1 //===- unittests/StaticAnalyzer/SvalTest.cpp ------------------------------===//
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 "CheckerRegistration.h"
10 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/Decl.h"
13 #include "clang/AST/DeclGroup.h"
14 #include "clang/AST/RecursiveASTVisitor.h"
15 #include "clang/AST/Stmt.h"
16 #include "clang/AST/Type.h"
17 #include "clang/StaticAnalyzer/Core/Checker.h"
18 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
22 #include "clang/StaticAnalyzer/Frontend/AnalysisConsumer.h"
23 #include "clang/StaticAnalyzer/Frontend/CheckerRegistry.h"
24 #include "clang/Testing/TestClangConfig.h"
25 #include "clang/Tooling/Tooling.h"
26 #include "llvm/ADT/STLExtras.h"
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/Support/Casting.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include "gtest/gtest.h"
31 
32 namespace clang {
33 
34 // getType() tests include whole bunch of type comparisons,
35 // so when something is wrong, it's good to have gtest telling us
36 // what are those types.
37 LLVM_ATTRIBUTE_UNUSED std::ostream &operator<<(std::ostream &OS,
38                                                const QualType &T) {
39   return OS << T.getAsString();
40 }
41 
42 LLVM_ATTRIBUTE_UNUSED std::ostream &operator<<(std::ostream &OS,
43                                                const CanQualType &T) {
44   return OS << QualType{T};
45 }
46 
47 namespace ento {
48 namespace {
49 
50 //===----------------------------------------------------------------------===//
51 //                       Testing framework implementation
52 //===----------------------------------------------------------------------===//
53 
54 /// A simple map from variable names to symbolic values used to init them.
55 using SVals = llvm::StringMap<SVal>;
56 
57 /// SValCollector is the barebone of all tests.
58 ///
59 /// It is implemented as a checker and reacts to binds, so we find
60 /// symbolic values of interest, and to end analysis, where we actually
61 /// can test whatever we gathered.
62 class SValCollector : public Checker<check::Bind, check::EndAnalysis> {
63 public:
64   void checkBind(SVal Loc, SVal Val, const Stmt *S, CheckerContext &C) const {
65     // Skip instantly if we finished testing.
66     // Also, we care only for binds happening in variable initializations.
67     if (Tested || !isa<DeclStmt>(S))
68       return;
69 
70     if (const auto *VR = llvm::dyn_cast_or_null<VarRegion>(Loc.getAsRegion())) {
71       CollectedSVals[VR->getDescriptiveName(false)] = Val;
72     }
73   }
74 
75   void checkEndAnalysis(ExplodedGraph &G, BugReporter &B,
76                         ExprEngine &Engine) const {
77     if (!Tested) {
78       test(Engine, Engine.getContext());
79       Tested = true;
80       CollectedSVals.clear();
81     }
82   }
83 
84   /// Helper function for tests to access bound symbolic values.
85   SVal getByName(StringRef Name) const { return CollectedSVals[Name]; }
86 
87 private:
88   /// Entry point for tests.
89   virtual void test(ExprEngine &Engine, const ASTContext &Context) const = 0;
90 
91   mutable bool Tested = false;
92   mutable SVals CollectedSVals;
93 };
94 
95 static void expectSameSignAndBitWidth(QualType ExpectedTy, QualType ActualTy,
96                                       const ASTContext &Context) {
97   EXPECT_EQ(ExpectedTy->isUnsignedIntegerType(),
98             ActualTy->isUnsignedIntegerType());
99   EXPECT_EQ(Context.getTypeSize(ExpectedTy), Context.getTypeSize(ActualTy));
100 }
101 
102 // Fixture class for parameterized SValTest
103 class SValTest : public testing::TestWithParam<TestClangConfig> {};
104 
105 // SVAL_TEST is a combined way of providing a short code snippet and
106 // to test some programmatic predicates on symbolic values produced by the
107 // engine for the actual code.
108 //
109 // Each test has a NAME.  One can think of it as a name for normal gtests.
110 //
111 // Each test should provide a CODE snippet.  Code snippets might contain any
112 // valid C/C++, but have ONLY ONE defined function.  There are no requirements
113 // about function's name or parameters.  It can even be a class method.  The
114 // body of the function must contain a set of variable declarations.  Each
115 // variable declaration gets bound to a symbolic value, so for the following
116 // example:
117 //
118 //     int x = <expr>;
119 //
120 // `x` will be bound to whatever symbolic value the engine produced for <expr>.
121 // LIVENESS and REASSIGNMENTS don't affect this binding.
122 //
123 // During the test the actual values can be accessed via `getByName` function,
124 // and, for the `x`-bound value, one must use "x" as its name.
125 //
126 // Example:
127 // SVAL_TEST(SimpleSValTest, R"(
128 // void foo() {
129 //   int x = 42;
130 // })") {
131 //   SVal X = getByName("x");
132 //   EXPECT_TRUE(X.isConstant(42));
133 // }
134 #define SVAL_TEST(NAME, CODE)                                                  \
135   class NAME##SValCollector final : public SValCollector {                     \
136   public:                                                                      \
137     void test(ExprEngine &Engine, const ASTContext &Context) const override;   \
138   };                                                                           \
139                                                                                \
140   void add##NAME##SValCollector(AnalysisASTConsumer &AnalysisConsumer,         \
141                                 AnalyzerOptions &AnOpts) {                     \
142     AnOpts.CheckersAndPackages = {{"test.##NAME##SValCollector", true}};       \
143     AnalysisConsumer.AddCheckerRegistrationFn([](CheckerRegistry &Registry) {  \
144       Registry.addChecker<NAME##SValCollector>("test.##NAME##SValCollector",   \
145                                                "Description", "");             \
146     });                                                                        \
147   }                                                                            \
148                                                                                \
149   TEST_P(SValTest, NAME) {                                                     \
150     EXPECT_TRUE(runCheckerOnCodeWithArgs<add##NAME##SValCollector>(            \
151         CODE, GetParam().getCommandLineArgs()));                               \
152   }                                                                            \
153   void NAME##SValCollector::test(ExprEngine &Engine,                           \
154                                  const ASTContext &Context) const
155 
156 //===----------------------------------------------------------------------===//
157 //                                 Actual tests
158 //===----------------------------------------------------------------------===//
159 
160 SVAL_TEST(GetConstType, R"(
161 void foo() {
162   int x = 42;
163   int *y = nullptr;
164 })") {
165   SVal X = getByName("x");
166   ASSERT_FALSE(X.getType(Context).isNull());
167   EXPECT_EQ(Context.IntTy, X.getType(Context));
168 
169   SVal Y = getByName("y");
170   ASSERT_FALSE(Y.getType(Context).isNull());
171   expectSameSignAndBitWidth(Context.getUIntPtrType(), Y.getType(Context),
172                             Context);
173 }
174 
175 SVAL_TEST(GetLocAsIntType, R"(
176 void foo(int *x) {
177   long int a = (long long int)x;
178   unsigned b = (long long unsigned)&a;
179   int c = (long long int)nullptr;
180 })") {
181   SVal A = getByName("a");
182   ASSERT_FALSE(A.getType(Context).isNull());
183 
184   // TODO: Turn it into signed long
185   expectSameSignAndBitWidth(Context.UnsignedLongTy, A.getType(Context),
186                             Context);
187 
188   SVal B = getByName("b");
189   ASSERT_FALSE(B.getType(Context).isNull());
190   expectSameSignAndBitWidth(Context.UnsignedIntTy, B.getType(Context), Context);
191 
192   SVal C = getByName("c");
193   ASSERT_FALSE(C.getType(Context).isNull());
194   expectSameSignAndBitWidth(Context.IntTy, C.getType(Context), Context);
195 }
196 
197 SVAL_TEST(GetSymExprType, R"(
198 void foo(int a, int b) {
199   int x = a;
200   int y = a + b;
201   long z = a;
202 })") {
203   QualType Int = Context.IntTy;
204 
205   SVal X = getByName("x");
206   ASSERT_FALSE(X.getType(Context).isNull());
207   EXPECT_EQ(Int, X.getType(Context));
208 
209   SVal Y = getByName("y");
210   ASSERT_FALSE(Y.getType(Context).isNull());
211   EXPECT_EQ(Int, Y.getType(Context));
212 
213   // TODO: Change to Long when we support symbolic casts
214   SVal Z = getByName("z");
215   ASSERT_FALSE(Z.getType(Context).isNull());
216   EXPECT_EQ(Int, Z.getType(Context));
217 }
218 
219 SVAL_TEST(GetPointerType, R"(
220 int *bar();
221 int &foobar();
222 struct Z {
223   int a;
224   int *b;
225 };
226 void foo(int x, int *y, Z z) {
227   int &a = x;
228   int &b = *y;
229   int &c = *bar();
230   int &d = foobar();
231   int &e = z.a;
232   int &f = *z.b;
233 })") {
234   QualType Int = Context.IntTy;
235 
236   SVal A = getByName("a");
237   ASSERT_FALSE(A.getType(Context).isNull());
238   const auto *APtrTy = dyn_cast<PointerType>(A.getType(Context));
239   ASSERT_NE(APtrTy, nullptr);
240   EXPECT_EQ(Int, APtrTy->getPointeeType());
241 
242   SVal B = getByName("b");
243   ASSERT_FALSE(B.getType(Context).isNull());
244   const auto *BPtrTy = dyn_cast<PointerType>(B.getType(Context));
245   ASSERT_NE(BPtrTy, nullptr);
246   EXPECT_EQ(Int, BPtrTy->getPointeeType());
247 
248   SVal C = getByName("c");
249   ASSERT_FALSE(C.getType(Context).isNull());
250   const auto *CPtrTy = dyn_cast<PointerType>(C.getType(Context));
251   ASSERT_NE(CPtrTy, nullptr);
252   EXPECT_EQ(Int, CPtrTy->getPointeeType());
253 
254   SVal D = getByName("d");
255   ASSERT_FALSE(D.getType(Context).isNull());
256   const auto *DRefTy = dyn_cast<LValueReferenceType>(D.getType(Context));
257   ASSERT_NE(DRefTy, nullptr);
258   EXPECT_EQ(Int, DRefTy->getPointeeType());
259 
260   SVal E = getByName("e");
261   ASSERT_FALSE(E.getType(Context).isNull());
262   const auto *EPtrTy = dyn_cast<PointerType>(E.getType(Context));
263   ASSERT_NE(EPtrTy, nullptr);
264   EXPECT_EQ(Int, EPtrTy->getPointeeType());
265 
266   SVal F = getByName("f");
267   ASSERT_FALSE(F.getType(Context).isNull());
268   const auto *FPtrTy = dyn_cast<PointerType>(F.getType(Context));
269   ASSERT_NE(FPtrTy, nullptr);
270   EXPECT_EQ(Int, FPtrTy->getPointeeType());
271 }
272 
273 SVAL_TEST(GetCompoundType, R"(
274 struct TestStruct {
275   int a, b;
276 };
277 union TestUnion {
278   int a;
279   float b;
280   TestStruct c;
281 };
282 void foo(int x) {
283   int a[] = {1, x, 2};
284   TestStruct b = {x, 42};
285   TestUnion c = {42};
286   TestUnion d = {.c=b};
287 }
288 )") {
289   SVal A = getByName("a");
290   ASSERT_FALSE(A.getType(Context).isNull());
291   const auto *AArrayType = dyn_cast<ArrayType>(A.getType(Context));
292   ASSERT_NE(AArrayType, nullptr);
293   EXPECT_EQ(Context.IntTy, AArrayType->getElementType());
294 
295   SVal B = getByName("b");
296   ASSERT_FALSE(B.getType(Context).isNull());
297   const auto *BRecordType = dyn_cast<RecordType>(B.getType(Context));
298   ASSERT_NE(BRecordType, nullptr);
299   EXPECT_EQ("TestStruct", BRecordType->getDecl()->getName());
300 
301   SVal C = getByName("c");
302   ASSERT_FALSE(C.getType(Context).isNull());
303   const auto *CRecordType = dyn_cast<RecordType>(C.getType(Context));
304   ASSERT_NE(CRecordType, nullptr);
305   EXPECT_EQ("TestUnion", CRecordType->getDecl()->getName());
306 
307   auto D = getByName("d").getAs<nonloc::CompoundVal>();
308   ASSERT_TRUE(D.has_value());
309   auto Begin = D->begin();
310   ASSERT_NE(D->end(), Begin);
311   ++Begin;
312   ASSERT_EQ(D->end(), Begin);
313   auto LD = D->begin()->getAs<nonloc::LazyCompoundVal>();
314   ASSERT_TRUE(LD.has_value());
315   auto LDT = LD->getType(Context);
316   ASSERT_FALSE(LDT.isNull());
317   const auto *DRecordType = dyn_cast<RecordType>(LDT);
318   ASSERT_NE(DRecordType, nullptr);
319   EXPECT_EQ("TestStruct", DRecordType->getDecl()->getName());
320 }
321 
322 SVAL_TEST(GetStringType, R"(
323 void foo() {
324   const char *a = "Hello, world!";
325 }
326 )") {
327   SVal A = getByName("a");
328   ASSERT_FALSE(A.getType(Context).isNull());
329   const auto *APtrTy = dyn_cast<PointerType>(A.getType(Context));
330   ASSERT_NE(APtrTy, nullptr);
331   EXPECT_EQ(Context.CharTy, APtrTy->getPointeeType());
332 }
333 
334 SVAL_TEST(GetThisType, R"(
335 class TestClass {
336   void foo();
337 };
338 void TestClass::foo() {
339   const auto *a = this;
340 }
341 )") {
342   SVal A = getByName("a");
343   ASSERT_FALSE(A.getType(Context).isNull());
344   const auto *APtrTy = dyn_cast<PointerType>(A.getType(Context));
345   ASSERT_NE(APtrTy, nullptr);
346   const auto *ARecordType = dyn_cast<RecordType>(APtrTy->getPointeeType());
347   ASSERT_NE(ARecordType, nullptr);
348   EXPECT_EQ("TestClass", ARecordType->getDecl()->getName());
349 }
350 
351 SVAL_TEST(GetFunctionPtrType, R"(
352 void bar();
353 void foo() {
354   auto *a = &bar;
355 }
356 )") {
357   SVal A = getByName("a");
358   ASSERT_FALSE(A.getType(Context).isNull());
359   const auto *APtrTy = dyn_cast<PointerType>(A.getType(Context));
360   ASSERT_NE(APtrTy, nullptr);
361   ASSERT_TRUE(isa<FunctionProtoType>(APtrTy->getPointeeType()));
362 }
363 
364 SVAL_TEST(GetLabelType, R"(
365 void foo() {
366   entry:
367   void *a = &&entry;
368   char *b = (char *)&&entry;
369 }
370 )") {
371   SVal A = getByName("a");
372   ASSERT_FALSE(A.getType(Context).isNull());
373   EXPECT_EQ(Context.VoidPtrTy, A.getType(Context));
374 
375   SVal B = getByName("a");
376   ASSERT_FALSE(B.getType(Context).isNull());
377   // TODO: Change to CharTy when we support symbolic casts
378   EXPECT_EQ(Context.VoidPtrTy, B.getType(Context));
379 }
380 
381 std::vector<TestClangConfig> allTestClangConfigs() {
382   std::vector<TestClangConfig> all_configs;
383   TestClangConfig config;
384   config.Language = Lang_CXX14;
385   for (std::string target :
386        {"i686-pc-windows-msvc",   "i686-apple-darwin9",
387         "x86_64-apple-darwin9",   "x86_64-scei-ps4",
388         "x86_64-windows-msvc",    "x86_64-unknown-linux",
389         "x86_64-apple-macosx",    "x86_64-apple-ios14.0",
390         "wasm32-unknown-unknown", "wasm64-unknown-unknown",
391         "thumb-pc-win32",         "sparc64-none-openbsd",
392         "sparc-none-none",        "riscv64-unknown-linux",
393         "ppc64-windows-msvc",     "powerpc-ibm-aix",
394         "powerpc64-ibm-aix",      "s390x-ibm-zos",
395         "armv7-pc-windows-msvc",  "aarch64-pc-windows-msvc",
396         "xcore-xmos-elf"}) {
397     config.Target = target;
398     all_configs.push_back(config);
399   }
400   return all_configs;
401 }
402 
403 INSTANTIATE_TEST_SUITE_P(SValTests, SValTest,
404                          testing::ValuesIn(allTestClangConfigs()));
405 
406 } // namespace
407 } // namespace ento
408 } // namespace clang
409