def test_read_nonexistent_returns_none(self):
        db = perfRunner.read_tuning_db("/nonexistent/path.tsv")
        assert db is None


class TestParseDataTypes:
    """Tests for parse_data_types (gemm data types)."""

    def test_empty_returns_defaults(self):
        dtypes, out_map = perfRunner.parse_data_types(None)

def infer_codegen_flags_from_arch(arch: str,
                                  requested_codepath: str = 'none') -> tuple[str, list[str]]:
    """Infers codepath and optional rocmlir-gen flags from architecture.

    The inferred codepath is used to pick the perf_config family. By default we
    rely on rocmlir-gen arch auto-detection and return no explicit feature
    flags; flags are only emitted when a codepath override is explicitly
    requested.

    Returns ('unknown', []) when inference fails.
    """
    supported_codepath = ['mfma', 'vanilla', 'wmma']
    codepath = requested_codepath

    if codepath not in supported_codepath:
        features = lookup_arch_info(arch).default_features
        if has_feature(features, GemmFeatures.MFMA):
            codepath = 'mfma'
        elif has_feature(features, GemmFeatures.WMMA):
            codepath = 'wmma'
        else:
            codepath = 'vanilla'

    if requested_codepath in supported_codepath:
        return (codepath, get_codegen_flags_for_codepath(arch, codepath))
    return (codepath, [])

def get_num_cu(device_id: int = 0):
    # In native mode, min_num_cu contains the actual number of CUs instead of the minimum
    return lookup_arch_info(f"native:{device_id}").min_num_cu

def assign_num_cu():
    if args.c:
        return int(args.c)
    print(
        "Using info from GPU 0 in your system, the data should have be obtained from the same GPU.")
    return lookup_arch_info("native:0").min_num_cu