[clang-tools-extra] [llvm] [clang] [AArch64] Add an AArch64 pass for loop idiom transformations (PR #72273)

[via cfe-commits]

dyung wrote:

Hi @david-arm, the test you added, byte-compare-index.ll seems to be failing on several bots, can you take a look?

For example on https://lab.llvm.org/buildbot/#/builders/139/builds/56740:
```
******************** TEST 'LLVM :: Transforms/LoopIdiom/AArch64/byte-compare-index.ll' FAILED ********************
Exit Code: 2
Command Output (stderr):
--
RUN: at line 2: /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/opt -aarch64-lit -disable-aarch64-lit-all=false -aarch64-lit-verify -verify-dom-info -mtriple aarch64-unknown-linux-gnu -mattr=+sve -S < /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll | /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll
+ /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll
+ /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/opt -aarch64-lit -disable-aarch64-lit-all=false -aarch64-lit-verify -verify-dom-info -mtriple aarch64-unknown-linux-gnu -mattr=+sve -S
opt: Unknown command line argument '-aarch64-lit'.  Try: '/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/opt --help'
opt: Did you mean '--march'?
opt: Unknown command line argument '-disable-aarch64-lit-all=false'.  Try: '/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/opt --help'
opt: Did you mean '--disable-sched-stalls=false'?
opt: Unknown command line argument '-aarch64-lit-verify'.  Try: '/home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/opt --help'
opt: Did you mean '--tail-dup-verify'?
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/build/bin/FileCheck /home/buildbot/buildbot-root/llvm-clang-x86_64-sie-ubuntu-fast/llvm-project/llvm/test/Transforms/LoopIdiom/AArch64/byte-compare-index.ll
--
```

https://github.com/llvm/llvm-project/pull/72273