[llvm] [LV] Add support for cmp reductions with decreasing IVs. (PR #140451)

[Ramkumar Ramachandra via llvm-commits]

================
@@ -1760,55 +1760,178 @@ define i64 @not_vectorized_select_decreasing_induction_icmp_const_start(ptr %a)
 ; CHECK-VF4IC1-LABEL: define i64 @not_vectorized_select_decreasing_induction_icmp_const_start(
----------------
artagnon wrote:

Tweak function name s/not_vectorized_//?

https://github.com/llvm/llvm-project/pull/140451