macOS_arm64 build about xnnpack

[Maratyszcza]

These changes should be sufficient

[simonmaurer]

any feedback with respect to this?

[Maratyszcza]

Bazel build for ARM64 Mac is currently not supported. CMake build should work.

[simonmaurer]

@Maratyszcza okay thanks for the feedback. issued a pull request in the official TensorFlow repo to allow building on platform macos_arm64 using cmake.

could you give me a hint on where to make changes to allow bazel builds ? already modified the following files:
bazel.rc, BUILD.bazel, build_defs.bzl, third_party/cpuinfo.BUILD, see the changes (inspired by this commit in the official TF repo)

[simonmaurer]

PR to resolve this.
allows compilation for macos_arm64on M1 host using:

bazel build -c opt --config=macos_arm64 :end2end_bench

cross compilation on other platforms (e.g. Linux or macOS_x86-64) does not work yet due to missing toolchains.
at least I get the following errors when building on a macOS_x86-64 platform for macos_arm64:

ERROR: /private/var/tmp/**/**/external/local_config_cc/BUILD:48:19: in cc_toolchain_suite rule @local_config_cc//:toolchain: cc_toolchain_suite '@local_config_cc//:toolchain' does not contain a toolchain for cpu 'darwin_arm64' INFO: Repository cpuinfo instantiated at: /**/**/**/**/xnnpack_simonmaurer/WORKSPACE:66:13: in <toplevel> Repository rule http_archive defined at: /private/var/tmp/**/**/external/bazel_tools/tools/build_defs/repo/http.bzl:336:31: in <toplevel> ERROR: Analysis of target '//:end2end_bench' failed; build aborted: Analysis of target '@local_config_cc//:toolchain' failed