/* q are pointers to the object base, i.e. pointers to an oh. */
static void add_edge(ptr_t p, ptr_t q)
{
ptr_t old_back_ptr = GET_OH_BG_PTR(q);
back_edges * be, *be_cont;
word i;
static unsigned random_number = 13;
# define GOT_LUCKY_NUMBER (((++random_number) & 0x7f) == 0)
/* A not very random number we use to occasionally allocate a */
/* back_edges structure even for a single backward edge. This */
/* prevents us from repeatedly tracing back through very long */
/* chains, since we will have some place to store height and */
/* in_progress flags along the way. */
GC_ASSERT(p == GC_base(p) && q == GC_base(q));
if (!GC_HAS_DEBUG_INFO(q) || !GC_HAS_DEBUG_INFO(p)) {
/* This is really a misinterpreted free list link, since we saw */
/* a pointer to a free list. Dont overwrite it! */
return;
}
if (0 == old_back_ptr) {
SET_OH_BG_PTR(q, p);
if (GOT_LUCKY_NUMBER) ensure_struct(q);
return;
}
/* Check whether it was already in the list of predecessors. */
FOR_EACH_PRED(pred, q, { if (p == pred) return; });
static void reset_back_edge(ptr_t p, size_t n_bytes GC_ATTR_UNUSED,
word gc_descr GC_ATTR_UNUSED)
{
/* Skip any free list links, or dropped blocks */
if (GC_HAS_DEBUG_INFO(p)) {
ptr_t old_back_ptr = GET_OH_BG_PTR(p);
if ((word)old_back_ptr & FLAG_MANY) {
back_edges *be = (back_edges *)((word)old_back_ptr & ~FLAG_MANY);
if (!(be -> flags & RETAIN)) {
deallocate_back_edges(be);
SET_OH_BG_PTR(p, 0);
} else {
GC_ASSERT(GC_is_marked(p));
/* Back edges may point to objects that will not be retained. */
/* Delete them for now, but remember the height. */
/* Some will be added back at next GC. */
be -> n_edges = 0;
if (0 != be -> cont) {
deallocate_back_edges(be -> cont);
be -> cont = 0;
}
GC_ASSERT(GC_is_marked(p));
/* We only retain things for one GC cycle at a time. */
be -> flags &= ~RETAIN;
}
} else /* Simple back pointer */ {
/* Clear to avoid dangling pointer. */
SET_OH_BG_PTR(p, 0);
}
}
}
/*ARGSUSED*/
void GC_check_heap_block(struct hblk *hbp, word dummy)
{
struct hblkhdr * hhdr = HDR(hbp);
size_t sz = hhdr -> hb_sz;
size_t bit_no;
char *p, *plim;
p = hbp->hb_body;
bit_no = 0;
if (sz > MAXOBJBYTES) {
plim = p;
} else {
plim = hbp->hb_body + HBLKSIZE - sz;
}
/* go through all words in block */
while( p <= plim ) {
if( mark_bit_from_hdr(hhdr, bit_no)
&& GC_HAS_DEBUG_INFO((ptr_t)p)) {
ptr_t clobbered = GC_check_annotated_obj((oh *)p);
if (clobbered != 0) GC_add_smashed(clobbered);
}
bit_no += MARK_BIT_OFFSET(sz);
p += sz;
}
}
/* Dest can be any address within a heap object. */
GC_API GC_ref_kind GC_CALL 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;
# ifdef LINT2
/* Explicitly instruct the code analysis tool that */
/* GC_get_back_ptr_info is not expected to be called with an */
/* incorrect "dest" value. */
if (!hdr) ABORT("Invalid GC_get_back_ptr_info argument");
# endif
if (!GC_HAS_DEBUG_INFO((ptr_t) hdr)) return GC_NO_SPACE;
bp = GC_REVEAL_POINTER(hdr -> oh_back_ptr);
if (MARKED_FOR_FINALIZATION == bp) return GC_FINALIZER_REFD;
if (MARKED_FROM_REGISTER == bp) return GC_REFD_FROM_REG;
if (NOT_MARKED == bp) return GC_UNREFERENCED;
# if ALIGNMENT == 1
/* Heuristically try to fix off by 1 errors we introduced by */
/* insisting on even addresses. */
{
ptr_t alternate_ptr = bp + 1;
ptr_t target = *(ptr_t *)bp;
ptr_t alternate_target = *(ptr_t *)alternate_ptr;
if (alternate_target >= GC_least_plausible_heap_addr
&& alternate_target <= GC_greatest_plausible_heap_addr
&& (target < GC_least_plausible_heap_addr
|| target > GC_greatest_plausible_heap_addr)) {
bp = alternate_ptr;
}
}
# endif
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;
}
}
STATIC void GC_debug_print_heap_obj_proc(ptr_t p)
{
GC_ASSERT(I_DONT_HOLD_LOCK());
if (GC_HAS_DEBUG_INFO(p)) {
GC_print_obj(p);
} else {
GC_default_print_heap_obj_proc(p);
}
}
/* be a pointer to the interior of an object. */
GC_INNER void GC_store_back_pointer(ptr_t source, ptr_t dest)
{
if (GC_HAS_DEBUG_INFO(dest)) {
# ifdef PARALLEL_MARK
AO_store((volatile AO_t *)&((oh *)dest)->oh_back_ptr,
(AO_t)HIDE_BACK_PTR(source));
# else
((oh *)dest) -> oh_back_ptr = HIDE_BACK_PTR(source);
# endif
}
}
/* 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 = REVEAL_POINTER(hdr -> oh_back_ptr);
if (MARKED_FOR_FINALIZATION == bp) return GC_FINALIZER_REFD;
if (MARKED_FROM_REGISTER == bp) return GC_REFD_FROM_REG;
if (NOT_MARKED == bp) return GC_UNREFERENCED;
# if ALIGNMENT == 1
/* Heuristically try to fix off by 1 errors we introduced by */
/* insisting on even addresses. */
{
ptr_t alternate_ptr = bp + 1;
ptr_t target = *(ptr_t *)bp;
ptr_t alternate_target = *(ptr_t *)alternate_ptr;
if (alternate_target >= GC_least_plausible_heap_addr
&& alternate_target <= GC_greatest_plausible_heap_addr
&& (target < GC_least_plausible_heap_addr
|| target > GC_greatest_plausible_heap_addr)) {
bp = alternate_ptr;
}
}
# endif
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;
}
}
/* Avoid GC_apply_to_each_object for performance reasons. */
STATIC void GC_check_heap_block(struct hblk *hbp, word dummy GC_ATTR_UNUSED)
{
struct hblkhdr * hhdr = HDR(hbp);
word sz = hhdr -> hb_sz;
word bit_no;
char *p, *plim;
p = hbp->hb_body;
if (sz > MAXOBJBYTES) {
plim = p;
} else {
plim = hbp->hb_body + HBLKSIZE - sz;
}
/* go through all words in block */
for (bit_no = 0; (word)p <= (word)plim;
bit_no += MARK_BIT_OFFSET(sz), p += sz) {
if (mark_bit_from_hdr(hhdr, bit_no) && GC_HAS_DEBUG_INFO((ptr_t)p)) {
ptr_t clobbered = GC_check_annotated_obj((oh *)p);
if (clobbered != 0)
GC_add_smashed(clobbered);
}
}
}
/* be a pointer to the interior of an object. */
GC_INNER void GC_store_back_pointer(ptr_t source, ptr_t dest)
{
if (GC_HAS_DEBUG_INFO(dest)) {
((oh *)dest) -> oh_back_ptr = HIDE_BACK_PTR(source);
}
}
/* GC_deepest_obj to be the corresponding object. */
static void update_max_height(ptr_t p, size_t n_bytes GC_ATTR_UNUSED,
word gc_descr GC_ATTR_UNUSED)
{
if (GC_is_marked(p) && GC_HAS_DEBUG_INFO(p)) {
word p_height = 0;
ptr_t p_deepest_obj = 0;
ptr_t back_ptr;
back_edges *be = 0;
/* If we remembered a height last time, use it as a minimum. */
/* It may have increased due to newly unreachable chains pointing */
/* to p, but it can't have decreased. */
back_ptr = GET_OH_BG_PTR(p);
if (0 != back_ptr && ((word)back_ptr & FLAG_MANY)) {
be = (back_edges *)((word)back_ptr & ~FLAG_MANY);
if (be -> height != HEIGHT_UNKNOWN) p_height = be -> height;
}
{
ptr_t pred = GET_OH_BG_PTR(p);
back_edges *e = (back_edges *)((word)pred & ~FLAG_MANY);
word n_edges;
word total;
int local = 0;
if (((word)pred & FLAG_MANY) != 0) {
n_edges = e -> n_edges;
} else if (pred != NULL && ((word)pred & 1) == 0) {
/* A misinterpreted freelist link. */
n_edges = 1;
local = -1;
} else {
n_edges = 0;
}
for (total = 0; total < n_edges; ++total) {
if (local == MAX_IN) {
e = e -> cont;
local = 0;
}
if (local >= 0)
pred = e -> edges[local++];
/* Execute the following once for each predecessor pred of p */
/* in the points-to graph. */
if (!GC_is_marked(pred) && GC_HAS_DEBUG_INFO(pred)) {
word this_height = backwards_height(pred);
if (this_height > p_height) {
p_height = this_height;
p_deepest_obj = pred;
}
}
}
}
if (p_height > 0) {
/* Remember the height for next time. */
if (be == 0) {
ensure_struct(p);
back_ptr = GET_OH_BG_PTR(p);
be = (back_edges *)((word)back_ptr & ~FLAG_MANY);
}
be -> flags |= RETAIN;
be -> height = p_height;
be -> height_gc_no = (unsigned short)GC_gc_no;
}
if (p_height > GC_max_height) {
GC_max_height = p_height;
GC_deepest_obj = p_deepest_obj;
}
}
}
/* q are pointers to the object base, i.e. pointers to an oh. */
static void add_edge(ptr_t p, ptr_t q)
{
ptr_t pred = GET_OH_BG_PTR(q);
back_edges * be, *be_cont;
word i;
GC_ASSERT(p == GC_base(p) && q == GC_base(q));
if (!GC_HAS_DEBUG_INFO(q) || !GC_HAS_DEBUG_INFO(p)) {
/* This is really a misinterpreted free list link, since we saw */
/* a pointer to a free list. Don't overwrite it! */
return;
}
if (NULL == pred) {
static unsigned random_number = 13;
# define GOT_LUCKY_NUMBER (((++random_number) & 0x7f) == 0)
/* A not very random number we use to occasionally allocate a */
/* back_edges structure even for a single backward edge. This */
/* prevents us from repeatedly tracing back through very long */
/* chains, since we will have some place to store height and */
/* in_progress flags along the way. */
SET_OH_BG_PTR(q, p);
if (GOT_LUCKY_NUMBER) ensure_struct(q);
return;
}
/* Check whether it was already in the list of predecessors. */
{
back_edges *e = (back_edges *)((word)pred & ~FLAG_MANY);
word n_edges;
word total;
int local = 0;
if (((word)pred & FLAG_MANY) != 0) {
n_edges = e -> n_edges;
} else if (pred != NULL && ((word)pred & 1) == 0) {
/* A misinterpreted freelist link. */
n_edges = 1;
local = -1;
} else {
n_edges = 0;
}
for (total = 0; total < n_edges; ++total) {
if (local == MAX_IN) {
e = e -> cont;
local = 0;
}
if (local >= 0)
pred = e -> edges[local++];
if (pred == p)
return;
}
}
ensure_struct(q);
be = (back_edges *)((word)GET_OH_BG_PTR(q) & ~FLAG_MANY);
for (i = be -> n_edges, be_cont = be; i > MAX_IN; i -= MAX_IN)
be_cont = be_cont -> cont;
if (i == MAX_IN) {
be_cont -> cont = new_back_edges();
be_cont = be_cont -> cont;
i = 0;
}
be_cont -> edges[i] = p;
be -> n_edges++;
# ifdef DEBUG_PRINT_BIG_N_EDGES
if (GC_print_stats == VERBOSE && be -> n_edges == 100) {
GC_err_printf("The following object has big in-degree:\n");
GC_print_heap_obj(q);
}
# endif
}
