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__anon6d43c8000111::AATestPass36 AATestPass() : FunctionPass(ID) {
37 initializeAATestPassPass(*PassRegistry::getPassRegistry());
38 }
39
getAnalysisUsage__anon6d43c8000111::AATestPass40 void getAnalysisUsage(AnalysisUsage &AU) const override {
41 AU.addRequired<AAResultsWrapperPass>();
42 AU.setPreservesAll();
43 }
44
runOnFunction__anon6d43c8000111::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 {
78 std::function<void()> CB;
79
TestCustomAAResult__anon6d43c8000211::TestCustomAAResult80 explicit TestCustomAAResult(std::function<void()> CB)
81 : AAResultBase(), CB(std::move(CB)) {}
TestCustomAAResult__anon6d43c8000211::TestCustomAAResult82 TestCustomAAResult(TestCustomAAResult &&Arg)
83 : AAResultBase(std::move(Arg)), CB(std::move(Arg.CB)) {}
84
invalidate__anon6d43c8000211::TestCustomAAResult85 bool invalidate(Function &, const PreservedAnalyses &) { return false; }
86
alias__anon6d43c8000211::TestCustomAAResult87 AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
88 AAQueryInfo &AAQI, const Instruction *) {
89 CB();
90 return AliasResult::MayAlias;
91 }
92 };
93 }
94
95 namespace {
96 /// A wrapper pass for the legacy pass manager to use with the above custom AA
97 /// result.
98 class TestCustomAAWrapperPass : public ImmutablePass {
99 std::function<void()> CB;
100 std::unique_ptr<TestCustomAAResult> Result;
101
102 public:
103 static char ID;
104
TestCustomAAWrapperPass(std::function<void ()> CB=std::function<void ()> ())105 explicit TestCustomAAWrapperPass(
106 std::function<void()> CB = std::function<void()>())
107 : ImmutablePass(ID), CB(std::move(CB)) {
108 initializeTestCustomAAWrapperPassPass(*PassRegistry::getPassRegistry());
109 }
110
getAnalysisUsage(AnalysisUsage & AU) const111 void getAnalysisUsage(AnalysisUsage &AU) const override {
112 AU.setPreservesAll();
113 AU.addRequired<TargetLibraryInfoWrapperPass>();
114 }
115
doInitialization(Module & M)116 bool doInitialization(Module &M) override {
117 Result.reset(new TestCustomAAResult(std::move(CB)));
118 return true;
119 }
120
doFinalization(Module & M)121 bool doFinalization(Module &M) override {
122 Result.reset();
123 return true;
124 }
125
getResult()126 TestCustomAAResult &getResult() { return *Result; }
getResult() const127 const TestCustomAAResult &getResult() const { return *Result; }
128 };
129 }
130
131 char TestCustomAAWrapperPass::ID = 0;
132 INITIALIZE_PASS_BEGIN(TestCustomAAWrapperPass, "test-custom-aa",
133 "Test Custom AA Wrapper Pass", false, true)
134 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
135 INITIALIZE_PASS_END(TestCustomAAWrapperPass, "test-custom-aa",
136 "Test Custom AA Wrapper Pass", false, true)
137
138 namespace {
139
140 class AliasAnalysisTest : public testing::Test {
141 protected:
142 LLVMContext C;
143 Module M;
144 TargetLibraryInfoImpl TLII;
145 TargetLibraryInfo TLI;
146 std::unique_ptr<AssumptionCache> AC;
147 std::unique_ptr<BasicAAResult> BAR;
148 std::unique_ptr<AAResults> AAR;
149
AliasAnalysisTest()150 AliasAnalysisTest() : M("AliasAnalysisTest", C), TLI(TLII) {}
151
getAAResults(Function & F)152 AAResults &getAAResults(Function &F) {
153 // Reset the Function AA results first to clear out any references.
154 AAR.reset(new AAResults(TLI));
155
156 // Build the various AA results and register them.
157 AC.reset(new AssumptionCache(F));
158 BAR.reset(new BasicAAResult(M.getDataLayout(), F, TLI, *AC));
159 AAR->addAAResult(*BAR);
160
161 return *AAR;
162 }
163 };
164
TEST_F(AliasAnalysisTest,getModRefInfo)165 TEST_F(AliasAnalysisTest, getModRefInfo) {
166 // Setup function.
167 FunctionType *FTy =
168 FunctionType::get(Type::getVoidTy(C), std::vector<Type *>(), false);
169 auto *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
170 auto *BB = BasicBlock::Create(C, "entry", F);
171 auto IntType = Type::getInt32Ty(C);
172 auto PtrType = PointerType::get(C, 0);
173 auto *Value = ConstantInt::get(IntType, 42);
174 auto *Addr = ConstantPointerNull::get(PtrType);
175 auto Alignment = Align(IntType->getBitWidth() / 8);
176
177 auto *Store1 = new StoreInst(Value, Addr, BB);
178 auto *Load1 = new LoadInst(IntType, Addr, "load", BB);
179 auto *Add1 = BinaryOperator::CreateAdd(Value, Value, "add", BB);
180 auto *VAArg1 = new VAArgInst(Addr, PtrType, "vaarg", BB);
181 auto *CmpXChg1 = new AtomicCmpXchgInst(
182 Addr, ConstantInt::get(IntType, 0), ConstantInt::get(IntType, 1),
183 Alignment, AtomicOrdering::Monotonic, AtomicOrdering::Monotonic,
184 SyncScope::System, BB);
185 auto *AtomicRMW = new AtomicRMWInst(
186 AtomicRMWInst::Xchg, Addr, ConstantInt::get(IntType, 1), Alignment,
187 AtomicOrdering::Monotonic, SyncScope::System, BB);
188
189 ReturnInst::Create(C, nullptr, BB);
190
191 auto &AA = getAAResults(*F);
192
193 // Check basic results
194 EXPECT_EQ(AA.getModRefInfo(Store1, MemoryLocation()), ModRefInfo::Mod);
195 EXPECT_EQ(AA.getModRefInfo(Store1, std::nullopt), ModRefInfo::Mod);
196 EXPECT_EQ(AA.getModRefInfo(Load1, MemoryLocation()), ModRefInfo::Ref);
197 EXPECT_EQ(AA.getModRefInfo(Load1, std::nullopt), ModRefInfo::Ref);
198 EXPECT_EQ(AA.getModRefInfo(Add1, MemoryLocation()), ModRefInfo::NoModRef);
199 EXPECT_EQ(AA.getModRefInfo(Add1, std::nullopt), ModRefInfo::NoModRef);
200 EXPECT_EQ(AA.getModRefInfo(VAArg1, MemoryLocation()), ModRefInfo::ModRef);
201 EXPECT_EQ(AA.getModRefInfo(VAArg1, std::nullopt), ModRefInfo::ModRef);
202 EXPECT_EQ(AA.getModRefInfo(CmpXChg1, MemoryLocation()), ModRefInfo::ModRef);
203 EXPECT_EQ(AA.getModRefInfo(CmpXChg1, std::nullopt), ModRefInfo::ModRef);
204 EXPECT_EQ(AA.getModRefInfo(AtomicRMW, MemoryLocation()), ModRefInfo::ModRef);
205 EXPECT_EQ(AA.getModRefInfo(AtomicRMW, std::nullopt), ModRefInfo::ModRef);
206 }
207
getInstructionByName(Function & F,StringRef Name)208 static Instruction *getInstructionByName(Function &F, StringRef Name) {
209 for (auto &I : instructions(F))
210 if (I.getName() == Name)
211 return &I;
212 llvm_unreachable("Expected to find instruction!");
213 }
214
TEST_F(AliasAnalysisTest,BatchAAPhiCycles)215 TEST_F(AliasAnalysisTest, BatchAAPhiCycles) {
216 LLVMContext C;
217 SMDiagnostic Err;
218 std::unique_ptr<Module> M = parseAssemblyString(R"(
219 define void @f(i8* noalias %a, i1 %c) {
220 entry:
221 br label %loop
222
223 loop:
224 %phi = phi i8* [ null, %entry ], [ %a2, %loop ]
225 %offset1 = phi i64 [ 0, %entry ], [ %offset2, %loop]
226 %offset2 = add i64 %offset1, 1
227 %a1 = getelementptr i8, i8* %a, i64 %offset1
228 %a2 = getelementptr i8, i8* %a, i64 %offset2
229 %s1 = select i1 %c, i8* %a1, i8* %phi
230 %s2 = select i1 %c, i8* %a2, i8* %a1
231 br label %loop
232 }
233 )", Err, C);
234
235 Function *F = M->getFunction("f");
236 Instruction *Phi = getInstructionByName(*F, "phi");
237 Instruction *A1 = getInstructionByName(*F, "a1");
238 Instruction *A2 = getInstructionByName(*F, "a2");
239 Instruction *S1 = getInstructionByName(*F, "s1");
240 Instruction *S2 = getInstructionByName(*F, "s2");
241 MemoryLocation PhiLoc(Phi, LocationSize::precise(1));
242 MemoryLocation A1Loc(A1, LocationSize::precise(1));
243 MemoryLocation A2Loc(A2, LocationSize::precise(1));
244 MemoryLocation S1Loc(S1, LocationSize::precise(1));
245 MemoryLocation S2Loc(S2, LocationSize::precise(1));
246
247 auto &AA = getAAResults(*F);
248 EXPECT_EQ(AliasResult::NoAlias, AA.alias(A1Loc, A2Loc));
249 EXPECT_EQ(AliasResult::MayAlias, AA.alias(PhiLoc, A1Loc));
250 EXPECT_EQ(AliasResult::MayAlias, AA.alias(S1Loc, S2Loc));
251
252 BatchAAResults BatchAA(AA);
253 EXPECT_EQ(AliasResult::NoAlias, BatchAA.alias(A1Loc, A2Loc));
254 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(PhiLoc, A1Loc));
255 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(S1Loc, S2Loc));
256
257 BatchAAResults BatchAA2(AA);
258 EXPECT_EQ(AliasResult::NoAlias, BatchAA2.alias(A1Loc, A2Loc));
259 EXPECT_EQ(AliasResult::MayAlias, BatchAA2.alias(S1Loc, S2Loc));
260 EXPECT_EQ(AliasResult::MayAlias, BatchAA2.alias(PhiLoc, A1Loc));
261 }
262
TEST_F(AliasAnalysisTest,BatchAAPhiAssumption)263 TEST_F(AliasAnalysisTest, BatchAAPhiAssumption) {
264 LLVMContext C;
265 SMDiagnostic Err;
266 std::unique_ptr<Module> M = parseAssemblyString(R"(
267 define void @f(i8* %a.base, i8* %b.base, i1 %c) {
268 entry:
269 br label %loop
270
271 loop:
272 %a = phi i8* [ %a.next, %loop ], [ %a.base, %entry ]
273 %b = phi i8* [ %b.next, %loop ], [ %b.base, %entry ]
274 %a.next = getelementptr i8, i8* %a, i64 1
275 %b.next = getelementptr i8, i8* %b, i64 1
276 br label %loop
277 }
278 )", Err, C);
279
280 Function *F = M->getFunction("f");
281 Instruction *A = getInstructionByName(*F, "a");
282 Instruction *B = getInstructionByName(*F, "b");
283 Instruction *ANext = getInstructionByName(*F, "a.next");
284 Instruction *BNext = getInstructionByName(*F, "b.next");
285 MemoryLocation ALoc(A, LocationSize::precise(1));
286 MemoryLocation BLoc(B, LocationSize::precise(1));
287 MemoryLocation ANextLoc(ANext, LocationSize::precise(1));
288 MemoryLocation BNextLoc(BNext, LocationSize::precise(1));
289
290 auto &AA = getAAResults(*F);
291 EXPECT_EQ(AliasResult::MayAlias, AA.alias(ALoc, BLoc));
292 EXPECT_EQ(AliasResult::MayAlias, AA.alias(ANextLoc, BNextLoc));
293
294 BatchAAResults BatchAA(AA);
295 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(ALoc, BLoc));
296 EXPECT_EQ(AliasResult::MayAlias, BatchAA.alias(ANextLoc, BNextLoc));
297 }
298
299 // Check that two aliased GEPs with non-constant offsets are correctly
300 // analyzed and their relative offset can be requested from AA.
TEST_F(AliasAnalysisTest,PartialAliasOffset)301 TEST_F(AliasAnalysisTest, PartialAliasOffset) {
302 LLVMContext C;
303 SMDiagnostic Err;
304 std::unique_ptr<Module> M = parseAssemblyString(R"(
305 define void @foo(float* %arg, i32 %i) {
306 bb:
307 %i2 = zext i32 %i to i64
308 %i3 = getelementptr inbounds float, float* %arg, i64 %i2
309 %i4 = bitcast float* %i3 to <2 x float>*
310 %L1 = load <2 x float>, <2 x float>* %i4, align 16
311 %i7 = add nuw nsw i32 %i, 1
312 %i8 = zext i32 %i7 to i64
313 %i9 = getelementptr inbounds float, float* %arg, i64 %i8
314 %L2 = load float, float* %i9, align 4
315 ret void
316 }
317 )",
318 Err, C);
319
320 if (!M)
321 Err.print("PartialAliasOffset", errs());
322
323 Function *F = M->getFunction("foo");
324 const auto Loc1 = MemoryLocation::get(getInstructionByName(*F, "L1"));
325 const auto Loc2 = MemoryLocation::get(getInstructionByName(*F, "L2"));
326
327 auto &AA = getAAResults(*F);
328
329 const auto AR = AA.alias(Loc1, Loc2);
330 EXPECT_EQ(AR, AliasResult::PartialAlias);
331 EXPECT_EQ(4, AR.getOffset());
332 }
333
334 // Check that swapping the order of parameters to `AA.alias()` changes offset
335 // sign and that the sign is such that FirstLoc + Offset == SecondLoc.
TEST_F(AliasAnalysisTest,PartialAliasOffsetSign)336 TEST_F(AliasAnalysisTest, PartialAliasOffsetSign) {
337 LLVMContext C;
338 SMDiagnostic Err;
339 std::unique_ptr<Module> M = parseAssemblyString(R"(
340 define void @f(i64* %p) {
341 %L1 = load i64, i64* %p
342 %p.i8 = bitcast i64* %p to i8*
343 %q = getelementptr i8, i8* %p.i8, i32 1
344 %L2 = load i8, i8* %q
345 ret void
346 }
347 )",
348 Err, C);
349
350 if (!M)
351 Err.print("PartialAliasOffsetSign", errs());
352
353 Function *F = M->getFunction("f");
354 const auto Loc1 = MemoryLocation::get(getInstructionByName(*F, "L1"));
355 const auto Loc2 = MemoryLocation::get(getInstructionByName(*F, "L2"));
356
357 auto &AA = getAAResults(*F);
358
359 auto AR = AA.alias(Loc1, Loc2);
360 EXPECT_EQ(AR, AliasResult::PartialAlias);
361 EXPECT_EQ(1, AR.getOffset());
362
363 AR = AA.alias(Loc2, Loc1);
364 EXPECT_EQ(AR, AliasResult::PartialAlias);
365 EXPECT_EQ(-1, AR.getOffset());
366 }
367 class AAPassInfraTest : public testing::Test {
368 protected:
369 LLVMContext C;
370 SMDiagnostic Err;
371 std::unique_ptr<Module> M;
372
373 public:
AAPassInfraTest()374 AAPassInfraTest()
375 : M(parseAssemblyString("define i32 @f(i32* %x, i32* %y) {\n"
376 "entry:\n"
377 " %lx = load i32, i32* %x\n"
378 " %ly = load i32, i32* %y\n"
379 " %sum = add i32 %lx, %ly\n"
380 " ret i32 %sum\n"
381 "}\n",
382 Err, C)) {
383 assert(M && "Failed to build the module!");
384 }
385 };
386
TEST_F(AAPassInfraTest,injectExternalAA)387 TEST_F(AAPassInfraTest, injectExternalAA) {
388 legacy::PassManager PM;
389
390 // Register our custom AA's wrapper pass manually.
391 bool IsCustomAAQueried = false;
392 PM.add(new TestCustomAAWrapperPass([&] { IsCustomAAQueried = true; }));
393
394 // Now add the external AA wrapper with a lambda which queries for the
395 // wrapper around our custom AA and adds it to the results.
396 PM.add(createExternalAAWrapperPass([](Pass &P, Function &, AAResults &AAR) {
397 if (auto *WrapperPass = P.getAnalysisIfAvailable<TestCustomAAWrapperPass>())
398 AAR.addAAResult(WrapperPass->getResult());
399 }));
400
401 // And run a pass that will make some alias queries. This will automatically
402 // trigger the rest of the alias analysis stack to be run. It is analagous to
403 // building a full pass pipeline with any of the existing pass manager
404 // builders.
405 PM.add(new AATestPass());
406 PM.run(*M);
407
408 // Finally, ensure that our custom AA was indeed queried.
409 EXPECT_TRUE(IsCustomAAQueried);
410 }
411
412 } // end anonymous namspace
413