Revert "Handle HCheckInstanceType and HIsStringAndBranch in check elimination."

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 d9713813c843be1a5a9b1ad489fcd30c8242062b..506a04588995fbd25c858424b1461adf1155b781 100644
--- a/src/hydrogen-check-elimination.cc
+++ b/src/hydrogen-check-elimination.cc
@@ -104,10 +104,6 @@ class HCheckTable : public ZoneObject {
         ReduceCompareObjectEqAndBranch(HCompareObjectEqAndBranch::cast(instr));
         break;
       }
-      case HValue::kIsStringAndBranch: {
-        ReduceIsStringAndBranch(HIsStringAndBranch::cast(instr));
-        break;
-      }
       case HValue::kTransitionElementsKind: {
         ReduceTransitionElementsKind(
             HTransitionElementsKind::cast(instr));
@@ -117,10 +113,6 @@ class HCheckTable : public ZoneObject {
         ReduceCheckHeapObject(HCheckHeapObject::cast(instr));
         break;
       }
-      case HValue::kCheckInstanceType: {
-        ReduceCheckInstanceType(HCheckInstanceType::cast(instr));
-        break;
-      }
       default: {
         // If the instruction changes maps uncontrollably, drop everything.
         if (instr->CheckChangesFlag(kOsrEntries)) {
@@ -133,7 +125,7 @@ class HCheckTable : public ZoneObject {
         }
       }
       // Improvements possible:
-      // - eliminate redundant HCheckSmi instructions
+      // - eliminate redundant HCheckSmi, HCheckInstanceType instructions
       // - track which values have been HCheckHeapObject'd
     }
 
@@ -269,28 +261,6 @@ class HCheckTable : public ZoneObject {
           ASSERT_NE(HCheckTableEntry::UNCHECKED_STABLE, re->state_);
         }
         learned = true;
-      } else if (end->IsIsStringAndBranch()) {
-        HIsStringAndBranch* cmp = HIsStringAndBranch::cast(end);
-        HValue* object = cmp->value()->ActualValue();
-        HCheckTableEntry* entry = copy->Find(object);
-        if (is_true_branch) {
-          // Learn on the true branch of if(IsString(x)).
-          if (entry == NULL) {
-            copy->Insert(object, NULL, string_maps(),
-                         HCheckTableEntry::CHECKED);
-          } else {
-            EnsureChecked(entry, object, cmp);
-            entry->maps_ = entry->maps_->Intersect(string_maps(), zone);
-            ASSERT_NE(HCheckTableEntry::UNCHECKED_STABLE, entry->state_);
-          }
-        } else {
-          // Learn on the false branch of if(IsString(x)).
-          if (entry != NULL) {
-            EnsureChecked(entry, object, cmp);
-            entry->maps_ = entry->maps_->Subtract(string_maps(), zone);
-            ASSERT_NE(HCheckTableEntry::UNCHECKED_STABLE, entry->state_);
-          }
-        }
       }
       // Learning on false branches requires storing negative facts.
     }
@@ -445,50 +415,6 @@ class HCheckTable : public ZoneObject {
     }
   }
 
-  void ReduceCheckInstanceType(HCheckInstanceType* instr) {
-    HValue* value = instr->value()->ActualValue();
-    HCheckTableEntry* entry = Find(value);
-    if (entry == NULL) {
-      if (instr->check() == HCheckInstanceType::IS_STRING) {
-        Insert(value, NULL, string_maps(), HCheckTableEntry::CHECKED);
-      }
-      return;
-    }
-    UniqueSet<Map>* maps = new(zone()) UniqueSet<Map>(
-        entry->maps_->size(), zone());
-    for (int i = 0; i < entry->maps_->size(); ++i) {
-      InstanceType type;
-      Unique<Map> map = entry->maps_->at(i);
-      {
-        // This is safe, because maps don't move and their instance type does
-        // not change.
-        AllowHandleDereference allow_deref;
-        type = map.handle()->instance_type();
-      }
-      if (instr->is_interval_check()) {
-        InstanceType first_type, last_type;
-        instr->GetCheckInterval(&first_type, &last_type);
-        if (first_type <= type && type <= last_type) maps->Add(map, zone());
-      } else {
-        uint8_t mask, tag;
-        instr->GetCheckMaskAndTag(&mask, &tag);
-        if ((type & mask) == tag) maps->Add(map, zone());
-      }
-    }
-    if (maps->size() == entry->maps_->size()) {
-      TRACE(("Removing redundant CheckInstanceType #%d at B%d\n",
-              instr->id(), instr->block()->block_id()));
-      EnsureChecked(entry, value, instr);
-      instr->DeleteAndReplaceWith(value);
-      INC_STAT(removed_cit_);
-    } else if (maps->size() != 0) {
-      entry->maps_ = maps;
-      if (entry->state_ == HCheckTableEntry::UNCHECKED_STABLE) {
-        entry->state_ = HCheckTableEntry::CHECKED_STABLE;
-      }
-    }
-  }
-
   void ReduceLoadNamedField(HLoadNamedField* instr) {
     // Reduce a load of the map field when it is known to be a constant.
     if (!instr->access().IsMap()) {
@@ -602,28 +528,6 @@ class HCheckTable : public ZoneObject {
     instr->block()->MarkSuccEdgeUnreachable(unreachable_succ);
   }
 
-  void ReduceIsStringAndBranch(HIsStringAndBranch* instr) {
-    HValue* value = instr->value()->ActualValue();
-    HCheckTableEntry* entry = Find(value);
-    if (entry == NULL) return;
-    EnsureChecked(entry, value, instr);
-    int succ;
-    if (entry->maps_->IsSubset(string_maps())) {
-      TRACE(("Marking redundant IsStringAndBranch #%d at B%d as true\n",
-             instr->id(), instr->block()->block_id()));
-      succ = 0;
-    } else {
-      MapSet intersection = entry->maps_->Intersect(string_maps(), zone());
-      if (intersection->size() > 0) return;
-      TRACE(("Marking redundant IsStringAndBranch #%d at B%d as false\n",
-            instr->id(), instr->block()->block_id()));
-      succ = 1;
-    }
-    instr->set_known_successor_index(succ);
-    int unreachable_succ = 1 - succ;
-    instr->block()->MarkSuccEdgeUnreachable(unreachable_succ);
-  }
-
   void ReduceTransitionElementsKind(HTransitionElementsKind* instr) {
     HValue* object = instr->object()->ActualValue();
     HCheckTableEntry* entry = Find(object);
@@ -784,7 +688,6 @@ class HCheckTable : public ZoneObject {
   }
 
   Zone* zone() const { return phase_->zone(); }
-  MapSet string_maps() const { return phase_->string_maps(); }
 
   friend class HCheckMapsEffects;
   friend class HCheckEliminationPhase;
@@ -891,7 +794,6 @@ void HCheckEliminationPhase::PrintStats() {
   PRINT_STAT(redundant);
   PRINT_STAT(removed);
   PRINT_STAT(removed_cho);
-  PRINT_STAT(removed_cit);
   PRINT_STAT(narrowed);
   PRINT_STAT(loads);
   PRINT_STAT(empty);