[PATCH] D32720: [LICM] Introduce a finer granularity option to compute early exits.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

Thinking about it a bit more, instead of storing a list of instructions which can exit the loop early, you could store a list of basic blocks which are guaranteed to execute, and a mapping from those basic blocks to the first instruction in each basic block which could exit early.  That would allow "constant-time" lookups, at the expense of a bit more computation upfront.

I agree it doesn't make sense to try to recompute if an early exit is erased; that should be very rare.  (Granted, it might be a little bit more common than it should be: it looks like isGuaranteedToTransferExecutionToSuccessor is missing a few important cases which isInstructionTriviallyDead catches.)


https://reviews.llvm.org/D32720