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

[Florian Hahn via llvm-commits]

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@@ -1,7 +1,7 @@
 ; RUN: opt -S -passes=loop-vectorize -mtriple=s390x-linux-gnu -vectorizer-min-trip-count=8 < %s | FileCheck %s
 
 define i32 @main(i32 %arg, ptr nocapture readnone %arg1) #0 {
-;CHECK: vector.body:
+; CHECK-NOT: vector.body:
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fhahn wrote:

Yep, generated full check lines for the file in 959ff45bdad1777598c89b662fc98653a19eb8a3; there are no vector instructions generated, because the induction is scalarizied, which isn't modeled in the legacy cost model (a similar case is in `llvm/test/Transforms/LoopVectorize/X86/induction-costs.ll`)

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