[PATCH] D76725: [clangd] Build ASTs only with fresh preambles or after building a new preamble

[Kadir Cetinkaya via Phabricator via cfe-commits]

kadircet created this revision.
kadircet added a reviewer: sammccall.
Herald added subscribers: cfe-commits, usaxena95, arphaman, jkorous, MaskRay, javed.absar, ilya-biryukov.
Herald added a project: clang.
kadircet added a parent revision: D76304: [clangd] Update TUStatus api to accommodate preamble thread.

This is another step for out-of-order preamble builds. To keep the
diagnostic behavior same, we only build ASTs either with "reusable" preambles,
the ones that are fully applicable to a given ParseInput, or after building a
new preamble. Which is the same behaviour as what we do today.

ASTs built through preamble callbacks are not cached as they are built on a
different thread and ASTWorker heavily relies on being the only thread updating
cached ASTs. This results in possibly building some ASTs twice (when there's an
immediate read after a preamble built without any write in between).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76725

Files:
  clang-tools-extra/clangd/Preamble.cpp
  clang-tools-extra/clangd/Preamble.h
  clang-tools-extra/clangd/TUScheduler.cpp
  clang-tools-extra/clangd/unittests/FileIndexTests.cpp
  clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp
  clang-tools-extra/clangd/unittests/TestTU.cpp

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