diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h index 33eb42897b8a1..43656c8ded229 100644 --- a/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h +++ b/clang/include/clang/Analysis/FlowSensitive/DataflowAnalysis.h @@ -25,9 +25,13 @@ #include "clang/Analysis/FlowSensitive/ControlFlowContext.h" #include "clang/Analysis/FlowSensitive/DataflowEnvironment.h" #include "clang/Analysis/FlowSensitive/DataflowLattice.h" +#include "clang/Analysis/FlowSensitive/MatchSwitch.h" #include "clang/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.h" +#include "clang/Analysis/FlowSensitive/WatchedLiteralsSolver.h" #include "llvm/ADT/Any.h" #include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/STLFunctionalExtras.h" +#include "llvm/Support/Errc.h" #include "llvm/Support/Error.h" namespace clang { @@ -238,6 +242,60 @@ runDataflowAnalysis( return std::move(BlockStates); } +/// Runs a dataflow analysis over the given function and then runs `Diagnoser` +/// over the results. Returns a list of diagnostics for `FuncDecl` or an +/// error. Currently, errors can occur (at least) because the analysis requires +/// too many iterations over the CFG or the SAT solver times out. +/// +/// The default value of `MaxSATIterations` was chosen based on the following +/// observations: +/// - Non-pathological calls to the solver typically require only a few hundred +/// iterations. +/// - This limit is still low enough to keep runtimes acceptable (on typical +/// machines) in cases where we hit the limit. +template +llvm::Expected> diagnoseFunction( + const FunctionDecl &FuncDecl, ASTContext &ASTCtx, + llvm::function_ref( + const CFGElement &, ASTContext &, + const TransferStateForDiagnostics &)> + Diagnoser, + std::int64_t MaxSATIterations = 1'000'000'000) { + llvm::Expected Context = + ControlFlowContext::build(FuncDecl); + if (!Context) + return Context.takeError(); + + auto OwnedSolver = std::make_unique(MaxSATIterations); + const WatchedLiteralsSolver *Solver = OwnedSolver.get(); + DataflowAnalysisContext AnalysisContext(std::move(OwnedSolver)); + Environment Env(AnalysisContext, FuncDecl); + AnalysisT Analysis(ASTCtx); + std::vector Diagnostics; + if (llvm::Error Err = + runTypeErasedDataflowAnalysis( + *Context, Analysis, Env, + [&ASTCtx, &Diagnoser, &Diagnostics]( + const CFGElement &Elt, + const TypeErasedDataflowAnalysisState &State) mutable { + auto EltDiagnostics = Diagnoser( + Elt, ASTCtx, + TransferStateForDiagnostics( + llvm::any_cast( + State.Lattice.Value), + State.Env)); + llvm::move(EltDiagnostics, std::back_inserter(Diagnostics)); + }) + .takeError()) + return Err; + + if (Solver->reachedLimit()) + return llvm::createStringError(llvm::errc::interrupted, + "SAT solver timed out"); + + return Diagnostics; +} + /// Abstract base class for dataflow "models": reusable analysis components that /// model a particular aspect of program semantics in the `Environment`. For /// example, a model may capture a type and its related functions. diff --git a/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h b/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h index 9a298478c5100..085308f7db54e 100644 --- a/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h +++ b/clang/include/clang/Analysis/FlowSensitive/MatchSwitch.h @@ -48,6 +48,10 @@ template struct TransferState { }; /// A read-only version of TransferState. +/// +/// FIXME: this type is being used as a general (typed) view type for untyped +/// dataflow analysis state, rather than strictly for transfer-function +/// purposes. Move it (and rename it) to DataflowAnalysis.h. template struct TransferStateForDiagnostics { TransferStateForDiagnostics(const LatticeT &Lattice, const Environment &Env) : Lattice(Lattice), Env(Env) {} diff --git a/clang/include/clang/Analysis/FlowSensitive/NoopAnalysis.h b/clang/include/clang/Analysis/FlowSensitive/NoopAnalysis.h index e28a7f902faf1..016b6b3ba0145 100644 --- a/clang/include/clang/Analysis/FlowSensitive/NoopAnalysis.h +++ b/clang/include/clang/Analysis/FlowSensitive/NoopAnalysis.h @@ -24,6 +24,9 @@ namespace dataflow { class NoopAnalysis : public DataflowAnalysis { public: + NoopAnalysis(ASTContext &Context) + : DataflowAnalysis(Context) {} + /// Deprecated. Use the `DataflowAnalysisOptions` constructor instead. NoopAnalysis(ASTContext &Context, bool ApplyBuiltinTransfer) : DataflowAnalysis(Context, diff --git a/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp b/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp index 462ffb5eb389c..44d6fec962ab5 100644 --- a/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp +++ b/clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp @@ -47,6 +47,7 @@ using namespace test; using namespace ast_matchers; using llvm::IsStringMapEntry; using ::testing::DescribeMatcher; +using ::testing::ElementsAre; using ::testing::IsEmpty; using ::testing::NotNull; using ::testing::Test; @@ -84,6 +85,30 @@ TEST(DataflowAnalysisTest, NoopAnalysis) { EXPECT_TRUE(BlockStates[1].has_value()); } +// Basic test that `diagnoseFunction` calls the Diagnoser function for the +// number of elements expected. +TEST(DataflowAnalysisTest, DiagnoseFunctionDiagnoserCalledOnEachElement) { + std::string Code = R"(void target() { int x = 0; ++x; })"; + std::unique_ptr AST = + tooling::buildASTFromCodeWithArgs(Code, {"-std=c++11"}); + + auto *Func = + cast(findValueDecl(AST->getASTContext(), "target")); + auto Diagnoser = [](const CFGElement &Elt, ASTContext &, + const TransferStateForDiagnostics &) { + std::vector Diagnostics(1); + llvm::raw_string_ostream OS(Diagnostics.front()); + Elt.dumpToStream(OS); + return Diagnostics; + }; + auto Result = diagnoseFunction( + *Func, AST->getASTContext(), Diagnoser); + // `diagnoseFunction` provides no guarantees about the order in which elements + // are visited, so we use `UnorderedElementsAre`. + EXPECT_THAT_EXPECTED(Result, llvm::HasValue(UnorderedElementsAre( + "0\n", "int x = 0;\n", "x\n", "++x\n"))); +} + struct NonConvergingLattice { int State;