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[ARM] PREDICATE_CAST demanded bits
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Authored by dmgreen on Nov 27 2020, 1:08 AM.

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Summary

The PREDICATE_CAST node is used to model moves between MVE predicate registers and gpr's, and eventually become a VMSR p0, rn. When moving to a predicate only the bottom 16 bits of the sources register are demanded. This adds a simple fold for that, allowing it to potentially remove instructions like uxth.

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dmgreen created this revision.Nov 27 2020, 1:08 AM
dmgreen requested review of this revision.Nov 27 2020, 1:08 AM
simon_tatham accepted this revision.Nov 27 2020, 1:33 AM
This revision is now accepted and ready to land.Nov 27 2020, 1:33 AM
This revision was automatically updated to reflect the committed changes.