r177194 - <rdar://problem/13426257> Introduce SDKSettings.plist as an input file dependency for PCH/modules.

[Jean-Daniel Dupas]

Out of curiosity, what happen while compiling on Darwin without specifying an sdkroot as in such case, it uses headers from /System directly and will not be able to locate a SDKSettings.plist file.



Le 15 mars 2013 à 23:15, Douglas Gregor <dgregor at apple.com> a écrit :

> Author: dgregor
> Date: Fri Mar 15 17:15:07 2013
> New Revision: 177194
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=177194&view=rev
> Log:
> <rdar://problem/13426257> Introduce SDKSettings.plist as an input file dependency for PCH/modules.
> 
> When we're building a precompiled header or module against an SDK on
> Darwin, there will be a file SDKSettings.plist in the sysroot. Since
> stat()'ing every system header on which a module or PCH file depends
> is performance suicide, we instead stat() just SDKSettings.plist. This
> hack works well on Darwin; it's unclear how we want to handle this on
> other platforms. If there is a canonical file, we should use it; if
> not, we either have to take the performance hit of stat()'ing system
> headers repeatedly or roll the dice by not checking anything.
> 
> Modified:
>    cfe/trunk/include/clang/Serialization/ASTWriter.h
>    cfe/trunk/lib/Serialization/ASTWriter.cpp
> 
> Modified: cfe/trunk/include/clang/Serialization/ASTWriter.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Serialization/ASTWriter.h?rev=177194&r1=177193&r2=177194&view=diff
> ==============================================================================
> --- cfe/trunk/include/clang/Serialization/ASTWriter.h (original)
> +++ cfe/trunk/include/clang/Serialization/ASTWriter.h Fri Mar 15 17:15:07 2013
> @@ -48,6 +48,7 @@ class CXXCtorInitializer;
> class FileEntry;
> class FPOptions;
> class HeaderSearch;
> +class HeaderSearchOptions;
> class IdentifierResolver;
> class MacroDefinition;
> class OpaqueValueExpr;
> @@ -416,7 +417,9 @@ private:
>   void WriteBlockInfoBlock();
>   void WriteControlBlock(Preprocessor &PP, ASTContext &Context,
>                          StringRef isysroot, const std::string &OutputFile);
> -  void WriteInputFiles(SourceManager &SourceMgr, StringRef isysroot);
> +  void WriteInputFiles(SourceManager &SourceMgr,
> +                       HeaderSearchOptions &HSOpts,
> +                       StringRef isysroot);
>   void WriteSourceManagerBlock(SourceManager &SourceMgr,
>                                const Preprocessor &PP,
>                                StringRef isysroot);
> 
> Modified: cfe/trunk/lib/Serialization/ASTWriter.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTWriter.cpp?rev=177194&r1=177193&r2=177194&view=diff
> ==============================================================================
> --- cfe/trunk/lib/Serialization/ASTWriter.cpp (original)
> +++ cfe/trunk/lib/Serialization/ASTWriter.cpp Fri Mar 15 17:15:07 2013
> @@ -1213,11 +1213,24 @@ void ASTWriter::WriteControlBlock(Prepro
>     Stream.EmitRecordWithBlob(AbbrevCode, Record, origDir);
>   }
> 
> -  WriteInputFiles(Context.SourceMgr, isysroot);
> +  WriteInputFiles(Context.SourceMgr,
> +                  PP.getHeaderSearchInfo().getHeaderSearchOpts(),
> +                  isysroot);
>   Stream.ExitBlock();
> }
> 
> -void ASTWriter::WriteInputFiles(SourceManager &SourceMgr, StringRef isysroot) {
> +namespace  {
> +  /// \brief An input file.
> +  struct InputFileEntry {
> +    const FileEntry *File;
> +    bool IsSystemFile;
> +    bool BufferOverridden;
> +  };
> +}
> +
> +void ASTWriter::WriteInputFiles(SourceManager &SourceMgr,
> +                                HeaderSearchOptions &HSOpts,
> +                                StringRef isysroot) {
>   using namespace llvm;
>   Stream.EnterSubblock(INPUT_FILES_BLOCK_ID, 4);
>   RecordData Record;
> @@ -1234,7 +1247,7 @@ void ASTWriter::WriteInputFiles(SourceMa
> 
>   // Get all ContentCache objects for files, sorted by whether the file is a
>   // system one or not. System files go at the back, users files at the front.
> -  std::deque<const SrcMgr::ContentCache *> SortedFiles;
> +  std::deque<InputFileEntry> SortedFiles;
>   for (unsigned I = 1, N = SourceMgr.local_sloc_entry_size(); I != N; ++I) {
>     // Get this source location entry.
>     const SrcMgr::SLocEntry *SLoc = &SourceMgr.getLocalSLocEntry(I);
> @@ -1247,20 +1260,38 @@ void ASTWriter::WriteInputFiles(SourceMa
>     if (!Cache->OrigEntry)
>       continue;
> 
> +    InputFileEntry Entry;
> +    Entry.File = Cache->OrigEntry;
> +    Entry.IsSystemFile = Cache->IsSystemFile;
> +    Entry.BufferOverridden = Cache->BufferOverridden;
>     if (Cache->IsSystemFile)
> -      SortedFiles.push_back(Cache);
> +      SortedFiles.push_back(Entry);
>     else
> -      SortedFiles.push_front(Cache);
> +      SortedFiles.push_front(Entry);
> +  }
> +
> +  // If we have an isysroot for a Darwin SDK, include its SDKSettings.plist in
> +  // the set of (non-system) input files. This is simple heuristic for
> +  // detecting whether the system headers may have changed, because it is too
> +  // expensive to stat() all of the system headers.
> +  FileManager &FileMgr = SourceMgr.getFileManager();
> +  if (!HSOpts.Sysroot.empty()) {
> +    llvm::SmallString<128> SDKSettingsFileName(HSOpts.Sysroot);
> +    llvm::sys::path::append(SDKSettingsFileName, "SDKSettings.plist");
> +    if (const FileEntry *SDKSettingsFile = FileMgr.getFile(SDKSettingsFileName)) {
> +      InputFileEntry Entry = { SDKSettingsFile, false, false };
> +      SortedFiles.push_front(Entry);
> +    }
>   }
> 
>   unsigned UserFilesNum = 0;
>   // Write out all of the input files.
>   std::vector<uint32_t> InputFileOffsets;
> -  for (std::deque<const SrcMgr::ContentCache *>::iterator
> +  for (std::deque<InputFileEntry>::iterator
>          I = SortedFiles.begin(), E = SortedFiles.end(); I != E; ++I) {
> -    const SrcMgr::ContentCache *Cache = *I;
> +    const InputFileEntry &Entry = *I;
> 
> -    uint32_t &InputFileID = InputFileIDs[Cache->OrigEntry];
> +    uint32_t &InputFileID = InputFileIDs[Entry.File];
>     if (InputFileID != 0)
>       continue; // already recorded this file.
> 
> @@ -1269,7 +1300,7 @@ void ASTWriter::WriteInputFiles(SourceMa
> 
>     InputFileID = InputFileOffsets.size();
> 
> -    if (!Cache->IsSystemFile)
> +    if (!Entry.IsSystemFile)
>       ++UserFilesNum;
> 
>     Record.clear();
> @@ -1277,19 +1308,19 @@ void ASTWriter::WriteInputFiles(SourceMa
>     Record.push_back(InputFileOffsets.size());
> 
>     // Emit size/modification time for this file.
> -    Record.push_back(Cache->OrigEntry->getSize());
> -    Record.push_back(Cache->OrigEntry->getModificationTime());
> +    Record.push_back(Entry.File->getSize());
> +    Record.push_back(Entry.File->getModificationTime());
> 
>     // Whether this file was overridden.
> -    Record.push_back(Cache->BufferOverridden);
> +    Record.push_back(Entry.BufferOverridden);
> 
>     // Turn the file name into an absolute path, if it isn't already.
> -    const char *Filename = Cache->OrigEntry->getName();
> +    const char *Filename = Entry.File->getName();
>     SmallString<128> FilePath(Filename);
> 
>     // Ask the file manager to fixup the relative path for us. This will 
>     // honor the working directory.
> -    SourceMgr.getFileManager().FixupRelativePath(FilePath);
> +    FileMgr.FixupRelativePath(FilePath);
> 
>     // FIXME: This call to make_absolute shouldn't be necessary, the
>     // call to FixupRelativePath should always return an absolute path.
> @@ -1300,7 +1331,7 @@ void ASTWriter::WriteInputFiles(SourceMa
> 
>     Stream.EmitRecordWithBlob(IFAbbrevCode, Record, Filename);
>   }  
> -  
> +
>   Stream.ExitBlock();
> 
>   // Create input file offsets abbreviation.
> 
> 
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-- Jean-Daniel