[Bug tree-optimization/98909] New: Failure to optimize odd loop pattern

[gabravier at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98909

            Bug ID: 98909
           Summary: Failure to optimize odd loop pattern
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

bool f(int x)
{
    bool odd = false;
    while (x > 0) { x--; odd = !odd; }
    return odd;
}

This can be optimized to `return (x > 0) && ((x & 1) != 0);`. This
transformation is done by LLVM, but not by GCC.