[Bug tree-optimization/95410] New: Failure to optimize compare next to and properly

gabravier at gmail dot com gcc-bugzilla@gcc.gnu.org
Fri May 29 10:53:44 GMT 2020


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95410

            Bug ID: 95410
           Summary: Failure to optimize compare next to and properly
           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, int y)
{
    if ((unsigned)x >= y)
        return false;

    return (x & 1) == 0;
}

This can be optimized to `return ((unsigned)x < y) & !(x & 1);` (and further to
`return ~x & ((unsigned)x < y);`). This transformation is done by LLVM, but not
by GCC.


More information about the Gcc-bugs mailing list