Florian Hahn 97687b7aea [VPlan] Add active-lane-mask as VPlan-to-VPlan transformation. ...

This patch updates the mask creation code to always create compares of
the form (ICMP_ULE, wide canonical IV, backedge-taken-count) up front
when tail folding and introduce active-lane-mask as later
transformation.

This effectively makes (ICMP_ULE, wide canonical IV, backedge-taken-count)
the canonical form for tail-folding early on. Introducing more specific
active-lane-mask recipes is treated as a VPlan-to-VPlan optimization.

This has the advantage of keeping the logic  (and complexity) of
introducing active-lane-mask recipes in a single place, instead of
spreading the logic out across multiple functions. It also simplifies
initial VPlan construction and enables treating introducing EVL as
similar optimization.

Reviewed By: Ayal

Differential Revision: https://reviews.llvm.org/D158779

2023-09-25 13:34:45 +01:00

43 KiB

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