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
