Introduce the notion of "Relocatable" precompiled headers, which are built

with a particular system root directory and can be used with a different
system root directory when the headers it depends on have been installed.
Relocatable precompiled headers rewrite the file names of the headers used
when generating the PCH file into the corresponding file names of the 
headers available when using the PCH file.

Addresses <rdar://problem/7001604>.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74885 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 53 insertions, 8 deletions

diff --git a/include/clang/Frontend/ASTConsumers.h b/include/clang/Frontend/ASTConsumers.h
index be45202625..fe5a198880 100644
--- a/include/clang/Frontend/ASTConsumers.h
+++ b/include/clang/Frontend/ASTConsumers.h
@@ -92,7 +92,8 @@ ASTConsumer* CreateHTMLPrinter(llvm::raw_ostream *OS, Diagnostic &D,
 // used later with the PCHReader (clang-cc option -include-pch)
 // to speed up compile times.
 ASTConsumer *CreatePCHGenerator(const Preprocessor &PP,
-                                llvm::raw_ostream *OS);
+                                llvm::raw_ostream *OS,
+                                const char *isysroot = 0);
 
 // Block rewriter: rewrites code using the Apple blocks extension to pure
 // C code.  Output is always sent to stdout.
diff --git a/include/clang/Frontend/PCHReader.h b/include/clang/Frontend/PCHReader.h
index d2849fe7c9..aa984175e0 100644
--- a/include/clang/Frontend/PCHReader.h
+++ b/include/clang/Frontend/PCHReader.h
@@ -310,6 +310,13 @@ private:
   /// file.
   std::string OriginalFileName;
 
+  /// \brief Whether this precompiled header is a relocatable PCH file.
+  bool RelocatablePCH;
+  
+  /// \brief The system include root to be used when loading the 
+  /// precompiled header.
+  const char *isysroot;
+      
   /// \brief Mapping from switch-case IDs in the PCH file to
   /// switch-case statements.
   std::map<unsigned, SwitchCase *> SwitchCaseStmts;
@@ -428,10 +435,13 @@ private:
   /// predefines buffer may contain additional definitions.
   std::string SuggestedPredefines;
   
+  void MaybeAddSystemRootToFilename(std::string &Filename);
+      
   PCHReadResult ReadPCHBlock();
   bool CheckPredefinesBuffer(const char *PCHPredef, 
                              unsigned PCHPredefLen,
                              FileID PCHBufferID);
+  bool ParseLineTable(llvm::SmallVectorImpl<uint64_t> &Record);
   PCHReadResult ReadSourceManagerBlock();
   PCHReadResult ReadSLocEntryRecord(unsigned ID);
   
@@ -448,19 +458,42 @@ private:
 
   PCHReader(const PCHReader&); // do not implement
   PCHReader &operator=(const PCHReader &); // do not implement
-
 public:
   typedef llvm::SmallVector<uint64_t, 64> RecordData;
 
   /// \brief Load the PCH file and validate its contents against the given
   /// Preprocessor.
-  PCHReader(Preprocessor &PP, ASTContext *Context);
+  ///
+  /// \param PP the preprocessor associated with the context in which this
+  /// precompiled header will be loaded.
+  ///
+  /// \param Context the AST context that this precompiled header will be
+  /// loaded into.
+  ///
+  /// \param isysroot If non-NULL, the system include path specified by the
+  /// user. This is only used with relocatable PCH files. If non-NULL,
+  /// a relocatable PCH file will use the default path "/".
+  PCHReader(Preprocessor &PP, ASTContext *Context, const char *isysroot = 0);
   
   /// \brief Load the PCH file without using any pre-initialized Preprocessor.
   ///
   /// The necessary information to initialize a Preprocessor later can be
   /// obtained by setting a PCHReaderListener.
-  PCHReader(SourceManager &SourceMgr, FileManager &FileMgr, Diagnostic &Diags);
+  ///
+  /// \param SourceMgr the source manager into which the precompiled header
+  /// will be loaded.
+  ///
+  /// \param FileMgr the file manager into which the precompiled header will
+  /// be loaded.
+  ///
+  /// \param Diags the diagnostics system to use for reporting errors and
+  /// warnings relevant to loading the precompiled header.
+  ///
+  /// \param isysroot If non-NULL, the system include path specified by the
+  /// user. This is only used with relocatable PCH files. If non-NULL,
+  /// a relocatable PCH file will use the default path "/".
+      PCHReader(SourceManager &SourceMgr, FileManager &FileMgr, 
+                Diagnostic &Diags, const char *isysroot = 0);
   ~PCHReader();
 
   /// \brief Load the precompiled header designated by the given file
diff --git a/include/clang/Frontend/PCHWriter.h b/include/clang/Frontend/PCHWriter.h
index c663442e64..3bab9b998b 100644
--- a/include/clang/Frontend/PCHWriter.h
+++ b/include/clang/Frontend/PCHWriter.h
@@ -160,11 +160,12 @@ private:
   unsigned NumVisibleDeclContexts;
 
   void WriteBlockInfoBlock();
-  void WriteMetadata(ASTContext &Context);
+  void WriteMetadata(ASTContext &Context, const char *isysroot);
   void WriteLanguageOptions(const LangOptions &LangOpts);
-  void WriteStatCache(MemorizeStatCalls &StatCalls);
+  void WriteStatCache(MemorizeStatCalls &StatCalls, const char* isysroot);
   void WriteSourceManagerBlock(SourceManager &SourceMgr, 
-                               const Preprocessor &PP);
+                               const Preprocessor &PP,
+                               const char* isysroot);
   void WritePreprocessor(const Preprocessor &PP);
   void WriteComments(ASTContext &Context);
   void WriteType(const Type *T);
@@ -186,7 +187,17 @@ public:
   PCHWriter(llvm::BitstreamWriter &Stream);
   
   /// \brief Write a precompiled header for the given semantic analysis.
-  void WritePCH(Sema &SemaRef, MemorizeStatCalls *StatCalls);
+  ///
+  /// \param SemaRef a reference to the semantic analysis object that processed
+  /// the AST to be written into the precompiled header.
+  ///
+  /// \param StatCalls the object that cached all of the stat() calls made while
+  /// searching for source files and headers.
+  ///
+  /// \param isysroot if non-NULL, write a relocatable PCH file whose headers 
+  /// are relative to the given system root.
+  void WritePCH(Sema &SemaRef, MemorizeStatCalls *StatCalls, 
+                const char* isysroot);
 
   /// \brief Emit a source location.
   void AddSourceLocation(SourceLocation Loc, RecordData &Record);