[llvm] [LoopVectorize] Don't discount instructions scalarized due to tail folding (PR #109289)

[John Brawn via llvm-commits]

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@@ -21,7 +21,31 @@ define void @foo(ptr noalias %a, ptr noalias %b, ptr noalias %c, i64 %N) {
 ; CHECK-NEXT:   vector.body:
 ; CHECK-NEXT:     EMIT vp<[[CAN_IV:%.+]]> = CANONICAL-INDUCTION ir<0>, vp<[[CAN_INC:%.*]]>
 ; CHECK-NEXT:     WIDEN-INDUCTION %iv = phi 0, %iv.next, ir<1>, vp<[[VF]]>
+; CHECK-NEXT:     vp<[[STEPS:%.+]]> = SCALAR-STEPS vp<[[CAN_IV]]>, ir<1>
 ; CHECK-NEXT:     EMIT vp<[[CMP:%.+]]> = icmp ule ir<%iv>, vp<[[BTC]]>
+; CHECK-NEXT:   Successor(s): pred.load
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john-brawn-arm wrote:

Perhaps the best thing to do here is to change the test to check that it's making the correct decision, which is not to vectorize.

https://github.com/llvm/llvm-project/pull/109289