Re: [PATCH][RS6000] Fix PR87870: ppc64 generates poor code when loading constants into TImode vars

[Michael Meissner <meissner at linux dot ibm dot com>]

On Fri, Nov 16, 2018 at 01:33:58PM -0600, Peter Bergner wrote:
> On 11/16/18 11:06 AM, Segher Boessenkool wrote:
> > Why does the "r" have a "*"?  Should it have been just a "?"?
> 
> Maybe Mike remembers why he added it?  I'd guess it was probably to
> try and steer the vector modes away from GPRs.  However, since that
> alternative was also suppose to handle TImode, "*" is probably not
> what we want for that.  The constraint for the new combines alternative
> uses a mode iterator so that the vector modes use "??r" while TImode
> uses "r".  I think that is what we want.

I imagine when I made the original change we had a different move for TImode
(and the -mvsx-timode hack) than for vector modes.  And it was likely pre-LRA
also.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797