[Bug tree-optimization/126698] New: Fold ceil (X / 2^C) ==/!= 0 -> X ==/!= 0

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126698

            Bug ID: 126698
           Summary: Fold ceil (X / 2^C) ==/!= 0   ->   X ==/!= 0
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: easyhack, missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
  Target Milestone: ---

int f (unsigned x) { return ((x >> 4) + ((x & 15) != 0)) == 0; }

Currently generates for aarch64 -O2:
f:
        tst     w0, 15
        lsr     w0, w0, 4
        cinc    w0, w0, ne
        cmp     w0, 0
        cset    w0, eq
        ret

but can generate just:
f:
        cmp     w0, #0
        cset    w0, eq
        ret