[llvm-dev] Debugging JIT'ed code with ORC JIT?

[Yichao Yu via llvm-dev]

> What debugging support MCJIT has is provided by the RuntimeDyld utility,
> which ORC shares. I would expect anything in that document to apply to ORC
> as well, though I haven't tested it personally.

I'm pretty sure that's not the case, at least not with any simple
orcjit tutorials I've seen.

The GDB support is provided by `GDBJITRegistrationListener` which is
registered to MCJIT directly in the constructor and AFAICT no where
else. Also, since there doesn't seem to be a default (non-noop)
implementation of `ExecutionEngine::RegisterJITEventListener` I
believe you can't just call `RegisterJITEventListener` on non-MCJIT
and expect it to work.

So while I totally believe one can use
`JITEventListener::createGDBRegistrationListener()` to hook the JIT
with the the gdb registration function, it won't work without writing
code to explicitly do that (in additional to actually writing code to
interface with the event listener directly). OTOH though when using
MCJIT, this is done by default and one don't need to write any code
for it to work.

>
> For what it's worth, this is something I'm interested in and hope to make
> some progress on in tree in the not too distant future.
>
> -- Lang.
>
> On Mon, Oct 9, 2017 at 12:27 PM, Jameson Nash via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>>
>> That is correct – there is no built-in support. You have to provide your
>> own Registrar to the ObjectLinkingLayer to provide this sort of
>> functionality. (For example JuliaLang does that at
>> https://github.com/JuliaLang/julia/blob/1216e5f60cd2b23e29856b5227399ab0f3abef76/src/jitlayers.cpp#L437,
>> in addition to registering the function pointer and object file info in
>> several other places).
>>
>>
>> On Sun, Oct 8, 2017 at 11:48 PM Connor Gray via llvm-dev
>> <llvm-dev at lists.llvm.org> wrote:
>>>
>>> Hi,
>>>
>>> I’m wondering if it’s possible to debug code JIT’ed with the newer ORC
>>> JIT. The LLVM documentation has a page at
>>>
>>>     llvm.org/docs/DebuggingJITedCode.html
>>>
>>> showing an example of using gdb to debug MCJIT’ed code, but has no
>>> mention of ORC JIT.
>>>
>>> From searching around online I’ve gotten the impression that ORC JIT does
>>> *not* support providing debugging information to attached debuggers, but no
>>> definitive source. Is it the case that ORC JIT in fact does support
>>> debugging, and if so, are there examples available; or is my initial
>>> impression correct?
>>>
>>> Thanks,
>>> Connor
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
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>
>
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