Re: [committed] Convert xstormy16 to LRA

[Paul Koning <paulkoning@comcast.net>]

> On May 11, 2023, at 11:05 AM, Hans-Peter Nilsson via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> 
> ...
> Yes, very interesting.  Thank you for sharing this.  I've
> seen regressions with LRA for CRIS too, for
> "double-register-sized" types, which for CRIS, a 32-bit
> target, translates to 64-bit types (DFmode and DImode), and
> where LRA does a much worse job than reload; spills a lot
> more often to stack, even after trying every
> register-allocation-related hook I found (and also an LRA
> patch which helped only by a fraction, but regressed results
> on x86_64-linux, so let's quickly forget it again).

That observation makes me a bit worried.  While CRIS may not be a priority platform, that description makes it sound like a case that would be significant in any 32 bit platform, which would include priority ones like i386 and ARM.

If that's true, I wonder about dropping Reload.  While I understand it's been years since LRA was first introduced, wouldn't we even so want to go by the rule that a newer replacement mechanism doesn't replace an older one  until the replacement demonstrates comparable or better output compared with the older one?

	paul