Also eliminate map checks with transitions.

R=ulan@chromium.org

Review URL: https://chromiumcodereview.appspot.com/19888006

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15821 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/hydrogen-instructions.cc

@@ -2791,6 +2791,39 @@ HCheckMaps* HCheckMaps::New(HValue* value,
 }
 
 
+HCheckMaps* HCheckMaps::NewWithTransitions(HValue* value,
+                                           Handle<Map> map,
+                                           Zone* zone,
+                                           CompilationInfo* info) {
+  HCheckMaps* check_map = new(zone) HCheckMaps(value, zone, value);
+  check_map->map_set_.Add(map, zone);
+
+  // Since transitioned elements maps of the initial map don't fail the map
+  // check, the CheckMaps instruction doesn't need to depend on ElementsKinds.
+  check_map->ClearGVNFlag(kDependsOnElementsKind);
+
+  ElementsKind kind = map->elements_kind();
+  bool packed = IsFastPackedElementsKind(kind);
+  while (CanTransitionToMoreGeneralFastElementsKind(kind, packed)) {
+    kind = GetNextMoreGeneralFastElementsKind(kind, packed);
+    Map* transitioned_map =
+        map->LookupElementsTransitionMap(kind);
+    if (transitioned_map) {
+      check_map->map_set_.Add(Handle<Map>(transitioned_map), zone);
+    }
+  };
+
+  if (map->CanOmitMapChecks() &&
+      value->IsConstant() &&
+      HConstant::cast(value)->InstanceOf(map)) {
+    check_map->omit(info);
+  }
+
+  check_map->map_set_.Sort();
+  return check_map;
+}
+
+
 void HCheckMaps::FinalizeUniqueValueId() {
   if (!map_unique_ids_.is_empty()) return;
   Zone* zone = block()->zone();

src/hydrogen-instructions.h

@@ -2750,27 +2750,7 @@ class HCheckMaps: public HTemplateInstruction<2> {
   }
 
   static HCheckMaps* NewWithTransitions(HValue* value, Handle<Map> map,
-                                        Zone* zone) {
-    HCheckMaps* check_map = new(zone) HCheckMaps(value, zone, value);
-    check_map->map_set_.Add(map, zone);
-
-    // Since transitioned elements maps of the initial map don't fail the map
-    // check, the CheckMaps instruction doesn't need to depend on ElementsKinds.
-    check_map->ClearGVNFlag(kDependsOnElementsKind);
-
-    ElementsKind kind = map->elements_kind();
-    bool packed = IsFastPackedElementsKind(kind);
-    while (CanTransitionToMoreGeneralFastElementsKind(kind, packed)) {
-      kind = GetNextMoreGeneralFastElementsKind(kind, packed);
-      Map* transitioned_map =
-          map->LookupElementsTransitionMap(kind);
-      if (transitioned_map) {
-        check_map->map_set_.Add(Handle<Map>(transitioned_map), zone);
-      }
-    };
-    check_map->map_set_.Sort();
-    return check_map;
-  }
+                                        Zone* zone, CompilationInfo* info);
 
   bool CanOmitMapChecks() { return omit_; }
 

src/hydrogen.cc

@@ -4549,7 +4549,8 @@ void HOptimizedGraphBuilder::AddCheckMap(HValue* object, Handle<Map> map) {
 void HOptimizedGraphBuilder::AddCheckMapsWithTransitions(HValue* object,
                                                          Handle<Map> map) {
   BuildCheckHeapObject(object);
-  AddInstruction(HCheckMaps::NewWithTransitions(object, map, zone()));
+  AddInstruction(HCheckMaps::NewWithTransitions(
+      object, map, zone(), top_info()));
 }
 
 

test/mjsunit/omit-constant-mapcheck.js

@@ -53,3 +53,18 @@ assertEquals(2, load2());
 g2.b = 10;
 g2.a = 5;
 assertEquals(5, load2());
+
+var g3 = { a:2, b:9, c:1 }
+
+function store(v) {
+  g3.a = v;
+  return g3.a;
+}
+
+assertEquals(5, store(5));
+assertEquals(8, store(8));
+%OptimizeFunctionOnNextCall(store);
+assertEquals(10, store(10));
+delete g3.c;
+store(7);
+assertEquals({a:7, b:9}, g3);