[PATCH] D93850: [InstCombine] Rewrite (switch (zext X)) as (switch X).

[Chenguang Wang via Phabricator via llvm-commits]

wecing added a comment.

@lebedev.ri , which "hook" did you mean?

I think the existing fold is too aggressive. Please take a look at the example I gave in an earlier comment -- doing a less strict fold first gives GVN a chance to optimize the IR.
When the new fold is triggered, the existing more aggressive fold would be triggered (if `NewWidth` happens to be a standard integer type, e.g. `i8`, so that `shouldChangeType()` returns true) the next time InstCombine gets executed.


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  https://reviews.llvm.org/D93850/new/

https://reviews.llvm.org/D93850