Status: Accepted
Owner: ----
CC: [email protected]
Labels: Type-FeatureRequest Priority-Low
New issue 1581 by [email protected]: [Optimization] New makes an
unnecessary copy of the constructor's arguments.
http://code.google.com/p/v8/issues/detail?id=1581
JSConstructStubXXX always constructs a new frame, with a new copy of all
the arguments, before calling the constructor. This is needed because the
constructor cannot be a tail call, because if the constructor returns an
object, that is the result of "new", otherwise the allocated object is.
We can make a tail call to the constructor, if we do this final check in
the generated code for "new". "new" should allocate an output slot for the
allocated object, then push the (dummy) receiver and the arguments. The
stub will store the object in the slot, and as the receiver, and tail call
the function. Then the generated code will check the result, and use it or
the new object as the value of new. This could also be a stub to do the
check.
I'll leave this bug available, if anyone wants to tackle it before me.
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