Florian Hahn 6f253e87dd
Reapply "[VPlan] Run narrowInterleaveGroups during general VPlan optimizations. (#149706)"
This reverts commit 8d29d09309654541fb2861524276ada6a3ebf84c.

The underlying issue causing the revert has been fixed independently
as 301fa24671256734df6b7ee65f23ad885400108e.

Original message:
Move narrowInterleaveGroups to to general VPlan optimization stage.

To do so, narrowInterleaveGroups now has to find a suitable VF where all
interleave groups are consecutive and saturate the full vector width.

If such a VF is found, the original VPlan is split into 2:
 a) a new clone which contains all VFs of Plan, except VFToOptimize, and
 b) the original Plan with VFToOptimize as single VF.

The original Plan is then optimized. If a new copy for the other VFs has
been created, it is returned and the caller has to add it to the list of
candidate plans.

Together with https://github.com/llvm/llvm-project/pull/149702, this
allows to take the narrowed interleave groups into account when
computing costs to choose the best VF and interleave count.

One example where we currently miss interleaving/unrolling when
narrowing interleave groups is https://godbolt.org/z/Yz77zbacz

PR: https://github.com/llvm/llvm-project/pull/149706
2026-02-15 20:10:10 +00:00
..