[PATCH] D27855: [InstCombine] try to extend nonnull-ness of arguments from a callsite back to its parent function

Sanjay Patel via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Dec 16 10:00:41 PST 2016

spatel created this revision.
spatel added reviewers: hfinkel, mkuper, majnemer.
spatel added a subscriber: llvm-commits.
Herald added a subscriber: mcrosier.

As discussed here:
...we should be able to propagate 'nonnull' info from a callsite back to its parent.

The original motivation for this patch is our botched optimization of "dyn_cast" (PR28430), but this won't solve that problem alone.

I think this is the strongest nonnull transform of this type because tagging the argument can enable transforms for all other instructions in the function. Possible follow-ups would handle cases where we can use nonnull to directly eliminate an icmp (InstSimplify+ValueTracking), or add llvm.assume to trigger existing transforms.



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