Discard check_LLVM_MAIN_REVISION object file

[kTorp]

Motivation

When running diffusion workloads on MI300/MI355 an unknown object file .-o kept being created in the current working directory. It was traced back to a function check_LLVM_MAIN_REVISION() which was introduced in #1703 and is hit during JIT compilation of aiter kernels.

This PR introduces a minimal fix to prevent this stray .-o object file from being created during aiter JIT compilation without affecting the LLVM revision check logic.

Technical Details

The check_LLVM_MAIN_REVISION() function in aiter/jit/core.py compiles a small test snippet using hipcc via stdin.

echo '#include <tuple> 
__host__ __device__ void func(){std::tuple<int, int> t = std::tuple(1, 1);}' | hipcc -x hip -P -c -Wno-unused-command-line-argument -

When hipcc is invoked with -c (compile-only) it derives the output object filename from the input filename. Because the input here is stdin (denoted by the trailing -), the compiler treats the filename as - and writes -.o into the current directory. That file is a side-effect and never referenced/consumed; the function only cares about the exit code.

The fix is minimal (discarding the object file using -o /dev/null as is done in hip_flag_checker in the same file).

Test Plan

1. Tested diffusion workloads with aiter compiled kernels with and without the fix.
2. Testing the function return code

Test Result

1. Generated images kept the same quality and e2e performance speed before and after
2. Function returned the same code before and after

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[github-actions]

🏷️ CI Guide

Runs automatically on every PR:

• ✅ Pre-checks (submodule verification, code formatting)
• ✅ Aiter op tests (gfx942 + gfx950)
• ✅ Triton tests (only when aiter/ops/triton/** or related paths are changed)

Extended tests (opt-in via labels):

Label	Tests
ci:sglang	SGLang integration tests
ci:atom	ATOM benchmark (DeepSeek-R1 + GPT-OSS)
ci:vllm	vLLM benchmark
ci:all	All of the above

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