Function k2proto

third-party/lua-5.5.0/src/lcode.c:565–583

** Use scanner's table to cache position of constants in constant list ** and try to reuse constants. Because some values should not be used ** as keys (nil cannot be a key, integer keys can collapse with float ** keys), the caller must provide a useful 'key' for indexing the cache. */

** keys), the caller must provide a useful 'key' for indexing the cache.
*/
static int k2proto (FuncState *fs, TValue *key, TValue *v) {
  TValue val;
  Proto *f = fs->f;
  int tag = luaH_get(fs->kcache, key, &val);  /* query scanner table */
  if (!tagisempty(tag)) {  /* is there an index there? */
    int k = cast_int(ivalue(&val));
    /* collisions can happen only for float keys */
    lua_assert(ttisfloat(key) || luaV_rawequalobj(&f->k[k], v));
    return k;  /* reuse index */
  }
  else {  /* constant not found; create a new entry */
    int k = addk(fs, f, v);
    /* cache it for reuse; numerical value does not need GC barrier;
       table is not a metatable, so it does not need to invalidate cache */
    setivalue(&val, k);
    luaH_set(fs->ls->L, fs->kcache, key, &val);
    return k;
  }
}


/*