[Pixman] [PATCH v2 2/3] build: use '-mloongson-mmi' for Loongson MMI.

Adam Jackson ajax at redhat.com
Fri Feb 21 15:32:38 UTC 2020

On Thu, 2020-02-20 at 22:23 +0800, Yin Shiyou wrote:
> It's suggested to use '-mloongson-mmi' to enable MMI.
> To keep compatible with old processor, '-mloongson-mmi' will be
> setted for Loongson-3A only.

The pattern we've used for other CPUs is to build support for as many
ISA extensions as possible, unless they are explicitly disabled.
Distributions tend to want to set their own minimum ISA levels, and if
they wanted to assert -mloongson-mmi they would already have added it
to CFLAGS globally.

Do you have any performance data for this change?

If setting -mloongson-mmi means the compiler can do useful
autovectorization, then that's probably true for other arches too (eg
amd64 vs avx2), and we should support this kind of thing more
generically. But as it stands I don't think this patch is a good idea.

- ajax

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