RFR: 8365053: Refresh hotspot precompiled.hpp with headers based on current frequency [v14]

[Francesco Andreuzzi]

On Mon, 25 Aug 2025 15:27:54 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> The new PCH file is surprisingly short. But we should trust the performance measurements, and this seems to be much better than the existing file. It might be an indication that gcc/clang have improved in performance for non-PCH headers. If you are up to it, it would be interesting to have a comparison run on your test platforms for running without PCH. You don't have to retest everything you ran, but just some representative selection perhaps? It's not relevant to this PR, but more to the general discussion of how relevant it is to keep PCH at all.

@magicus it seems that PCH still makes quite a difference, I re-ran `server` builds:

| Branch  | Compiler | Build flavor   | Avg     | Stddev |
|---------|----------|-------|---------|--------|
| master  | gcc      | server no-pch| 3375.60 | 2.04   |
| master  | clang    | server  no-pch| 2554.08 | 6.25   |
| master   | gcc    | server   | 2962.90  | 3.04    |
| master   | clang  | server   | 2247.31  | 4.27    |
| 892ecb5a | gcc    | server   | 2570.87  | 0.96    |
| 892ecb5a | clang  | server   | 1824.21  | 2.31    |

The platform is the first in my [comment](https://github.com/openjdk/jdk/pull/26681#issuecomment-3219345092) above.

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PR Comment: https://git.openjdk.org/jdk/pull/26681#issuecomment-3220911147