Support break and labeled statements.

frog/leg/ssa/optimize.dart

Index: frog/leg/ssa/optimize.dart
diff --git a/frog/leg/ssa/optimize.dart b/frog/leg/ssa/optimize.dart
index 1f1a029aeaf8bff9407fa4bc6569399abff3be31..5d07e406b03f988987bc4ec019f808533f2ffee6 100644
--- a/frog/leg/ssa/optimize.dart
+++ b/frog/leg/ssa/optimize.dart
@@ -295,13 +295,23 @@ class SsaDeadPhiEliminator {
       }
     }
 
+    recursiveRemove(HPhi phi) {
+      while (!phi.usedBy.isEmpty()) {
+        recursiveRemove(phi.usedBy[0]);

[floitsch, 2012/02/20 19:01:54]

are you sure this can't yield an infinite loop?

[Lasse Reichstein Nielsen, 2012/02/21 13:53:56]

Not absolutely. I guess we could have recursive dependencies between phis in a
loop. I'll have to check.
Alternatively, I can just remove this phi as an input of the ones that uses it,
before removing itself (removePhi doesn't work if the phi has uses, and if we
can have cycles, we would need to break it somehow, so might as well do it
here).

+      }
+      phi.block.removePhi(phi);
+    }
+
     // Remove phis that are not live.
     for (final block in graph.blocks) {
       HPhi current = block.phis.first;
       HPhi next = null;
       while (current != null) {
         next = current.next;
-        if (!livePhis.contains(current)) block.removePhi(current);
+        if (!livePhis.contains(current)) {
+          // Remove any (dead phi) uses of current before removing current.
+          recursiveRemove(current);
+        }
         current = next;
       }
     }