On Fri, Feb 10, 2017 at 9:14 PM, Jerry DeLisle <jvdeli...@charter.net> wrote: > On 02/09/2017 08:05 PM, Steve Kargl wrote: >> >> On Thu, Feb 09, 2017 at 07:35:11PM -0800, Jerry DeLisle wrote: >>> >>> On 02/09/2017 12:40 PM, Janne Blomqvist wrote: >>>> >>>> On Thu, Feb 9, 2017 at 8:33 PM, Steve Kargl >>>> <s...@troutmask.apl.washington.edu> wrote: >>>>> >>>>> On Thu, Feb 09, 2017 at 12:10:02PM +0200, Janne Blomqvist wrote: >>>>>> >>>>>> >>>>>> That being said, I think even with Steve's patch, it's not guaranteed >>>>>> to give you IEEE 754-2008 binary128. E.g. on IBM POWER targets, >>>>>> depending on the ABI you may get an IBM extended double (double-double >>>>>> or __ibm128) format. Although if IEEE binary128 is also available, >>>>>> with Steve's patch you should get that one has it has more precision >>>>>> that __ibm128. >>>>> >>>>> >>>>> I do not have to a IBM POWER system, so cannot easily check the >>>>> effect of my patch. >>> >>> >>> On IBM Power >>> >>> program foo >>> use iso_fortran_env >>> REAL(REAL128) x >>> print '(3(I0,1X))', kind(x), digits(x), precision(x) >>> end program foo >>> >>> $ gfc -static foo.f90 >>> $ ./a.out >>> 16 106 31 >>> >> >> That is the double-double format. The gcc manual says that >> powerpc takes a -mfloat128 option (among others). This will >> probably give you 16 113 33. >> > > $ gfc -static -mfloat128 foo.f90 > > $ ./a.out > 16 106 31
Hmm, fascinating. What about -mfloat128 -mcpu=power9 -mfloat128 -mabi=ieeelongdouble -mfloat128 -mcpu=power9 -mabi=ieeelongdouble ? (see https://gcc.gnu.org/wiki/Ieee128PowerPC for details) -- Janne Blomqvist
