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correctly track element pointer in heap snapshot (JuliaLang#90)
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Backports JuliaLang#51592.
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@d-netto
d-netto authored Oct 5, 2023
1 parent 1dd5dbf commit 6d98873
Showing 1 changed file with 42 additions and 10 deletions.
52 changes: 42 additions & 10 deletions src/gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2061,7 +2061,8 @@ STATIC_INLINE void gc_mark_objarray(jl_ptls_t ptls, jl_value_t *obj_parent, jl_v
// the first young object before starting this chunk
// (this also would be valid for young objects, but probably less beneficial)
for (; obj_begin < obj_end; obj_begin += step) {
new_obj = *obj_begin;
jl_value_t **slot = obj_begin;
new_obj = *slot;
if (new_obj != NULL) {
verify_parent2("obj array", obj_parent, obj_begin, "elem(%d)",
gc_slot_to_arrayidx(obj_parent, obj_begin));
Expand All @@ -2070,7 +2071,7 @@ STATIC_INLINE void gc_mark_objarray(jl_ptls_t ptls, jl_value_t *obj_parent, jl_v
nptr |= 1;
if (!gc_marked(o->header))
break;
gc_heap_snapshot_record_array_edge(obj_parent, &new_obj);
gc_heap_snapshot_record_array_edge(obj_parent, slot);
}
}
}
Expand All @@ -2092,12 +2093,13 @@ STATIC_INLINE void gc_mark_objarray(jl_ptls_t ptls, jl_value_t *obj_parent, jl_v
}
}
for (; obj_begin < scan_end; obj_begin += step) {
jl_value_t **slot = obj_begin;
new_obj = *obj_begin;
if (new_obj != NULL) {
verify_parent2("obj array", obj_parent, obj_begin, "elem(%d)",
gc_slot_to_arrayidx(obj_parent, obj_begin));
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_heap_snapshot_record_array_edge(obj_parent, &new_obj);
gc_heap_snapshot_record_array_edge(obj_parent, slot);
}
}
if (too_big) {
Expand Down Expand Up @@ -2128,7 +2130,8 @@ STATIC_INLINE void gc_mark_array8(jl_ptls_t ptls, jl_value_t *ary8_parent, jl_va
for (; ary8_begin < ary8_end; ary8_begin += elsize) {
int early_end = 0;
for (uint8_t *pindex = elem_begin; pindex < elem_end; pindex++) {
new_obj = ary8_begin[*pindex];
jl_value_t **slot = &ary8_begin[*pindex];
new_obj = *slot;
if (new_obj != NULL) {
verify_parent2("array", ary8_parent, &new_obj, "elem(%d)",
gc_slot_to_arrayidx(ary8_parent, ary8_begin));
Expand All @@ -2139,7 +2142,7 @@ STATIC_INLINE void gc_mark_array8(jl_ptls_t ptls, jl_value_t *ary8_parent, jl_va
early_end = 1;
break;
}
gc_heap_snapshot_record_array_edge(ary8_parent, &new_obj);
gc_heap_snapshot_record_array_edge(ary8_parent, slot);
}
}
if (early_end)
Expand All @@ -2165,12 +2168,13 @@ STATIC_INLINE void gc_mark_array8(jl_ptls_t ptls, jl_value_t *ary8_parent, jl_va
}
for (; ary8_begin < ary8_end; ary8_begin += elsize) {
for (uint8_t *pindex = elem_begin; pindex < elem_end; pindex++) {
new_obj = ary8_begin[*pindex];
jl_value_t **slot = &ary8_begin[*pindex];
new_obj = *slot;
if (new_obj != NULL) {
verify_parent2("array", ary8_parent, &new_obj, "elem(%d)",
gc_slot_to_arrayidx(ary8_parent, ary8_begin));
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_heap_snapshot_record_array_edge(ary8_parent, &new_obj);
gc_heap_snapshot_record_array_edge(ary8_parent, slot);
}
}
}
Expand All @@ -2193,7 +2197,34 @@ STATIC_INLINE void gc_mark_array16(jl_ptls_t ptls, jl_value_t *ary16_parent, jl_
jl_gc_markqueue_t *mq = &ptls->mark_queue;
jl_value_t *new_obj;
size_t elsize = ((jl_array_t *)ary16_parent)->elsize / sizeof(jl_value_t *);
// Decide whether need to chunk ary16
assert(elsize > 0);
// Decide whether need to chunk objary
if ((nptr & 0x2) == 0x2) {
// pre-scan this object: most of this object should be old, so look for
// the first young object before starting this chunk
// (this also would be valid for young objects, but probably less beneficial)
for (; ary16_begin < ary16_end; ary16_begin += elsize) {
int early_end = 0;
for (uint16_t *pindex = elem_begin; pindex < elem_end; pindex++) {
jl_value_t **slot = &ary16_begin[*pindex];
new_obj = *slot;
if (new_obj != NULL) {
verify_parent2("array", ary16_parent, &new_obj, "elem(%d)",
gc_slot_to_arrayidx(ary16_parent, ary16_begin));
jl_taggedvalue_t *o = jl_astaggedvalue(new_obj);
if (!gc_old(o->header))
nptr |= 1;
if (!gc_marked(o->header)){
early_end = 1;
break;
}
gc_heap_snapshot_record_array_edge(ary16_parent, slot);
}
}
if (early_end)
break;
}
}
size_t too_big = (ary16_end - ary16_begin) / GC_CHUNK_BATCH_SIZE > elsize; // use this order of operations to avoid idiv
jl_value_t **scan_end = ary16_end;
int pushed_chunk = 0;
Expand All @@ -2213,12 +2244,13 @@ STATIC_INLINE void gc_mark_array16(jl_ptls_t ptls, jl_value_t *ary16_parent, jl_
}
for (; ary16_begin < scan_end; ary16_begin += elsize) {
for (uint16_t *pindex = elem_begin; pindex < elem_end; pindex++) {
new_obj = ary16_begin[*pindex];
jl_value_t **slot = &ary16_begin[*pindex];
new_obj = *slot;
if (new_obj != NULL) {
verify_parent2("array", ary16_parent, &new_obj, "elem(%d)",
gc_slot_to_arrayidx(ary16_parent, ary16_begin));
gc_try_claim_and_push(mq, new_obj, &nptr);
gc_heap_snapshot_record_array_edge(ary16_parent, &new_obj);
gc_heap_snapshot_record_array_edge(ary16_parent, slot);
}
}
}
Expand Down

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