svn commit: r339350 - head/contrib/elftoolchain/elfcopy

[Ed Maste]

On Mon, 15 Oct 2018 at 07:13, Ed Maste <emaste at freebsd.org> wrote:
>
> Hi Antoine, did you bisect to this rev or does it just look like the
> most probable candidate? Can you copy a pair of differing .o files
> (say, gcc/cc1plus-checksum.o) from the work dir to freefall?

Antoine provided a tarball of the work dir to me, and pointed out that
the *-checksum.o files are not interesting - they are warnings only
and are present prior to the identified change.

Comparing one of the other differing files, e.g.
stage{2,3}-gcc/expmed.o, demonstrates the problem. Gcc's build
machinery is reasonably obfuscated so I'm not sure of the exact set of
operations, but I can infer that the stage2/stage3 comparison is
running strip on the object files and then comparing the result. Gcc
is encountering this part of my strip/objcopy change:

> Stripping binaries with relocations
> referencing removed symbols was already broken, and after this change
> may still be broken in a different way.

Stripping symbols and relocations from an object file is not a
particularly useful operation, since the object then can't be linked
or otherwise used. But it seems Gcc's stage comparison relies on this.
I did try running "strip --strip-debug" on stage{2,3}-gcc/expmed.o (a
reasonable operation on object files) and that produced identical
output.

It may well be that a further change to ELF Tool Chain's strip is
warranted, but I suspect the most straightforward and reliable fix
here will be to just have gcc use GNU strip.