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      1 //===--- DependencyFile.cpp - Generate dependency file --------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This code generates dependency files.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "clang/Frontend/Utils.h"
     15 #include "clang/Basic/FileManager.h"
     16 #include "clang/Basic/SourceManager.h"
     17 #include "clang/Frontend/DependencyOutputOptions.h"
     18 #include "clang/Frontend/FrontendDiagnostic.h"
     19 #include "clang/Lex/DirectoryLookup.h"
     20 #include "clang/Lex/LexDiagnostic.h"
     21 #include "clang/Lex/PPCallbacks.h"
     22 #include "clang/Lex/Preprocessor.h"
     23 #include "llvm/ADT/StringSet.h"
     24 #include "llvm/Support/FileSystem.h"
     25 #include "llvm/Support/Path.h"
     26 #include "llvm/Support/raw_ostream.h"
     27 
     28 using namespace clang;
     29 
     30 namespace {
     31 class DependencyFileCallback : public PPCallbacks {
     32   std::vector<std::string> Files;
     33   llvm::StringSet<> FilesSet;
     34   const Preprocessor *PP;
     35   std::string OutputFile;
     36   std::vector<std::string> Targets;
     37   bool IncludeSystemHeaders;
     38   bool PhonyTarget;
     39   bool AddMissingHeaderDeps;
     40   bool SeenMissingHeader;
     41 private:
     42   bool FileMatchesDepCriteria(const char *Filename,
     43                               SrcMgr::CharacteristicKind FileType);
     44   void AddFilename(StringRef Filename);
     45   void OutputDependencyFile();
     46 
     47 public:
     48   DependencyFileCallback(const Preprocessor *_PP,
     49                          const DependencyOutputOptions &Opts)
     50     : PP(_PP), OutputFile(Opts.OutputFile), Targets(Opts.Targets),
     51       IncludeSystemHeaders(Opts.IncludeSystemHeaders),
     52       PhonyTarget(Opts.UsePhonyTargets),
     53       AddMissingHeaderDeps(Opts.AddMissingHeaderDeps),
     54       SeenMissingHeader(false) {}
     55 
     56   virtual void FileChanged(SourceLocation Loc, FileChangeReason Reason,
     57                            SrcMgr::CharacteristicKind FileType,
     58                            FileID PrevFID);
     59   virtual void InclusionDirective(SourceLocation HashLoc,
     60                                   const Token &IncludeTok,
     61                                   StringRef FileName,
     62                                   bool IsAngled,
     63                                   CharSourceRange FilenameRange,
     64                                   const FileEntry *File,
     65                                   StringRef SearchPath,
     66                                   StringRef RelativePath,
     67                                   const Module *Imported);
     68 
     69   virtual void EndOfMainFile() {
     70     OutputDependencyFile();
     71   }
     72 };
     73 }
     74 
     75 void clang::AttachDependencyFileGen(Preprocessor &PP,
     76                                     const DependencyOutputOptions &Opts) {
     77   if (Opts.Targets.empty()) {
     78     PP.getDiagnostics().Report(diag::err_fe_dependency_file_requires_MT);
     79     return;
     80   }
     81 
     82   // Disable the "file not found" diagnostic if the -MG option was given.
     83   if (Opts.AddMissingHeaderDeps)
     84     PP.SetSuppressIncludeNotFoundError(true);
     85 
     86   PP.addPPCallbacks(new DependencyFileCallback(&PP, Opts));
     87 }
     88 
     89 /// FileMatchesDepCriteria - Determine whether the given Filename should be
     90 /// considered as a dependency.
     91 bool DependencyFileCallback::FileMatchesDepCriteria(const char *Filename,
     92                                           SrcMgr::CharacteristicKind FileType) {
     93   if (strcmp("<built-in>", Filename) == 0)
     94     return false;
     95 
     96   if (IncludeSystemHeaders)
     97     return true;
     98 
     99   return FileType == SrcMgr::C_User;
    100 }
    101 
    102 void DependencyFileCallback::FileChanged(SourceLocation Loc,
    103                                          FileChangeReason Reason,
    104                                          SrcMgr::CharacteristicKind FileType,
    105                                          FileID PrevFID) {
    106   if (Reason != PPCallbacks::EnterFile)
    107     return;
    108 
    109   // Dependency generation really does want to go all the way to the
    110   // file entry for a source location to find out what is depended on.
    111   // We do not want #line markers to affect dependency generation!
    112   SourceManager &SM = PP->getSourceManager();
    113 
    114   const FileEntry *FE =
    115     SM.getFileEntryForID(SM.getFileID(SM.getExpansionLoc(Loc)));
    116   if (FE == 0) return;
    117 
    118   StringRef Filename = FE->getName();
    119   if (!FileMatchesDepCriteria(Filename.data(), FileType))
    120     return;
    121 
    122   // Remove leading "./" (or ".//" or "././" etc.)
    123   while (Filename.size() > 2 && Filename[0] == '.' &&
    124          llvm::sys::path::is_separator(Filename[1])) {
    125     Filename = Filename.substr(1);
    126     while (llvm::sys::path::is_separator(Filename[0]))
    127       Filename = Filename.substr(1);
    128   }
    129 
    130   AddFilename(Filename);
    131 }
    132 
    133 void DependencyFileCallback::InclusionDirective(SourceLocation HashLoc,
    134                                                 const Token &IncludeTok,
    135                                                 StringRef FileName,
    136                                                 bool IsAngled,
    137                                                 CharSourceRange FilenameRange,
    138                                                 const FileEntry *File,
    139                                                 StringRef SearchPath,
    140                                                 StringRef RelativePath,
    141                                                 const Module *Imported) {
    142   if (!File) {
    143     if (AddMissingHeaderDeps)
    144       AddFilename(FileName);
    145     else
    146       SeenMissingHeader = true;
    147   }
    148 }
    149 
    150 void DependencyFileCallback::AddFilename(StringRef Filename) {
    151   if (FilesSet.insert(Filename))
    152     Files.push_back(Filename);
    153 }
    154 
    155 /// PrintFilename - GCC escapes spaces, # and $, but apparently not ' or " or
    156 /// other scary characters.
    157 static void PrintFilename(raw_ostream &OS, StringRef Filename) {
    158   for (unsigned i = 0, e = Filename.size(); i != e; ++i) {
    159     if (Filename[i] == ' ' || Filename[i] == '#')
    160       OS << '\\';
    161     else if (Filename[i] == '$') // $ is escaped by $$.
    162       OS << '$';
    163     OS << Filename[i];
    164   }
    165 }
    166 
    167 void DependencyFileCallback::OutputDependencyFile() {
    168   if (SeenMissingHeader) {
    169     bool existed;
    170     llvm::sys::fs::remove(OutputFile, existed);
    171     return;
    172   }
    173 
    174   std::string Err;
    175   llvm::raw_fd_ostream OS(OutputFile.c_str(), Err);
    176   if (!Err.empty()) {
    177     PP->getDiagnostics().Report(diag::err_fe_error_opening)
    178       << OutputFile << Err;
    179     return;
    180   }
    181 
    182   // Write out the dependency targets, trying to avoid overly long
    183   // lines when possible. We try our best to emit exactly the same
    184   // dependency file as GCC (4.2), assuming the included files are the
    185   // same.
    186   const unsigned MaxColumns = 75;
    187   unsigned Columns = 0;
    188 
    189   for (std::vector<std::string>::iterator
    190          I = Targets.begin(), E = Targets.end(); I != E; ++I) {
    191     unsigned N = I->length();
    192     if (Columns == 0) {
    193       Columns += N;
    194     } else if (Columns + N + 2 > MaxColumns) {
    195       Columns = N + 2;
    196       OS << " \\\n  ";
    197     } else {
    198       Columns += N + 1;
    199       OS << ' ';
    200     }
    201     // Targets already quoted as needed.
    202     OS << *I;
    203   }
    204 
    205   OS << ':';
    206   Columns += 1;
    207 
    208   // Now add each dependency in the order it was seen, but avoiding
    209   // duplicates.
    210   for (std::vector<std::string>::iterator I = Files.begin(),
    211          E = Files.end(); I != E; ++I) {
    212     // Start a new line if this would exceed the column limit. Make
    213     // sure to leave space for a trailing " \" in case we need to
    214     // break the line on the next iteration.
    215     unsigned N = I->length();
    216     if (Columns + (N + 1) + 2 > MaxColumns) {
    217       OS << " \\\n ";
    218       Columns = 2;
    219     }
    220     OS << ' ';
    221     PrintFilename(OS, *I);
    222     Columns += N + 1;
    223   }
    224   OS << '\n';
    225 
    226   // Create phony targets if requested.
    227   if (PhonyTarget && !Files.empty()) {
    228     // Skip the first entry, this is always the input file itself.
    229     for (std::vector<std::string>::iterator I = Files.begin() + 1,
    230            E = Files.end(); I != E; ++I) {
    231       OS << '\n';
    232       PrintFilename(OS, *I);
    233       OS << ":\n";
    234     }
    235   }
    236 }
    237 
    238