[CMSIS-NN] code generator for softmax (apache#8833)

CMakeLists.txt

@@ -48,6 +48,7 @@ tvm_option(USE_TF_COMPILE_FLAGS "Build with TensorFlow's compile flags." OFF)
 tvm_option(USE_TF_TVMDSOOP "Build with TensorFlow TVMDSOOp" OFF)
 tvm_option(USE_FALLBACK_STL_MAP "Use TVM's POD compatible Map" OFF)
 tvm_option(USE_ETHOSN "Build with Arm Ethos-N" OFF)
+tvm_option(USE_CMSISNN "Build with Arm CMSIS-NN" OFF)
 tvm_option(INDEX_DEFAULT_I64 "Defaults the index datatype to int64" ON)
 tvm_option(USE_LIBBACKTRACE "Build libbacktrace to supply linenumbers on stack traces" AUTO)
 tvm_option(BUILD_STATIC_RUNTIME "Build static version of libtvm_runtime" OFF)
@@ -418,6 +419,7 @@ include(cmake/modules/ROCM.cmake)
 include(cmake/modules/LLVM.cmake)
 include(cmake/modules/Micro.cmake)
 include(cmake/modules/contrib/EthosN.cmake)
+include(cmake/modules/contrib/CMSISNN.cmake)
 include(cmake/modules/contrib/BLAS.cmake)
 include(cmake/modules/contrib/CODEGENC.cmake)
 include(cmake/modules/contrib/DNNL.cmake)

cmake/modules/contrib/CMSISNN.cmake

@@ -0,0 +1,22 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+
+if(USE_CMSISNN)
+  message(STATUS "Build with CMSIS-NN support")
+  file(GLOB RELAY_CONTRIB_CMSISNN_SRCS src/relay/backend/contrib/cmsisnn/*.cc)
+  list(APPEND COMPILER_SRCS ${RELAY_CONTRIB_CMSISNN_SRCS})
+endif(USE_CMSISNN)

python/tvm/driver/tvmc/composite_target.py

@@ -24,6 +24,7 @@
 
 from tvm.relay.op.contrib.arm_compute_lib import partition_for_arm_compute_lib
 from tvm.relay.op.contrib.ethosn import partition_for_ethosn
+from tvm.relay.op.contrib.cmsisnn import partition_for_cmsisnn
 from tvm.relay.op.contrib.bnns import partition_for_bnns
 from tvm.relay.op.contrib.vitis_ai import partition_for_vitis_ai
 
@@ -49,6 +50,10 @@
         "config_key": None,
         "pass_pipeline": partition_for_arm_compute_lib,
     },
+    "cmsis-nn": {
+        "config_key": None,
+        "pass_pipeline": partition_for_cmsisnn,
+    },
     "ethos-n77": {
         "config_key": "relay.ext.ethos-n.options",
         "pass_pipeline": partition_for_ethosn,

python/tvm/relay/backend/__init__.py

@@ -16,3 +16,4 @@
 # under the License.
 """Backend codegen modules for relay."""
 from . import compile_engine
+from .contrib import cmsisnn

python/tvm/relay/backend/contrib/__init__.py

@@ -0,0 +1,18 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+"""external backend codegen modules for relay."""
+from . import cmsisnn

python/tvm/relay/backend/contrib/cmsisnn/__init__.py

@@ -0,0 +1,18 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+"""CMSIS-NN codegen modules for relay."""
+from . import codegen

python/tvm/relay/backend/contrib/cmsisnn/codegen.py

@@ -0,0 +1,134 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+"""Codegen for CMSIS-NN"""
+import tvm
+from tvm import relay
+from tvm.relay.expr_functor import ExprVisitor
+
+
+class GenerateTIR(ExprVisitor):
+    """Generates TIR module containing TIR primfuncs corresponding to the Relay operators.
+    Note: Relay operator to primfunc mapping may not be 1:1.
+    """
+
+    def __init__(self, name):
+        super().__init__()
+        self.name = name
+        self.tir_mod = None
+        self.scale = 1.0 / 256
+
+    def call_contains_op(self, call, op_name):
+        if not isinstance(call.op, tvm.ir.op.Op):
+            return False
+        if call.op.name != op_name:
+            return False
+        return True
+
+    def is_quantized_softmax(self, call):
+        """Checks for the following relay sequence
+        a = qnn.dequantize(in, scale, zero_point)
+        b = nn.softmax(a)
+        c = qnn.quantize(c, scale, zero_point)
+        """
+        if not self.call_contains_op(call, "qnn.quantize"):
+            return False
+        softmax_call = call.args[0]
+        if not self.call_contains_op(softmax_call, "nn.softmax"):
+            return False
+        dequantize_call = softmax_call.args[0]
+        if not self.call_contains_op(dequantize_call, "qnn.dequantize"):
+            return False
+        self.scale = dequantize_call.args[1].data.numpy().item(0)
+        return True
+
+    def emit_softmax_tir(self, call):
+        """Generates TIR extern_call for softmax"""
+        shape = call.checked_type.shape  # NHWC
+        dtype = call.checked_type.dtype
+        ir_builder = tvm.tir.ir_builder.create()
+        in_buf = tvm.tir.decl_buffer(shape=shape, dtype=dtype)
+        out_buf = tvm.tir.decl_buffer(shape=shape, dtype=dtype)
+
+        trailing_dim = len(shape) - 1
+        num_rows = 1
+        for dim in range(trailing_dim):
+            num_rows *= shape[dim]
+        row_size = shape[trailing_dim]
+        ir_builder.emit(
+            tvm.tir.call_extern(
+                dtype,
+                "arm_softmax_s8",
+                in_buf.data,
+                num_rows,
+                row_size,
+                self.scale,
+                out_buf.data,
+            )
+        )
+        prim_func = tvm.tir.PrimFunc([in_buf, out_buf], ir_builder.get())
+        prim_func = prim_func.with_attr("global_symbol", self.name)
+        prim_func = prim_func.with_attr("tir.noalias", True)
+        self.tir_mod = tvm.IRModule({self.name: prim_func})
+
+    def visit_call(self, call):
+        """Iterates over the relay operators within relay external function"""
+        super().visit_call(call)
+        if self.is_quantized_softmax(call):
+            self.emit_softmax_tir(call)
+
+    def generate_tir(self, func):
+        self.visit(func)
+        return self.tir_mod
+
+
+def relay_to_tir(name, func):
+    """Lower a Relay function to TIR for the CMSIS-NN target.
+
+    The Relay function should only contain operations supported
+    by the CMSIS-NN target. This is enforced by the graph partitioner
+    for CMSIS-NN.
+
+    Parameters
+    ----------
+    name: str
+        Name of the external relay function
+    func : tvm.relay.Function
+        The Relay function to lower.
+
+    Returns
+    -------
+    mod : tvm.IRModule
+        The lowered TIR module.
+
+    """
+    return GenerateTIR(name).generate_tir(func)
+
+
+@tvm.register_func("relay.ext.cmsisnn")
+def cmsisnn_compiler(relay_func):
+    """It compiles Relay's external function into equivalent TIR
+    and subsequently converts that into 'c' code. During the 'c'
+    code generation, it embeds CMSIS-NN APIs for the corresponding
+    operators.
+    """
+    mod = tvm.IRModule()
+    mod["main"] = relay_func
+    mod = relay.transform.InferType()(mod)
+    func_name = relay_func.attrs["global_symbol"]
+    tir_mod = relay_to_tir(func_name, mod["main"])
+    cmsisnn_runtime = tvm._ffi.get_global_func("runtime.module.cmsisnn.create")
+    return cmsisnn_runtime(tir_mod)

python/tvm/relay/op/contrib/cmsisnn.py

@@ -68,11 +68,15 @@ def softmax_pattern():
 
     def check_quantized_softmax(extract):
         """Check if softmax is supported by CMSIS-NN."""
+        dequantize_call = extract.args[0].args[0]
+        scale = extract.args[1].data.numpy().item(0)
+        zero_point = extract.args[2].data.numpy().item(0)
 
         # check for dtypes of quantize and dequantize
         return (
-            extract.attrs.out_dtype == "int8"
-            and extract.args[0].args[0].args[0].checked_type.dtype == "int8"
+            (scale == 1.0 / 256 and zero_point == -128)
+            and extract.attrs.out_dtype == "int8"
+            and dequantize_call.args[0].checked_type.dtype == "int8"
         )
 
     return [