here - Stefan-Marr.de

7. Implementation Approaches
method and its dynamic extent have to be executed in unenforced mode. If
the bit is not set, the execution mode of enforced or unenforced execution
remains unchanged on method activation.
Table 7.1.: RoarVM+OMOP Method Header: bit 30 is used to force unenforced
method execution.
UN P. #args #temporaries FS #literals Primitive 1
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
VM Interface Since part of the functionality is represented in the VM, and
part is represented in the Smalltalk image, both have to agree on a common
interface.
Intercession Handlers To enable the VM to invoke the intercession handlers,
it requires knowledge about the corresponding selectors. A common strategy
for such a case in Smalltalk VMs is the use of the specialObjectsArray. All
objects or classes the VM needs to be aware of are registered in this array
at a predetermined index. Similarly, the selectors for the intercession handlers
are encoded as an array that is referenced from a fixed index of this
specialObjectsArray.
The indices into the selector array are encoded in a header file of the VM.
This header file is generated by the image together with the array, but the VM
needs to be recompiled whenever the header and the array change.
Customization Constant The generated VM header file also encodes the bit
masks corresponding to the intercession points, which enable a decoding of
the customization constant of a domain to determine whether the domain
requires the intercession point to be taken. The image itself uses a consistency
check to verify that decoding of the customization is done correctly by both
VM and image. The customization constant itself is encoded in each domain
object in the field: domainCustomizations.
Initial Owner of Objects The domain objects have also a field to denote the
initial owner for newly created objects (initialDomainForNewObjects). Thus,
the VM can directly determine the new owner without the need for executing
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