Reset trunk to 3.24.35.4

src/hydrogen-check-elimination.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 30 matching lines @@
 // For code de-uglification.
 #define TRACE(x) if (FLAG_trace_check_elimination) PrintF x
 
 namespace v8 {
 namespace internal {
 
 typedef UniqueSet<Map>* MapSet;
 
 struct HCheckTableEntry {
   HValue* object_;  // The object being approximated. NULL => invalid entry.
-  HInstruction* check_;  // The last check instruction.
-  MapSet maps_;          // The set of known maps for the object.
-  bool is_stable_;
+  HValue* check_;   // The last check instruction.
+  MapSet maps_;     // The set of known maps for the object.
 };
 
 
-// The main data structure used during check elimination, which stores a
+// The main datastructure used during check elimination, which stores a
 // set of known maps for each object.
 class HCheckTable : public ZoneObject {
  public:
   static const int kMaxTrackedObjects = 10;
 
   explicit HCheckTable(HCheckEliminationPhase* phase)
     : phase_(phase),
       cursor_(0),
       size_(0) {
   }
@@ skipping 29 matching lines @@
       case HValue::kCheckMapValue: {
         ReduceCheckMapValue(HCheckMapValue::cast(instr));
         break;
       }
       case HValue::kCheckHeapObject: {
         ReduceCheckHeapObject(HCheckHeapObject::cast(instr));
         break;
       }
       default: {
         // If the instruction changes maps uncontrollably, drop everything.
-        if (instr->CheckChangesFlag(kOsrEntries)) {
-          Reset();
-        } else if (instr->CheckChangesFlag(kMaps)) {
-          KillUnstableEntries();
+        if (instr->CheckGVNFlag(kChangesMaps) ||
+            instr->CheckGVNFlag(kChangesOsrEntries)) {
+          Kill();
         }
       }
       // Improvements possible:
       // - eliminate redundant HCheckSmi, HCheckInstanceType instructions
       // - track which values have been HCheckHeapObject'd
     }
 
     return this;
   }
 
-  // Support for global analysis with HFlowEngine: Merge given state with
-  // the other incoming state.
-  static HCheckTable* Merge(HCheckTable* succ_state, HBasicBlock* succ_block,
-                            HCheckTable* pred_state, HBasicBlock* pred_block,
-                            Zone* zone) {
-    if (pred_state == NULL || pred_block->IsUnreachable()) {
-      return succ_state;
-    }
-    if (succ_state == NULL) {
-      return pred_state->Copy(succ_block, pred_block, zone);
-    } else {
-      return succ_state->Merge(succ_block, pred_state, pred_block, zone);
-    }
-  }
-
-  // Support for global analysis with HFlowEngine: Given state merged with all
-  // the other incoming states, prepare it for use.
-  static HCheckTable* Finish(HCheckTable* state, HBasicBlock* block,
-                             Zone* zone) {
-    if (state == NULL) {
-      block->MarkUnreachable();
-    }
-    return state;
-  }
-
- private:
-  // Copy state to successor block.
+  // Global analysis: Copy state to successor block.
   HCheckTable* Copy(HBasicBlock* succ, HBasicBlock* from_block, Zone* zone) {
     HCheckTable* copy = new(phase_->zone()) HCheckTable(phase_);
     for (int i = 0; i < size_; i++) {
       HCheckTableEntry* old_entry = &entries_[i];
       HCheckTableEntry* new_entry = &copy->entries_[i];
+      // TODO(titzer): keep the check if this block dominates the successor?
       new_entry->object_ = old_entry->object_;
+      new_entry->check_ = NULL;
       new_entry->maps_ = old_entry->maps_->Copy(phase_->zone());
-      new_entry->is_stable_ = old_entry->is_stable_;
-      // Keep the check if the existing check's block dominates the successor.
-      if (old_entry->check_ != NULL &&
-          old_entry->check_->block()->Dominates(succ)) {
-        new_entry->check_ = old_entry->check_;
-      } else {
-        // Leave it NULL till we meet a new check instruction for this object
-        // in the control flow.
-        new_entry->check_ = NULL;
-      }
     }
     copy->cursor_ = cursor_;
     copy->size_ = size_;
 
-    // Create entries for succ block's phis.
-    if (!succ->IsLoopHeader() && succ->phis()->length() > 0) {
-      int pred_index = succ->PredecessorIndexOf(from_block);
-      for (int phi_index = 0;
-           phi_index < succ->phis()->length();
-           ++phi_index) {
-        HPhi* phi = succ->phis()->at(phi_index);
-        HValue* phi_operand = phi->OperandAt(pred_index);
-
-        HCheckTableEntry* pred_entry = copy->Find(phi_operand);
-        if (pred_entry != NULL) {
-          // Create an entry for a phi in the table.
-          copy->Insert(phi, NULL, pred_entry->maps_->Copy(phase_->zone()),
-                       pred_entry->is_stable_);
-        }
-      }
-    }
-
     // Branch-sensitive analysis for certain comparisons may add more facts
     // to the state for the successor on the true branch.
     bool learned = false;
-    if (succ->predecessors()->length() == 1) {
-      HControlInstruction* end = succ->predecessors()->at(0)->end();
-      bool is_true_branch = end->SuccessorAt(0) == succ;
+    HControlInstruction* end = succ->predecessors()->at(0)->end();
+    if (succ->predecessors()->length() == 1 && end->SuccessorAt(0) == succ) {
       if (end->IsCompareMap()) {
+        // Learn on the true branch of if(CompareMap(x)).
         HCompareMap* cmp = HCompareMap::cast(end);
         HValue* object = cmp->value()->ActualValue();
         HCheckTableEntry* entry = copy->Find(object);
-        if (is_true_branch) {
-          // Learn on the true branch of if(CompareMap(x)).
-          if (entry == NULL) {
-            copy->Insert(object, cmp, cmp->map(), cmp->is_stable());
-          } else {
-            MapSet list = new(phase_->zone()) UniqueSet<Map>();
-            list->Add(cmp->map(), phase_->zone());
-            entry->maps_ = list;
-            entry->check_ = cmp;
-            entry->is_stable_ = cmp->is_stable();
-          }
+        if (entry == NULL) {
+          copy->Insert(object, cmp->map());
         } else {
-          // Learn on the false branch of if(CompareMap(x)).
-          if (entry != NULL) {
-            entry->maps_->Remove(cmp->map());
-          }
+          MapSet list = new(phase_->zone()) UniqueSet<Map>();
+          list->Add(cmp->map(), phase_->zone());
+          entry->maps_ = list;
         }
         learned = true;
-      } else if (is_true_branch && end->IsCompareObjectEqAndBranch()) {
+      } else if (end->IsCompareObjectEqAndBranch()) {
         // Learn on the true branch of if(CmpObjectEq(x, y)).
         HCompareObjectEqAndBranch* cmp =
           HCompareObjectEqAndBranch::cast(end);
         HValue* left = cmp->left()->ActualValue();
         HValue* right = cmp->right()->ActualValue();
         HCheckTableEntry* le = copy->Find(left);
         HCheckTableEntry* re = copy->Find(right);
         if (le == NULL) {
           if (re != NULL) {
-            copy->Insert(left, NULL, re->maps_->Copy(zone), re->is_stable_);
+            copy->Insert(left, NULL, re->maps_->Copy(zone));
           }
         } else if (re == NULL) {
-          copy->Insert(right, NULL, le->maps_->Copy(zone), le->is_stable_);
+          copy->Insert(right, NULL, le->maps_->Copy(zone));
         } else {
           MapSet intersect = le->maps_->Intersect(re->maps_, zone);
           le->maps_ = intersect;
           re->maps_ = intersect->Copy(zone);
         }
         learned = true;
       }
       // Learning on false branches requires storing negative facts.
     }
 
     if (FLAG_trace_check_elimination) {
       PrintF("B%d checkmaps-table %s from B%d:\n",
              succ->block_id(),
              learned ? "learned" : "copied",
              from_block->block_id());
       copy->Print();
     }
 
     return copy;
   }
 
-  // Merge this state with the other incoming state.
+  // Global analysis: Merge this state with the other incoming state.
   HCheckTable* Merge(HBasicBlock* succ, HCheckTable* that,
-                     HBasicBlock* pred_block, Zone* zone) {
-    if (that->size_ == 0) {
-      // If the other state is empty, simply reset.
-      Reset();
-    } else {
-      int pred_index = succ->PredecessorIndexOf(pred_block);
-      bool compact = false;
-      for (int i = 0; i < size_; i++) {
-        HCheckTableEntry* this_entry = &entries_[i];
-        HCheckTableEntry* that_entry;
-        if (this_entry->object_->IsPhi() &&
-            this_entry->object_->block() == succ) {
-          HPhi* phi = HPhi::cast(this_entry->object_);
-          HValue* phi_operand = phi->OperandAt(pred_index);
-          that_entry = that->Find(phi_operand);
-
-        } else {
-          that_entry = that->Find(this_entry->object_);
+                     HBasicBlock* that_block, Zone* zone) {
+    if (that_block->IsReachable()) {
+      if (that->size_ == 0) {
+        // If the other state is empty, simply reset.
+        size_ = 0;
+        cursor_ = 0;
+      } else {
+        bool compact = false;
+        for (int i = 0; i < size_; i++) {
+          HCheckTableEntry* this_entry = &entries_[i];
+          HCheckTableEntry* that_entry = that->Find(this_entry->object_);
+          if (that_entry == NULL) {
+            this_entry->object_ = NULL;
+            compact = true;
+          } else {
+            this_entry->maps_ =
+                this_entry->maps_->Union(that_entry->maps_, phase_->zone());
+            if (this_entry->check_ != that_entry->check_) {
+              this_entry->check_ = NULL;
+            }
+            ASSERT(this_entry->maps_->size() > 0);
+          }
         }
-
-        if (that_entry == NULL) {
-          this_entry->object_ = NULL;
-          compact = true;
-        } else {
-          this_entry->maps_ =
-              this_entry->maps_->Union(that_entry->maps_, phase_->zone());
-          this_entry->is_stable_ =
-              this_entry->is_stable_ && that_entry->is_stable_;
-          if (this_entry->check_ != that_entry->check_) {
-            this_entry->check_ = NULL;
-          }
-          ASSERT(this_entry->maps_->size() > 0);
-        }
+        if (compact) Compact();
       }
-      if (compact) Compact();
     }
-
     if (FLAG_trace_check_elimination) {
       PrintF("B%d checkmaps-table merged with B%d table:\n",
-             succ->block_id(), pred_block->block_id());
+             succ->block_id(), that_block->block_id());
       Print();
     }
     return this;
   }
 
   void ReduceCheckMaps(HCheckMaps* instr) {
     HValue* object = instr->value()->ActualValue();
     HCheckTableEntry* entry = Find(object);
     if (entry != NULL) {
       // entry found;
@@ skipping 10 matching lines @@
           TRACE(("Marking redundant CheckMaps #%d at B%d as dead\n",
               instr->id(), instr->block()->block_id()));
           // Mark check as dead but leave it in the graph as a checkpoint for
           // subsequent checks.
           instr->SetFlag(HValue::kIsDead);
           entry->check_ = instr;
           INC_STAT(removed_);
         }
         return;
       }
-      MapSet intersection = i->Intersect(a, phase_->zone());
-      if (intersection->size() == 0) {
+      i = i->Intersect(a, phase_->zone());
+      if (i->size() == 0) {
         // Intersection is empty; probably megamorphic, which is likely to
         // deopt anyway, so just leave things as they are.
         INC_STAT(empty_);
       } else {
-        // Update set of maps in the entry.
-        entry->maps_ = intersection;
-        if (intersection->size() != i->size()) {
-          // Narrow set of maps in the second check maps instruction.
-          HGraph* graph = instr->block()->graph();
-          if (entry->check_ != NULL &&
-              entry->check_->block() == instr->block() &&
-              entry->check_->IsCheckMaps()) {
-            // There is a check in the same block so replace it with a more
-            // strict check and eliminate the second check entirely.
-            HCheckMaps* check = HCheckMaps::cast(entry->check_);
-            TRACE(("CheckMaps #%d at B%d narrowed\n", check->id(),
-                check->block()->block_id()));
-            // Update map set and ensure that the check is alive.
-            check->set_map_set(intersection, graph->zone());
-            check->ClearFlag(HValue::kIsDead);
-            TRACE(("Replacing redundant CheckMaps #%d at B%d with #%d\n",
-                instr->id(), instr->block()->block_id(), entry->check_->id()));
-            instr->DeleteAndReplaceWith(entry->check_);
-          } else {
-            TRACE(("CheckMaps #%d at B%d narrowed\n", instr->id(),
-                instr->block()->block_id()));
-            instr->set_map_set(intersection, graph->zone());
-            entry->check_ = instr;
-          }
-
-          if (FLAG_trace_check_elimination) {
-            Print();
-          }
-          INC_STAT(narrowed_);
-        }
+        // TODO(titzer): replace the first check with a more strict check
+        INC_STAT(narrowed_);
       }
     } else {
       // No entry; insert a new one.
-      Insert(object, instr, instr->map_set().Copy(phase_->zone()),
-             instr->is_stable());
+      Insert(object, instr, instr->map_set().Copy(phase_->zone()));
     }
   }
 
   void ReduceCheckValue(HCheckValue* instr) {
     // Canonicalize HCheckValues; they might have their values load-eliminated.
     HValue* value = instr->Canonicalize();
     if (value == NULL) {
       instr->DeleteAndReplaceWith(instr->value());
       INC_STAT(removed_);
     } else if (value != instr) {
@@ skipping 16 matching lines @@
     instr->DeleteAndReplaceWith(constant);
     INC_STAT(loads_);
   }
 
   void ReduceCheckMapValue(HCheckMapValue* instr) {
     if (!instr->map()->IsConstant()) return;  // Nothing to learn.
 
     HValue* object = instr->value()->ActualValue();
     // Match a HCheckMapValue(object, HConstant(map))
     Unique<Map> map = MapConstant(instr->map());
-
-    HCheckTableEntry* entry = Find(object);
-    if (entry != NULL) {
-      MapSet maps = entry->maps_;
+    MapSet maps = FindMaps(object);
+    if (maps != NULL) {
       if (maps->Contains(map)) {
         if (maps->size() == 1) {
           // Object is known to have exactly this map.
-          if (entry->check_ != NULL) {
-            instr->DeleteAndReplaceWith(entry->check_);
-          } else {
-            // Mark check as dead but leave it in the graph as a checkpoint for
-            // subsequent checks.
-            instr->SetFlag(HValue::kIsDead);
-            entry->check_ = instr;
-          }
+          instr->DeleteAndReplaceWith(NULL);
           INC_STAT(removed_);
         } else {
           // Only one map survives the check.
           maps->Clear();
           maps->Add(map, phase_->zone());
-          entry->check_ = instr;
         }
       }
     } else {
       // No prior information.
-      // TODO(verwaest): Tag map constants with stability.
-      Insert(object, instr, map, false);
+      Insert(object, map);
     }
   }
 
   void ReduceCheckHeapObject(HCheckHeapObject* instr) {
     if (FindMaps(instr->value()->ActualValue()) != NULL) {
       // If the object has known maps, it's definitely a heap object.
       instr->DeleteAndReplaceWith(instr->value());
       INC_STAT(removed_cho_);
     }
   }
 
   void ReduceStoreNamedField(HStoreNamedField* instr) {
     HValue* object = instr->object()->ActualValue();
     if (instr->has_transition()) {
       // This store transitions the object to a new map.
       Kill(object);
-      Insert(object, NULL, MapConstant(instr->transition()),
-             instr->is_stable());
+      Insert(object, MapConstant(instr->transition()));
     } else if (IsMapAccess(instr->access())) {
       // This is a store directly to the map field of the object.
       Kill(object);
       if (!instr->value()->IsConstant()) return;
-      // TODO(verwaest): Tag with stability.
-      Insert(object, NULL, MapConstant(instr->value()), false);
+      Insert(object, MapConstant(instr->value()));
     } else {
       // If the instruction changes maps, it should be handled above.
-      CHECK(!instr->CheckChangesFlag(kMaps));
+      CHECK(!instr->CheckGVNFlag(kChangesMaps));
     }
   }
 
   void ReduceCompareMap(HCompareMap* instr) {
     MapSet maps = FindMaps(instr->value()->ActualValue());
     if (maps == NULL) return;
-
-    int succ;
     if (maps->Contains(instr->map())) {
-      if (maps->size() != 1) {
-        TRACE(("CompareMap #%d for #%d at B%d can't be eliminated: "
-               "ambiguous set of maps\n", instr->id(), instr->value()->id(),
-               instr->block()->block_id()));
-        return;
+      if (maps->size() == 1) {
+        TRACE(("Marking redundant CompareMap #%d at B%d as true\n",
+            instr->id(), instr->block()->block_id()));
+        instr->set_known_successor_index(0);
+        INC_STAT(compares_true_);
       }
-      succ = 0;
-      INC_STAT(compares_true_);
     } else {
-      succ = 1;
+      TRACE(("Marking redundant CompareMap #%d at B%d as false\n",
+          instr->id(), instr->block()->block_id()));
+      instr->set_known_successor_index(1);
       INC_STAT(compares_false_);
     }
-
-    TRACE(("Marking redundant CompareMap #%d for #%d at B%d as %s\n",
-        instr->id(), instr->value()->id(), instr->block()->block_id(),
-        succ == 0 ? "true" : "false"));
-    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.
     if (maps == NULL) return;
     if (maps->Contains(instr->original_map())) {
       // If the object has the original map, it will be transitioned.
       maps->Remove(instr->original_map());
       maps->Add(instr->transitioned_map(), phase_->zone());
     } else {
       // Object does not have the given map, thus the transition is redundant.
       instr->DeleteAndReplaceWith(instr->object());
       INC_STAT(transitions_);
     }
   }
 
-  // Reset the table.
-  void Reset() {
+  // Kill everything in the table.
+  void Kill() {
     size_ = 0;
     cursor_ = 0;
   }
 
-  // Kill everything in the table.
-  void KillUnstableEntries() {
-    bool compact = false;
-    for (int i = 0; i < size_; i++) {
-      HCheckTableEntry* entry = &entries_[i];
-      ASSERT(entry->object_ != NULL);
-      if (!entry->is_stable_) {
-        entry->object_ = NULL;
-        compact = true;
-      }
-    }
-    if (compact) Compact();
-  }
-
   // Kill everything in the table that may alias {object}.
   void Kill(HValue* object) {
     bool compact = false;
     for (int i = 0; i < size_; i++) {
       HCheckTableEntry* entry = &entries_[i];
       ASSERT(entry->object_ != NULL);
       if (phase_->aliasing_->MayAlias(entry->object_, object)) {
         entry->object_ = NULL;
         compact = true;
       }
@@ skipping 31 matching lines @@
       OS::MemMove(&entries_[R], &tmp_entries[0], L * sizeof(HCheckTableEntry));
     }
 
     cursor_ = size_;  // Move cursor to end.
   }
 
   void Print() {
     for (int i = 0; i < size_; i++) {
       HCheckTableEntry* entry = &entries_[i];
       ASSERT(entry->object_ != NULL);
-      PrintF("  checkmaps-table @%d: %s #%d ", i,
-             entry->object_->IsPhi() ? "phi" : "object", entry->object_->id());
+      PrintF("  checkmaps-table @%d: object #%d ", i, entry->object_->id());
       if (entry->check_ != NULL) {
         PrintF("check #%d ", entry->check_->id());
       }
       MapSet list = entry->maps_;
       PrintF("%d maps { ", list->size());
       for (int j = 0; j < list->size(); j++) {
         if (j > 0) PrintF(", ");
         PrintF("%" V8PRIxPTR, list->at(j).Hashcode());
       }
       PrintF(" }\n");
     }
   }
 
+ private:
   HCheckTableEntry* Find(HValue* object) {
     for (int i = size_ - 1; i >= 0; i--) {
       // Search from most-recently-inserted to least-recently-inserted.
       HCheckTableEntry* entry = &entries_[i];
       ASSERT(entry->object_ != NULL);
       if (phase_->aliasing_->MustAlias(entry->object_, object)) return entry;
     }
     return NULL;
   }
 
   MapSet FindMaps(HValue* object) {
     HCheckTableEntry* entry = Find(object);
     return entry == NULL ? NULL : entry->maps_;
   }
 
-  void Insert(HValue* object,
-              HInstruction* check,
-              Unique<Map> map,
-              bool is_stable) {
+  void Insert(HValue* object, Unique<Map> map) {
     MapSet list = new(phase_->zone()) UniqueSet<Map>();
     list->Add(map, phase_->zone());
-    Insert(object, check, list, is_stable);
+    Insert(object, NULL, list);
   }
 
-  void Insert(HValue* object,
-              HInstruction* check,
-              MapSet maps,
-              bool is_stable) {
+  void Insert(HValue* object, HCheckMaps* check, MapSet maps) {
     HCheckTableEntry* entry = &entries_[cursor_++];
     entry->object_ = object;
     entry->check_ = check;
     entry->maps_ = maps;
-    entry->is_stable_ = is_stable;
     // If the table becomes full, wrap around and overwrite older entries.
     if (cursor_ == kMaxTrackedObjects) cursor_ = 0;
     if (size_ < kMaxTrackedObjects) size_++;
   }
 
   bool IsMapAccess(HObjectAccess access) {
     return access.IsInobject() && access.offset() == JSObject::kMapOffset;
   }
 
   Unique<Map> MapConstant(HValue* value) {
     return Unique<Map>::cast(HConstant::cast(value)->GetUnique());
   }
 
   friend class HCheckMapsEffects;
-  friend class HCheckEliminationPhase;
 
   HCheckEliminationPhase* phase_;
   HCheckTableEntry entries_[kMaxTrackedObjects];
   int16_t cursor_;  // Must be <= kMaxTrackedObjects
   int16_t size_;    // Must be <= kMaxTrackedObjects
   // TODO(titzer): STATIC_ASSERT kMaxTrackedObjects < max(cursor_)
 };
 
 
 // Collects instructions that can cause effects that invalidate information
 // needed for check elimination.
 class HCheckMapsEffects : public ZoneObject {
  public:
   explicit HCheckMapsEffects(Zone* zone)
-    : stores_(5, zone) { }
+    : maps_stored_(false),
+      stores_(5, zone) { }
 
   inline bool Disabled() {
     return false;  // Effects are _not_ disabled.
   }
 
   // Process a possibly side-effecting instruction.
   void Process(HInstruction* instr, Zone* zone) {
-    if (instr->IsStoreNamedField()) {
-      stores_.Add(HStoreNamedField::cast(instr), zone);
-    } else {
-      flags_.Add(instr->ChangesFlags());
+    switch (instr->opcode()) {
+      case HValue::kStoreNamedField: {
+        stores_.Add(HStoreNamedField::cast(instr), zone);
+        break;
+      }
+      case HValue::kOsrEntry: {
+        // Kill everything. Loads must not be hoisted past the OSR entry.
+        maps_stored_ = true;
+      }
+      default: {
+        maps_stored_ |= (instr->CheckGVNFlag(kChangesMaps) |
+                         instr->CheckGVNFlag(kChangesElementsKind));
+      }
     }
   }
 
   // Apply these effects to the given check elimination table.
   void Apply(HCheckTable* table) {
-    if (flags_.Contains(kOsrEntries)) {
-      table->Reset();
-      return;
-    }
-    if (flags_.Contains(kMaps) || flags_.Contains(kElementsKind)) {
+    if (maps_stored_) {
       // Uncontrollable map modifications; kill everything.
-      table->KillUnstableEntries();
+      table->Kill();
       return;
     }
 
     // Kill maps for each store contained in these effects.
     for (int i = 0; i < stores_.length(); i++) {
       HStoreNamedField* s = stores_[i];
       if (table->IsMapAccess(s->access()) || s->has_transition()) {
         table->Kill(s->object()->ActualValue());
       }
     }
   }
 
   // Union these effects with the other effects.
   void Union(HCheckMapsEffects* that, Zone* zone) {
-    flags_.Add(that->flags_);
+    maps_stored_ |= that->maps_stored_;
     for (int i = 0; i < that->stores_.length(); i++) {
       stores_.Add(that->stores_[i], zone);
     }
   }
 
  private:
-  GVNFlagSet flags_;
+  bool maps_stored_ : 1;
   ZoneList<HStoreNamedField*> stores_;
 };
 
 
 // The main routine of the analysis phase. Use the HFlowEngine for either a
 // local or a global analysis.
 void HCheckEliminationPhase::Run() {
   HFlowEngine<HCheckTable, HCheckMapsEffects> engine(graph(), zone());
   HCheckTable* table = new(zone()) HCheckTable(this);
 
   if (GLOBAL) {
     // Perform a global analysis.
     engine.AnalyzeDominatedBlocks(graph()->blocks()->at(0), table);
   } else {
     // Perform only local analysis.
     for (int i = 0; i < graph()->blocks()->length(); i++) {
-      table->Reset();
+      table->Kill();
       engine.AnalyzeOneBlock(graph()->blocks()->at(i), table);
     }
   }
 
   if (FLAG_trace_check_elimination) PrintStats();
 }
 
 
 // Are we eliminated yet?
 void HCheckEliminationPhase::PrintStats() {
 #if DEBUG
   #define PRINT_STAT(x) if (x##_ > 0) PrintF(" %-16s = %2d\n", #x, x##_)
 #else
   #define PRINT_STAT(x)
 #endif
   PRINT_STAT(redundant);
   PRINT_STAT(removed);
   PRINT_STAT(removed_cho);
   PRINT_STAT(narrowed);
   PRINT_STAT(loads);
   PRINT_STAT(empty);
   PRINT_STAT(compares_true);
   PRINT_STAT(compares_false);
   PRINT_STAT(transitions);
 }
 
 } }  // namespace v8::internal