1 //===--- AliasAnalysisTest.cpp - Mixed TBAA unit tests --------------------===//
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 #include "llvm/Analysis/AliasAnalysis.h"
10 #include "llvm/ADT/SetVector.h"
11 #include "llvm/Analysis/AssumptionCache.h"
12 #include "llvm/Analysis/BasicAliasAnalysis.h"
13 #include "llvm/Analysis/TargetLibraryInfo.h"
14 #include "llvm/AsmParser/Parser.h"
15 #include "llvm/IR/Constants.h"
16 #include "llvm/IR/InstIterator.h"
17 #include "llvm/IR/Instructions.h"
18 #include "llvm/IR/LLVMContext.h"
19 #include "llvm/IR/LegacyPassManager.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/InitializePasses.h"
22 #include "llvm/Support/SourceMgr.h"
23 #include "gtest/gtest.h"
24
25 using namespace llvm;
26
27 // Set up some test passes.
28 namespace llvm {
29 void initializeAATestPassPass(PassRegistry&);
30 void initializeTestCustomAAWrapperPassPass(PassRegistry&);
31 }
32
33 namespace {
34 struct AATestPass : FunctionPass {
35 static char ID;
AATestPass__anonf787fadb0111::AATestPass36 AATestPass() : FunctionPass(ID) {
37 initializeAATestPassPass(*PassRegistry::getPassRegistry());
38 }
39
getAnalysisUsage__anonf787fadb0111::AATestPass40 void getAnalysisUsage(AnalysisUsage &AU) const override {
41 AU.addRequired<AAResultsWrapperPass>();
42 AU.setPreservesAll();
43 }
44
runOnFunction__anonf787fadb0111::AATestPass45 bool runOnFunction(Function &F) override {
46 AliasAnalysis &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
47
48 SetVector<Value *> Pointers;
49 for (Argument &A : F.args())
50 if (A.getType()->isPointerTy())
51 Pointers.insert(&A);
52 for (Instruction &I : instructions(F))
53 if (I.getType()->isPointerTy())
54 Pointers.insert(&I);
55
56 for (Value *P1 : Pointers)
57 for (Value *P2 : Pointers)
58 (void)AA.alias(P1, LocationSize::beforeOrAfterPointer(), P2,
59 LocationSize::beforeOrAfterPointer());
60
61 return false;
62 }
63 };
64 }
65
66 char AATestPass::ID = 0;
67 INITIALIZE_PASS_BEGIN(AATestPass, "aa-test-pas", "Alias Analysis Test Pass",
68 false, true)
69 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
70 INITIALIZE_PASS_END(AATestPass, "aa-test-pass", "Alias Analysis Test Pass",
71 false, true)
72
73 namespace {
74 /// A test customizable AA result. It merely accepts a callback to run whenever
75 /// it receives an alias query. Useful for testing that a particular AA result
76 /// is reached.
77 struct TestCustomAAResult : AAResultBase<TestCustomAAResult> {
78 friend AAResultBase<TestCustomAAResult>;
79
80 std::function<void()> CB;
81
TestCustomAAResult__anonf787fadb0211::TestCustomAAResult82 explicit TestCustomAAResult(std::function<void()> CB)
83 : AAResultBase(), CB(std::move(CB)) {}
TestCustomAAResult__anonf787fadb0211::TestCustomAAResult84 TestCustomAAResult(TestCustomAAResult &&Arg)
85 : AAResultBase(std::move(Arg)), CB(std::move(Arg.CB)) {}
86
invalidate__anonf787fadb0211::TestCustomAAResult87 bool invalidate(Function &, const PreservedAnalyses &) { return false; }
88
alias__anonf787fadb0211::TestCustomAAResult89 AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
90 AAQueryInfo &AAQI) {
91 CB();
92 return AliasResult::MayAlias;
93 }
94 };
95 }
96
97 namespace {
98 /// A wrapper pass for the legacy pass manager to use with the above custom AA
99 /// result.
100 class TestCustomAAWrapperPass : public ImmutablePass {
101 std::function<void()> CB;
102 std::unique_ptr<TestCustomAAResult> Result;
103
104 public:
105 static char ID;
106
TestCustomAAWrapperPass(std::function<void ()> CB=std::function<void ()> ())107 explicit TestCustomAAWrapperPass(
108 std::function<void()> CB = std::function<void()>())
109 : ImmutablePass(ID), CB(std::move(CB)) {
110 initializeTestCustomAAWrapperPassPass(*PassRegistry::getPassRegistry());
111 }
112
getAnalysisUsage(AnalysisUsage & AU) const113 void getAnalysisUsage(AnalysisUsage &AU) const override {
114 AU.setPreservesAll();
115 AU.addRequired<TargetLibraryInfoWrapperPass>();
116 }
117
doInitialization(Module & M)118 bool doInitialization(Module &M) override {
119 Result.reset(new TestCustomAAResult(std::move(CB)));
120 return true;
121 }
122
doFinalization(Module & M)123 bool doFinalization(Module &M) override {
124 Result.reset();
125 return true;
126 }
127
getResult()128 TestCustomAAResult &getResult() { return *Result; }
getResult() const129 const TestCustomAAResult &getResult() const { return *Result; }
130 };
131 }
132
133 char TestCustomAAWrapperPass::ID = 0;
134 INITIALIZE_PASS_BEGIN(TestCustomAAWrapperPass, "test-custom-aa",
135 "Test Custom AA Wrapper Pass", false, true)
136 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
137 INITIALIZE_PASS_END(TestCustomAAWrapperPass, "test-custom-aa",
138 "Test Custom AA Wrapper Pass", false, true)
139
140 namespace {
141
142 class AliasAnalysisTest : public testing::Test {
143 protected:
144 LLVMContext C;
145 Module M;
146 TargetLibraryInfoImpl TLII;
147 TargetLibraryInfo TLI;
148 std::unique_ptr<AssumptionCache> AC;
149 std::unique_ptr<BasicAAResult> BAR;
150 std::unique_ptr<AAResults> AAR;
151
AliasAnalysisTest()152 AliasAnalysisTest() : M("AliasAnalysisTest", C), TLI(TLII) {}
153
getAAResults(Function & F)154 AAResults &getAAResults(Function &F) {
155 // Reset the Function AA results first to clear out any references.
156 AAR.reset(new AAResults(TLI));
157
158 // Build the various AA results and register them.
159 AC.reset(new AssumptionCache(F));
160 BAR.reset(new BasicAAResult(M.getDataLayout(), F, TLI, *AC));
161 AAR->addAAResult(*BAR);
162
163 return *AAR;
164 }
165 };
166
TEST_F(AliasAnalysisTest,getModRefInfo)167 TEST_F(AliasAnalysisTest, getModRefInfo) {
168 // Setup function.
169 FunctionType *FTy =
170 FunctionType::get(Type::getVoidTy(C), std::vector<Type *>(), false);
171 auto *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
172 auto *BB = BasicBlock::Create(C, "entry", F);
173 auto IntType = Type::getInt32Ty(C);
174 auto PtrType = Type::getInt32PtrTy(C);
175 auto *Value = ConstantInt::get(IntType, 42);
176 auto *Addr = ConstantPointerNull::get(PtrType);
177 auto Alignment = Align(IntType->getBitWidth() / 8);
178
179 auto *Store1 = new StoreInst(Value, Addr, BB);
180 auto *Load1 = new LoadInst(IntType, Addr, "load", BB);
181 auto *Add1 = BinaryOperator::CreateAdd(Value, Value, "add", BB);
182 auto *VAArg1 = new VAArgInst(Addr, PtrType, "vaarg", BB);
183 auto *CmpXChg1 = new AtomicCmpXchgInst(
184 Addr, ConstantInt::get(IntType, 0), ConstantInt::get(IntType, 1),
185 Alignment, AtomicOrdering::Monotonic, AtomicOrdering::Monotonic,
186 SyncScope::System, BB);
187 auto *AtomicRMW = new AtomicRMWInst(
188 AtomicRMWInst::Xchg, Addr, ConstantInt::get(IntType, 1), Alignment,
189 AtomicOrdering::Monotonic, SyncScope::System, BB);
190
191 ReturnInst::Create(C, nullptr, BB);
192
193 auto &AA = getAAResults(*F);
194
195 // Check basic results
196 EXPECT_EQ(AA.getModRefInfo(Store1, MemoryLocation()), ModRefInfo::Mod);
197 EXPECT_EQ(AA.getModRefInfo(Store1, None), ModRefInfo::Mod);
198 EXPECT_EQ(AA.getModRefInfo(Load1, MemoryLocation()), ModRefInfo::Ref);
199 EXPECT_EQ(AA.getModRefInfo(Load1, None), ModRefInfo::Ref);
200 EXPECT_EQ(AA.getModRefInfo(Add1, MemoryLocation()), ModRefInfo::NoModRef);
201 EXPECT_EQ(AA.getModRefInfo(Add1, None), ModRefInfo::NoModRef);
202 EXPECT_EQ(AA.getModRefInfo(VAArg1, MemoryLocation()), ModRefInfo::ModRef);
203 EXPECT_EQ(AA.getModRefInfo(VAArg1, None), ModRefInfo::ModRef);
204 EXPECT_EQ(AA.getModRefInfo(CmpXChg1, MemoryLocation()), ModRefInfo::ModRef);
205 EXPECT_EQ(AA.getModRefInfo(CmpXChg1, None), ModRefInfo::ModRef);
206 EXPECT_EQ(AA.getModRefInfo(AtomicRMW, MemoryLocation()), ModRefInfo::ModRef);
207 EXPECT_EQ(AA.getModRefInfo(AtomicRMW, None), ModRefInfo::ModRef);
208 }
209
getInstructionByName(Function & F,StringRef Name)210 static Instruction *getInstructionByName(Function &F, StringRef Name) {
211 for (auto &I : instructions(F))
212 if (I.getName() == Name)
213 return &I;
214 llvm_unreachable("Expected to find instruction!");
215 }
216
TEST_F(AliasAnalysisTest,BatchAAPhiCycles)217 TEST_F(AliasAnalysisTest, BatchAAPhiCycles) {
218 LLVMContext C;
219 SMDiagnostic Err;
220 std::unique_ptr<Module> M = parseAssemblyString(R"(
221 define void @f(i8* noalias %a, i1 %c) {
222 entry:
223 br label %loop
224
225 loop:
226 %phi = phi i8* [ null, %entry ], [ %a2, %loop ]
227 %offset1 = phi i64 [ 0, %entry ], [ %offset2, %loop]
228 %offset2 = add i64 %offset1, 1
229 %a1 = getelementptr i8, i8* %a, i64 %offset1
230 %a2 = getelementptr i8, i8* %a, i64 %offset2
231 %s1 = select i1 %c, i8* %a1, i8* %phi
232 %s2 = select i1 %c, i8* %a2, i8* %a1
233 br label %loop
234 }
235 )", Err, C);
236
237 Function *F = M->getFunction("f");
238 Instruction *Phi = getInstructionByName(*F, "phi");
239 Instruction *A1 = getInstructionByName(*F, "a1");
240 Instruction *A2 = getInstructionByName(*F, "a2");
241 Instruction *S1 = getInstructionByName(*F, "s1");
242 Instruction *S2 = getInstructionByName(*F, "s2");
243 MemoryLocation PhiLoc(Phi, LocationSize::precise(1));
244 MemoryLocation A1Loc(A1, LocationSize::precise(1));
245 MemoryLocation A2Loc(A2, LocationSize::precise(1));
246 MemoryLocation S1Loc(S1, LocationSize::precise(1));
247 MemoryLocation S2Loc(S2, LocationSize::precise(1));
248
249 auto &AA = getAAResults(*F);
250 EXPECT_EQ(AliasResult::NoAlias, AA.alias(A1Loc, A2Loc));
251 EXPECT_EQ(AliasResult::MayAlias, AA.alias(PhiLoc, A1Loc));
252 EXPECT_EQ(AliasResult::MayAlias, AA.alias(S1Loc, S2Loc));
253
254 BatchAAResults BatchAA(AA);
255 EXPECT_EQ(AliasResult::NoAlias, BatchAA.alias(A1Loc, A2Loc));
256 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(PhiLoc, A1Loc));
257 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(S1Loc, S2Loc));
258
259 BatchAAResults BatchAA2(AA);
260 EXPECT_EQ(AliasResult::NoAlias, BatchAA2.alias(A1Loc, A2Loc));
261 EXPECT_EQ(AliasResult::MayAlias, BatchAA2.alias(S1Loc, S2Loc));
262 EXPECT_EQ(AliasResult::MayAlias, BatchAA2.alias(PhiLoc, A1Loc));
263 }
264
TEST_F(AliasAnalysisTest,BatchAAPhiAssumption)265 TEST_F(AliasAnalysisTest, BatchAAPhiAssumption) {
266 LLVMContext C;
267 SMDiagnostic Err;
268 std::unique_ptr<Module> M = parseAssemblyString(R"(
269 define void @f(i8* %a.base, i8* %b.base, i1 %c) {
270 entry:
271 br label %loop
272
273 loop:
274 %a = phi i8* [ %a.next, %loop ], [ %a.base, %entry ]
275 %b = phi i8* [ %b.next, %loop ], [ %b.base, %entry ]
276 %a.next = getelementptr i8, i8* %a, i64 1
277 %b.next = getelementptr i8, i8* %b, i64 1
278 br label %loop
279 }
280 )", Err, C);
281
282 Function *F = M->getFunction("f");
283 Instruction *A = getInstructionByName(*F, "a");
284 Instruction *B = getInstructionByName(*F, "b");
285 Instruction *ANext = getInstructionByName(*F, "a.next");
286 Instruction *BNext = getInstructionByName(*F, "b.next");
287 MemoryLocation ALoc(A, LocationSize::precise(1));
288 MemoryLocation BLoc(B, LocationSize::precise(1));
289 MemoryLocation ANextLoc(ANext, LocationSize::precise(1));
290 MemoryLocation BNextLoc(BNext, LocationSize::precise(1));
291
292 auto &AA = getAAResults(*F);
293 EXPECT_EQ(AliasResult::MayAlias, AA.alias(ALoc, BLoc));
294 EXPECT_EQ(AliasResult::MayAlias, AA.alias(ANextLoc, BNextLoc));
295
296 BatchAAResults BatchAA(AA);
297 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(ALoc, BLoc));
298 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(ANextLoc, BNextLoc));
299 }
300
301 // Check that two aliased GEPs with non-constant offsets are correctly
302 // analyzed and their relative offset can be requested from AA.
TEST_F(AliasAnalysisTest,PartialAliasOffset)303 TEST_F(AliasAnalysisTest, PartialAliasOffset) {
304 LLVMContext C;
305 SMDiagnostic Err;
306 std::unique_ptr<Module> M = parseAssemblyString(R"(
307 define void @foo(float* %arg, i32 %i) {
308 bb:
309 %i2 = zext i32 %i to i64
310 %i3 = getelementptr inbounds float, float* %arg, i64 %i2
311 %i4 = bitcast float* %i3 to <2 x float>*
312 %L1 = load <2 x float>, <2 x float>* %i4, align 16
313 %i7 = add nuw nsw i32 %i, 1
314 %i8 = zext i32 %i7 to i64
315 %i9 = getelementptr inbounds float, float* %arg, i64 %i8
316 %L2 = load float, float* %i9, align 4
317 ret void
318 }
319 )",
320 Err, C);
321
322 if (!M)
323 Err.print("PartialAliasOffset", errs());
324
325 Function *F = M->getFunction("foo");
326 const auto Loc1 = MemoryLocation::get(getInstructionByName(*F, "L1"));
327 const auto Loc2 = MemoryLocation::get(getInstructionByName(*F, "L2"));
328
329 auto &AA = getAAResults(*F);
330
331 const auto AR = AA.alias(Loc1, Loc2);
332 EXPECT_EQ(AR, AliasResult::PartialAlias);
333 EXPECT_EQ(4, AR.getOffset());
334 }
335
336 class AAPassInfraTest : public testing::Test {
337 protected:
338 LLVMContext C;
339 SMDiagnostic Err;
340 std::unique_ptr<Module> M;
341
342 public:
AAPassInfraTest()343 AAPassInfraTest()
344 : M(parseAssemblyString("define i32 @f(i32* %x, i32* %y) {\n"
345 "entry:\n"
346 " %lx = load i32, i32* %x\n"
347 " %ly = load i32, i32* %y\n"
348 " %sum = add i32 %lx, %ly\n"
349 " ret i32 %sum\n"
350 "}\n",
351 Err, C)) {
352 assert(M && "Failed to build the module!");
353 }
354 };
355
TEST_F(AAPassInfraTest,injectExternalAA)356 TEST_F(AAPassInfraTest, injectExternalAA) {
357 legacy::PassManager PM;
358
359 // Register our custom AA's wrapper pass manually.
360 bool IsCustomAAQueried = false;
361 PM.add(new TestCustomAAWrapperPass([&] { IsCustomAAQueried = true; }));
362
363 // Now add the external AA wrapper with a lambda which queries for the
364 // wrapper around our custom AA and adds it to the results.
365 PM.add(createExternalAAWrapperPass([](Pass &P, Function &, AAResults &AAR) {
366 if (auto *WrapperPass = P.getAnalysisIfAvailable<TestCustomAAWrapperPass>())
367 AAR.addAAResult(WrapperPass->getResult());
368 }));
369
370 // And run a pass that will make some alias queries. This will automatically
371 // trigger the rest of the alias analysis stack to be run. It is analagous to
372 // building a full pass pipeline with any of the existing pass manager
373 // builders.
374 PM.add(new AATestPass());
375 PM.run(*M);
376
377 // Finally, ensure that our custom AA was indeed queried.
378 EXPECT_TRUE(IsCustomAAQueried);
379 }
380
381 } // end anonymous namspace
382