Support MXINT4 scheme

auto_round/__main__.py

@@ -756,7 +756,11 @@ def tune(args):
                     suffix = f"a{autoround.act_bits}"
             else:
                 suffix = f"g{autoround.group_size}"
-        prefix = autoround.data_type.lower().replace("_", "") if "int" not in autoround.data_type else ""
+        prefix = (
+            autoround.data_type.lower().replace("_", "")
+            if "int" not in autoround.data_type or "mx" in autoround.data_type
+            else ""
+        )
         export_dir = os.path.join(
             args.output_dir,
             model_name.split("/")[-1] + (f"-{prefix}" if prefix else "") + f"-w{autoround.bits}{suffix}",

auto_round/compressors/utils.py

@@ -35,6 +35,7 @@ class BackendDataType(str, Enum):
     STANDARD_FP = "fp"
     MX_FP = "mx_fp"
     NV_FP = "nv_fp"
+    MX_INT = "mx_int"
 
 
 def is_standard_fp(backend):
@@ -47,6 +48,11 @@ def is_mx_fp(backend):
     return BackendDataType.MX_FP in backend
 
 
+def is_mx_int(backend):
+    backend = backend.lower()
+    return BackendDataType.MX_INT in backend
+
+
 def is_nv_fp(backend):
     backend = backend.lower()
     return BackendDataType.NV_FP in backend

auto_round/experimental/qmodules/__init__.py

@@ -12,6 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from auto_round.experimental.qmodules.mx import MXFP4QuantLinear, MXFP8QuantLinear, HadamardMXFP4QuantLinear
+from auto_round.experimental.qmodules.mx import (
+    MXFP4QuantLinear,
+    MXFP8QuantLinear,
+    MXINT4QuantLinear,
+    HadamardMXFP4QuantLinear,
+)
 from auto_round.experimental.qmodules.nvfp4 import NVFP4QuantLinear
 from auto_round.experimental.qmodules.fp8_static import WeightFP8ActFP8StaticQuantLinear

auto_round/experimental/qmodules/mx.py

@@ -20,10 +20,11 @@
 from auto_round.data_type.utils import get_quant_func
 from auto_round.experimental.qmodules.base import QModuleBase
 from auto_round.experimental.qmodules.fp4_utils import unpack_fp4_from_uint8
+from auto_round.experimental.qmodules.mxint4_utils import unpack_int4_from_uint8
 from auto_round.logger import logger
 from auto_round.schemes import QuantizationScheme
 
-__all__ = ["MXFP4QuantLinear", "MXFP8QuantLinear"]
+__all__ = ["MXFP4QuantLinear", "MXFP8QuantLinear", "MXINT4QuantLinear"]
 
 SUPPORTED_HIGHER_DTYPE = [torch.bfloat16, torch.float16, torch.float32]
 E8M0_EXPONENT_BIAS = 127
@@ -196,6 +197,47 @@ def unpack_data(self, packed_data: torch.Tensor) -> torch.Tensor:
         return unpacked_data
 
 
+class MXINT4QuantLinear(MXQuantLinearBase):
+    """
+    Quantized linear layer using the MXINT4 quantization scheme.
+    """
+
+    def __init__(self, *args, **kwargs):
+        self.weight_name = "weight_packed"
+        super().__init__(*args, **kwargs)
+
+    def initialize_weights(self, weight: Optional[torch.Tensor]) -> torch.Tensor:
+        weight_dtype = torch.uint8
+        weight_in_features = self.in_features // 2
+        return torch.zeros((self.out_features, weight_in_features), dtype=weight_dtype) if weight is None else weight
+
+    def dequant_weight_online(self) -> torch.Tensor:
+        if self.pre_dequantized:
+            return self.weight
+        dq_weight = self.dequant_mx_tensor(self.weight_packed, self.weight_scale)
+        return dq_weight
+
+    def unpack_data(self, packed_data: torch.Tensor) -> torch.Tensor:
+        m, half_n = packed_data.shape
+        unpacked_data = unpack_int4_from_uint8(packed_data, m, half_n * 2, dtype=self.dtype)
+        return unpacked_data
+
+    @classmethod
+    def from_original(cls, config: Optional[QuantizationScheme], original_layer: torch.nn.Linear):
+        """
+        Create an `MXQuantLinear` layer from an original linear layer.
+        """
+        logger.warning_once("MXINT quantization is still in experimental stage, the inference speed might be slow.")
+        qdq_linear = cls(
+            in_features=original_layer.in_features,
+            out_features=original_layer.out_features,
+            config=config,
+            bias=original_layer.bias,
+            dtype=original_layer.weight.dtype,
+        )
+        return qdq_linear
+
+
 class HadamardMXFP4QuantLinear(MXFP4QuantLinear):
     """
     Quantized linear layer using the MXFP4 quantization scheme.

auto_round/experimental/qmodules/mxint4_utils.py

@@ -0,0 +1,108 @@
+# Copyright (c) 2026 Intel Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# Copyright (c) 2021 - present / Neuralmagic, Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Optional
+
+import torch
+
+_DEVICE_E0M4_TENSORS = {}
+
+# Constants for INT4 values
+_E0M4_VALUES = [0.0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75]
+
+
+def get_e0m4_tensor(device):
+    """Get device-specific E0M4 lookup tensor, creating it if needed."""
+    device_str = str(device)
+    if device_str not in _DEVICE_E0M4_TENSORS:
+        _DEVICE_E0M4_TENSORS[device_str] = torch.tensor(_E0M4_VALUES, dtype=torch.float32, device=device)
+    return _DEVICE_E0M4_TENSORS[device_str]
+
+
+def unpack_int4_from_uint8(
+    a: torch.Tensor, m: int, n: int, dtype: Optional[torch.dtype] = torch.bfloat16
+) -> torch.Tensor:
+    """
+    Unpacks uint8 values into int4. Each uint8 contains two int4 values
+    (low nibble first). The 4-bit indices are mapped to int4 values using kE0M4ToFloat.
+    """
+    if a.device.type == "cuda":
+        return _unpack_int4_from_uint8_cuda(a, m, n, dtype)
+    else:
+        return _unpack_int4_from_uint8_cpu(a, m, n, dtype)
+
+
+@torch.compiler.disable()
+def _unpack_int4_from_uint8_cpu(
+    a: torch.Tensor, m: int, n: int, dtype: Optional[torch.dtype] = torch.bfloat16
+) -> torch.Tensor:
+    return _unpack_int4_from_uint8(a, m, n, dtype)
+
+
+# @torch.compile(fullgraph=True, dynamic=True)
+def _unpack_int4_from_uint8_cuda(
+    a: torch.Tensor, m: int, n: int, dtype: Optional[torch.dtype] = torch.bfloat16
+) -> torch.Tensor:
+    return _unpack_int4_from_uint8(a, m, n, dtype)
+
+
+def _unpack_int4_from_uint8(
+    a: torch.Tensor, m: int, n: int, dtype: Optional[torch.dtype] = torch.bfloat16
+) -> torch.Tensor:
+    """
+    Unpacks uint8 values into int4. Each uint8 consists of two int4 values
+    (i.e. first four bits correspond to one int4 value, last four correspond to a
+    consecutive int4 value). The bits represent an index, which are mapped to an int4
+    value.
+
+    :param a: tensor to unpack
+    :param m: original dim 0 size of the unpacked tensor
+    :param n: original dim 1 size of the unpacked tensor
+    :param dtype: dense dtype to cast the unpacked tensor to
+    """
+    assert a.dtype == torch.uint8, f"expected uint8, got {a.dtype}"
+
+    # Vectorized nibble processing
+    a_flat = a.flatten()
+    high = (a_flat & 0xF0) >> 4  # Upper nibbles
+    low = a_flat & 0x0F  # Lower nibbles
+
+    # Combine nibbles for batch processing
+    combined = torch.stack((low, high), dim=1).flatten()
+
+    # Vectorized sign and magnitude extraction
+    signs = (combined & 0x08).to(torch.bool)  # Sign bits
+    abs_vals = (combined & 0x07).to(torch.long)  # Magnitude indices
+
+    # Device-aware lookup and sign application
+    kE0M4 = get_e0m4_tensor(device=a.device)
+    values = kE0M4[abs_vals] * torch.where(signs, -1.0, 1.0)
+
+    # Reshape to final form
+    return values.reshape(m, n).to(dtype=dtype)

auto_round/export/export_to_autoround/export_to_nvfp_mxfp.py → auto_round/export/export_to_autoround/export_to_nvfp_mx.py

@@ -44,7 +44,8 @@
 )
 from auto_round.wrapper import WrapperWALayer
 
-from .qlinear_fp import QuantLinear
+from .qlinear_fp import QuantLinear as FpQuantLinear
+from .qlinear_int import QuantLinear as IntQuantLinear
 
 __all__ = [
     "pack_layer",
@@ -94,7 +95,8 @@ def pack_layer(name, model, backend, device=None):
 
     bias = layer.bias is not None
     ##bias = True  ## if using the above, llama3 lambada RTN will be NAN , TODO why?
-    qlayer = QuantLinear(  ##pylint: disable=E1123
+    linear_func = FpQuantLinear if "fp" in data_type else IntQuantLinear
+    qlayer = linear_func(  ##pylint: disable=E1123
         bits,
         group_size,
         in_features,