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-rw-r--r--compilerplugins/clang/unnecessarylocking.cxx215
1 files changed, 215 insertions, 0 deletions
diff --git a/compilerplugins/clang/unnecessarylocking.cxx b/compilerplugins/clang/unnecessarylocking.cxx
new file mode 100644
index 000000000..c00758b81
--- /dev/null
+++ b/compilerplugins/clang/unnecessarylocking.cxx
@@ -0,0 +1,215 @@
+/* -*- 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: */
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-08 17:56:45 +0000