Adjust TLS in wasip3 with threads - #867
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This is a refinement of the previous implementation in WebAssembly#858 and is intended to be the dual of bytecodealliance/wasm-tools#2596 for wasi-libc. Notably the details of what exactly is exported from each shared object is now encapsulated and local to wasi-libc as opposed to needing toolchain integration which removes the need for changes to Clang or LLD. The main change here is that the previous inline array of `__wasilibc_library_tls_info`, which was constructed by `wasm-tools component link`, is now defined by wasi-libc itself. The representation here has changed slightly since TLS size/align isn't `const`-knowable at this time (now it's a function pointer to learn that), and the dynamic linker will now arrange for an array of these structures to be visible to libc and use. This extra level of indirection means that each shared object exports its own information and those are all woven into a single list for wasi-libc to read.
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This'll fail until bytecodealliance/wasm-tools#2596 is landed/published as a heads up |
dicej
approved these changes
Aug 11, 2026
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This is a refinement of the previous implementation in #858 and is intended to be the dual of bytecodealliance/wasm-tools#2596 for wasi-libc. Notably the details of what exactly is exported from each shared object is now encapsulated and local to wasi-libc as opposed to needing toolchain integration which removes the need for changes to Clang or LLD. The main change here is that the previous inline array of
__wasilibc_library_tls_info, which was constructed bywasm-tools component link, is now defined by wasi-libc itself. The representation here has changed slightly since TLS size/align isn'tconst-knowable at this time (now it's a function pointer to learn that), and the dynamic linker will now arrange for an array of these structures to be visible to libc and use. This extra level of indirection means that each shared object exports its own information and those are all woven into a single list for wasi-libc to read.