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Re: [PATCH 1/N] x86_64 vectorization support: vectorized math functions addition to Glibc
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Andi Kleen <andi at firstfloor dot org>, Rich Felker <dalias at libc dot org>
- Cc: Matthew Fortune <Matthew dot Fortune at imgtec dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>, Andrew Senkevich <andrew dot n dot senkevich at gmail dot com>, libc-alpha <libc-alpha at sourceware dot org>, "igor dot zamyatin at intel dot com" <igor dot zamyatin at intel dot com>, "Melik-Adamyan\, Areg" <areg dot melik-adamyan at intel dot com>, "jakub at redhat dot com" <jakub at redhat dot com>
- Date: Fri, 12 Sep 2014 15:17:48 -0400
- Subject: Re: [PATCH 1/N] x86_64 vectorization support: vectorized math functions addition to Glibc
- Authentication-results: sourceware.org; auth=none
- References: <CAMXFM3t=ppndDUBzHzSus7xyuF5hTaLFZ5b273jD39NtddSvsw at mail dot gmail dot com> <Pine dot LNX dot 4 dot 64 dot 1409101549490 dot 12853 at digraph dot polyomino dot org dot uk> <6D39441BF12EF246A7ABCE6654B0235320F09D65 at LEMAIL01 dot le dot imgtec dot org> <20140911210246 dot GN23797 at brightrain dot aerifal dot cx> <87a9655rnu dot fsf at tassilo dot jf dot intel dot com>
On 09/12/2014 01:33 AM, Andi Kleen wrote:
> Rich Felker <dalias@libc.org> writes:
>>
>> This really seems like something the compiler should be doing --
>> translating parallelizable calls to the standard math functions into
>> calls to special simd versions (
>
> Of course gcc already supports that. Even in two different flavours.
>
> Not sure why the patch doesn't implement one of those ABIs though.
Please note that AFAIK gcc doesn't implement the ABI as documented
by Intel, but a variant, and my expectation is that we should *absolutely*
be targetting the gcc version of the Intel ABI otherwise what's the point?
> -mveclibabi=type
> Specifies the ABI type to use for vectorizing intrinsics
> using an external library.
> Supported values for type are svml for the Intel short vector
> math library and acml for
> the AMD math core library. To use this option, both
> -ftree-vectorize and
> -funsafe-math-optimizations have to be enabled, and an SVML
> or ACML ABI-compatible
> library must be specified at link time.
Cheers,
Carlos.