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Summary

  1. [Automaton] Make Automaton thread-safe (details)
Commit 041f35c468088d315bae6c2a71ec901a12cca1b5 by James Molloy jmolloy
[Automaton] Make Automaton thread-safe
In an optimization to improve performance (rL375240) we added a
std::shared_ptr around the main table map. This is safe, but we also
ended up making the transcriber object a std::shared_ptr too. This has
mutable state, so must be copied when we copy the Automaton object. This
is very cheap; the main optimization was about the map `M` only.
Reported by Dan Palermo. No test as triggering this is rather hard from
a unit test.
The file was modifiedllvm/include/llvm/Support/Automaton.h