[Bug tree-optimization/24689] New: store_ccp is missing an opportunity!?

["kazu at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

Consider:

extern void bar (unsigned int);

int
foo (void)
{
  char buf[1] = { 3 };
  const char *p = buf;
  const char **q = &p;
  unsigned int ch;
  switch (**q)
    {
    case 1:  ch = 5; break;
    default: ch = 0; break;
    }

#if 1
  bar (ch);
#endif
  return ch;
}

This function should be optimized to "return 0;", but it isn't.

Interestingly, if you change "#if 1" to "#if 0", you are going to get
this optimized.

The testcase is derived from PR 20583.


-- 
           Summary: store_ccp is missing an opportunity!?
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kazu at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24689