			#include "gc.h"
			#include "arena.h"
			#include "internal.h"
			#include "common.h"
			#include "sugar.h"
			#include "silver/engine.h"

			#include <string.h>
			#include <stdlib.h>
			#include <stdio.h>
			#include <time.h>
			#include <setjmp.h>

			#if defined(__has_feature)
			#if __has_feature(address_sanitizer)
			#include <sanitizer/asan_interface.h>
			#define ANT_HAS_ASAN 1
			#endif
			#endif

			#ifndef ANT_HAS_ASAN
			#define ANT_HAS_ASAN 0
			#endif

			#ifdef _WIN32
			#define WIN32_LEAN_AND_MEAN
			#include <windows.h>
			static inline void *gc_mmap(size_t size) {
			return VirtualAlloc(NULL, size, MEM_COMMIT \| MEM_RESERVE, PAGE_READWRITE);
			}
			static inline void gc_munmap(void *ptr, size_t size) {
			VirtualFree(ptr, 0, MEM_RELEASE);
			}
			#else
			#include <sys/mman.h>
			static inline void *gc_mmap(size_t size) {
			void *p = mmap(NULL, size, PROT_READ \| PROT_WRITE, MAP_PRIVATE \| MAP_ANON, -1, 0);
			return (p == MAP_FAILED) ? NULL : p;
			}
			static inline void gc_munmap(void *ptr, size_t size) {
			munmap(ptr, size);
			}
			#endif

			#define MCO_API extern
			#include "minicoro.h"

			uint32_t gc_epoch_counter;
			static uint8_t *gc_scratch_buf = NULL;

			static size_t gc_scratch_size = 0;
			static time_t gc_last_run_time = 0;

			static bool gc_throttled = false;
			void js_gc_throttle(bool enabled) { gc_throttled = enabled; }

			typedef struct {
			jsoff_t *old_offs;
			jsoff_t *new_offs;
			size_t count;
			size_t capacity;
			size_t mask;
			} gc_forward_table_t;

			typedef struct {
			jsoff_t *items;
			size_t count;
			size_t capacity;
			} gc_work_queue_t;

			typedef struct {
			ant_t *js;
			uint8_t *new_mem;
			uint8_t *mark_bits;
			gc_forward_table_t fwd;
			gc_work_queue_t work;
			jsoff_t new_brk;
			jsoff_t new_size;
			bool failed;
			} gc_ctx_t;

			static jsval_t gc_update_val(gc_ctx_t *ctx, jsval_t val);
			static jsval_t gc_apply_val(gc_ctx_t *ctx, jsval_t val);

			/* inlined helpers from ant.c */
			static inline bool gc_func_const_count_sane(int n) {
			return n >= 0 && n <= (1 << 20);
			}

			static inline bool gc_upvalue_is_closed(const sv_upvalue_t *uv) {
			return uv && uv->location == &uv->closed;
			}

			static inline bool gc_is_tagged(jsval_t v) {
			return v > NANBOX_PREFIX;
			}

			static inline uint8_t gc_vtype(jsval_t v) {
			return gc_is_tagged(v) ? ((v >> NANBOX_TYPE_SHIFT) & NANBOX_TYPE_MASK) : 255;
			}

			static inline size_t gc_vdata(jsval_t v) {
			return (size_t)(v & NANBOX_DATA_MASK);
			}

			static inline jsval_t gc_mkval(uint8_t type, uint64_t data) {
			return NANBOX_PREFIX
			\| ((jsval_t)(type & NANBOX_TYPE_MASK) << NANBOX_TYPE_SHIFT)
			\| (data & NANBOX_DATA_MASK);
			}

			static inline void mark_set(gc_ctx_t *ctx, jsoff_t off) {
			jsoff_t idx = off >> 3;
			ctx->mark_bits[idx >> 3] \|= (1 << (idx & 7));
			}

			static inline size_t next_pow2(size_t n) {
			n--;
			n \|= n >> 1; n \|= n >> 2; n \|= n >> 4;
			n \|= n >> 8; n \|= n >> 16;
			#if SIZE_MAX > 0xFFFFFFFF
			n \|= n >> 32;
			#endif
			return n + 1;
			}

			static void gc_update_func_constants(gc_ctx_t ctx, sv_func_t func, int depth) {
			if (!func \|\| depth > 1024) return;
			if (func->gc_epoch == gc_epoch_counter) return;

			func->gc_epoch = gc_epoch_counter;
			if (!func->constants \|\| !gc_func_const_count_sane(func->const_count)) return;

			for (int i = 0; i < func->const_count; i++) {
			jsval_t c = func->constants[i];

			if (vtype(c) == T_CFUNC) {
			sv_func_t child = (sv_func_t )(uintptr_t)vdata(c);
			gc_update_func_constants(ctx, child, depth + 1);
			continue;
			}

			func->constants[i] = gc_update_val(ctx, c);
			}
			}

			static inline void gc_update_closure(gc_ctx_t ctx, sv_closure_t closure) {
			if (!closure) return;
			if (closure->gc_epoch == gc_epoch_counter) return;

			closure->gc_epoch = gc_epoch_counter;
			closure->func_obj = gc_update_val(ctx, closure->func_obj);
			closure->bound_this = gc_update_val(ctx, closure->bound_this);

			if (!closure->func) return;
			gc_update_func_constants(ctx, closure->func, 0);

			if (!closure->upvalues) return;
			int n = closure->func->upvalue_count;
			if (n <= 0 \|\| n > (int)UINT16_MAX) return;

			for (int i = 0; i < n; i++) {
			sv_upvalue_t *uv = closure->upvalues[i];
			if (!gc_upvalue_is_closed(uv)) continue;
			if (uv->gc_epoch == gc_epoch_counter) continue;
			uv->gc_epoch = gc_epoch_counter;
			uv->closed = gc_update_val(ctx, uv->closed);
			}
			}

			static bool fwd_init(gc_forward_table_t *fwd, size_t estimated) {
			size_t cap = next_pow2(estimated < 64 ? 64 : estimated);
			size_t size = cap * sizeof(jsoff_t);

			fwd->old_offs = (jsoff_t *)gc_mmap(size);
			fwd->new_offs = (jsoff_t *)gc_mmap(size);

			if (!fwd->old_offs \|\| !fwd->new_offs) {
			if (fwd->old_offs) gc_munmap(fwd->old_offs, size);
			if (fwd->new_offs) gc_munmap(fwd->new_offs, size);
			return false;
			}

			for (size_t i = 0; i < cap; i++) fwd->old_offs[i] = FWD_EMPTY;

			fwd->count = 0;
			fwd->capacity = cap;
			fwd->mask = cap - 1;

			return true;
			}

			static bool fwd_grow(gc_forward_table_t *fwd) {
			size_t new_cap = fwd->capacity * 2;
			size_t new_mask = new_cap - 1;
			size_t new_size = new_cap * sizeof(jsoff_t);
			size_t old_size = fwd->capacity * sizeof(jsoff_t);

			jsoff_t new_old = (jsoff_t )gc_mmap(new_size);
			jsoff_t new_new = (jsoff_t )gc_mmap(new_size);

			if (!new_old \|\| !new_new) {
			if (new_old) gc_munmap(new_old, new_size);
			if (new_new) gc_munmap(new_new, new_size);
			return false;
			}

			for (size_t i = 0; i < new_cap; i++) new_old[i] = FWD_EMPTY;

			for (size_t i = 0; i < fwd->capacity; i++) {
			jsoff_t key = fwd->old_offs[i];
			if (key == FWD_EMPTY \|\| key == FWD_TOMBSTONE) continue;
			size_t h = (key >> 3) & new_mask;
			while (new_old[h] != FWD_EMPTY) h = (h + 1) & new_mask;
			new_old[h] = key;
			new_new[h] = fwd->new_offs[i];
			}

			gc_munmap(fwd->old_offs, old_size);
			gc_munmap(fwd->new_offs, old_size);

			fwd->old_offs = new_old;
			fwd->new_offs = new_new;
			fwd->capacity = new_cap;
			fwd->mask = new_mask;

			return true;
			}

			static inline bool fwd_add(gc_forward_table_t *fwd, jsoff_t old_off, jsoff_t new_off) {
			if (fwd->count * 100 >= fwd->capacity * GC_FWD_LOAD_FACTOR) {
			if (!fwd_grow(fwd)) return false;
			}

			size_t h = (old_off >> 3) & fwd->mask;
			while (fwd->old_offs[h] != FWD_EMPTY && fwd->old_offs[h] != FWD_TOMBSTONE) {
			if (fwd->old_offs[h] == old_off) {
			fwd->new_offs[h] = new_off;
			return true;
			}
			h = (h + 1) & fwd->mask;
			}

			fwd->old_offs[h] = old_off;
			fwd->new_offs[h] = new_off;
			fwd->count++;

			return true;
			}

			static inline jsoff_t fwd_lookup(gc_forward_table_t *fwd, jsoff_t old_off) {
			size_t h = (old_off >> 3) & fwd->mask;
			for (size_t i = 0; i < fwd->capacity; i++) {
			jsoff_t key = fwd->old_offs[h];
			if (key == FWD_EMPTY) return (jsoff_t)~0;
			if (key == old_off) return fwd->new_offs[h];
			h = (h + 1) & fwd->mask;
			}
			return (jsoff_t)~0;
			}

			static void fwd_free(gc_forward_table_t *fwd) {
			size_t size = fwd->capacity * sizeof(jsoff_t);
			if (fwd->old_offs) gc_munmap(fwd->old_offs, size);
			if (fwd->new_offs) gc_munmap(fwd->new_offs, size);

			fwd->old_offs = NULL;
			fwd->new_offs = NULL;
			fwd->count = 0;
			fwd->capacity = 0;
			}

			static bool work_init(gc_work_queue_t *work, size_t initial) {
			size_t size = initial * sizeof(jsoff_t);
			work->items = (jsoff_t *)gc_mmap(size);
			if (!work->items) return false;
			work->count = 0;
			work->capacity = initial;
			return true;
			}

			static inline bool work_push(gc_work_queue_t *work, jsoff_t off) {
			if (work->count >= work->capacity) {
			size_t new_cap = work->capacity * 2;
			size_t new_size = new_cap * sizeof(jsoff_t);
			size_t old_size = work->capacity * sizeof(jsoff_t);

			jsoff_t new_items = (jsoff_t )gc_mmap(new_size);
			if (!new_items) return false;

			memcpy(new_items, work->items, work->count * sizeof(jsoff_t));
			gc_munmap(work->items, old_size);

			work->items = new_items;
			work->capacity = new_cap;
			}

			work->items[work->count++] = off;
			return true;
			}

			static inline jsoff_t work_pop(gc_work_queue_t *work) {
			if (work->count == 0) return (jsoff_t)~0;
			return work->items[--work->count];
			}

			static void work_free(gc_work_queue_t *work) {
			size_t size = work->capacity * sizeof(jsoff_t);
			if (work->items) gc_munmap(work->items, size);

			work->items = NULL;
			work->count = 0;
			work->capacity = 0;
			}

			static inline jsoff_t gc_loadoff(uint8_t *mem, jsoff_t off) {
			jsoff_t val;
			memcpy(&val, &mem[off], sizeof(val));
			return val;
			}

			static inline jsval_t gc_loadval(uint8_t *mem, jsoff_t off) {
			jsval_t val;
			memcpy(&val, &mem[off], sizeof(val));
			return val;
			}

			static inline void gc_saveoff(uint8_t *mem, jsoff_t off, jsoff_t val) {
			memcpy(&mem[off], &val, sizeof(val));
			}

			static inline void gc_saveval(uint8_t *mem, jsoff_t off, jsval_t val) {
			memcpy(&mem[off], &val, sizeof(val));
			}

			static jsoff_t gc_alloc(gc_ctx_t *ctx, size_t size) {
			size = (size + 7) / 8 * 8;
			if (ctx->new_brk + size > ctx->new_size) {
			ctx->failed = true;
			return (jsoff_t)~0;
			}
			jsoff_t off = ctx->new_brk;
			ctx->new_brk += (jsoff_t)size;
			return off;
			}

			static jsoff_t gc_copy_string(gc_ctx_t *ctx, jsoff_t old_off) {
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return new_off;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			if ((header & 3) != T_STR) return old_off;

			bool is_rope_str = (header & ROPE_FLAG) != 0;
			jsoff_t size;

			if (is_rope_str) {
			size = sizeof(rope_node_t);
			} else size = esize(header);

			if (size == (jsoff_t)~0) return old_off;

			new_off = gc_alloc(ctx, size);
			if (new_off == (jsoff_t)~0) return old_off;

			memcpy(&ctx->new_mem[new_off], &ctx->js->mem[old_off], size);
			if (!fwd_add(&ctx->fwd, old_off, new_off)) ctx->failed = true;
			mark_set(ctx, old_off);

			if (is_rope_str) {
			jsval_t left, right, cached;
			memcpy(&left, &ctx->js->mem[old_off + offsetof(rope_node_t, left)], sizeof(jsval_t));
			memcpy(&right, &ctx->js->mem[old_off + offsetof(rope_node_t, right)], sizeof(jsval_t));
			memcpy(&cached, &ctx->js->mem[old_off + offsetof(rope_node_t, cached)], sizeof(jsval_t));

			jsval_t new_left = gc_update_val(ctx, left);
			jsval_t new_right = gc_update_val(ctx, right);
			jsval_t new_cached = gc_update_val(ctx, cached);

			memcpy(&ctx->new_mem[new_off + offsetof(rope_node_t, left)], &new_left, sizeof(jsval_t));
			memcpy(&ctx->new_mem[new_off + offsetof(rope_node_t, right)], &new_right, sizeof(jsval_t));
			memcpy(&ctx->new_mem[new_off + offsetof(rope_node_t, cached)], &new_cached, sizeof(jsval_t));
			}

			return new_off;
			}

			static jsoff_t gc_copy_bigint(gc_ctx_t *ctx, jsoff_t old_off) {
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return new_off;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			size_t total = (header >> 4) + sizeof(jsoff_t);
			total = (total + 7) / 8 * 8;

			new_off = gc_alloc(ctx, total);
			if (new_off == (jsoff_t)~0) return old_off;

			memcpy(&ctx->new_mem[new_off], &ctx->js->mem[old_off], total);
			if (!fwd_add(&ctx->fwd, old_off, new_off)) ctx->failed = true;
			mark_set(ctx, old_off);

			return new_off;
			}

			static jsoff_t gc_copy_symbol(gc_ctx_t *ctx, jsoff_t old_off) {
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return new_off;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			size_t total = (header >> GC_SYM_HEADER_SHIFT) + sizeof(jsoff_t);
			total = (total + 7) / 8 * 8;

			new_off = gc_alloc(ctx, total);
			if (new_off == (jsoff_t)~0) return old_off;

			memcpy(&ctx->new_mem[new_off], &ctx->js->mem[old_off], total);
			if (!fwd_add(&ctx->fwd, old_off, new_off)) ctx->failed = true;
			mark_set(ctx, old_off);

			return new_off;
			}

			static jsoff_t gc_reserve_object(gc_ctx_t *ctx, jsoff_t old_off) {
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return new_off;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			if ((header & 3) != T_OBJ) return old_off;

			jsoff_t size = esize(header);
			if (size == (jsoff_t)~0) return old_off;

			new_off = gc_alloc(ctx, size);
			if (new_off == (jsoff_t)~0) return old_off;

			memcpy(&ctx->new_mem[new_off], &ctx->js->mem[old_off], size);
			if (!fwd_add(&ctx->fwd, old_off, new_off)) ctx->failed = true;
			mark_set(ctx, old_off);
			if (!work_push(&ctx->work, old_off)) ctx->failed = true;

			return new_off;
			}

			static jsoff_t gc_reserve_prop(gc_ctx_t *ctx, jsoff_t old_off) {
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return new_off;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			if ((header & 3) != T_PROP) return old_off;

			jsoff_t size = esize(header);
			if (size == (jsoff_t)~0) return old_off;

			new_off = gc_alloc(ctx, size);
			if (new_off == (jsoff_t)~0) return old_off;

			memcpy(&ctx->new_mem[new_off], &ctx->js->mem[old_off], size);
			if (!fwd_add(&ctx->fwd, old_off, new_off)) ctx->failed = true;
			mark_set(ctx, old_off);
			if (!work_push(&ctx->work, old_off)) ctx->failed = true;

			return new_off;
			}

			static void gc_process_prop(gc_ctx_t *ctx, jsoff_t old_off) {
			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off == (jsoff_t)~0) return;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			jsoff_t next_prop = header & ~(3ULL \| FLAGMASK);

			if (next_prop != 0 && next_prop < ctx->js->brk) {
			jsoff_t new_next = gc_reserve_prop(ctx, next_prop);
			jsoff_t new_header = (new_next & ~3ULL) \| (header & (3ULL \| FLAGMASK));
			gc_saveoff(ctx->new_mem, new_off, new_header);
			}

			bool is_slot = (header & SLOTMASK) != 0;

			if (!is_slot) {
			jsoff_t key_off = gc_loadoff(ctx->js->mem, old_off + sizeof(jsoff_t));
			if (key_off < ctx->js->brk) {
			jsoff_t key_hdr = gc_loadoff(ctx->js->mem, key_off); jsoff_t new_key;
			if ((key_hdr & 3) == T_STR) new_key = gc_copy_string(ctx, key_off);
			else new_key = gc_copy_symbol(ctx, key_off);
			gc_saveoff(ctx->new_mem, new_off + sizeof(jsoff_t), new_key);
			}
			}

			jsval_t val = gc_loadval(ctx->js->mem, old_off + sizeof(jsoff_t) + sizeof(jsoff_t));
			if (!is_slot) goto update_val;

			jsoff_t slot_id = gc_loadoff(ctx->js->mem, old_off + sizeof(jsoff_t));
			if (slot_id != (jsoff_t)SLOT_DENSE_BUF) goto update_val;

			jsoff_t old_doff = (jsoff_t)tod(val);
			if (old_doff == 0 \|\| old_doff >= ctx->js->brk) goto update_val;

			jsoff_t cap = gc_loadoff(ctx->js->mem, old_doff);
			jsoff_t len = gc_loadoff(ctx->js->mem, old_doff + sizeof(jsoff_t));
			jsoff_t buf_size = (jsoff_t)(sizeof(jsoff_t) * 2 + sizeof(jsval_t) * cap);
			jsoff_t new_doff = gc_alloc(ctx, buf_size);
			if (new_doff == (jsoff_t)~0) return;

			memcpy(&ctx->new_mem[new_doff], &ctx->js->mem[old_doff], buf_size);
			for (jsoff_t i = 0; i < len; i++) {
			jsoff_t voff = new_doff + (jsoff_t)(sizeof(jsoff_t) * 2 + sizeof(jsval_t) * i);
			jsval_t v = gc_loadval(ctx->new_mem, voff);
			if (v != T_EMPTY) {
			jsval_t nv = gc_update_val(ctx, v);
			gc_saveval(ctx->new_mem, voff, nv);
			}
			}

			gc_saveval(
			ctx->new_mem,
			new_off + sizeof(jsoff_t) + sizeof(jsoff_t),
			tov((double)new_doff)
			); return;

			update_val: {
			jsval_t new_val = gc_update_val(ctx, val);
			gc_saveval(ctx->new_mem, new_off + sizeof(jsoff_t) + sizeof(jsoff_t), new_val);
			}
			}

			static void gc_process_object(gc_ctx_t *ctx, jsoff_t old_off) {
			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off == (jsoff_t)~0) return;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);

			jsoff_t first_prop = header & ~(3ULL \| FLAGMASK);
			if (first_prop != 0 && first_prop < ctx->js->brk) {
			jsoff_t new_first = gc_reserve_prop(ctx, first_prop);
			jsoff_t new_header = (new_first & ~3ULL) \| (header & (3ULL \| FLAGMASK));
			gc_saveoff(ctx->new_mem, new_off, new_header);
			}

			jsoff_t parent_off = gc_loadoff(ctx->js->mem, old_off + sizeof(jsoff_t));
			if (parent_off < ctx->js->brk) {
			jsoff_t new_parent = gc_reserve_object(ctx, parent_off);
			gc_saveoff(ctx->new_mem, new_off + sizeof(jsoff_t), new_parent);
			}

			jsoff_t tail_off = gc_loadoff(ctx->js->mem, old_off + sizeof(jsoff_t) + sizeof(jsoff_t));
			if (tail_off != 0 && tail_off < ctx->js->brk) {
			jsoff_t new_tail = fwd_lookup(&ctx->fwd, tail_off);
			if (new_tail == (jsoff_t)~0) new_tail = gc_reserve_prop(ctx, tail_off);
			gc_saveoff(ctx->new_mem, new_off + sizeof(jsoff_t) + sizeof(jsoff_t), new_tail);
			}
			}

			static void gc_drain_work_queue(gc_ctx_t *ctx) {
			jsoff_t off;
			while ((off = work_pop(&ctx->work)) != (jsoff_t)~0) {
			jsoff_t header = gc_loadoff(ctx->js->mem, off);
			switch (header & 3) {
			case T_OBJ: gc_process_object(ctx, off); break;
			case T_PROP: gc_process_prop(ctx, off); break;
			default: break;
			}
			}
			}

			static jsval_t gc_update_val(gc_ctx_t *ctx, jsval_t val) {
			if (!gc_is_tagged(val)) return val;

			uint8_t type = gc_vtype(val);
			jsoff_t old_off = (jsoff_t)gc_vdata(val);

			switch (type) {
			case T_OBJ:
			case T_ARR:
			case T_PROMISE:
			case T_GENERATOR: {
			if (old_off >= ctx->js->brk) return val;
			jsoff_t new_off = gc_reserve_object(ctx, old_off);
			if (new_off != (jsoff_t)~0) return gc_mkval(type, new_off);
			break;
			}
			case T_STR: {
			if (old_off >= ctx->js->brk) return val;
			jsoff_t new_off = gc_copy_string(ctx, old_off);
			if (new_off != (jsoff_t)~0) return gc_mkval(type, new_off);
			break;
			}
			case T_PROP: {
			if (old_off >= ctx->js->brk) return val;
			jsoff_t new_off = gc_reserve_prop(ctx, old_off);
			if (new_off != (jsoff_t)~0) return gc_mkval(type, new_off);
			break;
			}
			case T_BIGINT: {
			if (old_off >= ctx->js->brk) return val;
			jsoff_t new_off = gc_copy_bigint(ctx, old_off);
			if (new_off != (jsoff_t)~0) return gc_mkval(type, new_off);
			break;
			}
			case T_SYMBOL: {
			if (old_off >= ctx->js->brk) return val;
			jsoff_t new_off = gc_copy_symbol(ctx, old_off);
			if (new_off != (jsoff_t)~0) return gc_mkval(type, new_off);
			break;
			}
			case T_FUNC:
			case T_CLOSURE: {
			gc_update_closure(ctx, (sv_closure_t *)(uintptr_t)gc_vdata(val));
			return val;
			}
			default: break;
			}

			return val;
			}

			static jsoff_t gc_fwd_off_callback(void *ctx_ptr, jsoff_t old_off) {
			gc_ctx_t ctx = (gc_ctx_t )ctx_ptr;
			if (old_off == 0) return 0;
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return new_off;

			static const void *dispatch[] = { &&l_obj, &&l_prop, &&l_str, &&l_default };
			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);
			goto *dispatch[header & 3];

			l_obj: new_off = gc_reserve_object(ctx, old_off); goto l_done;
			l_prop: new_off = gc_reserve_prop(ctx, old_off); goto l_done;
			l_str: new_off = gc_copy_string(ctx, old_off); goto l_done;
			l_default: return old_off;

			l_done: return (new_off != (jsoff_t)~0) ? new_off : old_off;
			}

			static jsval_t gc_fwd_val_callback(void *ctx_ptr, jsval_t val) {
			gc_ctx_t ctx = (gc_ctx_t )ctx_ptr;
			return gc_update_val(ctx, val);
			}

			static jsoff_t gc_apply_off_callback(void *ctx_ptr, jsoff_t old_off) {
			gc_ctx_t ctx = (gc_ctx_t )ctx_ptr;
			if (old_off == 0) return 0;
			if (old_off >= ctx->js->brk) return old_off;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			return (new_off != (jsoff_t)~0) ? new_off : old_off;
			}

			static jsval_t gc_apply_val(gc_ctx_t *ctx, jsval_t val) {
			if (!gc_is_tagged(val)) return val;

			uint8_t type = gc_vtype(val);
			if (type == T_FUNC \|\| type == T_CLOSURE) return val;

			jsoff_t old_off = (jsoff_t)gc_vdata(val);
			if (old_off >= ctx->js->brk) return val;

			switch (type) {
			case T_OBJ:
			case T_ARR:
			case T_PROMISE:
			case T_GENERATOR:
			case T_STR:
			case T_PROP:
			case T_BIGINT:
			case T_SYMBOL: {
			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off != (jsoff_t)~0) return gc_mkval(type, new_off);
			break;
			}
			default: break;
			}

			return val;
			}

			static jsval_t gc_apply_val_callback(void *ctx_ptr, jsval_t val) {
			gc_ctx_t ctx = (gc_ctx_t )ctx_ptr;
			return gc_apply_val(ctx, val);
			}

			static jsoff_t gc_weak_off_callback(void *ctx_ptr, jsoff_t old_off) {
			gc_ctx_t ctx = (gc_ctx_t )ctx_ptr;
			if (old_off >= ctx->js->brk) return old_off;
			return fwd_lookup(&ctx->fwd, old_off);
			}

			static inline bool gc_get_stack_bounds(uintptr_t base, uintptr_t sp, uintptr_t lo, uintptr_t hi) {
			if (base == 0 \|\| sp == 0) return false;

			uintptr_t minp = (sp < base) ? sp : base;
			uintptr_t maxp = (sp < base) ? base : sp;

			uintptr_t aligned_lo = (minp + (uintptr_t)sizeof(uint64_t) - 1u) & ~((uintptr_t)sizeof(uint64_t) - 1u);
			uintptr_t aligned_hi = maxp & ~((uintptr_t)sizeof(uint64_t) - 1u);

			if (aligned_lo >= aligned_hi) return false;
			*lo = aligned_lo;
			*hi = aligned_hi;
			return true;
			}

			static inline bool gc_stack_word_readable(uintptr_t addr) {
			#if ANT_HAS_ASAN
			return __asan_region_is_poisoned((void *)addr, sizeof(uint64_t)) == NULL;
			#else
			return true;
			#endif
			}

			static inline bool gc_off_has_bytes(jsoff_t off, jsoff_t need, jsoff_t brk) {
			return off <= brk && need <= brk - off;
			}

			static inline bool gc_stack_word_valid(gc_ctx_t *ctx, uint8_t type, jsoff_t old_off, jsoff_t old_brk) {
			if (old_off == 0 \|\| old_off >= old_brk) return false;
			if (!gc_off_has_bytes(old_off, (jsoff_t)sizeof(jsoff_t), old_brk)) return false;

			jsoff_t header = gc_loadoff(ctx->js->mem, old_off);

			switch (type) {
			case T_OBJ:
			case T_ARR:
			case T_PROMISE:
			case T_GENERATOR: {
			if ((header & 3) != T_OBJ) return false;
			jsoff_t size = esize(header);
			return size != (jsoff_t)~0 && gc_off_has_bytes(old_off, size, old_brk);
			}
			case T_PROP: {
			if ((header & 3) != T_PROP) return false;
			jsoff_t size = esize(header);
			return size != (jsoff_t)~0 && gc_off_has_bytes(old_off, size, old_brk);
			}
			case T_STR: {
			if ((header & 3) != T_STR) return false;
			if ((header & ROPE_FLAG) != 0)
			return gc_off_has_bytes(old_off, (jsoff_t)sizeof(rope_node_t), old_brk);
			jsoff_t size = esize(header);
			return size != (jsoff_t)~0 && gc_off_has_bytes(old_off, size, old_brk);
			}
			case T_BIGINT: {
			if ((header & GC_BIGINT_HEADER_LOW_MASK) != 0) return false;
			jsoff_t payload = header >> GC_BIGINT_HEADER_SHIFT;
			if (payload < 2) return false;

			jsoff_t total = payload + (jsoff_t)sizeof(jsoff_t);
			total = (total + 7) & ~(jsoff_t)7;
			if (!gc_off_has_bytes(old_off, total, old_brk)) return false;

			jsoff_t sign_off = old_off + (jsoff_t)sizeof(jsoff_t);
			uint8_t sign = ctx->js->mem[sign_off];
			if (sign > 1) return false;

			jsoff_t nul_off = sign_off + payload - 1;
			return ctx->js->mem[nul_off] == 0;
			}
			case T_SYMBOL: {
			if ((header & GC_SYM_HEADER_LOW_MASK) != 0) return false;
			jsoff_t payload = header >> GC_SYM_HEADER_SHIFT;
			if (payload < GC_SYM_HEAP_FIXED) return false;

			jsoff_t total = payload + (jsoff_t)sizeof(jsoff_t);
			total = (total + 7) & ~(jsoff_t)7;
			return gc_off_has_bytes(old_off, total, old_brk);
			}
			default: return false;
			}
			}

			__attribute__((noinline))
			static void gc_scan_stack_reserve(gc_ctx_t *ctx) {
			jmp_buf jb;
			if (setjmp(jb) != 0) return;

			volatile uint8_t sp_marker = 0; uintptr_t lo, hi;
			if (!gc_get_stack_bounds((uintptr_t)ctx->js->cstk.base, (uintptr_t)&sp_marker, &lo, &hi)) return;

			jsoff_t old_brk = ctx->js->brk;

			for (uintptr_t addr = lo; addr < hi; addr += sizeof(uint64_t)) {
			if (!gc_stack_word_readable(addr)) continue;
			uint64_t w;
			memcpy(&w, (void *)addr, sizeof(w));

			if (w <= NANBOX_PREFIX) continue;

			uint8_t type = (w >> NANBOX_TYPE_SHIFT) & NANBOX_TYPE_MASK;
			if (type > T_FFI) continue;
			if (!((1u << type) & GC_HEAP_TYPE_MASK)) continue;

			jsoff_t old_off = (jsoff_t)(w & NANBOX_DATA_MASK);
			if (old_off == 0 \|\| old_off >= old_brk) continue;
			if (!gc_stack_word_valid(ctx, type, old_off, old_brk)) continue;

			if (fwd_lookup(&ctx->fwd, old_off) != (jsoff_t)~0) continue;
			gc_update_val(ctx, w);
			}
			}

			__attribute__((noinline))
			static void gc_scan_stack_update(gc_ctx_t *ctx) {
			jmp_buf jb;
			if (setjmp(jb) != 0) return;

			volatile uint8_t sp_marker = 0; uintptr_t lo, hi;
			if (!gc_get_stack_bounds((uintptr_t)ctx->js->cstk.base, (uintptr_t)&sp_marker, &lo, &hi)) return;

			jsoff_t old_brk = ctx->js->brk;

			for (uintptr_t addr = lo; addr < hi; addr += sizeof(uint64_t)) {
			if (!gc_stack_word_readable(addr)) continue;
			uint64_t w;
			memcpy(&w, (void *)addr, sizeof(w));

			if (w <= NANBOX_PREFIX) continue;

			uint8_t type = (w >> NANBOX_TYPE_SHIFT) & NANBOX_TYPE_MASK;
			if (type > T_FFI) continue;
			if (!((1u << type) & GC_HEAP_TYPE_MASK)) continue;

			jsoff_t old_off = (jsoff_t)(w & NANBOX_DATA_MASK);
			if (old_off == 0 \|\| old_off >= old_brk) continue;
			if (!gc_stack_word_valid(ctx, type, old_off, old_brk)) continue;

			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off == (jsoff_t)~0 \|\| new_off == old_off) continue;

			uint64_t updated = gc_mkval(type, new_off);
			memcpy((void *)addr, &updated, sizeof(updated));
			}
			}

			static void gc_scan_range_reserve(gc_ctx_t *ctx, uintptr_t lo, uintptr_t hi) {
			jsoff_t old_brk = ctx->js->brk;
			for (uintptr_t addr = lo; addr < hi; addr += sizeof(uint64_t)) {
			if (!gc_stack_word_readable(addr)) continue;
			uint64_t w;
			memcpy(&w, (void *)addr, sizeof(w));
			if (w <= NANBOX_PREFIX) continue;
			uint8_t type = (w >> NANBOX_TYPE_SHIFT) & NANBOX_TYPE_MASK;
			if (type > T_FFI) continue;
			if (!((1u << type) & GC_HEAP_TYPE_MASK)) continue;
			jsoff_t old_off = (jsoff_t)(w & NANBOX_DATA_MASK);
			if (old_off == 0 \|\| old_off >= old_brk) continue;
			if (!gc_stack_word_valid(ctx, type, old_off, old_brk)) continue;
			if (fwd_lookup(&ctx->fwd, old_off) != (jsoff_t)~0) continue;
			gc_update_val(ctx, w);
			}
			}

			static void gc_scan_range_update(gc_ctx_t *ctx, uintptr_t lo, uintptr_t hi) {
			jsoff_t old_brk = ctx->js->brk;
			for (uintptr_t addr = lo; addr < hi; addr += sizeof(uint64_t)) {
			if (!gc_stack_word_readable(addr)) continue;
			uint64_t w;
			memcpy(&w, (void *)addr, sizeof(w));
			if (w <= NANBOX_PREFIX) continue;
			uint8_t type = (w >> NANBOX_TYPE_SHIFT) & NANBOX_TYPE_MASK;
			if (type > T_FFI) continue;
			if (!((1u << type) & GC_HEAP_TYPE_MASK)) continue;
			jsoff_t old_off = (jsoff_t)(w & NANBOX_DATA_MASK);
			if (old_off == 0 \|\| old_off >= old_brk) continue;
			if (!gc_stack_word_valid(ctx, type, old_off, old_brk)) continue;
			jsoff_t new_off = fwd_lookup(&ctx->fwd, old_off);
			if (new_off == (jsoff_t)~0 \|\| new_off == old_off) continue;
			uint64_t updated = gc_mkval(type, new_off);
			memcpy((void *)addr, &updated, sizeof(updated));
			}
			}

			static inline void gc_scan_mco_stack(
			gc_ctx_t ctx, mco_coro mco, mco_coro *skip,
			void (scan)(gc_ctx_t , uintptr_t, uintptr_t)
			) {
			if (!mco \|\| mco == skip) return;
			if (!mco->stack_base \|\| mco->stack_size == 0) return;
			uintptr_t lo = (uintptr_t)mco->stack_base;
			uintptr_t hi = lo + mco->stack_size;
			scan(ctx, lo, hi);
			}

			static void gc_scan_other_stacks_reserve(gc_ctx_t *ctx) {
			mco_coro *running = mco_running();
			if (!running) return;

			for (mco_coro *a = running->prev_co; a; a = a->prev_co)
			gc_scan_mco_stack(ctx, a, running, gc_scan_range_reserve);

			for (coroutine_t *c = pending_coroutines.head; c; c = c->next)
			gc_scan_mco_stack(ctx, c->mco, running, gc_scan_range_reserve);

			if (ctx->js->cstk.main_base && ctx->js->cstk.main_lo) {
			uintptr_t lo, hi;
			if (gc_get_stack_bounds(
			(uintptr_t)ctx->js->cstk.main_base,
			(uintptr_t)ctx->js->cstk.main_lo, &lo, &hi)
			) gc_scan_range_reserve(ctx, lo, hi);
			}
			}

			static void gc_scan_other_stacks_update(gc_ctx_t *ctx) {
			mco_coro *running = mco_running();
			if (!running) return;

			for (mco_coro *a = running->prev_co; a; a = a->prev_co)
			gc_scan_mco_stack(ctx, a, running, gc_scan_range_update);

			for (coroutine_t *c = pending_coroutines.head; c; c = c->next)
			gc_scan_mco_stack(ctx, c->mco, running, gc_scan_range_update);

			if (ctx->js->cstk.main_base && ctx->js->cstk.main_lo) {
			uintptr_t lo, hi;
			if (gc_get_stack_bounds(
			(uintptr_t)ctx->js->cstk.main_base,
			(uintptr_t)ctx->js->cstk.main_lo, &lo, &hi)
			) gc_scan_range_update(ctx, lo, hi);
			}
			}

			static void gc_forward_func_cb(void ctx_ptr, sv_func_t func) {
			gc_ctx_t ctx = (gc_ctx_t )ctx_ptr;
			gc_update_func_constants(ctx, func, 0);
			}

			static void gc_compact(ant_t *js) {
			js->needs_gc = false;

			if (!js \|\| js->brk == 0) return;
			if (js->brk < 2 * 1024 * 1024) return;

			time_t now = time(NULL);
			if (now != (time_t)-1 && gc_last_run_time != 0) {
			double elapsed = difftime(now, gc_last_run_time);
			double cooldown;

			if (js->brk > 64 * 1024 * 1024) cooldown = 0.5;
			else if (js->brk > 16 * 1024 * 1024) cooldown = 1.0;
			else if (js->brk > 4 * 1024 * 1024) cooldown = 2.0;
			else cooldown = 4.0;

			if (elapsed >= 0.0
			&& elapsed < cooldown
			&& js->gc_alloc_since < js->brk / 4
			) return;
			}

			if (now != (time_t)-1) gc_last_run_time = now;
			size_t new_size = js->size;

			if (new_size > gc_scratch_size) {
			if (gc_scratch_buf) gc_munmap(gc_scratch_buf, gc_scratch_size);
			gc_scratch_buf = (uint8_t *)gc_mmap(new_size);
			gc_scratch_size = gc_scratch_buf ? new_size : 0;
			}

			if (!gc_scratch_buf) return;
			uint8_t *new_mem = gc_scratch_buf;

			size_t bitmap_size = (js->brk / 8 + 7) / 8 + 1;
			uint8_t mark_bits = (uint8_t )calloc(1, bitmap_size);
			if (!mark_bits) return;

			size_t estimated_objs = js->brk / 64;
			if (estimated_objs < 256) estimated_objs = 256;

			gc_ctx_t ctx;
			ctx.js = js;
			ctx.new_mem = new_mem;
			ctx.new_brk = NANBOX_HEAP_OFFSET;
			ctx.new_size = (jsoff_t)new_size;
			ctx.mark_bits = mark_bits;

			if (!fwd_init(&ctx.fwd, estimated_objs)) {
			free(mark_bits); return;
			}

			if (!work_init(&ctx.work, estimated_objs / 4 < 64 ? 64 : estimated_objs / 4)) {
			fwd_free(&ctx.fwd);
			free(mark_bits); return;
			}

			ctx.failed = false;
			gc_epoch_counter++;

			if (js->brk > 0) {
			jsoff_t header_at_0 = gc_loadoff(js->mem, 0);
			if ((header_at_0 & 3) == T_OBJ) gc_reserve_object(&ctx, 0);
			}

			js_gc_reserve_roots(js,
			gc_fwd_off_callback,
			gc_fwd_val_callback,
			&ctx
			); gc_drain_work_queue(&ctx);

			gc_scan_stack_reserve(&ctx);
			gc_scan_other_stacks_reserve(&ctx);
			gc_drain_work_queue(&ctx);

			if (ctx.failed) {
			free(mark_bits);
			work_free(&ctx.work);
			fwd_free(&ctx.fwd); return;
			}

			js_gc_visit_frame_funcs(js, gc_forward_func_cb, &ctx);
			gc_drain_work_queue(&ctx);

			js_gc_update_roots(js,
			gc_apply_off_callback,
			gc_weak_off_callback,
			gc_apply_val_callback,
			&ctx);

			gc_scan_stack_update(&ctx);
			gc_scan_other_stacks_update(&ctx);
			memcpy(js->mem, new_mem, ctx.new_brk);
			js->brk = ctx.new_brk;

			free(mark_bits);
			work_free(&ctx.work);
			fwd_free(&ctx.fwd);

			if (gc_scratch_buf && gc_scratch_size > 0) {
			RELEASE_PAGES(gc_scratch_buf, gc_scratch_size);
			}

			size_t new_brk = ctx.new_brk;
			size_t old_size = js->size;

			if (new_brk < old_size * 3 / 4 && old_size > ARENA_GROW_INCREMENT) {
			size_t target = ((new_brk * 3 / 2 + ARENA_GROW_INCREMENT - 1) / ARENA_GROW_INCREMENT) * ARENA_GROW_INCREMENT;
			if (target < ARENA_GROW_INCREMENT) target = ARENA_GROW_INCREMENT;
			if (target < old_size) { ant_arena_decommit(js->mem, old_size, target); js->size = (jsoff_t)target; }
			}
			}

			void js_gc_maybe(ant_t *js) {
			jsoff_t thresh = js->brk / 4;

			jsoff_t min_thresh = gc_throttled
			? 8 * 1024 * 1024
			: 2 * 1024 * 1024;

			jsoff_t max_thresh = gc_throttled
			? 64 * 1024 * 1024
			: 16 * 1024 * 1024;

			if (thresh < min_thresh) thresh = min_thresh;
			if (thresh > max_thresh) thresh = max_thresh;

			if (js->gc_alloc_since > thresh \|\| js->needs_gc) {
			gc_compact(js);
			js->gc_alloc_since = 0;
			}
			}

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ant/src/gc.c
8755416ca476master

gc.c
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ant/src/gc.c8755416ca476master

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ant/src/gc.c
8755416ca476master

gc.c
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