wasip2: Improve "command" startup flow #710
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This commit is an improvement to the WASIp2 target which changes how the interface `wasi:cli/run` is defined and exported. Previously the `wasm32-wasip2` target would define a `_start` wasm export which required the use of the WASIp1-to-WASIp2 adapter to hook it up to `wasi:cli/run`. This meant that despite libc not actually using any WASIp2 APIs the adapter was still used. The purpose of this commit is to change this. The changes made here are: * The linker-level `_start` symbol now has a wasm-level export name of `wasi:cli/run@0.2.0#run`. This means that `_start` isn't a wasm-level export any more, meaning there's nothing for the adapter to import. * The signature of the C-level `_start` function is now different based on WASI version (returns an `int` in WASIp2, nothing on WASIp1) * The `crt1-command.o` object file now contains type information for `wasi:cli/run` (which previously wasn't present anywhere in wasi-libc). This means that when this object is linked in `wit-component` will know what to do after linking. The end result is that binaries are now produced entirely without the WASIp1-to-WASIp2 adapter and linking with `-Wl,--wasi-adapter=none`, for example, produces a working binary. Another minor change made in this commit is that the `crt1-*.c` files are now included in `clang-format` like all other source files. Build-wise this requires the usage of `wasm-tools` at build-time to embed type information in the clang-produced object file for `crt1-command.o`.
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This commit is an improvement to the WASIp2 target which changes how the interface
wasi:cli/runis defined and exported. Previously thewasm32-wasip2target would define a_startwasm export which required the use of the WASIp1-to-WASIp2 adapter to hook it up towasi:cli/run. This meant that despite libc not actually using any WASIp2 APIs the adapter was still used. The purpose of this commit is to change this.The changes made here are:
_startsymbol now has a wasm-level export name ofwasi:cli/run@0.2.0#run. This means that_startisn't a wasm-level export any more, meaning there's nothing for the adapter to import._startfunction is now different based on WASI version (returns anintin WASIp2, nothing on WASIp1)crt1-command.oobject file now contains type information forwasi:cli/run(which previously wasn't present anywhere in wasi-libc). This means that when this object is linked inwit-componentwill know what to do after linking.The end result is that binaries are now produced entirely without the WASIp1-to-WASIp2 adapter and linking with
-Wl,--wasi-adapter=none, for example, produces a working binary.Another minor change made in this commit is that the
crt1-*.cfiles are now included inclang-formatlike all other source files.Build-wise this requires the usage of
wasm-toolsat build-time to embed type information in the clang-produced object file forcrt1-command.o.