Revert "[turbofan] Instance type tracking in load elimination."

This reverts commit ddd15cda.

Reason for revert: Blocks roll: https://chromium-review.googlesource.com/c/chromium/src/+/732565

Original change's description:
> [turbofan] Instance type tracking in load elimination.
> 
> This tracks instance type in load elimination, so that it can be used
> to prune control flow with unreachable states.
> 
> (This is a cut down version of https://chromium-review.googlesource.com/c/v8/v8/+/727761),
> the regression should be addressed by the map invalidation fix from
> https://chromium-review.googlesource.com/c/v8/v8/+/730705.)
> 
> Bug: v8:6396
> Change-Id: I3acab16ebbc0f1f16c7900a8d307deb84e1cb618
> Reviewed-on: https://chromium-review.googlesource.com/732307
> Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
> Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
> Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48812}

TBR=jarin@chromium.org,bmeurer@chromium.org

Change-Id: I1a3fe1d62c05889ea83e2f6cfb31a6ccbe65241d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6396
Reviewed-on: https://chromium-review.googlesource.com/732898Reviewed-by: Michael Hablich <hablich@chromium.org>
Commit-Queue: Michael Hablich <hablich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48833}

src/compiler/load-elimination.h

@@ -24,7 +24,6 @@ class CommonOperatorBuilder;
 struct FieldAccess;
 class Graph;
 class JSGraph;
-class MapsParameterInfo;
 
 class V8_EXPORT_PRIVATE LoadElimination final
     : public NON_EXPORTED_BASE(AdvancedReducer) {
@@ -197,64 +196,27 @@ class V8_EXPORT_PRIVATE LoadElimination final
   static MapSetComparisonResult CompareMapSets(ZoneHandleSet<Map> const& lhs,
                                                ZoneHandleSet<Map> const& rhs);
 
-  class AbstractMapInfo {
-   public:
-    enum InfoValid { kMapsValid = 1 << 0, kInstanceTypeValid = 1 << 1 };
-    typedef base::Flags<InfoValid, uint8_t> Validity;
-
-    AbstractMapInfo();
-    explicit AbstractMapInfo(ZoneHandleSet<Map> const& maps);
-    explicit AbstractMapInfo(InstanceType instance_type);
-    explicit AbstractMapInfo(MapsParameterInfo const& info);
-
-    bool operator==(AbstractMapInfo const& other) const;
-    bool operator!=(AbstractMapInfo const& other) const;
-
-    ZoneHandleSet<Map> const& maps() const;
-    InstanceType instance_type() const;
-
-    bool maps_valid() const { return info_validity_ & kMapsValid; }
-    bool instance_type_valid() const {
-      return info_validity_ & kInstanceTypeValid;
-    }
-    bool empty() const { return info_validity_ == 0; }
-
-    AbstractMapInfo Merge(AbstractMapInfo const& other) const;
-
-    MapSetComparisonResult Compare(AbstractMapInfo const& other) const;
-
-   private:
-    AbstractMapInfo(ZoneHandleSet<Map> const& maps, InstanceType instance_type,
-                    Validity validity);
-
-    ZoneHandleSet<Map> maps_;
-    InstanceType instance_type_;
-    Validity info_validity_;
-  };
-
   // Abstract state to approximate the current map of an object along the
   // effect paths through the graph.
   class AbstractMaps final : public ZoneObject {
    public:
     explicit AbstractMaps(Zone* zone);
-    AbstractMaps(Node* object, AbstractMapInfo const& map_info, Zone* zone);
+    AbstractMaps(Node* object, ZoneHandleSet<Map> maps, Zone* zone);
 
-    AbstractMaps const* Extend(Node* object, AbstractMapInfo const& maps,
+    AbstractMaps const* Extend(Node* object, ZoneHandleSet<Map> maps,
                                Zone* zone) const;
     bool Lookup(Node* object, ZoneHandleSet<Map>* object_maps) const;
-    bool Lookup(Node* object, AbstractMapInfo* maps_info) const;
     AbstractMaps const* Kill(const AliasStateInfo& alias_info,
                              Zone* zone) const;
     bool Equals(AbstractMaps const* that) const {
       return this == that || this->info_for_node_ == that->info_for_node_;
     }
     AbstractMaps const* Merge(AbstractMaps const* that, Zone* zone) const;
-    AbstractMaps const* KillMutableState(Zone* zone) const;
 
     void Print() const;
 
    private:
-    ZoneMap<Node*, AbstractMapInfo> info_for_node_;
+    ZoneMap<Node*, ZoneHandleSet<Map>> info_for_node_;
   };
 
   class AbstractState final : public ZoneObject {
@@ -264,13 +226,10 @@ class V8_EXPORT_PRIVATE LoadElimination final
 
     AbstractState const* SetMaps(Node* object, ZoneHandleSet<Map> maps,
                                  Zone* zone) const;
-    AbstractState const* SetMaps(Node* object, AbstractMapInfo const& map_info,
-                                 Zone* zone) const;
     AbstractState const* KillMaps(Node* object, Zone* zone) const;
     AbstractState const* KillMaps(const AliasStateInfo& alias_info,
                                   Zone* zone) const;
     bool LookupMaps(Node* object, ZoneHandleSet<Map>* object_maps) const;
-    bool LookupMaps(Node* object, AbstractMapInfo* map_info) const;
 
     AbstractState const* AddField(Node* object, size_t index, Node* value,
                                   MaybeHandle<Name> name, Zone* zone) const;
@@ -294,8 +253,6 @@ class V8_EXPORT_PRIVATE LoadElimination final
     AbstractState const* AddCheck(Node* node, Zone* zone) const;
     Node* LookupCheck(Node* node) const;
 
-    AbstractState const* KillMutableState(Zone* zone) const;
-
     bool is_unreachable() const { return is_unreachable_; }
 
     void Print() const;