Dynamically detect libgcc-vs-libunwind #8028
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When native unwinding information is enabled Wasmtime will use the `__register_frame` API on Unix platforms to inform the runtime of the unwinding information generated for wasm modules. This function, however, has a different interface in libgcc vs libunwind. This means that we need to detect which is being used and adapt our calls to it appropriately. Previously this decision was static. FreeBSD and Linux glibc would assume libgcc and everything else was assumed to be libunwind. It's possible to use libgcc on other platforms, however, such as with musl. The goal of this PR is to make the detection here more robust. Specifically this PR now probes for a symbol at runtime rather than relying on a compile-time decision. That way we can see what we got at runtime and make the decision then. Closes bytecodealliance#7997
pchickey
approved these changes
Feb 29, 2024
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When native unwinding information is enabled Wasmtime will use the
__register_frameAPI on Unix platforms to inform the runtime of the unwinding information generated for wasm modules. This function, however, has a different interface in libgcc vs libunwind. This means that we need to detect which is being used and adapt our calls to it appropriately.Previously this decision was static. FreeBSD and Linux glibc would assume libgcc and everything else was assumed to be libunwind. It's possible to use libgcc on other platforms, however, such as with musl. The goal of this PR is to make the detection here more robust.
Specifically this PR now probes for a symbol at runtime rather than relying on a compile-time decision. That way we can see what we got at runtime and make the decision then.
Closes #7997