[llvm-branch-commits] [clang] [serialization] No transitive type change (PR #92511)

[Ilya Biryukov via llvm-branch-commits]

https://github.com/ilya-biryukov commented:

Thanks for the change! I have done a round of review and left a few suggestion and also have a bunch of questions. I am sorry if some of them may look too obvious, I did try to dig into the code where I could, but Clang's serialization is complicated and some things are easier researched through a conversation than through looking at code.  Please bear with me, I promise to get better in the upcoming reviews.

Here are a few extra question that came to mind too.

Question 1: Do we have estimates on how much bigger the PCMs become? Did you observer any negative performance impact?

I would expect `TypeID`s to be much more common than decls, and the corresponding size increases to be more significant. We've already lost ~6% from DeclID change, I am slightly worried the types are going to be a bigger hit.

Question 2: could you explain why we the PCM in your example was changing before? Was there some base offset inherited from the PCM files we depended on?

https://github.com/llvm/llvm-project/pull/92511