llvm/clang/lib/StaticAnalyzer/Checkers/UnreachableCodeChecker.cpp

//==- UnreachableCodeChecker.cpp - Generalized dead code checker -*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// This file implements a generalized unreachable code checker using a
// path-sensitive analysis. We mark any path visited, and then walk the CFG as a
// post-analysis to determine what was never visited.
//
// A similar flow-sensitive only check exists in Analysis/ReachableCode.cpp
//===----------------------------------------------------------------------===//

#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/AST/ParentMap.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/SourceManager.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerHelpers.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
#include "llvm/ADT/SmallSet.h"
#include <optional>

usingnamespaceclang;
usingnamespaceento;

namespace {
class UnreachableCodeChecker : public Checker<check::EndAnalysis> { … };
}

void UnreachableCodeChecker::checkEndAnalysis(ExplodedGraph &G,
                                              BugReporter &B,
                                              ExprEngine &Eng) const { … }

// Recursively finds the entry point(s) for this dead CFGBlock.
void UnreachableCodeChecker::FindUnreachableEntryPoints(const CFGBlock *CB,
                                                        CFGBlocksSet &reachable,
                                                        CFGBlocksSet &visited) { … }

// Find the Stmt* in a CFGBlock for reporting a warning
const Stmt *UnreachableCodeChecker::getUnreachableStmt(const CFGBlock *CB) { … }

// Determines if the path to this CFGBlock contained an element that infers this
// block is a false positive. We assume that FindUnreachableEntryPoints has
// already marked only the entry points to any dead code, so we need only to
// find the condition that led to this block (the predecessor of this block.)
// There will never be more than one predecessor.
bool UnreachableCodeChecker::isInvalidPath(const CFGBlock *CB,
                                           const ParentMap &PM) { … }

// Returns true if the given CFGBlock is empty
bool UnreachableCodeChecker::isEmptyCFGBlock(const CFGBlock *CB) { … }

void ento::registerUnreachableCodeChecker(CheckerManager &mgr) { … }

bool ento::shouldRegisterUnreachableCodeChecker(const CheckerManager &mgr) { … }