSERT_EQ(BasicAA.alias( 123 MemoryLocation(I8, LocationSize::precise(2)), 124 MemoryLocation(I8AtUncertainOffset, LocationSize::precise(1)), 125 AAQI), 126 AliasResult::PartialAlias); 127 128 ASSERT_EQ(BasicAA.alias( 129 MemoryLocation(I8, LocationSize::upperBound(2)), 130 MemoryLocation(I8AtUncertainOffset, LocationSize::precise(1)), 131 AAQI), 132 AliasResult::MayAlias); 133 } 134