port-powerpc/56899: powerpc long double confusion (gdb or libm wrong?)

[martin%NetBSD.org@localhost]

>Number:         56899
>Category:       port-powerpc
>Synopsis:       powerpc long double confusion (gdb or libm wrong?)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-powerpc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jun 23 14:15:00 +0000 2022
>Originator:     Martin Husemann
>Release:        NetBSD 9.99.98
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD big-apple.aprisoft.de 9.99.98 NetBSD 9.99.98 (POWERMAC_G5.MP) #56: Tue Jun 21 14:54:08 CEST 2022 martin%seven-days-to-the-wolves.aprisoft.de@localhost:/work/src/sys/arch/macppc/compile/POWERMAC_G5.MP macppc
Architecture: powerpc
Machine: macppc
>Description:

On powerpc we build libm without __HAVE_LONG_DOUBLE defined, as can
be seen here:
> nm /lib/libm.so.0.12 |fgrep fma
[..]
0001cde8 T fma
0001cde0 T fmaf
0001cde8 W fmal

... but on the other hand the in-tree gdb thinks we would support
long doubles:

(gdb) p sizeof(float)
$1 = 4
(gdb) p sizeof(double)
$2 = 8
(gdb) p sizeof(long double)
$3 = 16


>How-To-Repeat:
s/a

>Fix:
n/a