Default VCS Python DUTs to no_save

[Martinnn674]

Summary

• default generated Python DUTs for VCS to pass -no_save when callers do not provide explicit simulator args
• preserve existing explicit-args behavior by only adding the default when args is empty
• add a render-level regression test for the VCS Python template and non-VCS output

Fixes #86.

Verification

• NO_BUILD_XSPCOMM=1 cmake . -Bbuild -DCMAKE_BUILD_TYPE=Release -DCMAKE_BUILD_PARALLEL=2
• NO_BUILD_XSPCOMM=1 cmake --build build --target test_codegen_python_vcs_defaults -j2
• ctest --test-dir build -R test_codegen_python_vcs_defaults --output-on-failure

[Sergeant-Salz]

@Martinnn674 In your patch, the flag is only used when args is None, however I think it might make sense to also append it to a non-empty tuple? Is there a reason you would avoid that?

I suggest:

def __init__(self, *args, **kwargs):
        {% if __SIMULATOR__ == "vcs" %}
        # For VCS we need this workaround. See issue #86
        if not args or '-no_save' not in args:
            args = args if args else () + ('-no_save',)
        {% endif %}

[Martinnn674]

Good point. I kept it empty only to avoid changing behavior for callers who already pass explicit VCS args, but I agree that if picker does not support VCS save/restore here, adding -no_save whenever it is absent is the better default.

Small note tho I think the suggested assignment would leave non empty args unchanged. I would update it to append while avoiding duplicates, something like:

if "-no_save" not in args:
    args = args + ("-no_save",)

That should preserve caller provided args and still make the workaround apply consistently.

[Makiras]

Because #88 successfully launched VCS by disabling ASLR without using the -no_save option, we have decided to abandon this workaround and instead opt for the disable ASLR approach which retains more functionality.

Of course, we still appreciate your efforts in submitting the PR.