[Bug binutils/24326] `nm` outputs symbol values of 0 for ft LTO object files

[brandon.m.simmons at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=24326

--- Comment #6 from Brandon Simmons <brandon.m.simmons at gmail dot com> ---
Ah, okay now we're getting somewhere. So it seems that the issue is related to
the liblto plugin (which AIUI is enabled either by using gcc-nm, or by putting
the plugin in the right place). So I think we may be observing the same
behavior:

My `nm` is not `gcc-nm`:

jberryman /tmp » file $(which nm)                                              
                                   130 ↵
/usr/bin/nm: symbolic link to x86_64-linux-gnu-nm
jberryman /tmp » file $(which x86_64-linux-gnu-nm)
/usr/bin/x86_64-linux-gnu-nm: ELF 64-bit LSB shared object, x86-64, version 1
(SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for
GNU/Linux 2.6.32, BuildID[sha1]=92954b72bc19e08b152f66b7a1ce5fb10d01f33c,
stripped
jberryman /tmp » file $(which gcc-nm)
/usr/bin/gcc-nm: symbolic link to gcc-nm-6
jberryman /tmp » file $(which gcc-nm-6)
/usr/bin/gcc-nm-6: symbolic link to x86_64-linux-gnu-gcc-nm-6
jberryman /tmp » file $(which x86_64-linux-gnu-gcc-nm-6)
/usr/bin/x86_64-linux-gnu-gcc-nm-6: ELF 64-bit LSB executable, x86-64, version
1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for
GNU/Linux 2.6.32, BuildID[sha1]=c042db1fc5f0c6375e2af5c34f1103d5f02233af,
stripped

...but I DO have the plugin symlinked. So if I do:

    $ rm /usr/lib/bfd-plugins/liblto_plugin.so

I find `nm` gives me same output as you see:

    jberryman /tmp » nm mytemp.o.ltofat                                         
    0000000000000034 C constantBAR
    0000000000000012 C constantFOO
    0000000000000001 C __gnu_lto_v1

Likewise same as you for non-fat lto object.

And to be clear I'm not sure this is a bug (I'm pretty out of my depth), but
it's behavior that caused an error in a big complicated OSS compiler project
that I'm just starting to try to contribute to.

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