diff options
Diffstat (limited to 'py/gc.c')
| -rw-r--r-- | py/gc.c | 26 |
1 files changed, 17 insertions, 9 deletions
@@ -203,11 +203,13 @@ bool gc_is_locked(void) { #endif #endif -STATIC void gc_drain_stack(void) { - while (MP_STATE_MEM(gc_sp) > MP_STATE_MEM(gc_stack)) { - // pop the next block off the stack - size_t block = *--MP_STATE_MEM(gc_sp); - +// Take the given block as the topmost block on the stack. Check all it's +// children: mark the unmarked child blocks and put those newly marked +// blocks on the stack. When all children have been checked, pop off the +// topmost block on the stack and repeat with that one. +STATIC void gc_mark_subtree(size_t block) { + // Start with the block passed in the argument. + for (;;) { // work out number of consecutive blocks in the chain starting with this one size_t n_blocks = 0; do { @@ -233,6 +235,14 @@ STATIC void gc_drain_stack(void) { } } } + + // Are there any blocks on the stack? + if (MP_STATE_MEM(gc_sp) <= MP_STATE_MEM(gc_stack)) { + break; // No, stack is empty, we're done. + } + + // pop the next block off the stack + block = *--MP_STATE_MEM(gc_sp); } } @@ -245,8 +255,7 @@ STATIC void gc_deal_with_stack_overflow(void) { for (size_t block = 0; block < MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; block++) { // trace (again) if mark bit set if (ATB_GET_KIND(block) == AT_MARK) { - *MP_STATE_MEM(gc_sp)++ = block; - gc_drain_stack(); + gc_mark_subtree(block); } } } @@ -339,8 +348,7 @@ void gc_collect_root(void **ptrs, size_t len) { // an unmarked head, mark it, and push it on gc stack TRACE_MARK(block, ptr); ATB_HEAD_TO_MARK(block); - *MP_STATE_MEM(gc_sp)++ = block; - gc_drain_stack(); + gc_mark_subtree(block); } } } |