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>.

llvm-svn: 74885

1 files changed, 48 insertions, 11 deletions

diff --git a/clang/lib/Frontend/PCHReader.cpp b/clang/lib/Frontend/PCHReader.cpp
index 067cce9b309..bc0e7208d31 100644
--- a/clang/lib/Frontend/PCHReader.cpp
+++ b/clang/lib/Frontend/PCHReader.cpp
@@ -336,7 +336,8 @@ void PCHValidator::ReadCounter(unsigned Value) {
 // PCH reader implementation
 //===----------------------------------------------------------------------===//
 
-PCHReader::PCHReader(Preprocessor &PP, ASTContext *Context) 
+PCHReader::PCHReader(Preprocessor &PP, ASTContext *Context, 
+                     const char *isysroot) 
   : Listener(new PCHValidator(PP, *this)), SourceMgr(PP.getSourceManager()),
     FileMgr(PP.getFileManager()), Diags(PP.getDiagnostics()),
     SemaObj(0), PP(&PP), Context(Context), Consumer(0),
@@ -344,25 +345,31 @@ PCHReader::PCHReader(Preprocessor &PP, ASTContext *Context)
     IdentifierOffsets(0),
     MethodPoolLookupTable(0), MethodPoolLookupTableData(0),
     TotalSelectorsInMethodPool(0), SelectorOffsets(0),
-    TotalNumSelectors(0), Comments(0), NumComments(0), 
+    TotalNumSelectors(0), Comments(0), NumComments(0), isysroot(isysroot),
     NumStatHits(0), NumStatMisses(0), 
     NumSLocEntriesRead(0), NumStatementsRead(0), 
     NumMacrosRead(0), NumMethodPoolSelectorsRead(0), NumMethodPoolMisses(0),
-    NumLexicalDeclContextsRead(0), NumVisibleDeclContextsRead(0) { }
+    NumLexicalDeclContextsRead(0), NumVisibleDeclContextsRead(0),
+    CurrentlyLoadingTypeOrDecl(0) { 
+  RelocatablePCH = false;
+}
 
 PCHReader::PCHReader(SourceManager &SourceMgr, FileManager &FileMgr,
-                     Diagnostic &Diags) 
+                     Diagnostic &Diags, const char *isysroot) 
   : SourceMgr(SourceMgr), FileMgr(FileMgr), Diags(Diags),
     SemaObj(0), PP(0), Context(0), Consumer(0),
     IdentifierTableData(0), IdentifierLookupTable(0),
     IdentifierOffsets(0),
     MethodPoolLookupTable(0), MethodPoolLookupTableData(0),
     TotalSelectorsInMethodPool(0), SelectorOffsets(0),
-    TotalNumSelectors(0), NumStatHits(0), NumStatMisses(0), 
+    TotalNumSelectors(0), Comments(0), NumComments(0), isysroot(isysroot),
+    NumStatHits(0), NumStatMisses(0), 
     NumSLocEntriesRead(0), NumStatementsRead(0), 
     NumMacrosRead(0), NumMethodPoolSelectorsRead(0), NumMethodPoolMisses(0),
     NumLexicalDeclContextsRead(0), NumVisibleDeclContextsRead(0),
-    CurrentlyLoadingTypeOrDecl(0) { }
+    CurrentlyLoadingTypeOrDecl(0) { 
+  RelocatablePCH = false;
+}
 
 PCHReader::~PCHReader() {}
 
@@ -652,8 +659,7 @@ bool PCHReader::CheckPredefinesBuffer(const char *PCHPredef,
 
 /// \brief Read the line table in the source manager block.
 /// \returns true if ther was an error.
-static bool ParseLineTable(SourceManager &SourceMgr, 
-                           llvm::SmallVectorImpl<uint64_t> &Record) {
+bool PCHReader::ParseLineTable(llvm::SmallVectorImpl<uint64_t> &Record) {
   unsigned Idx = 0;
   LineTableInfo &LineTable = SourceMgr.getLineTable();
 
@@ -664,6 +670,7 @@ static bool ParseLineTable(SourceManager &SourceMgr,
     unsigned FilenameLen = Record[Idx++];
     std::string Filename(&Record[Idx], &Record[Idx] + FilenameLen);
     Idx += FilenameLen;
+    MaybeAddSystemRootToFilename(Filename);
     FileIDs[I] = LineTable.getLineTableFilenameID(Filename.c_str(), 
                                                   Filename.size());
   }
@@ -859,7 +866,7 @@ PCHReader::PCHReadResult PCHReader::ReadSourceManagerBlock() {
       break;
 
     case pch::SM_LINE_TABLE:
-      if (ParseLineTable(SourceMgr, Record))
+      if (ParseLineTable(Record))
         return Failure;
       break;
 
@@ -912,10 +919,12 @@ PCHReader::PCHReadResult PCHReader::ReadSLocEntryRecord(unsigned ID) {
     return Failure;
 
   case pch::SM_SLOC_FILE_ENTRY: {
-    const FileEntry *File = FileMgr.getFile(BlobStart, BlobStart + BlobLen);
+    std::string Filename(BlobStart, BlobStart + BlobLen);
+    MaybeAddSystemRootToFilename(Filename);
+    const FileEntry *File = FileMgr.getFile(Filename);
     if (File == 0) {
       std::string ErrorStr = "could not find file '";
-      ErrorStr.append(BlobStart, BlobLen);
+      ErrorStr += Filename;
       ErrorStr += "' referenced by PCH file";
       Error(ErrorStr.c_str());
       return Failure;
@@ -1096,6 +1105,32 @@ void PCHReader::ReadMacroRecord(uint64_t Offset) {
   }
 }
 
+/// \brief If we are loading a relocatable PCH file, and the filename is
+/// not an absolute path, add the system root to the beginning of the file
+/// name.
+void PCHReader::MaybeAddSystemRootToFilename(std::string &Filename) {
+  // If this is not a relocatable PCH file, there's nothing to do.
+  if (!RelocatablePCH)
+    return;
+  
+  if (Filename.empty() || Filename[0] == '/' || Filename[0] == '<')
+    return;
+
+  std::string FIXME = Filename;
+  
+  if (isysroot == 0) {
+    // If no system root was given, default to '/'
+    Filename.insert(Filename.begin(), '/');
+    return;
+  }
+  
+  unsigned Length = strlen(isysroot);
+  if (isysroot[Length - 1] != '/')
+    Filename.insert(Filename.begin(), '/');
+    
+  Filename.insert(Filename.begin(), isysroot, isysroot + Length);
+}
+
 PCHReader::PCHReadResult 
 PCHReader::ReadPCHBlock() {
   if (Stream.EnterSubBlock(pch::PCH_BLOCK_ID)) {
@@ -1208,6 +1243,7 @@ PCHReader::ReadPCHBlock() {
         return IgnorePCH;
       }
 
+      RelocatablePCH = Record[4];
       if (Listener) {
         std::string TargetTriple(BlobStart, BlobLen);
         if (Listener->ReadTargetTriple(TargetTriple))
@@ -1338,6 +1374,7 @@ PCHReader::ReadPCHBlock() {
 
     case pch::ORIGINAL_FILE_NAME:
       OriginalFileName.assign(BlobStart, BlobLen);
+      MaybeAddSystemRootToFilename(OriginalFileName);
       break;
         
     case pch::COMMENT_RANGES: