[PATCH] [SLPVectorization] Vectorize Reduction Chain feeding into a 'return' statement

James Molloy james at jamesmolloy.co.uk
Wed Nov 12 09:15:01 PST 2014


Hi,

Don't get me wrong, I'm not trying to torpedo it or anything. It's fine by
me to go in. I'd just like to raise awareness that there's a greater
problem that this doesn't seem to go towards solving.

Sorry if I came across like a complainer :

James
On Wed, 12 Nov 2014 at 16:41 Arnold Schwaighofer <aschwaighofer at apple.com>
wrote:

> I see this as an intermediate step that will allow us to catch certain
> patterns. If performance tests show it is beneficial why not take it?
>
> Enabling horizontal reductions is a second step that might subsume this
> logic.
>
>
> On Nov 12, 2014, at 8:33 AM, James Molloy <james at jamesmolloy.co.uk> wrote:
>
> Hi,
>
> This seems to me to be a sticking plaster over a bigger problem. This will
> fix some reductions, but the bigger problem of loops being unrolled and
> then not optimised still exists. I'd much prefer to see a solution to this
> problem than just adding more Elastoplast-logic to SLP.
>
> James
> On Wed, 12 Nov 2014 at 16:24 hfinkel at anl.gov <hfinkel at anl.gov> wrote:
>
>> ================
>> Comment at: test/Transforms/SLPVectorizer/X86/return.ll:58
>> @@ +57,3 @@
>> +
>> +attributes #0 = { nounwind readonly "less-precise-fpmad"="false"
>> "no-frame-pointer-elim"="false" "no-infs-fp-math"="false"
>> "no-nans-fp-math"="false" "stack-protector-buffer-size"="8"
>> "unsafe-fp-math"="false" "use-soft-float"="false" }
>> +
>> ----------------
>> Please remove unnecessary attributes.
>>
>> ================
>> Comment at: test/Transforms/SLPVectorizer/X86/return.ll:62
>> @@ +61,3 @@
>> +
>> +!0 = metadata !{metadata !"clang version 3.6.0 (221134)"}
>> +!1 = metadata !{metadata !2, metadata !2, i64 0}
>> ----------------
>> Please remove unnecessary metadata.
>>
>> http://reviews.llvm.org/D6227
>>
>>
>>
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>
>
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