How to add external header files during bazel/tensorflow build

Question

I am trying to add external header file (like OpenCL header file) for some experimentation for tensorflow. I tried to add this into BUILD file under tensorflow/core/BUILD fi

Answer 1

You have to add the files as a dependency of this rule.

IIUC, you have the following structure:

tensorflow/
  BUILD
  WORKSPACE
  tensorflow/
    core/
      BUILD
  third_party/
    include -> /opt/opencl/CL # or something like that

You want to expose the .h files in a way Bazel can understand/depend on, so open up the tensorflow/BUILD file and add the following:

cc_library(
    name = "opencl",
    hdrs = glob(["third_party/include/*.h"]),
    visibility = ["//visibility:public"],
)

This creates a C++ library from the .h files under third_party/include, which can be depended on from anywhere in the source tree.

Now go to your tensorflow/core/BUILD file and add a dependency to the cc_library there:

cc_library(
    name = "all_kernels",
    visibility = ["//visibility:public"],
    copts = tf_copts() + ["-Ithird_party/include"],
    deps = [
        "//:opencl", 
        # plus any other deps
    ],
)

Setting copts just changes the flags when gcc is run. Adding //:opencl to the dependencies tells Bazel to make those files available when gcc is run.