compiler-codegen/nova_rt/alloc.h - main - nv-lang/nova

compiler-codegen/nova_rt/alloc.h
88 строк4 KB
Evgeniy Golovin
fix(codegen): GC-root + cross-module merge for module-level lazy-static `ro` globals
14 июн 2026, 05:41
14 июн 2026, 05:41e22baf2
#ifndef NOVA_RT_ALLOC_H
#define NOVA_RT_ALLOC_H

#include <stddef.h>
#include <stdint.h>

/* GC interface — единственная точка контакта кодогенератора с памятью.
 * Реализация в alloc.c. Для смены GC — меняется только alloc.c.
 *
 * CONTRACT: nova_alloc MUST return zeroed memory. Codegen assumes zero-init
 * (record/closure/spawn-context fields are set by named assignment only;
 * unset fields must not contain garbage). All implementations must satisfy
 * this: alloc.c uses calloc, alloc_rc.c uses malloc+memset, alloc_boehm.c
 * relies on GC_malloc (Boehm API guarantee). */

void  nova_gc_init(void);
void  nova_gc_shutdown(void);
void* nova_alloc(size_t size);
void  nova_retain(void* ptr);
void  nova_release(void* ptr);

/* Plan 83.4.5.8 (2026-05-24): uncollectable allocation для cross-thread
 * объектов которые могут стать GC-unreachable между write и read despite
 * conceptual reachability (Boehm conservative scan miss). Manually freed
 * via nova_free_uncollectable.
 *
 * Use case: SpawnCtx под armed M:N — main thread alloc'ит + write'ит
 * fields, worker thread читает; promise GC-reachability через
 * `co->user_data` в arena-rooted memory empirically fails on Windows
 * (entire struct reads as zero). Uncollectable обходит race полностью.
 *
 * CONTRACT: nova_alloc_uncollectable MUST return zeroed memory (same
 * как nova_alloc). Caller MUST explicitly free через nova_free_uncollectable
 * чтобы избежать leak.
 *
 * Under Boehm: GC_malloc_uncollectable — внутренне tracked but не подверг
 * sweep. Memory persists until explicit GC_free.
 * Under malloc backend: identical to nova_alloc + free.
 * Under RC backend: identical to nova_alloc + nova_release. */
void* nova_alloc_uncollectable(size_t size);
void  nova_free_uncollectable(void* ptr);

/* Plan 152.4: register a static-storage pointer range [lo, hi) as a GC root.
 *
 * Module-level `ro NAME = EXPR` lazy-static globals store their value in a
 * file-scope `static T* _value;`. The Boehm backend runs with GC_set_no_dls(1)
 * (alloc_boehm.c) which, together with the Windows data-segment registration,
 * does NOT scan the program's static/BSS data — so such a static pointer is
 * NOT a GC root and its object is collected under memory pressure (latent until
 * a lazy-static held a large GC graph — the Unicode tables). The lazy-const
 * getter calls this once to register its storage cell as a root.
 *
 * Under malloc/RC backends: no-op (nothing is collected). */
void  nova_gc_add_root(void* lo, void* hi);

/* Instrumentation — available in all alloc implementations.
 * nova_gc_alloc_count : total allocations since nova_gc_init
 * nova_gc_free_count  : total frees/releases since nova_gc_init
 * nova_gc_live_count  : alloc_count - free_count (currently live objects)
 * nova_gc_reset_stats : zero all counters (for per-test isolation)
 */
size_t nova_gc_alloc_count(void);
size_t nova_gc_free_count(void);
size_t nova_gc_live_count(void);
void   nova_gc_reset_stats(void);

/* Plan 32: GC introspection API exposed to Nova via std.runtime.gc.
 * nova_gc_heap_size  : текущий размер heap в bytes (0 под malloc — honest sentinel)
 * nova_gc_collect    : принудительный сбор (no-op под malloc)
 * nova_gc_last_pause_ns : Plan 57.C.2 — длительность последнего collect-цикла
 *                          в наносекундах (0 под malloc; under Boehm — измеряется
 *                          через monotonic timer вокруг GC_gcollect). */
size_t   nova_gc_heap_size(void);
void     nova_gc_collect(void);
uint64_t nova_gc_last_pause_ns(void);

/* Plan 44.2 Этап 3: fiber arena introspection — std.runtime.fibers.
 *
 * На Windows (NOVA_FIBER_ARENA_ENABLED=0) все вернут 0 — honest sentinel
 * «arena не активна, fiber stacks идут через calloc-путь».
 * На Linux/macOS отражают per-thread arena stats. */
size_t nova_fibers_virtual_reserved(void);  /* bytes reserved via mmap */
size_t nova_fibers_slot_count(void);        /* total slots */
size_t nova_fibers_slots_active(void);      /* currently allocated */
size_t nova_fibers_high_water(void);        /* peak concurrent slots */
void   nova_fibers_compact(void);           /* P41-3: batch decay flush */

#endif /* NOVA_RT_ALLOC_H */