Check elimination now sets known successor branch of HCompareObjectEqAndBranch (correctness fix).

src/hydrogen-check-elimination.cc

Index: src/hydrogen-check-elimination.cc
diff --git a/src/hydrogen-check-elimination.cc b/src/hydrogen-check-elimination.cc
index a7c45ac31cdd03a0aacc61a19419fd34cb8c9636..52a549299a24e7913a59aeb656e7e55c87c013fc 100644
--- a/src/hydrogen-check-elimination.cc
+++ b/src/hydrogen-check-elimination.cc
@@ -88,6 +88,10 @@ class HCheckTable : public ZoneObject {
         ReduceCompareMap(HCompareMap::cast(instr));
         break;
       }
+      case HValue::kCompareObjectEqAndBranch: {
+        ReduceCompareObjectEqAndBranch(HCompareObjectEqAndBranch::cast(instr));
+        break;
+      }
       case HValue::kTransitionElementsKind: {
         ReduceTransitionElementsKind(
             HTransitionElementsKind::cast(instr));
@@ -479,6 +483,23 @@ class HCheckTable : public ZoneObject {
     instr->block()->MarkSuccEdgeUnreachable(unreachable_succ);
   }
 
+  void ReduceCompareObjectEqAndBranch(HCompareObjectEqAndBranch* instr) {
+    MapSet maps_left = FindMaps(instr->left()->ActualValue());
+    if (maps_left == NULL) return;
+    MapSet maps_right = FindMaps(instr->right()->ActualValue());
+    if (maps_right == NULL) return;
+    MapSet intersection = maps_left->Intersect(maps_right, phase_->zone());
+    if (intersection->size() > 0) return;
+
+    TRACE(("Marking redundant CompareObjectEqAndBranch #%d at B%d as false\n",
+        instr->id(), instr->block()->block_id()));
+    int succ = 1;
+    instr->set_known_successor_index(succ);
+
+    int unreachable_succ = 1 - succ;
+    instr->block()->MarkSuccEdgeUnreachable(unreachable_succ);
+  }
+
   void ReduceTransitionElementsKind(HTransitionElementsKind* instr) {
     MapSet maps = FindMaps(instr->object()->ActualValue());
     // Can only learn more about an object that already has a known set of maps.