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Re: quad precision on PowerPC?
On 13 May 2011 13:19, Jonathan Wakely wrote:
> 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*)
>
It looks as though rs6000 and powerpc also support the
-mlong-double-128 option, although it's not documented