mirror of
git://gcc.gnu.org/git/gcc.git
synced 2024-12-21 11:19:25 +08:00
57 lines
2.4 KiB
C
57 lines
2.4 KiB
C
/*
|
|
* This is a simple API to implement pointer back tracing, i.e.
|
|
* to answer questions such as "who is pointing to this" or
|
|
* "why is this object being retained by the collector"
|
|
*
|
|
* This API assumes that we have an ANSI C compiler.
|
|
*
|
|
* Most of these calls yield useful information on only after
|
|
* a garbage collection. Usually the client will first force
|
|
* a full collection and then gather information, preferably
|
|
* before much intervening allocation.
|
|
*
|
|
* The implementation of the interface is only about 99.9999%
|
|
* correct. It is intended to be good enough for profiling,
|
|
* but is not intended to be used with production code.
|
|
*
|
|
* Results are likely to be much more useful if all allocation is
|
|
* accomplished through the debugging allocators.
|
|
*
|
|
* The implementation idea is due to A. Demers.
|
|
*/
|
|
|
|
/* Store information about the object referencing dest in *base_p */
|
|
/* and *offset_p. */
|
|
/* If multiple objects or roots point to dest, the one reported */
|
|
/* will be the last on used by the garbage collector to trace the */
|
|
/* object. */
|
|
/* source is root ==> *base_p = address, *offset_p = 0 */
|
|
/* source is heap object ==> *base_p != 0, *offset_p = offset */
|
|
/* Returns 1 on success, 0 if source couldn't be determined. */
|
|
/* Dest can be any address within a heap object. */
|
|
typedef enum { GC_UNREFERENCED, /* No refence info available. */
|
|
GC_NO_SPACE, /* Dest not allocated with debug alloc */
|
|
GC_REFD_FROM_ROOT, /* Referenced directly by root *base_p */
|
|
GC_REFD_FROM_HEAP, /* Referenced from another heap obj. */
|
|
GC_FINALIZER_REFD /* Finalizable and hence accessible. */
|
|
} GC_ref_kind;
|
|
|
|
GC_ref_kind GC_get_back_ptr_info(void *dest, void **base_p, size_t *offset_p);
|
|
|
|
/* Generate a random heap address. */
|
|
/* The resulting address is in the heap, but */
|
|
/* not necessarily inside a valid object. */
|
|
void * GC_generate_random_heap_address(void);
|
|
|
|
/* Generate a random address inside a valid marked heap object. */
|
|
void * GC_generate_random_valid_address(void);
|
|
|
|
/* Force a garbage collection and generate a backtrace from a */
|
|
/* random heap address. */
|
|
/* This uses the GC logging mechanism (GC_printf) to produce */
|
|
/* output. It can often be called from a debugger. The */
|
|
/* source in dbg_mlc.c also serves as a sample client. */
|
|
void GC_generate_random_backtrace(void);
|
|
|
|
|