[crankshaft] Remove adventurous operator< for Handle<Map>.

This operator< overload is rather dangerous for handles. And we don't
actually need a std::set in the chunk builder, since duplicates are
automatically eliminated later when the code dependencies are committed.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1214573004

Cr-Commit-Position: refs/heads/master@{#29401}

src/handles.h

@@ -174,13 +174,6 @@ inline Handle<T> handle(T* t) {
 }
 
 
-// Key comparison function for Map handles.
-inline bool operator<(const Handle<Map>& lhs, const Handle<Map>& rhs) {
-  // This is safe because maps don't move.
-  return *lhs < *rhs;
-}
-
-
 class DeferredHandles;
 class HandleScopeImplementer;
 

src/lithium.cc

@@ -273,8 +273,8 @@ LChunk::LChunk(CompilationInfo* info, HGraph* graph)
       instructions_(32, info->zone()),
       pointer_maps_(8, info->zone()),
       inlined_functions_(1, info->zone()),
-      deprecation_dependencies_(MapLess(), MapAllocator(info->zone())),
-      stability_dependencies_(MapLess(), MapAllocator(info->zone())) {}
+      deprecation_dependencies_(32, info->zone()),
+      stability_dependencies_(8, info->zone()) {}
 
 
 LLabel* LChunk::GetLabel(int block_id) const {
@@ -464,17 +464,13 @@ void LChunk::CommitDependencies(Handle<Code> code) const {
   if (!code->is_optimized_code()) return;
   HandleScope scope(isolate());
 
-  for (MapSet::const_iterator it = deprecation_dependencies_.begin(),
-       iend = deprecation_dependencies_.end(); it != iend; ++it) {
-    Handle<Map> map = *it;
+  for (Handle<Map> map : deprecation_dependencies_) {
     DCHECK(!map->is_deprecated());
     DCHECK(map->CanBeDeprecated());
     Map::AddDependentCode(map, DependentCode::kTransitionGroup, code);
   }
 
-  for (MapSet::const_iterator it = stability_dependencies_.begin(),
-       iend = stability_dependencies_.end(); it != iend; ++it) {
-    Handle<Map> map = *it;
+  for (Handle<Map> map : stability_dependencies_) {
     DCHECK(map->is_stable());
     DCHECK(map->CanTransition());
     Map::AddDependentCode(map, DependentCode::kPrototypeCheckGroup, code);

src/lithium.h

@@ -665,14 +665,14 @@ class LChunk : public ZoneObject {
     DCHECK(!map->is_deprecated());
     if (!map->CanBeDeprecated()) return;
     DCHECK(!info_->IsStub());
-    deprecation_dependencies_.insert(map);
+    deprecation_dependencies_.Add(map, zone());
   }
 
   void AddStabilityDependency(Handle<Map> map) {
     DCHECK(map->is_stable());
     if (!map->CanTransition()) return;
     DCHECK(!info_->IsStub());
-    stability_dependencies_.insert(map);
+    stability_dependencies_.Add(map, zone());
   }
 
   Zone* zone() const { return info_->zone(); }
@@ -690,10 +690,6 @@ class LChunk : public ZoneObject {
   int spill_slot_count_;
 
  private:
-  typedef std::less<Handle<Map> > MapLess;
-  typedef zone_allocator<Handle<Map> > MapAllocator;
-  typedef std::set<Handle<Map>, MapLess, MapAllocator> MapSet;
-
   void RegisterWeakObjectsInOptimizedCode(Handle<Code> code) const;
   void CommitDependencies(Handle<Code> code) const;
 
@@ -703,8 +699,8 @@ class LChunk : public ZoneObject {
   ZoneList<LInstruction*> instructions_;
   ZoneList<LPointerMap*> pointer_maps_;
   ZoneList<Handle<SharedFunctionInfo>> inlined_functions_;
-  MapSet deprecation_dependencies_;
-  MapSet stability_dependencies_;
+  ZoneList<Handle<Map>> deprecation_dependencies_;
+  ZoneList<Handle<Map>> stability_dependencies_;
 };