chore: import upstream snapshot with attribution

python/paddle/quantization/observers/abs_max.py

@@ -0,0 +1,95 @@
+# Copyright (c) 2022 PaddlePaddle Authors. 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.
+
+
+import paddle
+
+from ..base_observer import BaseObserver
+from ..factory import ObserverFactory
+
+
+class AbsmaxObserver(ObserverFactory):
+    r"""
+    It collects maximum absolute values of target tensor.
+
+    Args:
+        bit_length(int, optional): Number of bits to represent an quantized integer in binary.
+        dtype(str, optional): The data type of input tensor.
+        name (str, optional): This parameter is used by developers to print debugging information. \
+            For details, please refer to :ref:`api_guide_Name`. Default is None.
+
+    Examples:
+        .. code-block:: pycon
+
+            >>> from paddle.quantization import QuantConfig
+            >>> from paddle.quantization.quanters import FakeQuanterWithAbsMaxObserver
+            >>> quanter = FakeQuanterWithAbsMaxObserver(moving_rate=0.99)
+            >>> q_config = QuantConfig(activation=quanter, weight=quanter)
+    """
+
+    def __init__(self, quant_bits=8):
+        super().__init__(quant_bits=quant_bits)
+
+    def _get_class(self):
+        return AbsmaxObserverLayer
+
+
+class AbsmaxObserverLayer(BaseObserver):
+    """
+    Per-tensor abs max quantizer.
+    """
+
+    INIT_ABS_MAX = 1e-7
+
+    def __init__(self, layer, quant_bits=8):
+        super().__init__()
+        self._quant_bits = quant_bits
+        self.abs_max_val = paddle.to_tensor(AbsmaxObserverLayer.INIT_ABS_MAX)
+        self._max = None
+        self._scale = None
+        self._zero_point = None
+
+    def forward(self, input):
+        self._min, self._max = self.cal_min_max(input)
+        return input
+
+    def cal_min_max(self, inputs):
+        abs_max_val = paddle.max(paddle.abs(inputs))
+        if self._max is not None:
+            abs_max_val = paddle.maximum(
+                abs_max_val, self._max.cast(inputs.dtype)
+            )
+        return 0, abs_max_val
+
+    def bit_length(self):
+        return self._quant_bits
+
+    def quant_axis(self):
+        return -1
+
+    def cal_thresholds(self):
+        """Compute thresholds for MAX function."""
+        if self._scale is None:
+            self._scale = self._max
+        self._zero_point = paddle.zeros_like(self._scale)
+
+    def scales(self):
+        """Return output scales."""
+        if self._scale is None:
+            self.cal_thresholds()
+        return self._scale
+
+    def zero_points(self):
+        """Return output zero points."""
+        return self._zero_point