More misc. rodinia opts

• Make GCM not spill ParallelReduce phis.
• Fix unification for inter-device communication.
• Make notion of parallel indices sets more flexible, and use in infer parallel reduce.
• Misc. schedule tweaks.

hercules_opt/src/gcm.rs

@@ -883,6 +883,13 @@ fn spill_clones(
                         init == *b
                             && editor.func().schedules[a.idx()].contains(&Schedule::ParallelReduce)
                     })
+                    .unwrap_or(false)
+                && !editor.func().nodes[a.idx()]
+                    .try_phi()
+                    .map(|(_, data)| {
+                        data.contains(b)
+                            && editor.func().schedules[a.idx()].contains(&Schedule::ParallelReduce)
+                    })
                     .unwrap_or(false))
     });