[llvm-dev] RFC: Generic IR reductions

Amara Emerson via llvm-dev llvm-dev at lists.llvm.org
Wed Feb 1 06:56:52 PST 2017

+CC Chandler and Philip.

On 1 February 2017 at 08:27, Renato Golin <renato.golin at linaro.org> wrote:

> Well, that was certainly a smaller group than the list. Design
> decisions should not be taken off list, so we must have this
> discussion on the list again, I'm afraid.
>> I don't believe having many intrinsics would be a problem.
> This is against every decision I remember. Saying it out loud in a
> meeting is one thing, writing them down and implementing and having to
> bear the maintenance costs is another entirely.

That's fair. To bring some context, during Elena's BOF
Chandler/Philip's made some arguments against the idea of general
purpose single intrinsics that take an opcode parameter, which went
along the lines of: the design would lower the bar for introducing new
idioms to an extent that each one would not have to undergo as much
scrutiny as separate additions. I specifically recall someone, and I
think it was Chandler but correct me if I'm wrong, saying that many
intrinsics were not in itself a problem. Their points were also
broader than that of reductions, and covered the general approach of
handling groups of idioms. Chandler/Philip I hope I haven't
mischaracterized your thoughts.


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