From 069cfb7d24e9ae003478d9b5a777811e470eb278 Mon Sep 17 00:00:00 2001
From: Guanghua Yu <742925032@qq.com>
Date: Thu, 17 Aug 2023 15:19:08 +0800
Subject: [PATCH] add abs_max observer (#1786)

---
 paddleslim/quant/observers/__init__.py |   2 +
 paddleslim/quant/observers/abs_max.py  | 102 +++++++++++++++++++++++++
 2 files changed, 104 insertions(+)
 create mode 100644 paddleslim/quant/observers/abs_max.py

diff --git a/paddleslim/quant/observers/__init__.py b/paddleslim/quant/observers/__init__.py
index c2f4e4c8..7ab3b723 100644
--- a/paddleslim/quant/observers/__init__.py
+++ b/paddleslim/quant/observers/__init__.py
@@ -17,6 +17,7 @@ from .kl import KLObserver
 from .mse import MSEObserver
 from .emd import EMDObserver
 from .avg import AVGObserver
+from .abs_max import AbsmaxObserver
 from .mse_weight import MSEChannelWiseWeightObserver
 from .abs_max_weight import AbsMaxChannelWiseWeightObserver
 
@@ -27,6 +28,7 @@ __all__ = [
     "EMDObserver",
     "AVGObserver",
     "MSEWeightObserver",
+    "AbsmaxObserver",
     "MSEChannelWiseWeightObserver",
     "AbsMaxChannelWiseWeightObserver",
 ]
diff --git a/paddleslim/quant/observers/abs_max.py b/paddleslim/quant/observers/abs_max.py
new file mode 100644
index 00000000..10cdf298
--- /dev/null
+++ b/paddleslim/quant/observers/abs_max.py
@@ -0,0 +1,102 @@
+# Copyright (c) 2023 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 numpy as np
+import paddle
+from .uniform import UniformObserver
+from paddle.quantization.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:: python
+            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(AbsmaxObserver, self).__init__(quant_bits=quant_bits)
+
+    def _get_class(self):
+        return AbsmaxObserverLayer
+
+
+class AbsmaxObserverLayer(UniformObserver):
+    def __init__(
+            self,
+            layer,
+            quant_bits=8, ):
+        super(AbsmaxObserverLayer, self).__init__(quant_bits=quant_bits)
+        self._quant_bits = quant_bits
+        self._layer = layer
+        self._scale = None
+        self._zero_point = None
+        self._min = None
+        self._max = paddle.to_tensor(1e-7, dtype="float32")
+        self.step = 0
+
+    def forward(self, inputs):
+        """ Calculate forward pass.
+        """
+        self._min, self._max = self.cal_min_max(inputs)
+        return inputs
+
+    def cal_min_max(self, inputs):
+        abs_max_val = paddle.max(paddle.abs(inputs.cast("float32")))
+        abs_max_val = paddle.maximum(abs_max_val, self._max)
+        return 0, abs_max_val
+
+    def cal_thresholds(self):
+        """ Compute thresholds for MAX function.
+        """
+        self._scale, self._zero_point = self.cal_scales_zero_points()
+
+    def min_value(self) -> float:
+        return self._min
+
+    def max_value(self) -> float:
+        return self._max
+
+    def bit_length(self):
+        """ Return the bit length of quantized data.
+        """
+        return self._quant_bits
+
+    def quant_axis(self):
+        """ Return quantization axis.
+        """
+        return -1
+
+    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.
+        """
+        if self._zero_point is None:
+            self.cal_thresholds()
+        return self._zero_point
-- 
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