RFR (M): 8188813: Generalize OrderAccess to use templates

Erik Österlund erik.osterlund at oracle.com
Thu Oct 5 13:55:45 UTC 2017


Now that Atomic has been generalized with templates, the same should to 
be done to OrderAccess.



Testing: mach5 hs-tier3

Since Atomic already has a mechanism for type checking generic arguments 
for Atomic::load/store, and OrderAccess also is a bunch of semantically 
decorated loads and stores, I decided to reuse the template wheel that 
was already invented (Atomic::LoadImpl and Atomic::StoreImpl).
Therefore, I made OrderAccess privately inherit Atomic so that this 
infrastructure could be reused. A whole bunch of code has been nuked 
with this generalization.

It is worth noting that I have added PrimitiveConversion functionality 
for doubles and floats which translates to using the union trick for 
casting double to and from int64_t and float to and from int32_t when 
passing down doubles and ints to the API. I need the former two, because 
Java supports volatile double and volatile float, and therefore runtime 
support for that needs to be able to use floats and doubles. I also 
added PrimitiveConversion functionality for the subclasses of oop 
(instanceOop and friends). The base class oop already supported this, so 
it seemed natural that the subclasses should support it too.


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