RFR: 8319197: Exclude hb-subset and hb-style from compilation

[Phil Race]

On Tue, 31 Oct 2023 21:32:26 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

> hb-subset and hb-style APIs are not used and not exported by libfontmanger. We can cut the compilation time by not compiling the unused files.
> 
> The added exclusions reduce the build time by ~1 minute (~8%) on my machine. This is with harfbuzz 8, with harfbuzz 7 the improvement was ~30 seconds.
> 
> Client libs tests continue to pass.

So if I have this right,
(1) excluding several unused files from the build saves 60 seconds.
(2) Using the two specific #defines instead saves about 34 seconds.
(3) The two specific #defines on top of the excludes from (1) made no difference
(4) HB_LEAN had no impact either .. I presume you mean  when used on top of (1) as well, which suggests that most of what's in there is cheap to compile.

The build exclusion does however include another couple of files, at least one of which is unrelated, not sure if you ever said
how much that saved, but that presumably accounts for some part of 60 sec vs 34 secs

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PR Comment: https://git.openjdk.org/jdk/pull/16440#issuecomment-1796430552