compilerplugins/clang/inlinesimplememberfunctions.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9
  10 #include <string>
  11
  12 #include "plugin.hxx"
  13 #include "compat.hxx"
  14
  15 // Methods that purely return a local field should be declared in the header and be declared inline.
  16 // So that the compiler can elide the function call and turn it into a simple fixed-offset-load instruction.
  17
  18 namespace {
  19
  20 class InlineSimpleMemberFunctions:
  21     public RecursiveASTVisitor<InlineSimpleMemberFunctions>, public loplugin::RewritePlugin
  22 {
  23 public:
  24     explicit InlineSimpleMemberFunctions(InstantiationData const & data): RewritePlugin(data) {}
  25
  26     virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
  27
  28     bool VisitCXXMethodDecl(const CXXMethodDecl * decl);
  29 private:
  30     bool rewrite(const CXXMethodDecl * functionDecl);
  31 };
  32
  33 static bool oneAndOnlyOne(clang::Stmt::const_child_range range) {
  34     if (range.empty()) {
  35         return false;
  36     }
  37     if ((++range.first) != range.second) {
  38         return false;
  39     }
  40     return true;
  41 }
  42
  43
  44 bool InlineSimpleMemberFunctions::VisitCXXMethodDecl(const CXXMethodDecl * functionDecl) {
  45     if (ignoreLocation(functionDecl)) {
  46         return true;
  47     }
  48     // no point in doing virtual methods, the compiler always has to generate a vtable entry and a method
  49     if (functionDecl->isVirtual()) {
  50         return true;
  51     }
  52     if (functionDecl->getTemplatedKind() != FunctionDecl::TK_NonTemplate) {
  53         return true;
  54     }
  55     if (!functionDecl->isInstance()) {
  56         return true;
  57     }
  58     if (!functionDecl->isOutOfLine()) {
  59         return true;
  60     }
  61     if( !functionDecl->hasBody()) {
  62         return true;
  63     }
  64     if( functionDecl->isInlineSpecified()) {
  65         return true;
  66     }
  67     if( functionDecl->getCanonicalDecl()->isInlineSpecified()) {
  68         return true;
  69     }
  70     if( functionDecl->getNameAsString().find("Impl") != std::string::npos) {
  71         return true;
  72     }
  73     // ignore stuff that forms part of the stable URE interface
  74     if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
  75                               functionDecl->getCanonicalDecl()->getNameInfo().getLoc()))) {
  76         return true;
  77     }
  78     // ignore stuff like:
  79     //   template<class E> E * Sequence<E>::begin() { return getArray(); }
  80     if( functionDecl->getParent()->getDescribedClassTemplate() != nullptr ) {
  81         return true;
  82     }
  83
  84     /*
  85       The chain here looks like
  86         CompoundStmt
  87           ReturnStmt
  88             other stuff
  89               CXXThisExpr
  90     */
  91
  92     const CompoundStmt* compoundStmt = dyn_cast< CompoundStmt >( functionDecl->getBody() );
  93     if (compoundStmt == nullptr) {
  94         return true;
  95     }
  96     if (compoundStmt->body_begin() == compoundStmt->body_end()) {
  97         return true;
  98     }
  99
 100
 101     const Stmt* childStmt = *compoundStmt->child_begin();
 102
 103     if (dyn_cast<ReturnStmt>( childStmt ) == nullptr) {
 104         return true;
 105     }
 106     if (!oneAndOnlyOne(childStmt->children())) {
 107         return true;
 108     }
 109
 110
 111     /* Don't warn if we see a method definition like
 112          X X::a() {
 113              return *this;
 114          }
 115       which translates to:
 116         CompoundStmt
 117           ReturnStmt
 118             ImplicitCastExpr
 119               UnaryOperator
 120                 CXXThisExpr
 121       or:
 122         CompoundStmt
 123           ReturnStmt
 124             UnaryOperator
 125               CXXThisExpr
 126     */
 127     childStmt = *childStmt->child_begin();
 128     if (dyn_cast<ImplicitCastExpr>( childStmt ) != nullptr
 129         && oneAndOnlyOne( childStmt->children() ))
 130     {
 131         const Stmt* childStmt2 = *childStmt->child_begin();
 132         if (dyn_cast<UnaryOperator>( childStmt2 ) != nullptr
 133             && oneAndOnlyOne(childStmt2->children()))
 134         {
 135             childStmt2 = *childStmt2->child_begin();
 136             if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
 137                 && childStmt2->children().empty())
 138             {
 139                 return true;
 140             }
 141         }
 142     }
 143     if (dyn_cast<UnaryOperator>( childStmt ) != nullptr
 144         && oneAndOnlyOne( childStmt->children() ))
 145     {
 146         const Stmt* childStmt2 = *childStmt->child_begin();
 147         if (dyn_cast<CXXThisExpr>( childStmt2 ) != nullptr
 148             && childStmt2->children().empty())
 149         {
 150             return true;
 151         }
 152     }
 153
 154     /* look for a chains like:
 155        CompoundStmt
 156          ReturnStmt
 157            stuff
 158              CXXThisExpr
 159     */
 160     childStmt = *(*compoundStmt->child_begin())->child_begin();
 161     while (1) {
 162         if (dyn_cast<CallExpr>( childStmt ) != nullptr)
 163             return true;
 164         if (dyn_cast<CXXNewExpr>( childStmt ) != nullptr)
 165             return true;
 166         if (dyn_cast<CXXConstructExpr>( childStmt ) != nullptr)
 167             return true;
 168         if (dyn_cast<ConditionalOperator>( childStmt ) != nullptr)
 169             return true;
 170         if (dyn_cast<BinaryOperator>( childStmt ) != nullptr)
 171             return true;
 172         // exclude methods that return fields on incomplete types .e.g the pImpl pattern
 173         const MemberExpr* memberExpr = dyn_cast<MemberExpr>( childStmt );
 174         if (memberExpr != nullptr && memberExpr->getMemberDecl()) {
 175             const FieldDecl* fieldDecl = dyn_cast<FieldDecl>(memberExpr->getMemberDecl());
 176             if (fieldDecl != nullptr)
 177             {
 178                 // yes, a little bit of a hack. However, it is quite hard to determine if the method
 179                 // in question is accessing a field via a pImpl pattern.
 180                 if (fieldDecl->getType()->isIncompleteType())
 181                     return true;
 182                 if (fieldDecl->getNameAsString().find("Impl") != std::string::npos)
 183                     return true;
 184                 if (fieldDecl->getNameAsString().find("pImp") != std::string::npos)
 185                     return true;
 186                 // somewhere in VCL
 187                 if (fieldDecl->getNameAsString().find("mpGlobalSyncData") != std::string::npos)
 188                     return true;
 189                 std::string s = fieldDecl->getType().getAsString();
 190                 if (s.find("Impl") != std::string::npos || s.find("pImp") != std::string::npos || s.find("Internal") != std::string::npos)
 191                     return true;
 192             }
 193         }
 194         if (dyn_cast<CXXThisExpr>( childStmt ) != nullptr) {
 195             if (!rewrite(functionDecl))
 196             {
 197                 report(
 198                     DiagnosticsEngine::Warning,
 199                     "inlinesimpleaccessmethods",
 200                     functionDecl->getSourceRange().getBegin())
 201                   << functionDecl->getSourceRange();
 202                 // display the location of the class member declaration so I don't have to search for it by hand
 203                 report(
 204                     DiagnosticsEngine::Note,
 205                     "inlinesimpleaccessmethods",
 206                     functionDecl->getCanonicalDecl()->getSourceRange().getBegin())
 207                   << functionDecl->getCanonicalDecl()->getSourceRange();
 208                 }
 209              return true;
 210         }
 211         if ( childStmt->children().empty() )
 212             return true;
 213         childStmt = *childStmt->child_begin();
 214     }
 215     return true;
 216 }
 217
 218 static std::string ReplaceString(std::string subject, const std::string& search,
 219                           const std::string& replace) {
 220     size_t pos = 0;
 221     while ((pos = subject.find(search, pos)) != std::string::npos) {
 222          subject.replace(pos, search.length(), replace);
 223          pos += replace.length();
 224     }
 225     return subject;
 226 }
 227
 228 bool InlineSimpleMemberFunctions::rewrite(const CXXMethodDecl * functionDecl) {
 229     if (rewriter == nullptr) {
 230         return false;
 231     }
 232     // Only rewrite declarations in include files if a
 233     // definition is also seen, to avoid compilation of a
 234     // definition (in a main file only processed later) to fail
 235     // with a "mismatch" error before the rewriter had a chance
 236     // to act upon the definition.
 237     if (!compat::isInMainFile( compiler.getSourceManager(),
 238                compiler.getSourceManager().getSpellingLoc(
 239                    functionDecl->getNameInfo().getLoc()))) {
 240         return false;
 241     }
 242
 243     const char *p1, *p2;
 244
 245     // get the function body contents
 246     p1 = compiler.getSourceManager().getCharacterData( functionDecl->getBody()->getLocStart() );
 247     p2 = compiler.getSourceManager().getCharacterData( functionDecl->getBody()->getLocEnd() );
 248     std::string s1( p1, p2 - p1 + 1);
 249
 250     /* we can't safely move around stuff containing comments, we mess up the resulting code */
 251     if ( s1.find("/*") != std::string::npos || s1.find("//") != std::string::npos ) {
 252         return false;
 253     }
 254
 255     // strip linefeeds and any double-spaces, so we have a max of one space between tokens
 256     s1 = ReplaceString(s1, "\r", "");
 257     s1 = ReplaceString(s1, "\n", "");
 258     s1 = ReplaceString(s1, "\t", " ");
 259     s1 = ReplaceString(s1, "  ", " ");
 260     s1 = ReplaceString(s1, "  ", " ");
 261     s1 = ReplaceString(s1, "  ", " ");
 262     s1 = " " + s1;
 263
 264     // scan from the end of the function's body through the trailing whitespace, so we can do a nice clean remove
 265 // commented out because for some reason it will sometimes chomp an extra token
 266 //    SourceLocation endOfRemoveLoc = functionDecl->getBody()->getLocEnd();
 267 //    for (;;) {
 268 //        endOfRemoveLoc = endOfRemoveLoc.getLocWithOffset(1);
 269 //        p1 = compiler.getSourceManager().getCharacterData( endOfRemoveLoc );
 270 //        if (*p1 != ' ' && *p1 != '\r' && *p1 != '\n' && *p1 != '\t')
 271 //            break;
 272 //    }
 273
 274     // remove the function's out of line body and declaration
 275     RewriteOptions opts;
 276     opts.RemoveLineIfEmpty = true;
 277     if (!removeText(SourceRange(functionDecl->getLocStart(), functionDecl->getBody()->getLocEnd()), opts)) {
 278         return false;
 279     }
 280
 281     // scan forward until we find the semicolon
 282     const FunctionDecl * canonicalDecl = functionDecl->getCanonicalDecl();
 283     p1 = compiler.getSourceManager().getCharacterData( canonicalDecl->getLocEnd() );
 284     p2 = ++p1;
 285     while (*p2 != 0 && *p2 != ';') p2++;
 286
 287     // insert the function body into the inline function definition (i.e. the one inside the class definition)
 288     return replaceText(canonicalDecl->getLocEnd().getLocWithOffset(p2 - p1 + 1), 1, s1);
 289 }
 290
 291 loplugin::Plugin::Registration< InlineSimpleMemberFunctions > X("inlinesimplememberfunctions");
 292
 293 }
 294
 295 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */