Re: port-arm/58789: aarch64 long double arithmetic is haunted

["Taylor R Campbell via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR port-arm/58789; it has been noted by GNATS.

From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
To: gnats-bugs%NetBSD.org@localhost, netbsd-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: port-arm/58789: aarch64 long double arithmetic is haunted
Date: Tue, 29 Oct 2024 18:52:50 +0000

 It seems the reason why the rintl1/rintl2 examples I gave get linked
 against libgcc_s is that libm pulls it in, via --as-needed -lgcc_s:
 
 $ grep -B2 libgcc_s libm.so.0.map
 As-needed library included to satisfy reference by file (symbol)
 
 libgcc_s.so.1                 libm_pic.a(s_tanl.pico) (__getf2@@GCC_3.0)
 ...
 
 (In netbsd-10, it's for __getf2 in csqrtl.pico.  __getf2 is the
 one-argument `tetra-float' (128-bit long double) greater-or-equal
 comparison function.)
 
 It is unclear to me why libm wants __getf2 out of libgcc_s, but not,
 say, __addtf3 (two-argument `tetra-float' add function), which is also
 defined in both libgcc_s and in libc.
 
 $ nm -gD --undefined-only libm.so.0 | grep -e __addtf3 -e __getf2
                  U __addtf3
                  U __getf2
 $ readelf -a libm.so.0 | grep -e __addtf3 -e __getf2
 000000060368  012300000402 R_AARCH64_JUMP_SL 0000000000000000 __addtf3@GCC_=
 3.0 + 0
 0000000605f8  01ea00000402 R_AARCH64_JUMP_SL 0000000000000000 __getf2@GCC_3=
 .0 + 0
    291: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __addtf3@GCC_3.0=
  (2)
    490: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __getf2@GCC_3.0 =
 (2)
   1210: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __addtf3@GCC_3.0
   1409: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __getf2@GCC_3.0
 
 Need a wizard to decipher this ancient elven lore...