[LLVMdev] Enabling the SLP vectorizer by default for -O3

Renato Golin renato.golin at linaro.org
Mon Jul 15 06:48:16 PDT 2013

Hi Nadav,

I think it's a great idea to have the slp vectorizer enabled, but maybe we
should trim the horrible cases first (regressions, +5% compile time, etc).
I don't mind sub-5% compile-time increase in O3, nor I mind sub-1%
regressions in performance on some benchmarks IFF the majority of the
benchmarks improve.

On 15 July 2013 06:55, Nadav Rotem <nrotem at apple.com> wrote:

> I suspected that the problem is the movupd's that load xmm0 and xmm1.

I've seen this before on ARM, and I agree, it looks like the load is
constrained by some other condition or pipeline stall before that.

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