https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78103
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org
--- Comment #19 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 51211
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51211&action=edit
gcc12-pr78103.patch
Updated untested patch that uses define_insn_and_split in 2 cases instead of
the combine splitters so that it can work around the lack of LOG_LINKS.
The patch doesn't do anything with -mlzcnt, even when bsr or bsr + lea would be
shorter than mov + lzcnt + sub, but I'm afraid we can't do anything about that,
we've lost information whether it is UB on zero or not with -mlzcnt and for
zero input all this is quite unsafe.
