This is significantly faster than checking BUILTIN_TYPEs because we access significantly less memory. We also use popcount to count entire words at a time.
The only functional difference from the previous implementation is that T_ZOMBIE objects will no longer be counted. However those are temporary objects which should be small in number, and this method has always been an estimate.
Added by jhawthorn (John Hawthorn) almost 6 years ago
Count pinned slots using only bitmap
This is significantly faster than checking BUILTIN_TYPEs because we
access significantly less memory. We also use popcount to count entire
words at a time.
The only functional difference from the previous implementation is that
T_ZOMBIE objects will no longer be counted. However those are temporary
objects which should be small in number, and this method has always been
an estimate.