Adds the ability to build static archives in addition to shared objects

[Micky774]

Motivation

TE currently relies on libmha_{b, f}wd.so to provide AITER symbols at runtime, however if other projects (e.g. pytorch) also build the AITER library, but of a different version, then loading the same symbols can create conflict. To avoid this, we at TE would like to be able to generate static archives as part of the build triggered through aiter/op_tests/cpp/mha/compile.py.

Technical Details

Gated by a new environment variable AITER_BUILD_STATIC, there is now a new rule inserted which will build libmha_*wd.a using AITER_AR_BIN (set to ar by default). Backwards compatibility is ensured by AITER_BUILD_STATIC being defaulted to 0.

Test Plan

Run aiter/op_tests/cpp/mha/compile.py and validate that the expected artifacts are produced.

Test Result

Submission Checklist

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

[Copilot]

Pull request overview

Adds an opt-in build path to produce static archives for the MHA forward/backward test libraries to avoid runtime symbol conflicts when multiple AITER versions are present.

Changes:

• Adds an ar tool variable to the generated Ninja config (overridable via AITER_AR_BIN).
• When AITER_BUILD_STATIC=1 and the output is libmha_fwd.so / libmha_bwd.so, emits a corresponding libmha_*wd.a archive build rule and includes it in Ninja defaults.

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[Copilot]

archive_rule is defined unconditionally here but then always either overwritten with the same contents in the emit_static_archive branch or replaced with [] in the else branch, so this initial definition is dead code. Consider defining archive_rule only inside the emit_static_archive branch (and otherwise leaving it empty) to avoid duplication and reduce confusion.

Suggested change

	archive_rule = ["rule archive"]
	archive_rule.append(
	" command = rm -f $out && $ar rcs $out @$out.rsp\n rspfile = $out.rsp\n rspfile_content = $in"
	)

[wangye805]

Can we detect whether it's .a or .so based on the library target ext?

[wangye805]

Probably we can add some argument/option and pass the library_target down from compile.py in op_tests/cpp/mha as libmha_fwd/bwd.a instead of libmha_fwd/bwd.so?