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Re: [PATCH] S390: Refactor ifunc handling


On Thu, 6 Dec 2018, Adhemerval Zanella wrote:

> builds with loader selecting the path depending of the hwcap value). I really
> would like we we move to deprecate and remove the --with-cpu option, so we 
> have basically just two variants (enable and disable multiarch).

I'd like to deprecate and remove --with-cpu - but replace it with the 
default CPU being automatically determined by how the compiler behaves 
(see <https://sourceware.org/ml/libc-alpha/2017-02/msg00154.html>).

Avoiding building in lots of function variants for CPUs older than the 
minimum supported still seems appropriate to me.  What I don't know is if 
there is a good way to design things with the following properties:

* IFUNC function variants are handled the same way for all architectures.

* A function is automatically not an IFUNC if the minimum supported CPU 
implies one particular version would always be used.

* If more than one function might be used based on the minimum supported 
CPU, all those that wouldn't ever be used automatically get compiled out.

* A single optimal version (choice based on the compiler's code 
generation) is automatically selected in the non-multiarch case.

-- 
Joseph S. Myers
joseph@codesourcery.com


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