clang/lib/Analysis/FlowSensitive/Models/ChromiumCheckModel.cpp

   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 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