Re: [PATCH, rs6000] Eliminate TARGET_CTZ,TARGET_FCTIDZ,FCTIWUZ defines

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

On Tue, Sep 20, 2022 at 05:01:53PM -0500, will schmidt wrote:
> On Tue, 2022-09-20 at 16:14 -0500, Segher Boessenkool wrote:
> > > TARGET_FCTIWUZ has a low number of uses, and can be directly
> > > replaced with TARGET_POPCNTD.
> > 
> > It is a p7 (ISA 2.06) insn.  Please make a TARGET_P7 or such?
> 
> Yes.  I do have a change later in the (unposted) series to replace
> POPCNTD with POWER7, at a glance thats #17 down the line. In review I
> agree with your comment that the in-between changes aren't the best
> choices. I'll see about skipping the in-between values and going
> straight for POPCNTD->POWER7.

First make new TARGET_Px and OPTION_MASK_Px for all "x" you want,
and do nothing else than enabling it in the respective CPUs in
rs6000-cpus.def .  This can be just one patch of course, it is
a) bloody simple and b) all is the same.  Have that as the very first
patch.  After that most things will be simple and obvious.  But please
do keep most later things split out, it is much easier to review.

> I am looking at the TARGET_POWER10 notation as the target style, versus
> TARGET_P7, but I can go that direction if we think that would be
> preferred.   Maybe it is since this is a retro-fix versus new. :-)

I think TARGET_P7 is a nicely shorter name.  It adds up :-)  The
existing TARGET_P10_SOMETHING do not write it out either btw (and same
for P9 and P8).

But this is not very important of course.  It helps to pick good names
from the get go of course, much less work than fixing things later.

> > (Don't let me dicsourage you btw, most is pretty straightforward).
> 
> Absolutely..   I do have this mostly covered locally, I just need to
> refine a few parts.  :-)

Looking forward to it!


Segher