| /* |
| * 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. |
| */ |
| |
| #ifndef GC_BACKPTR_H |
| #define GC_BACKPTR_H |
| /* 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 reference info available. */ |
| GC_NO_SPACE, /* Dest not allocated with debug alloc */ |
| GC_REFD_FROM_ROOT, /* Referenced directly by root *base_p */ |
| GC_REFD_FROM_REG, /* Referenced from a register, i.e. */ |
| /* a root without an address. */ |
| 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); |
| |
| /* Print a backtrace from a specific address. Used by the */ |
| /* above. The client should call GC_gcollect() immediately */ |
| /* before invocation. */ |
| void GC_print_backtrace(void *); |
| |
| #endif /* GC_BACKPTR_H */ |