[lld] lld-link 21.1.0-rc3: undefined reference to _Avx2WmemEnabled #154595
Description
Possible related commit: bbc8346
Windows' ucrt/wchar.h contains:
#if !defined(_M_CEE)
#if (defined(_M_IX86) && !defined(_M_HYBRID_X86_ARM64)) || (defined(_M_X64) && !defined(_M_ARM64EC))
extern int _Avx2WmemEnabled;
__declspec(selectany) int _Avx2WmemEnabledWeakValue = 0;
#if defined(_M_IX86)
#pragma comment(linker, "/alternatename:__Avx2WmemEnabled=__Avx2WmemEnabledWeakValue")
#else
#pragma comment(linker, "/alternatename:_Avx2WmemEnabled=_Avx2WmemEnabledWeakValue")
#endif
#endif
#endif
then later, in wmemchr():
#if !defined(__clang__) || defined(__AVX2__)
if (_Avx2WmemEnabled && _N >= 16)
{
__m256i __v2 = _mm256_broadcastw_epi16(_mm_cvtsi32_si128(_C));
When compiling with AVX2 and then linking a DLL, lld-link fails with
lld-link: undefined reference to _Avx2WmemEnabled
21.1.0-rc1 works fine.