[Bug target/123829] New: early_ra should set ORIGINAL_REGNO and maybe REG_OFFSET

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123829

            Bug ID: 123829
           Summary: early_ra should set ORIGINAL_REGNO and maybe
                    REG_OFFSET
           Product: gcc
           Version: 16.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: pinskia at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64

For easier debug, ORIGINAL_REGNO should be set on the reg that early RA creates
for the hard register.

Most likely REG_OFFSET should be set but that increases memory usage as you
need REG_ATTRS.

I am going to do this but not until GCC 17.