[llvm] [VPlan] Support scalable VFs in narrowInterleaveGroups. (PR #154842)

[Philip Reames via llvm-commits]

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@@ -3574,7 +3574,7 @@ void VPlanTransforms::narrowInterleaveGroups(VPlan &Plan, ElementCount VF,
       continue;
 
     // Bail out on non-consecutive interleave groups.
-    if (!isConsecutiveInterleaveGroup(InterleaveR, FixedVF, TypeInfo,
+    if (!isConsecutiveInterleaveGroup(InterleaveR, VFMinVal, TypeInfo,
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preames wrote:

Stylistically, this is a bit confusing.  Maybe instead pass in the ElementCount, and adjust the routine to work in terms of TypeSize and perform the final check in terms of not being equal to VF, but a multiple of?

Though, I think I'm a bit confused on what this check is actually doing.  This seems to be disallowing fixed VFs which are a multiple of the interleave group size?  Is that an intentional restriction?

https://github.com/llvm/llvm-project/pull/154842