[Hexagon] Do not auto-build apps when building TVM

[kparzysz-quic]

The Hexagon cmakes have recently become unwieldy due to a complex network of dependencies between various automatically built components. This was in large part because of trying to automatically build some apps, which then tried to build TVM runtimes again, but with their own configurations.

This patch removes the ability to automatically build any Hexagon-related apps from the main TVM build. The following cmake options are now deprecated:

• USE_HEXAGON_LAUNCHER
• USE_HEXAGON_PROXY_RPC

In order to build the binaries needed for HexagonLauncher from tvm.contrib.hexagon:

• Build TVM+runtime for x86, with codegen for Hexagon enabled. This can be done via USE_HEXAGON_DEVICE=sim or target.
• Build Android runtime and tvm_rpc with -DUSE_RPC=ON, -DUSE_CPP_RPC=ON, and -DUSE_HEXAGON_RPC=ON.
• Build Hexagon runtime with -DUSE_HEXAGON_RPC=ON, and -DBUILD_STATIC_RUNTIME=ON.

Thanks for contributing to TVM! Please refer to guideline https://tvm.apache.org/docs/contribute/ for useful information and tips. After the pull request is submitted, please request code reviews from Reviewers by @ them in the pull request thread.

[kparzysz-quic]

cc: @mehrdadh

[kparzysz-quic]

This replaces #9904.

[Lunderberg]

I like the idea of simplifying the build process, but I'm worried that this would make it more difficult for developers to test changes. This PR would reduce the complexity of the existing cmake setup, but I think it would result in passing that complexity to the developer to manually handle.

Build details, as I understand them.

• Three TVM builds are required. (Host, connected Android, connected Hexagon)
• Each of the three builds has different values for the RPC and static/dynamic options.
• All three builds must have the same values for several build variables.
  • Hexagon: USE_HEXAGON_SDK and USE_HEXAGON_ARCH
  • Android: USE_ANDROID_TOOLCHAIN
• All three builds must have be built from the same version of TVM.
• All three builds must output to the same location (currently $BUILD_DIR/apps/hexagon_*).

Brainstorming on options

• Option 1: Top-level TVM CMake launches the three independent builds as external projects
  • Current implementation on main.
  • Pro: Developer can run make && run_my_test.py to rebuild all three tests in a single step.
  • Con: Difficult to manage setup.
• Option 2: Developer launches the three independent builds
  • Current implementation in this PR.
  • Pro: Easier to manage cmake setup.
  • Con: Interactions between the three builds must be handled by each developer, either manually or by writing a wrapper build script.
  • Con: Removes the app from the TVM framework. Compiling TVM is no longer sufficient to use tvm.contrib.hexagon.
• Option 3: App Cmake launches all three independent builds
  • Pro: Developer can run tests from a single location
  • Pro: Includes occur only in one direction, from the app to the TVM build.
  • Con: Removes the app from the TVM framework. Compiling TVM is no longer sufficient to use tvm.contrib.hexagon.

Between the high-level options, I'd prefer Option 1, since it would maintain the same developer-facing interactions. Thoughts?

[kparzysz-quic]

I chatted with Mehrdad and we're going with an app that will build the Hexagon RPC support, i.e. option 3 in your list.

[mehrdadh]

Thanks for making this change! Just few minor things to make sure tests are passing.

[mehrdadh]

change HEXAGON_API_BINARY_DIR to this to be compatible with current HexagonLauncher design:
set(HEXAGON_API_BINARY_DIR "${CMAKE_BINARY_DIR}/../../../build/hexagon_rpc")

This is with the assumption of building this CmakeLists.txt under apps/hexagon_api/build. Not the best solution, but we need to make sure everything is copied to build/hexagon_rpc.

[kparzysz-quic]

This is going to be really fragile. Instead I propose a flag USE_OUTPUT_BINARY_DIR that could be set to any location, including .../build/hexagon_rpc.

[mehrdadh]

@kparzysz-quic makes sense. Thanks!

[mehrdadh]

@kparzysz-quic I tested with hardware and it LGTM!