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+//== PointerIterationChecker.cpp ------------------------------- -*- C++ -*--=//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines PointerIterationChecker which checks for non-determinism
+// caused due to iteration of unordered containers of pointer elements.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+
+using namespace clang;
+using namespace ento;
+using namespace ast_matchers;
+
+namespace {
+
+// ID of a node at which the diagnostic would be emitted.
+constexpr llvm::StringLiteral WarnAtNode = "iter";
+
+class PointerIterationChecker : public Checker<check::ASTCodeBody> {
+public:
+ void checkASTCodeBody(const Decl *D,
+ AnalysisManager &AM,
+ BugReporter &BR) const;
+};
+
+static void emitDiagnostics(const BoundNodes &Match, const Decl *D,
+ BugReporter &BR, AnalysisManager &AM,
+ const PointerIterationChecker *Checker) {
+ auto *ADC = AM.getAnalysisDeclContext(D);
+
+ const auto *MarkedStmt = Match.getNodeAs<Stmt>(WarnAtNode);
+ assert(MarkedStmt);
+
+ auto Range = MarkedStmt->getSourceRange();
+ auto Location = PathDiagnosticLocation::createBegin(MarkedStmt,
+ BR.getSourceManager(),
+ ADC);
+ std::string Diagnostics;
+ llvm::raw_string_ostream OS(Diagnostics);
+ OS << "Iteration of pointer-like elements "
+ << "can result in non-deterministic ordering";
+
+ BR.EmitBasicReport(ADC->getDecl(), Checker,
+ "Iteration of pointer-like elements", "Non-determinism",
+ OS.str(), Location, Range);
+}
+
+// Assumption: Iteration of ordered containers of pointers is deterministic.
+
+// TODO: Currently, we only check for std::unordered_set. Other unordered
+// containers like std::unordered_map also need to be handled.
+
+// TODO: Currently, we do not check what the for loop does with the iterated
+// pointer values. Not all iterations may cause non-determinism. For example,
+// counting or summing up the elements should not be non-deterministic.
+
+auto matchUnorderedIterWithPointers() -> decltype(decl()) {
+
+ auto UnorderedContainerM = declRefExpr(to(varDecl(hasType(
+ recordDecl(hasName("std::unordered_set")
+ )))));
+
+ auto PointerTypeM = varDecl(hasType(hasCanonicalType(pointerType())));
+
+ auto PointerIterM = stmt(cxxForRangeStmt(
+ hasLoopVariable(PointerTypeM),
+ hasRangeInit(UnorderedContainerM)
+ )).bind(WarnAtNode);
+
+ return decl(forEachDescendant(PointerIterM));
+}
+
+void PointerIterationChecker::checkASTCodeBody(const Decl *D,
+ AnalysisManager &AM,
+ BugReporter &BR) const {
+ auto MatcherM = matchUnorderedIterWithPointers();
+
+ auto Matches = match(MatcherM, *D, AM.getASTContext());
+ for (const auto &Match : Matches)
+ emitDiagnostics(Match, D, BR, AM, this);
+}
+
+} // end of anonymous namespace
+
+void ento::registerPointerIterationChecker(CheckerManager &Mgr) {
+ Mgr.registerChecker<PointerIterationChecker>();
+}
+
+bool ento::shouldRegisterPointerIterationChecker(const LangOptions &LO) {
+ return LO.CPlusPlus;
+}