[Bug debug/81562] New: GDB cannot display long double register variable values

[sje at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81562

            Bug ID: 81562
           Summary: GDB cannot display long double register variable
                    values
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sje at gcc dot gnu.org
  Target Milestone: ---
              Host: aarch64-*-*
            Target: aarch64-*-*
             Build: aarch64-*-*

Created attachment 41837
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41837&action=edit
gdb.base/store.c test case

The GDB test case gdb.base/store.c fails with GCC 5.4.0 and above, it passes
with GCC 4.8.0.  If the register keyword is removed from the test case, it
works.

To reproduce the problem, compile store.c with -g, and do these gdb commands:

b wack_doublest
r
n
print l
print r

With GCC 4.8.0 both l and r can be printed (-1 and -2), with GCC 5.4.0 or
Top-of-tree (8.0), gdb will print l but say that r has been <optimized out>