[RFC][PATCH LRA] WIP patch to fix one part of PR87507

[Peter Bergner]

On 10/19/18 4:16 PM, Peter Bergner wrote:
> Thoughts?  I'll note that this does not fix the S390 bugs, since those seem
> to be due to problems with early clobber operands and "matching" constraint
> operands.  I'm still working on that and hope to have something soon.
[snip]
> 	* lra-constraints.c (process_alt_operands): Abort on illegal hard
> 	register usage.  Prefer reloading non hard register operands.

I stand corrected.  Using this patch, plus Segher's combine patch, I am
able to bootstrap s390x-linux.  I'm running the test suite to see whether
that looks clean as well.  Maybe those s390 issues were related to combine
pushing hard regs into patterns and we just weren't handling them well?

Jeff, maybe once Segher commits his patch, can you give this patch a try
on your testers?

Peter