enc.cc,msvc: add clang_rt.builtins for __builtin_cpu_* - #185
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Fixes link errors related to `__builtin_cpu_init` and `__builtin_cpu_supports` when using `clang-cl.exe` or `clang.exe` to target the Windows ABI. Issue webmproject#163
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Detection in CMake looked something like: But this only covered |
jzern
marked this pull request as ready for review
September 2, 2026 20:47
hasinoff
reviewed
Sep 2, 2026
| #else | ||
| #pragma comment(lib, "clang_rt.builtins-i386.lib") | ||
| #endif | ||
| #endif |
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Ideally non-clang Windows would return false - this will fail to compile on MSVC, I think.
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MSVC (cl.exe) will not have __i386__ or __x86_64__ defined.
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MSVC (
cl.exe) will not have__i386__or__x86_64__defined.
It fails to link due to the deficient SSE2 check, mentioned in #163 (comment).
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This works in the 3 configurations I tested with Visual Studio 2026:
-G Visual Studio 18 2026 -T ClangCl(clang-cl.exe)-G Visual Studio 18 2026(cl.exe, hits the#else)-G Ninja Multi-Config(clang.exe)
So, later some work can be done to add cl.exe support using the __cpuid(ex) and _xgetbv intrinsics like we do in libwebp.
skal65535
approved these changes
Sep 3, 2026
| #else | ||
| #pragma comment(lib, "clang_rt.builtins-i386.lib") | ||
| #endif | ||
| #endif |
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Fixes link errors related to
__builtin_cpu_initand__builtin_cpu_supportswhen usingclang-cl.exeorclang.exetotarget the Windows ABI.
Issue #163