1//== PointerIterationChecker.cpp ------------------------------- -*- C++ -*--=//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines PointerIterationChecker which checks for non-determinism
10// caused due to iteration of unordered containers of pointer elements.
11//
12//===----------------------------------------------------------------------===//
13
14#include "clang/ASTMatchers/ASTMatchFinder.h"
15#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
16#include "clang/StaticAnalyzer/Core/Checker.h"
17#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
18
19using namespace clang;
20using namespace ento;
21using namespace ast_matchers;
22
23namespace {
24
25// ID of a node at which the diagnostic would be emitted.
26constexpr llvm::StringLiteral WarnAtNode = "iter";
27
28class PointerIterationChecker : public Checker<check::ASTCodeBody> {
29public:
30 void checkASTCodeBody(const Decl *D,
31 AnalysisManager &AM,
32 BugReporter &BR) const;
33};
34
35static void emitDiagnostics(const BoundNodes &Match, const Decl *D,
36 BugReporter &BR, AnalysisManager &AM,
37 const PointerIterationChecker *Checker) {
38 auto *ADC = AM.getAnalysisDeclContext(D);
39
40 const auto *MarkedStmt = Match.getNodeAs<Stmt>(ID: WarnAtNode);
41 assert(MarkedStmt);
42
43 auto Range = MarkedStmt->getSourceRange();
44 auto Location = PathDiagnosticLocation::createBegin(S: MarkedStmt,
45 SM: BR.getSourceManager(),
46 LAC: ADC);
47 std::string Diagnostics;
48 llvm::raw_string_ostream OS(Diagnostics);
49 OS << "Iteration of pointer-like elements "
50 << "can result in non-deterministic ordering";
51
52 BR.EmitBasicReport(DeclWithIssue: ADC->getDecl(), Checker,
53 BugName: "Iteration of pointer-like elements", BugCategory: "Non-determinism",
54 BugStr: OS.str(), Loc: Location, Ranges: Range);
55}
56
57// Assumption: Iteration of ordered containers of pointers is deterministic.
58
59// TODO: Currently, we only check for std::unordered_set. Other unordered
60// containers like std::unordered_map also need to be handled.
61
62// TODO: Currently, we do not check what the for loop does with the iterated
63// pointer values. Not all iterations may cause non-determinism. For example,
64// counting or summing up the elements should not be non-deterministic.
65
66auto matchUnorderedIterWithPointers() -> decltype(decl()) {
67
68 auto UnorderedContainerM = declRefExpr(to(InnerMatcher: varDecl(hasType(
69 InnerMatcher: recordDecl(hasName(Name: "std::unordered_set")
70 )))));
71
72 auto PointerTypeM = varDecl(hasType(InnerMatcher: hasCanonicalType(InnerMatcher: pointerType())));
73
74 auto PointerIterM = stmt(cxxForRangeStmt(
75 hasLoopVariable(InnerMatcher: PointerTypeM),
76 hasRangeInit(InnerMatcher: UnorderedContainerM)
77 )).bind(ID: WarnAtNode);
78
79 return decl(forEachDescendant(PointerIterM));
80}
81
82void PointerIterationChecker::checkASTCodeBody(const Decl *D,
83 AnalysisManager &AM,
84 BugReporter &BR) const {
85 auto MatcherM = matchUnorderedIterWithPointers();
86
87 auto Matches = match(Matcher: MatcherM, Node: *D, Context&: AM.getASTContext());
88 for (const auto &Match : Matches)
89 emitDiagnostics(Match, D, BR, AM, Checker: this);
90}
91
92} // end of anonymous namespace
93
94void ento::registerPointerIterationChecker(CheckerManager &Mgr) {
95 Mgr.registerChecker<PointerIterationChecker>();
96}
97
98bool ento::shouldRegisterPointerIterationChecker(const CheckerManager &mgr) {
99 const LangOptions &LO = mgr.getLangOpts();
100 return LO.CPlusPlus;
101}
102