[llvm-dev] ORC JIT Weekly #26 -- Orc library break-up, remote TargetProcessControl, and the beginnings of a runtime.

[Stefan Gränitz via llvm-dev]

One JIT-related news from my side: The regression bug
https://llvm.org/PR36209 in #LLDB was fixed last week, so source-level
debugging via GDB JIT Interface works again on current master when using
MCJIT plus ELF object file format.

The documentation update is still seeking review:
https://reviews.llvm.org/D90789
Preview:
https://weliveindetail.github.io/docs-pub/html/DebuggingJITedCode.html

Next steps will be:
* Double-check with LLJITWithGDBRegistrationListener example
* Consider adding a test case for LLJIT
* See what it takes to allow debugging for LLLazyJIT

If you have any feedback or questions on it, please let me know.

Best,
Stefan

On 16/11/2020 07:34, Lang Hames wrote:
> Hi All,
>
> I'm back again after a couple of weeks hiatus, and I have some good
> news for anyone interested in cross-process JITing with OrcV2: The
> remote TargetProcessControl and Orc library breakup patch has landed
> in 1d0676b54c4 [1]. Thanks very much to Dave Blaikie and Stefan
> Graenitz for all their feedback on the review!
>
> As described in my last email, this commit breaks the OrcJIT library
> into three pieces:
> - OrcJIT retains the bulk of the code.
> - OrcTargetProcess contains code only needed by JIT execution
> processes, and depends only on Support.
> - OrcShared contains code required by both of these libraries --
> mostly RPC and error types.
>
> For OrcV2 users who are running JIT'd code in-process the only
> essential change is that you will need to link against
> OrcTargetProcess library as well as OrcJIT. For users who want to JIT
> across processes/targets this library break-up means that your target
> process only needs to link against OrcTargetProcess, not LLVM's core
> or object libraries. 
>
> This patch also introduces a pair of
> classes, OrcRPCTargetProcessControl and OrcRPCTPCServer, that enable
> Orc-RPC based out-of-process execution. These classes serve two
> purposes: As an example of how to build cross-process
> TargetProcessControl implementations (for anyone who wants to build
> their own based on other XPC/IPC systems), and as a way to write
> regression tests for out-of-process execution without introducing new
> dependencies into LLVM.
>
> Anyone looking to try out the new APIs should check out llvm-jitlink,
> which has been updated to optionally use these new classes (see [2]
> for example usage). Once the API for OrcRPCTargetProcessControl
> settles down I plan to re-introduce Chapter 5 of the Building A JIT
> tutorial series to provide an introductory example for these APIs.
>
> The next step for Orc, required for both cross-process support and new
> features, is a runtime library. The runtime should be loadable via the
> JIT like any other static library, provide support for JIT re-entry
> (eventually replacing the existing Orc-ABI reentry code), thread
> locals, eh-frame and language runtime registration, execution of
> initializers, and more. I've started a prototype of a runtime as a
> library within compiler-rt in the orc-runtime-prototype branch of my
> llvm fork [3]. There's not much there yet, but I will keep you updated
> on my progress, and any questions, comments, or PRs are very welcome.
>
> Finally: I've added a skeleton roadmap to the OrcV2 design document
> [4], and plan to keep improving the documentation. I'd love to hear
> any specific requests you have for documentation improvements, as this
> will help me focus my efforts in this area. 
>
> -- Lang.
>
> [1] https://reviews.llvm.org/D90132 <https://reviews.llvm.org/D90132>
> [2] http://lists.llvm.org/pipermail/llvm-dev/2020-September/145070.html
> <http://lists.llvm.org/pipermail/llvm-dev/2020-September/145070.html>
> [3] https://github.com/lhames/llvm-project/tree/orc-runtime-prototype
> <https://github.com/lhames/llvm-project/tree/orc-runtime-prototype>
> [4] https://llvm.org/docs/ORCv2.html#roadmap
> <https://llvm.org/docs/ORCv2.html#roadmap>
>
-- 
https://flowcrypt.com/pub/stefan.graenitz@gmail.com

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