[PATCH] D37017: [DAGCombiner] fold assertzexts separated by trunc
Alexander Ivchenko via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 22 14:52:27 PDT 2017
aivchenk added a comment.
That's certainly a much better approach than the original. Couple of comments/questions:
- We eliminate the "outer" assert by making "inner" stronger. In a sense, this essentially moves the information about the extension further away from the use. Is there some sort of canonicalization or a convention for that? The other way of removing redundancy would be just to eliminate the weaker "inner" assert, though it would not solve the initial problem for handling AssertZext in the backend. But may be the problem is that we don't handle AssertZext properly?
- Should we implement the same idea for AssertSext?
https://reviews.llvm.org/D37017
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