[llvm] [NFC] add a pre-commit test case for patch 122741 (PR #135247)

[Tristan Ross via llvm-commits]

RossComputerGuy wrote:

I believe this is revealing a test failure:
```
llvm> /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -debug-only=isel    /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/test/CodeGen/PowerPC/undef-args.ll -o - 2>&1 | /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/FileCheck --check-prefix=CHECKISEL32 /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/test/CodeGen/PowerPC/undef-args.ll # RUN: at line 4
llvm> + /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/llc -verify-machineinstrs -mtriple powerpc-ibm-aix-xcoff -debug-only=isel /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/test/CodeGen/PowerPC/undef-args.ll -o -
llvm> + /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/FileCheck --check-prefix=CHECKISEL32 /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/test/CodeGen/PowerPC/undef-args.ll
llvm> /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/test/CodeGen/PowerPC/undef-args.ll:30:16: error: CHECKISEL32: expected string not found in input
llvm> ; CHECKISEL32: Initial selection DAG: %bb.0 'test32:entry'
llvm>                ^
llvm> <stdin>:1:1: note: scanning from here
llvm> llc: Unknown command line argument '-debug-only=isel'. Try: '/build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/llc --help'
llvm> ^
llvm> <stdin>:1:108: note: possible intended match here
llvm> llc: Unknown command line argument '-debug-only=isel'. Try: '/build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/llc --help'
llvm>                                                                                                            ^
llvm>
llvm> Input file: <stdin>
llvm> Check file: /build/llvm-src-21.0.0-unstable-2025-04-10/llvm/test/CodeGen/PowerPC/undef-args.ll
llvm>
llvm> -dump-input=help explains the following input dump.
llvm>
llvm> Input was:
llvm> <<<<<<
llvm>             1: llc: Unknown command line argument '-debug-only=isel'. Try: '/build/llvm-src-21.0.0-unstable-2025-04-10/llvm/build/bin/llc --help'
llvm> check:30'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
llvm> check:30'1                                                                                                                ?                        possible intended match
llvm>             2: llc: Did you mean '--debug-pass=isel'?
llvm> check:30'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
llvm> >>>>>>
llvm>
llvm> --
llvm>
llvm> ********************
llvm> ********************
llvm> Failed Tests (1):
llvm>   LLVM :: CodeGen/PowerPC/undef-args.ll
```

https://github.com/llvm/llvm-project/pull/135247