Optimize the equality check case of ICCompare stubs.

src/ic.cc

Index: src/ic.cc
===================================================================
--- src/ic.cc	(revision 9957)
+++ src/ic.cc	(working copy)
@@ -2315,6 +2315,7 @@
     case SMIS: return "SMIS";
     case HEAP_NUMBERS: return "HEAP_NUMBERS";
     case OBJECTS: return "OBJECTS";
+    case KNOWN_OBJECTS: return "OBJECTS";
     case SYMBOLS: return "SYMBOLS";
     case STRINGS: return "STRINGS";
     case GENERIC: return "GENERIC";
@@ -2329,20 +2330,37 @@
                                         bool has_inlined_smi_code,
                                         Handle<Object> x,
                                         Handle<Object> y) {
-  if (!has_inlined_smi_code && state != UNINITIALIZED && state != SYMBOLS) {
-    return GENERIC;
+  switch (state) {
+    case UNINITIALIZED:
+      if (x->IsSmi() && y->IsSmi()) return SMIS;
+      if (x->IsNumber() && y->IsNumber()) return HEAP_NUMBERS;
+      if (!Token::IsEqualityOp(op_)) return GENERIC;
+      if (x->IsSymbol() && y->IsSymbol()) return SYMBOLS;
+      if (x->IsString() && y->IsString()) return STRINGS;
+      if (x->IsJSObject() && y->IsJSObject()) {
+        if (Handle<JSObject>::cast(x)->map() ==
+            Handle<JSObject>::cast(y)->map() &&
+            Token::IsEqualityOp(op_)) {
+          return KNOWN_OBJECTS;
+        } else {
+          return OBJECTS;
+        }
+      }
+      return GENERIC;
+    case SMIS:
+      return has_inlined_smi_code && x->IsNumber() && y->IsNumber()
+          ? HEAP_NUMBERS
+          : GENERIC;
+    case SYMBOLS:
+      ASSERT(Token::IsEqualityOp(op_));
+      return x->IsString() && y->IsString() ? STRINGS : GENERIC;
+    case HEAP_NUMBERS:
+    case STRINGS:
+    case OBJECTS:
+    case KNOWN_OBJECTS:
+    case GENERIC:
+      return GENERIC;
   }
-  if (state == UNINITIALIZED && x->IsSmi() && y->IsSmi()) return SMIS;
-  if ((state == UNINITIALIZED || (state == SMIS && has_inlined_smi_code)) &&
-      x->IsNumber() && y->IsNumber()) return HEAP_NUMBERS;
-  if (op_ != Token::EQ && op_ != Token::EQ_STRICT) return GENERIC;
-  if (state == UNINITIALIZED &&
-      x->IsSymbol() && y->IsSymbol()) return SYMBOLS;
-  if ((state == UNINITIALIZED || state == SYMBOLS) &&
-      x->IsString() && y->IsString()) return STRINGS;
-  if (state == UNINITIALIZED &&
-      x->IsJSObject() && y->IsJSObject()) return OBJECTS;
-  return GENERIC;
 }