So I think this is going in the right direction. However, this should be
split
into 3 patches. There are three independent optimizations at hand.
1) Inlining a constant when the holder (either receiver or a prototype up
the
chain of the receiver) is an HConstant and the property is read-only
non-configurable, and
2) omitting the map-check for the holder if the holder is an HConstant and
we're
emitting a map-check only as guard for a property load of a read-only,
non-configurable property.
3) What you suggested regarding the types in VisitCall: if the receiver is
an
HConstant, we should adjust the types list accordingly.
Lets make 1) this patch, and figure out 2) in a separate patch; and land 3)
first to make sure that we don't have problems in 1).
My suggestions for the patches:
1) Move the code inlining the HConstant into BuildLoadNamedField if
checked_object->ActualValue()->IsConstant().
2) Don't delete nodes in place! Instead delay adding checks until they are
necessary:
- if the action is a load, delay the receiver mapcheck in BuildNamedAccess.
- in BuildMonomorphicAccess, add that map-check of the receiver if
info->has_holder(), but don't emit the map-check of the holder.
- in BuildLoadNamedField, emit the map-check of the incoming holder if the
holder is either not an HConstant (hence it's the receiver which is not an
HConstant), or the property is not read-only / non-configurable.
3) Update ComputeReceiverTypes to handle the case where
receiver->IsConstant().
That could should either trim down the receiver maps to a transition from
the
constant's map; or just add the constant's map as expected receiver type.
Does that sound reasonable?
Regards,
Toon
https://codereview.chromium.org/220163012/
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