[libcxx-commits] [PATCH] D123175: [libcxx] Add flag to disable __builtin_assume in _LIBCPP_ASSERT

[Arthur Eubanks via Phabricator via libcxx-commits]

aeubanks added a comment.

I was talking to some people about this and due to the way assumes are handled in the IR, it's not an automatic win to sprinkle assumes everywhere. There is inherently a tradeoff when you add assumes (assumes are instructions and are control flow dependent, adding assumes can prevent some optimizations) so they should be added carefully. Was there a concrete speedup seen when you initially landed this? But either way I think there needs to be a way to opt out of this behavior.


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  https://reviews.llvm.org/D123175/new/

https://reviews.llvm.org/D123175