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Re: PR83004: Accidental change to pr81136.c for VECTOR_BITS==128
- From: Richard Sandiford <richard dot sandiford at linaro dot org>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Richard Biener <richard dot guenther at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 22 Nov 2017 14:17:59 +0000
- Subject: Re: PR83004: Accidental change to pr81136.c for VECTOR_BITS==128
- Authentication-results: sourceware.org; auth=none
- References: <8760a21wzd.fsf@linaro.org> <CAFiYyc1NGYD6uJQFxabOh_-U0eGmhDLjFLEt_MZ5FdYieNfj6w@mail.gmail.com> <20171122140346.GV14653@tucnak>
Jakub Jelinek <jakub@redhat.com> writes:
> On Wed, Nov 22, 2017 at 02:51:09PM +0100, Richard Biener wrote:
>> On Wed, Nov 22, 2017 at 10:30 AM, Richard Sandiford
>> <richard.sandiford@linaro.org> wrote:
>> > r254589 was supposed to leave tests unchanged for the default setting
>> > of VECTOR_BITS, but I must have got my sums wrong on pr81136.c.
>> > Sorry for the breakage.
>> >
>> > Tested on aarch64-linux-gnu, x86_64-linux-gnu and powerpc64le-linux-gnu,
>> > OK to install?
>>
>> Ok.
>
> That will still FAIL e.g. with -march=skylake-avx512 or -march=knl
> (at least when not preferring 256 or 128 bit vectors), those would need
> ALIGNMENT 64.
Yeah, the real fix for AVX512 is to define VECTOR_BITS. And I'd have
thought even AVX2 would need to define it to get clean results on other
tests. But the patch that introduced VECTOR_BITS just wasn't supposed
to be changing the default behaviour in the way that I'd accidentally
done here.
Do you know what the vect.exp results are like for 256-bit and 512-bit
vectors on x86_64? Like I said in the PR, I was surprised we were the
first to hit the need for a macro like VECTOR_BITS. The results for
-msve-vector-bits=256 and -msve-vector-bits=512 were really poor without
it, since many things were hard-coded to values that made sense for
<= 128-bit (or sometimes <= 256-bit) vectors.
Thanks,
Richard