[Bug target/85657] New: Make __ibm128 a separate type, even if long double uses the IBM double-double format

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85657

            Bug ID: 85657
           Summary: Make __ibm128 a separate type, even if long double
                    uses the IBM double-double format
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

Part of the issue with PR target/85075 is that the __ibm128 type was
implemented internally as long double, when the long double type is IBM
double-double (i.e. the same bit representation as __ibm128).

Once __ibm128 is a separate type, then the restriction against not using
-mlong-double-64 with __ibm128 goes away.

Finally, there should a version of pack and unpack that targets __ibm128 as
well.