Could you send me an example .o file that reproduces the issue? I'm curious now.
-- adrian > On Mar 15, 2024, at 7:41 AM, John DelSignore <jdelsign...@perforce.com> wrote: > > Hi Adrian, > > Thanks for the reply. As far as I can tell, neither gcc nor gfortran produce > N_SO stabs when -gdwarf-4 is used. It is the Apple ld-classic linker that is > generating the N_SO stabs and inserting them into the Mach-O nlist symbol > table. I believe that the linker is reading the DWARF information out of the > object file and using the compilation unit DIE to determine the string values > for the N_SO stabs. > > In the newest set of Apple ld sources I could find, I can see that the > following function in OutputFile.cpp generates N_SO and N_OSO stabs: > > void OutputFile::synthesizeDebugNotes(ld::Internal& state) > > and seems to be using the DWARF information. > > My guess is that there is something about the way gcc and gfortran generate > the compilation unit DIE that causes the linker to generate: > > N_SO > <compilation-directory><random-control-character><directory-path-of-file-name> > N_SO <basename-of-file-name> > > For example: > > dc3-mac-tvt4 39 03/15 10:38 /tmp % gcc-mp-13 -gdwarf-4 ~/hello.c -c > dc3-mac-tvt4 40 03/15 10:38 /tmp % gcc-mp-13 hello.o -o hello > dc3-mac-tvt4 41 03/15 10:39 /tmp % nm -ap hello | cat -v | grep -F ' SO ' > 0000000000000000 - 01 0000 SO > 0000000000000000 - 00 0000 SO /tmp/^L/nfs/homes/jdelsign/ > 0000000000000000 - 00 0000 SO hello.c > 0000000000000000 - 01 0000 SO > 0000000000000000 - 00 0000 SO > /opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_lang_gcc13/gcc13/work/build/x86_64-apple-darwin23/libgcc/^A/opt/local/var/macports/build/_opt_bblocal_var_buildworker_ports_build_ports_lang_gcc13/gcc13/work/gcc-13.2.0/libgcc/ > 0000000000000000 - 00 0000 SO emutls.c > 0000000000000000 - 01 0000 SO > dc3-mac-tvt4 42 03/15 10:39 /tmp % > > Notice that the control characters in two "first" SO stabs. > > Do you agree this is a linker bug? > > Thanks, John D. > > On 3/14/24 14:34, Adrian Prantl wrote: > >> The N_OSO stabs entries are indeed added by the linker >> (https://wiki.dwarfstd.org/Apple's_%22Lazy%22_DWARF_Scheme.md). >> Having done a quick scan through the linker sources I was not able to >> pinpoint the place where this path concatenation is happening. >> >> > FWIW, I have not seen a similar problem with Apple's "cc", which is clang >> > compiler. It does not generate the working directory in the N_SO stabs: >> >> Assuming that that is indeed the root cause, it might be best to modify >> gfortran to no longer emit N_SO stabs entries in the object file. >> >> Adrian >> >> >> >> >> CAUTION: This email originated from outside of the organization. Do not >> click on links or open attachments unless you recognize the sender and know >> the content is safe. >> > > This e-mail may contain information that is privileged or confidential. If > you are not the intended recipient, please delete the e-mail and any > attachments and notify us immediately. > >
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