[clang] [clang-tools-extra] [Clang] [NFC] Migrate more AST visitors (PR #160290)

[via cfe-commits]

Sirraide wrote:

> 1- How many instantiations these have
> -Thus: How much space taken, and saved by switch

For the ones outside clang-tools-extra, none are in headers so they just replace one instantiation each.

2- Which are hot-path enough to affect benchmarks, and which are irrelevant

The conclusion we arrived at last time is that the performance is the same, and the regressions are beacuse more vtables means more relocations; last time I tested that by migrating only the unexpanded parameter packs visitor and observed no difference in performance, so I would assume this is a similar situation, but I’ll revert this change for some of the visitors in codegen and see if this changes anything.

https://github.com/llvm/llvm-project/pull/160290