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Re: [PATCH, vec-tails 07/10] Support loop epilogue combining
On 07/22/2016 05:36 AM, Richard Biener wrote:
The thing that needs work I think is re-running of if-conversion.
I wonder if we could revamp if-conversion to work on a subset of the
CFG? I can see that potentially being useful in other contexts. Would
that work for you Richi?
We've already got Bin doing that for DOM...
Also I don't like at
all that we have many variants of vectorizing but somehow the decision which one
to choose is rather unclear. The way the epilogue vectorization code
is hooked in
is rather awkward and bound to be a maintainance burden (well, maybe a
small one).
I think it's going to be a small one. I suspect that we really need
another architecture with masking capabilities to really be able to see
how the costing models ought to work and bring sanity to that decision.
And last, I double there is a case for a masked vectorized loop - I can bet that
doing a non-masked vectorized loop plus a masked epilogue (with no iteration
then!) will be always faster unless you hit the window of very few iterations
(or optimizing for size - in which case vectorizing is questionable on
its own and
disabled IIRC).
Ilya, does this case make a noticeable difference with the ICC
implementation?
Jeff