Create specialized code stubs for PixelArray loads.

src/runtime.cc

 // Copyright 2010 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:
 //
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@@ skipping 3473 matching lines @@
         value = JSGlobalPropertyCell::cast(value)->value();
         if (!value->IsTheHole()) return value;
         // If value is the hole do the general lookup.
       }
     }
   } else if (args[0]->IsString() && args[1]->IsSmi()) {
     // Fast case for string indexing using [] with a smi index.
     HandleScope scope;
     Handle<String> str = args.at<String>(0);
     int index = Smi::cast(args[1])->value();
-    Handle<Object> result = GetCharAt(str, index);
-    return *result;
+    if (index >= 0 && index < str->length()) {

[Mads Ager (chromium), 2011/02/01 12:02:12]

Good catch! Thanks!

[Søren Thygesen Gjesse, 2011/02/01 12:02:56]

Is this a bug-fix? If so maybe there should be a regression test.

[danno, 2011/02/03 12:53:26]

There's actually an existing test case that wasn't quite sufficient to cause
this problem to show up in debug mode (although it did in release!) since it
didn't call a function a sufficient number of times to cause all of the map IC
transitions to land in the generic keyed load IC: regress-900966.js. I augmented
the test case to make sure it covers all of the transitions.

+      Handle<Object> result = GetCharAt(str, index);
+      return *result;
+    }
   }
 
   // Fall back to GetObjectProperty.
   return Runtime::GetObjectProperty(args.at<Object>(0),
                                     args.at<Object>(1));
 }
 
 
 static MaybeObject* Runtime_DefineOrRedefineAccessorProperty(Arguments args) {
   ASSERT(args.length() == 5);
@@ skipping 7368 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal