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 
14 namespace clang {
15 namespace dataflow {
16 
17 /// Determines whether `D` is one of the methods used to implement Chromium's
18 /// `CHECK` macros. Populates `CheckDecls`, if empty.
19 bool 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().endswith("Check"))
47         CheckDecls.insert(M);
48   }
49 
50   return CheckDecls.contains(&D);
51 }
52 
53 bool ChromiumCheckModel::transfer(const Stmt *Stmt, Environment &Env) {
54   if (const auto *Call = dyn_cast<CallExpr>(Stmt)) {
55     if (const auto *M = dyn_cast<CXXMethodDecl>(Call->getDirectCallee())) {
56       if (isCheckLikeMethod(CheckDecls, *M)) {
57         // Mark this branch as unreachable.
58         Env.addToFlowCondition(Env.getBoolLiteralValue(false));
59         return true;
60       }
61     }
62   }
63   return false;
64 }
65 
66 } // namespace dataflow
67 } // namespace clang
68