[Mesa-dev] [PATCH 1/2] gallium: Enable aarch64 NEON CPU detection.

[Eric Anholt]

Matt Turner <mattst88 at gmail.com> writes:

> NEON (now called ASIMD) is available on all aarch64 CPUs. It seems that
> our code was missing an aarch64 path, leading to util_cpu_caps.has_neon
> always being false on aarch64. I think that means that the NEON tiling
> code in vc4 would not be enabled on aarch64 (vc4_load_lt_image_neon,
> etc).
> ---
> I have very little clue about aarch64 ABIs, so I don't know if there's
> another case that needs to be handled -- aarch32 maybe? Does
> PIPE_ARCH_AARCH64 just mean ARMv8 and so we should check something else
> for the ABI and choose Elf{32,64} based on that?

Do we actually need to do runtime detection?  It sounds like "standard"
armv8 is guaranteed NEON:

http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0024a/CEGDJGGC.html

For vc4, the aarch64 build uses neon in the _base version of the tiling
implementation.
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