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2ed0e79bb8
SymbolReaper now realizes that our liveness analysis isn't sharp enough to discriminate between liveness of, say, variables and their fields. Surprisingly, this didn't quite work before: having a variable live only through Environment (eg., calling a C++ method on a local variable as the last action ever performed on that variable) would not keep the region value symbol of a field of that variable alive. It would have been broken in the opposite direction as well, but both Environment and RegionStore use the scanReachableSymbols mechanism for finding live symbols regions within their values, and due to that they accidentally end up marking the whole chain of super-regions as live when at least one sub-region is known to be live. It is now a direct responsibility of SymbolReaper to maintain this invariant, and a unit test was added in order to make sure it stays that way. Differential Revision: https://reviews.llvm.org/D56632 rdar://problem/46914108 llvm-svn: 351499
122 lines
4.2 KiB
C++
122 lines
4.2 KiB
C++
//===- unittests/StaticAnalyzer/SymbolReaperTest.cpp ----------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "clang/ASTMatchers/ASTMatchFinder.h"
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#include "clang/Frontend/CompilerInstance.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/CrossTU/CrossTranslationUnit.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
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#include "clang/StaticAnalyzer/Frontend/AnalysisConsumer.h"
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#include "clang/Tooling/Tooling.h"
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#include "gtest/gtest.h"
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namespace clang {
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namespace ento {
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namespace {
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using namespace ast_matchers;
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// A re-usable consumer that constructs ExprEngine out of CompilerInvocation.
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// TODO: Actually re-use it when we write our second test.
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class ExprEngineConsumer : public ASTConsumer {
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protected:
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CompilerInstance &C;
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private:
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// We need to construct all of these in order to construct ExprEngine.
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CheckerManager ChkMgr;
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cross_tu::CrossTranslationUnitContext CTU;
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PathDiagnosticConsumers Consumers;
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AnalysisManager AMgr;
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SetOfConstDecls VisitedCallees;
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FunctionSummariesTy FS;
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protected:
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ExprEngine Eng;
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// Find a declaration in the current AST by name. This has nothing to do
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// with ExprEngine but turns out to be handy.
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// TODO: There's probably a better place for it.
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template <typename T>
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const T *findDeclByName(const Decl *Where, StringRef Name) {
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auto Matcher = decl(hasDescendant(namedDecl(hasName(Name)).bind("d")));
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auto Matches = match(Matcher, *Where, Eng.getContext());
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assert(Matches.size() == 1 && "Ambiguous name!");
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const T *Node = selectFirst<T>("d", Matches);
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assert(Node && "Name not found!");
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return Node;
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}
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public:
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ExprEngineConsumer(CompilerInstance &C)
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: C(C), ChkMgr(C.getASTContext(), *C.getAnalyzerOpts()), CTU(C),
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Consumers(),
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AMgr(C.getASTContext(), C.getDiagnostics(), Consumers,
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CreateRegionStoreManager, CreateRangeConstraintManager, &ChkMgr,
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*C.getAnalyzerOpts()),
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VisitedCallees(), FS(),
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Eng(CTU, AMgr, &VisitedCallees, &FS, ExprEngine::Inline_Regular) {}
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};
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class SuperRegionLivenessConsumer : public ExprEngineConsumer {
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void performTest(const Decl *D) {
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const auto *FD = findDeclByName<FieldDecl>(D, "x");
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const auto *VD = findDeclByName<VarDecl>(D, "s");
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assert(FD && VD);
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// The variable must belong to a stack frame,
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// otherwise SymbolReaper would think it's a global.
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const StackFrameContext *SFC =
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Eng.getAnalysisDeclContextManager().getStackFrame(D);
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// Create regions for 's' and 's.x'.
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const VarRegion *VR = Eng.getRegionManager().getVarRegion(VD, SFC);
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const FieldRegion *FR = Eng.getRegionManager().getFieldRegion(FD, VR);
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// Pass a null location context to the SymbolReaper so that
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// it was thinking that the variable is dead.
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SymbolReaper SymReaper((StackFrameContext *)nullptr, (Stmt *)nullptr,
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Eng.getSymbolManager(), Eng.getStoreManager());
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SymReaper.markLive(FR);
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EXPECT_TRUE(SymReaper.isLiveRegion(VR));
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}
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public:
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SuperRegionLivenessConsumer(CompilerInstance &C) : ExprEngineConsumer(C) {}
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~SuperRegionLivenessConsumer() override {}
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bool HandleTopLevelDecl(DeclGroupRef DG) override {
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for (const auto *D : DG)
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performTest(D);
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return true;
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}
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};
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class SuperRegionLivenessAction: public ASTFrontendAction {
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public:
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SuperRegionLivenessAction() {}
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std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &Compiler,
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StringRef File) override {
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auto Consumer = llvm::make_unique<SuperRegionLivenessConsumer>(Compiler);
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return Consumer;
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}
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};
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// Test that marking s.x as live would also make s live.
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TEST(SymbolReaper, SuperRegionLiveness) {
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EXPECT_TRUE(tooling::runToolOnCode(new SuperRegionLivenessAction,
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"void foo() { struct S { int x; } s; }"));
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}
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} // namespace
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} // namespace ento
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} // namespace clang
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