djsundog/circuitpython
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Correct collect of permanent pointers.

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The previous implementation managed to keep all but the head
pointer of the list.

Fixes #1814
This commit is contained in:
Scott Shawcroft 2019-04-18 15:44:44 -07:00
parent 70dd6167c0
commit 54ef87c6de
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GPG Key ID: FD0EDC4B6C53CA59
1 changed files with 15 additions and 12 deletions
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27
py/gc.c
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@ -345,6 +345,19 @@ STATIC void gc_sweep(void) {
}
}
// Mark can handle NULL pointers because it verifies the pointer is within the heap bounds.
STATIC void gc_mark(void* ptr) {
if (VERIFY_PTR(ptr)) {
size_t block = BLOCK_FROM_PTR(ptr);
if (ATB_GET_KIND(block) == AT_HEAD) {
// An unmarked head: mark it, and mark all its children
TRACE_MARK(block, ptr);
ATB_HEAD_TO_MARK(block);
gc_mark_subtree(block);
}
}
}
void gc_collect_start(void) {
GC_ENTER();
MP_STATE_MEM(gc_lock_depth)++;
@ -361,9 +374,7 @@ void gc_collect_start(void) {
size_t root_end = offsetof(mp_state_ctx_t, vm.qstr_last_chunk);
gc_collect_root(ptrs + root_start / sizeof(void*), (root_end - root_start) / sizeof(void*));
if (MP_STATE_MEM(permanent_pointers) != NULL) {
gc_collect_root(MP_STATE_MEM(permanent_pointers), BYTES_PER_BLOCK / sizeof(void*));
}
gc_mark(MP_STATE_MEM(permanent_pointers));
#if MICROPY_ENABLE_PYSTACK
// Trace root pointers from the Python stack.
@ -375,15 +386,7 @@ void gc_collect_start(void) {
void gc_collect_root(void **ptrs, size_t len) {
for (size_t i = 0; i < len; i++) {
void *ptr = ptrs[i];
if (VERIFY_PTR(ptr)) {
size_t block = BLOCK_FROM_PTR(ptr);
if (ATB_GET_KIND(block) == AT_HEAD) {
// An unmarked head: mark it, and mark all its children
TRACE_MARK(block, ptr);
ATB_HEAD_TO_MARK(block);
gc_mark_subtree(block);
}
}
gc_mark(ptr);
}
}