Eliminate map checks of constant values.

src/hydrogen-instructions.cc

 // Copyright 2012 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 1662 matching lines @@
   }
 }
 
 
 void HCheckMaps::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" [%p", *map_set()->first());
   for (int i = 1; i < map_set()->length(); ++i) {
     stream->Add(",%p", *map_set()->at(i));
   }
-  stream->Add("]");
+  stream->Add("]%s", CanOmitMapChecks() ? "(omitted)" : "");
 }
 
 
 void HCheckFunction::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" %p", *target());
 }
 
 
 HValue* HCheckFunction::Canonicalize() {
@@ skipping 1056 matching lines @@
     // We don't have an easy way to handle both a call (to the generic stub) and
     // a deopt in the same hydrogen instruction, so in this case we don't add
     // the negative lookups which can deopt - just let the generic stub handle
     // them.
     SetAllSideEffects();
     need_generic_ = true;
   }
 }
 
 
+HCheckMaps* HCheckMaps::New(HValue* value,
+                            Handle<Map> map,
+                            Zone* zone,
+                            CompilationInfo* info,
+                            HValue* typecheck) {
+  HCheckMaps* check_map = new(zone) HCheckMaps(value, zone, typecheck);
+  check_map->map_set_.Add(map, zone);
+  if (map->CanOmitMapChecks() &&
+      value->IsConstant() &&
+      HConstant::cast(value)->InstanceOf(map)) {
+    check_map->omit(info);
+  }
+  return check_map;
+}
+
+
 void HCheckMaps::FinalizeUniqueValueId() {
   if (!map_unique_ids_.is_empty()) return;
   Zone* zone = block()->zone();
   map_unique_ids_.Initialize(map_set_.length(), zone);
   for (int i = 0; i < map_set_.length(); i++) {
     map_unique_ids_.Add(UniqueValueId(map_set_.at(i)), zone);
   }
 }
 
 
@@ skipping 1210 matching lines @@
     case kBackingStore:
       if (!name_.is_null()) stream->Add(*String::cast(*name_)->ToCString());
       stream->Add("[backing-store]");
       break;
   }
 
   stream->Add("@%d", offset());
 }
 
 } }  // namespace v8::internal