[llvm-dev] ORC JIT Weekly #40 -- Out with Orc RPC, In with SimpleRemoteEPC.

[Lang Hames via llvm-dev]

Hi All,

Since the last update all in-tree tools and examples that support remote-JITing have been moved from OrcRPCExecutorProcessControl (and the older OrcRemoteTarget* APIs) to SimpleRemoteEPC. SimpleRemoteEPC, compared to earlier APIs, should be both easier to use and adapt, and better at error handling and recovery.

You can check out an example use of SimpleRemoteEPC in the llvm-jitlink tool, in the Session::Create method [1]. In that method the "if" sequence constructs the ExecutorProcessControl object to be used, using a SimpleRemoteEPC instance for remote executors (in the -oop-executor or -oop-executor-connect case). By writing the llvm-jitlink tool against the ExecutorProcessControl API these few lines are all that it takes to dynamically select in-process or out-of-process JITing.

The corresponding server-side code can be found in the llvm-jitlink-executor tool's main method [2]. 

The switch to SimpleRemoteEPC has allowed us to remove all in-tree users of the ORC RPC system, two of the more complicated JITLinkMemoryManager implementations, and the ORC RPC system itself. All up ~6.5k SLOC were removed in this process. Removing this legacy code should unblock progress on the JITLinkMemoryManager refactor -- I hope to have an update on that effort for you next week.

-- Lang.

[1] https://github.com/llvm/llvm-project/blob/5f7a5353301b776ffb0e5fb048992898507bf7ee/llvm/tools/llvm-jitlink/llvm-jitlink.cpp#L814

[2] https://github.com/llvm/llvm-project/blob/bdb5aa65b1b557865a64860121c9376937e30984/llvm/tools/llvm-jitlink/llvm-jitlink-executor/llvm-jitlink-executor.cpp#L158