Change how JAX Keras backend requirement is reported (#2420)

Signed-off-by: Andrzej Kotłowski <andrzej.kotlowski@intel.com>

Author: anko-intel

docs/source/JAX.md

@@ -10,7 +10,8 @@ JAX
 
 ## Introduction
 
-`neural_compressor_jax` provides an API for applying quantization on Keras models such as ViT and Gemma3.
+`neural_compressor.jax` provides an API for applying quantization to Keras models such as ViT and Gemma3.
+Since only JAX is supported as the Keras backend, the environment variable `KERAS_BACKEND` should be set to `jax`.
 The following 8-bit floating-point formats are supported: `fp8_e4m3` and `fp8_e5m2`.
 
 Quantized models can be saved and loaded using standard Keras APIs

neural_compressor/jax/quantization/layers_dynamic.py

@@ -37,12 +37,6 @@
     verify_api,
 )
 
-if keras.config.backend() != "jax":
-    raise ValueError(
-        f"{__name__} only supports JAX backend, but the current backend is {keras.config.backend()}.\n"
-        'Consider setting KERAS_BACKEND env var to "jax".'
-    )
-
 dynamic_quant_mapping = {}
 
 

neural_compressor/jax/quantization/layers_static.py

@@ -37,12 +37,6 @@
     verify_api,
 )
 
-if keras.config.backend() != "jax":
-    raise ValueError(
-        f"{__name__} only supports JAX backend, but the current backend is {keras.config.backend()}.\n"
-        'Consider setting KERAS_BACKEND env var to "jax".'
-    )
-
 static_quant_mapping = {}
 
 

neural_compressor/jax/quantization/quantize.py

@@ -21,7 +21,7 @@
 from neural_compressor.common import logger
 from neural_compressor.common.base_config import BaseConfig, ComposableConfig, config_registry
 from neural_compressor.common.utils import Mode, log_process
-from neural_compressor.jax.utils import algos_mapping
+from neural_compressor.jax.utils import algos_mapping, check_backend
 
 
 def need_apply(configs_mapping: Dict[Tuple[str, callable], BaseConfig], algo_name):
@@ -58,6 +58,7 @@ def quantize_model(
         keras.Model: The quantized model.
     """
 # fmt: on
+    check_backend()
     if not inplace:
         raise NotImplementedError("Out of place quantization is not supported yet. "
                                   "Please set parameter inplace=True for quantize_model() to modify the model in-place")

neural_compressor/jax/quantization/saving.py

@@ -28,7 +28,7 @@
 from neural_compressor.common import logger
 from neural_compressor.common.base_config import config_registry
 from neural_compressor.jax.quantization.config import FRAMEWORK_NAME, BaseConfig, DynamicQuantConfig, StaticQuantConfig
-from neural_compressor.jax.utils.utility import dtype_mapping, iterate_over_layers
+from neural_compressor.jax.utils.utility import check_backend, dtype_mapping, iterate_over_layers
 
 
 def quant_config_to_json_object(quant_config: BaseConfig) -> dict:
@@ -446,6 +446,7 @@ def prepare_deserialized_quantized_model(
     Returns:
         Union[KerasQuantizedModelWrapperMixin, KerasQuantizedModelBackboneWrapper]: The transformed quantized model/backbone wrapper.
     """
+    check_backend()
     model_info = quant_config.get_model_info(model)
     configs_mapping = quant_config.to_config_mapping(model_info=model_info)
 

neural_compressor/jax/utils/__init__.py

@@ -14,4 +14,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from neural_compressor.jax.utils.utility import algos_mapping, register_algo
+from neural_compressor.jax.utils.utility import algos_mapping, register_algo, check_backend

neural_compressor/jax/utils/utility.py

@@ -30,6 +30,23 @@
 from neural_compressor.common import logger
 
 
+def check_backend(raise_error=True):
+    """Check if the current Keras backend is JAX and log a warning or error if not."""
+
+    if keras.config.backend() != "jax":
+        message = (
+            f"neural_compressor.jax only supports JAX backend, but the current Keras backend is {keras.config.backend()}. "
+            'Consider setting KERAS_BACKEND env var to "jax".'
+        )
+        if raise_error:
+            raise ValueError(message)
+        else:
+            logger.warning(message)
+
+
+check_backend(raise_error=False)
+
+
 def add_fp8_support(function):
     """Extend a dtype size function to support FP8 dtypes.