xtensa: Add BUILD file and workspace for nnlib_hifi4 (#2239)

The optimized kernel selection expects a lib target to be present in third_party/xtensa/nnlib_hifi4 so provide an alias there that maps to an external repository.

Provide a build file to be used as the root of the nnlib_hifi4 repository and add to WORKSPACE. No build is done using this lib yet as there is no xtensa toolchain available in bazel just yet.

BUG=None

WORKSPACE

@@ -16,18 +16,21 @@
 workspace(name = "tflite_micro")
 
 load("//tensorflow:workspace.bzl", "workspace")
+
 workspace()
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 
 # compile_commands.json generator
 http_archive(
     name = "hedron_compile_commands",
-    url = "https://github.com/hedronvision/bazel-compile-commands-extractor/archive/1266d6a25314d165ca78d0061d3399e909b7920e.tar.gz",
-    strip_prefix = "bazel-compile-commands-extractor-1266d6a25314d165ca78d0061d3399e909b7920e",
     sha256 = "bacabfe758676fdc19e4bea7c4a3ac99c7e7378d259a9f1054d341c6a6b44ff6",
+    strip_prefix = "bazel-compile-commands-extractor-1266d6a25314d165ca78d0061d3399e909b7920e",
+    url = "https://github.com/hedronvision/bazel-compile-commands-extractor/archive/1266d6a25314d165ca78d0061d3399e909b7920e.tar.gz",
 )
+
 load("@hedron_compile_commands//:workspace_setup.bzl", "hedron_compile_commands_setup")
+
 hedron_compile_commands_setup()
 
 http_archive(
@@ -40,32 +43,38 @@ http_archive(
 # Read the Python package dependencies of the build environment. To modify
 # them, see //third_party:python_requirements.in.
 load("@rules_python//python:pip.bzl", "pip_parse")
+
 pip_parse(
     name = "tflm_pip_deps",
     requirements_lock = "//third_party:python_requirements.txt",
 )
 
 # Create repositories for each Python package dependency.
 load("@tflm_pip_deps//:requirements.bzl", "install_deps", "requirement")
+
 install_deps()
 
 http_archive(
-  name = "pybind11_bazel",
-  strip_prefix = "pybind11_bazel-faf56fb3df11287f26dbc66fdedf60a2fc2c6631",
-  urls = ["https://github.com/pybind/pybind11_bazel/archive/faf56fb3df11287f26dbc66fdedf60a2fc2c6631.zip"],
-  sha256 = "a185aa68c93b9f62c80fcb3aadc3c83c763854750dc3f38be1dadcb7be223837",
+    name = "pybind11_bazel",
+    sha256 = "a185aa68c93b9f62c80fcb3aadc3c83c763854750dc3f38be1dadcb7be223837",
+    strip_prefix = "pybind11_bazel-faf56fb3df11287f26dbc66fdedf60a2fc2c6631",
+    urls = ["https://github.com/pybind/pybind11_bazel/archive/faf56fb3df11287f26dbc66fdedf60a2fc2c6631.zip"],
 )
 
 http_archive(
-  name = "pybind11",
-  build_file = "@pybind11_bazel//:pybind11.BUILD",
-  strip_prefix = "pybind11-2.10.0",
-  urls = ["https://github.com/pybind/pybind11/archive/refs/tags/v2.10.0.tar.gz"],
-  sha256 = "eacf582fa8f696227988d08cfc46121770823839fe9e301a20fbce67e7cd70ec",
+    name = "pybind11",
+    build_file = "@pybind11_bazel//:pybind11.BUILD",
+    sha256 = "eacf582fa8f696227988d08cfc46121770823839fe9e301a20fbce67e7cd70ec",
+    strip_prefix = "pybind11-2.10.0",
+    urls = ["https://github.com/pybind/pybind11/archive/refs/tags/v2.10.0.tar.gz"],
 )
 
 load("@pybind11_bazel//:python_configure.bzl", "python_configure")
-python_configure(name = "local_config_python", python_version = "3")
+
+python_configure(
+    name = "local_config_python",
+    python_version = "3",
+)
 
 load("//python:py_pkg_cc_deps.bzl", "py_pkg_cc_deps")
 
@@ -81,3 +90,11 @@ py_pkg_cc_deps(
     libs = ["tensorflow/libtensorflow_framework.so.2"],
     pkg = requirement("tensorflow-cpu"),
 )
+
+# Optimized kernel deps
+http_archive(
+    name = "nnlib_hifi4",
+    build_file = "@tflite_micro//third_party/xtensa/nnlib_hifi4:nnlib_hifi4.BUILD",
+    strip_prefix = "nnlib-hifi4-34f5f995f28d298ae2b6e2ba6e76c32a5cb34989",
+    urls = ["https://github.com/foss-xtensa/nnlib-hifi4/archive/34f5f995f28d298ae2b6e2ba6e76c32a5cb34989.zip"],
+)

third_party/xtensa/nnlib_hifi4/BUILD

@@ -0,0 +1,7 @@
+alias(
+    name = "nnlib_hifi4_lib",
+    actual = "@nnlib_hifi4//:lib",
+    visibility = [
+        "//visibility:public",
+    ],
+)

third_party/xtensa/nnlib_hifi4/nnlib_hifi4.BUILD

@@ -0,0 +1,43 @@
+constraint_setting(
+    name = "compatible_constraint",
+)
+
+# Set this constraint_value on your platform to indicate compatiblity with this
+# library.
+constraint_value(
+    name = "compatible",
+    constraint_setting = ":compatible_constraint",
+    visibility = [
+        "//visibility:public",
+    ],
+)
+
+cc_library(
+    name = "lib",
+    srcs = glob(["xa_nnlib/algo/**/*.c"]),
+    hdrs = glob([
+        "xa_nnlib/algo/**/*.h",
+        "xa_nnlib/include/**/*.h",
+    ]),
+    copts = ["-Wno-unused-parameter"],
+    defines = [
+        "NNLIB_V2=1",
+        "MODEL_INT16=1",
+        "EIGEN_NO_MALLOC=1",
+        "hifi4=1",
+    ],
+    includes = [
+        "xa_nnlib",
+        "xa_nnlib/algo/common/include",
+        "xa_nnlib/algo/kernels",
+        "xa_nnlib/algo/ndsp/hifi4/include",
+        "xa_nnlib/include",
+        "xa_nnlib/include/nnlib",
+    ],
+    target_compatible_with = [
+        ":compatible",
+    ],
+    visibility = [
+        "//visibility:public",
+    ],
+)