[LLVMdev] supporting SAD in loop vectorizer

[Renato Golin]

On 4 November 2014 11:06, Das, Dibyendu <Dibyendu.Das at amd.com> wrote:
> Is there any plan to support special idioms in the loop vectorizer like sum of absolute difference (SAD) ? We see some useful cases where llvm is losing performance at -O3 due to SADs not being vectorized (hence PSADBWs not being generated).

It's been a while, but this could either be that the legalisation
phase is not recognising the reduction or that the cost is not taking
into account the lowered abs().

What does -debug-only=loop-vectorize say about it?

cheers,
--renato