[PATCH] D150646: [clang][X86] Add __cpuidex function to cpuid.h

Thu Aug 3 12:13:32 PDT 2023

aidengrossman added a comment.

I'm not opposed to a revert, but I know some downstream users like MinGW have already adapted to this change so I'm not sure how much headache it would cause them to do a revert.

Maybe I'm not understanding things correctly, but I originally `_MSC_EXTENSIONS` patch as people were enabling the microsoft extensions (thus enabling the builtin) and still including `cpuid.h` which caused an error due to redefining a builtin function. There seems to be another issue there where multiple flags need to be set (`-fms-extensions`, `-fms-compatibility`, and `fms-compatibility-version`) in order to get `_MSC_EXTENSIONS` defined while only passing `fms-extensions` gets the builtin defined, but not the macro. I'm not sure if just passing `-fms-extensions` is even a valid configuration, but it does error out then. I believe that's a separate issue to the auxiliary triple issue you mentioned.

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https://reviews.llvm.org/D150646