Coverage Report

Created: 2020-09-22 08:39

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