/* * This file is part of the MicroPython project, http://micropython.org/ * * The MIT License (MIT) * * Copyright (c) 2013, 2014 Damien P. George * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include #include #include #include "py/gc.h" #include "py/runtime.h" #include "supervisor/shared/safe_mode.h" #if MICROPY_ENABLE_GC #if MICROPY_DEBUG_VERBOSE // print debugging info #define DEBUG_PRINT (1) #define DEBUG_printf DEBUG_printf #else // don't print debugging info #define DEBUG_PRINT (0) #define DEBUG_printf(...) (void)0 #endif // Uncomment this if you want to use a debugger to capture state at every allocation and free. // #define LOG_HEAP_ACTIVITY 1 // make this 1 to dump the heap each time it changes #define EXTENSIVE_HEAP_PROFILING (0) // make this 1 to zero out swept memory to more eagerly // detect untraced object still in use #define CLEAR_ON_SWEEP (0) #define WORDS_PER_BLOCK ((MICROPY_BYTES_PER_GC_BLOCK) / BYTES_PER_WORD) #define BYTES_PER_BLOCK (MICROPY_BYTES_PER_GC_BLOCK) // ATB = allocation table byte // 0b00 = FREE -- free block // 0b01 = HEAD -- head of a chain of blocks // 0b10 = TAIL -- in the tail of a chain of blocks // 0b11 = MARK -- marked head block #define AT_FREE (0) #define AT_HEAD (1) #define AT_TAIL (2) #define AT_MARK (3) #define BLOCKS_PER_ATB (4) #define BLOCK_SHIFT(block) (2 * ((block) & (BLOCKS_PER_ATB - 1))) #define ATB_GET_KIND(block) ((MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] >> BLOCK_SHIFT(block)) & 3) #define ATB_ANY_TO_FREE(block) do { MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] &= (~(AT_MARK << BLOCK_SHIFT(block))); } while (0) #define ATB_FREE_TO_HEAD(block) do { MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] |= (AT_HEAD << BLOCK_SHIFT(block)); } while (0) #define ATB_FREE_TO_TAIL(block) do { MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] |= (AT_TAIL << BLOCK_SHIFT(block)); } while (0) #define ATB_HEAD_TO_MARK(block) do { MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] |= (AT_MARK << BLOCK_SHIFT(block)); } while (0) #define ATB_MARK_TO_HEAD(block) do { MP_STATE_MEM(gc_alloc_table_start)[(block) / BLOCKS_PER_ATB] &= (~(AT_TAIL << BLOCK_SHIFT(block))); } while (0) #define BLOCK_FROM_PTR(ptr) (((byte*)(ptr) - MP_STATE_MEM(gc_pool_start)) / BYTES_PER_BLOCK) #define PTR_FROM_BLOCK(block) (((block) * BYTES_PER_BLOCK + (uintptr_t)MP_STATE_MEM(gc_pool_start))) #define ATB_FROM_BLOCK(bl) ((bl) / BLOCKS_PER_ATB) #if MICROPY_ENABLE_FINALISER // FTB = finaliser table byte // if set, then the corresponding block may have a finaliser #define BLOCKS_PER_FTB (8) #define FTB_GET(block) ((MP_STATE_MEM(gc_finaliser_table_start)[(block) / BLOCKS_PER_FTB] >> ((block) & 7)) & 1) #define FTB_SET(block) do { MP_STATE_MEM(gc_finaliser_table_start)[(block) / BLOCKS_PER_FTB] |= (1 << ((block) & 7)); } while (0) #define FTB_CLEAR(block) do { MP_STATE_MEM(gc_finaliser_table_start)[(block) / BLOCKS_PER_FTB] &= (~(1 << ((block) & 7))); } while (0) #endif #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL #define GC_ENTER() mp_thread_mutex_lock(&MP_STATE_MEM(gc_mutex), 1) #define GC_EXIT() mp_thread_mutex_unlock(&MP_STATE_MEM(gc_mutex)) #else #define GC_ENTER() #define GC_EXIT() #endif #ifdef LOG_HEAP_ACTIVITY volatile uint32_t change_me; #pragma GCC push_options #pragma GCC optimize ("O0") void __attribute__ ((noinline)) gc_log_change(uint32_t start_block, uint32_t length) { change_me += start_block; change_me += length; // Break on this line. } #pragma GCC pop_options #endif // TODO waste less memory; currently requires that all entries in alloc_table have a corresponding block in pool void gc_init(void *start, void *end) { // align end pointer on block boundary end = (void*)((uintptr_t)end & (~(BYTES_PER_BLOCK - 1))); DEBUG_printf("Initializing GC heap: %p..%p = " UINT_FMT " bytes\n", start, end, (byte*)end - (byte*)start); // calculate parameters for GC (T=total, A=alloc table, F=finaliser table, P=pool; all in bytes): // T = A + F + P // F = A * BLOCKS_PER_ATB / BLOCKS_PER_FTB // P = A * BLOCKS_PER_ATB * BYTES_PER_BLOCK // => T = A * (1 + BLOCKS_PER_ATB / BLOCKS_PER_FTB + BLOCKS_PER_ATB * BYTES_PER_BLOCK) size_t total_byte_len = (byte*)end - (byte*)start; #if MICROPY_ENABLE_FINALISER MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len * BITS_PER_BYTE / (BITS_PER_BYTE + BITS_PER_BYTE * BLOCKS_PER_ATB / BLOCKS_PER_FTB + BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK); #else MP_STATE_MEM(gc_alloc_table_byte_len) = total_byte_len / (1 + BITS_PER_BYTE / 2 * BYTES_PER_BLOCK); #endif MP_STATE_MEM(gc_alloc_table_start) = (byte*)start; #if MICROPY_ENABLE_FINALISER size_t gc_finaliser_table_byte_len = (MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB + BLOCKS_PER_FTB - 1) / BLOCKS_PER_FTB; MP_STATE_MEM(gc_finaliser_table_start) = MP_STATE_MEM(gc_alloc_table_start) + MP_STATE_MEM(gc_alloc_table_byte_len); #endif size_t gc_pool_block_len = MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; MP_STATE_MEM(gc_pool_start) = (byte*)end - gc_pool_block_len * BYTES_PER_BLOCK; MP_STATE_MEM(gc_pool_end) = end; #if MICROPY_ENABLE_FINALISER assert(MP_STATE_MEM(gc_pool_start) >= MP_STATE_MEM(gc_finaliser_table_start) + gc_finaliser_table_byte_len); #endif // clear ATBs memset(MP_STATE_MEM(gc_alloc_table_start), 0, MP_STATE_MEM(gc_alloc_table_byte_len)); #if MICROPY_ENABLE_FINALISER // clear FTBs memset(MP_STATE_MEM(gc_finaliser_table_start), 0, gc_finaliser_table_byte_len); #endif // Set first free ATB index to the start of the heap. MP_STATE_MEM(gc_first_free_atb_index) = 0; // Set last free ATB index to the end of the heap. MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1; // Set the lowest long lived ptr to the end of the heap to start. This will be lowered as long // lived objects are allocated. MP_STATE_MEM(gc_lowest_long_lived_ptr) = (void*) PTR_FROM_BLOCK(MP_STATE_MEM(gc_alloc_table_byte_len * BLOCKS_PER_ATB)); // unlock the GC MP_STATE_MEM(gc_lock_depth) = 0; // allow auto collection MP_STATE_MEM(gc_auto_collect_enabled) = true; #if MICROPY_GC_ALLOC_THRESHOLD // by default, maxuint for gc threshold, effectively turning gc-by-threshold off MP_STATE_MEM(gc_alloc_threshold) = (size_t)-1; MP_STATE_MEM(gc_alloc_amount) = 0; #endif #if MICROPY_PY_THREAD mp_thread_mutex_init(&MP_STATE_MEM(gc_mutex)); #endif DEBUG_printf("GC layout:\n"); DEBUG_printf(" alloc table at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", MP_STATE_MEM(gc_alloc_table_start), MP_STATE_MEM(gc_alloc_table_byte_len), MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB); #if MICROPY_ENABLE_FINALISER DEBUG_printf(" finaliser table at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", MP_STATE_MEM(gc_finaliser_table_start), gc_finaliser_table_byte_len, gc_finaliser_table_byte_len * BLOCKS_PER_FTB); #endif DEBUG_printf(" pool at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", MP_STATE_MEM(gc_pool_start), gc_pool_block_len * BYTES_PER_BLOCK, gc_pool_block_len); } void gc_deinit() { // Run any finalizers before we stop using the heap. gc_sweep_all(); MP_STATE_MEM(gc_pool_start) = 0; } void gc_lock(void) { GC_ENTER(); MP_STATE_MEM(gc_lock_depth)++; GC_EXIT(); } void gc_unlock(void) { GC_ENTER(); MP_STATE_MEM(gc_lock_depth)--; GC_EXIT(); } bool gc_is_locked(void) { return MP_STATE_MEM(gc_lock_depth) != 0; } // ptr should be of type void* #define VERIFY_PTR(ptr) ( \ ((uintptr_t)(ptr) & (BYTES_PER_BLOCK - 1)) == 0 /* must be aligned on a block */ \ && ptr >= (void*)MP_STATE_MEM(gc_pool_start) /* must be above start of pool */ \ && ptr < (void*)MP_STATE_MEM(gc_pool_end) /* must be below end of pool */ \ ) #ifndef TRACE_MARK #if DEBUG_PRINT #define TRACE_MARK(block, ptr) DEBUG_printf("gc_mark(%p)\n", ptr) #else #define TRACE_MARK(block, ptr) #endif #endif // 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. size_t sp = 0; for (;;) { // work out number of consecutive blocks in the chain starting with this one size_t n_blocks = 0; do { n_blocks += 1; } while (ATB_GET_KIND(block + n_blocks) == AT_TAIL); // check this block's children void **ptrs = (void**)PTR_FROM_BLOCK(block); for (size_t i = n_blocks * BYTES_PER_BLOCK / sizeof(void*); i > 0; i--, ptrs++) { void *ptr = *ptrs; if (VERIFY_PTR(ptr)) { // Mark and push this pointer size_t childblock = BLOCK_FROM_PTR(ptr); if (ATB_GET_KIND(childblock) == AT_HEAD) { // an unmarked head, mark it, and push it on gc stack TRACE_MARK(childblock, ptr); ATB_HEAD_TO_MARK(childblock); if (sp < MICROPY_ALLOC_GC_STACK_SIZE) { MP_STATE_MEM(gc_stack)[sp++] = childblock; } else { MP_STATE_MEM(gc_stack_overflow) = 1; } } } } // Are there any blocks on the stack? if (sp == 0) { break; // No, stack is empty, we're done. } // pop the next block off the stack block = MP_STATE_MEM(gc_stack)[--sp]; } } STATIC void gc_deal_with_stack_overflow(void) { while (MP_STATE_MEM(gc_stack_overflow)) { MP_STATE_MEM(gc_stack_overflow) = 0; // scan entire memory looking for blocks which have been marked but not their children 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) { gc_mark_subtree(block); } } } } STATIC void gc_sweep(void) { #if MICROPY_PY_GC_COLLECT_RETVAL MP_STATE_MEM(gc_collected) = 0; #endif // free unmarked heads and their tails int free_tail = 0; for (size_t block = 0; block < MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; block++) { switch (ATB_GET_KIND(block)) { case AT_HEAD: #if MICROPY_ENABLE_FINALISER if (FTB_GET(block)) { mp_obj_base_t *obj = (mp_obj_base_t*)PTR_FROM_BLOCK(block); if (obj->type != NULL) { // if the object has a type then see if it has a __del__ method mp_obj_t dest[2]; mp_load_method_maybe(MP_OBJ_FROM_PTR(obj), MP_QSTR___del__, dest); if (dest[0] != MP_OBJ_NULL) { // load_method returned a method, execute it in a protected environment #if MICROPY_ENABLE_SCHEDULER mp_sched_lock(); #endif mp_call_function_1_protected(dest[0], dest[1]); #if MICROPY_ENABLE_SCHEDULER mp_sched_unlock(); #endif } } // clear finaliser flag FTB_CLEAR(block); } #endif free_tail = 1; ATB_ANY_TO_FREE(block); #if CLEAR_ON_SWEEP memset((void*)PTR_FROM_BLOCK(block), 0, BYTES_PER_BLOCK); #endif DEBUG_printf("gc_sweep(%x)\n", PTR_FROM_BLOCK(block)); #ifdef LOG_HEAP_ACTIVITY gc_log_change(block, 0); #endif #if MICROPY_PY_GC_COLLECT_RETVAL MP_STATE_MEM(gc_collected)++; #endif break; case AT_TAIL: if (free_tail) { ATB_ANY_TO_FREE(block); #if CLEAR_ON_SWEEP memset((void*)PTR_FROM_BLOCK(block), 0, BYTES_PER_BLOCK); #endif } break; case AT_MARK: ATB_MARK_TO_HEAD(block); free_tail = 0; break; } } } void gc_collect_start(void) { GC_ENTER(); MP_STATE_MEM(gc_lock_depth)++; #if MICROPY_GC_ALLOC_THRESHOLD MP_STATE_MEM(gc_alloc_amount) = 0; #endif MP_STATE_MEM(gc_stack_overflow) = 0; // Trace root pointers. This relies on the root pointers being organised // correctly in the mp_state_ctx structure. We scan nlr_top, dict_locals, // dict_globals, then the root pointer section of mp_state_vm. void **ptrs = (void**)(void*)&mp_state_ctx; size_t root_start = offsetof(mp_state_ctx_t, thread.dict_locals); 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 MICROPY_ENABLE_PYSTACK // Trace root pointers from the Python stack. ptrs = (void**)(void*)MP_STATE_THREAD(pystack_start); gc_collect_root(ptrs, (MP_STATE_THREAD(pystack_cur) - MP_STATE_THREAD(pystack_start)) / sizeof(void*)); #endif } 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); } } } } void gc_collect_end(void) { gc_deal_with_stack_overflow(); gc_sweep(); MP_STATE_MEM(gc_first_free_atb_index) = 0; MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1; MP_STATE_MEM(gc_lock_depth)--; GC_EXIT(); } void gc_sweep_all(void) { GC_ENTER(); MP_STATE_MEM(gc_lock_depth)++; MP_STATE_MEM(gc_stack_overflow) = 0; gc_collect_end(); } void gc_info(gc_info_t *info) { GC_ENTER(); info->total = MP_STATE_MEM(gc_pool_end) - MP_STATE_MEM(gc_pool_start); info->used = 0; info->free = 0; info->max_free = 0; info->num_1block = 0; info->num_2block = 0; info->max_block = 0; bool finish = false; for (size_t block = 0, len = 0, len_free = 0; !finish;) { size_t kind = ATB_GET_KIND(block); switch (kind) { case AT_FREE: info->free += 1; len_free += 1; len = 0; break; case AT_HEAD: info->used += 1; len = 1; break; case AT_TAIL: info->used += 1; len += 1; break; case AT_MARK: // shouldn't happen break; } block++; finish = (block == MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB); // Get next block type if possible if (!finish) { kind = ATB_GET_KIND(block); } if (finish || kind == AT_FREE || kind == AT_HEAD) { if (len == 1) { info->num_1block += 1; } else if (len == 2) { info->num_2block += 1; } if (len > info->max_block) { info->max_block = len; } if (finish || kind == AT_HEAD) { if (len_free > info->max_free) { info->max_free = len_free; } len_free = 0; } } } info->used *= BYTES_PER_BLOCK; info->free *= BYTES_PER_BLOCK; GC_EXIT(); } // We place long lived objects at the end of the heap rather than the start. This reduces // fragmentation by localizing the heap churn to one portion of memory (the start of the heap.) void *gc_alloc(size_t n_bytes, bool has_finaliser, bool long_lived) { size_t n_blocks = ((n_bytes + BYTES_PER_BLOCK - 1) & (~(BYTES_PER_BLOCK - 1))) / BYTES_PER_BLOCK; DEBUG_printf("gc_alloc(" UINT_FMT " bytes -> " UINT_FMT " blocks)\n", n_bytes, n_blocks); // check for 0 allocation if (n_blocks == 0) { return NULL; } if (MP_STATE_MEM(gc_pool_start) == 0) { reset_into_safe_mode(GC_ALLOC_OUTSIDE_VM); } GC_ENTER(); // check if GC is locked if (MP_STATE_MEM(gc_lock_depth) > 0) { GC_EXIT(); return NULL; } size_t found_block = 0xffffffff; size_t end_block; size_t start_block; size_t n_free; bool collected = !MP_STATE_MEM(gc_auto_collect_enabled); #if MICROPY_GC_ALLOC_THRESHOLD if (!collected && MP_STATE_MEM(gc_alloc_amount) >= MP_STATE_MEM(gc_alloc_threshold)) { GC_EXIT(); gc_collect(); collected = 1; GC_ENTER(); collected = true; } #endif bool keep_looking = true; // When we start searching on the other side of the crossover block we make sure to // perform a collect. That way we'll get the closest free block in our section. size_t crossover_block = BLOCK_FROM_PTR(MP_STATE_MEM(gc_lowest_long_lived_ptr)); while (keep_looking) { int8_t direction = 1; size_t start = MP_STATE_MEM(gc_first_free_atb_index); if (long_lived) { direction = -1; start = MP_STATE_MEM(gc_last_free_atb_index); } n_free = 0; // look for a run of n_blocks available blocks for (size_t i = start; keep_looking && MP_STATE_MEM(gc_first_free_atb_index) <= i && i <= MP_STATE_MEM(gc_last_free_atb_index); i += direction) { byte a = MP_STATE_MEM(gc_alloc_table_start)[i]; // Four ATB states are packed into a single byte. int j = 0; if (direction == -1) { j = 3; } for (; keep_looking && 0 <= j && j <= 3; j += direction) { if ((a & (0x3 << (j * 2))) == 0) { if (++n_free >= n_blocks) { found_block = i * BLOCKS_PER_ATB + j; keep_looking = false; } } else { if (!collected) { size_t block = i * BLOCKS_PER_ATB + j; if ((direction == 1 && block >= crossover_block) || (direction == -1 && block < crossover_block)) { keep_looking = false; } } n_free = 0; } } } if (n_free >= n_blocks) { break; } GC_EXIT(); // nothing found! if (collected) { return NULL; } DEBUG_printf("gc_alloc(" UINT_FMT "): no free mem, triggering GC\n", n_bytes); gc_collect(); collected = true; // Try again since we've hopefully freed up space. keep_looking = true; GC_ENTER(); } assert(found_block != 0xffffffff); // Found free space ending at found_block inclusive. // Also, set last free ATB index to block after last block we found, for start of // next scan. To reduce fragmentation, we only do this if we were looking // for a single free block, which guarantees that there are no free blocks // before this one. Also, whenever we free or shrink a block we must check // if this index needs adjusting (see gc_realloc and gc_free). if (!long_lived) { end_block = found_block; start_block = found_block - n_free + 1; if (n_blocks == 1) { MP_STATE_MEM(gc_first_free_atb_index) = (found_block + 1) / BLOCKS_PER_ATB; } } else { start_block = found_block; end_block = found_block + n_free - 1; if (n_blocks == 1) { MP_STATE_MEM(gc_last_free_atb_index) = (found_block - 1) / BLOCKS_PER_ATB; } } #ifdef LOG_HEAP_ACTIVITY gc_log_change(start_block, end_block - start_block + 1); #endif // mark first block as used head ATB_FREE_TO_HEAD(start_block); // mark rest of blocks as used tail // TODO for a run of many blocks can make this more efficient for (size_t bl = start_block + 1; bl <= end_block; bl++) { ATB_FREE_TO_TAIL(bl); } // get pointer to first block // we must create this pointer before unlocking the GC so a collection can find it void *ret_ptr = (void*)(MP_STATE_MEM(gc_pool_start) + start_block * BYTES_PER_BLOCK); DEBUG_printf("gc_alloc(%p)\n", ret_ptr); // If the allocation was long live then update the lowest value. Its used to trigger early // collects when allocations fail in their respective section. Its also used to ignore calls to // gc_make_long_lived where the pointer is already in the long lived section. if (long_lived && ret_ptr < MP_STATE_MEM(gc_lowest_long_lived_ptr)) { MP_STATE_MEM(gc_lowest_long_lived_ptr) = ret_ptr; } #if MICROPY_GC_ALLOC_THRESHOLD MP_STATE_MEM(gc_alloc_amount) += n_blocks; #endif GC_EXIT(); #if MICROPY_GC_CONSERVATIVE_CLEAR // be conservative and zero out all the newly allocated blocks memset((byte*)ret_ptr, 0, (end_block - start_block + 1) * BYTES_PER_BLOCK); #else // zero out the additional bytes of the newly allocated blocks // This is needed because the blocks may have previously held pointers // to the heap and will not be set to something else if the caller // doesn't actually use the entire block. As such they will continue // to point to the heap and may prevent other blocks from being reclaimed. memset((byte*)ret_ptr + n_bytes, 0, (end_block - start_block + 1) * BYTES_PER_BLOCK - n_bytes); #endif #if MICROPY_ENABLE_FINALISER if (has_finaliser) { // clear type pointer in case it is never set ((mp_obj_base_t*)ret_ptr)->type = NULL; // set mp_obj flag only if it has a finaliser GC_ENTER(); FTB_SET(start_block); GC_EXIT(); } #else (void)has_finaliser; #endif #if EXTENSIVE_HEAP_PROFILING gc_dump_alloc_table(); #endif return ret_ptr; } /* void *gc_alloc(mp_uint_t n_bytes) { return _gc_alloc(n_bytes, false); } void *gc_alloc_with_finaliser(mp_uint_t n_bytes) { return _gc_alloc(n_bytes, true); } */ // force the freeing of a piece of memory // TODO: freeing here does not call finaliser void gc_free(void *ptr) { GC_ENTER(); if (MP_STATE_MEM(gc_lock_depth) > 0) { // TODO how to deal with this error? GC_EXIT(); return; } DEBUG_printf("gc_free(%p)\n", ptr); if (ptr == NULL) { GC_EXIT(); } else { // get the GC block number corresponding to this pointer assert(VERIFY_PTR(ptr)); size_t block = BLOCK_FROM_PTR(ptr); assert(ATB_GET_KIND(block) == AT_HEAD); #if MICROPY_ENABLE_FINALISER FTB_CLEAR(block); #endif // set the last_free pointer to this block if it's earlier in the heap if (block / BLOCKS_PER_ATB < MP_STATE_MEM(gc_first_free_atb_index)) { MP_STATE_MEM(gc_first_free_atb_index) = block / BLOCKS_PER_ATB; } if (block / BLOCKS_PER_ATB > MP_STATE_MEM(gc_last_free_atb_index)) { MP_STATE_MEM(gc_last_free_atb_index) = block / BLOCKS_PER_ATB; } // free head and all of its tail blocks #ifdef LOG_HEAP_ACTIVITY gc_log_change(block, 0); #endif do { ATB_ANY_TO_FREE(block); block += 1; } while (ATB_GET_KIND(block) == AT_TAIL); GC_EXIT(); #if EXTENSIVE_HEAP_PROFILING gc_dump_alloc_table(); #endif } } size_t gc_nbytes(const void *ptr) { GC_ENTER(); if (VERIFY_PTR(ptr)) { size_t block = BLOCK_FROM_PTR(ptr); if (ATB_GET_KIND(block) == AT_HEAD) { // work out number of consecutive blocks in the chain starting with this on size_t n_blocks = 0; do { n_blocks += 1; } while (ATB_GET_KIND(block + n_blocks) == AT_TAIL); GC_EXIT(); return n_blocks * BYTES_PER_BLOCK; } } // invalid pointer GC_EXIT(); return 0; } bool gc_has_finaliser(const void *ptr) { #if MICROPY_ENABLE_FINALISER GC_ENTER(); if (VERIFY_PTR(ptr)) { bool has_finaliser = FTB_GET(BLOCK_FROM_PTR(ptr)); GC_EXIT(); return has_finaliser; } // invalid pointer GC_EXIT(); #else (void) ptr; #endif return false; } void *gc_make_long_lived(void *old_ptr) { // If its already in the long lived section then don't bother moving it. if (old_ptr >= MP_STATE_MEM(gc_lowest_long_lived_ptr)) { return old_ptr; } size_t n_bytes = gc_nbytes(old_ptr); if (n_bytes == 0) { return old_ptr; } bool has_finaliser = gc_has_finaliser(old_ptr); // Try and find a new area in the long lived section to copy the memory to. void* new_ptr = gc_alloc(n_bytes, has_finaliser, true); if (new_ptr == NULL) { return old_ptr; } else if (old_ptr > new_ptr) { // Return the old pointer if the new one is lower in the heap and free the new space. gc_free(new_ptr); return old_ptr; } // We copy everything over and let the garbage collection process delete the old copy. That way // we ensure we don't delete memory that has a second reference. (Though if there is we may // confuse things when its mutable.) memcpy(new_ptr, old_ptr, n_bytes); return new_ptr; } #if 0 // old, simple realloc that didn't expand memory in place void *gc_realloc(void *ptr, mp_uint_t n_bytes) { mp_uint_t n_existing = gc_nbytes(ptr); if (n_bytes <= n_existing) { return ptr; } else { bool has_finaliser; if (ptr == NULL) { has_finaliser = false; } else { #if MICROPY_ENABLE_FINALISER has_finaliser = FTB_GET(BLOCK_FROM_PTR((mp_uint_t)ptr)); #else has_finaliser = false; #endif } void *ptr2 = gc_alloc(n_bytes, has_finaliser); if (ptr2 == NULL) { return ptr2; } memcpy(ptr2, ptr, n_existing); gc_free(ptr); return ptr2; } } #else // Alternative gc_realloc impl void *gc_realloc(void *ptr_in, size_t n_bytes, bool allow_move) { // check for pure allocation if (ptr_in == NULL) { return gc_alloc(n_bytes, false, false); } // check for pure free if (n_bytes == 0) { gc_free(ptr_in); return NULL; } void *ptr = ptr_in; GC_ENTER(); if (MP_STATE_MEM(gc_lock_depth) > 0) { GC_EXIT(); return NULL; } // get the GC block number corresponding to this pointer assert(VERIFY_PTR(ptr)); size_t block = BLOCK_FROM_PTR(ptr); assert(ATB_GET_KIND(block) == AT_HEAD); // compute number of new blocks that are requested size_t new_blocks = (n_bytes + BYTES_PER_BLOCK - 1) / BYTES_PER_BLOCK; // Get the total number of consecutive blocks that are already allocated to // this chunk of memory, and then count the number of free blocks following // it. Stop if we reach the end of the heap, or if we find enough extra // free blocks to satisfy the realloc. Note that we need to compute the // total size of the existing memory chunk so we can correctly and // efficiently shrink it (see below for shrinking code). size_t n_free = 0; size_t n_blocks = 1; // counting HEAD block size_t max_block = MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; for (size_t bl = block + n_blocks; bl < max_block; bl++) { byte block_type = ATB_GET_KIND(bl); if (block_type == AT_TAIL) { n_blocks++; continue; } if (block_type == AT_FREE) { n_free++; if (n_blocks + n_free >= new_blocks) { // stop as soon as we find enough blocks for n_bytes break; } continue; } break; } // return original ptr if it already has the requested number of blocks if (new_blocks == n_blocks) { GC_EXIT(); return ptr_in; } // check if we can shrink the allocated area if (new_blocks < n_blocks) { // free unneeded tail blocks for (size_t bl = block + new_blocks, count = n_blocks - new_blocks; count > 0; bl++, count--) { ATB_ANY_TO_FREE(bl); } // set the last_free pointer to end of this block if it's earlier in the heap if ((block + new_blocks) / BLOCKS_PER_ATB < MP_STATE_MEM(gc_first_free_atb_index)) { MP_STATE_MEM(gc_first_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB; } if ((block + new_blocks) / BLOCKS_PER_ATB > MP_STATE_MEM(gc_last_free_atb_index)) { MP_STATE_MEM(gc_last_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB; } GC_EXIT(); #if EXTENSIVE_HEAP_PROFILING gc_dump_alloc_table(); #endif #ifdef LOG_HEAP_ACTIVITY gc_log_change(block, new_blocks); #endif return ptr_in; } // check if we can expand in place if (new_blocks <= n_blocks + n_free) { // mark few more blocks as used tail for (size_t bl = block + n_blocks; bl < block + new_blocks; bl++) { assert(ATB_GET_KIND(bl) == AT_FREE); ATB_FREE_TO_TAIL(bl); } GC_EXIT(); #if MICROPY_GC_CONSERVATIVE_CLEAR // be conservative and zero out all the newly allocated blocks memset((byte*)ptr_in + n_blocks * BYTES_PER_BLOCK, 0, (new_blocks - n_blocks) * BYTES_PER_BLOCK); #else // zero out the additional bytes of the newly allocated blocks (see comment above in gc_alloc) memset((byte*)ptr_in + n_bytes, 0, new_blocks * BYTES_PER_BLOCK - n_bytes); #endif #if EXTENSIVE_HEAP_PROFILING gc_dump_alloc_table(); #endif #ifdef LOG_HEAP_ACTIVITY gc_log_change(block, new_blocks); #endif return ptr_in; } #if MICROPY_ENABLE_FINALISER bool ftb_state = FTB_GET(block); #else bool ftb_state = false; #endif GC_EXIT(); if (!allow_move) { // not allowed to move memory block so return failure return NULL; } // can't resize inplace; try to find a new contiguous chain void *ptr_out = gc_alloc(n_bytes, ftb_state, false); // check that the alloc succeeded if (ptr_out == NULL) { return NULL; } DEBUG_printf("gc_realloc(%p -> %p)\n", ptr_in, ptr_out); memcpy(ptr_out, ptr_in, n_blocks * BYTES_PER_BLOCK); gc_free(ptr_in); return ptr_out; } #endif // Alternative gc_realloc impl void gc_dump_info(void) { gc_info_t info; gc_info(&info); mp_printf(&mp_plat_print, "GC: total: %u, used: %u, free: %u\n", (uint)info.total, (uint)info.used, (uint)info.free); mp_printf(&mp_plat_print, " No. of 1-blocks: %u, 2-blocks: %u, max blk sz: %u, max free sz: %u\n", (uint)info.num_1block, (uint)info.num_2block, (uint)info.max_block, (uint)info.max_free); } void gc_dump_alloc_table(void) { GC_ENTER(); static const size_t DUMP_BYTES_PER_LINE = 64; #if !EXTENSIVE_HEAP_PROFILING // When comparing heap output we don't want to print the starting // pointer of the heap because it changes from run to run. mp_printf(&mp_plat_print, "GC memory layout; from %p:", MP_STATE_MEM(gc_pool_start)); #endif for (size_t bl = 0; bl < MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB; bl++) { if (bl % DUMP_BYTES_PER_LINE == 0) { // a new line of blocks { // check if this line contains only free blocks size_t bl2 = bl; while (bl2 < MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB && ATB_GET_KIND(bl2) == AT_FREE) { bl2++; } if (bl2 - bl >= 2 * DUMP_BYTES_PER_LINE) { // there are at least 2 lines containing only free blocks, so abbreviate their printing mp_printf(&mp_plat_print, "\n (%u lines all free)", (uint)(bl2 - bl) / DUMP_BYTES_PER_LINE); bl = bl2 & (~(DUMP_BYTES_PER_LINE - 1)); if (bl >= MP_STATE_MEM(gc_alloc_table_byte_len) * BLOCKS_PER_ATB) { // got to end of heap break; } } } // print header for new line of blocks // (the cast to uint32_t is for 16-bit ports) //mp_printf(&mp_plat_print, "\n%05x: ", (uint)(PTR_FROM_BLOCK(bl) & (uint32_t)0xfffff)); mp_printf(&mp_plat_print, "\n%05x: ", (uint)((bl * BYTES_PER_BLOCK) & (uint32_t)0xfffff)); } int c = ' '; switch (ATB_GET_KIND(bl)) { case AT_FREE: c = '.'; break; /* this prints out if the object is reachable from BSS or STACK (for unix only) case AT_HEAD: { c = 'h'; void **ptrs = (void**)(void*)&mp_state_ctx; mp_uint_t len = offsetof(mp_state_ctx_t, vm.stack_top) / sizeof(mp_uint_t); for (mp_uint_t i = 0; i < len; i++) { mp_uint_t ptr = (mp_uint_t)ptrs[i]; if (VERIFY_PTR(ptr) && BLOCK_FROM_PTR(ptr) == bl) { c = 'B'; break; } } if (c == 'h') { ptrs = (void**)&c; len = ((mp_uint_t)MP_STATE_THREAD(stack_top) - (mp_uint_t)&c) / sizeof(mp_uint_t); for (mp_uint_t i = 0; i < len; i++) { mp_uint_t ptr = (mp_uint_t)ptrs[i]; if (VERIFY_PTR(ptr) && BLOCK_FROM_PTR(ptr) == bl) { c = 'S'; break; } } } break; } */ /* this prints the uPy object type of the head block */ case AT_HEAD: { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wcast-align" void **ptr = (void**)(MP_STATE_MEM(gc_pool_start) + bl * BYTES_PER_BLOCK); #pragma GCC diagnostic pop if (*ptr == &mp_type_tuple) { c = 'T'; } else if (*ptr == &mp_type_list) { c = 'L'; } else if (*ptr == &mp_type_dict) { c = 'D'; } else if (*ptr == &mp_type_str || *ptr == &mp_type_bytes) { c = 'S'; } #if MICROPY_PY_BUILTINS_BYTEARRAY else if (*ptr == &mp_type_bytearray) { c = 'A'; } #endif #if MICROPY_PY_ARRAY else if (*ptr == &mp_type_array) { c = 'A'; } #endif #if MICROPY_PY_BUILTINS_FLOAT else if (*ptr == &mp_type_float) { c = 'F'; } #endif else if (*ptr == &mp_type_fun_bc) { c = 'B'; } else if (*ptr == &mp_type_module) { c = 'M'; } else { c = 'h'; #if 0 // This code prints "Q" for qstr-pool data, and "q" for qstr-str // data. It can be useful to see how qstrs are being allocated, // but is disabled by default because it is very slow. for (qstr_pool_t *pool = MP_STATE_VM(last_pool); c == 'h' && pool != NULL; pool = pool->prev) { if ((qstr_pool_t*)ptr == pool) { c = 'Q'; break; } for (const byte **q = pool->qstrs, **q_top = pool->qstrs + pool->len; q < q_top; q++) { if ((const byte*)ptr == *q) { c = 'q'; break; } } } #endif } break; } case AT_TAIL: c = '='; break; case AT_MARK: c = 'm'; break; } mp_printf(&mp_plat_print, "%c", c); } mp_print_str(&mp_plat_print, "\n"); GC_EXIT(); } #if DEBUG_PRINT void gc_test(void) { mp_uint_t len = 500; mp_uint_t *heap = malloc(len); gc_init(heap, heap + len / sizeof(mp_uint_t)); void *ptrs[100]; { mp_uint_t **p = gc_alloc(16, false); p[0] = gc_alloc(64, false); p[1] = gc_alloc(1, false); p[2] = gc_alloc(1, false); p[3] = gc_alloc(1, false); mp_uint_t ***p2 = gc_alloc(16, false); p2[0] = p; p2[1] = p; ptrs[0] = p2; } for (int i = 0; i < 25; i+=2) { mp_uint_t *p = gc_alloc(i, false); printf("p=%p\n", p); if (i & 3) { //ptrs[i] = p; } } printf("Before GC:\n"); gc_dump_alloc_table(); printf("Starting GC...\n"); gc_collect_start(); gc_collect_root(ptrs, sizeof(ptrs) / sizeof(void*)); gc_collect_end(); printf("After GC:\n"); gc_dump_alloc_table(); } #endif #endif // MICROPY_ENABLE_GC