[Bug target/95450] New: [10 regression] Wrong long double folding

["schwab@linux-m68k.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95450

            Bug ID: 95450
           Summary: [10 regression] Wrong long double folding
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: schwab@linux-m68k.org
  Target Milestone: ---
            Target: powerpc-*.*

$ cat test-float.c
#include <float.h>
#include <assert.h>

union gl_long_double_union
  {
    struct { double hi; double lo; } dd;
    long double ld;
  };

const union gl_long_double_union gl_LDBL_MAX =
  { { DBL_MAX, DBL_MAX / (double)134217728UL / (double)134217728UL } };
# undef LDBL_MAX
# define LDBL_MAX (gl_LDBL_MAX.ld)

int
main ()
{
  volatile long double m = LDBL_MAX;

  assert (m + m > m);
}
$ gcc -O2 test-float.c
$ ./a.out
a.out: test-float.c:20: main: Assertion `m + m > m' failed.
Aborted

test-float.c.234t.optimized contains:

  m ={v} 1.79769313486231580793728971405302307166001572487e+308;

but that evaluates to Inf.  DBL_MAX is
1.79769313486231570814527423731704e+308L.