[BACKPORT] Apply fix for PR libgcc/97643 to gcc 10 branch

[Michael Meissner]

On Wed, Jan 20, 2021 at 06:46:14PM -0600, Segher Boessenkool wrote:
> On Wed, Jan 20, 2021 at 06:38:37PM -0500, Michael Meissner wrote:
> > This patch takes the fix that was applied to the trunk on December 3rd, and it
> > applies it to the GCC 10 branch.
> 
> > 	PR libgcc/97543, PR libgcc/97643
> > 	Backport from trunk.
> > 
> > 	2020-12-03  Michael Meissner  <meissner@linux.ibm.com>
> > 
> > 	* config/rs6000/t-linux (IBM128_STATIC_OBJS): New make variable.
> > 	(IBM128_SHARED_OBJS): New make variable.
> > 	(IBM128_OBJS): New make variable.  Set all objects to use the
> > 	explicit IBM format, and disable gnu attributes.
> > 	(IBM128_CFLAGS): New make variable.
> > 	(gcc_s_compile): Add -mno-gnu-attribute to all shared library
> > 	modules.
> 
> Okay for 10.  Thanks!
> 
> Is there a reason we do not have that testcase in the testsuite, btw?

In order to test it you need to build a compiler + toolchain where the default
long double is 64-bits.  So it is kind of hard to put in a test for it, since
it was a bug in how libgcc was built with a compiler that defaults to 64-bit
long double.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797