Add CMake for onnx app

[vawale]

Adds CMakeLists.txt file for cmake build of onnx app. The build logic is kept same as the one from corresponding Makefile.

Fixes #8737

[alexreinking]

Thanks for taking a crack at this! We're currently performing some maintenance on the build bots, but I will take a look at this when we're done.

[alexreinking]

Going to see what the buildbots think. Looking at recent logs, it seems protoc was missing from the macOS workers (at least), so that scenario hasn't been tested in a while. I'm curious to see what happens with the new venv support I added to the buildbots.

There probably needs to be a -force_load or equivalent case, but TBQH I'm not convinced that will work with the newer machO formats. I'll bet this app needs to be passed the path to the autoscheduler library like the other apps do.

[alexreinking]

Still waiting on buildbots, but this is what stood out to me on a first pass.

[alexreinking]

Some of the buildbots were missing protoc. Now I see the following errors:

In file included from model.cpp:7:
./denormal_disabler.h:38:18: error: private field 'csr_' is not used [-Werror,-Wunused-private-field]
    unsigned int csr_ = 0;
                 ^
./denormal_disabler.h:39:10: error: private field 'need_restore_' is not used [-Werror,-Wunused-private-field]
    bool need_restore_ = false;
         ^
2 errors generated.
make[2]: *** [/Users/halidenightly/build_bot/worker/halide-testbranch-main-llvm_main-arm-64-osx-make/halide-build/bin/apps/onnx/bin/host/model_cpp.cpython-313-darwin.so] Error 1
make[1]: *** [onnx_test_app] Error 1
make: *** [test_apps] Error 2

[vawale]

Thanks for the review and the follow up fixes. I will look into addressing the comments soon :)

Some of the buildbots were missing protoc. Now I see the following errors:

Ah okay. Should I skip building this app if protoc is not available?

[alexreinking]

@vawale -- while playing with this, I discovered a bunch more changes that needed to be made in other parts of the project. Assuming the buildbots like it at this point, I'm happy to merge.

[alexreinking]

New failures on the mac bots because WebGPU is missing. This is because they're running under launchd now and don't have the environment variables set. This is brittle, so I'm going to do this The Right Way...

Homebrew/homebrew-core#232863

[alexreinking]

This is brittle, so I'm going to do this The Right Way...

Turns out this is too hard. See #8714 .

[alexreinking]

@vawale -- I see that the halide_as_onnx_backend_test is timing out (and that subtests are failing). Does it work for you?

https://buildbot.halide-lang.org/master/#/builders/265/builds/30

[alexreinking]

Seems like halide_as_onnx_backend_test is failing because Adams2019 is thinking for too long.

[vawale]

Seems like halide_as_onnx_backend_test is failing because Adams2019 is thinking for too long.

Yes, I observe the same. The auto-scheduler takes too long.

[alexreinking]

Despite all the workflows failing... none of them are related to this change. Thanks so much for your help!