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office-gobmx/compilerplugins/clang/unnecessarylocking.cxx
Noel Grandin f2c02331a7 new loplugin:unnecessary locking 
off by default, since each warning needs careful inspection

Change-Id: I805c1d1cdde531a1afdc76e87b22f879fc3c9753
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/134641
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
2022-05-20 08:03:27 +02:00

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
#include <cassert>
#include <string>
#include <iostream>
#include <fstream>
#include <set>
#include <unordered_set>
#include <clang/AST/CXXInheritance.h>
#include "config_clang.h"
#include "plugin.hxx"
#include "check.hxx"
/**
Look for methods that are taking a lock at the top of the method, but then not
touching any object-local state. In which case the method might not need locking.
TODO
(*) check if the data being returned is never modified, in which case locking is not necessary
*/
namespace
{
class UnnecessaryLocking : public loplugin::FilteringPlugin<UnnecessaryLocking>
{
public:
explicit UnnecessaryLocking(loplugin::InstantiationData const& data)
: FilteringPlugin(data)
{
}
virtual bool preRun() override
{
// StringRef fn(handler.getMainFileName());
// if (loplugin::isSamePathname(fn, WORKDIR "/YaccTarget/unoidl/source/sourceprovider-parser.cxx"))
// return false;
return true;
}
virtual void run() override
{
if (preRun())
TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
}
bool TraverseCXXMethodDecl(CXXMethodDecl*);
bool VisitCXXThisExpr(const CXXThisExpr*);
private:
bool isSolarMutexLockGuardStmt(const Stmt*);
const Stmt* isOtherMutexLockGuardStmt(const Stmt*);
std::vector<bool> m_TouchesThis;
// so we ignore the CxxThisEpxr that references the maMutex in the guard expression
std::vector<const Stmt*> m_IgnoreThis;
};
bool UnnecessaryLocking::TraverseCXXMethodDecl(CXXMethodDecl* cxxMethodDecl)
{
if (ignoreLocation(cxxMethodDecl))
return true;
if (!cxxMethodDecl->isInstance())
return true;
if (!cxxMethodDecl->isThisDeclarationADefinition())
return true;
auto compoundStmt = dyn_cast_or_null<CompoundStmt>(cxxMethodDecl->getBody());
if (!compoundStmt || compoundStmt->size() < 1)
return true;
const Stmt* firstStmt = *compoundStmt->body_begin();
bool solarMutex = isSolarMutexLockGuardStmt(firstStmt);
const Stmt* ignoreThisStmt = nullptr;
if (!solarMutex)
ignoreThisStmt = isOtherMutexLockGuardStmt(firstStmt);
if (!solarMutex && ignoreThisStmt == nullptr)
return true;
m_TouchesThis.push_back(false);
m_IgnoreThis.push_back(ignoreThisStmt);
bool rv = FilteringPlugin::TraverseCXXMethodDecl(cxxMethodDecl);
if (!m_TouchesThis.back())
{
StringRef fn = getFilenameOfLocation(
compiler.getSourceManager().getSpellingLoc(cxxMethodDecl->getBeginLoc()));
if (
// template magic
!loplugin::isSamePathname(fn, SRCDIR "/include/comphelper/unique_disposing_ptr.hxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/inc/unobaseclass.hxx")
// toolkit needs to lock around access to static methods in vcl
&& !loplugin::isSamePathname(fn, SRCDIR "/toolkit/source/awt/vclxtoolkit.cxx")
&& !loplugin::isSamePathname(fn,
SRCDIR "/toolkit/source/controls/tree/treecontrolpeer.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/toolkit/source/awt/vclxcontainer.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/toolkit/source/awt/vclxdevice.cxx")
// touching shared global data
&& !loplugin::isSamePathname(fn, SRCDIR
"/framework/source/fwi/classes/protocolhandlercache.cxx")
// lock around access to static methods in vcl
&& !loplugin::isSamePathname(fn, SRCDIR "/framework/source/services/taskcreatorsrv.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/svx/source/dialog/SafeModeUI.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR
"/svx/source/accessibility/AccessibleFrameSelector.cxx")
// not sure
&& !loplugin::isSamePathname(fn, SRCDIR "/sfx2/source/dialog/filedlghelper.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sfx2/source/appl/appdispatchprovider.cxx")
// touching shared global data
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unoftn.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unolinebreak.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unoobj.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unorefmk.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unotbl.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/filter/xml/xmltexti.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/uibase/uno/dlelstnr.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/access/accdoc.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/access/acccontext.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unocontentcontrol.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sw/source/core/unocore/unobkm.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sc/source/ui/unoobj/docuno.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sc/source/ui/unoobj/afmtuno.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/sc/source/ui/unoobj/appluno.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/unoxml/source/dom/documentbuilder.cxx")
&& !loplugin::isSamePathname(
fn, SRCDIR "/sd/source/ui/accessibility/AccessibleDrawDocumentView.cxx")
&& !loplugin::isSamePathname(fn, SRCDIR "/starmath/source/accessibility.cxx")
&& !loplugin::isSamePathname(fn,
SRCDIR "/starmath/source/AccessibleSmElementsControl.cxx"))
{
report(DiagnosticsEngine::Warning, "unnecessary locking", cxxMethodDecl->getBeginLoc())
<< cxxMethodDecl->getSourceRange();
}
}
m_TouchesThis.pop_back();
m_IgnoreThis.pop_back();
return rv;
}
bool UnnecessaryLocking::isSolarMutexLockGuardStmt(const Stmt* stmt)
{
auto declStmt = dyn_cast<DeclStmt>(stmt);
if (!declStmt)
return false;
if (!declStmt->isSingleDecl())
return false;
auto varDecl = dyn_cast<VarDecl>(declStmt->getSingleDecl());
if (!varDecl)
return false;
auto tc = loplugin::TypeCheck(varDecl->getType());
if (!tc.Class("SolarMutexGuard").GlobalNamespace()
&& !tc.Class("SolarMutexClearableGuard").GlobalNamespace()
&& !tc.Class("SolarMutexResettableGuard").GlobalNamespace()
&& !tc.Class("SolarMutexTryAndBuyGuard").GlobalNamespace())
return false;
return true;
}
const Stmt* UnnecessaryLocking::isOtherMutexLockGuardStmt(const Stmt* stmt)
{
auto declStmt = dyn_cast<DeclStmt>(stmt);
if (!declStmt)
return nullptr;
if (!declStmt->isSingleDecl())
return nullptr;
auto varDecl = dyn_cast<VarDecl>(declStmt->getSingleDecl());
if (!varDecl)
return nullptr;
auto tc = loplugin::TypeCheck(varDecl->getType());
if (!tc.Class("unique_lock").StdNamespace() && !tc.Class("scoped_lock").StdNamespace())
return nullptr;
auto cxxConstructExpr = dyn_cast<CXXConstructExpr>(varDecl->getInit());
if (!cxxConstructExpr || cxxConstructExpr->getNumArgs() < 1)
return nullptr;
auto memberExpr = dyn_cast<MemberExpr>(cxxConstructExpr->getArg(0));
if (!memberExpr)
return nullptr;
auto thisStmt = memberExpr->getBase();
return thisStmt;
}
bool UnnecessaryLocking::VisitCXXThisExpr(const CXXThisExpr* cxxThisExpr)
{
if (ignoreLocation(cxxThisExpr))
return true;
// just in case
if (m_TouchesThis.empty())
return true;
// already found something
if (m_TouchesThis.back())
return true;
if (m_IgnoreThis.back() && m_IgnoreThis.back() == cxxThisExpr)
return true;
m_TouchesThis.back() = true;
return true;
}
/** off by default because each warning needs to be carefully inspected */
loplugin::Plugin::Registration<UnnecessaryLocking> unnecessarylocking("unnecessarylocking", false);
}
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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