[Bug tree-optimization/118637] [12/13/14/15 Regression] gcc fails to optimize unsigned division by 2 to shift right by 1

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118637

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 60263
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60263&action=edit
gcc15-pr118637.patch

So far lightly tested patch.

Note, these functions don't compute the normal x ? 32 - __builtin_clz (x) : 0
but instead x / 2 ? 32 - __builtin_clz (x / 2) : 0.