[backported/clang-7][Frontend] Honor UserFilesAreVolatile flag getting file buffer in ASTUnit

--------------------------------------------------------------------------
* https://reviews.llvm.org/D47460
--------------------------------------------------------------------------

Do not memory map the main file if the flag UserFilesAreVolatile
is set to true in ASTUnit when calling FileSystem::getBufferForFile.

Task-number: QTCREATORBUG-15449
Change-Id: I283d684f4c1ca38a4689ce09bd594700678679c1
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

2 files changed, 11 insertions, 8 deletions

diff --git a/lib/Basic/FileManager.cpp b/lib/Basic/FileManager.cpp
index a3e226d6cc..c1b9693ee8 100644
--- a/lib/Basic/FileManager.cpp
+++ b/lib/Basic/FileManager.cpp
@@ -450,13 +450,13 @@ FileManager::getBufferForFile(const FileEntry *Entry, bool isVolatile,
 }
 
 llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>>
-FileManager::getBufferForFile(StringRef Filename) {
+FileManager::getBufferForFile(StringRef Filename, bool isVolatile) {
   if (FileSystemOpts.WorkingDir.empty())
-    return FS->getBufferForFile(Filename);
+    return FS->getBufferForFile(Filename, -1, true, isVolatile);
 
   SmallString<128> FilePath(Filename);
   FixupRelativePath(FilePath);
-  return FS->getBufferForFile(FilePath.c_str());
+  return FS->getBufferForFile(FilePath.c_str(), -1, true, isVolatile);
 }
 
 /// getStatValue - Get the 'stat' information for the specified path,
diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index c334e3e6db..1ec4502ba5 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -100,7 +100,8 @@ namespace {
 static std::unique_ptr<llvm::MemoryBuffer>
 getBufferForFileHandlingRemapping(const CompilerInvocation &Invocation,
                                   vfs::FileSystem *VFS,
-                                  StringRef FilePath) {
+                                  StringRef FilePath,
+                                  bool isVolatile) {
   const auto &PreprocessorOpts = Invocation.getPreprocessorOpts();
 
   // Try to determine if the main file has been remapped, either from the
@@ -120,7 +121,8 @@ getBufferForFileHandlingRemapping(const CompilerInvocation &Invocation,
         llvm::sys::fs::UniqueID MID = MPathStatus->getUniqueID();
         if (MainFileID == MID) {
           // We found a remapping. Try to load the resulting, remapped source.
-          BufferOwner = valueOrNull(VFS->getBufferForFile(RF.second));
+          BufferOwner = valueOrNull(
+              VFS->getBufferForFile(RF.second, -1, true, isVolatile));
           if (!BufferOwner)
             return nullptr;
         }
@@ -145,7 +147,8 @@ getBufferForFileHandlingRemapping(const CompilerInvocation &Invocation,
 
   // If the main source file was not remapped, load it now.
   if (!Buffer && !BufferOwner) {
-    BufferOwner = valueOrNull(VFS->getBufferForFile(FilePath));
+    BufferOwner =
+        valueOrNull(VFS->getBufferForFile(FilePath, -1, true, isVolatile));
     if (!BufferOwner)
       return nullptr;
   }
@@ -664,7 +667,7 @@ ASTDeserializationListener *ASTUnit::getDeserializationListener() {
 std::unique_ptr<llvm::MemoryBuffer>
 ASTUnit::getBufferForFile(StringRef Filename, std::string *ErrorStr) {
   assert(FileMgr);
-  auto Buffer = FileMgr->getBufferForFile(Filename);
+  auto Buffer = FileMgr->getBufferForFile(Filename, UserFilesAreVolatile);
   if (Buffer)
     return std::move(*Buffer);
   if (ErrorStr)
@@ -1231,7 +1234,7 @@ ASTUnit::getMainBufferWithPrecompiledPreamble(
       PreambleInvocationIn.getFrontendOpts().Inputs[0].getFile();
   std::unique_ptr<llvm::MemoryBuffer> MainFileBuffer =
       getBufferForFileHandlingRemapping(PreambleInvocationIn, VFS.get(),
-                                        MainFilePath);
+                                        MainFilePath, UserFilesAreVolatile);
   if (!MainFileBuffer)
     return nullptr;