[llvm] [VPlan] Don't use the legacy cost model for loop conditions (PR #156864)

[David Sherwood via llvm-commits]

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@@ -9,11 +9,12 @@ define i64 @test(ptr %a, ptr %b) #0 {
 ; CHECK-LABEL: LV: Checking a loop in 'test'
 ; CHECK: Cost of 1 for VF 8: induction instruction   %i.iv.next = add nuw nsw i64 %i.iv, 1
 ; CHECK-NEXT: Cost of 0 for VF 8: induction instruction   %i.iv = phi i64 [ 0, %entry ], [ %i.iv.next, %for.body ]
-; CHECK-NEXT: Cost of 1 for VF 8: exit condition instruction   %exitcond.not = icmp eq i64 %i.iv.next, 16
 ; CHECK-NEXT: Cost of 0 for VF 8: EMIT vp<{{.+}}> = CANONICAL-INDUCTION ir<0>, vp<%index.next>
+; CHECK: Cost of 1 for VF 8: EMIT branch-on-count vp<%index.next>, vp<{{.+}}>
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david-arm wrote:

I think @igogo-x86 added this file in #106699. You might also want to remove `addFullyUnrolledInstructionsToIgnore`, since you're now dealing with the cost properly in vplan?

https://github.com/llvm/llvm-project/pull/156864