[llvm] [LV] Reduce register usage for scaled reductions (PR #133090)

[Sam Tebbs via llvm-commits]

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@@ -45,9 +45,9 @@ define void @load_and_compare_only_used_by_assume(ptr %a, ptr noalias %b) {
 ; CHECK-LABEL: LV: Checking a loop in 'load_and_compare_only_used_by_assume'
 ; CHECK: LV(REG): VF = vscale x 4
 ; CHECK-NEXT: LV(REG): Found max usage: 2 item
-; CHECK-NEXT: LV(REG): RegisterClass: Generic::ScalarRC, 2 registers
-; CHECK-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 1 registers
-; CHECK-NEXT: LV(REG): Found invariant usage: 0 item
+; CHECK-NEXT: LV(REG): RegisterClass: Generic::ScalarRC, 3 registers
+; CHECK-NEXT: LV(REG): RegisterClass: Generic::VectorRC, 2 registers
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SamTebbs33 wrote:

Rebasing on top of Florian's merged PR has fixed this and the exit-branch-cost.ll diff, thanks for having a look.

https://github.com/llvm/llvm-project/pull/133090