Richard Biener wrote:
scalar_reduc_to_vector misses a comment.
Ok to reuse the comment in optabs.h in optabs.c also?
I wonder if at the end we wouldn't transition all backends and then renaming reduc_*_scal_optab back to reduc_*_optab makes sense.
Yes, that sounds like a plan, the _scal is a bit of a mouthful.
The optabs have only one mode - I wouldn't be surprised if an ISA invents for example v4si -> di reduction? So do we want to make reduc_plus_scal_optab a little bit more future proof (maybe there is already an ISA that supports this kind of reduction?).
That sounds like a plausible thing for an ISA to do, indeed. However given these names are only used by the autovectorizer rather than directly, the question is what the corresponding source code looks like, and/or what changes to the autovectorizer we might have to make to (look for code to) exploit such an instruction. At this point I could go for a reduc_{plus,min_max}_scal_<mode><mode> which reduces from the first vector mode to the second scalar mode, and then make the vectorizer look only for cases where the second mode was the element type of the first; but I'm not sure I want to do anything more complicated than that at this stage. (However, indeed it would leave the possibility open for the future.)
--Alan
