[all-commits] [llvm/llvm-project] 75b7b9: [libc][rpc] Update locking to work on volta

[Jon Chesterfield via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 75b7b9f292f7842606d3a7111465dced59b22ba2
      https://github.com/llvm/llvm-project/commit/75b7b9f292f7842606d3a7111465dced59b22ba2
  Author: Jon Chesterfield <jonathanchesterfield at gmail.com>
  Date:   2023-05-04 (Thu, 04 May 2023)

  Changed paths:
    M libc/src/__support/CPP/atomic.h
    M libc/src/__support/GPU/amdgpu/utils.h
    M libc/src/__support/GPU/generic/utils.h
    M libc/src/__support/GPU/nvptx/utils.h
    M libc/src/__support/RPC/rpc.h
    M libc/src/__support/RPC/rpc_util.h

  Log Message:
  -----------
  [libc][rpc] Update locking to work on volta

Carefully work around not knowing the thread mask that nvptx intrinsic
functions require.

If the warp is converged when calling try_lock, a single rpc call will handle
all lanes within it. Otherwise more than one rpc call with thread masks that
compose to the unknown one will occur.

Reviewed By: jhuber6

Differential Revision: https://reviews.llvm.org/D149897