[Bug tree-optimization/105314] ifcvt regression in noce_try_store_flag_mask

[christophm30 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105314

--- Comment #1 from Christoph Müllner <christophm30 at gmail dot com> ---
A first analysis in noce_try_store_flag_mask() showed the following observation
in case of the failing conversion into the branchless sequence:

* if_info->b == const0_rtx holds
* rtx_equal_p (if_info->a, if_info->x) does not hold

Assuming that the generic form would be "x := c ? x : 0", the second
observation seems odd.