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Re: [RFC] How to add vector math functions to Glibc
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>
- Cc: Andrew Senkevich <andrew dot n dot senkevich at gmail dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>, libc-alpha <libc-alpha at sourceware dot org>
- Date: Thu, 25 Sep 2014 12:37:46 -0700
- Subject: Re: [RFC] How to add vector math functions to Glibc
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On Thu, Sep 25, 2014 at 12:27 PM, Carlos O'Donell <carlos@redhat.com> wrote:
> On 09/25/2014 11:40 AM, H.J. Lu wrote:
>> On Thu, Sep 25, 2014 at 8:17 AM, Andrew Senkevich
>> <andrew.n.senkevich@gmail.com> wrote:
>>>> If consensus ends up being to have such a library (libmvec or libmvect?),
>>>> then the installation rules for libm.so as a linker script should go in
>>>> math/Makefile, not the toplevel Makerules. (I don't know what if any
>>>> changes might be needed to allow subdirectories to provide libraries as
>>>> linker scripts.)
>>>
>>> There were three options about the place where to add vectorized math functions:
>>>
>>> 1. GLIBC (libm)
>>> 2. GLIBC (additional library)
>>> 3. GCC
>>>
>>> In GLIBC cases build of vectorized functions can be conditional, no
>>> additional -lmvec required because of libm.so installed as linked
>>> script in case of vectorized functions available, so it seems not very
>>> important whether functions located in additional library or in libm.
>>>
>>
>> I don't think they should be in libm since most of applications
>> won't use those vector functions, which increase libm size
>> unnecessarily. A separate library is better.
>
> I agree. A distinct libmvec.so is best.
>
> I see the consensus that #2 is the way forward.
Since this vector library targets GCC, there are
pros to put it in GCC.
--
H.J.