quad precision on PowerPC?

[Jonathan Wakely]

On 13 May 2011 11:20, Vincent Lefevre wrote:
> On 2011-05-13 11:38:22 +0200, Axel Freyn wrote:
>> Hi Vincent,
>> On Fri, May 13, 2011 at 11:29:46AM +0200, Vincent Lefevre wrote:
>> > https://www-304.ibm.com/support/docview.wss?rs=2030&uid=swg21245006
>> > says:
>> >
>> >     GCC versions 4.0 and higher support 128-bit quad precision
>> >     floating point values. The XL compilers now provide the
>> >     -qfloat=gcclongdouble option to be compatible with GCC's
>> >     representation of 128-bit quad precision floating point
>> >     values.
>> >
>> > Anyone knows how to enable it?
>> >
>> > By default, I just get the double-double representation (yielding
>> > 106-bit precision).
>> the gcc online-docs say
>> http://gcc.gnu.org/onlinedocs/gcc/Floating-Types.html
>> "Not all targets support additional floating point types. __float80 and
>> __float128 types are supported on i386, x86_64 and ia64 targets."
>> (but I never tried it on PowerPC)
>
> Still, __float128 isn't a long double as said in the note above.
> I now wonder whether the note is correct.

Use --with-long-double-128 at configure time.

See gcc/configure

case "$target" in
  powerpc*-*-linux* | \
  powerpc*-*-gnu* | \
  sparc*-*-linux* | \
  s390*-*-linux* | \
  alpha*-*-linux*)