Function gxf

extlibs/lua/src/ldebug.c:520–528

** Check whether table being indexed by instruction 'i' is the ** environment '_ENV' */

** environment '_ENV'
*/
static const char *gxf (const Proto *p, int pc, Instruction i, int isup) {
  int t = GETARG_B(i);  /* table index */
  const char *name;  /* name of indexed variable */
  if (isup)  /* is an upvalue? */
    name = upvalname(p, t);
  else
    getobjname(p, pc, t, &name);
  return (name && strcmp(name, LUA_ENV) == 0) ? "global" : "field";
}


static const char *getobjname (const Proto *p, int lastpc, int reg,