diff --git a/clang/lib/Analysis/FlowSensitive/Transfer.cpp b/clang/lib/Analysis/FlowSensitive/Transfer.cpp --- a/clang/lib/Analysis/FlowSensitive/Transfer.cpp +++ b/clang/lib/Analysis/FlowSensitive/Transfer.cpp @@ -22,6 +22,7 @@ #include "clang/AST/StmtVisitor.h" #include "clang/Analysis/FlowSensitive/DataflowEnvironment.h" #include "clang/Analysis/FlowSensitive/Value.h" +#include "clang/Basic/Builtins.h" #include "clang/Basic/OperatorKinds.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Support/Casting.h" @@ -455,6 +456,18 @@ return; Env.setStorageLocation(*S, *ArgLoc); + } else if (S->getDirectCallee() != nullptr && + S->getDirectCallee()->getBuiltinID() == + Builtin::BI__builtin_expect) { + assert(S->getNumArgs() > 0); + assert(S->getArg(0) != nullptr); + // `__builtin_expect` returns by-value, so strip away any potential + // references in the argument. + auto *ArgLoc = Env.getStorageLocation( + *S->getArg(0)->IgnoreParenImpCasts(), SkipPast::Reference); + if (ArgLoc == nullptr) + return; + Env.setStorageLocation(*S, *ArgLoc); } } diff --git a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp --- a/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp +++ b/clang/unittests/Analysis/FlowSensitive/TransferTest.cpp @@ -2368,6 +2368,131 @@ }); } +TEST_F(TransferTest, BuiltinExpect) { + std::string Code = R"( + void target(long Foo) { + long Bar = __builtin_expect(Foo, true); + /*[[p]]*/ + } + )"; + runDataflow(Code, + [](llvm::ArrayRef< + std::pair>> + Results, + ASTContext &ASTCtx) { + ASSERT_THAT(Results, ElementsAre(Pair("p", _))); + const auto &Env = Results[0].second.Env; + + const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo"); + ASSERT_THAT(FooDecl, NotNull()); + + const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar"); + ASSERT_THAT(BarDecl, NotNull()); + + EXPECT_EQ(Env.getValue(*FooDecl, SkipPast::None), + Env.getValue(*BarDecl, SkipPast::None)); + }); +} + +TEST_F(TransferTest, BuiltinUnreachable) { + std::string Code = R"( + void target(bool Foo) { + bool Bar = false; + if (Foo) + Bar = Foo; + else + __builtin_unreachable(); + (void)0; + /*[[p]]*/ + } + )"; + runDataflow(Code, + [](llvm::ArrayRef< + std::pair>> + Results, + ASTContext &ASTCtx) { + ASSERT_THAT(Results, ElementsAre(Pair("p", _))); + const auto &Env = Results[0].second.Env; + + const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo"); + ASSERT_THAT(FooDecl, NotNull()); + + const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar"); + ASSERT_THAT(BarDecl, NotNull()); + + // `__builtin_unreachable` promises that the code is + // unreachable, so the compiler treats the "then" branch as the + // only possible predecessor of this statement. + EXPECT_EQ(Env.getValue(*FooDecl, SkipPast::None), + Env.getValue(*BarDecl, SkipPast::None)); + }); +} + +TEST_F(TransferTest, BuiltinTrap) { + std::string Code = R"( + void target(bool Foo) { + bool Bar = false; + if (Foo) + Bar = Foo; + else + __builtin_trap(); + (void)0; + /*[[p]]*/ + } + )"; + runDataflow(Code, + [](llvm::ArrayRef< + std::pair>> + Results, + ASTContext &ASTCtx) { + ASSERT_THAT(Results, ElementsAre(Pair("p", _))); + const auto &Env = Results[0].second.Env; + + const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo"); + ASSERT_THAT(FooDecl, NotNull()); + + const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar"); + ASSERT_THAT(BarDecl, NotNull()); + + // `__builtin_trap` ensures program termination, so only the + // "then" branch is a predecessor of this statement. + EXPECT_EQ(Env.getValue(*FooDecl, SkipPast::None), + Env.getValue(*BarDecl, SkipPast::None)); + }); +} + +TEST_F(TransferTest, BuiltinDebugTrap) { + std::string Code = R"( + void target(bool Foo) { + bool Bar = false; + if (Foo) + Bar = Foo; + else + __builtin_debugtrap(); + (void)0; + /*[[p]]*/ + } + )"; + runDataflow(Code, + [](llvm::ArrayRef< + std::pair>> + Results, + ASTContext &ASTCtx) { + ASSERT_THAT(Results, ElementsAre(Pair("p", _))); + const auto &Env = Results[0].second.Env; + + const ValueDecl *FooDecl = findValueDecl(ASTCtx, "Foo"); + ASSERT_THAT(FooDecl, NotNull()); + + const ValueDecl *BarDecl = findValueDecl(ASTCtx, "Bar"); + ASSERT_THAT(BarDecl, NotNull()); + + // `__builtin_debugtrap` doesn't ensure program termination. + EXPECT_NE(Env.getValue(*FooDecl, SkipPast::None), + Env.getValue(*BarDecl, SkipPast::None)); + }); +} + TEST_F(TransferTest, StaticIntSingleVarDecl) { std::string Code = R"( void target() {