tools: global-dynamic TLS for PIC sysroot builds - #125
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local-exec TLS makes PIC libc++'s errno accesses unrelocatable when errno is imported (side modules, e.g. CPython C++ extensions): "R_WASM_MEMORY_ADDR_TLS_SLEB cannot be used against an undefined symbol errno". Gate the model on CMAKE_POSITION_INDEPENDENT_CODE (PIC -> global-dynamic), matching wasixcc's PIC codegen.
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Pull request overview
This PR updates the WASIX Clang CMake toolchain files to select a TLS model that is compatible with PIC builds intended for use as side modules (where errno may be imported), avoiding relocation failures caused by local-exec TLS.
Changes:
- Gate
-ftls-model=onCMAKE_POSITION_INDEPENDENT_CODE: PIC builds useglobal-dynamic, non-PIC builds keeplocal-exec. - Apply the same TLS-model selection logic across the standard, EH, and exnref-EH toolchain variants.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| tools/clang-wasix.cmake_toolchain | Switch TLS model to global-dynamic when CMAKE_POSITION_INDEPENDENT_CODE is enabled. |
| tools/clang-wasix-eh.cmake_toolchain | Same TLS-model gating for the EH toolchain variant. |
| tools/clang-wasix-exnref-eh.cmake_toolchain | Same TLS-model gating for the exnref+EH toolchain variant. |
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local-exec TLS makes PIC libc++'s errno accesses unrelocatable when errno is imported (side modules, e.g. CPython C++ extensions):
Gate the model on
CMAKE_POSITION_INDEPENDENT_CODE(PIC -> global-dynamic), matching wasixcc's PIC codegen.