[llvm-dev] Embedding LLD version to executables

[Dave Bozier via llvm-dev]

Hi,

> Scenario 1: you added -fuse-ld=lld to your command line, but you are
suspecting that the option is ignored. Currently, it's actually
surprisingly hard to tell if an output was created by LLD.

Can't you use -v to see what linker the compiler driver invoked?


On Wed, Oct 19, 2016 at 4:41 AM, Rui Ueyama via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> On Tue, Oct 18, 2016 at 8:22 PM, Mehdi Amini <mehdi.amini at apple.com>
> wrote:
>
>>
>> > On Oct 18, 2016, at 6:44 PM, Rui Ueyama via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>> >
>> > I'd like to make LLD embed version information so that we can determine
>> if an executable was created by LLD and if that's the case which version of
>> LLD.
>>
>> Pardon my ignorance, but what’s the motivation?
>>
>
> It should make trouble shooting linker issues easier. Here are a few
> scenarios.
>
> Scenario 1: you added -fuse-ld=lld to your command line, but you are
> suspecting that the option is ignored. Currently, it's actually
> surprisingly hard to tell if an output was created by LLD.
>
> Scenario 2: someone reported an issue about an executable linked by LLD,
> and we know that version X has a similar bug, then the first thing we want
> to do is to check if the executable was created with version X.
>
>
>>
>> We don’t embed the clang version in every binary clang generates for
>> instance.
>>
>> >
>> > ld.bfd doesn't seem to embed any information, so we cannot tell whether
>> an executable was linked by ld.bfd or not easily.
>> >
>> > ld.gold embeds a string "GNU gold <version>" as
>> ".note.gnu.gold-version" section contents.
>> >
>> > I'm wondering what we should do for LLD. The gold's way seems almost
>> right, but I think we don't want to use the same section name because it
>> contains "gold" as part of the section name. However, at the same time, I
>> don't believe we want to create ".note.gnu.lld-version", because if we do,
>> all programs that determine linker version need to look at
>> ".note.gnu.<linker-name>-version" for all known linkers. That's absurd.
>> (Also, our product is not GNU, so ".gnu" part is probably irrelevant.)
>> >
>> > I'm leaning towards ".note.linker-version" in hope that other linkers
>> follow it.
>>
>> At least that would look much better than a .gnu.xxxx
>>
>> —
>> Mehdi
>>
>>
>>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20161019/71783353/attachment.html>