[Bug target/99197] New: Built-ins for packing/unpacking __ibm128 not documented

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99197

            Bug ID: 99197
           Summary: Built-ins for packing/unpacking __ibm128 not
                    documented
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Keywords: documentation
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---
            Target: powerpc*-*-*

https://gcc.gnu.org/onlinedocs/gcc/Basic-PowerPC-Built-in-Functions-Available-on-all-Configurations.html
has the prototypes:

double __builtin_unpack_ibm128 (__ibm128, int);
__ibm128 __builtin_pack_ibm128 (double, double);

But they are undocumented.

The simplest fix might be to just point to the next section of the docs and say
they behave the same as the corresponding __builtin_xxx_longdouble built-ins.