rename to backend/interface.h (#285)

Summary:
Pull Request resolved: #285

this file is more about the interface between the backend and the executor runtime. The original name is `backend.h` and was renamed to `backend_registry.h` during refactor. But the backend registery is a really small part.

Techincally we can seperate out backend_registery, but it's just a few lines and feel like it might be overkill. Users also need to include two header files too and doesn't seem worth the effort

Reviewed By: JacobSzwejbka

Differential Revision: D48399818

fbshipit-source-id: f873e25d1cea12c457087b9011dfd5cbd3b2a47e

Author: cccclai

README.md

@@ -54,9 +54,6 @@ executorch
 ├── backends                        #  1st party backend implementations.
 |   ├── xnnpack
 |   ├── vulkan
-|   ├── backend_api.py              # TODO move to exir/backend
-|   ├── backend_details.py          # TODO move to exir/backend
-|   ├── partioner.py                # TODO move to exir/backend
 ├── build                           #  Utilities for managing the build system.
 ├── bundled_program                 #  Utilities for attaching reference inputs and outputs to models. TODO move to extension
 ├── codegen                         #  Tooling to autogenerate bindings between kernels and the runtime. TODO move to tool
@@ -67,6 +64,7 @@ executorch
 |   ├── export
 |   ├── models
 ├── exir                            #  Ahead of time library, model capture and lowering apis.
+|   ├── backend                     #  Backend delegate ahead of time APIs
 |   ├── capture                     #  Program capture.
 |   ├── dialects                    #  Op sets for various dialects in the export process.
 |   ├── emit                        #  Conversion from ExportedProgram to Executorch execution instructions.
@@ -87,7 +85,7 @@ executorch
 |   ├── quantized
 ├── profiler                        #  Utilities for profiling. TODO delete in favor of ETDump in sdk/
 ├── runtime                         #  core cpp runtime of executorch
-|   ├── backend                     #  Backend definition and registration.
+|   ├── backend                     #  Backend delegate runtime APIs
 |   ├── core                        #  Core structures used across all levels of the runtime
 |   ├── executor                    #  Model loading, initalization, and execution.
 |   ├── kernel                      #  Kernel registration and management.

backends/qnnpack/QNNPackBackend.cpp

@@ -10,7 +10,7 @@
 #include <executorch/backends/qnnpack/qnnpack_schema_generated.h>
 #include <executorch/backends/xnnpack/runtime/utils/utils.h>
 #include <executorch/backends/xnnpack/threadpool/threadpool.h>
-#include <executorch/runtime/backend/backend_registry.h>
+#include <executorch/runtime/backend/interface.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/evalue.h>
 #include <executorch/runtime/core/exec_aten/util/scalar_type_util.h>

backends/qnnpack/targets.bzl

@@ -63,7 +63,7 @@ def define_common_targets():
         deps = [
             "//executorch/runtime/core/exec_aten/util:scalar_type_util",
             "//executorch/runtime/core/exec_aten/util:tensor_util",
-            "//executorch/runtime/backend:backend_registry",
+            "//executorch/runtime/backend:interface",
             "//executorch/backends/xnnpack/threadpool:threadpool",
             "//executorch/backends/xnnpack:dynamic_quant_utils",
             "//{prefix}caffe2/aten/src/ATen/native/quantized/cpu/qnnpack:pytorch_qnnpack".format(

backends/vulkan/TARGETS

@@ -17,7 +17,7 @@ runtime.cxx_library(
     deps = [
         "//caffe2:torch_vulkan_graph",
         "//executorch/backends/vulkan/serialization/schema:vk_delegate_schema",
-        "//executorch/runtime/backend:backend_registry",
+        "//executorch/runtime/backend:interface",
     ],
 )
 

backends/vulkan/VulkanBackend.cpp

@@ -9,7 +9,7 @@
 #include <ATen/native/vulkan/graph/Arithmetic.h>
 #include <ATen/native/vulkan/graph/Graph.h>
 #include <executorch/backends/vulkan/serialization/schema/schema_generated.h>
-#include <executorch/runtime/backend/backend_registry.h>
+#include <executorch/runtime/backend/interface.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/evalue.h>
 #include <executorch/runtime/platform/profiler.h>

backends/xnnpack/runtime/XNNExecutor.h

@@ -9,7 +9,7 @@
 #pragma once
 
 #include <executorch/backends/xnnpack/runtime/XNNStatus.h>
-#include <executorch/runtime/backend/backend_registry.h>
+#include <executorch/runtime/backend/interface.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/exec_aten/util/tensor_util.h>
 

backends/xnnpack/runtime/XNNPACKBackend.cpp

@@ -7,7 +7,7 @@
  */
 
 #include <executorch/backends/xnnpack/runtime/XNNCompiler.h>
-#include <executorch/runtime/backend/backend_registry.h>
+#include <executorch/runtime/backend/interface.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/evalue.h>
 #include <executorch/runtime/platform/profiler.h>

backends/xnnpack/targets.bzl

@@ -10,7 +10,7 @@ def define_common_targets():
         exported_headers = ["runtime/utils/utils.h"],
         deps = [
             "//executorch/runtime/core/exec_aten:lib",
-            "//executorch/runtime/backend:backend_registry",
+            "//executorch/runtime/backend:interface",
         ],
         visibility = [
             "//executorch/backends/xnnpack/...",
@@ -72,7 +72,7 @@ def define_common_targets():
             third_party_dep("XNNPACK"),
             ":xnnpack_schema",
             ":dynamic_quant_utils",  # TODO Use (1) portable for choose_qparams(), (2) xnnpack for quantize_per_tensor(),
-            "//executorch/runtime/backend:backend_registry",
+            "//executorch/runtime/backend:interface",
             "//executorch/backends/xnnpack/threadpool:threadpool",
             "//executorch/runtime/core/exec_aten/util:tensor_util",
         ],

exir/backend/test/demos/rpc/ExecutorBackend.cpp

@@ -14,7 +14,7 @@
 #include <memory>
 
 #include <executorch/extension/data_loader/buffer_data_loader.h>
-#include <executorch/runtime/backend/backend_registry.h>
+#include <executorch/runtime/backend/interface.h>
 #include <executorch/runtime/core/error.h>
 #include <executorch/runtime/core/evalue.h>
 #include <executorch/runtime/executor/method.h>

exir/backend/test/demos/rpc/ExecutorBackendRegister.cpp

@@ -7,7 +7,7 @@
  */
 
 #include <executorch/exir/backend/test/demos/rpc/ExecutorBackend.h>
-#include <executorch/runtime/backend/backend_registry.h>
+#include <executorch/runtime/backend/interface.h>
 #include <executorch/runtime/core/error.h>
 
 namespace torch {