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-rw-r--r--dbg_mlc.c180
1 files changed, 160 insertions, 20 deletions
diff --git a/dbg_mlc.c b/dbg_mlc.c
index 8151625..6483256 100644
--- a/dbg_mlc.c
+++ b/dbg_mlc.c
@@ -12,8 +12,11 @@
* provided the above notices are retained, and a notice that the code was
* modified is included with the above copyright notice.
*/
-/* Boehm, October 9, 1995 1:16 pm PDT */
+# define I_HIDE_POINTERS
# include "gc_priv.h"
+# ifdef KEEP_BACK_PTRS
+# include "backptr.h"
+# endif
void GC_default_print_heap_obj_proc();
GC_API void GC_register_finalizer_no_order
@@ -31,6 +34,14 @@ GC_API void GC_register_finalizer_no_order
/* Object header */
typedef struct {
+# ifdef KEEP_BACK_PTRS
+ ptr_t oh_back_ptr;
+# define MARKED_FOR_FINALIZATION (ptr_t)(-1)
+ /* Object was marked because it is finalizable. */
+# ifdef ALIGN_DOUBLE
+ word oh_dummy;
+# endif
+# endif
char * oh_string; /* object descriptor string */
word oh_int; /* object descriptor integers */
# ifdef NEED_CALLINFO
@@ -85,6 +96,134 @@ ptr_t p;
return(FALSE);
}
+#ifdef KEEP_BACK_PTRS
+ /* Store back pointer to source in dest, if that appears to be possible. */
+ /* This is not completely safe, since we may mistakenly conclude that */
+ /* dest has a debugging wrapper. But the error probability is very */
+ /* small, and this shouldn't be used in production code. */
+ /* We assume that dest is the real base pointer. Source will usually */
+ /* be a pointer to the interior of an object. */
+ void GC_store_back_pointer(ptr_t source, ptr_t dest)
+ {
+ if (GC_has_debug_info(dest)) {
+ ((oh *)dest) -> oh_back_ptr = (ptr_t)HIDE_POINTER(source);
+ }
+ }
+
+ void GC_marked_for_finalization(ptr_t dest) {
+ GC_store_back_pointer(MARKED_FOR_FINALIZATION, dest);
+ }
+
+ /* Store information about the object referencing dest in *base_p */
+ /* and *offset_p. */
+ /* source is root ==> *base_p = 0, *offset_p = address */
+ /* 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. */
+ GC_ref_kind GC_get_back_ptr_info(void *dest, void **base_p, size_t *offset_p)
+ {
+ oh * hdr = (oh *)GC_base(dest);
+ ptr_t bp;
+ ptr_t bp_base;
+ if (!GC_has_debug_info((ptr_t) hdr)) return GC_NO_SPACE;
+ bp = hdr -> oh_back_ptr;
+ if (MARKED_FOR_FINALIZATION == bp) return GC_FINALIZER_REFD;
+ if (0 == bp) return GC_UNREFERENCED;
+ bp = REVEAL_POINTER(bp);
+ bp_base = GC_base(bp);
+ if (0 == bp_base) {
+ *base_p = bp;
+ *offset_p = 0;
+ return GC_REFD_FROM_ROOT;
+ } else {
+ if (GC_has_debug_info(bp_base)) bp_base += sizeof(oh);
+ *base_p = bp_base;
+ *offset_p = bp - bp_base;
+ return GC_REFD_FROM_HEAP;
+ }
+ }
+
+ /* 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)
+ {
+ int i;
+ int heap_offset = random() % GC_heapsize;
+ for (i = 0; i < GC_n_heap_sects; ++ i) {
+ int size = GC_heap_sects[i].hs_bytes;
+ if (heap_offset < size) {
+ return GC_heap_sects[i].hs_start + heap_offset;
+ } else {
+ heap_offset -= size;
+ }
+ }
+ ABORT("GC_generate_random_heap_address: size inconsistency");
+ /*NOTREACHED*/
+ return 0;
+ }
+
+ /* Generate a random address inside a valid marked heap object. */
+ void *GC_generate_random_valid_address(void)
+ {
+ ptr_t result;
+ ptr_t base;
+ for (;;) {
+ result = GC_generate_random_heap_address();
+ base = GC_base(result);
+ if (0 == base) continue;
+ if (!GC_is_marked(base)) continue;
+ return result;
+ }
+ }
+
+ /* Force a garbage collection and generate a backtrace from a */
+ /* random heap address. */
+ void GC_generate_random_backtrace(void)
+ {
+ void * current;
+ int i;
+ void * base;
+ size_t offset;
+ GC_ref_kind source;
+ GC_gcollect();
+ current = GC_generate_random_valid_address();
+ GC_printf1("Chose address 0x%lx in object\n", (unsigned long)current);
+ GC_print_heap_obj(GC_base(current));
+ GC_err_printf0("\n");
+ for (i = 0; ; ++i) {
+ source = GC_get_back_ptr_info(current, &base, &offset);
+ if (GC_UNREFERENCED == source) {
+ GC_err_printf0("Reference could not be found\n");
+ goto out;
+ }
+ if (GC_NO_SPACE == source) {
+ GC_err_printf0("No debug info in object: Can't find reference\n");
+ goto out;
+ }
+ GC_err_printf1("Reachable via %d levels of pointers from ",
+ (unsigned long)i);
+ switch(source) {
+ case GC_REFD_FROM_ROOT:
+ GC_err_printf1("root at 0x%lx\n", (unsigned long)base);
+ goto out;
+ case GC_FINALIZER_REFD:
+ GC_err_printf0("list of finalizable objects\n");
+ goto out;
+ case GC_REFD_FROM_HEAP:
+ GC_err_printf1("offset %ld in object:\n", (unsigned long)offset);
+ /* Take GC_base(base) to get real base, i.e. header. */
+ GC_print_heap_obj(GC_base(base));
+ GC_err_printf0("\n");
+ break;
+ }
+ current = base;
+ }
+ out:;
+ }
+
+#endif /* KEEP_BACK_PTRS */
+
/* Store debugging info into p. Return displaced pointer. */
/* Assumes we don't hold allocation lock. */
ptr_t GC_store_debug_info(p, sz, string, integer)
@@ -100,6 +239,9 @@ word integer;
/* But that's expensive. And this way things should only appear */
/* inconsistent while we're in the handler. */
LOCK();
+# ifdef KEEP_BACK_PTRS
+ ((oh *)p) -> oh_back_ptr = 0;
+# endif
((oh *)p) -> oh_string = string;
((oh *)p) -> oh_int = integer;
((oh *)p) -> oh_sz = sz;
@@ -110,7 +252,7 @@ word integer;
return((ptr_t)result);
}
-/* Check the object with debugging info at p */
+/* Check the object with debugging info at ohdr */
/* return NIL if it's OK. Else return clobbered */
/* address. */
ptr_t GC_check_annotated_obj(ohdr)
@@ -408,31 +550,29 @@ GC_PTR p;
GC_err_printf0(
"GC_debug_free: found previously deallocated (?) object at ");
} else {
- GC_err_printf0("GC_debug_free: found smashed object at ");
+ GC_err_printf0("GC_debug_free: found smashed location at ");
}
GC_print_smashed_obj(p, clobbered);
}
/* Invalidate size */
((oh *)base) -> oh_sz = GC_size(base);
}
-# ifdef FIND_LEAK
+ if (GC_find_leak) {
GC_free(base);
-# else
- {
- register hdr * hhdr = HDR(p);
- GC_bool uncollectable = FALSE;
+ } else {
+ register hdr * hhdr = HDR(p);
+ GC_bool uncollectable = FALSE;
- if (hhdr -> hb_obj_kind == UNCOLLECTABLE) {
- uncollectable = TRUE;
- }
-# ifdef ATOMIC_UNCOLLECTABLE
- if (hhdr -> hb_obj_kind == AUNCOLLECTABLE) {
- uncollectable = TRUE;
- }
-# endif
- if (uncollectable) GC_free(base);
+ if (hhdr -> hb_obj_kind == UNCOLLECTABLE) {
+ uncollectable = TRUE;
}
-# endif
+# ifdef ATOMIC_UNCOLLECTABLE
+ if (hhdr -> hb_obj_kind == AUNCOLLECTABLE) {
+ uncollectable = TRUE;
+ }
+# endif
+ if (uncollectable) GC_free(base);
+ } /* !GC_find_leak */
}
# ifdef __STDC__
@@ -491,7 +631,7 @@ GC_PTR p;
}
clobbered = GC_check_annotated_obj((oh *)base);
if (clobbered != 0) {
- GC_err_printf0("GC_debug_realloc: found smashed object at ");
+ GC_err_printf0("GC_debug_realloc: found smashed location at ");
GC_print_smashed_obj(p, clobbered);
}
old_sz = ((oh *)base) -> oh_sz;
@@ -528,7 +668,7 @@ word dummy;
if (clobbered != 0) {
GC_err_printf0(
- "GC_check_heap_block: found smashed object at ");
+ "GC_check_heap_block: found smashed location at ");
GC_print_smashed_obj((ptr_t)p, clobbered);
}
}