[PATCH] D36395: [InstCombine] narrow rotate left/right patterns to eliminate zext/trunc (PR34046)

Sanjay Patel via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Aug 7 14:27:02 PDT 2017

spatel updated this revision to Diff 110088.
spatel added a comment.

Patch updated:

1. Add an assert for the shouldChangeType() guard that's in the caller function.
2. Replace the explicit match for zext of the shift value with a call to MaskedValueIsZero().
3. Remove the MaskedValueIsZero() check for the shift amount and generate our own masks to make the transform safe:


4. Add test to exercise #2 and #3.



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