gcc/testsuite/gcc.dg/tree-ssa/pr87205-2.c

/* { dg-options "-O2 -fdump-tree-optimized" } */

void f(int);
void h(unsigned i)
{
  switch (i) {
    default: __builtin_unreachable();
    case 0: f(42); break;
    case 1: f(42); break;
    case 2: f(42); break;
    case 3: f(42); break;
    case 4: f(42); break;
    case 5: f(42); break;
  }
} 

/* { dg-final { scan-tree-dump-not "if" "optimized" } } */
/* { dg-final { scan-tree-dump-not "switch" "optimized" } } */