Re: [PATCH] rs6000: fmr gets used instead of faster xxlor [PR93571]

[Segher Boessenkool <segher@kernel.crashing.org>]

On Tue, Feb 21, 2023 at 06:00:52PM +0530, Ajit Agarwal wrote:
> On 21/02/23 4:34 pm, Segher Boessenkool wrote:
> > Please domn't use a switch, it isn't needed.  Instead use the "isa"
> > attribute (with p7v here), and put the preferred alternative first.
> 
> I am not sure how this is possible without switch and using only "isa".

You have the "p7v" "xxlor" alternative earlier than the "*" "fmr"
alternative.  You can have an "xxlor" for contraints "d", but probably
the best (and certainly the easiest) is to just move the existing
xxlor to before fmr.

Oh, the existing xxlor alternative is implicitly isa p7v, the "wa"
constraint causes that.  It may be nicer to mark it explicitly p7v as
well, nicer for the reader.

Btw, please update the other similar patterns at the same time?  There
are eight patterns with fmr in rs6000.md (the four in dfp.md should
probably not be touched); not all are similar so should be in separate
patches, if changed at all, but a bunch are completely analogous so
should not diverge.

(It is fine to first do this one pattern only, until we have worked out
all kinks, but all should be committed at the same time).

Thanks,


Segher