[llvm] [WIP][LoopIdiomVectorize] Recognize and transform minidx pattern (PR #144987)

[David Sherwood via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=loop-vectorize -force-vector-width=1 -force-vector-interleave=4 -S %s | FileCheck %s --check-prefix=CHECK-REV-MIN-VW1-IL4
+; RUN: opt -passes=loop-vectorize -force-vector-width=4 -force-vector-interleave=1 -S %s | FileCheck %s --check-prefix=CHECK-REV-MIN-VW4-IL1
+; RUN: opt -passes=loop-vectorize -force-vector-width=4 -force-vector-interleave=2 -S %s | FileCheck %s --check-prefix=CHECK-REV-MIN-VW4-IL2
+; RUN: opt -passes=loop-idiom-vectorize -S -mtriple=aarch64 -mattr=+sve %s | FileCheck %s --check-prefix=CHECK-LOOP-IDIOM
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david-arm wrote:

In general, loop idiom vectorize tests live in a different directory. See `test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll` as an example.

https://github.com/llvm/llvm-project/pull/144987