The unpac monorepo manager self-hosting as a monorepo using unpac
manual: add explanation about 'simple' GC rules (#14273)
* manual: add explanation about 'simple' GC rules
* Review
authored by
Nicolás Ojeda Bär
and committed by
GitHub
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manual/src/cmds/intf-c.etex
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\subsection{ss:c-simple-gc-harmony}{Simple interface}
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In general, any variable in C code that references a heap-allocated OCaml value
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must be known to the runtime when the GC runs, as references to any objects
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moved by the GC need to be updated. Modifications of mutable fields must also be
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tracked by the GC for correctness. Listed below are simple rules to achieve
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this. In some cases, the rules dictate registration of variables that may not be
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technically needed (eg because the referenced OCaml value is an immediate, or
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because the GC is guaranteed not to be invoked during the lifetime of the
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variable). However, trying to optimize root registration is a common source of
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safety bugs, so it is strongly recommended to follow the rules below in most
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cases. The implementation of the root registration mechanism is efficient and
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will not typically result in any performance penalty.
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All the macros described in this section are declared in the
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"<caml/memory.h>" header file.
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