diff --git a/py/gc.c b/py/gc.c index 338803dc245cc..2cf4dbb64a83b 100644 --- a/py/gc.c +++ b/py/gc.c @@ -311,8 +311,9 @@ void gc_add(void *start, void *end) { #if MICROPY_GC_SPLIT_HEAP_AUTO // CIRCUITPY-CHANGE: Added function to compute heap size with selective collect table static size_t compute_heap_size(size_t total_blocks) { - // Add two blocks to account for allocation alignment. - total_blocks += 2; + // Round up to the nearest multiple of BLOCKS_PER_ATB. Partial ATB blocks aren't supported and + // will result in a heap that is too small. + total_blocks = ((total_blocks + BLOCKS_PER_ATB - 1) / BLOCKS_PER_ATB) * BLOCKS_PER_ATB; size_t atb_bytes = (total_blocks + BLOCKS_PER_ATB - 1) / BLOCKS_PER_ATB; size_t ftb_bytes = 0; size_t ctb_bytes = 0; @@ -326,12 +327,13 @@ static size_t compute_heap_size(size_t total_blocks) { // Compute bytes needed to build a heap with total_blocks blocks. size_t total_heap = - atb_bytes + sizeof(mp_state_mem_area_t) + + atb_bytes + + ALLOC_TABLE_GAP_BYTE + ftb_bytes + ctb_bytes + pool_bytes - + ALLOC_TABLE_GAP_BYTE - + sizeof(mp_state_mem_area_t); + + BYTES_PER_BLOCK; // Extra block of bytes to account for end pointer alignment // Round up size to the nearest multiple of BYTES_PER_BLOCK. total_heap = (total_heap + BYTES_PER_BLOCK - 1) / BYTES_PER_BLOCK;