new loplugin: inlinesimpleaccessmethods
Create a rewriting plugin for finding methods that simply return object fields, and should therefore be declared in the header, so that the compiler can reduce method calls into a simple fixed-offset load instruction. Change-Id: I7a620fc54250b79681918dc31ed9a8f21118c037 Signed-off-by: Stephan Bergmann <sbergman@redhat.com>
This commit is contained in:
Noel Grandin
committed by
Stephan Bergmann
Stephan Bergmann
parent
866a4436d3
commit
6f2edd4514
282
compilerplugins/clang/inlinesimplememberfunctions.cxx
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282
compilerplugins/clang/inlinesimplememberfunctions.cxx
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@@ -0,0 +1,282 @@
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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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#include <string>
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#include "plugin.hxx"
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// Methods that purely return a local field should be declared in the header and be declared inline.
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// So that the compiler can elide the function call and turn it into a simple fixed-offset-load instruction.
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namespace {
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class InlineSimpleMemberFunctions:
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public RecursiveASTVisitor<InlineSimpleMemberFunctions>, public loplugin::RewritePlugin
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{
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public:
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explicit InlineSimpleMemberFunctions(InstantiationData const & data): RewritePlugin(data) {}
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virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
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bool VisitCXXMethodDecl(const CXXMethodDecl * decl);
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private:
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bool isInUnoIncludeFile(SourceLocation spellingLocation) const;
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bool isInMainFile(SourceLocation spellingLocation) const;
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bool rewrite(const CXXMethodDecl * functionDecl);
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};
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static bool oneAndOnlyOne(clang::Stmt::const_child_range range) {
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if (range.empty()) {
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return false;
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}
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if ((++range.first) != range.second) {
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return false;
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}
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return true;
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}
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bool InlineSimpleMemberFunctions::VisitCXXMethodDecl(const CXXMethodDecl * functionDecl) {
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if (ignoreLocation(functionDecl)) {
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return true;
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}
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// no point in doing virtual methods, the compiler always has to generate a vtable entry and a method
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if (functionDecl->isVirtual()) {
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return true;
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}
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if (functionDecl->getTemplatedKind() != FunctionDecl::TK_NonTemplate) {
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return true;
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}
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if (!functionDecl->isInstance()) {
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return true;
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}
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if (!functionDecl->isOutOfLine()) {
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return true;
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}
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if( !functionDecl->hasBody()) {
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return true;
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}
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if( functionDecl->isInlineSpecified()) {
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return true;
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}
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// ignore stuff that forms part of the stable URE interface
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if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
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functionDecl->getCanonicalDecl()->getNameInfo().getLoc()))) {
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return true;
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}
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// ignore stuff like:
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// template<class E> E * Sequence<E>::begin() { return getArray(); }
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if( functionDecl->getParent()->getDescribedClassTemplate() != nullptr ) {
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return true;
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}
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/*
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The chain here looks like
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CompoundStmt
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ReturnStmt
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other stuff
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CXXThisExpr
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*/
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const CompoundStmt* compoundStmt = dyn_cast< CompoundStmt >( functionDecl->getBody() );
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if (compoundStmt == nullptr) {
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return true;
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}
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if (compoundStmt->body_begin() == compoundStmt->body_end()) {
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return true;
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}
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const Stmt* childStmt = *compoundStmt->child_begin();
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if (dyn_cast<ReturnStmt>( childStmt ) == nullptr) {
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return true;
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}
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if (!oneAndOnlyOne(childStmt->children())) {
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return true;
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}
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/* Don't warn if we see a method definition like
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X X::a() {
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return *this;
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}
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which translates to:
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CompoundStmt
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ReturnStmt
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ImplicitCastExpr
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UnaryOperator
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CXXThisExpr
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or:
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CompoundStmt
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ReturnStmt
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UnaryOperator
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CXXThisExpr
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*/
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childStmt = *childStmt->child_begin();
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if (dyn_cast<ImplicitCastExpr>( childStmt ) != nullptr
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&& oneAndOnlyOne( childStmt->children() ))
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{
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const Stmt* childStmt2 = *childStmt->child_begin();
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if (dyn_cast<UnaryOperator>( childStmt2 ) != nullptr
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&& oneAndOnlyOne(childStmt2->children()))
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{
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childStmt2 = *childStmt2->child_begin();
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if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
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&& childStmt2->children().empty())
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{
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return true;
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}
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}
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}
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if (dyn_cast<UnaryOperator>( childStmt ) != nullptr
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&& oneAndOnlyOne( childStmt->children() ))
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{
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const Stmt* childStmt2 = *childStmt->child_begin();
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if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
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&& childStmt2->children().empty())
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{
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return true;
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}
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}
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/* look for a chain like:
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CompoundStmt
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ReturnStmt
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ImplicitCastExpr
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MemberExpr
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CXXThisExpr
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*/
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if (dyn_cast<ImplicitCastExpr>( childStmt ) != nullptr
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&& oneAndOnlyOne( childStmt->children() ))
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{
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const Stmt* childStmt2 = *childStmt->child_begin();
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if (dyn_cast<MemberExpr>( childStmt2 ) != nullptr
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&& oneAndOnlyOne(childStmt2->children()))
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{
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childStmt2 = *childStmt2->child_begin();
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if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
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&& childStmt2->children().empty())
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{
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if (!rewrite(functionDecl))
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{
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report(
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DiagnosticsEngine::Warning,
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"inlinesimpleaccessmethods",
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functionDecl->getSourceRange().getBegin())
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<< functionDecl->getSourceRange();
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}
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return true;
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}
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}
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}
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return true;
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}
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bool InlineSimpleMemberFunctions::isInUnoIncludeFile(SourceLocation spellingLocation) const {
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StringRef name {
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compiler.getSourceManager().getFilename(spellingLocation) };
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return isInMainFile(spellingLocation)
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? (name == SRCDIR "/cppu/source/cppu/compat.cxx"
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|| name == SRCDIR "/cppuhelper/source/compat.cxx"
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|| name == SRCDIR "/sal/osl/all/compat.cxx")
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: (name.startswith(SRCDIR "/include/com/")
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|| name.startswith(SRCDIR "/include/cppu/")
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|| name.startswith(SRCDIR "/include/cppuhelper/")
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|| name.startswith(SRCDIR "/include/osl/")
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|| name.startswith(SRCDIR "/include/rtl/")
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|| name.startswith(SRCDIR "/include/sal/")
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|| name.startswith(SRCDIR "/include/salhelper/")
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|| name.startswith(SRCDIR "/include/systools/")
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|| name.startswith(SRCDIR "/include/typelib/")
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|| name.startswith(SRCDIR "/include/uno/")
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|| name == SRCDIR "/include/comphelper/implbase_var.hxx");
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}
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bool InlineSimpleMemberFunctions::isInMainFile(SourceLocation spellingLocation) const {
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#if (__clang_major__ == 3 && __clang_minor__ >= 4) || __clang_major__ > 3
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return compiler.getSourceManager().isInMainFile(spellingLocation);
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#else
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return compiler.getSourceManager().isFromMainFile(spellingLocation);
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#endif
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}
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static std::string ReplaceString(std::string subject, const std::string& search,
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const std::string& replace) {
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size_t pos = 0;
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while ((pos = subject.find(search, pos)) != std::string::npos) {
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subject.replace(pos, search.length(), replace);
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pos += replace.length();
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}
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return subject;
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}
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bool InlineSimpleMemberFunctions::rewrite(const CXXMethodDecl * functionDecl) {
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if (rewriter == nullptr) {
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return false;
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}
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// Only rewrite declarations in include files if a
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// definition is also seen, to avoid compilation of a
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// definition (in a main file only processed later) to fail
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// with a "mismatch" error before the rewriter had a chance
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// to act upon the definition.
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if (!isInMainFile(
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compiler.getSourceManager().getSpellingLoc(
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functionDecl->getNameInfo().getLoc()))) {
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return false;
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}
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const char *p1, *p2;
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// get the function body contents
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p1 = compiler.getSourceManager().getCharacterData( functionDecl->getBody()->getLocStart() );
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p2 = compiler.getSourceManager().getCharacterData( functionDecl->getBody()->getLocEnd() );
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std::string s1( p1, p2 - p1 + 1);
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// strip linefeeds and any double-spaces, so we have a max of one space between tokens
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s1 = ReplaceString(s1, "\r", "");
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s1 = ReplaceString(s1, "\n", "");
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s1 = ReplaceString(s1, "\t", " ");
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s1 = ReplaceString(s1, " ", " ");
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s1 = ReplaceString(s1, " ", " ");
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s1 = ReplaceString(s1, " ", " ");
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s1 = " " + s1;
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// scan from the end of the functions body through the whitespace, so we can do a nice clean remove
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// commented out because for some reason it will sometimes chomp an extra token
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// SourceLocation endOfRemoveLoc = functionDecl->getBody()->getLocEnd();
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// for (;;) {
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// endOfRemoveLoc = endOfRemoveLoc.getLocWithOffset(1);
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// p1 = compiler.getSourceManager().getCharacterData( endOfRemoveLoc );
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// if (*p1 != ' ' && *p1 != '\r' && *p1 != '\n' && *p1 != '\t')
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// break;
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// }
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// remove the function's out of line body and declaration
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RewriteOptions opts;
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opts.RemoveLineIfEmpty = true;
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if (!removeText(SourceRange(functionDecl->getLocStart(), functionDecl->getBody()->getLocEnd()), opts)) {
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return false;
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}
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// scan forward until we find the semicolon
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const FunctionDecl * canonicalDecl = functionDecl->getCanonicalDecl();
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p1 = compiler.getSourceManager().getCharacterData( canonicalDecl->getLocEnd() );
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p2 = ++p1;
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while (*p2 != 0 && *p2 != ';') p2++;
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// insert the function body into the inline function definition (i.e. the one inside the class definition)
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return replaceText(canonicalDecl->getLocEnd().getLocWithOffset(p2 - p1 + 1), 1, s1);
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}
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loplugin::Plugin::Registration< InlineSimpleMemberFunctions > X("inlinesimplememberfunctions");
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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