Libraries that are both nogc and gc?
Ola Fosheim Grøstad
ola.fosheim.grostad at gmail.com
Sat Nov 21 12:14:58 UTC 2020
Let's assume that all the useful D constructs like class objects,
dynamic arrays, associative arrays, delegates, exceptions are
allocated with a reference count at a negative offset (which can
be optimized away during static analysis).
Then it should be possible to write library code that supports
both gc and nogc. It seems to me that this would be possible if:
- all functions are templated behind the scenes with a hidden
template parameter "allocator_strategy". This parameter is
inherited from the calling context unless it is explicitly set.
- library aggregates (classes structs) have to use a specific
notation for owning pointers and nonowning pointers. This will
also speed up GC collection if the collector is precise (it does
not have to follow nonowning pointers).
If the context is "allocator_gc" then it will just use raw
pointers, and mark the ones that are owning for tracing and also
be careful about using gc_root IR intrinsics when calling
C-functions to makes sure that the pointer is live during the
If the context is "allocator_arc" then it will use an ARC pointer
and emit acquire/release (retain/release) intrinsics at the IR
level (or AST).
If the context is "allocator_bump" then it will just emit C-like
Please note that this is static, not dynamic, so it should yield
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