[Mesa-dev] [Mesa-stable] [PATCH] configure.ac: fix test for SSE4.1 assembler support

[Emil Velikov]

On 9 December 2015 at 05:37, Jonathan Gray <jsg at jsg.id.au> wrote:
> Change the __m128i variables to be volatile so gcc 4.9 won't optimise
> all of them out with -O1 or greater.  The _mm_set1_epi32/pinsrd calls
> still get optimised out but now there is at least one SSE4.1 instruction
> generated via _mm_max_epu32/pmaxud.  When all of the sse4.1 instructions
> got optimised out the configure test would incorrectly pass when the
> compiler supported the intrinsics and the assembler didn't support the
> instructions.
>
Must admit that I was not expecting that one. Looks like pixman (the
inspiration for this check) is missing volatile as well. Does that one
build/run fine on OpenBSD ?

> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91806
> Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
> Cc: "11.0 11.1" <mesa-stable at lists.freedesktop.org>
Reviewed-by: Emil Velikov <emil.velikov at collabora.com>

I'll pick this in a couple of days (barring any objections).

Thanks
Emil