tree 5cd1589662ef6d83652e1985f53d1cfc5109560e
parent 806aa645a2bcfbf7442c1bc15165f95959a3b3a3
author Johannes Doerfert <johannes@jdoerfert.de> 1684453571 -0700
committer Copybara-Service <copybara-worker@google.com> 1686010531 -0700

[Attributor] Identify and remove no-op fences

The logic and implementation follows the removal of no-op barriers. If
the fence is not making updates visible, either to the world or the
current thread, it is not needed. Said differently, the fences we remove
do not establish synchronization (happens-before) edges.
This allows us to eliminate some of the regression caused by:
  https://reviews.llvm.org/D145290

GitOrigin-RevId: cb17c48fdd8c0f8ab6cd7ad3f197b052db20d1f6