[llvm] [VPlan] Use pointer to member 0 as VPInterleaveRecipe's pointer arg. (PR #106431)

[via llvm-commits]

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@@ -2413,10 +2414,11 @@ void VPInterleaveRecipe::execute(VPTransformState &State) {
     Idx = State.Builder.CreateSub(RuntimeVF, State.Builder.getInt32(1));
     Idx = State.Builder.CreateMul(Idx,
                                   State.Builder.getInt32(Group->getFactor()));
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ayalz wrote:

Does the above comment of adjusting the index from the first vector lane (lane zero?) rather than using the pointer of the last lane, still hold? If so, this adjusting is invariant and better be placed in the preheader, possibly later by licm?

https://github.com/llvm/llvm-project/pull/106431