wasm: Add support for WASI threads in CMake build system #71978
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This patch adds a new CMake option, `SWIFT_ENABLE_WASI_THREADS`, to enable building the Standard Library using WASI threads primitives (https://github.com/WebAssembly/wasi-threads). With this option, the Standard Library will be built for the new "wasm32-unknown-wasi-threads" target. We add the new triple because the WASI threads proposal requires extra syscalls and object files compiled to "wasm32-unknown-wasi" and "wasm32-unknown-wasi-threads" are not compatible and cannot be linked together.
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@swift-ci smoke test |
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@swift-ci test WebAssembly |
| @@ -418,7 +422,11 @@ macro(configure_sdk_unix name architectures) | |||
| message(FATAL_ERROR "unsupported arch for WebAssembly: ${arch}") | |||
| endif() | |||
| set(SWIFT_SDK_WASI_ARCH_wasm32_PATH "${SWIFT_WASI_SYSROOT_PATH}") | |||
| set(SWIFT_SDK_WASI_ARCH_wasm32_TRIPLE "wasm32-unknown-wasi") | |||
| if(SWIFT_ENABLE_WASI_THREADS) | |||
| set(SWIFT_SDK_WASI_ARCH_wasm32_TRIPLE "wasm32-unknown-wasi-threads") | |||
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Is there no other way to express this other than using the last triple component? Is this the triple that Clang uses for WASI threads as well? I find it confusing that we have wasm32-unknown-none-wasm with the last triple component denoting the object format, and wasm32-unknown-wasi-threads for denoting a platform feature. OTOH this is not much different from armv7-unknown-linux-musl?
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I followed how wasi-sdk and wasi-libc call the target: https://github.com/WebAssembly/wasi-sdk/blob/f1ebc52a74394cdf885d03bfde13899b3d5c6d2d/wasi-sdk-pthread.cmake#L9
Target triple parser is very complicated... The fourth component of triple can be interpreted as environment or object file format.
https://github.com/llvm/llvm-project/blob/a872a35251b833aaddec2172710ff234236afbd8/llvm/lib/TargetParser/Triple.cpp#L1071-L1076
This patch adds a new CMake option,
SWIFT_ENABLE_WASI_THREADS, to enable building the Standard Library using WASI threads primitives (https://github.com/WebAssembly/wasi-threads). With this option, the Standard Library will be built for the new "wasm32-unknown-wasi-threads" target. We add the new triple with "-threads" environment field because the WASI threads proposal requires extra syscalls and object files compiled to "wasm32-unknown-wasi" and "wasm32-unknown-wasi-threads" are not compatible and cannot be linked together.I chose
wasm32-unknown-wasi-threadsby following wasi-sdk: https://github.com/WebAssembly/wasi-sdk/blob/f1ebc52a74394cdf885d03bfde13899b3d5c6d2d/wasi-sdk-pthread.cmake#L9