On Tue, Oct 23, 2018 at 10:22:41PM +0000, Joseph Myers wrote: > On Tue, 23 Oct 2018, Michael Meissner wrote: > > > 2018-10-23 Michael Meissner <meiss...@linux.ibm.com> > > > > * config/rs6000/rs6000.c (TARGET_MANGLE_DECL_ASSEMBLER_NAME): > > Define as rs6000_mangle_decl_assembler_name. > > (rs6000_mangle_decl_assembler_name): If the user switched from IBM > > long double to IEEE long double, switch the names of the long > > double built-in functions to be <func>f128 instead of <func>l. > > [This is the issue discussed at the Cauldron of how to get the > redirections correct in any case that does not involve including the > standard <math.h> to get the function declarations.] > > My understanding was that __<func>ieee128 aliases would be added to glibc > (indeed, the relevant names are present in > sysdeps/ieee754/ldbl-128ibm-compat/Versions in glibc, albeit without > actually being enabled for powerpc64le yet), for two reasons: (a) to be > namespace-clean for standard C, and (b) because a few libm functions (and > many libc functions) have no _Float128 analogues but are still part of the > API for long double (e.g. the nexttoward functions, where nexttowardf, > nexttoward also need different versions for IEEE 128-bit long double, or > scalbl, which is somewhat obsolescent but still supported). > > Now, you can't use the __<func>ieee128 names with *current* glibc because > they aren't exported yet. So is the plan that GCC would later switch to > using the __<func>ieee128 names when available based on TARGET_GLIBC_MAJOR > and TARGET_GLIBC_MINOR (as more namespace-correct, and available for some > functions without <func>f128 variants), with use of <func>f128 only a > fallback for older glibc versions lacking __<func>ieee128?
I suspect the timing may not be right for GCC 9, since I tend to use the Advance Toolchain to get newer glibc's, and they are on 2.28. I just tried it, and as you said, they aren't exported yet. However, I am somewhat relunctant to do patches if I don't have a glibc that properly exports them. -- 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
