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91 lines
3.9 KiB
C
91 lines
3.9 KiB
C
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/*
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* Copyright (c) 1999 by Silicon Graphics. All rights reserved.
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*
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* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
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* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
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*
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* Permission is hereby granted to use or copy this program
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* for any purpose, provided the above notices are retained on all copies.
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* Permission to modify the code and to distribute modified code is granted,
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* provided the above notices are retained, and a notice that the code was
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* modified is included with the above copyright notice.
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*/
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/*
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* THIS IMPLEMENTATION FOR THIS INTERFACE IS INCOMPLETE.
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* NONE OF THIS HAS BEEN TESTED. DO NOT USE.
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*
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* Comments on the interface are appreciated, especially from
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* potential users of the interface.
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*
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* This is a Bartlett style copying collector for young objects.
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* We assume for now that all objects allocated through this
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* mechanism have pointers only in the first BITMAP_BITS words.
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* (On a 32-bit machine, BITMAP_BITS is 30.)
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* Objects allocated in this manner should be rarely referenced
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* by objects not allocated either through this interface, or through
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* the typed allocation interface.
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* If this interface is used, we assume that type information provided
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* through either this or the typed allocation interface is valid
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* in a stronger sense:
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*
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* 1) No pointers are stored in fields not marked as such.
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* (Otherwise it is only necessary that objects referenced by
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* fields marked as nonpointers are also reachable via another
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* path.)
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* 2) Values stored in pointer fields are either not addresses in
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* the heap, or they really are pointers. In the latter case, it
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* is acceptable to move the object they refer to, and to update
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* the pointer.
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*
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* GC_free may not be invoked on objects allocated with GC_copying_malloc.
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*
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* No extra space is added to the end of objects allocated through this
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* interface. If the client needs to maintain pointers past the
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* end, the size should be explicitly padded.
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*
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* We assume that calls to this will usually be compiler generated.
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* Hence the interface is allowed to be a bit ugly in return for speed.
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*/
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#include "gc_copy_descr.h"
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/* GC_copy_descr.h must define */
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/* GC_SIZE_FROM_DESCRIPTOR(descr) and */
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/* GC_BIT_MAP_FROM_DESCRIPTOR(descr). */
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/* It may either be the GC supplied version of the header file, or a */
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/* client specific one that derives the information from a client- */
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/* specific type descriptor. */
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typedef GC_PTR GC_copy_alloc_state;
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/* Current allocator state. */
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/* Multiple allocation states */
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/* may be used for concurrent */
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/* allocation, or to enhance */
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/* locality. */
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/* Should be treated as opaque. */
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/* Allocate a memory block of size given in the descriptor, and with */
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/* pointer layout given by the descriptor. The resulting block may not */
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/* be cleared, and should immediately be initialized by the client. */
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/* (A concurrent GC may see an uninitialized pointer field. If it */
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/* points outside the nursery, that's fine. If it points inside, it */
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/* may retain an object, and be relocated. But that's also fine, since */
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/* the new value will be immediately overwritten. */
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/* This variant acquires the allocation lock, and uses a default */
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/* global allocation state. */
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GC_PTR GC_copying_malloc(GC_copy_descriptor);
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/* A variant of the above that does no locking on the fast path, */
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/* and passes an explicit pointer to an allocation state. */
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/* The allocation state is updated. */
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/* There will eventually need to be a macro or inline function version */
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/* of this. */
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GC_PTR GC_copying_malloc2(GC_copy_descriptor, GC_copy_alloc_state *);
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/* Initialize an allocation state so that it can be used for */
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/* allocation. This implicitly reserves a small section of the */
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/* nursery for use with this allocator. */
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void GC_init_copy_alloc_state(GC_copy_alloc_state *);
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