sljitExecAllocator.c [plain text]
#define CHUNK_SIZE 0x10000
#ifdef _WIN32
static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
{
return VirtualAlloc(NULL, size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
}
static SLJIT_INLINE void free_chunk(void* chunk, sljit_uw size)
{
SLJIT_UNUSED_ARG(size);
VirtualFree(chunk, 0, MEM_RELEASE);
}
#else
static SLJIT_INLINE void* alloc_chunk(sljit_uw size)
{
void* retval;
#ifdef MAP_ANON
retval = mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANON, -1, 0);
#else
if (dev_zero < 0) {
if (open_dev_zero())
return NULL;
}
retval = mmap(NULL, size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, dev_zero, 0);
#endif
return (retval != MAP_FAILED) ? retval : NULL;
}
static SLJIT_INLINE void free_chunk(void* chunk, sljit_uw size)
{
munmap(chunk, size);
}
#endif
#define CHUNK_MASK (~(CHUNK_SIZE - 1))
struct block_header {
sljit_uw size;
sljit_uw prev_size;
};
struct free_block {
struct block_header header;
struct free_block *next;
struct free_block *prev;
sljit_uw size;
};
#define AS_BLOCK_HEADER(base, offset) \
((struct block_header*)(((sljit_ub*)base) + offset))
#define AS_FREE_BLOCK(base, offset) \
((struct free_block*)(((sljit_ub*)base) + offset))
#define MEM_START(base) ((void*)(((sljit_ub*)base) + sizeof(struct block_header)))
#define ALIGN_SIZE(size) (((size) + sizeof(struct block_header) + 7) & ~7)
static struct free_block* free_blocks;
static sljit_uw allocated_size;
static sljit_uw total_size;
static SLJIT_INLINE void sljit_insert_free_block(struct free_block *free_block, sljit_uw size)
{
free_block->header.size = 0;
free_block->size = size;
free_block->next = free_blocks;
free_block->prev = 0;
if (free_blocks)
free_blocks->prev = free_block;
free_blocks = free_block;
}
static SLJIT_INLINE void sljit_remove_free_block(struct free_block *free_block)
{
if (free_block->next)
free_block->next->prev = free_block->prev;
if (free_block->prev)
free_block->prev->next = free_block->next;
else {
SLJIT_ASSERT(free_blocks == free_block);
free_blocks = free_block->next;
}
}
SLJIT_API_FUNC_ATTRIBUTE void* sljit_malloc_exec(sljit_uw size)
{
struct block_header *header;
struct block_header *next_header;
struct free_block *free_block;
sljit_uw chunk_size;
allocator_grab_lock();
if (size < sizeof(struct free_block))
size = sizeof(struct free_block);
size = ALIGN_SIZE(size);
free_block = free_blocks;
while (free_block) {
if (free_block->size >= size) {
chunk_size = free_block->size;
if (chunk_size > size + 64) {
chunk_size -= size;
free_block->size = chunk_size;
header = AS_BLOCK_HEADER(free_block, chunk_size);
header->prev_size = chunk_size;
AS_BLOCK_HEADER(header, size)->prev_size = size;
}
else {
sljit_remove_free_block(free_block);
header = (struct block_header*)free_block;
size = chunk_size;
}
allocated_size += size;
header->size = size;
allocator_release_lock();
return MEM_START(header);
}
free_block = free_block->next;
}
chunk_size = (size + sizeof(struct block_header) + CHUNK_SIZE - 1) & CHUNK_MASK;
header = (struct block_header*)alloc_chunk(chunk_size);
if (!header) {
allocator_release_lock();
return NULL;
}
chunk_size -= sizeof(struct block_header);
total_size += chunk_size;
header->prev_size = 0;
if (chunk_size > size + 64) {
allocated_size += size;
header->size = size;
chunk_size -= size;
free_block = AS_FREE_BLOCK(header, size);
free_block->header.prev_size = size;
sljit_insert_free_block(free_block, chunk_size);
next_header = AS_BLOCK_HEADER(free_block, chunk_size);
}
else {
allocated_size += chunk_size;
header->size = chunk_size;
next_header = AS_BLOCK_HEADER(header, chunk_size);
}
next_header->size = 1;
next_header->prev_size = chunk_size;
allocator_release_lock();
return MEM_START(header);
}
SLJIT_API_FUNC_ATTRIBUTE void sljit_free_exec(void* ptr)
{
struct block_header *header;
struct free_block* free_block;
allocator_grab_lock();
header = AS_BLOCK_HEADER(ptr, -(sljit_sw)sizeof(struct block_header));
allocated_size -= header->size;
free_block = AS_FREE_BLOCK(header, -(sljit_sw)header->prev_size);
if (SLJIT_UNLIKELY(!free_block->header.size)) {
free_block->size += header->size;
header = AS_BLOCK_HEADER(free_block, free_block->size);
header->prev_size = free_block->size;
}
else {
free_block = (struct free_block*)header;
sljit_insert_free_block(free_block, header->size);
}
header = AS_BLOCK_HEADER(free_block, free_block->size);
if (SLJIT_UNLIKELY(!header->size)) {
free_block->size += ((struct free_block*)header)->size;
sljit_remove_free_block((struct free_block*)header);
header = AS_BLOCK_HEADER(free_block, free_block->size);
header->prev_size = free_block->size;
}
if (SLJIT_UNLIKELY(!free_block->header.prev_size && header->size == 1)) {
if (total_size - free_block->size > (allocated_size * 3 / 2)) {
total_size -= free_block->size;
sljit_remove_free_block(free_block);
free_chunk(free_block, free_block->size + sizeof(struct block_header));
}
}
allocator_release_lock();
}
SLJIT_API_FUNC_ATTRIBUTE void sljit_free_unused_memory_exec(void)
{
struct free_block* free_block;
struct free_block* next_free_block;
allocator_grab_lock();
free_block = free_blocks;
while (free_block) {
next_free_block = free_block->next;
if (!free_block->header.prev_size &&
AS_BLOCK_HEADER(free_block, free_block->size)->size == 1) {
total_size -= free_block->size;
sljit_remove_free_block(free_block);
free_chunk(free_block, free_block->size + sizeof(struct block_header));
}
free_block = next_free_block;
}
SLJIT_ASSERT((total_size && free_blocks) || (!total_size && !free_blocks));
allocator_release_lock();
}