[LLVMdev] LLVM ARM VMLA instruction

[Renato Golin]

On 18 December 2013 12:31, Tim Northover <t.p.northover at gmail.com> wrote:

> That's what I thought! But we do seem to generate vfma on Cortex-A9.
> Wonder if that's a bug, or Cortex-A9 is "VFPv3, but chuck in vfma
> too"?
>

Hi Tim,

I believe that's the NEON VMLA, not the VFP one. There was a discussion in
the past about not using NEON and VFP interchangeably due to IEEE
assurances (which NEON doesn't have), but the performance gains are too
big. I think the conclusion is to only use NEON instead of VFP (when
they're semantically similar) when -unsafe-math is on.

cheers,
--renato
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