[llvm] [VPlan] Don't apply predication discount to non-originally-predicated blocks (PR #160449)

[Luke Lau via llvm-commits]

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@@ -760,28 +777,46 @@ define void @update_2_uses_in_same_recipe_in_merged_block(i32 %k) {
 ; CHECK-NEXT: vector.body:
 ; CHECK-NEXT:   EMIT vp<[[CAN_IV:%.+]]> = CANONICAL-INDUCTION
 ; CHECK-NEXT:   ir<%iv> = WIDEN-INDUCTION ir<0>, ir<1>, vp<[[VF]]>
+; CHECK-NEXT:   vp<[[STEPS:%.+]]> = SCALAR-STEPS vp<[[CAN_IV]]>, ir<1>, vp<[[VF]]>
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lukel97 wrote:

Also done in f072e3c5518b, needed to pass -force-widen-divrem-via-safe-divisor=0 so that the div is scalarized

https://github.com/llvm/llvm-project/pull/160449