[Bug target/113484] Add support for _Float16 type on PowerPC

[john_platts at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113484

--- Comment #2 from John Platts <john_platts at hotmail dot com> ---
(In reply to Joseph S. Myers from comment #1)
> It would of course be necessary to define the ABI used for _Float16 (and
> _Complex _Float16) argument passing and return (in each PowerPC ABI for
> which we support use of this feature).

Should scalar _Float16 and _Complex _Float16 function parameters be first
passed in the F1-F13 registers on PPC, following the same rules as float,
double, _Complex _Float, and _Complex double function parameters (and with the
_Float16 function parameters that are passed into F1-F13 be converted to
double-precision floating point)?

Should a scalar _Float16 result be returned in the F1 register on PPC, with the
_Float16 result in the F1 register in double-precision floating point format
(but rounded to the precision and range of a _Float16)?