A change in the way we place TransitionElementKinds in the tree.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index ec23e1971b7923d14b11ca23622cb900dbcbcd24..d61944645950963c8eb34de52bf350a19401a1cd 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -2069,7 +2069,8 @@ HValue* HLoadKeyedGeneric::Canonicalize() {
             index_cache,
             key_load->key(),
             key_load->key(),
-            key_load->elements_kind());
+            key_load->elements_kind(),
+            block()->zone());
         map_check->InsertBefore(this);
         index->InsertBefore(this);
         HLoadFieldByIndex* load = new(block()->zone()) HLoadFieldByIndex(
@@ -2721,6 +2722,142 @@ Representation HPhi::RepresentationFromUseRequirements() {
 }
 
 
+TransitionElementsBookmark::TransitionElementsBookmark(
+    HTransitionElementsKind* transition,
+    Handle<Map> map_from, Handle<Map> map_to, Isolate* isolate)
+    : transition_(transition),
+      from_(map_from),
+      to_(map_to),
+      pessimistic_holey_() {
+
+  // When transition records are created, we have the chance to create map
+  // transitions we might need later. Transitions are unified during
+  // optimization, and we may need to transition from a packed fastmap to a
+  // holey version of same. But we can't create those transitions during
+  // optimization. Do it now, recognizing that when the handle disappears these
+  // maps may be collected if they didn't make it into usage in the optimized
+  // graph.
+
+  // TODO(mvstanton): generalize this service into
+  // "MakeWorstCaseMapForElementsKindTransition" (ie, not "holey")
+  if (IsFastPackedElementsKind(map_to->elements_kind())) {
+    ElementsKind holey_kind = GetHoleyElementsKind(map_to->elements_kind());
+    // The transition might already exist
+    Handle<Map> holey_map_handle(FindClosestElementsTransition(*map_to,
+                                                               holey_kind));
+    ASSERT(!holey_map_handle.is_null());
+    if (holey_map_handle->elements_kind() != holey_kind) {
+      MaybeObject* holey_map = map_to->AddMissingElementsTransitions(
+          holey_kind);
+      holey_map->ToHandle<Map>(&pessimistic_holey_, isolate);
+    } else {
+      pessimistic_holey_ = holey_map_handle;
+    }
+  } else {
+    pessimistic_holey_ = map_to;
+  }
+
+  ASSERT(!pessimistic_holey_.is_null());
+
+  // fill in map_family_
+  // Walk up to the base map from the map_to();
+  Handle<Map> end_map(FindClosestElementsTransition(*map_to,
+                                                TERMINAL_FAST_ELEMENTS_KIND));
+  ASSERT(!end_map.is_null());
+  family_ = end_map;
+}
+
+
+void ArrayInstruction::PrintElementPlacementTo(StringStream* stream) {
+  stream->Add("SITE: block%d %d: ", block()->block_id(),
+              id());
+  PrintTo(stream);
+  stream->Add("\n");
+
+  // Print validness
+  stream->Add("  HOISTABLE: %s\n", hoistable() ? "true" : "false");
+
+  // Print score
+  // stream->Add("  SCORE: (+%d,%d,-%d)\n", score_[0], score_[1], score_[2]);
+
+  // Find the def point for the instruction
+  HValue *element = elements();
+  ASSERT(element != NULL);
+  // Now get the item from the elements
+  ASSERT(element->IsLoadElements());
+  HValue *elements_value = HLoadElements::cast(element)->value();
+  stream->Add("  OBJECT: ");
+  elements_value->PrintNameTo(stream);
+  stream->Add("  ");
+  elements_value->PrintTo(stream);
+  stream->Add(" %s\n", elements_value->IsPhi() ? "PHI" : "");
+  stream->Add("  TRANSITIONS:\n");
+  ElementsKind transitionElementsKind = FAST_SMI_ELEMENTS;
+  for (int i = 0; i < bookmarks(); i++) {
+    TransitionElementsBookmark* b = bookmark(i);
+    stream->Add("    %s", ElementsKindToString(b->elementskind_from()));
+    stream->Add("(0x%p)-> ", *(b->from()));
+    transitionElementsKind = b->elementskind_to();
+    stream->Add("%s", ElementsKindToString(transitionElementsKind));
+    stream->Add("(0x%p)\n", *(b->to()));
+  }
+
+  /*
+  // Print possibly externally computed map
+  const char *signifier = (transitionElementsKind !=
+                           most_general_map()->elements_kind())
+      ? "*" : "";
+  stream->Add("  COMPUTED MOST GENERAL MAP: %s%s(0x%p)\n", signifier,
+              ElementsKindToString(most_general_map()->elements_kind()),
+              most_general_map());
+
+  // Print terminal nodes if available
+
+  stream->Add("  TRANSITION INPUT VALUES:\n");
+  for (int j = 0; j < transition_inputs(); j++) {
+    HValue* node = transition_input(j);
+    stream->Add("    block%d %d: ", node->block()->block_id(), node->id());
+    node->PrintNameTo(stream);
+    stream->Add("  ");
+    node->PrintTo(stream);
+    stream->Add("\n");
+  }
+  */
+}
+
+
+void ArrayInstruction::AddBookmarks(const ZoneList<TransitionElementsBookmark>&
+                                    records) {
+  ASSERT(records.length() > 0);
+  Map* first_to_map = *(records[0].to().location());
+
+  // Doesn't check for duplicates.
+  // The "to" map values should be the same for the whole group
+  for (int i = 0; i < records.length(); i++) {
+    bookmarks_->Add(records[i], zone_);
+    ASSERT(first_to_map == *(records[i].to().location()));
+  }
+
+  // set_most_general_map(first_to_map);
+}
+
+
+Map* ArrayInstruction::map_family() {
+  Map* family = NULL;
+  if (bookmarks()) {
+    family = *(bookmark(0)->family().location());
+  }
+
+#ifdef DEBUG
+  for (int i = 1; i < bookmarks(); i++) {
+    TransitionElementsBookmark* tr = bookmark(i);
+    ASSERT(*(tr->family().location()) == family);
+  }
+#endif
+  return family;
+}
+
+
 // Node-specific verification code is only included in debug mode.
 #ifdef DEBUG