[llvm] [LV] Re-org tests; introduce iv-select-cmp-decreasing.ll (PR #141769)

[Mel Chen via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 5
+; RUN: opt -passes=loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -S < %s | FileCheck %s
+; RUN: opt -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=4 -S < %s | FileCheck %s
+; RUN: opt -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=1 -S < %s | FileCheck %s
+
+define i64 @not_vectorized_select_decreasing_induction_icmp_const_start(ptr %a) {
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Mel-Chen wrote:

Maybe we don’t need the `not_vectorized` prefix here, as this function can actually be vectorized.

https://github.com/llvm/llvm-project/pull/141769