The RPC implementation in LLVM is an adaptation of Jon's original state machine (see https://github.com/JonChesterfield/hostrpc). It looks very different at this point, but we collaborated on the initial design before I fleshed out everything else. Syscall or not is a bit of a semantic argument, but I lean more towards syscall 'inspired'.
The syscall layer this runs on was written at https://github.com/JonChesterfield/hostrpc, 800 commits from May 2020 until Jan 2023. I deliberately wrote that in the open, false paths and mistakes and all. Took ages for a variety of reasons, not least that this was my side project.
You'll find the upstream of that scattered across the commits to libc, mostly authored by Joseph (log shows 300 for him, of which I reviewed 40, and 25 for me). You won't find the phone calls and offline design discussions. You can find the tricky volta solution at https://reviews.llvm.org/D159276 and the initial patch to llvm at https://reviews.llvm.org/D145913.
GPU libc is definitely Joseph's baby, not mine, and this wouldn't be in trunk if he hadn't stubbornly fought through the headwinds to get it there. I'm excited to see it generating some discussion on here.
But yeah, I'd say the syscall implementation we're discussing here has my name adequately written on it to describe it as "my code".
My friend it's so incredibly bold of you to claim credit for this work when
1. Joe presented it
2. Joe's name is the only name on the git blame
3. I know Joe and I know he did the lion's share of the work
And so I'll repeat: Joe himself calls it rpc so I'm gonna keep calling it rpc and not syscall.