[llvm] [LV] Move check if any vector insts will be generated to VPlan. (PR #96622)

[Florian Hahn via llvm-commits]

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@@ -1,4 +1,4 @@
-; RUN: opt < %s -passes=loop-vectorize -S | FileCheck %s
+; RUN: opt < %s -passes=loop-vectorize -force-vector-width=4 -S | FileCheck %s
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fhahn wrote:

This won't generate any vector instructions due to dead instructions. I think in this case it makes sense to retain the vectorization behavior by forcing the VF, as from the comment the goal is to guard against creating invalid phis outside the vector loop.

https://github.com/llvm/llvm-project/pull/96622