compilerplugins/clang/constfieldsrewrite.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 #if !defined _WIN32 //TODO, #include <sys/mman.h>
  11
  12 #include <cassert>
  13 #include <string>
  14 #include <iostream>
  15 #include "plugin.hxx"
  16 #include "check.hxx"
  17 #include <sys/mman.h>
  18 #include <sys/types.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <sys/stat.h>
  22 #include <assert.h>
  23 #include <cstring>
  24
  25 /**
  26   This is intended to be run as the second stage of the "constfields" clang plugin.
  27 */
  28
  29 namespace
  30 {
  31 class ConstFieldsRewrite : public RecursiveASTVisitor<ConstFieldsRewrite>,
  32                            public loplugin::RewritePlugin
  33 {
  34 public:
  35     explicit ConstFieldsRewrite(loplugin::InstantiationData const& data);
  36     ~ConstFieldsRewrite();
  37
  38     virtual void run() override
  39     {
  40         if (rewriter)
  41         {
  42             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  43         }
  44     }
  45
  46     bool VisitFieldDecl(const FieldDecl* var);
  47
  48 private:
  49     // I use a brute-force approach - mmap the results file and do a linear search on it
  50     // It works surprisingly well, because the file is small enough to fit into L2 cache on modern CPU's
  51     size_t mmapFilesize;
  52     int mmapFD;
  53     char* mmappedData;
  54 };
  55
  56 size_t getFilesize(const char* filename)
  57 {
  58     struct stat st;
  59     stat(filename, &st);
  60     return st.st_size;
  61 }
  62
  63 ConstFieldsRewrite::ConstFieldsRewrite(loplugin::InstantiationData const& data)
  64     : RewritePlugin(data)
  65 {
  66     static const char sInputFile[] = SRCDIR "/compilerplugins/clang/constfields.results";
  67     mmapFilesize = getFilesize(sInputFile);
  68     //Open file
  69     mmapFD = open(sInputFile, O_RDONLY, 0);
  70     assert(mmapFD != -1);
  71     //Execute mmap
  72     mmappedData = static_cast<char*>(mmap(NULL, mmapFilesize, PROT_READ, MAP_PRIVATE, mmapFD, 0));
  73     assert(mmappedData != NULL);
  74 }
  75
  76 ConstFieldsRewrite::~ConstFieldsRewrite()
  77 {
  78     //Cleanup
  79     int rc = munmap(mmappedData, mmapFilesize);
  80     assert(rc == 0);
  81     close(mmapFD);
  82 }
  83
  84 bool ConstFieldsRewrite::VisitFieldDecl(const FieldDecl* fieldDecl)
  85 {
  86     if (ignoreLocation(fieldDecl))
  87         return true;
  88     // ignore stuff that forms part of the stable URE interface
  89     if (isInUnoIncludeFile(compiler.getSourceManager().getSpellingLoc(
  90             fieldDecl->getCanonicalDecl()->getLocation())))
  91         return true;
  92     // in case we've already processed this field
  93     if (fieldDecl->getType().isConstQualified())
  94         return true;
  95     // in case we've already processed this field
  96     if (fieldDecl->getType().isConstQualified())
  97         return true;
  98     // TODO rewriting T& is a bit trickier
  99     if (loplugin::TypeCheck(fieldDecl->getType()).LvalueReference())
 100         return true;
 101
 102     const RecordDecl* recordDecl = fieldDecl->getParent();
 103     std::string parentClassName;
 104     if (const CXXRecordDecl* cxxRecordDecl = dyn_cast<CXXRecordDecl>(recordDecl))
 105     {
 106         if (cxxRecordDecl->getTemplateInstantiationPattern())
 107             cxxRecordDecl = cxxRecordDecl->getTemplateInstantiationPattern();
 108         parentClassName = cxxRecordDecl->getQualifiedNameAsString();
 109     }
 110     else
 111     {
 112         parentClassName = recordDecl->getQualifiedNameAsString();
 113     }
 114     // the extra spaces match the formatting in the results file, and help avoid false+
 115     std::string aNiceName = "    " + parentClassName + " " + fieldDecl->getNameAsString() + " "
 116                             + fieldDecl->getType().getAsString() + "\n";
 117
 118     // search mmap'ed file for field
 119     const char* aNiceNameStr = aNiceName.c_str();
 120     char* found = std::search(mmappedData, mmappedData + mmapFilesize, aNiceNameStr,
 121                               aNiceNameStr + aNiceName.size());
 122     if (!(found < mmappedData + mmapFilesize))
 123         return true;
 124
 125     SourceManager& SM = compiler.getSourceManager();
 126     auto endLoc = fieldDecl->getTypeSourceInfo()->getTypeLoc().getEndLoc();
 127     endLoc = endLoc.getLocWithOffset(Lexer::MeasureTokenLength(endLoc, SM, compiler.getLangOpts()));
 128
 129     // Calculate how much space is available after the type declaration that we can use to
 130     // overwrite with the " const". This reduces the amount of formatting fixups I need to do.
 131     char const* p1 = SM.getCharacterData(endLoc);
 132     bool success = false;
 133     if (*p1 != ' ')
 134     {
 135         // Sometimes there is no space at all e.g. in
 136         //     FastTokenHandlerBase *mpTokenHandler;
 137         // between the "*" and the "mpTokenHandler", so add an extra space.
 138         success = insertText(endLoc, " const ");
 139     }
 140     else
 141     {
 142         int spaceAvailable = 1;
 143         ++p1;
 144         for (; spaceAvailable < 6; ++spaceAvailable)
 145         {
 146             if (*p1 != ' ')
 147                 break;
 148             ++p1;
 149         }
 150         if (spaceAvailable < 6)
 151             success = replaceText(endLoc, spaceAvailable - 1, " const");
 152         else
 153             success = replaceText(endLoc, spaceAvailable, " const");
 154     }
 155
 156     if (!success)
 157     {
 158         report(DiagnosticsEngine::Warning, "Could not mark field as const",
 159                compat::getBeginLoc(fieldDecl))
 160             << fieldDecl->getSourceRange();
 161     }
 162     return true;
 163 }
 164
 165 loplugin::Plugin::Registration<ConstFieldsRewrite> X("constfieldsrewrite", false);
 166 }
 167
 168 #endif
 169
 170 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */