https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127013
--- Comment #3 from Kael Franco <kaelfandrew at gmail dot com> ---
One real world case, which LLVM optimizes for x | CST when (x & CST) != 0.
In tree-ssa-propagate.cc:
```
static void
add_control_edge (edge e)
{
basic_block bb = e->dest;
if (bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
return;
/* If the edge had already been executed, skip it. */
if (e->flags & EDGE_EXECUTABLE)
return;
e->flags |= EDGE_EXECUTABLE;
...
```
