Merge branch 'master' into XCode

24 files changed, 814 insertions, 373 deletions

diff --git a/include/mrbconf.h b/include/mrbconf.h
index 20f49ec29..693e7da88 100644
--- a/include/mrbconf.h
+++ b/include/mrbconf.h
@@ -19,7 +19,10 @@
 /* number of object per heap page */
 //#define MRB_HEAP_PAGE_SIZE 1024
 
-/* initial size for IV khash */
+/* use segmented list for IV table */
+//#define MRB_USE_IV_SEGLIST
+
+/* initial size for IV khash; ignored when MRB_USE_IV_SEGLIST is set */
 //#define MRB_IV_INITIAL_SIZE 8
 
 /* default size of khash table bucket */
diff --git a/include/mruby.h b/include/mruby.h
index 451b4eb8b..380c5f24c 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -233,11 +233,12 @@ typedef struct mrb_state {
   int esize;
 
   struct RObject *exc;
-  struct kh_iv *globals;
+  struct iv_tbl *globals;
 
   struct mrb_irep **irep;
   size_t irep_len, irep_capa;
 
+  mrb_sym init_sym;
   struct RClass *object_class;
   struct RClass *class_class;
   struct RClass *module_class;
@@ -267,8 +268,9 @@ typedef struct mrb_state {
   struct RBasic *variable_gray_list; /* list of objects to be traversed atomically */
   size_t gc_live_after_mark;
   size_t gc_threshold;
-  mrb_int gc_interval_ratio;
-  mrb_int gc_step_ratio;
+  int gc_interval_ratio;
+  int gc_step_ratio;
+  int gc_disabled;
 
   mrb_sym symidx;
   struct kh_n2s *name2sym;      /* symbol table */
diff --git a/include/mruby/class.h b/include/mruby/class.h
index 2cc90310e..b4a2e9471 100644
--- a/include/mruby/class.h
+++ b/include/mruby/class.h
@@ -13,7 +13,7 @@ extern "C" {
 
 struct RClass {
   MRUBY_OBJECT_HEADER;
-  struct kh_iv *iv;
+  struct iv_tbl *iv;
   struct kh_mt *mt;
   struct RClass *super;
 };
diff --git a/include/mruby/data.h b/include/mruby/data.h
index 4c136555c..ca2a04b55 100644
--- a/include/mruby/data.h
+++ b/include/mruby/data.h
@@ -18,7 +18,7 @@ struct mrb_data_type {
 
 struct RData {
   MRUBY_OBJECT_HEADER;
-  struct kh_iv *iv;
+  struct iv_tbl *iv;
   struct mrb_data_type *type;
   void *data;
 };
diff --git a/include/mruby/hash.h b/include/mruby/hash.h
index f3755eb25..2b0aeeef2 100644
--- a/include/mruby/hash.h
+++ b/include/mruby/hash.h
@@ -13,7 +13,7 @@ extern "C" {
 
 struct RHash {
   MRUBY_OBJECT_HEADER;
-  struct kh_iv *iv;
+  struct iv_tbl *iv;
   struct kh_ht *ht;
 };
 
diff --git a/include/mruby/object.h b/include/mruby/object.h
index 4be060078..e42a5f428 100644
--- a/include/mruby/object.h
+++ b/include/mruby/object.h
@@ -44,7 +44,7 @@ struct RBasic {
 
 struct RObject {
   MRUBY_OBJECT_HEADER;
-  struct kh_iv *iv;
+  struct iv_tbl *iv;
 };
 
 #define mrb_obj_ptr(v)    ((struct RObject*)((v).value.p))
diff --git a/include/mruby/variable.h b/include/mruby/variable.h
index e93a77c55..0dac75c5b 100644
--- a/include/mruby/variable.h
+++ b/include/mruby/variable.h
@@ -38,17 +38,21 @@ mrb_value mrb_const_get(mrb_state*, mrb_value, mrb_sym);
 void mrb_const_set(mrb_state*, mrb_value, mrb_sym, mrb_value);
 int mrb_const_defined(mrb_state*, mrb_value, mrb_sym);
 
-mrb_value mrb_obj_iv_get(mrb_state*, struct RObject*, mrb_sym);
-void mrb_obj_iv_set(mrb_state*, struct RObject*, mrb_sym, mrb_value);
-const char * mrb_class2name(mrb_state *mrb, struct RClass* klass);
+mrb_value mrb_obj_iv_get(mrb_state *mrb, struct RObject *obj, mrb_sym sym);
+void mrb_obj_iv_set(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v);
+int mrb_obj_iv_defined(mrb_state *mrb, struct RObject *obj, mrb_sym sym);
 mrb_value mrb_iv_get(mrb_state *mrb, mrb_value obj, mrb_sym sym);
 void mrb_iv_set(mrb_state *mrb, mrb_value obj, mrb_sym sym, mrb_value v);
+int mrb_iv_defined(mrb_state*, mrb_value, mrb_sym);
 mrb_value mrb_iv_remove(mrb_state *mrb, mrb_value obj, mrb_sym sym);
+void mrb_iv_copy(mrb_state *mrb, mrb_value dst, mrb_value src);
 int mrb_const_defined_at(mrb_state *mrb, struct RClass *klass, mrb_sym id);
 mrb_value mrb_f_global_variables(mrb_state *mrb, mrb_value self);
 mrb_value mrb_gv_get(mrb_state *mrb, mrb_sym sym);
 void mrb_gv_set(mrb_state *mrb, mrb_sym sym, mrb_value val);
 mrb_value mrb_obj_instance_variables(mrb_state*, mrb_value);
+mrb_value mrb_obj_iv_inspect(mrb_state*, struct RObject*);
+mrb_sym mrb_class_sym(mrb_state *mrb, struct RClass *c, struct RClass *outer);
 
 /* GC functions */
 void mrb_gc_mark_gv(mrb_state*);
@@ -57,9 +61,6 @@ void mrb_gc_mark_iv(mrb_state*, struct RObject*);
 size_t mrb_gc_mark_iv_size(mrb_state*, struct RObject*);
 void mrb_gc_free_iv(mrb_state*, struct RObject*);
 
-#include "mruby/khash.h"
-KHASH_DECLARE(iv, mrb_sym, mrb_value, 1)
-
 #if defined(__cplusplus)
 }  /* extern "C" { */
 #endif
diff --git a/mrblib/print.rb b/mrblib/print.rb
index dea088e2b..9183f6bb2 100644
--- a/mrblib/print.rb
+++ b/mrblib/print.rb
@@ -48,8 +48,9 @@ module Kernel
       i = 0
       len = args.size
       while i < len
-        __printstr__ args[i].to_s
-        __printstr__ "\n"
+        s = args[i].to_s
+        __printstr__ s
+        __printstr__ "\n" if (s[-1] != "\n")
         i += 1
       end
       __printstr__ "\n" if len == 0
diff --git a/src/class.c b/src/class.c
index 7802c34bd..795527263 100644
--- a/src/class.c
+++ b/src/class.c
@@ -15,7 +15,6 @@
 #include "mruby/array.h"
 #include "error.h"
 
-KHASH_DEFINE(iv, mrb_sym, mrb_value,     1, kh_int_hash_func, kh_int_hash_equal);
 KHASH_DEFINE(mt, mrb_sym, struct RProc*, 1, kh_int_hash_func, kh_int_hash_equal);
 
 typedef struct fc_result {
@@ -65,30 +64,6 @@ mrb_name_class(mrb_state *mrb, struct RClass *c, mrb_sym name)
                  mrb_intern(mrb, "__classid__"), mrb_symbol_value(name));
 }
 
-static mrb_sym
-class_sym(mrb_state *mrb, struct RClass *c, struct RClass *outer)
-{
-  mrb_value name;
-
-  name = mrb_obj_iv_get(mrb, (struct RObject*)c, mrb_intern(mrb, "__classid__"));
-  if (mrb_nil_p(name)) {
-    khash_t(iv)* h;
-    khiter_t k;
-    mrb_value v;
-
-    if (!outer) outer = mrb->object_class;
-    h = outer->iv;
-    for (k = kh_begin(h); k != kh_end(h); k++) {
-      if (!kh_exist(h,k)) continue;
-      v = kh_value(h,k);
-      if (mrb_type(v) == c->tt && mrb_class_ptr(v) == c) {
-        return kh_key(h,k);
-      }
-    }
-  }
-  return SYM2ID(name);
-}
-
 static void
 make_metaclass(mrb_state *mrb, struct RClass *c)
 {
@@ -880,48 +855,10 @@ mrb_method_search(mrb_state *mrb, struct RClass* c, mrb_sym mid)
   return m;
 }
 
-#ifndef MRB_FUNCALL_ARGC_MAX
-#define MRB_FUNCALL_ARGC_MAX 16
-#endif
-
-mrb_value
-mrb_funcall(mrb_state *mrb, mrb_value self, const char *name, int argc, ...)
-{
-  mrb_sym mid = mrb_intern(mrb, name);
-  va_list ap;
-  int i;
-
-  if (argc == 0) {
-    return mrb_funcall_argv(mrb, self, mid, 0, 0);
-  }
-  else if (argc == 1) {
-    mrb_value v;
-
-    va_start(ap, argc);
-    v = va_arg(ap, mrb_value);
-    va_end(ap);
-    return mrb_funcall_argv(mrb, self, mid, 1, &v);
-  }
-  else {
-    mrb_value argv[MRB_FUNCALL_ARGC_MAX];
-
-    if (argc > MRB_FUNCALL_ARGC_MAX) {
-      mrb_raise(mrb, E_ARGUMENT_ERROR, "Too long arguments. (limit=%d)", 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);
-  }
-}
-
 void
 mrb_obj_call_init(mrb_state *mrb, mrb_value obj, int argc, mrb_value *argv)
 {
-  mrb_funcall_argv(mrb, obj, mrb_intern(mrb, "initialize"), argc, argv);
+  mrb_funcall_argv(mrb, obj, mrb->init_sym, argc, argv);
 }
 
 /*
@@ -960,7 +897,7 @@ mrb_class_new_instance_m(mrb_state *mrb, mrb_value klass)
   c = (struct RClass*)mrb_obj_alloc(mrb, k->tt, k);
   c->super = k;
   obj = mrb_obj_value(c);
-  mrb_funcall_with_block(mrb, obj, mrb_intern(mrb, "initialize"), argc, argv, blk);
+  mrb_funcall_with_block(mrb, obj, mrb->init_sym, argc, argv, blk);
 
   return obj;
 }
@@ -979,7 +916,7 @@ mrb_instance_new(mrb_state *mrb, mrb_value cv)
   o = (struct RObject*)mrb_obj_alloc(mrb, ttype, c);
   obj = mrb_obj_value(o);
   mrb_get_args(mrb, "*&", &argv, &argc, &blk);
-  mrb_funcall_with_block(mrb, obj, mrb_intern(mrb, "initialize"), argc, argv, blk);
+  mrb_funcall_with_block(mrb, obj, mrb->init_sym, argc, argv, blk);
 
   return obj;
 }
@@ -1086,16 +1023,16 @@ mrb_obj_respond_to(struct RClass* c, mrb_sym mid)
       k = kh_get(mt, h, mid);
       if (k != kh_end(h)) {
         if (kh_value(h, k)) {
-          return 1; /* exist method */
+          return TRUE;		/* method exists */
         }
         else {
-          return 0;
+          return FALSE;		/* undefined method */
         }
       }
     }
     c = c->super;
   }
-  return 0;  /* no method */
+  return FALSE;			/* no method */
 }
 
 int
@@ -1114,16 +1051,16 @@ mrb_class_path(mrb_state *mrb, struct RClass *c)
   path = mrb_obj_iv_get(mrb, (struct RObject*)c, mrb_intern(mrb, "__classpath__"));
   if (mrb_nil_p(path)) {
     struct RClass *outer = mrb_class_outer_module(mrb, c);
-    mrb_sym sym = class_sym(mrb, c, outer);
-    if (outer && outer != mrb->object_class) {
+    mrb_sym sym = mrb_class_sym(mrb, c, outer);
+    if (sym == 0) {
+      return mrb_nil_value();
+    }
+    else if (outer && outer != mrb->object_class) {
       mrb_value base = mrb_class_path(mrb, outer);
       path = mrb_str_plus(mrb, base, mrb_str_new(mrb, "::", 2));
       name = mrb_sym2name_len(mrb, sym, &len);
       mrb_str_concat(mrb, path, mrb_str_new(mrb, name, len));
     }
-    else if (sym == 0) {
-      return mrb_nil_value();
-    }
     else {
       name = mrb_sym2name_len(mrb, sym, &len);
       path = mrb_str_new(mrb, name, len);
diff --git a/src/codegen.c b/src/codegen.c
index bf6fd0b3e..38d57d581 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -142,6 +142,9 @@ genop(codegen_scope *s, mrb_code i)
   s->pc++;
 }
 
+#define NOVAL  0
+#define VAL    1
+
 static void
 genop_peep(codegen_scope *s, mrb_code i, int val)
 {
@@ -217,6 +220,7 @@ genop_peep(codegen_scope *s, mrb_code i, int val)
     case OP_SETCV:
     case OP_SETCONST:
     case OP_SETMCNST:
+    case OP_SETGLOBAL:
       if (c0 == OP_MOVE) {
         if (GETARG_A(i) == GETARG_A(i0)) {
           s->iseq[s->pc-1] = MKOP_ABx(c1, GETARG_B(i0), GETARG_Bx(i));
@@ -261,6 +265,17 @@ genop_peep(codegen_scope *s, mrb_code i, int val)
 	s->iseq[s->pc-1] = MKOP_ABC(c0, 0, GETARG_B(i0), GETARG_C(i0));
 	genop(s, MKOP_AB(OP_RETURN, 0, OP_R_NORMAL));
 	return;
+      case OP_SETIV:
+      case OP_SETCV:
+      case OP_SETCONST:
+      case OP_SETMCNST:
+      case OP_SETUPVAR:
+      case OP_SETGLOBAL:
+	s->pc--;
+	genop_peep(s, i0, NOVAL);
+	i0 = s->iseq[s->pc-1];
+	genop(s, MKOP_AB(OP_RETURN, GETARG_A(i0), OP_R_NORMAL));
+	return;
       case OP_LOADSYM:
       case OP_GETGLOBAL:
       case OP_GETIV:
@@ -436,9 +451,6 @@ lv_idx(codegen_scope *s, mrb_sym id)
   return 0;
 }
 
-#define NOVAL  0
-#define VAL    1
-
 static void
 for_body(codegen_scope *s, node *tree)
 {
@@ -598,10 +610,10 @@ static int
 nosplat(node *t)
 {
   while (t) {
-    if ((intptr_t)t->car->car == NODE_SPLAT) return 0;
+    if ((intptr_t)t->car->car == NODE_SPLAT) return FALSE;
     t = t->cdr;
   }
-  return 1;
+  return TRUE;
 }
 
 static mrb_sym
diff --git a/src/error.c b/src/error.c
index 6fe839cb2..150524f87 100644
--- a/src/error.c
+++ b/src/error.c
@@ -8,6 +8,7 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <setjmp.h>
+#include <string.h>
 #include "error.h"
 #include "mruby/variable.h"
 #include "mruby/string.h"
diff --git a/src/gc.c b/src/gc.c
index 9a630f626..0b01164d5 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -796,6 +796,7 @@ mrb_incremental_gc(mrb_state *mrb)
 {
   size_t limit = 0, result = 0;
 
+  if (mrb->gc_disabled) return;
   GC_INVOKE_TIME_REPORT;
   GC_TIME_START;
 
@@ -826,6 +827,7 @@ mrb_garbage_collect(mrb_state *mrb)
 {
   size_t max_limit = ~0;
 
+  if (mrb->gc_disabled) return;
   GC_INVOKE_TIME_REPORT;
   GC_TIME_START;
 
@@ -918,6 +920,51 @@ gc_start(mrb_state *mrb, mrb_value obj)
 
 /*
  *  call-seq:
+ *     GC.enable    -> true or false
+ *
+ *  Enables garbage collection, returning <code>true</code> if garbage
+ *  collection was previously disabled.
+ *
+ *     GC.disable   #=> false
+ *     GC.enable    #=> true
+ *     GC.enable    #=> false
+ *
+ */
+
+static mrb_value
+gc_enable(mrb_state *mrb, mrb_value obj)
+{
+  int old = mrb->gc_disabled;
+
+  mrb->gc_disabled = FALSE;
+  if (old) return mrb_true_value();
+  return mrb_false_value();
+}
+
+/*
+ *  call-seq:
+ *     GC.disable    -> true or false
+ *
+ *  Disables garbage collection, returning <code>true</code> if garbage
+ *  collection was already disabled.
+ *
+ *     GC.disable   #=> false
+ *     GC.disable   #=> true
+ *
+ */
+
+static mrb_value
+gc_disable(mrb_state *mrb, mrb_value obj)
+{
+  int old = mrb->gc_disabled;
+
+  mrb->gc_disabled = TRUE;
+  if (old) return mrb_true_value();
+  return mrb_false_value();
+}
+
+/*
+ *  call-seq:
  *     GC.interval_ratio      -> fixnum
  *
  *  Returns ratio of GC interval. Default value is 200(%).
@@ -989,6 +1036,8 @@ mrb_init_gc(mrb_state *mrb)
   gc = mrb_define_module(mrb, "GC");
 
   mrb_define_class_method(mrb, gc, "start", gc_start, ARGS_NONE());
+  mrb_define_class_method(mrb, gc, "enable", gc_enable, ARGS_NONE());
+  mrb_define_class_method(mrb, gc, "disable", gc_disable, ARGS_NONE());
   mrb_define_class_method(mrb, gc, "interval_ratio", gc_interval_ratio_get, ARGS_NONE());
   mrb_define_class_method(mrb, gc, "interval_ratio=", gc_interval_ratio_set, ARGS_REQ(1));
   mrb_define_class_method(mrb, gc, "step_ratio", gc_step_ratio_get, ARGS_NONE());
diff --git a/src/kernel.c b/src/kernel.c
index 6327f967d..1334d8f9f 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -32,50 +32,13 @@ struct obj_ivar_tag {
   void * arg;
 };
 
-static mrb_value
-inspect_obj(mrb_state *mrb, mrb_value obj, mrb_value str, int recur)
-{
-  if (recur) {
-    mrb_str_cat2(mrb, str, " ...");
-  }
-  else {
-    khiter_t k;
-    kh_iv_t *h = RCLASS_IV_TBL(obj);
-
-    if (h) {
-      for (k = kh_begin(h); k != kh_end(h); k++) {
-        if (kh_exist(h, k)){
-          mrb_sym id = kh_key(h, k);
-          mrb_value value = kh_value(h, k);
-
-          /* need not to show internal data */
-          if (RSTRING_PTR(str)[0] == '-') { /* first element */
-            RSTRING_PTR(str)[0] = '#';
-            mrb_str_cat2(mrb, str, " ");
-          }
-          else {
-            mrb_str_cat2(mrb, str, ", ");
-          }
-          mrb_str_cat2(mrb, str, mrb_sym2name(mrb, id));
-          mrb_str_cat2(mrb, str, "=");
-          mrb_str_append(mrb, str, mrb_inspect(mrb, value));
-        }
-      }
-    }
-  }
-  mrb_str_cat2(mrb, str, ">");
-  RSTRING_PTR(str)[0] = '#';
-
-  return str;
-}
-
 int
 mrb_obj_basic_to_s_p(mrb_state *mrb, mrb_value obj)
 {
     struct RProc *me = mrb_method_search(mrb, mrb_class(mrb, obj), mrb_intern(mrb, "to_s"));
     if (me && MRB_PROC_CFUNC_P(me) && (me->body.func == mrb_any_to_s))
-      return 1;
-    return 0;
+      return TRUE;
+    return FALSE;
 }
 
 /* 15.3.1.3.17 */
@@ -96,16 +59,7 @@ mrb_value
 mrb_obj_inspect(mrb_state *mrb, mrb_value obj)
 {
   if ((mrb_type(obj) == MRB_TT_OBJECT) && mrb_obj_basic_to_s_p(mrb, obj)) {
-    long len = ROBJECT_NUMIV(obj);
-
-    if (len > 0) {
-      mrb_value str;
-      const char *c = mrb_obj_classname(mrb, obj);
-
-      str = mrb_sprintf(mrb, "-<%s:%p", c, (void*)&obj);
-      return inspect_obj(mrb, obj, str, 0);
-    }
-    return mrb_any_to_s(mrb, obj);
+    return mrb_obj_iv_inspect(mrb, mrb_obj_ptr(obj));
   }
   else if (mrb_nil_p(obj)) {
     return mrb_str_new(mrb, "nil", 3);
@@ -347,13 +301,7 @@ init_copy(mrb_state *mrb, mrb_value dest, mrb_value obj)
       case MRB_TT_OBJECT:
       case MRB_TT_CLASS:
       case MRB_TT_MODULE:
-        if (ROBJECT(dest)->iv) {
-            kh_destroy(iv, ROBJECT(dest)->iv);
-            ROBJECT(dest)->iv = 0;
-        }
-        if (ROBJECT(obj)->iv) {
-            ROBJECT(dest)->iv = kh_copy(iv, mrb, ROBJECT(obj)->iv);
-        }
+	mrb_iv_copy(mrb, dest, obj);
         break;
 
       default:
@@ -597,6 +545,18 @@ obj_is_instance_of(mrb_state *mrb, mrb_value self)
   }
 }
 
+static void
+check_iv_name(mrb_state *mrb, mrb_sym id)
+{
+  const char *s;
+  int len;
+
+  s = mrb_sym2name_len(mrb, id, &len);
+  if (len < 2 && s[0] != '@') {
+    mrb_name_error(mrb, id, "`%s' is not allowed as an instance variable name", s);
+  }
+}
+
 /* 15.3.1.3.20 */
 /*
  *  call-seq:
@@ -618,20 +578,12 @@ obj_is_instance_of(mrb_state *mrb, mrb_value self)
 mrb_value
 mrb_obj_ivar_defined(mrb_state *mrb, mrb_value self)
 {
-  mrb_value arg;
-  khiter_t k;
-  kh_iv_t *h = RCLASS_IV_TBL(self);
   mrb_sym mid;
 
-  mrb_get_args(mrb, "o", &arg);
-  mid = mrb_to_id(mrb, arg);
-
-  if (h) {
-    k = kh_get(iv, h, mid);
-    if (k != kh_end(h)) {
-      return mrb_true_value();
-    }
-  }
+  mrb_get_args(mrb, "n", &mid);
+  check_iv_name(mrb, mid);
+  if (mrb_obj_iv_defined(mrb, mrb_obj_ptr(self), mid))
+    return mrb_true_value();
   return mrb_false_value();
 }
 
@@ -658,15 +610,11 @@ mrb_obj_ivar_defined(mrb_state *mrb, mrb_value self)
 mrb_value
 mrb_obj_ivar_get(mrb_state *mrb, mrb_value self)
 {
-  mrb_value arg;
   mrb_sym id;
 
-  mrb_get_args(mrb, "o", &arg);
-  id = mrb_to_id(mrb, arg);
+  mrb_get_args(mrb, "n", &id);
 
-  //if (!mrb_is_instance_id(id)) {
-  //    mrb_name_error(mrb, id, "`%s' is not allowed as an instance variable name", mrb_sym2name(mrb, id));
-  //}
+  check_iv_name(mrb, id);
   return mrb_iv_get(mrb, self, id);
 }
 
@@ -693,12 +641,11 @@ mrb_obj_ivar_get(mrb_state *mrb, mrb_value self)
 mrb_value
 mrb_obj_ivar_set(mrb_state *mrb, mrb_value self)
 {
-  mrb_value key;
-  mrb_value val;
   mrb_sym id;
+  mrb_value val;
 
-  mrb_get_args(mrb, "oo", &key, &val);
-  id = mrb_to_id(mrb, key);
+  mrb_get_args(mrb, "no", &id, &val);
+  check_iv_name(mrb, id);
   mrb_iv_set(mrb, self, id, val);
   return val;
 }
@@ -1011,6 +958,7 @@ mrb_obj_remove_instance_variable(mrb_state *mrb, mrb_value self)
   mrb_value val;
 
   mrb_get_args(mrb, "n", &sym);
+  check_iv_name(mrb, sym);
   val = mrb_iv_remove(mrb, self, sym);
   if (mrb_undef_p(val)) {
     mrb_name_error(mrb, sym, "instance variable %s not defined", mrb_sym2name(mrb, sym));
diff --git a/src/object.c b/src/object.c
index 26df48afd..20310d288 100644
--- a/src/object.c
+++ b/src/object.c
@@ -14,7 +14,7 @@
 int
 mrb_obj_eq(mrb_state *mrb, mrb_value v1, mrb_value v2)
 {
-  if (v1.tt != v2.tt) return 0;
+  if (v1.tt != v2.tt) return FALSE;
   switch (v1.tt) {
   case MRB_TT_TRUE:
     return 1;
@@ -498,10 +498,10 @@ mrb_obj_is_kind_of(mrb_state *mrb, mrb_value obj, struct RClass *c)
 
   while (cl) {
     if (cl == c || cl->mt == c->mt)
-      return 1/* TRUE */;
+      return TRUE;
     cl = cl->super;
   }
-  return 0/* FALSE */;
+  return FALSE;
 }
 
 static mrb_value
diff --git a/src/pool.c b/src/pool.c
index daa6d0f69..71e4b477d 100644
--- a/src/pool.c
+++ b/src/pool.c
@@ -123,7 +123,7 @@ mrb_pool_can_realloc(mrb_pool *pool, void *p, size_t len)
 {
   struct mrb_pool_page *page;
 
-  if (!pool) return 0;
+  if (!pool) return FALSE;
   len += ALIGN_PADDING(len);
   page = pool->pages;
   while (page) {
@@ -131,12 +131,12 @@ mrb_pool_can_realloc(mrb_pool *pool, void *p, size_t len)
       size_t beg;
 
       beg = (char*)p - page->page;
-      if (beg + len > page->len) return 0;
-      return 1;
+      if (beg + len > page->len) return FALSE;
+      return TRUE;
     }
     page = page->next;
   }
-  return 0;
+  return FALSE;
 }
 
 void*
diff --git a/src/state.c b/src/state.c
index 26e7dff4a..181cd00e0 100644
--- a/src/state.c
+++ b/src/state.c
@@ -6,6 +6,7 @@
 
 #include "mruby.h"
 #include "mruby/irep.h"
+#include "mruby/variable.h"
 #include <string.h>
 
 void mrb_init_heap(mrb_state*);
@@ -54,6 +55,7 @@ mrb_close(mrb_state *mrb)
   int i;
 
   /* free */
+  mrb_gc_free_gv(mrb);
   mrb_free(mrb, mrb->stbase);
   mrb_free(mrb, mrb->cibase);
   for (i=0; i<mrb->irep_len; i++) {
diff --git a/src/string.c b/src/string.c
index aef0ac88f..b749614dc 100644
--- a/src/string.c
+++ b/src/string.c
@@ -2296,7 +2296,7 @@ mrb_block_given_p()
 {
   /*if (ruby_frame->iter == ITER_CUR && ruby_block)
     return 1;*//*Qtrue*/
-  return 0/*Qfalse*/;
+  return FALSE;
 }
 
 /* 15.2.10.5.37 */
diff --git a/src/struct.c b/src/struct.c
index beb7c2f46..a5ffe6453 100644
--- a/src/struct.c
+++ b/src/struct.c
@@ -368,30 +368,35 @@ mrb_struct_s_def(mrb_state *mrb, mrb_value klass)
   name = mrb_nil_value();
   rest = mrb_nil_value();
   mrb_get_args(mrb, "*&", &argv, &argc, &b);
-  if (argc > 0) name = argv[0];
-  if (argc > 1) rest = argv[1];
-  if (mrb_type(rest) == MRB_TT_ARRAY) {
-    if (!mrb_nil_p(name) && SYMBOL_P(name)) {
-      /* 1stArgument:symbol -> name=nil rest=argv[0]-[n] */
-      mrb_ary_unshift(mrb, rest, name);
-      name = mrb_nil_value();
+  if (argc == 0) { /* special case to avoid crash */
+    rest = mrb_ary_new(mrb);
+  } 
+  else {   
+    if (argc > 0) name = argv[0];
+    if (argc > 1) rest = argv[1];
+    if (mrb_type(rest) == MRB_TT_ARRAY) {
+      if (!mrb_nil_p(name) && SYMBOL_P(name)) {
+        /* 1stArgument:symbol -> name=nil rest=argv[0]-[n] */
+        mrb_ary_unshift(mrb, rest, name);
+        name = mrb_nil_value();
+      }
     }
-  }
-  else {
-    pargv = &argv[1];
-    argcnt = argc-1;
-    if (!mrb_nil_p(name) && SYMBOL_P(name)) {
-      /* 1stArgument:symbol -> name=nil rest=argv[0]-[n] */
-      name = mrb_nil_value();
-      pargv = &argv[0];
-      argcnt++;
+    else {
+      pargv = &argv[1];
+      argcnt = argc-1;
+      if (!mrb_nil_p(name) && SYMBOL_P(name)) {
+        /* 1stArgument:symbol -> name=nil rest=argv[0]-[n] */
+        name = mrb_nil_value();
+        pargv = &argv[0];
+        argcnt++;
+      }
+      rest = mrb_ary_new_from_values(mrb, argcnt, pargv);
     }
-    rest = mrb_ary_new_from_values(mrb, argcnt, pargv);
-  }
-  for (i=0; i<RARRAY_LEN(rest); i++) {
-    id = mrb_to_id(mrb, RARRAY_PTR(rest)[i]);
-    RARRAY_PTR(rest)[i] = mrb_symbol_value(id);
-  }
+    for (i=0; i<RARRAY_LEN(rest); i++) {
+      id = mrb_to_id(mrb, RARRAY_PTR(rest)[i]);
+      RARRAY_PTR(rest)[i] = mrb_symbol_value(id);
+    }
+  }  
   st = make_struct(mrb, name, rest, struct_class(mrb));
   if (!mrb_nil_p(b)) {
     mrb_funcall(mrb, b, "call", 1, &st);
diff --git a/src/symbol.c b/src/symbol.c
index b81296929..6b29ed350 100644
--- a/src/symbol.c
+++ b/src/symbol.c
@@ -236,7 +236,7 @@ is_special_global_name(const char* m)
         if (is_identchar(*m)) m += 1;
         break;
       default:
-        if (!ISDIGIT(*m)) return 0;
+        if (!ISDIGIT(*m)) return FALSE;
         do ++m; while (ISDIGIT(*m));
     }
     return !*m;
@@ -404,4 +404,5 @@ mrb_init_symbol(mrb_state *mrb)
   mrb_define_method(mrb, sym, "to_sym",          sym_to_sym,              ARGS_NONE());              /* 15.2.11.3.4  */
   mrb_define_method(mrb, sym, "inspect",         sym_inspect,             ARGS_NONE());              /* 15.2.11.3.5(x)  */
   mrb_define_method(mrb, sym, "<=>",             sym_cmp,                 ARGS_REQ(1));
+  mrb->init_sym = mrb_intern(mrb, "initialize");
 }
diff --git a/src/variable.c b/src/variable.c
index 8b94f5bbb..618e8cb89 100644
--- a/src/variable.c
+++ b/src/variable.c
@@ -6,29 +6,374 @@
 
 #include "mruby.h"
 #include "mruby/class.h"
-#include "mruby/khash.h"
 #include "mruby/variable.h"
 #include "error.h"
 #include "mruby/array.h"
+#include "mruby/string.h"
 #include "mruby/proc.h"
+#ifndef MRB_USE_IV_SEGLIST
+#include "mruby/khash.h"
+#endif
 
 #ifdef ENABLE_REGEXP
 #include "re.h"
 #endif
 
+typedef int (iv_foreach_func)(mrb_state*,mrb_sym,mrb_value,void*);
+
+#ifdef MRB_USE_IV_SEGLIST
+
+#ifndef MRB_SEGMENT_SIZE
+#define MRB_SEGMENT_SIZE 4
+#endif
+
+typedef struct segment
+{
+  mrb_sym key[MRB_SEGMENT_SIZE];
+  mrb_value val[MRB_SEGMENT_SIZE];
+  struct segment *next;
+} segment;
+
+typedef struct iv_tbl {
+  segment *rootseg;
+  int size;
+  int last_len;
+} iv_tbl;
+
+static iv_tbl*
+iv_new(mrb_state *mrb)
+{
+  iv_tbl *t;
+
+  t = mrb_malloc(mrb, sizeof(iv_tbl));
+  if (t) {
+    t->size = 0;
+    t->rootseg =  NULL;
+    t->last_len = 0;
+  }
+  return t;
+}
+
+static void
+iv_put(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value val)
+{
+  segment *seg = t->rootseg;
+  segment *prev = NULL;
+  segment *matched_seg = NULL;
+  int matched_idx = 0;
+  int i;
+
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+      /* found room in last segment after last_len */
+      if (!seg->next && i >= t->last_len) {
+	seg->key[i] = sym;
+	seg->val[i] = val;
+	t->last_len = i+1;
+	t->size++;
+	return;
+      }
+      if (key == 0 && !matched_seg) {
+	matched_seg = seg;
+	matched_idx = i;
+      }
+      else if (key == sym) {
+        seg->val[i] = val;
+        return;
+      }
+    }
+    prev = seg;
+    seg = seg->next;
+  }
+
+  /* not found */
+  t->size++;
+  if (matched_seg) {
+    matched_seg->key[matched_idx] = sym;
+    matched_seg->val[matched_idx] = val;
+    return;
+  }
+
+  seg = mrb_malloc(mrb, sizeof(segment));
+  if (!seg) return;
+  seg->next = NULL;
+  seg->key[0] = sym;
+  seg->val[0] = val;
+  t->last_len = 1;
+  if (prev) {
+    prev->next = seg;
+  }
+  else {
+    t->rootseg = seg;
+  }
+  return;
+}
+
+static int
+iv_get(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  segment *seg;
+  int i;
+
+  seg = t->rootseg;
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+
+      if (!seg->next && i >= t->last_len) {
+	return FALSE;
+      }
+      if (key == sym) {
+	if (vp) *vp = seg->val[i];
+	return TRUE;
+      }
+    }
+    seg = seg->next;
+  }
+  return FALSE;
+}
+
+static int
+iv_del(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  segment *seg;
+  int i;
+
+  seg = t->rootseg;
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+
+      if (!seg->next && i >= t->last_len) {
+	return FALSE;
+      }
+      if (key == sym) {
+	t->size--;
+	seg->key[i] = 0;
+	if (vp) *vp = seg->val[i];
+	return TRUE;
+      }
+    }
+    seg = seg->next;
+  }
+  return FALSE;
+}
+
+static int
+iv_foreach(mrb_state *mrb, iv_tbl *t, iv_foreach_func *func, void *p)
+{
+  segment *seg;
+  int i, n;
+
+  seg = t->rootseg;
+  while (seg) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+
+      /* no value in last segment after last_len */
+      if (!seg->next && i >= t->last_len) {
+	return FALSE;
+      }
+      if (key != 0) {
+	n =(*func)(mrb, key, seg->val[i], p);
+	if (n > 0) return FALSE;
+	if (n < 0) {
+	  t->size--;
+	  seg->key[i] = 0;
+	}
+      }
+    }
+    seg = seg->next;
+  }
+  return TRUE;
+}
+
+static int
+iv_size(mrb_state *mrb, iv_tbl *t)
+{
+  segment *seg;
+  int size = 0;
+
+  if (!t) return 0;
+  if (t->size > 0) return t->size;
+  seg = t->rootseg;
+  while (seg) {
+    if (seg->next == NULL) {
+      size += t->last_len;
+      return size;
+    }
+    seg = seg->next;
+    size += MRB_SEGMENT_SIZE;
+  }
+  /* empty iv_tbl */
+  return 0;
+}
+
+static iv_tbl*
+iv_copy(mrb_state *mrb, iv_tbl *t)
+{
+  segment *seg;
+  iv_tbl *t2;
+
+  int i;
+
+  seg = t->rootseg;
+  t2 = iv_new(mrb);
+
+  while (seg != NULL) {
+    for (i=0; i<MRB_SEGMENT_SIZE; i++) {
+      mrb_sym key = seg->key[i];
+      mrb_value val = seg->val[i];
+
+      iv_put(mrb, t2, key, val);
+      if ((seg->next == NULL) && (i >= t->last_len)) {
+        return t2;
+      }
+    }
+    seg = seg->next;
+  }
+  return t2;
+}
+
+static void
+iv_free(mrb_state *mrb, iv_tbl *t)
+{
+  segment *seg;
+
+  seg = t->rootseg;
+  while (seg) {
+    segment *p = seg;
+    seg = seg->next;
+    mrb_free(mrb, p);
+  }
+  mrb_free(mrb, t);
+}
+
+#else
+
+#include "mruby/khash.h"
+
 #ifndef MRB_IV_INITIAL_SIZE
 #define MRB_IV_INITIAL_SIZE 8
 #endif
 
+KHASH_DECLARE(iv, mrb_sym, mrb_value, 1)
+KHASH_DEFINE(iv, mrb_sym, mrb_value, 1, kh_int_hash_func, kh_int_hash_equal);
+
+typedef struct iv_tbl {
+  khash_t(iv) h;
+} iv_tbl;
+
+static iv_tbl*
+iv_new(mrb_state *mrb)
+{
+  return (iv_tbl*)kh_init_size(iv, mrb, MRB_IV_INITIAL_SIZE);
+}
+
 static void
-mark_tbl(mrb_state *mrb, struct kh_iv *h)
+iv_put(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value val)
 {
+  khash_t(iv) *h = &t->h;
   khiter_t k;
 
-  if (!h) return;
-  for (k = kh_begin(h); k != kh_end(h); k++)
-    if (kh_exist(h, k))
-      mrb_gc_mark_value(mrb, kh_value(h, k));
+  k = kh_put(iv, h, sym);
+  kh_value(h, k) = val;
+}
+
+static int
+iv_get(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+
+  k = kh_get(iv, h, sym);
+  if (k != kh_end(h)) {
+    if (vp) *vp = kh_value(h, k);
+    return TRUE;
+  }
+  return FALSE;
+}
+
+static int
+iv_del(mrb_state *mrb, iv_tbl *t, mrb_sym sym, mrb_value *vp)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+
+  if (h) {
+    k = kh_get(iv, h, sym);
+    if (k != kh_end(h)) {
+      mrb_value val = kh_value(h, k);
+      kh_del(iv, h, k);
+      if (vp) *vp = val;
+      return TRUE;
+    }
+  }
+  return FALSE;
+}
+
+static int
+iv_foreach(mrb_state *mrb, iv_tbl *t, iv_foreach_func *func, void *p)
+{
+  khash_t(iv) *h = &t->h;
+  khiter_t k;
+  int n;
+
+  if (h) {
+    for (k = kh_begin(h); k != kh_end(h); k++) {
+      if (kh_exist(h, k)){
+	n = (*func)(mrb, kh_key(h, k), kh_value(h, k), p);
+	if (n > 0) return FALSE;
+	if (n < 0) {
+	  kh_del(iv, h, k);
+	}
+      }
+    }
+  }
+  return TRUE;
+}
+
+static int
+iv_size(mrb_state *mrb, iv_tbl *t)
+{
+  khash_t(iv) *h = &t->h;
+
+  if (!h) return 0;
+  return kh_size(h);
+}
+
+static iv_tbl*
+iv_copy(mrb_state *mrb, iv_tbl *t)
+{
+  return (iv_tbl*)kh_copy(iv, mrb, &t->h);
+}
+
+static void
+iv_free(mrb_state *mrb, iv_tbl *t)
+{
+  kh_destroy(iv, &t->h);
+}
+
+#endif
+
+#ifndef MRB_IV_INITIAL_SIZE
+#define MRB_IV_INITIAL_SIZE 8
+#endif
+
+static int
+iv_mark_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_gc_mark_value(mrb, v);
+  return 0;
+}
+
+static void
+mark_tbl(mrb_state *mrb, iv_tbl *t)
+{
+  if (t) {
+    iv_foreach(mrb, t, iv_mark_i, 0);
+  }
 }
 
 void
@@ -40,7 +385,8 @@ mrb_gc_mark_gv(mrb_state *mrb)
 void
 mrb_gc_free_gv(mrb_state *mrb)
 {
-  kh_destroy(iv, mrb->globals);
+  if (mrb->globals)
+    iv_free(mrb, mrb->globals);
 }
 
 void
@@ -52,16 +398,15 @@ mrb_gc_mark_iv(mrb_state *mrb, struct RObject *obj)
 size_t
 mrb_gc_mark_iv_size(mrb_state *mrb, struct RObject *obj)
 {
-  struct kh_iv *h = obj->iv;
-
-  if (!h) return 0;
-  return kh_size(h);
+  return iv_size(mrb, obj->iv);
 }
 
 void
 mrb_gc_free_iv(mrb_state *mrb, struct RObject *obj)
 {
-  kh_destroy(iv, obj->iv);
+  if (obj->iv) {
+    iv_free(mrb, obj->iv);
+  }
 }
 
 mrb_value
@@ -75,26 +420,6 @@ mrb_vm_special_set(mrb_state *mrb, mrb_sym i, mrb_value v)
 {
 }
 
-static mrb_value
-ivget(mrb_state *mrb, struct kh_iv *h, mrb_sym sym)
-{
-  khiter_t k;
-
-  k = kh_get(iv, h, sym);
-  if (k != kh_end(h))
-    return kh_value(h, k);
-  return mrb_nil_value();
-}
-
-mrb_value
-mrb_obj_iv_get(mrb_state *mrb, struct RObject *obj, mrb_sym sym)
-{
-  if (!obj->iv) {
-    return mrb_nil_value();
-  }
-  return ivget(mrb, obj->iv, sym);
-}
-
 static int
 obj_iv_p(mrb_value obj)
 {
@@ -111,6 +436,16 @@ obj_iv_p(mrb_value obj)
 }
 
 mrb_value
+mrb_obj_iv_get(mrb_state *mrb, struct RObject *obj, mrb_sym sym)
+{
+  mrb_value v;
+
+  if (obj->iv && iv_get(mrb, obj->iv, sym, &v))
+    return v;
+  return mrb_nil_value();
+}
+
+mrb_value
 mrb_iv_get(mrb_state *mrb, mrb_value obj, mrb_sym sym)
 {
   if (obj_iv_p(obj)) {
@@ -119,54 +454,110 @@ mrb_iv_get(mrb_state *mrb, mrb_value obj, mrb_sym sym)
   return mrb_nil_value();
 }
 
-static void
-ivset(mrb_state *mrb, struct kh_iv *h, mrb_sym sym, mrb_value v)
+void
+mrb_obj_iv_set(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v)
 {
-  khiter_t k;
+  iv_tbl *t = obj->iv;
 
-  k = kh_put(iv, h, sym);
-  kh_value(h, k) = v;
+  if (!t) {
+    t = obj->iv = iv_new(mrb);
+  }
+  mrb_write_barrier(mrb, (struct RBasic*)obj);
+  iv_put(mrb, t, sym, v);
 }
 
 void
-mrb_obj_iv_set(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v)
+mrb_iv_set(mrb_state *mrb, mrb_value obj, mrb_sym sym, mrb_value v)
 {
-  khash_t(iv) *h;
-
-  if (!obj->iv) {
-    h = obj->iv = kh_init_size(iv, mrb, MRB_IV_INITIAL_SIZE);
+  if (obj_iv_p(obj)) {
+    mrb_obj_iv_set(mrb, mrb_obj_ptr(obj), sym, v);
   }
   else {
-    h = obj->iv;
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "cannot set instance variable");
   }
-  mrb_write_barrier(mrb, (struct RBasic*)obj);
-  ivset(mrb, h, sym, v);
+}
+
+int
+mrb_obj_iv_defined(mrb_state *mrb, struct RObject *obj, mrb_sym sym)
+{
+  iv_tbl *t;
+
+  t = obj->iv;
+  if (t) {
+    return iv_get(mrb, t, sym, NULL);
+  }
+  return FALSE;
+}
+
+int
+mrb_iv_defined(mrb_state *mrb, mrb_value obj, mrb_sym sym)
+{
+  if (!obj_iv_p(obj)) return FALSE;
+  return mrb_obj_iv_defined(mrb, mrb_obj_ptr(obj), sym);
 }
 
 void
-mrb_iv_set(mrb_state *mrb, mrb_value obj, mrb_sym sym, mrb_value v) /* mrb_ivar_set */
+mrb_iv_copy(mrb_state *mrb, mrb_value dest, mrb_value src)
 {
-  if (obj_iv_p(obj)) {
-    mrb_obj_iv_set(mrb, mrb_obj_ptr(obj), sym, v);
+  struct RObject *d = mrb_obj_ptr(dest);
+  struct RObject *s = mrb_obj_ptr(src);
+
+  if (d->iv) {
+    iv_free(mrb, d->iv);
+    d->iv = 0;
   }
+  if (s->iv) {
+    d->iv = iv_copy(mrb, s->iv);
+  }
+}
+
+static int
+inspect_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value str = *(mrb_value*)p;
+  const char *s;
+  int len;
+
+  /* need not to show internal data */
+  if (RSTRING_PTR(str)[0] == '-') { /* first element */
+    RSTRING_PTR(str)[0] = '#';
+    mrb_str_cat2(mrb, str, " ");
+  }
+  else {
+    mrb_str_cat2(mrb, str, ", ");
+  }
+  s = mrb_sym2name_len(mrb, sym, &len);
+  mrb_str_cat(mrb, str, s, len);
+  mrb_str_cat(mrb, str, "=", 1);
+  mrb_str_append(mrb, str, mrb_inspect(mrb, v));
+  return 0;
 }
 
 mrb_value
-mrb_iv_remove(mrb_state *mrb, mrb_value obj, mrb_sym sym)
+mrb_obj_iv_inspect(mrb_state *mrb, struct RObject *obj)
 {
-  mrb_value val;
+  iv_tbl *t = obj->iv;
+  int len = iv_size(mrb, t);
 
+  if (len > 0) {
+    const char *cn = mrb_obj_classname(mrb, mrb_obj_value(obj));
+    mrb_value str = mrb_sprintf(mrb, "-<%s:%p", cn, (void*)obj);
+
+    iv_foreach(mrb, t, inspect_i, &str);
+    return str;
+  }
+  return mrb_any_to_s(mrb, mrb_obj_value(obj));
+}
+
+mrb_value
+mrb_iv_remove(mrb_state *mrb, mrb_value obj, mrb_sym sym)
+{
   if (obj_iv_p(obj)) {
-    khash_t(iv) *h = mrb_obj_ptr(obj)->iv;
-    khiter_t k;
-
-    if (h) {
-      k = kh_get(iv, h, sym);
-      if (k != kh_end(h)) {
-	val = kh_value(h, k);
-	kh_del(iv, h, k);
-	return val;
-      }
+    iv_tbl *t = mrb_obj_ptr(obj)->iv;
+    mrb_value val;
+
+    if (iv_del(mrb, t, sym, &val)) {
+      return val;
     }
   }
   return mrb_undef_value();
@@ -186,6 +577,21 @@ mrb_vm_iv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
   mrb_iv_set(mrb, mrb->stack[0], sym, v);
 }
 
+static int
+iv_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value ary;
+  const char* s;
+  int len;
+
+  ary = *(mrb_value*)p;
+  s = mrb_sym2name_len(mrb, sym, &len);
+  if (len > 1 && s[0] == '@') {
+    mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
+  }
+  return 0;
+}
+
 /* 15.3.1.3.23 */
 /*
  *  call-seq:
@@ -207,25 +613,10 @@ mrb_value
 mrb_obj_instance_variables(mrb_state *mrb, mrb_value self)
 {
   mrb_value ary;
-  kh_iv_t *h;
-  khint_t i;
-  int len;
-  const char* p;
 
   ary = mrb_ary_new(mrb);
-  if (obj_iv_p(self)) {
-    h = ROBJECT_IVPTR(self);
-    if (h) {
-      for (i=0;i<kh_end(h);i++) {
-        if (kh_exist(h, i)) {
-          p = mrb_sym2name_len(mrb, kh_key(h,i), &len);
-          if (len > 1 && *p == '@') {
-            if (mrb_type(kh_value(h, i)) != MRB_TT_UNDEF)
-              mrb_ary_push(mrb, ary, mrb_str_new(mrb, p, len));
-          }
-        }
-      }
-    }
+  if (obj_iv_p(self) && mrb_obj_ptr(self)->iv) {
+    iv_foreach(mrb, mrb_obj_ptr(self)->iv, iv_i, &ary);
   }
   return ary;
 }
@@ -238,11 +629,11 @@ mrb_vm_cv_get(mrb_state *mrb, mrb_sym sym)
   if (!c) c = mrb->ci->target_class;
   while (c) {
     if (c->iv) {
-      khash_t(iv) *h = c->iv;
-      khiter_t k = kh_get(iv, h, sym);
+      iv_tbl *t = c->iv;
+      mrb_value v;
 
-      if (k != kh_end(h))
-        return kh_value(h, k);
+      if (iv_get(mrb, t, sym, &v))
+	return v;
     }
     c = c->super;
   }
@@ -253,43 +644,34 @@ void
 mrb_vm_cv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
 {
   struct RClass *c = mrb->ci->proc->target_class;
-  khash_t(iv) *h;
-  khiter_t k;
 
   if (!c) c = mrb->ci->target_class;
   while (c) {
     if (c->iv) {
-      h = c->iv;
-      k = kh_get(iv, h, sym);
-      if (k != kh_end(h)) {
-        k = kh_put(iv, h, sym);
-        kh_value(h, k) = v;
+      iv_tbl *t = c->iv;
+
+      if (iv_get(mrb, t, sym, NULL)) {
+	iv_put(mrb, t, sym, v);
         return;
       }
     }
     c = c->super;
   }
   c = mrb->ci->target_class;
-  h = c->iv;
-  if (!h) {
-    c->iv = h = kh_init_size(iv, mrb, MRB_IV_INITIAL_SIZE);
+  if (!c->iv) {
+    c->iv = iv_new(mrb);
   }
-  k = kh_put(iv, h, sym);
-  kh_value(h, k) = v;
+  iv_put(mrb, c->iv, sym, v);
 }
 
 int
 mrb_const_defined(mrb_state *mrb, mrb_value mod, mrb_sym sym)
 {
-  khiter_t k;
   struct RClass *m = mrb_class_ptr(mod);
-  struct kh_iv *h = m->iv;
+  iv_tbl *t = m->iv;
 
-  if (!h) return 0;
-  k = kh_get(iv, h, sym);
-  if (k != kh_end(h))
-    return 1;
-  return 0;
+  if (!t) return FALSE;
+  return iv_get(mrb, t, sym, NULL);
 }
 
 static void
@@ -309,19 +691,17 @@ static mrb_value
 const_get(mrb_state *mrb, struct RClass *base, mrb_sym sym)
 {
   struct RClass *c = base;
-  khash_t(iv) *h;
-  khiter_t k;
+  mrb_value v;
+  iv_tbl *t;
   int retry = 0;
   mrb_sym cm;
 
  L_RETRY:
   while (c) {
     if (c->iv) {
-      h = c->iv;
-      k = kh_get(iv, h, sym);
-      if (k != kh_end(h)) {
-        return kh_value(h, k);
-      }
+      t = c->iv;
+      if (iv_get(mrb, t, sym, &v))
+	return v;
     }
     c = c->super;
   }
@@ -374,13 +754,13 @@ mrb_vm_const_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
   struct RClass *c = mrb->ci->proc->target_class;
 
   if (!c) c = mrb->ci->target_class;
-  mrb_obj_iv_set(mrb, (struct RObject*)c, sym, v);
+  mrb_iv_set(mrb, mrb_obj_value(c), sym, v);
 }
 
 void
 mrb_define_const(mrb_state *mrb, struct RClass *mod, const char *name, mrb_value v)
 {
-  mrb_obj_iv_set(mrb, (struct RObject*)mod, mrb_intern(mrb, name), v);
+  mrb_iv_set(mrb, mrb_obj_value(mod), mrb_intern(mrb, name), v);
 }
 
 void
@@ -392,24 +772,38 @@ mrb_define_global_const(mrb_state *mrb, const char *name, mrb_value val)
 mrb_value
 mrb_gv_get(mrb_state *mrb, mrb_sym sym)
 {
+  mrb_value v;
+
   if (!mrb->globals) {
     return mrb_nil_value();
   }
-  return ivget(mrb, mrb->globals, sym);
+  if (iv_get(mrb, mrb->globals, sym, &v))
+    return v;
+  return mrb_nil_value();
 }
 
 void
 mrb_gv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
 {
-  khash_t(iv) *h;
+  iv_tbl *t;
 
   if (!mrb->globals) {
-    h = mrb->globals = kh_init(iv, mrb);
+    t = mrb->globals = iv_new(mrb);
   }
   else {
-    h = mrb->globals;
+    t = mrb->globals;
   }
-  ivset(mrb, h, sym, v);
+  iv_put(mrb, t, sym, v);
+}
+
+static int
+gv_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  mrb_value ary;
+
+  ary = *(mrb_value*)p;
+  mrb_ary_push(mrb, ary, mrb_symbol_value(sym));
+  return 0;
 }
 
 /* 15.3.1.2.4  */
@@ -425,73 +819,34 @@ mrb_gv_set(mrb_state *mrb, mrb_sym sym, mrb_value v)
 mrb_value
 mrb_f_global_variables(mrb_state *mrb, mrb_value self)
 {
-  char buf[3];
-  khint_t i;
-  struct kh_iv *h = mrb->globals;
+  iv_tbl *t = mrb->globals;
   mrb_value ary = mrb_ary_new(mrb);
+  int i;
+  char buf[3];
 
-  if (h) {
-    for (i=0;i < kh_end(h);i++) {
-      if (kh_exist(h, i)) {
-        mrb_ary_push(mrb, ary, mrb_symbol_value(kh_key(h,i)));
-      }
-    }
+  if (t) {
+    iv_foreach(mrb, t, gv_i, &ary);
   }
   buf[0] = '$';
   buf[2] = 0;
   for (i = 1; i <= 9; ++i) {
-      buf[1] = (char)(i + '0');
-      mrb_ary_push(mrb, ary, mrb_symbol_value(mrb_intern(mrb, buf)));
+    buf[1] = (char)(i + '0');
+    mrb_ary_push(mrb, ary, mrb_symbol_value(mrb_intern2(mrb, buf, 2)));
   }
   return ary;
 }
 
-int
-mrb_st_lookup(struct kh_iv *table, mrb_sym id, khiter_t *value)
-{
-  khash_t(iv) *h;
-  khiter_t k;
-
-  if (table) {
-    h = (khash_t(iv)*)table;
-    k = kh_get(iv, h, id);
-    if (k != kh_end(h)) {
-      if (value != 0)  *value = k;//kh_value(h, k);
-      return 1;/* TRUE */
-    }
-    return 0;/* FALSE */
-  }
-  else {
-    return 0;/* FALSE */
-  }
-}
-
-static int
-kiv_lookup(khash_t(iv)* table, mrb_sym key, mrb_value *value)
-{
-  khash_t(iv) *h=table;
-  khiter_t k;
-
-  k = kh_get(iv, h, key);
-  if (k != kh_end(h)) {
-    *value = kh_value(h, k);
-    return 1;
-  }
-  return 0;
-}
-
 static int
 mrb_const_defined_0(mrb_state *mrb, struct RClass *klass, mrb_sym id, int exclude, int recurse)
 {
-  mrb_value value;
   struct RClass * tmp;
   int mod_retry = 0;
 
   tmp = klass;
 retry:
   while (tmp) {
-    if (tmp->iv && kiv_lookup(tmp->iv, id, &value)) {
-      return (int)1/*Qtrue*/;
+    if (tmp->iv && iv_get(mrb, tmp->iv, id, NULL)) {
+      return TRUE;
     }
     if (!recurse && (klass != mrb->object_class)) break;
     tmp = tmp->super;
@@ -501,7 +856,7 @@ retry:
     tmp = mrb->object_class;
     goto retry;
   }
-  return (int)0/*Qfalse*/;
+  return FALSE;
 }
 
 int
@@ -525,3 +880,38 @@ mrb_class_obj_get(mrb_state *mrb, const char *name)
   return mrb_class_ptr(mrb_const_get(mrb, mod, sym));
 }
 
+struct csym_arg {
+  struct RClass *c;
+  mrb_sym sym;
+};
+
+static int
+csym_i(mrb_state *mrb, mrb_sym sym, mrb_value v, void *p)
+{
+  struct csym_arg *a = (struct csym_arg*)p;
+  struct RClass *c = a->c;
+
+  if (mrb_type(v) == c->tt && mrb_class_ptr(v) == c) {
+    a->sym = sym;
+    return 1;			/* stop iteration */
+  }
+  return 0;
+}
+
+mrb_sym
+mrb_class_sym(mrb_state *mrb, struct RClass *c, struct RClass *outer)
+{
+  mrb_value name;
+
+  name = mrb_obj_iv_get(mrb, (struct RObject*)c, mrb_intern(mrb, "__classid__"));
+  if (mrb_nil_p(name)) {
+    struct csym_arg arg;
+
+    arg.c = c;
+    arg.sym = 0;
+
+    iv_foreach(mrb, outer->iv, csym_i, &arg);
+    return arg.sym;
+  }
+  return SYM2ID(name);
+}
diff --git a/src/vm.c b/src/vm.c
index cbea3ee77..c27fdfbab 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -20,6 +20,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <setjmp.h>
+#include <stddef.h>
+#include <stdarg.h>
 
 #define STACK_INIT_SIZE 128
 #define CALLINFO_INIT_SIZE 32
@@ -178,6 +180,44 @@ ecall(mrb_state *mrb, int i)
   if (!mrb->exc) mrb->exc = exc;
 }
 
+#ifndef MRB_FUNCALL_ARGC_MAX
+#define MRB_FUNCALL_ARGC_MAX 16
+#endif
+
+mrb_value
+mrb_funcall(mrb_state *mrb, mrb_value self, const char *name, int argc, ...)
+{
+  mrb_sym mid = mrb_intern(mrb, name);
+  va_list ap;
+  int i;
+
+  if (argc == 0) {
+    return mrb_funcall_argv(mrb, self, mid, 0, 0);
+  }
+  else if (argc == 1) {
+    mrb_value v;
+
+    va_start(ap, argc);
+    v = va_arg(ap, mrb_value);
+    va_end(ap);
+    return mrb_funcall_argv(mrb, self, mid, 1, &v);
+  }
+  else {
+    mrb_value argv[MRB_FUNCALL_ARGC_MAX];
+
+    if (argc > MRB_FUNCALL_ARGC_MAX) {
+      mrb_raise(mrb, E_ARGUMENT_ERROR, "Too long arguments. (limit=%d)", 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_value
 mrb_funcall_with_block(mrb_state *mrb, mrb_value self, mrb_sym mid, int argc, mrb_value *argv, mrb_value blk)
 {
@@ -188,6 +228,20 @@ mrb_funcall_with_block(mrb_state *mrb, mrb_value self, mrb_sym mid, int argc, mr
   int n = mrb->ci->nregs;
   mrb_value val;
 
+  if (!mrb->jmp) {
+    jmp_buf c_jmp;
+
+    if (setjmp(c_jmp) != 0) {	/* error */
+      mrb->jmp = 0;
+      return mrb_nil_value();
+    }
+    mrb->jmp = &c_jmp;
+    /* recursive call */
+    val = mrb_funcall_with_block(mrb, self, mid, argc, argv, blk);
+    mrb->jmp = 0;
+    return val;
+  }
+
   if (argc < 0) {
     mrb_raise(mrb, E_ARGUMENT_ERROR, "negative argc for funcall (%d)", argc);
   }
@@ -402,6 +456,7 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
   int ai = mrb->arena_idx;
   jmp_buf *prev_jmp = (jmp_buf *)mrb->jmp;
   jmp_buf c_jmp;
+  ptrdiff_t ciidx = mrb->ci - mrb->cibase;
 
 #ifdef DIRECT_THREADED
   static void *optable[] = {
@@ -450,9 +505,9 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
 
     CASE(OP_MOVE) {
       /* A B    R(A) := R(B) */
-#if 0
+#if 1
       regs[GETARG_A(i)] = regs[GETARG_B(i)];
-#elif 1
+#elif 0
       int a = GETARG_A(i);
       int b = GETARG_B(i);
 
@@ -689,7 +744,7 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
       struct RProc *m;
       struct RClass *c;
       mrb_callinfo *ci;
-      mrb_value recv;
+      mrb_value recv, result;
       mrb_sym mid = syms[GETARG_B(i)];
 
       recv = regs[a];
@@ -731,7 +786,8 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
         else {
           ci->nregs = n + 2;
         }
-        mrb->stack[0] = m->body.func(mrb, recv);
+        result = m->body.func(mrb, recv);
+        mrb->stack[0] = result;
         mrb->arena_idx = ai;
         if (mrb->exc) goto L_RAISE;
         /* pop stackpos */
@@ -1027,6 +1083,10 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
         ci = mrb->ci;
 	eidx = mrb->ci->eidx;
         if (ci == mrb->cibase) goto L_STOP;
+        if (ciidx == ci - mrb->cibase){
+          mrb->jmp = prev_jmp;
+          longjmp(*(jmp_buf*)mrb->jmp, 1);
+        }
         while (ci[0].ridx == ci[-1].ridx) {
           cipop(mrb);
           ci = mrb->ci;
diff --git a/test/t/exception.rb b/test/t/exception.rb
index 0aed0e2e6..2ea319caa 100644
--- a/test/t/exception.rb
+++ b/test/t/exception.rb
@@ -253,3 +253,19 @@ assert('Exception 13') do
   end
   a == :ok
 end
+
+def exception_test14
+  UnknownConstant
+end
+
+assert('Exception 14') do
+  a = :ng
+  begin
+    send(:exception_test14)
+  rescue
+    a = :ok
+  end
+
+  a == :ok
+end
+
diff --git a/test/t/kernel.rb b/test/t/kernel.rb
index b96e85134..59d9f3df5 100644
--- a/test/t/kernel.rb
+++ b/test/t/kernel.rb
@@ -213,11 +213,18 @@ assert('Kernel#hash', '15.3.1.3.15') do
 end
 
 assert('Kernel#inspect', '15.3.1.3.17') do
-  inspect.class == String
+  s = nil.inspect
+  s.class == String and s == "nil"
 end
 
 assert('Kernel#instance_variables', '15.3.1.3.23') do
-  instance_variables.class == Array
+  o = Object.new
+  o.instance_eval do
+    @a = 11
+    @b = 12
+  end
+  ivars = o.instance_variables
+  ivars.class == Array and ivars.size == 2 and ivars.include?(:@a) and ivars.include?(:@b)
 end
 
 assert('Kernel#is_a?', '15.3.1.3.24') do
diff --git a/test/t/struct.rb b/test/t/struct.rb
index 5cf6929b8..d79b30c0e 100644
--- a/test/t/struct.rb
+++ b/test/t/struct.rb
@@ -16,6 +16,12 @@ if Object.const_defined?(:Struct)
       c.members == [:m1,:m2]
   end
 
+  # Check crash bug with Struc.new and no params.
+  assert('Struct.new', '15.2.18.3.1') do
+     c = Struct.new()
+     c.superclass == Struct and c.members == []
+  end
+
   assert('Struct#==', '15.2.18.4.1') do
     c = Struct.new(:m1, :m2)
     cc1 = c.new(1,2)