text: /*
  ** vm.c - virtual machine for mruby
  **
  ** See Copyright Notice in mruby.h
  */
  
  #include <mruby.h>
  #include <mruby/array.h>
  #include <mruby/class.h>
  #include <mruby/hash.h>
  #include <mruby/irep.h>
  #include <mruby/numeric.h>
  #include <mruby/proc.h>
  #include <mruby/range.h>
  #include <mruby/string.h>
  #include <mruby/variable.h>
  #include <mruby/error.h>
  #include <mruby/opcode.h>
  #include "value_array.h"
  #include <mruby/throw.h>
  #include <mruby/dump.h>
  #include <mruby/presym.h>
  
  #ifdef MRB_NO_STDIO
  #if defined(__cplusplus)
  extern "C" {
  #endif
  void abort(void);
  #if defined(__cplusplus)
  }  /* extern "C" { */
  #endif
  #endif
  
  #define STACK_INIT_SIZE 128
  #define CALLINFO_INIT_SIZE 32
  
  /* Define amount of linear stack growth. */
  #ifndef MRB_STACK_GROWTH
  #define MRB_STACK_GROWTH 128
  #endif
  
  /* Maximum mrb_funcall() depth. Should be set lower on memory constrained systems. */
  #ifndef MRB_FUNCALL_DEPTH_MAX
  #define MRB_FUNCALL_DEPTH_MAX 512
  #endif
  
  /* Maximum stack depth. Should be set lower on memory constrained systems.
  The value below allows about 60000 recursive calls in the simplest case. */
  #ifndef MRB_STACK_MAX
  #define MRB_STACK_MAX (0x40000 - MRB_STACK_GROWTH)
  #endif
  
  #ifdef VM_DEBUG
  # define DEBUG(x) (x)
  #else
  # define DEBUG(x)
  #endif
  
  
  #ifndef MRB_GC_FIXED_ARENA
  static void
  mrb_gc_arena_shrink(mrb_state *mrb, int idx)
  {
    mrb_gc *gc = &mrb->gc;
    int capa = gc->arena_capa;
  
    if (idx < capa / 4) {
      capa >>= 2;
      if (capa < MRB_GC_ARENA_SIZE) {
        capa = MRB_GC_ARENA_SIZE;
      }
      if (capa != gc->arena_capa) {
        gc->arena = (struct RBasic**)mrb_realloc(mrb, gc->arena, sizeof(struct RBasic*)*capa);
        gc->arena_capa = capa;
      }
    }
  }
  #else
  #define mrb_gc_arena_shrink(mrb,idx)
  #endif
  
  #define CALL_MAXARGS 127
  
  void mrb_method_missing(mrb_state *mrb, mrb_sym name, mrb_value self, mrb_value args);
  
  static inline void
  stack_clear(mrb_value *from, size_t count)
  {
  #ifdef MRB_NAN_BOXING
    while (count-- > 0) {
      SET_NIL_VALUE(*from);
      from++;
    }
  #else
    memset(from, 0, sizeof(mrb_value)*count);
  #endif
  }
  
  static inline void
  stack_copy(mrb_value *dst, const mrb_value *src, size_t size)
  {
    memcpy(dst, src, sizeof(mrb_value)*size);
  }
  
  static void
  stack_init(mrb_state *mrb)
  {
    struct mrb_context *c = mrb->c;
  
    /* mrb_assert(mrb->stack == NULL); */
    c->stbase = (mrb_value *)mrb_calloc(mrb, STACK_INIT_SIZE, sizeof(mrb_value));
    c->stend = c->stbase + STACK_INIT_SIZE;
  
    /* mrb_assert(ci == NULL); */
    c->cibase = (mrb_callinfo *)mrb_calloc(mrb, CALLINFO_INIT_SIZE, sizeof(mrb_callinfo));
    c->ciend = c->cibase + CALLINFO_INIT_SIZE;
    c->ci = c->cibase;
    c->ci->u.target_class = mrb->object_class;
    c->ci->stack = c->stbase;
  }
  
  static inline void
  envadjust(mrb_state *mrb, mrb_value *oldbase, mrb_value *newbase, size_t oldsize)
  {
    mrb_callinfo *ci = mrb->c->cibase;
  
    if (newbase == oldbase) return;
    while (ci <= mrb->c->ci) {
      struct REnv *e = mrb_vm_ci_env(ci);
      mrb_value *st;
  
      if (e && MRB_ENV_ONSTACK_P(e) &&
          (st = e->stack) && oldbase <= st && st < oldbase+oldsize) {
        ptrdiff_t off = e->stack - oldbase;
  
        e->stack = newbase + off;
      }
  
      if (ci->proc && MRB_PROC_ENV_P(ci->proc) && e != MRB_PROC_ENV(ci->proc)) {
        e = MRB_PROC_ENV(ci->proc);
  
        if (e && MRB_ENV_ONSTACK_P(e) &&
            (st = e->stack) && oldbase <= st && st < oldbase+oldsize) {
          ptrdiff_t off = e->stack - oldbase;
  
          e->stack = newbase + off;
        }
      }
  
      ci->stack = newbase + (ci->stack - oldbase);
      ci++;
    }
  }
  
  /** def rec ; $deep =+ 1 ; if $deep > 1000 ; return 0 ; end ; rec ; end  */
  
  static void
  stack_extend_alloc(mrb_state *mrb, mrb_int room)
  {
    mrb_value *oldbase = mrb->c->stbase;
    mrb_value *newstack;
    size_t oldsize = mrb->c->stend - mrb->c->stbase;
    size_t size = oldsize;
    size_t off = mrb->c->ci->stack ? mrb->c->stend - mrb->c->ci->stack : 0;
  
    if (off > size) size = off;
  #ifdef MRB_STACK_EXTEND_DOUBLING
    if ((size_t)room <= size)
      size *= 2;
    else
      size += room;
  #else
    /* Use linear stack growth.
       It is slightly slower than doubling the stack space,
       but it saves memory on small devices. */
    if (room <= MRB_STACK_GROWTH)
      size += MRB_STACK_GROWTH;
    else
      size += room;
  #endif
  
    newstack = (mrb_value *)mrb_realloc_simple(mrb, mrb->c->stbase, sizeof(mrb_value) * size);
    if (newstack == NULL) {
      mrb_exc_raise(mrb, mrb_obj_value(mrb->stack_err));
    }
    stack_clear(&(newstack[oldsize]), size - oldsize);
    envadjust(mrb, oldbase, newstack, oldsize);
    mrb->c->stbase = newstack;
    mrb->c->stend = mrb->c->stbase + size;
  
    /* Raise an exception if the new stack size will be too large,
       to prevent infinite recursion. However, do this only after resizing the stack, so mrb_raise has stack space to work with. */
    if (size > MRB_STACK_MAX) {
      mrb_exc_raise(mrb, mrb_obj_value(mrb->stack_err));
    }
  }
  
  MRB_API void
  mrb_stack_extend(mrb_state *mrb, mrb_int room)
  {
    if (!mrb->c->ci->stack || mrb->c->ci->stack + room >= mrb->c->stend) {
      stack_extend_alloc(mrb, room);
    }
  }
  
  static inline struct REnv*
  uvenv(mrb_state *mrb, mrb_int up)
  {
    const struct RProc *proc = mrb->c->ci->proc;
    struct REnv *e;
  
    while (up--) {
      proc = proc->upper;
      if (!proc) return NULL;
    }
    e = MRB_PROC_ENV(proc);
    if (e) return e;              /* proc has enclosed env */
    else {
      mrb_callinfo *ci = mrb->c->ci;
      mrb_callinfo *cb = mrb->c->cibase;
  
      while (cb <= ci) {
        if (ci->proc == proc) {
          return mrb_vm_ci_env(ci);
        }
        ci--;
      }
    }
    return NULL;
  }
  
  static inline const struct RProc*
  top_proc(mrb_state *mrb, const struct RProc *proc)
  {
    while (proc->upper) {
      if (MRB_PROC_SCOPE_P(proc) || MRB_PROC_STRICT_P(proc))
        return proc;
      proc = proc->upper;
    }
    return proc;
  }
  
  #define CI_ACC_SKIP    -1
  #define CI_ACC_DIRECT  -2
  #define CI_ACC_RESUMED -3
  
  static inline mrb_callinfo*
  cipush(mrb_state *mrb, mrb_int push_stacks, mrb_int acc,
         struct RClass *target_class, const struct RProc *proc, mrb_sym mid, mrb_int argc)
  {
    struct mrb_context *c = mrb->c;
    mrb_callinfo *ci = c->ci;
  
    if (ci + 1 == c->ciend) {
      ptrdiff_t size = ci - c->cibase;
  
      c->cibase = (mrb_callinfo *)mrb_realloc(mrb, c->cibase, sizeof(mrb_callinfo)*size*2);
      c->ci = c->cibase + size;
      c->ciend = c->cibase + size * 2;
    }
    ci = ++c->ci;
    ci->mid = mid;
    mrb_vm_ci_proc_set(ci, proc);
    ci->stack = ci[-1].stack + push_stacks;
    ci->argc = (int16_t)argc;
    ci->acc = (int16_t)acc;
    ci->u.target_class = target_class;
  
    return ci;
  }
  
  void
  mrb_env_unshare(mrb_state *mrb, struct REnv *e)
  {
    if (e == NULL) return;
    else {
      size_t len = (size_t)MRB_ENV_LEN(e);
      mrb_value *p;
  
      if (!MRB_ENV_ONSTACK_P(e)) return;
      if (e->cxt != mrb->c) return;
      if (e == mrb_vm_ci_env(mrb->c->cibase)) return; /* for mirb */
      p = (mrb_value *)mrb_malloc(mrb, sizeof(mrb_value)*len);
      if (len > 0) {
        stack_copy(p, e->stack, len);
      }
      e->stack = p;
      MRB_ENV_CLOSE(e);
      mrb_write_barrier(mrb, (struct RBasic *)e);
    }
  }
  
  static inline mrb_callinfo*
  cipop(mrb_state *mrb)
  {
    struct mrb_context *c = mrb->c;
    struct REnv *env = mrb_vm_ci_env(c->ci);
  
    c->ci--;
    if (env) mrb_env_unshare(mrb, env);
    return c->ci;
  }
  
  MRB_API mrb_value
  mrb_protect_error(mrb_state *mrb, mrb_protect_error_func *body, void *userdata, mrb_bool *error)
  {
    struct mrb_jmpbuf *prev_jmp = mrb->jmp;
    struct mrb_jmpbuf c_jmp;
    mrb_value result = mrb_nil_value();
    int ai = mrb_gc_arena_save(mrb);
    const struct mrb_context *c = mrb->c;
    ptrdiff_t ci_index = c->ci - c->cibase;
  
    if (error) { *error = FALSE; }
  
    MRB_TRY(&c_jmp) {
      mrb->jmp = &c_jmp;
      result = body(mrb, userdata);
      mrb->jmp = prev_jmp;
    }
    MRB_CATCH(&c_jmp) {
      mrb->jmp = prev_jmp;
      result = mrb_obj_value(mrb->exc);
      mrb->exc = NULL;
      if (error) { *error = TRUE; }
      if (mrb->c == c) {
        while (c->ci - c->cibase > ci_index) {
          cipop(mrb);
        }
      }
      else {
        // It was probably switched by mrb_fiber_resume().
        // Simply destroy all successive CI_ACC_DIRECTs once the fiber has been switched.
        c = mrb->c;
        while (c->ci > c->cibase && c->ci->acc == CI_ACC_DIRECT) {
          cipop(mrb);
        }
      }
    }
    MRB_END_EXC(&c_jmp);
  
    mrb_gc_arena_restore(mrb, ai);
    mrb_gc_protect(mrb, result);
    return result;
  }
  
  void mrb_exc_set(mrb_state *mrb, mrb_value exc);
  static mrb_value mrb_run(mrb_state *mrb, const struct RProc* proc, mrb_value self);
  
  #ifndef MRB_FUNCALL_ARGC_MAX
  #define MRB_FUNCALL_ARGC_MAX 16
  #endif
  
  MRB_API mrb_value
  mrb_funcall(mrb_state *mrb, mrb_value self, const char *name, mrb_int argc, ...)
  {
    mrb_value argv[MRB_FUNCALL_ARGC_MAX];
    va_list ap;
    mrb_int i;
    mrb_sym mid = mrb_intern_cstr(mrb, name);
  
    if (argc > MRB_FUNCALL_ARGC_MAX) {
      mrb_raise(mrb, E_ARGUMENT_ERROR, "Too long arguments. (limit=" MRB_STRINGIZE(MRB_FUNCALL_ARGC_MAX) ")");
    }
  
    va_start(ap, argc);
    for (i = 0; i < argc; i++) {
      argv[i] = va_arg(ap, mrb_value);
    }
    va_end(ap);
    return mrb_funcall_argv(mrb, self, mid, argc, argv);
  }
  
  MRB_API mrb_value
  mrb_funcall_id(mrb_state *mrb, mrb_value self, mrb_sym mid, mrb_int argc, ...)
  {
    mrb_value argv[MRB_FUNCALL_ARGC_MAX];
    va_list ap;
    mrb_int i;
  
    if (argc > MRB_FUNCALL_ARGC_MAX) {
      mrb_raise(mrb, E_ARGUMENT_ERROR, "Too long arguments. (limit=" MRB_STRINGIZE(MRB_FUNCALL_ARGC_MAX) ")");
    }
  
    va_start(ap, argc);
    for (i = 0; i < argc; i++) {
      argv[i] = va_arg(ap, mrb_value);
    }
    va_end(ap);
    return mrb_funcall_argv(mrb, self, mid, argc, argv);
  }
  
  static mrb_int
  ci_nregs(mrb_callinfo *ci)
  {
    const struct RProc *p;
    mrb_int n = 0;
  
    if (!ci) return 3;
    p = ci->proc;
    if (!p) {
      if (ci->argc < 0) return 3;
      return ci->argc+2;
    }
    if (!MRB_PROC_CFUNC_P(p) && p->body.irep) {
      n = p->body.irep->nregs;
    }
    if (ci->argc < 0) {
      if (n < 3) n = 3; /* self + args + blk */
    }
    if (ci->argc > n) {
      n = ci->argc + 2; /* self + blk */
    }
    return n;
  }
  
  MRB_API mrb_value
  mrb_funcall_with_block(mrb_state *mrb, mrb_value self, mrb_sym mid, mrb_int argc, const mrb_value *argv, mrb_value blk)
  {
    mrb_value val;
    int ai = mrb_gc_arena_save(mrb);
  
    if (!mrb->jmp) {
      struct mrb_jmpbuf c_jmp;
      ptrdiff_t nth_ci = mrb->c->ci - mrb->c->cibase;
  
      MRB_TRY(&c_jmp) {
        mrb->jmp = &c_jmp;
        /* recursive call */
        val = mrb_funcall_with_block(mrb, self, mid, argc, argv, blk);
        mrb->jmp = 0;
      }
      MRB_CATCH(&c_jmp) { /* error */
        while (nth_ci < (mrb->c->ci - mrb->c->cibase)) {
          cipop(mrb);
        }
        mrb->jmp = 0;
        val = mrb_obj_value(mrb->exc);
      }
      MRB_END_EXC(&c_jmp);
      mrb->jmp = 0;
    }
    else {
      mrb_method_t m;
      struct RClass *c;
      mrb_callinfo *ci;
      mrb_int n = ci_nregs(mrb->c->ci);
      ptrdiff_t voff = -1;
  
      if (!mrb->c->stbase) {
        stack_init(mrb);
      }
      if (argc < 0) {
        mrb_raisef(mrb, E_ARGUMENT_ERROR, "negative argc for funcall (%i)", argc);
      }
      c = mrb_class(mrb, self);
      m = mrb_method_search_vm(mrb, &c, mid);
      if (MRB_METHOD_UNDEF_P(m)) {
        mrb_sym missing = MRB_SYM(method_missing);
        mrb_value args = mrb_ary_new_from_values(mrb, argc, argv);
        m = mrb_method_search_vm(mrb, &c, missing);
        if (MRB_METHOD_UNDEF_P(m)) {
          mrb_method_missing(mrb, mid, self, args);
        }
        mrb_ary_unshift(mrb, args, mrb_symbol_value(mid));
        mrb_stack_extend(mrb, n+2);
        mrb->c->ci->stack[n+1] = args;
        argc = -1;
      }
      if (mrb->c->ci - mrb->c->cibase > MRB_FUNCALL_DEPTH_MAX) {
        mrb_exc_raise(mrb, mrb_obj_value(mrb->stack_err));
      }
      ci = cipush(mrb, n, 0, c, NULL, mid, argc);
      if (argc < 0) argc = 1;
      if (mrb->c->stbase <= argv && argv < mrb->c->stend) {
        voff = argv - mrb->c->stbase;
      }
      if (argc >= CALL_MAXARGS) {
        mrb_value args = mrb_ary_new_from_values(mrb, argc, argv);
  
        mrb->c->ci->stack[1] = args;
        ci->argc = -1;
        argc = 1;
      }
      mrb_stack_extend(mrb, argc + 2);
      if (MRB_METHOD_PROC_P(m)) {
        struct RProc *p = MRB_METHOD_PROC(m);
  
        mrb_vm_ci_proc_set(ci, p);
        if (!MRB_PROC_CFUNC_P(p)) {
          mrb_stack_extend(mrb, p->body.irep->nregs + argc);
        }
      }
      if (voff >= 0) {
        argv = mrb->c->stbase + voff;
      }
      mrb->c->ci->stack[0] = self;
      if (ci->argc > 0) {
        stack_copy(mrb->c->ci->stack+1, argv, argc);
      }
      mrb->c->ci->stack[argc+1] = blk;
  
      if (MRB_METHOD_CFUNC_P(m)) {
        ci->acc = CI_ACC_DIRECT;
        val = MRB_METHOD_CFUNC(m)(mrb, self);
        cipop(mrb);
      }
      else {
        ci->acc = CI_ACC_SKIP;
        val = mrb_run(mrb, MRB_METHOD_PROC(m), self);
      }
    }
    mrb_gc_arena_restore(mrb, ai);
    mrb_gc_protect(mrb, val);
    return val;
  }
  
  MRB_API mrb_value
  mrb_funcall_argv(mrb_state *mrb, mrb_value self, mrb_sym mid, mrb_int argc, const mrb_value *argv)
  {
    return mrb_funcall_with_block(mrb, self, mid, argc, argv, mrb_nil_value());
  }
  
  static mrb_value
  exec_irep(mrb_state *mrb, mrb_value self, struct RProc *p)
  {
    mrb_callinfo *ci = mrb->c->ci;
    int keep, nregs;
  
    ci->stack[0] = self;
    mrb_vm_ci_proc_set(ci, p);
    if (MRB_PROC_CFUNC_P(p)) {
      return MRB_PROC_CFUNC(p)(mrb, self);
    }
    nregs = p->body.irep->nregs;
    if (ci->argc < 0) keep = 3;
    else keep = ci->argc + 2;
    if (nregs < keep) {
      mrb_stack_extend(mrb, keep);
    }
    else {
      mrb_stack_extend(mrb, nregs);
      stack_clear(ci->stack+keep, nregs-keep);
    }
  
    cipush(mrb, 0, 0, NULL, NULL, 0, 0);
  
    return self;
  }
  
  mrb_value
  mrb_exec_irep(mrb_state *mrb, mrb_value self, struct RProc *p)
  {
    mrb_callinfo *ci = mrb->c->ci;
    if (ci->acc >= 0) {
      return exec_irep(mrb, self, p);
    }
    else {
      mrb_value ret;
      if (MRB_PROC_CFUNC_P(p)) {
        cipush(mrb, 0, CI_ACC_DIRECT, mrb_vm_ci_target_class(ci), p, ci->mid, ci->argc);
        ret = MRB_PROC_CFUNC(p)(mrb, self);
        cipop(mrb);
      }
      else {
        int keep = (ci->argc < 0 ? 1 : ci->argc) + 2 /* receiver + block */;
        ret = mrb_top_run(mrb, p, self, keep);
      }
      if (mrb->exc && mrb->jmp) {
        mrb_exc_raise(mrb, mrb_obj_value(mrb->exc));
      }
      return ret;
    }
  }
  
  /* 15.3.1.3.4  */
  /* 15.3.1.3.44 */
  /*
   *  call-seq:
   *     obj.send(symbol [, args...])        -> obj
   *     obj.__send__(symbol [, args...])      -> obj
   *
   *  Invokes the method identified by _symbol_, passing it any
   *  arguments specified. You can use <code>__send__</code> if the name
   *  +send+ clashes with an existing method in _obj_.
   *
   *     class Klass
   *       def hello(*args)
   *         "Hello " + args.join(' ')
   *       end
   *     end
   *     k = Klass.new
   *     k.send :hello, "gentle", "readers"   #=> "Hello gentle readers"
   */
  mrb_value
  mrb_f_send(mrb_state *mrb, mrb_value self)
  {
    mrb_sym name;
    mrb_value block, *regs;
    const mrb_value *argv;
    mrb_int argc, i, len;
    mrb_method_t m;
    struct RClass *c;
    mrb_callinfo *ci;
  
    mrb_get_args(mrb, "n*&", &name, &argv, &argc, &block);
    ci = mrb->c->ci;
    if (ci->acc < 0) {
    funcall:
      return mrb_funcall_with_block(mrb, self, name, argc, argv, block);
    }
  
    c = mrb_class(mrb, self);
    m = mrb_method_search_vm(mrb, &c, name);
    if (MRB_METHOD_UNDEF_P(m)) {            /* call method_mising */
      goto funcall;
    }
  
    ci->mid = name;
    ci->u.target_class = c;
    regs = mrb->c->ci->stack+1;
    /* remove first symbol from arguments */
    if (ci->argc >= 0) {
      for (i=0,len=ci->argc; i<len; i++) {
        regs[i] = regs[i+1];
      }
      ci->argc--;
    }
    else {                     /* variable length arguments */
      regs[0] = mrb_ary_subseq(mrb, regs[0], 1, RARRAY_LEN(regs[0]) - 1);
    }
  
    if (MRB_METHOD_CFUNC_P(m)) {
      if (MRB_METHOD_PROC_P(m)) {
        mrb_vm_ci_proc_set(ci, MRB_METHOD_PROC(m));
      }
      return MRB_METHOD_CFUNC(m)(mrb, self);
    }
    return exec_irep(mrb, self, MRB_METHOD_PROC(m));
  }
  
  static mrb_value
  eval_under(mrb_state *mrb, mrb_value self, mrb_value blk, struct RClass *c)
  {
    struct RProc *p;
    mrb_callinfo *ci;
    int nregs;
  
    if (mrb_nil_p(blk)) {
      mrb_raise(mrb, E_ARGUMENT_ERROR, "no block given");
    }
    ci = mrb->c->ci;
    if (ci->acc == CI_ACC_DIRECT) {
      return mrb_yield_with_class(mrb, blk, 1, &self, self, c);
    }
    ci->u.target_class = c;
    p = mrb_proc_ptr(blk);
    mrb_vm_ci_proc_set(ci, p);
    ci->argc = 1;
    ci->mid = ci[-1].mid;
    if (MRB_PROC_CFUNC_P(p)) {
      mrb_stack_extend(mrb, 3);
      mrb->c->ci->stack[0] = self;
      mrb->c->ci->stack[1] = self;
      mrb->c->ci->stack[2] = mrb_nil_value();
      return MRB_PROC_CFUNC(p)(mrb, self);
    }
    nregs = p->body.irep->nregs;
    if (nregs < 3) nregs = 3;
    mrb_stack_extend(mrb, nregs);
    mrb->c->ci->stack[0] = self;
    mrb->c->ci->stack[1] = self;
    stack_clear(mrb->c->ci->stack+2, nregs-2);
    ci = cipush(mrb, 0, 0, NULL, NULL, 0, 0);
  
    return self;
  }
  
  /* 15.2.2.4.35 */
  /*
   *  call-seq:
   *     mod.class_eval {| | block }  -> obj
   *     mod.module_eval {| | block } -> obj
   *
   *  Evaluates block in the context of _mod_. This can
   *  be used to add methods to a class. <code>module_eval</code> returns
   *  the result of evaluating its argument.
   */
  mrb_value
  mrb_mod_module_eval(mrb_state *mrb, mrb_value mod)
  {
    mrb_value a, b;
  
    if (mrb_get_args(mrb, "|S&", &a, &b) == 1) {
      mrb_raise(mrb, E_NOTIMP_ERROR, "module_eval/class_eval with string not implemented");
    }
    return eval_under(mrb, mod, b, mrb_class_ptr(mod));
  }
  
  /* 15.3.1.3.18 */
  /*
   *  call-seq:
   *     obj.instance_eval {| | block }                       -> obj
   *
   *  Evaluates the given block,within  the context of the receiver (_obj_).
   *  In order to set the context, the variable +self+ is set to _obj_ while
   *  the code is executing, giving the code access to _obj_'s
   *  instance variables. In the version of <code>instance_eval</code>
   *  that takes a +String+, the optional second and third
   *  parameters supply a filename and starting line number that are used
   *  when reporting compilation errors.
   *
   *     class KlassWithSecret
   *       def initialize
   *         @secret = 99
   *       end
   *     end
   *     k = KlassWithSecret.new
   *     k.instance_eval { @secret }   #=> 99
   */
  mrb_value
  mrb_obj_instance_eval(mrb_state *mrb, mrb_value self)
  {
    mrb_value a, b;
  
    if (mrb_get_args(mrb, "|S&", &a, &b) == 1) {
      mrb_raise(mrb, E_NOTIMP_ERROR, "instance_eval with string not implemented");
    }
    return eval_under(mrb, self, b, mrb_singleton_class_ptr(mrb, self));
  }
  
  MRB_API mrb_value
  mrb_yield_with_class(mrb_state *mrb, mrb_value b, mrb_int argc, const mrb_value *argv, mrb_value self, struct RClass *c)
  {
    struct RProc *p;
    mrb_sym mid = mrb->c->ci->mid;
    mrb_callinfo *ci;
    mrb_value val;
    mrb_int n;
  
    if (mrb_nil_p(b)) {
      mrb_raise(mrb, E_ARGUMENT_ERROR, "no block given");
    }
    ci = mrb->c->ci;
    n = ci_nregs(ci);
    if (ci - mrb->c->cibase > MRB_FUNCALL_DEPTH_MAX) {
      mrb_exc_raise(mrb, mrb_obj_value(mrb->stack_err));
    }
    p = mrb_proc_ptr(b);
    ci = cipush(mrb, n, CI_ACC_SKIP, c, p, mid, 0 /* dummy */);
    if (argc >= CALL_MAXARGS) {
      ci->argc = -1;
      n = 3;
    }
    else {
      ci->argc = (int)argc;
      n = argc + 2;
    }
    mrb_stack_extend(mrb, n);
    mrb->c->ci->stack[0] = self;
    if (ci->argc < 0) {
      mrb->c->ci->stack[1] = mrb_ary_new_from_values(mrb, argc, argv);
      argc = 1;
    }
    else if (argc > 0) {
      stack_copy(mrb->c->ci->stack+1, argv, argc);
    }
    mrb->c->ci->stack[argc+1] = mrb_nil_value();
  
    if (MRB_PROC_CFUNC_P(p)) {
      ci->acc = CI_ACC_DIRECT;
      val = MRB_PROC_CFUNC(p)(mrb, self);
      cipop(mrb);
    }
    else {
      val = mrb_run(mrb, p, self);
    }
    return val;
  }
  
  MRB_API mrb_value
  mrb_yield_argv(mrb_state *mrb, mrb_value b, mrb_int argc, const mrb_value *argv)
  {
    struct RProc *p = mrb_proc_ptr(b);
  
    return mrb_yield_with_class(mrb, b, argc, argv, MRB_PROC_ENV(p)->stack[0], MRB_PROC_TARGET_CLASS(p));
  }
  
  MRB_API mrb_value
  mrb_yield(mrb_state *mrb, mrb_value b, mrb_value arg)
  {
    struct RProc *p = mrb_proc_ptr(b);
  
    return mrb_yield_with_class(mrb, b, 1, &arg, MRB_PROC_ENV(p)->stack[0], MRB_PROC_TARGET_CLASS(p));
  }
  
  mrb_value
  mrb_yield_cont(mrb_state *mrb, mrb_value b, mrb_value self, mrb_int argc, const mrb_value *argv)
  {
    struct RProc *p;
    mrb_callinfo *ci;
  
    if (mrb_nil_p(b)) {
      mrb_raise(mrb, E_ARGUMENT_ERROR, "no block given");
    }
    if (!mrb_proc_p(b)) {
      mrb_raise(mrb, E_TYPE_ERROR, "not a block");
    }
  
    p = mrb_proc_ptr(b);
    ci = mrb->c->ci;
  
    mrb_stack_extend(mrb, 3);
    mrb->c->ci->stack[1] = mrb_ary_new_from_values(mrb, argc, argv);
    mrb->c->ci->stack[2] = mrb_nil_value();
    ci->argc = -1;
    return exec_irep(mrb, self, p);
  }
  
  static struct RBreak*
  break_new(mrb_state *mrb, uint32_t tag, const struct RProc *p, mrb_value val)
  {
    struct RBreak *brk;
  
    brk = MRB_OBJ_ALLOC(mrb, MRB_TT_BREAK, NULL);
    mrb_break_proc_set(brk, p);
    mrb_break_value_set(brk, val);
    mrb_break_tag_set(brk, tag);
  
    return brk;
  }
  
  #define MRB_CATCH_FILTER_RESCUE (UINT32_C(1) << MRB_CATCH_RESCUE)
  #define MRB_CATCH_FILTER_ENSURE (UINT32_C(1) << MRB_CATCH_ENSURE)
  #define MRB_CATCH_FILTER_ALL    (MRB_CATCH_FILTER_RESCUE | MRB_CATCH_FILTER_ENSURE)
  
  static const struct mrb_irep_catch_handler *
  catch_handler_find(mrb_state *mrb, mrb_callinfo *ci, const mrb_code *pc, uint32_t filter)
  {
    const mrb_irep *irep;
    ptrdiff_t xpc;
    size_t cnt;
    const struct mrb_irep_catch_handler *e;
  
  /* The comparison operators use `>` and `<=` because pc already points to the next instruction */
  #define catch_cover_p(pc, beg, end) ((pc) > (ptrdiff_t)(beg) && (pc) <= (ptrdiff_t)(end))
  
    if (ci->proc == NULL || MRB_PROC_CFUNC_P(ci->proc)) return NULL;
    irep = ci->proc->body.irep;
    if (irep->clen < 1) return NULL;
    xpc = pc - irep->iseq;
    /* If it retry at the top level, pc will be 0, so check with -1 as the start position */
    mrb_assert(catch_cover_p(xpc, -1, irep->ilen));
    if (!catch_cover_p(xpc, -1, irep->ilen)) return NULL;
  
    /* Currently uses a simple linear search to avoid processing complexity. */
    cnt = irep->clen;
    e = mrb_irep_catch_handler_table(irep) + cnt - 1;
    for (; cnt > 0; cnt --, e --) {
      if (((UINT32_C(1) << e->type) & filter) &&
          catch_cover_p(xpc, mrb_irep_catch_handler_unpack(e->begin), mrb_irep_catch_handler_unpack(e->end))) {
        return e;
      }
    }
  
  #undef catch_cover_p
  
    return NULL;
  }
  
  typedef enum {
    LOCALJUMP_ERROR_RETURN = 0,
    LOCALJUMP_ERROR_BREAK = 1,
    LOCALJUMP_ERROR_YIELD = 2
  } localjump_error_kind;
  
  static void
  localjump_error(mrb_state *mrb, localjump_error_kind kind)
  {
    char kind_str[3][7] = { "return", "break", "yield" };
    char kind_str_len[] = { 6, 5, 5 };
    static const char lead[] = "unexpected ";
    mrb_value msg;
    mrb_value exc;
  
    msg = mrb_str_new_capa(mrb, sizeof(lead) + 7);
    mrb_str_cat(mrb, msg, lead, sizeof(lead) - 1);
    mrb_str_cat(mrb, msg, kind_str[kind], kind_str_len[kind]);
    exc = mrb_exc_new_str(mrb, E_LOCALJUMP_ERROR, msg);
    mrb_exc_set(mrb, exc);
  }
  
  static void
  argnum_error(mrb_state *mrb, mrb_int num)
  {
    mrb_value exc;
    mrb_value str;
    mrb_int argc = mrb->c->ci->argc;
  
    if (argc < 0) {
      mrb_value args = mrb->c->ci->stack[1];
      if (mrb_array_p(args)) {
        argc = RARRAY_LEN(args);
      }
    }
    if (mrb->c->ci->mid) {
      str = mrb_format(mrb, "'%n': wrong number of arguments (%i for %i)",
                       mrb->c->ci->mid, argc, num);
    }
    else {
      str = mrb_format(mrb, "wrong number of arguments (%i for %i)", argc, num);
    }
    exc = mrb_exc_new_str(mrb, E_ARGUMENT_ERROR, str);
    mrb_exc_set(mrb, exc);
  }
  
  static mrb_bool
  break_tag_p(struct RBreak *brk, uint32_t tag)
  {
    return (brk != NULL && brk->tt == MRB_TT_BREAK) ? TRUE : FALSE;
  }
  
  static void
  prepare_tagged_break(mrb_state *mrb, uint32_t tag, const struct RProc *proc, mrb_value val)
  {
    if (break_tag_p((struct RBreak*)mrb->exc, tag)) {
      mrb_break_tag_set((struct RBreak*)mrb->exc, tag);
    }
    else {
      mrb->exc = (struct RObject*)break_new(mrb, tag, proc, val);
    }
  }
  
  #define THROW_TAGGED_BREAK(mrb, tag, proc, val) \
    do { \
      prepare_tagged_break(mrb, tag, proc, val); \
      goto L_CATCH_TAGGED_BREAK; \
    } while (0)
  
  #define UNWIND_ENSURE(mrb, ci, pc, tag, proc, val) \
    do { \
      ch = catch_handler_find(mrb, ci, pc, MRB_CATCH_FILTER_ENSURE); \
      if (ch) { \
        THROW_TAGGED_BREAK(mrb, tag, proc, val); \
      } \
    } while (0)
  
  /*
   *  CHECKPOINT_RESTORE(tag) {
   *    This part is executed when jumping by the same "tag" of RBreak (it is not executed the first time).
   *    Write the code required (initialization of variables, etc.) for the subsequent processing.
   *  }
   *  CHECKPOINT_MAIN(tag) {
   *    This part is always executed.
   *  }
   *  CHECKPOINT_END(tag);
   *
   *  ...
   *
   *  // Jump to CHECKPOINT_RESTORE with the same "tag".
   *  goto CHECKPOINT_LABEL_MAKE(tag);
   */
  
  #define CHECKPOINT_LABEL_MAKE(tag) L_CHECKPOINT_ ## tag
  
  #define CHECKPOINT_RESTORE(tag) \
    do { \
      if (FALSE) { \
        CHECKPOINT_LABEL_MAKE(tag): \
        do {
  
  #define CHECKPOINT_MAIN(tag) \
        } while (0); \
      } \
      do {
  
  #define CHECKPOINT_END(tag) \
      } while (0); \
    } while (0)
  
  #ifdef MRB_USE_DEBUG_HOOK
  #define CODE_FETCH_HOOK(mrb, irep, pc, regs) if ((mrb)->code_fetch_hook) (mrb)->code_fetch_hook((mrb), (irep), (pc), (regs));
  #else
  #define CODE_FETCH_HOOK(mrb, irep, pc, regs)
  #endif
  
  #ifdef MRB_BYTECODE_DECODE_OPTION
  #define BYTECODE_DECODER(x) ((mrb)->bytecode_decoder)?(mrb)->bytecode_decoder((mrb), (x)):(x)
  #else
  #define BYTECODE_DECODER(x) (x)
  #endif
  
  #ifndef MRB_NO_DIRECT_THREADING
  #if defined __GNUC__ || defined __clang__ || defined __INTEL_COMPILER
  #define DIRECT_THREADED
  #endif
  #endif /* ifndef MRB_NO_DIRECT_THREADING */
  
  #ifndef DIRECT_THREADED
  
  #define INIT_DISPATCH for (;;) { insn = BYTECODE_DECODER(*pc); CODE_FETCH_HOOK(mrb, irep, pc, regs); switch (insn) {
  #define CASE(insn,ops) case insn: pc++; FETCH_ ## ops (); mrb->c->ci->pc = pc; L_ ## insn ## _BODY:
  #define NEXT goto L_END_DISPATCH
  #define JUMP NEXT
  #define END_DISPATCH L_END_DISPATCH:;}}
  
  #else
  
  #define INIT_DISPATCH JUMP; return mrb_nil_value();
  #define CASE(insn,ops) L_ ## insn: pc++; FETCH_ ## ops (); mrb->c->ci->pc = pc; L_ ## insn ## _BODY:
  #define NEXT insn=BYTECODE_DECODER(*pc); CODE_FETCH_HOOK(mrb, irep, pc, regs); goto *optable[insn]
  #define JUMP NEXT
  
  #define END_DISPATCH
  
  #endif
  
  MRB_API mrb_value
  mrb_vm_run(mrb_state *mrb, const struct RProc *proc, mrb_value self, mrb_int stack_keep)
  {
    const mrb_irep *irep = proc->body.irep;
    mrb_value result;
    struct mrb_context *c = mrb->c;
    ptrdiff_t cioff = c->ci - c->cibase;
    mrb_int nregs = irep->nregs;
  
    if (!c->stbase) {
      stack_init(mrb);
    }
    if (stack_keep > nregs)
      nregs = stack_keep;
    mrb_stack_extend(mrb, nregs);
    stack_clear(c->ci->stack + stack_keep, nregs - stack_keep);
    c->ci->stack[0] = self;
    result = mrb_vm_exec(mrb, proc, irep->iseq);
    if (mrb->c != c) {
      if (mrb->c->fib) {
        mrb_write_barrier(mrb, (struct RBasic*)mrb->c->fib);
      }
      mrb->c = c;
    }
    else if (c->ci - c->cibase > cioff) {
      c->ci = c->cibase + cioff;
    }
    return result;
  }
  
  static mrb_bool
  check_target_class(mrb_state *mrb)
  {
    if (!mrb_vm_ci_target_class(mrb->c->ci)) {
      mrb_value exc = mrb_exc_new_lit(mrb, E_TYPE_ERROR, "no target class or module");
      mrb_exc_set(mrb, exc);
      return FALSE;
    }
    return TRUE;
  }
  
  mrb_value
  get_send_args(mrb_state *mrb, mrb_int argc, mrb_value *regs)
  {
    if (argc < 0) return regs[0];
    return mrb_ary_new_from_values(mrb, argc, regs);
  }
  
  mrb_value mrb_obj_missing(mrb_state *mrb, mrb_value mod);
  void mrb_hash_check_kdict(mrb_state *mrb, mrb_value self);
  void mrb_method_added(mrb_state *mrb, struct RClass *c, mrb_sym mid);
  
  MRB_API mrb_value
  mrb_vm_exec(mrb_state *mrb, const struct RProc *proc, const mrb_code *pc)
  {
    /* mrb_assert(MRB_PROC_CFUNC_P(proc)) */
    const mrb_irep *irep = proc->body.irep;
    const mrb_pool_value *pool = irep->pool;
    const mrb_sym *syms = irep->syms;
    mrb_code insn;
    int ai = mrb_gc_arena_save(mrb);
    struct mrb_jmpbuf *prev_jmp = mrb->jmp;
    struct mrb_jmpbuf c_jmp;
    uint32_t a;
    uint16_t b;
    uint16_t c;
    mrb_sym mid;
    const struct mrb_irep_catch_handler *ch;
  
  #ifdef DIRECT_THREADED
    static const void * const optable[] = {
  #define OPCODE(x,_) &&L_OP_ ## x,
  #include "mruby/ops.h"
  #undef OPCODE
    };
  #endif
  
    mrb_bool exc_catched = FALSE;
  RETRY_TRY_BLOCK:
  
    MRB_TRY(&c_jmp) {
  
    if (exc_catched) {
      exc_catched = FALSE;
      mrb_gc_arena_restore(mrb, ai);
      if (mrb->exc && mrb->exc->tt == MRB_TT_BREAK)
        goto L_BREAK;
      goto L_RAISE;
    }
    mrb->jmp = &c_jmp;
    mrb_vm_ci_proc_set(mrb->c->ci, proc);
  
  #define regs (mrb->c->ci->stack)
    INIT_DISPATCH {
      CASE(OP_NOP, Z) {
        /* do nothing */
        NEXT;
      }
  
      CASE(OP_MOVE, BB) {
        regs[a] = regs[b];
        NEXT;
      }
  
      CASE(OP_LOADL, BB) {
        switch (pool[b].tt) {   /* number */
        case IREP_TT_INT32:
          regs[a] = mrb_int_value(mrb, (mrb_int)pool[b].u.i32);
          break;
        case IREP_TT_INT64:
  #if defined(MRB_INT64)
          regs[a] = mrb_int_value(mrb, (mrb_int)pool[b].u.i64);
          break;
  #else
  #if defined(MRB_64BIT)
          if (INT32_MIN <= pool[b].u.i64 && pool[b].u.i64 <= INT32_MAX) {
            regs[a] = mrb_int_value(mrb, (mrb_int)pool[b].u.i64);
            break;
          }
  #endif
          goto L_INT_OVERFLOW;
  #endif
        case IREP_TT_BIGINT:
          goto L_INT_OVERFLOW;
  #ifndef MRB_NO_FLOAT
        case IREP_TT_FLOAT:
          regs[a] = mrb_float_value(mrb, pool[b].u.f);
          break;
  #endif
        default:
          /* should not happen (tt:string) */
          regs[a] = mrb_nil_value();
          break;
        }
        NEXT;
      }
  
      CASE(OP_LOADI, BB) {
        SET_FIXNUM_VALUE(regs[a], b);
        NEXT;
      }
  
      CASE(OP_LOADINEG, BB) {
        SET_FIXNUM_VALUE(regs[a], -b);
        NEXT;
      }
  
      CASE(OP_LOADI__1,B) goto L_LOADI;
      CASE(OP_LOADI_0,B) goto L_LOADI;
      CASE(OP_LOADI_1,B) goto L_LOADI;
      CASE(OP_LOADI_2,B) goto L_LOADI;
      CASE(OP_LOADI_3,B) goto L_LOADI;
      CASE(OP_LOADI_4,B) goto L_LOADI;
      CASE(OP_LOADI_5,B) goto L_LOADI;
      CASE(OP_LOADI_6,B) goto L_LOADI;
      CASE(OP_LOADI_7, B) {
      L_LOADI:
        SET_FIXNUM_VALUE(regs[a], (mrb_int)insn - (mrb_int)OP_LOADI_0);
        NEXT;
      }
  
      CASE(OP_LOADI16, BS) {
        SET_FIXNUM_VALUE(regs[a], (mrb_int)(int16_t)b);
        NEXT;
      }
  
      CASE(OP_LOADI32, BSS) {
        SET_INT_VALUE(mrb, regs[a], (int32_t)(((uint32_t)b<<16)+c));
        NEXT;
      }
  
      CASE(OP_LOADSYM, BB) {
        SET_SYM_VALUE(regs[a], syms[b]);
        NEXT;
      }
  
      CASE(OP_LOADNIL, B) {
        SET_NIL_VALUE(regs[a]);
        NEXT;
      }
  
      CASE(OP_LOADSELF, B) {
        regs[a] = regs[0];
        NEXT;
      }
  
      CASE(OP_LOADT, B) {
        SET_TRUE_VALUE(regs[a]);
        NEXT;
      }
  
      CASE(OP_LOADF, B) {
        SET_FALSE_VALUE(regs[a]);
        NEXT;
      }
  
      CASE(OP_GETGV, BB) {
        mrb_value val = mrb_gv_get(mrb, syms[b]);
        regs[a] = val;
        NEXT;
      }
  
      CASE(OP_SETGV, BB) {
        mrb_gv_set(mrb, syms[b], regs[a]);
        NEXT;
      }
  
      CASE(OP_GETSV, BB) {
        mrb_value val = mrb_vm_special_get(mrb, syms[b]);
        regs[a] = val;
        NEXT;
      }
  
      CASE(OP_SETSV, BB) {
        mrb_vm_special_set(mrb, syms[b], regs[a]);
        NEXT;
      }
  
      CASE(OP_GETIV, BB) {
        regs[a] = mrb_iv_get(mrb, regs[0], syms[b]);
        NEXT;
      }
  
      CASE(OP_SETIV, BB) {
        mrb_iv_set(mrb, regs[0], syms[b], regs[a]);
        NEXT;
      }
  
      CASE(OP_GETCV, BB) {
        mrb_value val;
        val = mrb_vm_cv_get(mrb, syms[b]);
        regs[a] = val;
        NEXT;
      }
  
      CASE(OP_SETCV, BB) {
        mrb_vm_cv_set(mrb, syms[b], regs[a]);
        NEXT;
      }
  
      CASE(OP_GETCONST, BB) {
        mrb_value val;
        mrb_sym sym = syms[b];
  
        val = mrb_vm_const_get(mrb, sym);
        regs[a] = val;
        NEXT;
      }
  
      CASE(OP_SETCONST, BB) {
        mrb_vm_const_set(mrb, syms[b], regs[a]);
        NEXT;
      }
  
      CASE(OP_GETMCNST, BB) {
        mrb_value val;
  
        val = mrb_const_get(mrb, regs[a], syms[b]);
        regs[a] = val;
        NEXT;
      }
  
      CASE(OP_SETMCNST, BB) {
        mrb_const_set(mrb, regs[a+1], syms[b], regs[a]);
        NEXT;
      }
  
      CASE(OP_GETUPVAR, BBB) {
        mrb_value *regs_a = regs + a;
        struct REnv *e = uvenv(mrb, c);
  
        if (e && b < MRB_ENV_LEN(e)) {
          *regs_a = e->stack[b];
        }
        else {
          *regs_a = mrb_nil_value();
        }
        NEXT;
      }
  
      CASE(OP_SETUPVAR, BBB) {
        struct REnv *e = uvenv(mrb, c);
  
        if (e) {
          mrb_value *regs_a = regs + a;
  
          if (b < MRB_ENV_LEN(e)) {
            e->stack[b] = *regs_a;
            mrb_write_barrier(mrb, (struct RBasic*)e);
          }
        }
        NEXT;
      }
  
      CASE(OP_JMP, S) {
        pc += (int16_t)a;
        JUMP;
      }
      CASE(OP_JMPIF, BS) {
        if (mrb_test(regs[a])) {
          pc += (int16_t)b;
          JUMP;
        }
        NEXT;
      }
      CASE(OP_JMPNOT, BS) {
        if (!mrb_test(regs[a])) {
          pc += (int16_t)b;
          JUMP;
        }
        NEXT;
      }
      CASE(OP_JMPNIL, BS) {
        if (mrb_nil_p(regs[a])) {
          pc += (int16_t)b;
          JUMP;
        }
        NEXT;
      }
  
      CASE(OP_JMPUW, S) {
        a = (uint32_t)((pc - irep->iseq) + (int16_t)a);
        CHECKPOINT_RESTORE(RBREAK_TAG_JUMP) {
          struct RBreak *brk = (struct RBreak*)mrb->exc;
          mrb_value target = mrb_break_value_get(brk);
          mrb_assert(mrb_integer_p(target));
          a = (uint32_t)mrb_integer(target);
          mrb_assert(a >= 0 && a < irep->ilen);
        }
        CHECKPOINT_MAIN(RBREAK_TAG_JUMP) {
          ch = catch_handler_find(mrb, mrb->c->ci, pc, MRB_CATCH_FILTER_ENSURE);
          if (ch) {
            /* avoiding a jump from a catch handler into the same handler */
            if (a < mrb_irep_catch_handler_unpack(ch->begin) || a >= mrb_irep_catch_handler_unpack(ch->end)) {
              THROW_TAGGED_BREAK(mrb, RBREAK_TAG_JUMP, proc, mrb_fixnum_value(a));
            }
          }
        }
        CHECKPOINT_END(RBREAK_TAG_JUMP);
  
        mrb->exc = NULL; /* clear break object */
        pc = irep->iseq + a;
        JUMP;
      }
  
      CASE(OP_EXCEPT, B) {
        mrb_value exc;
  
        if (mrb->exc == NULL) {
          exc = mrb_nil_value();
        }
        else {
          switch (mrb->exc->tt) {
          case MRB_TT_BREAK:
          case MRB_TT_EXCEPTION:
            exc = mrb_obj_value(mrb->exc);
            break;
          default:
            mrb_assert(!"bad mrb_type");
            exc = mrb_nil_value();
            break;
          }
          mrb->exc = NULL;
        }
        regs[a] = exc;
        NEXT;
      }
      CASE(OP_RESCUE, BB) {
        mrb_value exc = regs[a];  /* exc on stack */
        mrb_value e = regs[b];
        struct RClass *ec;
  
        switch (mrb_type(e)) {
        case MRB_TT_CLASS:
        case MRB_TT_MODULE:
          break;
        default:
          {
            mrb_value exc;
  
            exc = mrb_exc_new_lit(mrb, E_TYPE_ERROR,
                                      "class or module required for rescue clause");
            mrb_exc_set(mrb, exc);
            goto L_RAISE;
          }
        }
        ec = mrb_class_ptr(e);
        regs[b] = mrb_bool_value(mrb_obj_is_kind_of(mrb, exc, ec));
        NEXT;
      }
  
      CASE(OP_RAISEIF, B) {
        mrb_value exc = regs[a];
        if (mrb_break_p(exc)) {
          mrb->exc = mrb_obj_ptr(exc);
          goto L_BREAK;
        }
        mrb_exc_set(mrb, exc);
        if (mrb->exc) {
          goto L_RAISE;
        }
        NEXT;
      }
  
      CASE(OP_SENDV, BB) {
        c = CALL_MAXARGS;
        goto L_SEND;
      };
  
      CASE(OP_SENDVB, BB) {
        c = CALL_MAXARGS;
        goto L_SENDB;
      };
  
      CASE(OP_SEND, BBB)
      L_SEND:
      {
        /* push nil after arguments */
        int bidx = (c == CALL_MAXARGS) ? a+2 : a+c+1;
        SET_NIL_VALUE(regs[bidx]);
        goto L_SENDB;
      };
      L_SEND_SYM:
      {
        /* push nil after arguments */
        int bidx = (c == CALL_MAXARGS) ? a+2 : a+c+1;
        SET_NIL_VALUE(regs[bidx]);
        goto L_SENDB_SYM;
      };
  
      CASE(OP_SENDB, BBB)
      L_SENDB:
      mid = syms[b];
      L_SENDB_SYM:
      {
        mrb_int argc = (c == CALL_MAXARGS) ? -1 : c;
        mrb_int bidx = (argc < 0) ? a+2 : a+c+1;
        mrb_method_t m;
        struct RClass *cls;
        mrb_callinfo *ci = mrb->c->ci;
        mrb_value recv, blk;
  
        mrb_assert(bidx < irep->nregs);
  
        recv = regs[a];
        blk = regs[bidx];
        if (!mrb_nil_p(blk) && !mrb_proc_p(blk)) {
          blk = mrb_type_convert(mrb, blk, MRB_TT_PROC, MRB_SYM(to_proc));
          /* The stack might have been reallocated during mrb_type_convert(),
             see #3622 */
          regs[bidx] = blk;
        }
        cls = mrb_class(mrb, recv);
        m = mrb_method_search_vm(mrb, &cls, mid);
        if (MRB_METHOD_UNDEF_P(m)) {
          mrb_sym missing = MRB_SYM(method_missing);
          mrb_value args;
  
          if (mrb_func_basic_p(mrb, recv, missing, mrb_obj_missing)) {
          method_missing:
            args = get_send_args(mrb, argc, regs+a+1);
            mrb_method_missing(mrb, mid, recv, args);
          }
          if (mid != missing) {
            cls = mrb_class(mrb, recv);
          }
          m = mrb_method_search_vm(mrb, &cls, missing);
          if (MRB_METHOD_UNDEF_P(m)) goto method_missing; /* just in case */
          if (argc >= 0) {
            if (a+2 >= irep->nregs) {
              mrb_stack_extend(mrb, a+3);
            }
            regs[a+1] = mrb_ary_new_from_values(mrb, c, regs+a+1);
            regs[a+2] = blk;
            argc = -1;
          }
          mrb_ary_unshift(mrb, regs[a+1], mrb_symbol_value(mid));
          mid = missing;
        }
  
        /* push callinfo */
        ci = cipush(mrb, a, a, cls, NULL, mid, argc);
  
        if (MRB_METHOD_CFUNC_P(m)) {
          if (MRB_METHOD_PROC_P(m)) {
            struct RProc *p = MRB_METHOD_PROC(m);
  
            mrb_vm_ci_proc_set(ci, p);
            recv = p->body.func(mrb, recv);
          }
          else if (MRB_METHOD_NOARG_P(m) &&
                   (argc > 0 || (argc == -1 && RARRAY_LEN(regs[1]) != 0))) {
            argnum_error(mrb, 0);
            goto L_RAISE;
          }
          else {
            recv = MRB_METHOD_FUNC(m)(mrb, recv);
          }
          mrb_gc_arena_restore(mrb, ai);
          mrb_gc_arena_shrink(mrb, ai);
          if (mrb->exc) goto L_RAISE;
          ci = mrb->c->ci;
          if (mrb_proc_p(blk)) {
            struct RProc *p = mrb_proc_ptr(blk);
            if (p && !MRB_PROC_STRICT_P(p) && MRB_PROC_ENV(p) == mrb_vm_ci_env(&ci[-1])) {
              p->flags |= MRB_PROC_ORPHAN;
            }
          }
          if (!ci->u.target_class) { /* return from context modifying method (resume/yield) */
            if (ci->acc == CI_ACC_RESUMED) {
              mrb->jmp = prev_jmp;
              return recv;
            }
            else {
              mrb_assert(!MRB_PROC_CFUNC_P(ci[-1].proc));
              proc = ci[-1].proc;
              irep = proc->body.irep;
              pool = irep->pool;
              syms = irep->syms;
            }
          }
          mrb->c->ci->stack[0] = recv;
          /* pop stackpos */
          ci = cipop(mrb);
          pc = ci->pc;
        }
        else {
          /* setup environment for calling method */
          mrb_vm_ci_proc_set(ci, (proc = MRB_METHOD_PROC(m)));
          irep = proc->body.irep;
          pool = irep->pool;
          syms = irep->syms;
          mrb_stack_extend(mrb, (argc < 0 && irep->nregs < 3) ? 3 : irep->nregs);
          pc = irep->iseq;
        }
      }
      JUMP;
  
      CASE(OP_CALL, Z) {
        mrb_callinfo *ci;
        mrb_value recv = mrb->c->ci->stack[0];
        struct RProc *m = mrb_proc_ptr(recv);
  
        /* replace callinfo */
        ci = mrb->c->ci;
        ci->u.target_class = MRB_PROC_TARGET_CLASS(m);
        mrb_vm_ci_proc_set(ci, m);
        if (MRB_PROC_ENV_P(m)) {
          ci->mid = MRB_PROC_ENV(m)->mid;
        }
  
        /* prepare stack */
        if (MRB_PROC_CFUNC_P(m)) {
          recv = MRB_PROC_CFUNC(m)(mrb, recv);
          mrb_gc_arena_restore(mrb, ai);
          mrb_gc_arena_shrink(mrb, ai);
          if (mrb->exc) goto L_RAISE;
          /* pop stackpos */
          ci = cipop(mrb);
          pc = ci->pc;
          regs[ci[1].acc] = recv;
          irep = mrb->c->ci->proc->body.irep;
          pool = irep->pool;
          syms = irep->syms;
          JUMP;
        }
        else {
          /* setup environment for calling method */
          proc = m;
          irep = m->body.irep;
          if (!irep) {
            mrb->c->ci->stack[0] = mrb_nil_value();
            a = 0;
            c = OP_R_NORMAL;
            goto L_OP_RETURN_BODY;
          }
          pool = irep->pool;
          syms = irep->syms;
          mrb_stack_extend(mrb, irep->nregs);
          if (ci->argc < 0) {
            if (irep->nregs > 3) {
              stack_clear(regs+3, irep->nregs-3);
            }
          }
          else if (ci->argc+2 < irep->nregs) {
            stack_clear(regs+ci->argc+2, irep->nregs-ci->argc-2);
          }
          if (MRB_PROC_ENV_P(m)) {
            regs[0] = MRB_PROC_ENV(m)->stack[0];
          }
          pc = irep->iseq;
          JUMP;
        }
      }
  
      CASE(OP_SUPER, BB) {
        mrb_int argc = (b == CALL_MAXARGS) ? -1 : b;
        int bidx = (argc < 0) ? a+2 : a+b+1;
        mrb_method_t m;
        struct RClass *cls;
        mrb_callinfo *ci = mrb->c->ci;
        mrb_value recv, blk;
        const struct RProc *p = ci->proc;
        mrb_sym mid = ci->mid;
        struct RClass* target_class = MRB_PROC_TARGET_CLASS(p);
  
        if (MRB_PROC_ENV_P(p) && p->e.env->mid && p->e.env->mid != mid) { /* alias support */
          mid = p->e.env->mid;    /* restore old mid */
        }
        mrb_assert(bidx < irep->nregs);
  
        if (mid == 0 || !target_class) {
          mrb_value exc = mrb_exc_new_lit(mrb, E_NOMETHOD_ERROR, "super called outside of method");
          mrb_exc_set(mrb, exc);
          goto L_RAISE;
        }
        if (target_class->flags & MRB_FL_CLASS_IS_PREPENDED) {
          target_class = mrb_vm_ci_target_class(ci);
        }
        else if (target_class->tt == MRB_TT_MODULE) {
          target_class = mrb_vm_ci_target_class(ci);
          if (target_class->tt != MRB_TT_ICLASS) {
            goto super_typeerror;
          }
        }
        recv = regs[0];
        if (!mrb_obj_is_kind_of(mrb, recv, target_class)) {
        super_typeerror: ;
          mrb_value exc = mrb_exc_new_lit(mrb, E_TYPE_ERROR,
                                              "self has wrong type to call super in this context");
          mrb_exc_set(mrb, exc);
          goto L_RAISE;
        }
        blk = regs[bidx];
        if (!mrb_nil_p(blk) && !mrb_proc_p(blk)) {
          blk = mrb_type_convert(mrb, blk, MRB_TT_PROC, MRB_SYM(to_proc));
          /* The stack or ci stack might have been reallocated during
             mrb_type_convert(), see #3622 and #3784 */
          regs[bidx] = blk;
          ci = mrb->c->ci;
        }
        cls = target_class->super;
        m = mrb_method_search_vm(mrb, &cls, mid);
        if (MRB_METHOD_UNDEF_P(m)) {
          mrb_sym missing = MRB_SYM(method_missing);
          mrb_value args;
  
          if (mrb_func_basic_p(mrb, recv, missing, mrb_obj_missing)) {
          super_missing:
            args = get_send_args(mrb, argc, regs+a+1);
            mrb_no_method_error(mrb, mid, args, "no superclass method '%n'", mid);
          }
          if (mid != missing) {
            cls = mrb_class(mrb, recv);
          }
          m = mrb_method_search_vm(mrb, &cls, missing);
          if (MRB_METHOD_UNDEF_P(m)) goto super_missing; /* just in case */
          if (argc >= 0) {
            if (a+2 >= irep->nregs) {
              mrb_stack_extend(mrb, a+3);
            }
            regs[a+1] = mrb_ary_new_from_values(mrb, b, regs+a+1);
            regs[a+2] = blk;
            argc = -1;
          }
          mrb_ary_unshift(mrb, regs[a+1], mrb_symbol_value(mid));
          mid = missing;
        }
  
        /* push callinfo */
        ci = cipush(mrb, a, 0, cls, NULL, mid, argc);
  
        /* prepare stack */
        mrb->c->ci->stack[0] = recv;
  
        if (MRB_METHOD_CFUNC_P(m)) {
          mrb_value v;
  
          if (MRB_METHOD_PROC_P(m)) {
            mrb_vm_ci_proc_set(ci, MRB_METHOD_PROC(m));
          }
          v = MRB_METHOD_CFUNC(m)(mrb, recv);
          mrb_gc_arena_restore(mrb, ai);
          if (mrb->exc) goto L_RAISE;
          ci = mrb->c->ci;
          mrb_assert(!mrb_break_p(v));
          if (!mrb_vm_ci_target_class(ci)) { /* return from context modifying method (resume/yield) */
            if (ci->acc == CI_ACC_RESUMED) {
              mrb->jmp = prev_jmp;
              return v;
            }
            else {
              mrb_assert(!MRB_PROC_CFUNC_P(ci[-1].proc));
              proc = ci[-1].proc;
              irep = proc->body.irep;
              pool = irep->pool;
              syms = irep->syms;
            }
          }
          mrb->c->ci->stack[0] = v;
          ci = cipop(mrb);
          pc = ci->pc;
          JUMP;
        }
        else {
          /* fill callinfo */
          ci->acc = a;
  
          /* setup environment for calling method */
          mrb_vm_ci_proc_set(ci, (proc = MRB_METHOD_PROC(m)));
          irep = proc->body.irep;
          pool = irep->pool;
          syms = irep->syms;
          mrb_stack_extend(mrb, (argc < 0 && irep->nregs < 3) ? 3 : irep->nregs);
          pc = irep->iseq;
          JUMP;
        }
      }
  
      CASE(OP_ARGARY, BS) {
        mrb_int m1 = (b>>11)&0x3f;
        mrb_int r  = (b>>10)&0x1;
        mrb_int m2 = (b>>5)&0x1f;
        mrb_int kd = (b>>4)&0x1;
        mrb_int lv = (b>>0)&0xf;
        mrb_value *stack;
  
        if (mrb->c->ci->mid == 0 || mrb_vm_ci_target_class(mrb->c->ci) == NULL) {
          mrb_value exc;
  
        L_NOSUPER:
          exc = mrb_exc_new_lit(mrb, E_NOMETHOD_ERROR, "super called outside of method");
          mrb_exc_set(mrb, exc);
          goto L_RAISE;
        }
        if (lv == 0) stack = regs + 1;
        else {
          struct REnv *e = uvenv(mrb, lv-1);
          if (!e) goto L_NOSUPER;
          if (MRB_ENV_LEN(e) <= m1+r+m2+kd+1)
            goto L_NOSUPER;
          stack = e->stack + 1;
        }
        if (r == 0) {
          regs[a] = mrb_ary_new_from_values(mrb, m1+m2+kd, stack);
        }
        else {
          mrb_value *pp = NULL;
          struct RArray *rest;
          mrb_int len = 0;
  
          if (mrb_array_p(stack[m1])) {
            struct RArray *ary = mrb_ary_ptr(stack[m1]);
  
            pp = ARY_PTR(ary);
            len = ARY_LEN(ary);
          }
          regs[a] = mrb_ary_new_capa(mrb, m1+len+m2+kd);
          rest = mrb_ary_ptr(regs[a]);
          if (m1 > 0) {
            stack_copy(ARY_PTR(rest), stack, m1);
          }
          if (len > 0) {
            stack_copy(ARY_PTR(rest)+m1, pp, len);
          }
          if (m2 > 0) {
            stack_copy(ARY_PTR(rest)+m1+len, stack+m1+1, m2);
          }
          if (kd) {
            stack_copy(ARY_PTR(rest)+m1+len+m2, stack+m1+m2+1, kd);
          }
          ARY_SET_LEN(rest, m1+len+m2+kd);
        }
        regs[a+1] = stack[m1+r+m2];
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_ENTER, W) {
        mrb_int m1 = MRB_ASPEC_REQ(a);
        mrb_int o  = MRB_ASPEC_OPT(a);
        mrb_int r  = MRB_ASPEC_REST(a);
        mrb_int m2 = MRB_ASPEC_POST(a);
        mrb_int kd = (MRB_ASPEC_KEY(a) > 0 || MRB_ASPEC_KDICT(a))? 1 : 0;
        /* unused
        int b  = MRB_ASPEC_BLOCK(a);
        */
        mrb_int argc = mrb->c->ci->argc;
        mrb_value *argv = regs+1;
        mrb_value * const argv0 = argv;
        mrb_int const len = m1 + o + r + m2;
        mrb_int const blk_pos = len + kd + 1;
        mrb_value *blk = &argv[argc < 0 ? 1 : argc];
        mrb_value kdict = mrb_nil_value();
        mrb_int kargs = kd;
  
        /* arguments is passed with Array */
        if (argc < 0) {
          struct RArray *ary = mrb_ary_ptr(regs[1]);
          argv = ARY_PTR(ary);
          argc = (int)ARY_LEN(ary);
          mrb_gc_protect(mrb, regs[1]);
        }
  
        /* strict argument check */
        if (mrb->c->ci->proc && MRB_PROC_STRICT_P(mrb->c->ci->proc)) {
          if (argc < m1 + m2 || (r == 0 && argc > len + kd)) {
            argnum_error(mrb, m1+m2);
            goto L_RAISE;
          }
        }
        /* extract first argument array to arguments */
        else if (len > 1 && argc == 1 && mrb_array_p(argv[0])) {
          mrb_gc_protect(mrb, argv[0]);
          argc = (int)RARRAY_LEN(argv[0]);
          argv = RARRAY_PTR(argv[0]);
        }
  
        if (kd) {
          /* check last arguments is hash if method takes keyword arguments */
          if (argc == m1+m2) {
            kdict = mrb_hash_new(mrb);
            kargs = 0;
          }
          else {
            if (argv && argc > 0 && mrb_hash_p(argv[argc-1])) {
              kdict = argv[argc-1];
              mrb_hash_check_kdict(mrb, kdict);
            }
            else if (r || argc <= m1+m2+o
                     || !(mrb->c->ci->proc && MRB_PROC_STRICT_P(mrb->c->ci->proc))) {
              kdict = mrb_hash_new(mrb);
              kargs = 0;
            }
            else {
              argnum_error(mrb, m1+m2);
              goto L_RAISE;
            }
            if (MRB_ASPEC_KEY(a) > 0) {
              kdict = mrb_hash_dup(mrb, kdict);
            }
          }
        }
  
        /* no rest arguments */
        if (argc-kargs < len) {
          mrb_int mlen = m2;
          if (argc < m1+m2) {
            mlen = m1 < argc ? argc - m1 : 0;
          }
          regs[blk_pos] = *blk; /* move block */
          if (kd) regs[len + 1] = kdict;
  
          /* copy mandatory and optional arguments */
          if (argv0 != argv && argv) {
            value_move(&regs[1], argv, argc-mlen); /* m1 + o */
          }
          if (argc < m1) {
            stack_clear(&regs[argc+1], m1-argc);
          }
          /* copy post mandatory arguments */
          if (mlen) {
            value_move(&regs[len-m2+1], &argv[argc-mlen], mlen);
          }
          if (mlen < m2) {
            stack_clear(&regs[len-m2+mlen+1], m2-mlen);
          }
          /* initialize rest arguments with empty Array */
          if (r) {
            regs[m1+o+1] = mrb_ary_new_capa(mrb, 0);
          }
          /* skip initializer of passed arguments */
          if (o > 0 && argc-kargs > m1+m2)
            pc += (argc - kargs - m1 - m2)*3;
        }
        else {
          mrb_int rnum = 0;
          if (argv0 != argv) {
            regs[blk_pos] = *blk; /* move block */
            if (kd) regs[len + 1] = kdict;
            value_move(&regs[1], argv, m1+o);
          }
          if (r) {
            mrb_value ary;
  
            rnum = argc-m1-o-m2-kargs;
            ary = mrb_ary_new_from_values(mrb, rnum, argv+m1+o);
            regs[m1+o+1] = ary;
          }
          if (m2) {
            if (argc-m2 > m1) {
              value_move(&regs[m1+o+r+1], &argv[m1+o+rnum], m2);
            }
          }
          if (argv0 == argv) {
            regs[blk_pos] = *blk; /* move block */
            if (kd) regs[len + 1] = kdict;
          }
          pc += o*3;
        }
  
        /* format arguments for generated code */
        mrb->c->ci->argc = (int16_t)(len + kd);
  
        /* clear local (but non-argument) variables */
        if (irep->nlocals-blk_pos-1 > 0) {
          stack_clear(&regs[blk_pos+1], irep->nlocals-blk_pos-1);
        }
        JUMP;
      }
  
      CASE(OP_KARG, BB) {
        mrb_value k = mrb_symbol_value(syms[b]);
        mrb_value kdict = regs[mrb->c->ci->argc];
  
        if (!mrb_hash_p(kdict) || !mrb_hash_key_p(mrb, kdict, k)) {
          mrb_value str = mrb_format(mrb, "missing keyword: %v", k);
          mrb_exc_set(mrb, mrb_exc_new_str(mrb, E_ARGUMENT_ERROR, str));
          goto L_RAISE;
        }
        regs[a] = mrb_hash_get(mrb, kdict, k);
        mrb_hash_delete_key(mrb, kdict, k);
        NEXT;
      }
  
      CASE(OP_KEY_P, BB) {
        mrb_value k = mrb_symbol_value(syms[b]);
        mrb_value kdict = regs[mrb->c->ci->argc];
        mrb_bool key_p = FALSE;
  
        if (mrb_hash_p(kdict)) {
          key_p = mrb_hash_key_p(mrb, kdict, k);
        }
        regs[a] = mrb_bool_value(key_p);
        NEXT;
      }
  
      CASE(OP_KEYEND, Z) {
        mrb_value kdict = regs[mrb->c->ci->argc];
  
        if (mrb_hash_p(kdict) && !mrb_hash_empty_p(mrb, kdict)) {
          mrb_value keys = mrb_hash_keys(mrb, kdict);
          mrb_value key1 = RARRAY_PTR(keys)[0];
          mrb_value str = mrb_format(mrb, "unknown keyword: %v", key1);
          mrb_exc_set(mrb, mrb_exc_new_str(mrb, E_ARGUMENT_ERROR, str));
          goto L_RAISE;
        }
        NEXT;
      }
  
      CASE(OP_BREAK, B) {
        c = OP_R_BREAK;
        goto L_RETURN;
      }
      CASE(OP_RETURN_BLK, B) {
        c = OP_R_RETURN;
        goto L_RETURN;
      }
      CASE(OP_RETURN, B)
      c = OP_R_NORMAL;
      L_RETURN:
      {
        mrb_callinfo *ci;
  
        ci = mrb->c->ci;
        if (ci->mid) {
          mrb_value blk;
  
          if (ci->argc < 0) {
            blk = regs[2];
          }
          else {
            blk = regs[ci->argc+1];
          }
          if (mrb_proc_p(blk)) {
            struct RProc *p = mrb_proc_ptr(blk);
  
            if (!MRB_PROC_STRICT_P(p) &&
                ci > mrb->c->cibase && MRB_PROC_ENV(p) == mrb_vm_ci_env(&ci[-1])) {
              p->flags |= MRB_PROC_ORPHAN;
            }
          }
        }
  
        if (mrb->exc) {
        L_RAISE:
          ci = mrb->c->ci;
          if (ci == mrb->c->cibase) {
            ch = catch_handler_find(mrb, ci, pc, MRB_CATCH_FILTER_ALL);
            if (ch == NULL) goto L_FTOP;
            goto L_CATCH;
          }
          while ((ch = catch_handler_find(mrb, ci, pc, MRB_CATCH_FILTER_ALL)) == NULL) {
            ci = cipop(mrb);
            if (ci[1].acc == CI_ACC_SKIP && prev_jmp) {
              mrb->jmp = prev_jmp;
              MRB_THROW(prev_jmp);
            }
            pc = ci[0].pc;
            if (ci == mrb->c->cibase) {
              ch = catch_handler_find(mrb, ci, pc, MRB_CATCH_FILTER_ALL);
              if (ch == NULL) {
              L_FTOP:             /* fiber top */
                if (mrb->c == mrb->root_c) {
                  mrb->c->ci->stack = mrb->c->stbase;
                  goto L_STOP;
                }
                else {
                  struct mrb_context *c = mrb->c;
  
                  c->status = MRB_FIBER_TERMINATED;
                  mrb->c = c->prev;
                  c->prev = NULL;
                  goto L_RAISE;
                }
              }
              break;
            }
          }
        L_CATCH:
          if (ch == NULL) goto L_STOP;
          if (FALSE) {
          L_CATCH_TAGGED_BREAK: /* from THROW_TAGGED_BREAK() or UNWIND_ENSURE() */
            ci = mrb->c->ci;
          }
          proc = ci->proc;
          irep = proc->body.irep;
          pool = irep->pool;
          syms = irep->syms;
          mrb_stack_extend(mrb, irep->nregs);
          pc = irep->iseq + mrb_irep_catch_handler_unpack(ch->target);
        }
        else {
          mrb_int acc;
          mrb_value v;
  
          ci = mrb->c->ci;
          v = regs[a];
          mrb_gc_protect(mrb, v);
          switch (c) {
          case OP_R_RETURN:
            /* Fall through to OP_R_NORMAL otherwise */
            if (ci->acc >=0 && MRB_PROC_ENV_P(proc) && !MRB_PROC_STRICT_P(proc)) {
              const struct RProc *dst;
              mrb_callinfo *cibase;
              cibase = mrb->c->cibase;
              dst = top_proc(mrb, proc);
  
              if (MRB_PROC_ENV_P(dst)) {
                struct REnv *e = MRB_PROC_ENV(dst);
  
                if (!MRB_ENV_ONSTACK_P(e) || (e->cxt && e->cxt != mrb->c)) {
                  localjump_error(mrb, LOCALJUMP_ERROR_RETURN);
                  goto L_RAISE;
                }
              }
              /* check jump destination */
              while (cibase <= ci && ci->proc != dst) {
                if (ci->acc < 0) { /* jump cross C boundary */
                  localjump_error(mrb, LOCALJUMP_ERROR_RETURN);
                  goto L_RAISE;
                }
                ci--;
              }
              if (ci <= cibase) { /* no jump destination */
                localjump_error(mrb, LOCALJUMP_ERROR_RETURN);
                goto L_RAISE;
              }
              ci = mrb->c->ci;
              while (cibase <= ci && ci->proc != dst) {
                CHECKPOINT_RESTORE(RBREAK_TAG_RETURN_BLOCK) {
                  cibase = mrb->c->cibase;
                  dst = top_proc(mrb, proc);
                }
                CHECKPOINT_MAIN(RBREAK_TAG_RETURN_BLOCK) {
                  UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_RETURN_BLOCK, proc, v);
                }
                CHECKPOINT_END(RBREAK_TAG_RETURN_BLOCK);
                ci = cipop(mrb);
                pc = ci->pc;
              }
              proc = ci->proc;
              mrb->exc = NULL; /* clear break object */
              break;
            }
            /* fallthrough */
          case OP_R_NORMAL:
          NORMAL_RETURN:
            if (ci == mrb->c->cibase) {
              struct mrb_context *c;
              c = mrb->c;
  
              if (!c->prev) { /* toplevel return */
                regs[irep->nlocals] = v;
                goto CHECKPOINT_LABEL_MAKE(RBREAK_TAG_STOP);
              }
              if (!c->vmexec && c->prev->ci == c->prev->cibase) {
                mrb_value exc = mrb_exc_new_lit(mrb, E_FIBER_ERROR, "double resume");
                mrb_exc_set(mrb, exc);
                goto L_RAISE;
              }
              CHECKPOINT_RESTORE(RBREAK_TAG_RETURN_TOPLEVEL) {
                c = mrb->c;
              }
              CHECKPOINT_MAIN(RBREAK_TAG_RETURN_TOPLEVEL) {
                UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_RETURN_TOPLEVEL, proc, v);
              }
              CHECKPOINT_END(RBREAK_TAG_RETURN_TOPLEVEL);
              /* automatic yield at the end */
              c->status = MRB_FIBER_TERMINATED;
              mrb->c = c->prev;
              mrb->c->status = MRB_FIBER_RUNNING;
              c->prev = NULL;
              if (c->vmexec) {
                mrb_gc_arena_restore(mrb, ai);
                c->vmexec = FALSE;
                mrb->jmp = prev_jmp;
                return v;
              }
              ci = mrb->c->ci;
            }
            CHECKPOINT_RESTORE(RBREAK_TAG_RETURN) {
              /* do nothing */
            }
            CHECKPOINT_MAIN(RBREAK_TAG_RETURN) {
              UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_RETURN, proc, v);
            }
            CHECKPOINT_END(RBREAK_TAG_RETURN);
            mrb->exc = NULL; /* clear break object */
            break;
          case OP_R_BREAK:
            if (MRB_PROC_STRICT_P(proc)) goto NORMAL_RETURN;
            if (MRB_PROC_ORPHAN_P(proc)) {
              mrb_value exc;
  
            L_BREAK_ERROR:
              exc = mrb_exc_new_lit(mrb, E_LOCALJUMP_ERROR,
                                        "break from proc-closure");
              mrb_exc_set(mrb, exc);
              goto L_RAISE;
            }
            if (!MRB_PROC_ENV_P(proc) || !MRB_ENV_ONSTACK_P(MRB_PROC_ENV(proc))) {
              goto L_BREAK_ERROR;
            }
            else {
              struct REnv *e = MRB_PROC_ENV(proc);
  
              if (e->cxt != mrb->c) {
                goto L_BREAK_ERROR;
              }
            }
            CHECKPOINT_RESTORE(RBREAK_TAG_BREAK) {
              /* do nothing */
            }
            CHECKPOINT_MAIN(RBREAK_TAG_BREAK) {
              UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_BREAK, proc, v);
            }
            CHECKPOINT_END(RBREAK_TAG_BREAK);
            /* break from fiber block */
            if (ci == mrb->c->cibase && ci->pc) {
              struct mrb_context *c = mrb->c;
  
              mrb->c = c->prev;
              c->prev = NULL;
              ci = mrb->c->ci;
            }
            if (ci->acc < 0) {
              ci = cipop(mrb);
              mrb_gc_arena_restore(mrb, ai);
              mrb->c->vmexec = FALSE;
              mrb->exc = (struct RObject*)break_new(mrb, RBREAK_TAG_BREAK, proc, v);
              mrb->jmp = prev_jmp;
              MRB_THROW(prev_jmp);
            }
            if (FALSE) {
              struct RBreak *brk;
  
            L_BREAK:
              brk = (struct RBreak*)mrb->exc;
              proc = mrb_break_proc_get(brk);
              v = mrb_break_value_get(brk);
              ci = mrb->c->ci;
  
              switch (mrb_break_tag_get(brk)) {
  #define DISPATCH_CHECKPOINTS(n, i) case n: goto CHECKPOINT_LABEL_MAKE(n);
                RBREAK_TAG_FOREACH(DISPATCH_CHECKPOINTS)
  #undef DISPATCH_CHECKPOINTS
                default:
                  mrb_assert(!"wrong break tag");
              }
            }
            while (mrb->c->cibase < ci && ci[-1].proc != proc->upper) {
              if (ci[-1].acc == CI_ACC_SKIP) {
                goto L_BREAK_ERROR;
              }
              CHECKPOINT_RESTORE(RBREAK_TAG_BREAK_UPPER) {
                /* do nothing */
              }
              CHECKPOINT_MAIN(RBREAK_TAG_BREAK_UPPER) {
                UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_BREAK_UPPER, proc, v);
              }
              CHECKPOINT_END(RBREAK_TAG_BREAK_UPPER);
              ci = cipop(mrb);
              pc = ci->pc;
            }
            CHECKPOINT_RESTORE(RBREAK_TAG_BREAK_INTARGET) {
              /* do nothing */
            }
            CHECKPOINT_MAIN(RBREAK_TAG_BREAK_INTARGET) {
              UNWIND_ENSURE(mrb, ci, pc, RBREAK_TAG_BREAK_INTARGET, proc, v);
            }
            CHECKPOINT_END(RBREAK_TAG_BREAK_INTARGET);
            if (ci == mrb->c->cibase) {
              goto L_BREAK_ERROR;
            }
            mrb->exc = NULL; /* clear break object */
            break;
          default:
            /* cannot happen */
            break;
          }
          mrb_assert(ci == mrb->c->ci);
          mrb_assert(mrb->exc == NULL);
  
          if (mrb->c->vmexec && !mrb_vm_ci_target_class(ci)) {
            mrb_gc_arena_restore(mrb, ai);
            mrb->c->vmexec = FALSE;
            mrb->jmp = prev_jmp;
            return v;
          }
          acc = ci->acc;
          ci = cipop(mrb);
          if (acc == CI_ACC_SKIP || acc == CI_ACC_DIRECT) {
            mrb_gc_arena_restore(mrb, ai);
            mrb->jmp = prev_jmp;
            return v;
          }
          pc = ci[0].pc;
          DEBUG(fprintf(stderr, "from :%s\n", mrb_sym_name(mrb, ci->mid)));
          proc = mrb->c->ci->proc;
          irep = proc->body.irep;
          pool = irep->pool;
          syms = irep->syms;
  
          regs[acc] = v;
          mrb_gc_arena_restore(mrb, ai);
        }
        JUMP;
      }
  
      CASE(OP_BLKPUSH, BS) {
        int m1 = (b>>11)&0x3f;
        int r  = (b>>10)&0x1;
        int m2 = (b>>5)&0x1f;
        int kd = (b>>4)&0x1;
        int lv = (b>>0)&0xf;
        mrb_value *stack;
  
        if (lv == 0) stack = regs + 1;
        else {
          struct REnv *e = uvenv(mrb, lv-1);
          if (!e || (!MRB_ENV_ONSTACK_P(e) && e->mid == 0) ||
              MRB_ENV_LEN(e) <= m1+r+m2+1) {
            localjump_error(mrb, LOCALJUMP_ERROR_YIELD);
            goto L_RAISE;
          }
          stack = e->stack + 1;
        }
        if (mrb_nil_p(stack[m1+r+m2])) {
          localjump_error(mrb, LOCALJUMP_ERROR_YIELD);
          goto L_RAISE;
        }
        regs[a] = stack[m1+r+m2+kd];
        NEXT;
      }
  
    L_INT_OVERFLOW:
      {
        mrb_value exc = mrb_exc_new_lit(mrb, E_RANGE_ERROR, "integer overflow");
        mrb_exc_set(mrb, exc);
      }
      goto L_RAISE;
  
  #define TYPES2(a,b) ((((uint16_t)(a))<<8)|(((uint16_t)(b))&0xff))
  #define OP_MATH(op_name)                                                    \
    /* need to check if op is overridden */                                   \
    switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {                  \
      OP_MATH_CASE_INTEGER(op_name);                                          \
      OP_MATH_CASE_FLOAT(op_name, integer, float);                            \
      OP_MATH_CASE_FLOAT(op_name, float,  integer);                           \
      OP_MATH_CASE_FLOAT(op_name, float,  float);                             \
      OP_MATH_CASE_STRING_##op_name();                                        \
      default:                                                                \
        c = 1;                                                                \
        mid = MRB_OPSYM(op_name);                                             \
        goto L_SEND_SYM;                                                      \
    }                                                                         \
    NEXT;
  #define OP_MATH_CASE_INTEGER(op_name)                                       \
    case TYPES2(MRB_TT_INTEGER, MRB_TT_INTEGER):                              \
      {                                                                       \
        mrb_int x = mrb_integer(regs[a]), y = mrb_integer(regs[a+1]), z;      \
        if (mrb_int_##op_name##_overflow(x, y, &z))                           \
          OP_MATH_OVERFLOW_INT();                                             \
        else                                                                  \
          SET_INT_VALUE(mrb,regs[a], z);                                      \
      }                                                                       \
      break
  #ifdef MRB_NO_FLOAT
  #define OP_MATH_CASE_FLOAT(op_name, t1, t2) (void)0
  #else
  #define OP_MATH_CASE_FLOAT(op_name, t1, t2)                                     \
    case TYPES2(OP_MATH_TT_##t1, OP_MATH_TT_##t2):                                \
      {                                                                           \
        mrb_float z = mrb_##t1(regs[a]) OP_MATH_OP_##op_name mrb_##t2(regs[a+1]); \
        SET_FLOAT_VALUE(mrb, regs[a], z);                                         \
      }                                                                           \
      break
  #endif
  #define OP_MATH_OVERFLOW_INT() goto L_INT_OVERFLOW
  #define OP_MATH_CASE_STRING_add()                                           \
    case TYPES2(MRB_TT_STRING, MRB_TT_STRING):                                \
      regs[a] = mrb_str_plus(mrb, regs[a], regs[a+1]);                        \
      mrb_gc_arena_restore(mrb, ai);                                          \
      break
  #define OP_MATH_CASE_STRING_sub() (void)0
  #define OP_MATH_CASE_STRING_mul() (void)0
  #define OP_MATH_OP_add +
  #define OP_MATH_OP_sub -
  #define OP_MATH_OP_mul *
  #define OP_MATH_TT_integer MRB_TT_INTEGER
  #define OP_MATH_TT_float   MRB_TT_FLOAT
  
      CASE(OP_ADD, B) {
        OP_MATH(add);
      }
  
      CASE(OP_SUB, B) {
        OP_MATH(sub);
      }
  
      CASE(OP_MUL, B) {
        OP_MATH(mul);
      }
  
      CASE(OP_DIV, B) {
  #ifndef MRB_NO_FLOAT
        mrb_float x, y, f;
  #endif
  
        /* need to check if op is overridden */
        switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {
        case TYPES2(MRB_TT_INTEGER,MRB_TT_INTEGER):
          {
            mrb_int x = mrb_integer(regs[a]);
            mrb_int y = mrb_integer(regs[a+1]);
            mrb_int div = mrb_div_int(mrb, x, y);
            SET_INT_VALUE(mrb, regs[a], div);
          }
          NEXT;
  #ifndef MRB_NO_FLOAT
        case TYPES2(MRB_TT_INTEGER,MRB_TT_FLOAT):
          x = (mrb_float)mrb_integer(regs[a]);
          y = mrb_float(regs[a+1]);
          break;
        case TYPES2(MRB_TT_FLOAT,MRB_TT_INTEGER):
          x = mrb_float(regs[a]);
          y = (mrb_float)mrb_integer(regs[a+1]);
          break;
        case TYPES2(MRB_TT_FLOAT,MRB_TT_FLOAT):
          x = mrb_float(regs[a]);
          y = mrb_float(regs[a+1]);
          break;
  #endif
        default:
          c = 1;
          mid = MRB_OPSYM(div);
          goto L_SEND_SYM;
        }
  
  #ifndef MRB_NO_FLOAT
        f = mrb_div_float(x, y);
        SET_FLOAT_VALUE(mrb, regs[a], f);
  #endif
        NEXT;
      }
  
  #define OP_MATHI(op_name)                                                   \
    /* need to check if op is overridden */                                   \
    switch (mrb_type(regs[a])) {                                              \
      OP_MATHI_CASE_INTEGER(op_name);                                         \
      OP_MATHI_CASE_FLOAT(op_name);                                           \
      default:                                                                \
        SET_INT_VALUE(mrb,regs[a+1], b);                                      \
        c = 1;                                                                \
        mid = MRB_OPSYM(op_name);                                             \
        goto L_SEND_SYM;                                                      \
    }                                                                         \
    NEXT;
  #define OP_MATHI_CASE_INTEGER(op_name)                                      \
    case MRB_TT_INTEGER:                                                      \
      {                                                                       \
        mrb_int x = mrb_integer(regs[a]), y = (mrb_int)b, z;                  \
        if (mrb_int_##op_name##_overflow(x, y, &z))                           \
          OP_MATH_OVERFLOW_INT();                                             \
        else                                                                  \
          SET_INT_VALUE(mrb,regs[a], z);                                      \
      }                                                                       \
      break
  #ifdef MRB_NO_FLOAT
  #define OP_MATHI_CASE_FLOAT(op_name) (void)0
  #else
  #define OP_MATHI_CASE_FLOAT(op_name)                                        \
    case MRB_TT_FLOAT:                                                        \
      {                                                                       \
        mrb_float z = mrb_float(regs[a]) OP_MATH_OP_##op_name b;              \
        SET_FLOAT_VALUE(mrb, regs[a], z);                                     \
      }                                                                       \
      break
  #endif
  
      CASE(OP_ADDI, BB) {
        OP_MATHI(add);
      }
  
      CASE(OP_SUBI, BB) {
        OP_MATHI(sub);
      }
  
  #define OP_CMP_BODY(op,v1,v2) (v1(regs[a]) op v2(regs[a+1]))
  
  #ifdef MRB_NO_FLOAT
  #define OP_CMP(op,sym) do {\
    int result;\
    /* need to check if - is overridden */\
    switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {\
    case TYPES2(MRB_TT_INTEGER,MRB_TT_INTEGER):\
      result = OP_CMP_BODY(op,mrb_fixnum,mrb_fixnum);\
      break;\
    default:\
      c = 1;\
      mid = MRB_OPSYM(sym);\
      goto L_SEND_SYM;\
    }\
    if (result) {\
      SET_TRUE_VALUE(regs[a]);\
    }\
    else {\
      SET_FALSE_VALUE(regs[a]);\
    }\
  } while(0)
  #else
  #define OP_CMP(op, sym) do {\
    int result;\
    /* need to check if - is overridden */\
    switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {\
    case TYPES2(MRB_TT_INTEGER,MRB_TT_INTEGER):\
      result = OP_CMP_BODY(op,mrb_fixnum,mrb_fixnum);\
      break;\
    case TYPES2(MRB_TT_INTEGER,MRB_TT_FLOAT):\
      result = OP_CMP_BODY(op,mrb_fixnum,mrb_float);\
      break;\
    case TYPES2(MRB_TT_FLOAT,MRB_TT_INTEGER):\
      result = OP_CMP_BODY(op,mrb_float,mrb_fixnum);\
      break;\
    case TYPES2(MRB_TT_FLOAT,MRB_TT_FLOAT):\
      result = OP_CMP_BODY(op,mrb_float,mrb_float);\
      break;\
    default:\
      c = 1;\
      mid = MRB_OPSYM(sym);\
      goto L_SEND_SYM;\
    }\
    if (result) {\
      SET_TRUE_VALUE(regs[a]);\
    }\
    else {\
      SET_FALSE_VALUE(regs[a]);\
    }\
  } while(0)
  #endif
  
      CASE(OP_EQ, B) {
        if (mrb_obj_eq(mrb, regs[a], regs[a+1])) {
          SET_TRUE_VALUE(regs[a]);
        }
        else {
          OP_CMP(==,eq);
        }
        NEXT;
      }
  
      CASE(OP_LT, B) {
        OP_CMP(<,lt);
        NEXT;
      }
  
      CASE(OP_LE, B) {
        OP_CMP(<=,le);
        NEXT;
      }
  
      CASE(OP_GT, B) {
        OP_CMP(>,gt);
        NEXT;
      }
  
      CASE(OP_GE, B) {
        OP_CMP(>=,ge);
        NEXT;
      }
  
      CASE(OP_ARRAY, BB) {
        mrb_value v = mrb_ary_new_from_values(mrb, b, &regs[a]);
        regs[a] = v;
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
      CASE(OP_ARRAY2, BBB) {
        mrb_value v = mrb_ary_new_from_values(mrb, c, &regs[b]);
        regs[a] = v;
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_ARYCAT, B) {
        mrb_value splat = mrb_ary_splat(mrb, regs[a+1]);
        if (mrb_nil_p(regs[a])) {
          regs[a] = splat;
        }
        else {
          mrb_ary_concat(mrb, regs[a], splat);
        }
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_ARYPUSH, B) {
        mrb_ary_push(mrb, regs[a], regs[a+1]);
        NEXT;
      }
  
      CASE(OP_ARYDUP, B) {
        mrb_value ary = regs[a];
        if (mrb_array_p(ary)) {
          ary = mrb_ary_new_from_values(mrb, RARRAY_LEN(ary), RARRAY_PTR(ary));
        }
        else {
          ary = mrb_ary_new_from_values(mrb, 1, &ary);
        }
        regs[a] = ary;
        NEXT;
      }
  
      CASE(OP_AREF, BBB) {
        mrb_value v = regs[b];
  
        if (!mrb_array_p(v)) {
          if (c == 0) {
            regs[a] = v;
          }
          else {
            SET_NIL_VALUE(regs[a]);
          }
        }
        else {
          v = mrb_ary_ref(mrb, v, c);
          regs[a] = v;
        }
        NEXT;
      }
  
      CASE(OP_ASET, BBB) {
        mrb_ary_set(mrb, regs[b], c, regs[a]);
        NEXT;
      }
  
      CASE(OP_APOST, BBB) {
        mrb_value v = regs[a];
        int pre  = b;
        int post = c;
        struct RArray *ary;
        int len, idx;
  
        if (!mrb_array_p(v)) {
          v = mrb_ary_new_from_values(mrb, 1, &regs[a]);
        }
        ary = mrb_ary_ptr(v);
        len = (int)ARY_LEN(ary);
        if (len > pre + post) {
          v = mrb_ary_new_from_values(mrb, len - pre - post, ARY_PTR(ary)+pre);
          regs[a++] = v;
          while (post--) {
            regs[a++] = ARY_PTR(ary)[len-post-1];
          }
        }
        else {
          v = mrb_ary_new_capa(mrb, 0);
          regs[a++] = v;
          for (idx=0; idx+pre<len; idx++) {
            regs[a+idx] = ARY_PTR(ary)[pre+idx];
          }
          while (idx < post) {
            SET_NIL_VALUE(regs[a+idx]);
            idx++;
          }
        }
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_INTERN, B) {
        mrb_sym sym = mrb_intern_str(mrb, regs[a]);
  
        regs[a] = mrb_symbol_value(sym);
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_STRING, BB) {
        size_t len;
  
        len = pool[b].tt >> 2;
        if (pool[b].tt & IREP_TT_SFLAG) {
          regs[a] = mrb_str_new_static(mrb, pool[b].u.str, len);
        }
        else {
          regs[a] = mrb_str_new(mrb, pool[b].u.str, len);
        }
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_STRCAT, B) {
        mrb_str_concat(mrb, regs[a], regs[a+1]);
        NEXT;
      }
  
      CASE(OP_HASH, BB) {
        mrb_value hash = mrb_hash_new_capa(mrb, b);
        int i;
        int lim = a+b*2;
  
        for (i=a; i<lim; i+=2) {
          mrb_hash_set(mrb, hash, regs[i], regs[i+1]);
        }
        regs[a] = hash;
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_HASHADD, BB) {
        mrb_value hash;
        int i;
        int lim = a+b*2+1;
  
        hash = regs[a];
        mrb_ensure_hash_type(mrb, hash);
        for (i=a+1; i<lim; i+=2) {
          mrb_hash_set(mrb, hash, regs[i], regs[i+1]);
        }
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
      CASE(OP_HASHCAT, B) {
        mrb_value hash = regs[a];
  
        mrb_ensure_hash_type(mrb, hash);
        mrb_hash_merge(mrb, hash, regs[a+1]);
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_LAMBDA, BB)
      c = OP_L_LAMBDA;
      L_MAKE_LAMBDA:
      {
        struct RProc *p;
        const mrb_irep *nirep = irep->reps[b];
  
        if (c & OP_L_CAPTURE) {
          p = mrb_closure_new(mrb, nirep);
        }
        else {
          p = mrb_proc_new(mrb, nirep);
          p->flags |= MRB_PROC_SCOPE;
        }
        if (c & OP_L_STRICT) p->flags |= MRB_PROC_STRICT;
        regs[a] = mrb_obj_value(p);
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
      CASE(OP_BLOCK, BB) {
        c = OP_L_BLOCK;
        goto L_MAKE_LAMBDA;
      }
      CASE(OP_METHOD, BB) {
        c = OP_L_METHOD;
        goto L_MAKE_LAMBDA;
      }
  
      CASE(OP_RANGE_INC, B) {
        mrb_value val = mrb_range_new(mrb, regs[a], regs[a+1], FALSE);
        regs[a] = val;
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_RANGE_EXC, B) {
        mrb_value val = mrb_range_new(mrb, regs[a], regs[a+1], TRUE);
        regs[a] = val;
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_OCLASS, B) {
        regs[a] = mrb_obj_value(mrb->object_class);
        NEXT;
      }
  
      CASE(OP_CLASS, BB) {
        struct RClass *c = 0, *baseclass;
        mrb_value base, super;
        mrb_sym id = syms[b];
  
        base = regs[a];
        super = regs[a+1];
        if (mrb_nil_p(base)) {
          baseclass = MRB_PROC_TARGET_CLASS(mrb->c->ci->proc);
          if (!baseclass) baseclass = mrb->object_class;
          base = mrb_obj_value(baseclass);
        }
        c = mrb_vm_define_class(mrb, base, super, id);
        regs[a] = mrb_obj_value(c);
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_MODULE, BB) {
        struct RClass *cls = 0, *baseclass;
        mrb_value base;
        mrb_sym id = syms[b];
  
        base = regs[a];
        if (mrb_nil_p(base)) {
          baseclass = MRB_PROC_TARGET_CLASS(mrb->c->ci->proc);
          if (!baseclass) baseclass = mrb->object_class;
          base = mrb_obj_value(baseclass);
        }
        cls = mrb_vm_define_module(mrb, base, id);
        regs[a] = mrb_obj_value(cls);
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_EXEC, BB)
      {
        mrb_value recv = regs[a];
        struct RProc *p;
        const mrb_irep *nirep = irep->reps[b];
  
        /* prepare closure */
        p = mrb_proc_new(mrb, nirep);
        p->c = NULL;
        mrb_field_write_barrier(mrb, (struct RBasic*)p, (struct RBasic*)proc);
        MRB_PROC_SET_TARGET_CLASS(p, mrb_class_ptr(recv));
        p->flags |= MRB_PROC_SCOPE;
  
        /* prepare call stack */
        cipush(mrb, a, a, mrb_class_ptr(recv), p, 0, 0);
  
        irep = p->body.irep;
        pool = irep->pool;
        syms = irep->syms;
        mrb_stack_extend(mrb, irep->nregs);
        stack_clear(regs+1, irep->nregs-1);
        pc = irep->iseq;
        JUMP;
      }
  
      CASE(OP_DEF, BB) {
        struct RClass *target = mrb_class_ptr(regs[a]);
        struct RProc *p = mrb_proc_ptr(regs[a+1]);
        mrb_method_t m;
        mrb_sym mid = syms[b];
  
        MRB_METHOD_FROM_PROC(m, p);
        mrb_define_method_raw(mrb, target, mid, m);
        mrb_method_added(mrb, target, mid);
        mrb_gc_arena_restore(mrb, ai);
        regs[a] = mrb_symbol_value(mid);
        NEXT;
      }
  
      CASE(OP_SCLASS, B) {
        regs[a] = mrb_singleton_class(mrb, regs[a]);
        mrb_gc_arena_restore(mrb, ai);
        NEXT;
      }
  
      CASE(OP_TCLASS, B) {
        if (!check_target_class(mrb)) goto L_RAISE;
        regs[a] = mrb_obj_value(mrb_vm_ci_target_class(mrb->c->ci));
        NEXT;
      }
  
      CASE(OP_ALIAS, BB) {
        struct RClass *target;
  
        if (!check_target_class(mrb)) goto L_RAISE;
        target = mrb_vm_ci_target_class(mrb->c->ci);
        mrb_alias_method(mrb, target, syms[a], syms[b]);
        mrb_method_added(mrb, target, syms[a]);
       NEXT;
      }
      CASE(OP_UNDEF, B) {
        struct RClass *target;
  
        if (!check_target_class(mrb)) goto L_RAISE;
        target = mrb_vm_ci_target_class(mrb->c->ci);
        mrb_undef_method_id(mrb, target, syms[a]);
        NEXT;
      }
  
      CASE(OP_DEBUG, Z) {
        FETCH_BBB();
  #ifdef MRB_USE_DEBUG_HOOK
        mrb->debug_op_hook(mrb, irep, pc, regs);
  #else
  #ifndef MRB_NO_STDIO
        printf("OP_DEBUG %d %d %d\n", a, b, c);
  #else
        abort();
  #endif
  #endif
        NEXT;
      }
  
      CASE(OP_ERR, B) {
        size_t len = pool[a].tt >> 2;
        mrb_value exc;
  
        mrb_assert((pool[a].tt&IREP_TT_NFLAG)==0);
        exc = mrb_exc_new(mrb, E_LOCALJUMP_ERROR, pool[a].u.str, len);
        mrb_exc_set(mrb, exc);
        goto L_RAISE;
      }
  
      CASE(OP_SENDVK, BB) {       /* not yet implemented */
        NEXT;
      }
  
      CASE(OP_EXT1, Z) {
        insn = READ_B();
        switch (insn) {
  #define OPCODE(insn,ops) case OP_ ## insn: FETCH_ ## ops ## _1(); mrb->c->ci->pc = pc; goto L_OP_ ## insn ## _BODY;
  #include "mruby/ops.h"
  #undef OPCODE
        }
        pc--;
        NEXT;
      }
      CASE(OP_EXT2, Z) {
        insn = READ_B();
        switch (insn) {
  #define OPCODE(insn,ops) case OP_ ## insn: FETCH_ ## ops ## _2(); mrb->c->ci->pc = pc; goto L_OP_ ## insn ## _BODY;
  #include "mruby/ops.h"
  #undef OPCODE
        }
        pc--;
        NEXT;
      }
      CASE(OP_EXT3, Z) {
        uint8_t insn = READ_B();
        switch (insn) {
  #define OPCODE(insn,ops) case OP_ ## insn: FETCH_ ## ops ## _3(); mrb->c->ci->pc = pc; goto L_OP_ ## insn ## _BODY;
  #include "mruby/ops.h"
  #undef OPCODE
        }
        pc--;
        NEXT;
      }
  
      CASE(OP_STOP, Z) {
        /*        stop VM */
        CHECKPOINT_RESTORE(RBREAK_TAG_STOP) {
          /* do nothing */
        }
        CHECKPOINT_MAIN(RBREAK_TAG_STOP) {
          UNWIND_ENSURE(mrb, mrb->c->ci, pc, RBREAK_TAG_STOP, proc, mrb_nil_value());
        }
        CHECKPOINT_END(RBREAK_TAG_STOP);
      L_STOP:
        mrb->jmp = prev_jmp;
        if (mrb->exc) {
          mrb_assert(mrb->exc->tt == MRB_TT_EXCEPTION);
          return mrb_obj_value(mrb->exc);
        }
        return regs[irep->nlocals];
      }
    }
    END_DISPATCH;
  #undef regs
    }
    MRB_CATCH(&c_jmp) {
      mrb_callinfo *ci = mrb->c->ci;
      while (ci > mrb->c->cibase && ci->acc == CI_ACC_DIRECT) {
        ci = cipop(mrb);
      }
      exc_catched = TRUE;
      pc = ci->pc;
      goto RETRY_TRY_BLOCK;
    }
    MRB_END_EXC(&c_jmp);
  }
  
  static mrb_value
  mrb_run(mrb_state *mrb, const struct RProc *proc, mrb_value self)
  {
    if (mrb->c->ci->argc < 0) {
      return mrb_vm_run(mrb, proc, self, 3); /* receiver, args and block) */
    }
    else {
      return mrb_vm_run(mrb, proc, self, mrb->c->ci->argc + 2); /* argc + 2 (receiver and block) */
    }
  }
  
  MRB_API mrb_value
  mrb_top_run(mrb_state *mrb, const struct RProc *proc, mrb_value self, mrb_int stack_keep)
  {
    mrb_value v;
  
    if (!mrb->c->cibase) {
      return mrb_vm_run(mrb, proc, self, stack_keep);
    }
    if (mrb->c->ci == mrb->c->cibase) {
      mrb_vm_ci_env_set(mrb->c->ci, NULL);
      return mrb_vm_run(mrb, proc, self, stack_keep);
    }
    cipush(mrb, 0, CI_ACC_SKIP, mrb->object_class, NULL, 0, 0);
    v = mrb_vm_run(mrb, proc, self, stack_keep);
  
    return v;
  }
  
  #if defined(MRB_USE_CXX_EXCEPTION) && defined(__cplusplus)
  # if !defined(MRB_USE_CXX_ABI)
  } /* end of extern "C" */
  # endif
  mrb_int mrb_jmpbuf::jmpbuf_id = 0;
  # if !defined(MRB_USE_CXX_ABI)
  extern "C" {
  # endif
  #endif
  