Make DIASession work if msdia*.dll isn't registered.

[thakis]

Summary

This fixes various symbolization test failures for me when I build with a hermetic VS2015 without having run the 2015 installer.

[rnk]

lib/DebugInfo/PDB/DIA/DIASession.cpp

27

LLVM prefers 'static' functions to anonymous namespaces:
http://llvm.org/docs/CodingStandards.html#anonymous-namespaces
*shrug*

[thakis]

lib/DebugInfo/PDB/DIA/DIASession.cpp

27

Yes, but there was already an empty unnamed namespace _right here_! It seemed like fate wanted this to be in an unnamed namespace :-)

(will change before landing)

[thakis]

Zach: Background is that this helps with https://bugs.chromium.org/p/chromium/issues/detail?id=596201 The NoRegCoCreate() technique is from similar code in breakpad.

[zturner]

lib/DebugInfo/PDB/DIA/DIASession.cpp

37–47

Why don't we just check _MSC_VER? That looks equivalent to this whole guid comparison logic.

#if ((_MSC_VER/100) == 19)
    msdia_dll = L"msdia140.dll";
#elif ((_MSC_VER/100) == 18)
    msdia_dll = L"msdia120.dll";

[thakis]

address comments

lib/DebugInfo/PDB/DIA/DIASession.cpp

37–47

Sure, I can do that. The current approach works with compilers that don't set _MSC_VER as long as they understand _uuidof, but that's probably not a very important use case.

Done.

[thakis]

r265193, thanks!

lib/DebugInfo/PDB/DIA/DIASession.cpp

 #include "llvm/DebugInfo/PDB/DIA/DIAEnumSourceFiles.h"
 #include "llvm/DebugInfo/PDB/DIA/DIARawSymbol.h"
 #include "llvm/DebugInfo/PDB/DIA/DIASession.h"
 #include "llvm/DebugInfo/PDB/DIA/DIASourceFile.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolCompiland.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolExe.h"
 #include "llvm/Support/ConvertUTF.h"
 
+#include <diacreate.h>
+
 using namespace llvm;
 
-namespace {}
+namespace {
+
+bool LoadDIA(CComPtr<IDiaDataSource>& DiaDataSource) {
+  if (SUCCEEDED(CoCreateInstance(CLSID_DiaSource, nullptr, CLSCTX_INPROC_SERVER,
+                                 IID_IDiaDataSource,
+                                 reinterpret_cast<LPVOID *>(&DiaDataSource))))
+    return true;
+
+  // If the CoCreateInstance call above failed, msdia*.dll is not registered.
+  // We can try loading the DLL corresponding to the #included DIA SDK, but
+  // the DIA headers don't provide a version. Lets try to figure out which DIA
+  // version we're compiling against by comparing CLSIDs.
+  class DECLSPEC_UUID("3BFCEA48-620F-4B6B-81F7-B9AF75454C7D") DiaSource120;
+  class DECLSPEC_UUID("E6756135-1E65-4D17-8576-610761398C3C") DiaSource140;
+  const wchar_t *msdia_dll = nullptr;
+  if (CLSID_DiaSource == _uuidof(DiaSource120)) // VS2013
+    msdia_dll = L"msdia120.dll";
+  else if (CLSID_DiaSource == _uuidof(DiaSource140)) // VS2015
+    msdia_dll = L"msdia140.dll";
+
+  return msdia_dll &&
+         SUCCEEDED(NoRegCoCreate(msdia_dll, CLSID_DiaSource, IID_IDiaDataSource,
+                                 reinterpret_cast<LPVOID *>(&DiaDataSource)));
+}
+
+}
 
 DIASession::DIASession(CComPtr<IDiaSession> DiaSession) : Session(DiaSession) {}
 
 PDB_ErrorCode DIASession::createFromPdb(StringRef Path,
                                         std::unique_ptr<IPDBSession> &Session) {
   CComPtr<IDiaDataSource> DiaDataSource;
   CComPtr<IDiaSession> DiaSession;
 
   // We assume that CoInitializeEx has already been called by the executable.
-  HRESULT Result = ::CoCreateInstance(
-      CLSID_DiaSource, nullptr, CLSCTX_INPROC_SERVER, IID_IDiaDataSource,
-      reinterpret_cast<LPVOID *>(&DiaDataSource));
-  if (FAILED(Result))
+  if (!LoadDIA(DiaDataSource))
     return PDB_ErrorCode::NoPdbImpl;
 
   llvm::SmallVector<UTF16, 128> Path16;
   if (!llvm::convertUTF8ToUTF16String(Path, Path16))
     return PDB_ErrorCode::InvalidPath;
 
   const wchar_t *Path16Str = reinterpret_cast<const wchar_t*>(Path16.data());
+  HRESULT Result;
   if (FAILED(Result = DiaDataSource->loadDataFromPdb(Path16Str))) {
     if (Result == E_PDB_NOT_FOUND)
       return PDB_ErrorCode::InvalidPath;
     else if (Result == E_PDB_FORMAT)
       return PDB_ErrorCode::InvalidFileFormat;
     else if (Result == E_INVALIDARG)
       return PDB_ErrorCode::InvalidParameter;
     else if (Result == E_UNEXPECTED)

 }
 
 PDB_ErrorCode DIASession::createFromExe(StringRef Path,
                                         std::unique_ptr<IPDBSession> &Session) {
   CComPtr<IDiaDataSource> DiaDataSource;
   CComPtr<IDiaSession> DiaSession;
 
   // We assume that CoInitializeEx has already been called by the executable.
-  HRESULT Result = ::CoCreateInstance(
-      CLSID_DiaSource, nullptr, CLSCTX_INPROC_SERVER, IID_IDiaDataSource,
-      reinterpret_cast<LPVOID *>(&DiaDataSource));
-  if (FAILED(Result))
+  if (!LoadDIA(DiaDataSource))
     return PDB_ErrorCode::NoPdbImpl;
 
   llvm::SmallVector<UTF16, 128> Path16;
   if (!llvm::convertUTF8ToUTF16String(Path, Path16))
     return PDB_ErrorCode::InvalidPath;
 
   const wchar_t *Path16Str = reinterpret_cast<const wchar_t *>(Path16.data());
+  HRESULT Result;
   if (FAILED(Result =
                  DiaDataSource->loadDataForExe(Path16Str, nullptr, nullptr))) {
     if (Result == E_PDB_NOT_FOUND)
       return PDB_ErrorCode::InvalidPath;
     else if (Result == E_PDB_FORMAT)
       return PDB_ErrorCode::InvalidFileFormat;
     else if (Result == E_PDB_INVALID_SIG || Result == E_PDB_INVALID_AGE)
       return PDB_ErrorCode::DebugInfoMismatch;