122 lines
2.9 KiB
C++
122 lines
2.9 KiB
C++
#define align_pow2(x, b) (((x) + (b) - 1) & ( ~((b) - 1)))
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#define SLLStackPush_N(f,n,next) ((n)->next=(f), (f)=(n))
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#define SLLStackPop_N(f,next) ((f)=(f)->next)
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#ifdef DEBUG
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#define asan_poison_memory_region(mem, cmt) __asan_poison_memory_region(mem, cmt)
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#define asan_unpoison_memory_region(mem, cmt) __asan_unpoison_memory_region(mem, cmt)
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#else
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#define asan_poison_memory_region(mem, cmt)
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#define asan_unpoison_memory_region(mem, cmt)
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#endif
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void *os_reserve(u64 size)
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{
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return mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
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}
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void os_release(void *mem, u64 size)
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{
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munmap(mem, size);
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}
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b32x os_commit(void *addr, u64 size)
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{
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return mprotect(addr, size, PROT_READ|PROT_WRITE) == 0;
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}
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// init_res: initial reserved size
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// init_cmt: initial committed size
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Arena *arena_alloc_sized(u64 init_res, u64 init_cmt)
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{
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assert(ARENA_HEADER_SIZE < init_cmt && init_cmt <= init_res);
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u64 page_size = getpagesize();
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u64 res = align_pow2(init_res, page_size);
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u64 cmt = align_pow2(init_cmt, page_size);
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// reserve memory
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void *mem = os_reserve(res);
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if (!os_commit(mem, cmt)) {
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munmap(mem, init_res);
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}
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Arena *arena = (Arena *)mem;
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if (arena) {
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asan_poison_memory_region(mem, cmt);
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asan_unpoison_memory_region(mem, ARENA_HEADER_SIZE);
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arena->cur = arena;
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arena->pos = ARENA_HEADER_SIZE;
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arena->cmt = cmt;
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arena->res = res;
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arena->align = 8;
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}
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return arena;
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}
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Arena *arena_alloc()
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{
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return arena_alloc_sized(ARENA_RESERVE_SIZE, ARENA_COMMIT_SIZE);
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}
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void arena_release(Arena *arena)
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{
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for (Arena *node = arena->cur, *prev = 0; node; node = prev) {
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prev = node->prev;
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os_release(node, node->res);
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}
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}
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u64 arena_huge_push_threshold()
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{
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u64 res = ARENA_RESERVE_SIZE;
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u64 threshold = (res - ARENA_HEADER_SIZE) / 2 + 1;
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return threshold;
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}
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void *arena_push_impl(Arena *arena, u64 size)
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{
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Arena *cur = arena->cur;
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u64 pos_mem = align_pow2(cur->pos, arena->align);
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u64 pos_new = pos_mem + size;
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if (cur->res < pos_new) {
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Arena *new_block;
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if (size < arena_huge_push_threshold()) {
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new_block = arena_alloc();
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} else {
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u64 new_block_size = size + ARENA_HEADER_SIZE;
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new_block = arena_alloc_sized(new_block_size, new_block_size);
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}
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if (new_block) {
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new_block->base_pos = cur->base_pos + cur->res;
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SLLStackPush_N(arena->cur, new_block, prev);
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cur = new_block;
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pos_mem = align_pow2(cur->pos, cur->align);
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pos_new = pos_mem + size;
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}
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}
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if (cur->cmt < pos_new) {
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u64 cmt_new_aligned = align_pow2(pos_new, ARENA_COMMIT_SIZE);
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u64 cmt_new_clamped = std::min(cmt_new_aligned, cur->res);
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u64 cmt_new_size = cmt_new_clamped - cur->cmt;
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b32x is_cmt_ok = os_commit((u8*)cur + cur->cmt, cmt_new_size);
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if (is_cmt_ok)
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cur->cmt = cmt_new_clamped;
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}
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void *mem = 0;
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if (cur->cmt >= pos_new) {
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mem = (u8*)cur + pos_mem;
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cur->pos = pos_new;
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asan_unpoison_memory_region(mem, size);
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}
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return mem;
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}
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