Rather than rejecting attempts to run preprocessor-only actions on AST files,

replay the steps taken to create the AST file with the preprocessor-only action
installed to produce preprocessed output.

This can be used to produce the preprocessed text for an existing .pch or .pcm
file.

llvm-svn: 304726

1 files changed, 35 insertions, 0 deletions

diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index c5cff74ac97..c0cd2a8d2a1 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -345,6 +345,41 @@ void SourceManager::clearIDTables() {
   createExpansionLoc(SourceLocation(),SourceLocation(),SourceLocation(), 1);
 }
 
+void SourceManager::initializeForReplay(const SourceManager &Old) {
+  assert(MainFileID.isInvalid() && "expected uninitialized SourceManager");
+
+  auto CloneContentCache = [&](const ContentCache *Cache) -> ContentCache * {
+    auto *Clone = new (ContentCacheAlloc.Allocate<ContentCache>()) ContentCache;
+    Clone->OrigEntry = Cache->OrigEntry;
+    Clone->ContentsEntry = Cache->ContentsEntry;
+    Clone->BufferOverridden = Cache->BufferOverridden;
+    Clone->IsSystemFile = Cache->IsSystemFile;
+    Clone->IsTransient = Cache->IsTransient;
+    Clone->replaceBuffer(Cache->getRawBuffer(), /*DoNotFree*/true);
+    return Clone;
+  };
+
+  // Set up our main file ID as a copy of the old source manager's main file.
+  const SLocEntry &OldMainFile = Old.getSLocEntry(Old.getMainFileID());
+  assert(OldMainFile.isFile() && "main file is macro expansion?");
+  setMainFileID(createFileID(
+      CloneContentCache(OldMainFile.getFile().getContentCache()),
+      SourceLocation(), OldMainFile.getFile().getFileCharacteristic(), 0, 0));
+
+  // Ensure all SLocEntries are loaded from the external source.
+  for (unsigned I = 0, N = Old.LoadedSLocEntryTable.size(); I != N; ++I)
+    if (!Old.SLocEntryLoaded[I])
+      Old.loadSLocEntry(I, nullptr);
+
+  // Inherit any content cache data from the old source manager.
+  for (auto &FileInfo : Old.FileInfos) {
+    SrcMgr::ContentCache *&Slot = FileInfos[FileInfo.first];
+    if (Slot)
+      continue;
+    Slot = CloneContentCache(FileInfo.second);
+  }
+}
+
 /// getOrCreateContentCache - Create or return a cached ContentCache for the
 /// specified file.
 const ContentCache *