Add command-line options in Windows' llm-ptq example for Gather nodes' INT4 ONNX quantization (#418)

Signed-off-by: vipandya <vipandya@nvidia.com>

examples/windows/onnx_ptq/genai_llm/README.md

@@ -58,6 +58,8 @@ The table below lists key command-line arguments of the ONNX PTQ example script.
 | `--no_position_ids` | Default: position_ids input enabled | Use this option to disable position_ids input in calibration data|
 | `--enable_mixed_quant` | Default: disabled mixed quant | Use this option to enable mixed precsion quantization|
 | `--layers_8bit` | Default: None | Use this option to Overrides default mixed quant strategy|
+| `--gather_quantize_axis` | Default: None | Use this option to enable INT4 quantization of Gather nodes - choose 0 or 1|
+| `--gather_block_size` | Default: 32 | Block-size for Gather node's INT4 quantization (when its enabled using gather_quantize_axis option)|
 
 Run the following command to view all available parameters in the script:
 

examples/windows/onnx_ptq/genai_llm/quantize.py

@@ -441,6 +441,8 @@ def main(args):
         awqclip_bsz_col=args.awqclip_bsz_col,
         enable_mixed_quant=args.enable_mixed_quant,
         layers_8bit=args.layers_8bit,
+        gather_block_size=args.gather_block_size,
+        gather_quantize_axis=args.gather_quantize_axis,
     )
     logging.info(f"\nQuantization process took {time.time() - t} seconds")
 
@@ -553,7 +555,19 @@ if __name__ == "__main__":
         "--block_size",
         type=int,
         default=128,
-        help="Block size for AWQ quantization",
+        help="Block size for INT4 quantization of MatMul/Gemm nodes",
+    )
+    parser.add_argument(
+        "--gather_block_size",
+        type=int,
+        default=32,
+        help="Block size for INT4 quantization of Gather nodes",
+    )
+    parser.add_argument(
+        "--gather_quantize_axis",
+        type=int,
+        default=None,
+        help="Quantization axis for INT4 quantization of Gather nodes",
     )
     parser.add_argument(
         "--use_zero_point",