[cfe-dev] Xray with shared libraries?

[Steve Lesser via cfe-dev]

Hi Dean,

Thank you for the explanation.

I'm happy to get involved getting runtime patching of shared libraries into
XRay. I'm new to clang / llvm contribution so I'm sure there will be some
ramp up- it will be very helpful to collaborate to ease in. Please let me
know what is the best way of catching up on the latest explorations /
investigation of XRay with shared libraries.

Cheers,
Steve

On Tue, Aug 28, 2018 at 11:14 AM Dean Michael Berris <dean.berris at gmail.com>
wrote:

> Hi Steve,
>
> On Tue, 28 Aug 2018 at 8:00 am, Steve Lesser via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
>> Hi all,
>>
>> I have been unsuccessfully trying to use Xray with shared libraries
>> following the instructions on https://llvm.org/docs/XRay.html . When
>> compiling and linking binaries such as a google test runner with
>> '-fxray-instrument' I get results from any code built from the executable
>> itself, but code from shared libraries also built with '-fxray-instrument'
>> never appear in the results. This is all in C++, linux, x86_64
>>
>> I don't see any references to restrictions or special set up for shared
>> libraries in the docs, but I see one mention in
>> https://reviews.llvm.org/D38226 saying
>>
>> 'The XRay runtime currently doesn't support dynamic registration of
>> instrumentation sleds in shared objects, which we'll start enabling in
>> the future. That work has to happen in the back-end and in the runtime.'
>>
>> Does this mean Xray with shared libraries is unsupported at this time?
>>
>
> Yes, unfortunately we don’t support runtime patching of shared libraries
> yet. There were some explorations early on with how to get that working and
> integrated in the runtime, but that work has stalled.
>
> Martin was looking at making that happen a while back, but we’ve gotten
> sidetracked with other things in the meantime.
>
> I’d be happy to review proposals and patches, and we have some ideas to
> what might work here. If you’re interested in exploring the options and/or
> making contributions to get that working, I’d be happy to collaborate.
>
> Cheers
>
> --
> Dean
>
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