[PATCH] D65186: [MustExec] Add a generic "must-be-executed-context" explorer

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

I'm not sure I understand the design/purpose of this utility. As far as I can see, the main benefit this has over a standard guaranteed-to-transfer loop is that it will be able to continue into a unique successor BB. As most must-exec uses I've seen (including your ArgPromotion example, as well as attribute deduction uses) are interested in instructions that must-exec from entry, this will not happen for non-degenerate CFGs (where BBs have not been merged).

To get something more accurate than a guaranteed-to-transfer loop over the entry block for purposes like attribute deduction, a different interface would be needed that can handle multiple successor blocks. Basically a backwards propagation that discards facts if there's no guaranteed-transfer.


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https://reviews.llvm.org/D65186