Enable MainActor in embedded concurrency, add ExecutorImpl.cpp

[MaxDesiatov]

ExecutorImpl.cpp should be moved from SWIFT_RUNTIME_CONCURRENCY_NONEMBEDDED_C_SOURCES to SWIFT_RUNTIME_CONCURRENCY_C_SOURCES. This way we can also include ExecutorImpl.swift and use PlatformExecutorCooperative.swift in embedded concurrency for WASI.

[ktoso]

Looks ok I think

[MaxDesiatov]

@swift-ci smoke test

[MaxDesiatov]

@swift-ci build toolchain

[MaxDesiatov]

@swift-ci smoke test macos

[kubamracek]

@al45tair could you take a look here?

[al45tair]

My concern with this is that there might be people using Embedded Swift with the existing CooperativeGlobalExecutor from the static archive, and adding ExecutorImpl.cpp will clash with that. That's why I didn't do this previously.

Also, you'll need to update the copy of the Concurrency CMakeLists.txt in the Runtimes directory at the top level (since we currently have two separate build systems).

[MaxDesiatov]

@swift-ci smoke test

[MaxDesiatov]

My concern with this is that there might be people using Embedded Swift with the existing CooperativeGlobalExecutor from the static archive, and adding ExecutorImpl.cpp will clash with that. That's why I didn't do this previously.

I've updated the changes to be isolated to Wasm only, where it is expected. No other users should be impacted.

Also, you'll need to update the copy of the Concurrency CMakeLists.txt in the Runtimes directory at the top level (since we currently have two separate build systems).

Runtimes doesn't build anything for Embedded Swift, and no new files were added, neither any of the files were removed, so there are no relevant changes to be reflected there.

[MaxDesiatov]

@swift-ci smoke test

[MaxDesiatov]

@swift-ci test windows

[MaxDesiatov]

@swift-ci test windows