"Zack Weinberg" <zack@owlfolio.org> writes:

> To figure out if this is a workable idea, questions for you all:
> (1) Are there other use cases for ifuncs that I don't know about?
> (2) Are there existing ifuncs that perform CPU-capability-based
> function selection that *could not* be replaced with an array of bit
> vectors like what I sketched in the previous paragraph?

Interesting take.  I have recently looked at lib25519 and libmceliece
which uses ifuncs to select crypto primitives.  While I think it may be
possible to rewrite it for something you suggest, I think libraries like
this suggests that some developer find the ifunc interface useful and
that rewriting things will require some discussion.  Take this as a +0.9.

https://salsa.debian.org/debian/lib25519
https://salsa.debian.org/debian/libmceliece

Some relevant selector logic code:
https://salsa.debian.org/debian/libmceliece/-/blob/main/scripts-build/dispatch
https://salsa.debian.org/debian/libmceliece/-/blob/main/cpuid/amd64.c

/Simon