[all-commits] [llvm/llvm-project] d83ca6: [OpenMP] Fix data-race in new device RTL

[Joseph Huber via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: d83ca624a1d52b600ddbd8bfcbb3d5d7c6003af7
      https://github.com/llvm/llvm-project/commit/d83ca624a1d52b600ddbd8bfcbb3d5d7c6003af7
  Author: Joseph Huber <jhuber6 at vols.utk.edu>
  Date:   2021-09-23 (Thu, 23 Sep 2021)

  Changed paths:
    M openmp/libomptarget/DeviceRTL/src/Parallelism.cpp

  Log Message:
  -----------
  [OpenMP] Fix data-race in new device RTL

This patch fixes a data-race observed when using the new device runtime
library. The Internal control variable for the parallel level is read in
the `__kmpc_parallel_51` function while it could potentially be written
by other threads. This causes data corruption and will cause
nondetermistic behaviour in the runtime. This patch fixes this by adding
an explicit synchronization before the region starts.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D110366