[Transform] Delete remove_identity to avoid conflicts with RemoveIdentityOps

src/finn/transformation/remove_identity.py

-# Copyright (c) 2020, Xilinx
-# All rights reserved.
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are met:
-#
-# * Redistributions of source code must retain the above copyright notice, this
-#   list of conditions and the following disclaimer.
-#
-# * Redistributions in binary form must reproduce the above copyright notice,
-#   this list of conditions and the following disclaimer in the documentation
-#   and/or other materials provided with the distribution.
-#
-# * Neither the name of FINN nor the names of its
-#   contributors may be used to endorse or promote products derived from
-#   this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
-# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
-# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
-# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from finn.transformation import Transformation
-
-
-def _is_identity(node, model):
-    if node.op_type == "Mul":
-        scale = model.get_initializer(node.input[1])
-        if scale is not None:
-            return (scale == 1).all()
-    elif node.op_type == "Add":
-        bias = model.get_initializer(node.input[1])
-        if bias is not None:
-            return (bias == 0).all()
-    return False
-
-
-class RemoveIdentity(Transformation):
-    """Remove nodes that apply identity ops from the graph, including:
-    * Multiply by 1
-    * Add 0
-    ."""
-
-    def apply(self, model):
-        graph = model.graph
-        node_ind = 0
-        graph_modified = False
-        for node in graph.node:
-            node_ind += 1
-            if _is_identity(node, model):
-                node_src = node.input[0]
-                node_dst = node.output[0]
-                graph.node.remove(node)
-                model.rename_tensor(node_dst, node_src)
-                graph_modified = True
-        return (model, graph_modified)