https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125253
--- Comment #7 from Sam James <sjames at gcc dot gnu.org> ---
It's probably not a good first bug if you haven't done it before.
You generally need to:
* bisect by objects (have a good and bad build directory, copy over from
bad->good, reset after each attempt, to bisect the list of objects to find
which one is miscompiled). Just one is bad if no LTO (with some extremely
unlikely exceptions I've never seen).
* bisect by pragmas, i.e. `#pragma GCC push_options`, `#pragma GCC
optimize("O0")`) with code in the middle then `#pragma GCC pop_options`
* hack away at the source file, and/or start copying the miscompiled function
into its own source file s.t. it still has the misbehaviour
* cvise at the end to make it smaller
There's no magic technique and it's time-consuming.
I can do it for Highway but I'd prefer not to: I did it Highway already for
PR121310 which was a dupe of PR111231 (not offended, but it's just that it was
time-consuming and I have a feeling it is the same bug again).
