[Bug tree-optimization/96703] New: Failure to optimize combined comparison of variables and of variable with 0 to two comparisons with 0

[gabravier at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96703

            Bug ID: 96703
           Summary: Failure to optimize combined comparison of variables
                    and of variable with 0 to two comparisons with 0
           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)
{
    return x > y && y == 0;
}

This can be optimized to `return (y == 0) && (x > 0);` (This transformation
doesn't by itself make the code faster, but it probably helps with pipelined
CPUs (avoids dependency on both variables for the first comparison) and looks
like it would most likely make other optimizations easier). This transformation
is done by LLVM, but not by GCC.