gc.h

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#ifndef POTION_GC_H
#define POTION_GC_H

#ifndef POTION_BIRTH_SIZE
#define POTION_BIRTH_SIZE  (PN_SIZE_T << 21)
#endif

#ifndef POTION_MIN_BIRTH_SIZE
#define POTION_MIN_BIRTH_SIZE  (PN_SIZE_T << 15)
#endif

#ifndef POTION_MAX_BIRTH_SIZE
#define POTION_MAX_BIRTH_SIZE (16 * POTION_BIRTH_SIZE)
#endif

#if POTION_MAX_BIRTH_SIZE < 4 * POTION_BIRTH_SIZE
#error invalid min and max birth sizes
#endif

#define POTION_GC_THRESHOLD (3 * POTION_BIRTH_SIZE)
#define POTION_GC_PERIOD    256
#define POTION_NB_ROOTS     64

#define SET_GEN(t, p, s) \
  M->t##_lo = p; \
  M->t##_cur = p + (sizeof(PN) * 2); \
  M->t##_hi = p + (s); \
  p = 0

#define SET_STOREPTR(n) \
  M->birth_storeptr = (void *)(((void **)M->birth_hi) - (n))

#define GC_KEEP(p) \
  *(M->birth_storeptr--) = (void *)p

#define DEL_BIRTH_REGION() \
  if (M->birth_lo == M && IN_BIRTH_REGION(M->protect)) { \
    void *protend = (void *)PN_ALIGN((_PN)M->protect, POTION_PAGESIZE); \
    pngc_page_delete(protend, (char *)M->birth_hi - (char *)protend); \
  } else { \
    void *protend = (void *)M->birth_lo; \
    pngc_page_delete(protend, (char *)M->birth_hi - (char *)protend); \
  }

#define IS_GC_PROTECTED(p) \
  ((_PN)(p) >= (_PN)M && (_PN)(p) < (_PN)M->protect)

#define IN_BIRTH_REGION(p) \
  ((_PN)(p) > (_PN)M->birth_lo && (_PN)(p) < (_PN)M->birth_hi)

#define IN_OLDER_REGION(p) \
  ((_PN)(p) > (_PN)M->old_lo && (_PN)(p) < (_PN)M->old_hi)

#define IS_NEW_PTR(p) \
  (PN_IS_PTR(p) && IN_BIRTH_REGION(p) && !IS_GC_PROTECTED(p))

#define GC_FORWARD(p, v) do { \
  struct PNFwd *_pnobj = (struct PNFwd *)v; \
  if (_pnobj->fwd == POTION_COPIED) \
    *(p) = _pnobj->ptr; \
  else \
    *(p) = (_PN)potion_gc_copy(P, (struct PNObject *)v); \
}  while(0)

#define GC_MINOR_UPDATE(p) do { \
  if (PN_IS_PTR(p)) { \
    PN _pnv = potion_fwd((_PN)p); \
    if (IN_BIRTH_REGION(_pnv) && !IS_GC_PROTECTED(_pnv)) \
      { GC_FORWARD((_PN *)&(p), _pnv); } \
  } \
} while(0)

#define GC_MAJOR_UPDATE(p) do { \
  if (PN_IS_PTR(p)) { \
    PN _pnv = potion_fwd((_PN)p); \
    if (!IS_GC_PROTECTED(_pnv) && \
        (IN_BIRTH_REGION(_pnv) || IN_OLDER_REGION(_pnv))) \
      {GC_FORWARD((_PN *)&(p), _pnv);} \
  } \
} while(0)

#define GC_MINOR_UPDATE_TABLE(name, kh, is_map) do { \
  unsigned k; \
  for (k = kh_begin(kh); k != kh_end(kh); ++k) \
    if (kh_exist(name, kh, k)) { \
      PN v1 = kh_key(name, kh, k); \
      GC_MINOR_UPDATE(v1); \
      kh_key(name, kh, k) = v1; \
      if (is_map) { \
        PN v2 = kh_val(name, kh, k); \
        GC_MINOR_UPDATE(v2); \
        kh_val(name, kh, k) = v2; \
      } \
    } \
} while (0)

#define GC_MAJOR_UPDATE_TABLE(name, kh, is_map) do { \
  unsigned k; \
  for (k = kh_begin(kh); k != kh_end(kh); ++k) \
    if (kh_exist(name, kh, k)) { \
      PN v1 = kh_key(name, kh, k); \
      GC_MAJOR_UPDATE(v1); \
      kh_key(name, kh, k) = v1; \
      if (is_map) { \
        PN v2 = kh_val(name, kh, k); \
        GC_MAJOR_UPDATE(v2); \
        kh_val(name, kh, k) = v2; \
      } \
    } \
} while (0)

#define GC_MINOR_STRINGS() do { \
  unsigned k; \
  GC_MINOR_UPDATE(P->strings); \
  for (k = kh_begin(P->strings); k != kh_end(P->strings); ++k) \
    if (kh_exist(str, P->strings, k)) { \
      PN v = kh_key(str, P->strings, k); \
      if (IN_BIRTH_REGION(v) && !IS_GC_PROTECTED(v)) { \
        if (((struct PNFwd *)v)->fwd == POTION_COPIED) \
          kh_key(str, P->strings, k) = ((struct PNFwd *)v)->ptr; \
        else \
          kh_del(str, P->strings, k); \
      } \
    } \
} while (0)

#define GC_MAJOR_STRINGS() do { \
  unsigned k; \
  GC_MAJOR_UPDATE(P->strings); \
  for (k = kh_begin(P->strings); k != kh_end(P->strings); ++k) \
    if (kh_exist(str, P->strings, k)) { \
      PN v = kh_key(str, P->strings, k); \
      if (!IS_GC_PROTECTED(v) && \
          (IN_BIRTH_REGION(v) || IN_OLDER_REGION(v))) { \
        if (((struct PNFwd *)v)->fwd == POTION_COPIED) \
          kh_key(str, P->strings, k) = ((struct PNFwd *)v)->ptr; \
        else \
          kh_del(str, P->strings, k); \
      } \
    } \
} while (0)

static inline int potion_birth_suggest(int need, volatile void *oldlo, volatile void *oldhi) {
  int suggest = ((char *)oldhi - (char *)oldlo) / 2;
  if (need * 2 > suggest) suggest = need * 2;
  if (POTION_MIN_BIRTH_SIZE > suggest)
    suggest = POTION_MIN_BIRTH_SIZE;
  else if (POTION_BIRTH_SIZE < suggest)
    suggest = POTION_BIRTH_SIZE;
  return PN_ALIGN(suggest, POTION_MIN_BIRTH_SIZE);
}

PN_SIZE potion_stack_len(Potion *, _PN **);
PN_SIZE potion_mark_stack(Potion *, int);
void *potion_gc_copy(Potion *, struct PNObject *);
void *pngc_page_new(int *, const char);
void *potion_mark_minor(Potion *, const struct PNObject *);
void *potion_mark_major(Potion *, const struct PNObject *);
void potion_gc_release(Potion *);

#endif