[clang] Refactor doc comments to Decls attribution

- Create ASTContext::attachCommentsToJustParsedDecls so we don't have to load external comments in Sema when trying to attach existing comments to just parsed Decls.
- Keep comments ordered and cache their decomposed location - faster SourceLoc-based searching.
- Optimize work with redeclarations.
- Keep one comment per redeclaration chain (represented by canonical Decl) instead of comment per redeclaration.
- For redeclaration chains with no comment attached keep just the last declaration in chain that had no comment instead of every comment-less redeclaration.

Differential Revision: https://reviews.llvm.org/D65301

llvm-svn: 368732

1 files changed, 11 insertions, 4 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index dc54025fb44..5d6f17e3f0c 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -9731,10 +9731,17 @@ void ASTReader::ReadComments() {
       }
     }
   NextCursor:
-    // De-serialized SourceLocations get negative FileIDs for other modules,
-    // potentially invalidating the original order. Sort it again.
-    llvm::sort(Comments, BeforeThanCompare<RawComment>(SourceMgr));
-    Context.Comments.addDeserializedComments(Comments);
+    llvm::DenseMap<FileID, std::map<unsigned, RawComment *>>
+        FileToOffsetToComment;
+    for (RawComment *C : Comments) {
+      SourceLocation CommentLoc = C->getBeginLoc();
+      if (CommentLoc.isValid()) {
+        std::pair<FileID, unsigned> Loc =
+            SourceMgr.getDecomposedLoc(CommentLoc);
+        if (Loc.first.isValid())
+          Context.Comments.OrderedComments[Loc.first].emplace(Loc.second, C);
+      }
+    }
   }
 }