[Bug libgcc/105920] New: __builtin_cpu_supports ("f16c") should check AVX

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105920

            Bug ID: 105920
           Summary: __builtin_cpu_supports ("f16c") should check AVX
           Product: gcc
           Version: 11.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgcc
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
  Target Milestone: ---

libgcc has

  if (ecx & bit_F16C)
    set_feature (FEATURE_F16C);
  if (ecx & bit_RDRND)
    set_feature (FEATURE_RDRND);
  if (ecx & bit_XSAVE)
    set_feature (FEATURE_XSAVE);
  if (avx_usable)
    {    
      if (ecx & bit_AVX)
        set_feature (FEATURE_AVX);
      if (ecx & bit_FMA)
        set_feature (FEATURE_FMA);
    }    

F16C should be enabled only if AVX is usable since F16C requires AVX.