Bazel can do the selective build mechanism for C API.

https://github.com/tensorflow/tensorflow/blob/master/tensorflow/lite/c/BUILD#L115

The tflite_custom_c_library build rule can generate the selectively built TensorFlow Lite C library.

Cool, I replaced tflite_custom_c_library build rule with

tflite_custom_c_library(
    name = "selectively_built_c_api_test_lib",
    testonly = 1,
    models = [
        "//tensorflow/lite:testdata/mymodel1.bin",
        "//tensorflow/lite:testdata/mymodel2.bin",
    ],
    visibility = ["//visibility:private"],
)

Then, built armeabi-v7a with

bazel build -c opt --config=android_arm //tensorflow/lite/c:selectively_built_c_api_test_lib

and arm64-v8a with

bazel build -c opt --config=android_arm64 //tensorflow/lite/c:selectively_built_c_api_test_lib

Tested the generated .so files with my app in Android Studio and it built successfully.

Binaries reduction:

• arm64-v8a: 2.5 MB to 1.5 MB
• armeabi-v7a: 1.9 MB to 1.7 MB

Is there any reason why binary for armeabi-v7a reduces less than arm64-v8a?

Thanks for pointing me to the right direction @abattery.

I haven't looked at the details. Looks like the pruned op kernels consume more spaces at arm64-8va.

Hey, I still couldn't make it work.

When I build TensorFlow Lite using selective build to generate the library and use the library with JNI, my app in Android Studio builds. However, when I flash it to the mobile it cannot load the library. For selective build I use:

bazel build -c opt --config=android_arm64 //tensorflow/lite/c:selectively_built_c_api_test_lib

In order to verify whether the issue was related to the selective build or not, I also tried building without selective build. Again, I could build my app in Android Studio using the generated library, however it did not work when I flashed it to the mobile. For default build, I use:

bazel build -c opt --config=android_arm64 //tensorflow/lite/c:tensorflowlite_c

Before, I used to build the library using tensorflow/lite/tools/build_aar.sh and I could use the generated library in my app successfully. Successful build:

./tensorflow/lite/tools/build_aar.sh --target_archs=arm64-v8a

The issue is that, as stated in Reduce Binary Size, selective build is not supported for C API and I need to reduce my binary size.

I have the following questions: what is the difference between using bazel build -c opt --config=android_arm64 //tensorflow/lite/c:tensorflowlite_c and ./tensorflow/lite/tools/build_aar.sh --target_archs=arm64-v8a? Am I missing anything in tensorflowlite_c build rule in order to make it behave like ./tensorflow/lite/tools/build_aar.sh?

Thanks!

Could you share how the compiled shared object is not working on the mobile app? If possible, could you share the error message you've got?

Hey @abattery, thanks for your reply.

Could you share how the compiled shared object is not working on the mobile app? If possible, could you share the error message you've got?

Unfortunately, I don't have access to the java source code of my mobile app. I am just replacing the compiled shared object of the app and the error it gives me is not very descriptive. It is something like WARNING: Could not load libMyLib.so.

On the other hand, I think I figured out what was my issue. As I said, I don't have access to the java source code, so I need to use a specific name for the compiled shared object which was already being used by the java part. My issue was that I was compiling the shared object with tensorflowlite_c build rule and then renaming the generated shared object. My app couldn't use the compiled shared object because of the renaming, so I replaced tensorflowlite_c build rule name by my_lib_specific_name and it generated the shared object with the proper name. This time, it worked with my mobile app.

Then, I tried to do the same for the selective build in order to reduce the library size. Initially, it did not work because I was trying to use selectively_built_c_api_test_lib build rule by its own. However, as pointed here the correct way of doing it (I think) is using tensorflowlite_c build rule replacing

":c_api",
":c_api_experimental",

with

"selectively_built_c_api_test_lib",

I did it and it worked. The shared object reduced from 2.5MB to 1.1MB. I used it with my mobile app and it worked!

Here is the diff with the necessary changes:

Again, thanks for your help @abattery.

Great, thanks for sharing your success!

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