Prevent deopt when assigning double values to typed arrays

src/objects.cc

 // Copyright 2011 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 9084 matching lines @@
   }
   ASSERT_NE(NULL, result_double);
   result_double->set_value(static_cast<double>(result));
   return result_double;
 }
 
 
 Object* ExternalPixelArray::SetValue(uint32_t index, Object* value) {
   uint8_t clamped_value = 0;
   if (index < static_cast<uint32_t>(length())) {
-    if (value->IsSmi()) {
-      int int_value = Smi::cast(value)->value();
-      if (int_value < 0) {
-        clamped_value = 0;
-      } else if (int_value > 255) {
-        clamped_value = 255;
-      } else {
-        clamped_value = static_cast<uint8_t>(int_value);
-      }
-    } else if (value->IsHeapNumber()) {
-      double double_value = HeapNumber::cast(value)->value();
-      if (!(double_value > 0)) {
-        // NaN and less than zero clamp to zero.
-        clamped_value = 0;
-      } else if (double_value > 255) {
-        // Greater than 255 clamp to 255.
-        clamped_value = 255;
-      } else {
-        // Other doubles are rounded to the nearest integer.
-        clamped_value = static_cast<uint8_t>(double_value + 0.5);
-      }
-    } else {
-      // Clamp undefined to zero (default). All other types have been
-      // converted to a number type further up in the call chain.
-      ASSERT(value->IsUndefined());
-    }
+    clamped_value = NumberToClampedUInt8(value);
     set(index, clamped_value);
   }
   return Smi::FromInt(clamped_value);
 }
 
 
 template<typename ExternalArrayClass, typename ValueType>
 static MaybeObject* ExternalArrayIntSetter(Heap* heap,
                                            ExternalArrayClass* receiver,
                                            uint32_t index,
@@ skipping 1176 matching lines @@
   if (break_point_objects()->IsUndefined()) return 0;
   // Single beak point.
   if (!break_point_objects()->IsFixedArray()) return 1;
   // Multiple break points.
   return FixedArray::cast(break_point_objects())->length();
 }
 #endif
 
 
 } }  // namespace v8::internal