1//===-- ChromiumCheckModel.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#include "clang/Analysis/FlowSensitive/Models/ChromiumCheckModel.h"
10#include "clang/AST/Decl.h"
11#include "clang/AST/DeclCXX.h"
12#include "llvm/ADT/DenseSet.h"
13
14namespace clang {
15namespace dataflow {
16
17/// Determines whether `D` is one of the methods used to implement Chromium's
18/// `CHECK` macros. Populates `CheckDecls`, if empty.
19bool isCheckLikeMethod(llvm::SmallDenseSet<const CXXMethodDecl *> &CheckDecls,
20                       const CXXMethodDecl &D) {
21  // All of the methods of interest are static, so avoid any lookup for
22  // non-static methods (the common case).
23  if (!D.isStatic())
24    return false;
25
26  if (CheckDecls.empty()) {
27    // Attempt to initialize `CheckDecls` with the methods in class
28    // `CheckError`.
29    const CXXRecordDecl *ParentClass = D.getParent();
30    if (ParentClass == nullptr || !ParentClass->getDeclName().isIdentifier() ||
31        ParentClass->getName() != "CheckError")
32      return false;
33
34    // Check whether namespace is "logging".
35    const auto *N =
36        dyn_cast_or_null<NamespaceDecl>(ParentClass->getDeclContext());
37    if (N == nullptr || !N->getDeclName().isIdentifier() ||
38        N->getName() != "logging")
39      return false;
40
41    // Check whether "logging" is a top-level namespace.
42    if (N->getParent() == nullptr || !N->getParent()->isTranslationUnit())
43      return false;
44
45    for (const CXXMethodDecl *M : ParentClass->methods())
46      if (M->getDeclName().isIdentifier() && M->getName().ends_with("Check"))
47        CheckDecls.insert(M);
48  }
49
50  return CheckDecls.contains(&D);
51}
52
53bool ChromiumCheckModel::transfer(const CFGElement &Element, Environment &Env) {
54  auto CS = Element.getAs<CFGStmt>();
55  if (!CS)
56    return false;
57  auto Stmt = CS->getStmt();
58  if (const auto *Call = dyn_cast<CallExpr>(Stmt)) {
59    if (const auto *M = dyn_cast<CXXMethodDecl>(Call->getDirectCallee())) {
60      if (isCheckLikeMethod(CheckDecls, *M)) {
61        // Mark this branch as unreachable.
62        Env.assume(Env.arena().makeLiteral(false));
63        return true;
64      }
65    }
66  }
67  return false;
68}
69
70} // namespace dataflow
71} // namespace clang
72