[Bug tree-optimization/124838] __builtin_clzl(0) overoptimization even on targets with native lzcnt instruction

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124838

--- Comment #11 from Drea Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Drea Pinski from comment #10)
> So there is an heurstics for factor_out_conditional_operation on factoring
> out the conversion or not. We should improve those to handle
> CTZ_DEFINED_VALUE_AT_ZERO case and factor out the conversion for that cae.
> as we know phiopt will modify it anyways.

I should mention the reason why the heurstics exists for
factor_out_conditional_operation is specifically for cases like this if the
other value is NOT the one provided by CTZ_DEFINED_VALUE_AT_ZERO (see PR 71016
) :).