Introduce a PCHContainerOperations interface (NFC).

A PCHContainerOperations abstract interface provides operations for
creating and unwrapping containers for serialized ASTs (precompiled
headers and clang modules). The default implementation is
RawPCHContainerOperations, which uses a flat file for the output.

The main application for this interface will be an
ObjectFilePCHContainerOperations implementation that uses LLVM to
wrap the module in an ELF/Mach-O/COFF container to store debug info
alongside the AST.

rdar://problem/20091852

llvm-svn: 240225

clang/lib/Serialization/ModuleManager.cpp

@@ -11,6 +11,7 @@
 //  modules for the ASTReader.
 //
 //===----------------------------------------------------------------------===//
+#include "clang/Frontend/PCHContainerOperations.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/ModuleMap.h"
 #include "clang/Serialization/GlobalModuleIndex.h"
@@ -136,10 +137,9 @@ ModuleManager::addModule(StringRef FileName, ModuleKind Type,
 
       New->Buffer = std::move(*Buf);
     }
-    
-    // Initialize the stream
-    New->StreamFile.init((const unsigned char *)New->Buffer->getBufferStart(),
-                         (const unsigned char *)New->Buffer->getBufferEnd());
+
+    // Initialize the stream.
+    PCHContainerOps.ExtractPCH(New->Buffer->getMemBufferRef(), New->StreamFile);
   }
 
   if (ExpectedSignature) {
@@ -289,8 +289,10 @@ void ModuleManager::moduleFileAccepted(ModuleFile *MF) {
   ModulesInCommonWithGlobalIndex.push_back(MF);
 }
 
-ModuleManager::ModuleManager(FileManager &FileMgr)
-  : FileMgr(FileMgr), GlobalIndex(), FirstVisitState(nullptr) {}
+ModuleManager::ModuleManager(FileManager &FileMgr,
+                             const PCHContainerOperations &PCHContainerOps)
+    : FileMgr(FileMgr), PCHContainerOps(PCHContainerOps), GlobalIndex(),
+      FirstVisitState(nullptr) {}
 
 ModuleManager::~ModuleManager() {
   for (unsigned i = 0, e = Chain.size(); i != e; ++i)