[Bug target/98567] Failure to optimize using ZF flag from blsi

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98567

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 49901
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49901&action=edit
gcc11-pr98567.patch

Untested fix.