Add Vela codebase

 - Added modules ethosu.vela and ethosu.mlw_codec.
 - Added README and various configuration files.

Change-Id: I3690f8c8f5966306ecddaeb2793c30ca9c6e2eee
diff --git a/ethosu/vela/supported_operators.py b/ethosu/vela/supported_operators.py
new file mode 100644
index 0000000..23135f8
--- /dev/null
+++ b/ethosu/vela/supported_operators.py
@@ -0,0 +1,243 @@
+# Copyright (C) 2020 Arm Limited or its affiliates. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# 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
+#
+# 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.
+
+
+# Description:
+# The SupportedOperators class which is a collection of all supported operators and parameter checks.
+
+from .data_type import BaseType
+
+
+class SupportedOperators:
+    def __init__(self):
+        # Categorised lists of supported operators
+        self.npu_pre_ops = set(("QuantizedResizeBilinear", "SplitSliceRead"))
+        self.convolution_ops = set(("Conv2DBiasAct", "Conv2D", "QuantizedConv2D", "Conv2DBackpropInputSwitched"))
+        self.depthwise_convolution_ops = set(
+            ("DepthwiseConv2dBiasAct", "DepthwiseConv2dNative", "QuantizedDepthwiseConv2D")
+        )
+        self.max_pooling_ops = set(("QuantizedMaxPool", "MaxPool", "MaxPoolAct"))
+        self.avg_pooling_ops = set(("QuantizedAvgPool", "AvgPool", "AvgPoolAct"))
+        self.pooling_ops = self.max_pooling_ops | self.avg_pooling_ops
+        self.fc_vector_products = set(("QuantizedMatMul", "MatMul", "FullyConnectedAct"))
+        self.mac_main_ops = (
+            # convolutions
+            self.convolution_ops
+            # depth-wise convolutions
+            | self.depthwise_convolution_ops
+            # pooling
+            | self.pooling_ops
+            # FC layers
+            | self.fc_vector_products
+            # RNN/LSTM/GRU
+            | set(("BlockLSTM"))
+        )
+        self.elem_wise_main_ops = set(
+            (
+                # element-wise
+                "AddAct",
+                "MulAct",
+                "SubAct",
+                "QuantizedAdd",
+                "QuantizedSub",
+                "QuantizedMul",
+                "Mul",
+                "Add",
+                "Sub",
+                "Minimum",
+                "Maximum",
+            )
+        )
+        self.activation_ops = set(
+            ("QuantizedRelu", "QuantizedRelu1", "QuantizedRelu6", "Relu", "Relu6", "ReluN1To1", "Sigmoid", "Tanh")
+        )
+        self.npu_post_ops = (
+            # activation functions
+            self.activation_ops
+            # concatenation write direction
+            | set(("ConcatSliceWrite"))
+            # bias add and batch norm
+            | set(("QuantizedBiasAdd", "Requantize", "QuantizedBatchNorm", "BiasAdd", "FusedBatchNorm"))
+        )
+        self.split_ops = set(("Split", "StridedSlice", "Slice", "UnpackReshaped", "Unpack"))
+        self.concat_ops = set(("Concat", "ConcatV2", "QuantizedConcat", "ConcatTFLite", "PackReshaped", "Pack"))
+        self.memory_only_ops = (
+            set(("Squeeze", "Reshape", "QuantizedReshape", "ExpandDims")) | self.concat_ops | self.split_ops
+        )
+        self.supported_fused_activations = set(("Relu", "Relu6", "ReluN1To1", "Tanh", "Sigmoid"))
+        self.supported_operators = (
+            self.npu_pre_ops | self.mac_main_ops | self.elem_wise_main_ops | self.npu_post_ops | self.memory_only_ops
+        )
+        # Setup supported operator restriction checkers
+        self.supported_operator_restrictions = {}
+        self.supported_operator_restrictions.update(
+            {op: self.check_convolution_restrictions for op in self.convolution_ops}
+        )
+        self.supported_operator_restrictions.update(
+            {op: self.check_depthwise_convolution_restrictions for op in self.depthwise_convolution_ops}
+        )
+        self.supported_operator_restrictions.update({op: self.check_pooling_restrictions for op in self.pooling_ops})
+        self.supported_operator_restrictions.update(
+            {op: self.check_vector_product_restrictions for op in self.fc_vector_products}
+        )
+        self.supported_operator_restrictions.update(
+            {op: self.check_element_wise_restrictions for op in self.elem_wise_main_ops}
+        )
+        self.supported_operator_restrictions.update(
+            {op: self.check_memory_only_restrictions for op in self.memory_only_ops}
+        )
+
+    def is_operator_supported(self, op):
+        if op.type not in self.supported_operators:
+            return False
+        if not self.check_generic_restrictions(op):
+            return False
+        if op.type in self.supported_operator_restrictions:
+            return self.supported_operator_restrictions[op.type](op)
+        return True
+
+    def check_generic_restrictions(self, op):
+        # check fully defined shapes
+        for t in op.inputs + op.outputs:
+            if not t.has_fully_defined_shape():
+                print("Warning:", op, "has inputs/outputs of undefined shape, placing on CPU")
+                return False
+
+        # check data type
+        tensors = [t for t in op.get_ifm_ifm2_weights_ofm() if t is not None]
+        if not tensors:
+            tensors = op.inputs
+        for t in tensors:
+            if not (t.dtype.type & BaseType.Int):
+                return False
+            if t.element_size() > 2 and op.type != "Requantize":
+                return False
+            # check size
+            if any(dim > 65536 for dim in t.shape):
+                return False
+
+        # check fused activations
+        if (
+            "fused_activation_function" in op.attrs
+            and op.attrs["fused_activation_function"] is not None
+            and op.attrs["fused_activation_function"] not in self.supported_fused_activations
+        ):
+            return False
+        return True
+
+    def check_convolution_restrictions(self, op):
+        # check stride
+        if op.attrs["stride_w"] > 2 or op.attrs["stride_h"] > 2:
+            return False
+
+        # check dilation
+        dilation_w_factor = op.attrs.get("dilation_w_factor", 1)
+        dilation_h_factor = op.attrs.get("dilation_h_factor", 1)
+        if dilation_w_factor > 2 or dilation_h_factor > 2:
+            return False
+
+        # check data type
+        ifm_tensor, _, weight_tensor, _ = op.get_ifm_ifm2_weights_ofm()
+        if weight_tensor.element_size() > 1:
+            return False
+
+        # check kernel size
+        dilated_weight_w = weight_tensor.shape[0] + (weight_tensor.shape[0] - 1) * (dilation_w_factor - 1)
+        dilated_weight_h = weight_tensor.shape[1] + (weight_tensor.shape[1] - 1) * (dilation_h_factor - 1)
+        if (
+            dilated_weight_w > 64
+            or dilated_weight_h > 64
+            or dilated_weight_w * dilated_weight_h * weight_tensor.shape[2] > 127 * 65536
+        ):
+            return False
+
+        # check batch size
+        if ifm_tensor.shape[0] != 1:
+            return False
+        return True
+
+    def check_depthwise_convolution_restrictions(self, op):
+        # check depth
+        ifm_tensor, _, _, ofm_tensor = op.get_ifm_ifm2_weights_ofm()
+        if op.attrs["depth_multiplier"] > 1 and not (
+            (ifm_tensor.shape[3] == 1) and (ofm_tensor.shape[3] == op.attrs["depth_multiplier"])
+        ):
+            return False
+        return self.check_convolution_restrictions(op)
+
+    def check_pooling_restrictions(self, op):
+        # check stride
+        if op.attrs["stride_w"] > 2 or op.attrs["stride_h"] > 2:
+            return False
+
+        # check data type
+        ifm_tensor, _, _, ofm_tensor = op.get_ifm_ifm2_weights_ofm()
+        if ifm_tensor.dtype != ofm_tensor.dtype:
+            return False
+
+        # check batch size
+        if ifm_tensor.shape[0] != 1:
+            return False
+
+        if op.type in self.avg_pooling_ops:
+            # check kernel size
+            if op.attrs["padding"] == b"SAME" and (op.attrs["filter_width"] > 8 or op.attrs["filter_height"] > 8):
+                return False
+            if op.attrs["padding"] == b"VALID" and (op.attrs["filter_width"] > 256 or op.attrs["filter_height"] > 256):
+                return False
+
+        if op.type in self.max_pooling_ops:
+            # check data type
+            if not ifm_tensor.dtype == ofm_tensor.dtype:
+                return False
+            # check kernel size
+            if op.attrs["filter_width"] > 256 or op.attrs["filter_height"] > 256:  # any padding
+                return False
+        return True
+
+    def check_vector_product_restrictions(self, op):
+        # check data type
+        ifm_tensor, _, weight_tensor, _ = op.get_ifm_ifm2_weights_ofm()
+        if weight_tensor.element_size() > 1:
+            return False
+
+        return True
+
+    def check_element_wise_restrictions(self, op):
+        # check data type
+        ifm_tensor, ifm2_tensor, _, ofm_tensor = op.get_ifm_ifm2_weights_ofm()
+        if op.type in ("Minimum", "Maximum") and ifm_tensor.dtype != ofm_tensor.dtype:
+            return False
+
+        # check batch size
+        if (len(ifm_tensor.shape) > 2 and ifm_tensor.shape[0] != 1) or (
+            len(ifm2_tensor.shape) > 2 and ifm2_tensor.shape[0] != 1
+        ):
+            return False
+
+        # check scalar size
+        if (hasattr(ifm_tensor.values, "__len__") and len(ifm_tensor.values) > 1) or (
+            hasattr(ifm2_tensor.values, "__len__") and len(ifm2_tensor.values) > 1
+        ):
+            return False
+        return True
+
+    def check_memory_only_restrictions(self, op):
+        # check stride size
+        if op.type == "StridedSlice":
+            if len(op.inputs) > 3 and any(stride != 1 for stride in op.inputs[3].values):
+                return False
+        return True