On Fri, Jul 06, 2018 at 10:16:34AM -0300, Tulio Magno Quites Machado Filho
wrote:
> I suggest to test with the following program:
>
> #include <math.h>
>
> int
> main ()
> {
> return !isinfl(__builtin_infl());
> }
>
> Build it with:
> gcc -mabi=ieeelongdouble -fno-builtin -Wno-psabi -lm test-ldbl.c
>
> If the execution of the program returns 0, your math library supports IEEE
> long
> double.
Thanks, but I suspect that it won't work for building cross compilers or for
building where the compiler built uses the Advance Toolchain libraries and
shared library loader instead of the system versions using the configuration
option --with-advance-toolchain=atx.y.
The issue is you need to test whether the target GLIBC has the support when
configuring the compiler, but if you are building for a cross target, you can't
run the resulting binary. Even on a native system, with options like
--with-advance-toolchain and --with-sysroot, the libraries used by the host
compiler used to build stage1 of GCC might be different from the libraries used
to build the target compiler (or stage2/stage3 in a bootstrap native build).
So I used the GLIBC version tests that were already part of the GCC
configuration.
If there is a simple method that works for cross compilers or where a specified
sysroot is used, it would be simpler than having version checks.
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.ibm.com, phone: +1 (978) 899-4797
