[all-commits] [llvm/llvm-project] d5ab24: Omit atomic_{, un}signed_lock_free if unsupported

[androm3da via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d5ab243c6f79f881121a80487f0879d2ab0acc41
      https://github.com/llvm/llvm-project/commit/d5ab243c6f79f881121a80487f0879d2ab0acc41
  Author: Brian Cain <bcain at quicinc.com>
  Date:   2022-01-27 (Thu, 27 Jan 2022)

  Changed paths:
    M libcxx/include/atomic

  Log Message:
  -----------
  Omit atomic_{,un}signed_lock_free if unsupported

On targets that have limited atomic support, e.g. ones that define
ATOMIC_*_LOCK_FREE to '1' ("sometimes lock free"), we would end up
referencing yet-undefined __libcpp_{,un}signed_lock_free.

This commit adds a guard to prevent these references for such
targets.

Differential Revision: https://reviews.llvm.org/D118391