Noticed by Stef on 09/09/2020 as a curious code block that was failing
Forgot about it until now since we couldn't see exactly where it was
wrong
Code block was mixing x87 (Which forces a fallback to Interpreter) and
cmpxchg8b, which caused that code block to fail.
Since this op was broken with Unified Memory + Interpreter it wasn't
picked up by unit tests since those don't run in unified memory