// force the freeing of a piece of memory
// TODO: freeing here does not call finaliser
void gc_free(void *ptr) {
if (MP_STATE_MEM(gc_lock_depth) > 0) {
// TODO how to deal with this error?
return;
}
DEBUG_printf("gc_free(%p)\n", ptr);
if (VERIFY_PTR(ptr)) {
size_t block = BLOCK_FROM_PTR(ptr);
if (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_last_free_atb_index)) {
MP_STATE_MEM(gc_last_free_atb_index) = block / BLOCKS_PER_ATB;
}
// free head and all of its tail blocks
do {
ATB_ANY_TO_FREE(block);
block += 1;
} while (ATB_GET_KIND(block) == AT_TAIL);
#if EXTENSIVE_HEAP_PROFILING
gc_dump_alloc_table();
#endif
} else {
assert(!"bad free");
}
} else if (ptr != NULL) {
assert(!"bad free");
}
}
// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
if (gc_lock_depth > 0) {
// TODO how to deal with this error?
return;
}
mp_uint_t ptr = (mp_uint_t)ptr_in;
DEBUG_printf("gc_free(%p)\n", ptr);
if (VERIFY_PTR(ptr)) {
mp_uint_t block = BLOCK_FROM_PTR(ptr);
if (ATB_GET_KIND(block) == AT_HEAD) {
// set the last_free pointer to this block if it's earlier in the heap
if (block / BLOCKS_PER_ATB < gc_last_free_atb_index) {
gc_last_free_atb_index = block / BLOCKS_PER_ATB;
}
// free head and all of its tail blocks
do {
ATB_ANY_TO_FREE(block);
block += 1;
} while (ATB_GET_KIND(block) == AT_TAIL);
#if EXTENSIVE_HEAP_PROFILING
gc_dump_alloc_table();
#endif
}
}
}
// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
machine_uint_t ptr = (machine_uint_t)ptr_in;
if (VERIFY_PTR(ptr)) {
machine_uint_t block = BLOCK_FROM_PTR(ptr);
if (ATB_GET_KIND(block) == AT_HEAD) {
// free head and all of its tail blocks
do {
ATB_ANY_TO_FREE(block);
block += 1;
} while (ATB_GET_KIND(block) == AT_TAIL);
}
}
}
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);
}
}
}
}
size_t gc_nbytes(const void *ptr) {
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);
return n_blocks * BYTES_PER_BLOCK;
}
}
// invalid pointer
return 0;
}
// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
if (gc_lock_depth > 0) {
// TODO how to deal with this error?
return;
}
machine_uint_t ptr = (machine_uint_t)ptr_in;
if (VERIFY_PTR(ptr)) {
machine_uint_t block = BLOCK_FROM_PTR(ptr);
if (ATB_GET_KIND(block) == AT_HEAD) {
// free head and all of its tail blocks
do {
ATB_ANY_TO_FREE(block);
block += 1;
} while (ATB_GET_KIND(block) == AT_TAIL);
}
}
}
// 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];
}
}
// old, simple realloc that didn't expand memory in place
void *gc_realloc(void *ptr, machine_uint_t n_bytes) {
machine_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((machine_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;
}
}
void *gc_realloc(void *ptr_in, machine_uint_t n_bytes) {
if (gc_lock_depth > 0) {
return NULL;
}
// check for pure allocation
if (ptr_in == NULL) {
return gc_alloc(n_bytes, false);
}
machine_uint_t ptr = (machine_uint_t)ptr_in;
// sanity check the ptr
if (!VERIFY_PTR(ptr)) {
return NULL;
}
// get first block
machine_uint_t block = BLOCK_FROM_PTR(ptr);
// sanity check the ptr is pointing to the head of a block
if (ATB_GET_KIND(block) != AT_HEAD) {
return NULL;
}
// compute number of new blocks that are requested
machine_uint_t new_blocks = (n_bytes + BYTES_PER_BLOCK - 1) / BYTES_PER_BLOCK;
// get the number of consecutive tail blocks and
// the number of free blocks after last tail block
// stop if we reach (or are at) end of heap
machine_uint_t n_free = 0;
machine_uint_t n_blocks = 1; // counting HEAD block
machine_uint_t max_block = gc_alloc_table_byte_len * BLOCKS_PER_ATB;
while (block + n_blocks + n_free < max_block) {
if (n_blocks + n_free >= new_blocks) {
// stop as soon as we find enough blocks for n_bytes
break;
}
byte block_type = ATB_GET_KIND(block + n_blocks + n_free);
switch (block_type) {
case AT_FREE: n_free++; continue;
case AT_TAIL: n_blocks++; continue;
case AT_MARK: assert(0);
}
break;
}
// return original ptr if it already has the requested number of blocks
if (new_blocks == n_blocks) {
return ptr_in;
}
// check if we can shrink the allocated area
if (new_blocks < n_blocks) {
// free unneeded tail blocks
for (machine_uint_t bl = block + new_blocks; ATB_GET_KIND(bl) == AT_TAIL; bl++) {
ATB_ANY_TO_FREE(bl);
}
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 (machine_uint_t bl = block + n_blocks; bl < block + new_blocks; bl++) {
assert(ATB_GET_KIND(bl) == AT_FREE);
ATB_FREE_TO_TAIL(bl);
}
// 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);
return ptr_in;
}
// can't resize inplace; try to find a new contiguous chain
void *ptr_out = gc_alloc(n_bytes,
#if MICROPY_ENABLE_FINALISER
FTB_GET(block)
#else
false
#endif
);
// 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;
}
void *gc_realloc(void *ptr_in, size_t n_bytes, bool allow_move) {
if (MP_STATE_MEM(gc_lock_depth) > 0) {
return NULL;
}
// check for pure allocation
if (ptr_in == NULL) {
return gc_alloc(n_bytes, false);
}
// check for pure free
if (n_bytes == 0) {
gc_free(ptr_in);
return NULL;
}
void *ptr = ptr_in;
// sanity check the ptr
if (!VERIFY_PTR(ptr)) {
return NULL;
}
// get first block
size_t block = BLOCK_FROM_PTR(ptr);
// sanity check the ptr is pointing to the head of a block
if (ATB_GET_KIND(block) != AT_HEAD) {
return NULL;
}
// 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) {
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_last_free_atb_index)) {
MP_STATE_MEM(gc_last_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB;
}
#if EXTENSIVE_HEAP_PROFILING
gc_dump_alloc_table();
#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);
}
// zero out the bytes of the newly allocated blocks (see comment above in gc_alloc)
memset((byte*)ptr_in + n_blocks * BYTES_PER_BLOCK, 0, (new_blocks - n_blocks) * BYTES_PER_BLOCK);
#if EXTENSIVE_HEAP_PROFILING
gc_dump_alloc_table();
#endif
return ptr_in;
}
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,
#if MICROPY_ENABLE_FINALISER
FTB_GET(block)
#else
false
#endif
);
// 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;
}
