[Bug target/106471] Strange code generation for __builtin_ctzl()

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106471

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The xor is due to X86_TUNE_AVOID_FALSE_DEP_FOR_BMI setting:

/* X86_TUNE_AVOID_FALSE_DEP_FOR_BMI: Avoid false dependency
   for bit-manipulation instructions.  */
DEF_TUNE (X86_TUNE_AVOID_FALSE_DEP_FOR_BMI, "avoid_false_dep_for_bmi",
          m_SANDYBRIDGE | m_CORE_AVX2 | m_TREMONT | m_ALDERLAKE | m_LUJIAZUI
     | m_GENERIC)

See PR 62011 for more details on that one.