Optimize the equality check case of ICCompare stubs.

src/hydrogen.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
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@@ skipping 5979 matching lines @@
       result->set_position(expr->position());
       return ast_context()->ReturnInstruction(result, expr->id());
     }
   } else if (op == Token::IN) {
     HIn* result = new(zone()) HIn(context, left, right);
     result->set_position(expr->position());
     return ast_context()->ReturnInstruction(result, expr->id());
   } else if (type_info.IsNonPrimitive()) {
     switch (op) {
       case Token::EQ:
       case Token::EQ_STRICT: {

[Kevin Millikin (Chromium), 2011/11/10 19:08:42]

I guess if EQ_STRICT, then we'll never have a compare map (because we don't go
to KNOWN_OBJECTS in that case).  I wonder if we should?

[Rico, 2011/11/11 08:49:11]

Of course we should, nice catch.

-        AddInstruction(new(zone()) HCheckNonSmi(left));
-        AddInstruction(HCheckInstanceType::NewIsSpecObject(left));
-        AddInstruction(new(zone()) HCheckNonSmi(right));
-        AddInstruction(HCheckInstanceType::NewIsSpecObject(right));
-        HCompareObjectEqAndBranch* result =
-            new(zone()) HCompareObjectEqAndBranch(left, right);
-        result->set_position(expr->position());
-        return ast_context()->ReturnControl(result, expr->id());
+        // Can we get away with map check and not instance type check?
+        Handle<Map> map = oracle()->GetCompareMap(expr);
+        if (!map.is_null()) {
+          AddInstruction(new(zone()) HCheckNonSmi(left));
+          AddInstruction(new(zone()) HCheckMap(left, map));
+          AddInstruction(new(zone()) HCheckNonSmi(right));
+          AddInstruction(new(zone()) HCheckMap(right, map));
+          HCompareObjectEqAndBranch* result =
+              new(zone()) HCompareObjectEqAndBranch(left, right);
+          result->set_position(expr->position());
+          return ast_context()->ReturnControl(result, expr->id());
+        } else {
+          AddInstruction(new(zone()) HCheckNonSmi(left));
+          AddInstruction(HCheckInstanceType::NewIsSpecObject(left));
+          AddInstruction(new(zone()) HCheckNonSmi(right));
+          AddInstruction(HCheckInstanceType::NewIsSpecObject(right));
+          HCompareObjectEqAndBranch* result =
+              new(zone()) HCompareObjectEqAndBranch(left, right);
+          result->set_position(expr->position());
+          return ast_context()->ReturnControl(result, expr->id());
+        }
       }
       default:
         return Bailout("Unsupported non-primitive compare");
     }
   } else if (type_info.IsString() && oracle()->IsSymbolCompare(expr) &&
              (op == Token::EQ || op == Token::EQ_STRICT)) {
     AddInstruction(new(zone()) HCheckNonSmi(left));
     AddInstruction(HCheckInstanceType::NewIsSymbol(left));
     AddInstruction(new(zone()) HCheckNonSmi(right));
     AddInstruction(HCheckInstanceType::NewIsSymbol(right));
@@ skipping 1075 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal