New bytecode implementation of mruby VM.

6 files changed, 846 insertions, 934 deletions

diff --git a/src/class.c b/src/class.c
index a9439d7d7..076280f3f 100644
--- a/src/class.c
+++ b/src/class.c
@@ -1953,8 +1953,8 @@ mrb_mod_alias(mrb_state *mrb, mrb_value mod)
   return mrb_nil_value();
 }
 
-static void
-undef_method(mrb_state *mrb, struct RClass *c, mrb_sym a)
+void
+mrb_undef_method_id(mrb_state *mrb, struct RClass *c, mrb_sym a)
 {
   if (!mrb_obj_respond_to(mrb, c, a)) {
     mrb_name_error(mrb, a, "undefined method '%S' for class '%S'", mrb_sym2str(mrb, a), mrb_obj_value(c));
@@ -1970,7 +1970,7 @@ undef_method(mrb_state *mrb, struct RClass *c, mrb_sym a)
 MRB_API void
 mrb_undef_method(mrb_state *mrb, struct RClass *c, const char *name)
 {
-  undef_method(mrb, c, mrb_intern_cstr(mrb, name));
+  mrb_undef_method_id(mrb, c, mrb_intern_cstr(mrb, name));
 }
 
 MRB_API void
@@ -1988,7 +1988,7 @@ mrb_mod_undef(mrb_state *mrb, mrb_value mod)
 
   mrb_get_args(mrb, "*", &argv, &argc);
   while (argc--) {
-    undef_method(mrb, c, to_sym(mrb, *argv));
+    mrb_undef_method_id(mrb, c, to_sym(mrb, *argv));
     argv++;
   }
   return mrb_nil_value();
diff --git a/src/codedump.c b/src/codedump.c
index d79a65a70..22cbc59eb 100644
--- a/src/codedump.c
+++ b/src/codedump.c
@@ -6,451 +6,503 @@
 #include <mruby/proc.h>
 
 #ifndef MRB_DISABLE_STDIO
-static int
-print_r(mrb_state *mrb, mrb_irep *irep, size_t n, int pre)
+static void
+print_r(mrb_state *mrb, mrb_irep *irep, size_t n)
 {
   size_t i;
 
-  if (n == 0) return 0;
+  if (n == 0) return;
 
   for (i=0; i+1<irep->nlocals; i++) {
     if (irep->lv[i].r == n) {
       mrb_sym sym = irep->lv[i].name;
-      if (pre) printf(" ");
-      printf("R%d:%s", (int)n, mrb_sym2name(mrb, sym));
-      return 1;
+      printf(" R%d:%s", (int)n, mrb_sym2name(mrb, sym));
     }
   }
-  return 0;
 }
 
-#define RA  1
-#define RB  2
-#define RAB 3
-
 static void
-print_lv(mrb_state *mrb, mrb_irep *irep, mrb_code c, int r)
+print_lv_a(mrb_state *mrb, mrb_irep *irep, uint16_t a)
 {
-  int pre = 0;
-
-  if (!irep->lv
-      || ((!(r & RA) || GETARG_A(c) >= irep->nlocals)
-       && (!(r & RB) || GETARG_B(c) >= irep->nlocals))) {
+  if (!irep->lv || a >= irep->nlocals || a == 0) {
     printf("\n");
     return;
   }
-  printf("\t; ");
-  if (r & RA) {
-    pre = print_r(mrb, irep, GETARG_A(c), 0);
-  }
-  if (r & RB) {
-    print_r(mrb, irep, GETARG_B(c), pre);
+  printf("\t;");
+  print_r(mrb, irep, a);
+  printf("\n");
+}
+
+static void
+print_lv_ab(mrb_state *mrb, mrb_irep *irep, uint16_t a, uint16_t b)
+{
+  if (!irep->lv || (a >= irep->nlocals && b >= irep->nlocals) || a+b == 0) {
+    printf("\n");
+    return;
   }
+  printf("\t;");
+  if (a > 0) print_r(mrb, irep, a);
+  if (b > 0) print_r(mrb, irep, b);
   printf("\n");
 }
 #endif
 
 static void
+print_header(mrb_irep *irep, int i)
+{
+  int32_t line;
+
+  line = mrb_debug_get_line(irep, i);
+  if (line < 0) {
+    printf("      ");
+  }
+  else {
+    printf("%5d ", line);
+  }
+
+  printf("%03d ", i);
+}
+
+#define CASE(insn,ops) case insn: FETCH_ ## ops (); L_ ## insn
+
+static void
 codedump(mrb_state *mrb, mrb_irep *irep)
 {
 #ifndef MRB_DISABLE_STDIO
-  int i;
   int ai;
-  mrb_code c;
+  mrb_code *pc, *pcend;
+  mrb_code ins;
   const char *file = NULL, *next_file;
-  int32_t line;
 
   if (!irep) return;
   printf("irep %p nregs=%d nlocals=%d pools=%d syms=%d reps=%d\n", (void*)irep,
          irep->nregs, irep->nlocals, (int)irep->plen, (int)irep->slen, (int)irep->rlen);
 
-  for (i = 0; i < (int)irep->ilen; i++) {
+  pc = irep->iseq;
+  pcend = pc + irep->ilen;
+  while (pc < pcend) {
+    int i;
+    uint32_t a;
+    uint16_t b;
+    uint8_t c;
+
     ai = mrb_gc_arena_save(mrb);
 
+    i = pc - irep->iseq;
     next_file = mrb_debug_get_filename(irep, i);
     if (next_file && file != next_file) {
       printf("file: %s\n", next_file);
       file = next_file;
     }
-    line = mrb_debug_get_line(irep, i);
-    if (line < 0) {
-      printf("      ");
-    }
-    else {
-      printf("%5d ", line);
-    }
-
-    printf("%03d ", i);
-    c = irep->iseq[i];
-    switch (GET_OPCODE(c)) {
-    case OP_NOP:
+    print_header(irep, i);
+    ins = READ_B();
+    switch (ins) {
+    CASE(OP_NOP, Z):
       printf("OP_NOP\n");
       break;
-    case OP_MOVE:
-      printf("OP_MOVE\tR%d\tR%d\t", GETARG_A(c), GETARG_B(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_MOVE, BB):
+      printf("OP_MOVE\tR%d\tR%d\t", a, b);
+      print_lv_ab(mrb, irep, a, b);
       break;
-    case OP_LOADL:
+    CASE(OP_LOADL, BB):
       {
-        mrb_value v = irep->pool[GETARG_Bx(c)];
+        mrb_value v = irep->pool[b];
         mrb_value s = mrb_inspect(mrb, v);
-        printf("OP_LOADL\tR%d\tL(%d)\t; %s", GETARG_A(c), GETARG_Bx(c), RSTRING_PTR(s));
+        printf("OP_LOADL\tR%d\tL(%d)\t; %s", a, b, RSTRING_PTR(s));
       }
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_LOADI:
-      printf("OP_LOADI\tR%d\t%d\t", GETARG_A(c), GETARG_sBx(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_LOADSYM:
-      printf("OP_LOADSYM\tR%d\t:%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_LOADNIL:
-      printf("OP_LOADNIL\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_LOADSELF:
-      printf("OP_LOADSELF\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_LOADT:
-      printf("OP_LOADT\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_LOADF:
-      printf("OP_LOADF\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_GETGLOBAL:
-      printf("OP_GETGLOBAL\tR%d\t:%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_SETGLOBAL:
-      printf("OP_SETGLOBAL\t:%s\tR%d\t",
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]),
-             GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_GETCONST:
-      printf("OP_GETCONST\tR%d\t:%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_SETCONST:
-      printf("OP_SETCONST\t:%s\tR%d\t",
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]),
-             GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_GETMCNST:
-      printf("OP_GETMCNST\tR%d\tR%d::%s", GETARG_A(c), GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]));
-      print_lv(mrb, irep, c, RAB);
-      break;
-    case OP_SETMCNST:
-      printf("OP_SETMCNST\tR%d::%s\tR%d", GETARG_A(c)+1,
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]),
-             GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_GETIV:
-      printf("OP_GETIV\tR%d\t%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_SETIV:
-      printf("OP_SETIV\t%s\tR%d",
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]),
-             GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_GETUPVAR:
-      printf("OP_GETUPVAR\tR%d\t%d\t%d",
-             GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_SETUPVAR:
-      printf("OP_SETUPVAR\tR%d\t%d\t%d",
-             GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_GETCV:
-      printf("OP_GETCV\tR%d\t%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_SETCV:
-      printf("OP_SETCV\t%s\tR%d",
-             mrb_sym2name(mrb, irep->syms[GETARG_Bx(c)]),
-             GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
-      break;
-    case OP_JMP:
-      printf("OP_JMP\t%03d (%d)\n", i+GETARG_sBx(c), GETARG_sBx(c));
-      break;
-    case OP_JMPIF:
-      printf("OP_JMPIF\tR%d\t%03d (%d)\n", GETARG_A(c), i+GETARG_sBx(c), GETARG_sBx(c));
-      break;
-    case OP_JMPNOT:
-      printf("OP_JMPNOT\tR%d\t%03d (%d)\n", GETARG_A(c), i+GETARG_sBx(c), GETARG_sBx(c));
-      break;
-    case OP_SEND:
-      printf("OP_SEND\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_SENDB:
-      printf("OP_SENDB\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_CALL:
-      printf("OP_CALL\tR%d\n", GETARG_A(c));
-      break;
-    case OP_TAILCALL:
-      printf("OP_TAILCALL\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_SUPER:
-      printf("OP_SUPER\tR%d\t%d\n", GETARG_A(c),
-             GETARG_C(c));
-      break;
-    case OP_ARGARY:
-      printf("OP_ARGARY\tR%d\t%d:%d:%d:%d", GETARG_A(c),
-             (GETARG_Bx(c)>>10)&0x3f,
-             (GETARG_Bx(c)>>9)&0x1,
-             (GETARG_Bx(c)>>4)&0x1f,
-             (GETARG_Bx(c)>>0)&0xf);
-      print_lv(mrb, irep, c, RA);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADI, BB):
+      printf("OP_LOADI\tR%d\t%d\t", a, b);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADINEG, BB):
+      printf("OP_LOADI\tR%d\t-%d\t", a, b);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADI__1, B):
+      printf("OP_LOADI__1\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    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:
+      printf("OP_LOADI_%d\tR%d\t\t", ins-(int)OP_LOADI_0, a);
+      print_lv_a(mrb, irep, a);
       break;
-
-    case OP_ENTER:
+    CASE(OP_LOADSYM, BB):
+      printf("OP_LOADSYM\tR%d\t:%s\t", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADNIL, B):
+      printf("OP_LOADNIL\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADSELF, B):
+      printf("OP_LOADSELF\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADT, B):
+      printf("OP_LOADT\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LOADF, B):
+      printf("OP_LOADF\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETGV, BB):
+      printf("OP_GETGV\tR%d\t:%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETGV, BB):
+      printf("OP_SETGV\t:%s\tR%d", mrb_sym2name(mrb, irep->syms[b]), a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETSV, BB):
+      printf("OP_GETSV\tR%d\t:%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETSV, BB):
+      printf("OP_SETSV\t:%s\tR%d", mrb_sym2name(mrb, irep->syms[b]), a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETCONST, BB):
+      printf("OP_GETCONST\tR%d\t:%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETCONST, BB):
+      printf("OP_SETCONST\t:%s\tR%d", mrb_sym2name(mrb, irep->syms[b]), a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETMCNST, BB):
+      printf("OP_GETMCNST\tR%d\tR%d::%s", a, a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETMCNST, BB):
+      printf("OP_SETMCNST\tR%d::%s\tR%d", a+1, mrb_sym2name(mrb, irep->syms[b]), a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETIV, BB):
+      printf("OP_GETIV\tR%d\t%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETIV, BB):
+      printf("OP_SETIV\t%s\tR%d", mrb_sym2name(mrb, irep->syms[b]), a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETUPVAR, BBB):
+      printf("OP_GETUPVAR\tR%d\t%d\t%d", a, b, c);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETUPVAR, BBB):
+      printf("OP_SETUPVAR\tR%d\t%d\t%d", a, b, c);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_GETCV, BB):
+      printf("OP_GETCV\tR%d\t%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SETCV, BB):
+      printf("OP_SETCV\t%s\tR%d", mrb_sym2name(mrb, irep->syms[b]), a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_JMP, S):
+      printf("OP_JMP\t\t%03d\n", a);
+      break;
+    CASE(OP_JMPIF, BS):
+      printf("OP_JMPIF\tR%d\t%03d\t", a, b);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_JMPNOT, BS):
+      printf("OP_JMPNOT\tR%d\t%03d\t", a, b);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_JMPNIL, BS):
+      printf("OP_JMPNIL\tR%d\t%03d\t", a, b);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_SENDV, BB):
+      printf("OP_SENDV\tR%d\t:%s\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_SENDVB, BB):
+      printf("OP_SENDVB\tR%d\t:%s\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_SEND, BBB):
+      printf("OP_SEND\tR%d\t:%s\t%d\n", a, mrb_sym2name(mrb, irep->syms[b]), c);
+      break;
+    CASE(OP_SENDB, BBB):
+      printf("OP_SENDB\tR%d\t:%s\t%d\n", a, mrb_sym2name(mrb, irep->syms[b]), c);
+      break;
+    CASE(OP_CALL, Z):
+      printf("OP_CALL\n");
+      break;
+    CASE(OP_SUPER, BB):
+      printf("OP_SUPER\tR%d\t%d\n", a, b);
+      break;
+    CASE(OP_ARGARY, BS):
+      printf("OP_ARGARY\tR%d\t%d:%d:%d:%d", a,
+             (b>>10)&0x3f,
+             (b>>9)&0x1,
+             (b>>4)&0x1f,
+             (b>>0)&0xf);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_ENTER, W):
       printf("OP_ENTER\t%d:%d:%d:%d:%d:%d:%d\n",
-             (GETARG_Ax(c)>>18)&0x1f,
-             (GETARG_Ax(c)>>13)&0x1f,
-             (GETARG_Ax(c)>>12)&0x1,
-             (GETARG_Ax(c)>>7)&0x1f,
-             (GETARG_Ax(c)>>2)&0x1f,
-             (GETARG_Ax(c)>>1)&0x1,
-             GETARG_Ax(c) & 0x1);
-      break;
-    case OP_RETURN:
-      printf("OP_RETURN\tR%d", GETARG_A(c));
-      switch (GETARG_B(c)) {
-      case OP_R_NORMAL:
-        printf("\tnormal\t"); break;
-      case OP_R_RETURN:
-        printf("\treturn\t"); break;
-      case OP_R_BREAK:
-        printf("\tbreak\t"); break;
-      default:
-        printf("\tbroken\t"); break;
-      }
-      print_lv(mrb, irep, c, RA);
+             (a>>18)&0x1f,
+             (a>>13)&0x1f,
+             (a>>12)&0x1,
+             (a>>7)&0x1f,
+             (a>>2)&0x1f,
+             (a>>1)&0x1,
+             a & 0x1);
       break;
-    case OP_BLKPUSH:
-      printf("OP_BLKPUSH\tR%d\t%d:%d:%d:%d", GETARG_A(c),
-             (GETARG_Bx(c)>>10)&0x3f,
-             (GETARG_Bx(c)>>9)&0x1,
-             (GETARG_Bx(c)>>4)&0x1f,
-             (GETARG_Bx(c)>>0)&0xf);
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_KARG, BB):
+      printf("OP_KARG\tR(%d)\tK(%d)\n", a, b);
       break;
-
-    case OP_LAMBDA:
-      printf("OP_LAMBDA\tR%d\tI(%+d)\t", GETARG_A(c), GETARG_b(c)+1);
-      switch (GETARG_c(c)) {
-      case OP_L_METHOD:
-        printf("method"); break;
-      case OP_L_BLOCK:
-        printf("block"); break;
-      case OP_L_LAMBDA:
-        printf("lambda"); break;
-      }
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_KARG2, BB):
+      printf("OP_KARG2\tR(%d)\tK(%d)\n", a, b);
       break;
-    case OP_RANGE:
-      printf("OP_RANGE\tR%d\tR%d\t%d", GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_KDICT, B):
+      printf("OP_KDICt\tR(%d)\n", a);
       break;
-    case OP_METHOD:
-      printf("OP_METHOD\tR%d\t:%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_RETURN, B):
+      printf("OP_RETURN\tR%d", a);
+      print_lv_a(mrb, irep, a);
       break;
-
-    case OP_ADD:
-      printf("OP_ADD\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_ADDI:
-      printf("OP_ADDI\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_SUB:
-      printf("OP_SUB\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_SUBI:
-      printf("OP_SUBI\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_MUL:
-      printf("OP_MUL\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_DIV:
-      printf("OP_DIV\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_LT:
-      printf("OP_LT\t\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_LE:
-      printf("OP_LE\t\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_GT:
-      printf("OP_GT\t\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_GE:
-      printf("OP_GE\t\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
-      break;
-    case OP_EQ:
-      printf("OP_EQ\t\tR%d\t:%s\t%d\n", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]),
-             GETARG_C(c));
+    CASE(OP_RETURN_BLK, B):
+      printf("OP_RETURN_BLK\tR%d", a);
+      print_lv_a(mrb, irep, a);
       break;
-
-    case OP_STOP:
-      printf("OP_STOP\n");
+    CASE(OP_BREAK, B):
+      printf("OP_BREAK\tR%d", a);
+      print_lv_a(mrb, irep, a);
       break;
-
-    case OP_ARRAY:
-      printf("OP_ARRAY\tR%d\tR%d\t%d", GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_BLKPUSH, BS):
+      printf("OP_BLKPUSH\tR%d\t%d:%d:%d:%d", a,
+             (b>>10)&0x3f,
+             (b>>9)&0x1,
+             (b>>4)&0x1f,
+             (b>>0)&0xf);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_LAMBDA, BB):
+      printf("OP_LAMBDA\tR%d\tI(%d:%p)\n", a, b, irep->reps[b]);
+      break;
+    CASE(OP_BLOCK, BB):
+      printf("OP_BLOCK\tR%d\tI(%d:%p)\n", a, b, irep->reps[b]);
+      break;
+    CASE(OP_METHOD, BB):
+      printf("OP_METHOD\tR%d\tI(%d:%p)\n", a, b, irep->reps[b]);
+      break;
+    CASE(OP_RANGE_INC, B):
+      printf("OP_RANGE_INC\tR%d\n", a);
+      break;
+    CASE(OP_RANGE_EXC, B):
+      printf("OP_RANGE_EXC\tR%d\n", a);
+      break;
+    CASE(OP_DEF, BB):
+      printf("OP_DEF\tR%d\t:%s\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_UNDEF, B):
+      printf("OP_UNDEF\t:%s\n", mrb_sym2name(mrb, irep->syms[a]));
+      break;
+    CASE(OP_ALIAS, BB):
+      printf("OP_ALIAS\t:%s\t%s\n", mrb_sym2name(mrb, irep->syms[a]), mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_ADD, BB):
+      printf("OP_ADD\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_ADDI, BBB):
+      printf("OP_ADDI\tR%d\t:%s\t%d\n", a, mrb_sym2name(mrb, irep->syms[b]), c);
+      break;
+    CASE(OP_SUB, BB):
+      printf("OP_SUB\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_SUBI, BBB):
+      printf("OP_SUBI\tR%d\t:%s\t%d\n", a, mrb_sym2name(mrb, irep->syms[b]), c);
+      break;
+    CASE(OP_MUL, BB):
+      printf("OP_MUL\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_DIV, BB):
+      printf("OP_DIV\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_LT, BB):
+      printf("OP_LT\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_LE, BB):
+      printf("OP_LE\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_GT, BB):
+      printf("OP_GT\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_GE, BB):
+      printf("OP_GE\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+      break;
+    CASE(OP_EQ, BB):
+      printf("OP_EQ\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
       break;
-    case OP_ARYCAT:
-      printf("OP_ARYCAT\tR%d\tR%d\t", GETARG_A(c), GETARG_B(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_ARRAY, BB):
+      printf("OP_ARRAY\tR%d\t%d\t", a, b);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_ARYPUSH:
-      printf("OP_ARYPUSH\tR%d\tR%d\t", GETARG_A(c), GETARG_B(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_ARRAY2, BBB):
+      printf("OP_ARRAY\tR%d\tR%d\t%d\t", a, b, c);
+      print_lv_ab(mrb, irep, a, b);
       break;
-    case OP_AREF:
-      printf("OP_AREF\tR%d\tR%d\t%d", GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_ARYCAT, B):
+      printf("OP_ARYCAT\tR%d\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_APOST:
-      printf("OP_APOST\tR%d\t%d\t%d", GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_ARYPUSH, B):
+      printf("OP_ARYPUSH\tR%d\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_STRING:
+    CASE(OP_ARYDUP, B):
+      printf("OP_ARYDUP\tR%d\t", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_AREF, BBB):
+      printf("OP_AREF\tR%d\tR%d\t%d", a, b, c);
+      print_lv_ab(mrb, irep, a, b);
+      break;
+    CASE(OP_ASET, BBB):
+      printf("OP_ASET\tR%d\tR%d\t%d", a, b, c);
+      print_lv_ab(mrb, irep, a, b);
+      break;
+    CASE(OP_APOST, BBB):
+      printf("OP_APOST\tR%d\t%d\t%d", a, b, c);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_INTERN, B):
+      printf("OP_INTERN\tR%d", a);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_STRING, BB):
       {
-        mrb_value v = irep->pool[GETARG_Bx(c)];
+        mrb_value v = irep->pool[b];
         mrb_value s = mrb_str_dump(mrb, mrb_str_new(mrb, RSTRING_PTR(v), RSTRING_LEN(v)));
-        printf("OP_STRING\tR%d\tL(%d)\t; %s", GETARG_A(c), GETARG_Bx(c), RSTRING_PTR(s));
+        printf("OP_STRING\tR%d\tL(%d)\t; %s", a, b, RSTRING_PTR(s));
       }
-      print_lv(mrb, irep, c, RA);
+      print_lv_a(mrb, irep, a);
+      break;
+    CASE(OP_STRCAT, B):
+      printf("OP_STRCAT\tR%d\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_STRCAT:
-      printf("OP_STRCAT\tR%d\tR%d\t", GETARG_A(c), GETARG_B(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_HASH, BB):
+      printf("OP_HASH\tR%d\t%d\t", a, b);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_HASH:
-      printf("OP_HASH\tR%d\tR%d\t%d", GETARG_A(c), GETARG_B(c), GETARG_C(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_HASHADD, BB):
+      printf("OP_HASHADD\tR%d\t%d", a, b);
+      print_lv_a(mrb, irep, a);
       break;
 
-    case OP_OCLASS:
-      printf("OP_OCLASS\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_OCLASS, B):
+      printf("OP_OCLASS\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_CLASS:
-      printf("OP_CLASS\tR%d\t:%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_CLASS, BB):
+      printf("OP_CLASS\tR%d\t:%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_MODULE:
-      printf("OP_MODULE\tR%d\t:%s", GETARG_A(c),
-             mrb_sym2name(mrb, irep->syms[GETARG_B(c)]));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_MODULE, BB):
+      printf("OP_MODULE\tR%d\t:%s", a, mrb_sym2name(mrb, irep->syms[b]));
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_EXEC:
-      printf("OP_EXEC\tR%d\tI(%+d)", GETARG_A(c), GETARG_Bx(c)+1);
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_EXEC, BB):
+      printf("OP_EXEC\tR%d\tI(%d:%p)", a, b, irep->reps[b]);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_SCLASS:
-      printf("OP_SCLASS\tR%d\tR%d\t", GETARG_A(c), GETARG_B(c));
-      print_lv(mrb, irep, c, RAB);
+    CASE(OP_SCLASS, B):
+      printf("OP_SCLASS\tR%d\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_TCLASS:
-      printf("OP_TCLASS\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_TCLASS, B):
+      printf("OP_TCLASS\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_ERR:
+    CASE(OP_ERR, B):
       {
-        mrb_value v = irep->pool[GETARG_Bx(c)];
+        mrb_value v = irep->pool[a];
         mrb_value s = mrb_str_dump(mrb, mrb_str_new(mrb, RSTRING_PTR(v), RSTRING_LEN(v)));
         printf("OP_ERR\t%s\n", RSTRING_PTR(s));
       }
       break;
-    case OP_EPUSH:
-      printf("OP_EPUSH\t:I(%+d)\n", GETARG_Bx(c)+1);
+    CASE(OP_EPUSH, B):
+      printf("OP_EPUSH\t\t:I(%d:%p)\n", a, irep->reps[a]);
       break;
-    case OP_ONERR:
-      printf("OP_ONERR\t%03d\n", i+GETARG_sBx(c));
+    CASE(OP_ONERR, S):
+      printf("OP_ONERR\t%03d\n", a);
       break;
-    case OP_RESCUE:
-      {
-        int a = GETARG_A(c);
-        int b = GETARG_B(c);
-        int cnt = GETARG_C(c);
-
-        if (b == 0) {
-          printf("OP_RESCUE\tR%d\t\t%s", a, cnt ? "cont" : "");
-          print_lv(mrb, irep, c, RA);
-          break;
-        }
-        else {
-          printf("OP_RESCUE\tR%d\tR%d\t%s", a, b, cnt ? "cont" : "");
-          print_lv(mrb, irep, c, RAB);
-          break;
-        }
-      }
+    CASE(OP_EXCEPT, B):
+      printf("OP_EXCEPT\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_RAISE:
-      printf("OP_RAISE\tR%d\t\t", GETARG_A(c));
-      print_lv(mrb, irep, c, RA);
+    CASE(OP_RESCUE, BB):
+      printf("OP_RESCUE\tR%d\tR%d", a, b);
+      print_lv_ab(mrb, irep, a, b);
       break;
-    case OP_POPERR:
-      printf("OP_POPERR\t%d\t\t\n", GETARG_A(c));
+    CASE(OP_RAISE, B):
+      printf("OP_RAISE\tR%d\t\t", a);
+      print_lv_a(mrb, irep, a);
       break;
-    case OP_EPOP:
-      printf("OP_EPOP\t%d\n", GETARG_A(c));
+    CASE(OP_POPERR, B):
+      printf("OP_POPERR\t%d\t\t\n", a);
+      break;
+    CASE(OP_EPOP, B):
+      printf("OP_EPOP\t%d\n", a);
       break;
 
+    CASE(OP_DEBUG, BBB):
+      printf("OP_DEBUG\t%d\t%d\t%d\n", a, b, c);
+      break;
+
+    CASE(OP_STOP, Z):
+      printf("OP_STOP\n");
+      break;
+
+    CASE(OP_EXT1, Z):
+      ins = READ_B();
+      printf("OP_EXT1\n");
+      print_header(irep, pc-irep->iseq-2);
+      switch (ins) {
+#define OPCODE(i,x) case OP_ ## i: FETCH_ ## x ## _1 (); goto L_OP_ ## i;
+#include "mruby/ops.h"
+#undef OPCODE
+      }
+      break;
+    CASE(OP_EXT2, Z):
+      ins = READ_B();
+      printf("OP_EXT2\n");
+      print_header(irep, pc-irep->iseq-2);
+      switch (ins) {
+#define OPCODE(i,x) case OP_ ## i: FETCH_ ## x ## _2 (); goto L_OP_ ## i;
+#include "mruby/ops.h"
+#undef OPCODE
+      }
+      break;
+    CASE(OP_EXT3, Z):
+      ins = READ_B();
+      printf("OP_EXT3\n");
+      print_header(irep, pc-irep->iseq-2);
+      switch (ins) {
+#define OPCODE(i,x) case OP_ ## i: FETCH_ ## x ## _3 (); goto L_OP_ ## i;
+#include "mruby/ops.h"
+#undef OPCODE
+      }
+      break;
+      
     default:
-      printf("OP_unknown %d\t%d\t%d\t%d\n", GET_OPCODE(c),
-             GETARG_A(c), GETARG_B(c), GETARG_C(c));
+      printf("OP_unknown (0x%x)\n", ins);
       break;
     }
     mrb_gc_arena_restore(mrb, ai);
diff --git a/src/kernel.c b/src/kernel.c
index bbe6e8bb7..155868eaa 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -1266,5 +1266,5 @@ mrb_init_kernel(mrb_state *mrb)
   mrb_define_method(mrb, krn, "class_defined?",             mrb_krn_class_defined,           MRB_ARGS_REQ(1));
 
   mrb_include_module(mrb, mrb->object_class, mrb->kernel_module);
-  mrb_alias_method(mrb, mrb->module_class, mrb_intern_lit(mrb, "dup"), mrb_intern_lit(mrb, "clone"));
+  mrb_define_alias(mrb, mrb->module_class, "dup", "clone"); /* XXX */
 }
diff --git a/src/load.c b/src/load.c
index ddf3cdfbf..20878aa56 100644
--- a/src/load.c
+++ b/src/load.c
@@ -79,7 +79,7 @@ read_irep_record_1(mrb_state *mrb, const uint8_t *bin, size_t *len, uint8_t flag
     if ((flags & FLAG_SRC_MALLOC) == 0 &&
         (flags & FLAG_BYTEORDER_NATIVE)) {
       irep->iseq = (mrb_code*)src;
-      src += sizeof(uint32_t) * irep->ilen;
+      src += sizeof(mrb_code) * irep->ilen;
       irep->flags |= MRB_ISEQ_NO_FREE;
     }
     else {
diff --git a/src/proc.c b/src/proc.c
index c6e9be433..05b897480 100644
--- a/src/proc.c
+++ b/src/proc.c
@@ -10,7 +10,7 @@
 #include <mruby/opcode.h>
 
 static mrb_code call_iseq[] = {
-  MKOP_A(OP_CALL, 0),
+  OP_CALL,
 };
 
 struct RProc*
@@ -223,7 +223,7 @@ mrb_proc_arity(mrb_state *mrb, mrb_value self)
 {
   struct RProc *p = mrb_proc_ptr(self);
   struct mrb_irep *irep;
-  mrb_code *iseq;
+  mrb_code *pc;
   mrb_aspec aspec;
   int ma, op, ra, pa, arity;
 
@@ -237,13 +237,13 @@ mrb_proc_arity(mrb_state *mrb, mrb_value self)
     return mrb_fixnum_value(0);
   }
 
-  iseq = irep->iseq;
+  pc = irep->iseq;
   /* arity is depend on OP_ENTER */
-  if (GET_OPCODE(*iseq) != OP_ENTER) {
+  if (*pc != OP_ENTER) {
     return mrb_fixnum_value(0);
   }
 
-  aspec = GETARG_Ax(*iseq);
+  aspec = PEEK_W(pc+1);
   ma = MRB_ASPEC_REQ(aspec);
   op = MRB_ASPEC_OPT(aspec);
   ra = MRB_ASPEC_REST(aspec);
diff --git a/src/vm.c b/src/vm.c
index 7a436828a..b50f1ee9f 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -333,7 +333,7 @@ ecall(mrb_state *mrb)
   struct REnv *env;
   ptrdiff_t cioff;
   int ai = mrb_gc_arena_save(mrb);
-  int i = --c->eidx;
+  uint8_t i = --c->eidx;
   int nregs;
 
   if (i<0) return;
@@ -911,18 +911,18 @@ argnum_error(mrb_state *mrb, mrb_int num)
 
 #ifndef DIRECT_THREADED
 
-#define INIT_DISPATCH for (;;) { i = BYTECODE_DECODER(*pc); CODE_FETCH_HOOK(mrb, irep, pc, regs); switch (GET_OPCODE(i)) {
-#define CASE(op) case op:
-#define NEXT pc++; break
-#define JUMP break
+#define INIT_DISPATCH for (;;) { insn = BYTECODE_DECODER(*pc); pc++; CODE_FETCH_HOOK(mrb, irep, pc, regs); switch (insn) {
+#define CASE(insn,ops) case insn: pc++; FETCH_ ## ops ();; L_ ## insn ## _BODY:
+#define NEXT break
+#define JUMP NEXT
 #define END_DISPATCH }}
 
 #else
 
 #define INIT_DISPATCH JUMP; return mrb_nil_value();
-#define CASE(op) L_ ## op:
-#define NEXT i=BYTECODE_DECODER(*++pc); CODE_FETCH_HOOK(mrb, irep, pc, regs); goto *optable[GET_OPCODE(i)]
-#define JUMP i=BYTECODE_DECODER(*pc); CODE_FETCH_HOOK(mrb, irep, pc, regs); goto *optable[GET_OPCODE(i)]
+#define CASE(insn,ops) L_ ## insn: pc++; FETCH_ ## ops (); 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
 
@@ -958,6 +958,17 @@ mrb_vm_run(mrb_state *mrb, struct RProc *proc, mrb_value self, unsigned int stac
   return result;
 }
 
+static mrb_bool
+check_target_class(mrb_state *mrb)
+{
+  if (!mrb->c->ci->target_class) {
+    mrb_value exc = mrb_exc_new_str_lit(mrb, E_TYPE_ERROR, "no target class or module");
+    mrb_exc_set(mrb, exc);
+    return FALSE;
+  }
+  return TRUE;
+}
+
 MRB_API mrb_value
 mrb_vm_exec(mrb_state *mrb, struct RProc *proc, mrb_code *pc)
 {
@@ -965,33 +976,19 @@ mrb_vm_exec(mrb_state *mrb, struct RProc *proc, mrb_code *pc)
   mrb_irep *irep = proc->body.irep;
   mrb_value *pool = irep->pool;
   mrb_sym *syms = irep->syms;
-  mrb_code i;
+  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;
+  uint8_t c;
 
 #ifdef DIRECT_THREADED
   static void *optable[] = {
-    &&L_OP_NOP, &&L_OP_MOVE,
-    &&L_OP_LOADL, &&L_OP_LOADI, &&L_OP_LOADSYM, &&L_OP_LOADNIL,
-    &&L_OP_LOADSELF, &&L_OP_LOADT, &&L_OP_LOADF,
-    &&L_OP_GETGLOBAL, &&L_OP_SETGLOBAL, &&L_OP_GETSPECIAL, &&L_OP_SETSPECIAL,
-    &&L_OP_GETIV, &&L_OP_SETIV, &&L_OP_GETCV, &&L_OP_SETCV,
-    &&L_OP_GETCONST, &&L_OP_SETCONST, &&L_OP_GETMCNST, &&L_OP_SETMCNST,
-    &&L_OP_GETUPVAR, &&L_OP_SETUPVAR,
-    &&L_OP_JMP, &&L_OP_JMPIF, &&L_OP_JMPNOT,
-    &&L_OP_ONERR, &&L_OP_RESCUE, &&L_OP_POPERR, &&L_OP_RAISE, &&L_OP_EPUSH, &&L_OP_EPOP,
-    &&L_OP_SEND, &&L_OP_SENDB, &&L_OP_FSEND,
-    &&L_OP_CALL, &&L_OP_SUPER, &&L_OP_ARGARY, &&L_OP_ENTER,
-    &&L_OP_KARG, &&L_OP_KDICT, &&L_OP_RETURN, &&L_OP_TAILCALL, &&L_OP_BLKPUSH,
-    &&L_OP_ADD, &&L_OP_ADDI, &&L_OP_SUB, &&L_OP_SUBI, &&L_OP_MUL, &&L_OP_DIV,
-    &&L_OP_EQ, &&L_OP_LT, &&L_OP_LE, &&L_OP_GT, &&L_OP_GE,
-    &&L_OP_ARRAY, &&L_OP_ARYCAT, &&L_OP_ARYPUSH, &&L_OP_AREF, &&L_OP_ASET, &&L_OP_APOST,
-    &&L_OP_STRING, &&L_OP_STRCAT, &&L_OP_HASH,
-    &&L_OP_LAMBDA, &&L_OP_RANGE, &&L_OP_OCLASS,
-    &&L_OP_CLASS, &&L_OP_MODULE, &&L_OP_EXEC,
-    &&L_OP_METHOD, &&L_OP_SCLASS, &&L_OP_TCLASS,
-    &&L_OP_DEBUG, &&L_OP_STOP, &&L_OP_ERR,
+#define OPCODE(x,_) &&L_OP_ ## x,
+#include "mruby/ops.h"
+#undef OPCODE
   };
 #endif
 
@@ -1013,25 +1010,19 @@ RETRY_TRY_BLOCK:
 
 #define regs (mrb->c->stack)
   INIT_DISPATCH {
-    CASE(OP_NOP) {
+    CASE(OP_NOP, Z) {
       /* do nothing */
       NEXT;
     }
 
-    CASE(OP_MOVE) {
-      /* A B    R(A) := R(B) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
+    CASE(OP_MOVE, BB) {
       regs[a] = regs[b];
       NEXT;
     }
 
-    CASE(OP_LOADL) {
-      /* A Bx   R(A) := Pool(Bx) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
+    CASE(OP_LOADL, BB) {
 #ifdef MRB_WORD_BOXING
-      mrb_value val = pool[bx];
+      mrb_value val = pool[b];
 #ifndef MRB_WITHOUT_FLOAT
       if (mrb_float_p(val)) {
         val = mrb_float_value(mrb, mrb_float(val));
@@ -1039,125 +1030,110 @@ RETRY_TRY_BLOCK:
 #endif
       regs[a] = val;
 #else
-      regs[a] = pool[bx];
+      regs[a] = pool[b];
 #endif
       NEXT;
     }
 
-    CASE(OP_LOADI) {
-      /* A sBx  R(A) := sBx */
-      int a = GETARG_A(i);
-      mrb_int bx = GETARG_sBx(i);
-      SET_INT_VALUE(regs[a], bx);
+    CASE(OP_LOADI, BB) {
+      SET_INT_VALUE(regs[a], b);
+      NEXT;
+    }
+
+    CASE(OP_LOADINEG, BB) {
+      SET_INT_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_INT_VALUE(regs[a], (mrb_int)insn - (mrb_int)OP_LOADI_0);
+      NEXT;
+    }
+
+    CASE(OP_LOADSYM, BB) {
+      SET_SYM_VALUE(regs[a], syms[b]);
       NEXT;
     }
 
-    CASE(OP_LOADSYM) {
-      /* A Bx   R(A) := Syms(Bx) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      SET_SYM_VALUE(regs[a], syms[bx]);
+    CASE(OP_LOADNIL, B) {
+      SET_NIL_VALUE(regs[a]);
       NEXT;
     }
 
-    CASE(OP_LOADSELF) {
-      /* A      R(A) := self */
-      int a = GETARG_A(i);
+    CASE(OP_LOADSELF, B) {
       regs[a] = regs[0];
       NEXT;
     }
 
-    CASE(OP_LOADT) {
-      /* A      R(A) := true */
-      int a = GETARG_A(i);
+    CASE(OP_LOADT, B) {
       SET_TRUE_VALUE(regs[a]);
       NEXT;
     }
 
-    CASE(OP_LOADF) {
-      /* A      R(A) := false */
-      int a = GETARG_A(i);
+    CASE(OP_LOADF, B) {
       SET_FALSE_VALUE(regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETGLOBAL) {
-      /* A Bx   R(A) := getglobal(Syms(Bx)) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_value val = mrb_gv_get(mrb, syms[bx]);
+    CASE(OP_GETGV, BB) {
+      mrb_value val = mrb_gv_get(mrb, syms[b]);
       regs[a] = val;
       NEXT;
     }
 
-    CASE(OP_SETGLOBAL) {
-      /* A Bx   setglobal(Syms(Bx), R(A)) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_gv_set(mrb, syms[bx], regs[a]);
+    CASE(OP_SETGV, BB) {
+      mrb_gv_set(mrb, syms[b], regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETSPECIAL) {
-      /* A Bx   R(A) := Special[Bx] */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_value val = mrb_vm_special_get(mrb, bx);
+    CASE(OP_GETSV, BB) {
+      mrb_value val = mrb_vm_special_get(mrb, b);
       regs[a] = val;
       NEXT;
     }
 
-    CASE(OP_SETSPECIAL) {
-      /* A Bx   Special[Bx] := R(A) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_vm_special_set(mrb, bx, regs[a]);
+    CASE(OP_SETSV, BB) {
+      mrb_vm_special_set(mrb, b, regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETIV) {
-      /* A Bx   R(A) := ivget(Bx) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_value val = mrb_vm_iv_get(mrb, syms[bx]);
+    CASE(OP_GETIV, BB) {
+      mrb_value val = mrb_vm_iv_get(mrb, syms[b]);
       regs[a] = val;
       NEXT;
     }
 
-    CASE(OP_SETIV) {
-      /* A Bx   ivset(Syms(Bx),R(A)) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_vm_iv_set(mrb, syms[bx], regs[a]);
+    CASE(OP_SETIV, BB) {
+      mrb_vm_iv_set(mrb, syms[b], regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETCV) {
-      /* A Bx   R(A) := cvget(Syms(Bx)) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
+    CASE(OP_GETCV, BB) {
       mrb_value val;
       ERR_PC_SET(mrb, pc);
-      val = mrb_vm_cv_get(mrb, syms[bx]);
+      val = mrb_vm_cv_get(mrb, syms[b]);
       ERR_PC_CLR(mrb);
       regs[a] = val;
       NEXT;
     }
 
-    CASE(OP_SETCV) {
-      /* A Bx   cvset(Syms(Bx),R(A)) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_vm_cv_set(mrb, syms[bx], regs[a]);
+    CASE(OP_SETCV, BB) {
+      mrb_vm_cv_set(mrb, syms[b], regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETCONST) {
-      /* A Bx    R(A) := constget(Syms(Bx)) */
+    CASE(OP_GETCONST, BB) {
       mrb_value val;
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_sym sym = syms[bx];
+      mrb_sym sym = syms[b];
 
       ERR_PC_SET(mrb, pc);
       val = mrb_vm_const_get(mrb, sym);
@@ -1166,40 +1142,27 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_SETCONST) {
-      /* A Bx   constset(Syms(Bx),R(A)) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_vm_const_set(mrb, syms[bx], regs[a]);
+    CASE(OP_SETCONST, BB) {
+      mrb_vm_const_set(mrb, syms[b], regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETMCNST) {
-      /* A Bx   R(A) := R(A)::Syms(Bx) */
+    CASE(OP_GETMCNST, BB) {
       mrb_value val;
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
 
       ERR_PC_SET(mrb, pc);
-      val = mrb_const_get(mrb, regs[a], syms[bx]);
+      val = mrb_const_get(mrb, regs[a], syms[b]);
       ERR_PC_CLR(mrb);
       regs[a] = val;
       NEXT;
     }
 
-    CASE(OP_SETMCNST) {
-      /* A Bx    R(A+1)::Syms(Bx) := R(A) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      mrb_const_set(mrb, regs[a+1], syms[bx], regs[a]);
+    CASE(OP_SETMCNST, BB) {
+      mrb_const_set(mrb, regs[a+1], syms[b], regs[a]);
       NEXT;
     }
 
-    CASE(OP_GETUPVAR) {
-      /* A B C  R(A) := uvget(B,C) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
+    CASE(OP_GETUPVAR, BBB) {
       mrb_value *regs_a = regs + a;
       struct REnv *e = uvenv(mrb, c);
 
@@ -1212,12 +1175,7 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_SETUPVAR) {
-      /* A B C  uvset(B,C,R(A)) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
-
+    CASE(OP_SETUPVAR, BBB) {
       struct REnv *e = uvenv(mrb, c);
 
       if (e) {
@@ -1231,110 +1189,86 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_JMP) {
-      /* sBx    pc+=sBx */
-      int sbx = GETARG_sBx(i);
-      pc += sbx;
+    CASE(OP_JMP, S) {
+      pc = irep->iseq+a;
       JUMP;
     }
-
-    CASE(OP_JMPIF) {
-      /* A sBx  if R(A) pc+=sBx */
-      int a = GETARG_A(i);
-      int sbx = GETARG_sBx(i);
+    CASE(OP_JMPIF, BS) {
       if (mrb_test(regs[a])) {
-        pc += sbx;
+        pc = irep->iseq+b;
         JUMP;
       }
       NEXT;
     }
-
-    CASE(OP_JMPNOT) {
-      /* A sBx  if !R(A) pc+=sBx */
-      int a = GETARG_A(i);
-      int sbx = GETARG_sBx(i);
+    CASE(OP_JMPNOT, BS) {
       if (!mrb_test(regs[a])) {
-        pc += sbx;
+        pc = irep->iseq+b;
+        JUMP;
+      }
+      NEXT;
+    }
+    CASE(OP_JMPNIL, BS) {
+      if (mrb_nil_p(regs[a])) {
+        pc = irep->iseq+b;
         JUMP;
       }
       NEXT;
     }
 
-    CASE(OP_ONERR) {
-      /* sBx    pc+=sBx on exception */
-      int sbx = GETARG_sBx(i);
+    CASE(OP_ONERR, S) {
       if (mrb->c->rsize <= mrb->c->ci->ridx) {
         if (mrb->c->rsize == 0) mrb->c->rsize = RESCUE_STACK_INIT_SIZE;
         else mrb->c->rsize *= 2;
-        mrb->c->rescue = (mrb_code **)mrb_realloc(mrb, mrb->c->rescue, sizeof(mrb_code*) * mrb->c->rsize);
+        mrb->c->rescue = (uint16_t*)mrb_realloc(mrb, mrb->c->rescue, sizeof(uint16_t) * mrb->c->rsize);
       }
-      mrb->c->rescue[mrb->c->ci->ridx++] = pc + sbx;
+      mrb->c->rescue[mrb->c->ci->ridx++] = a;
       NEXT;
     }
 
-    CASE(OP_RESCUE) {
-      /* A B    R(A) := exc; clear(exc); R(B) := matched (bool) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
-      mrb_value exc;
-
-      if (c == 0) {
-        exc = mrb_obj_value(mrb->exc);
-        mrb->exc = 0;
-      }
-      else {           /* continued; exc taken from R(A) */
-        exc = regs[a];
-      }
-      if (b != 0) {
-        mrb_value e = regs[b];
-        struct RClass *ec;
+    CASE(OP_EXCEPT, B) {
+      mrb_value exc = mrb_obj_value(mrb->exc);
+      mrb->exc = 0;
+      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;
+      switch (mrb_type(e)) {
+      case MRB_TT_CLASS:
+      case MRB_TT_MODULE:
+        break;
+      default:
+        {
+          mrb_value exc;
 
-            exc = mrb_exc_new_str_lit(mrb, E_TYPE_ERROR,
-                  "class or module required for rescue clause");
-            mrb_exc_set(mrb, exc);
-            goto L_RAISE;
-          }
+          exc = mrb_exc_new_str_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));
-      }
-      if (a != 0 && c == 0) {
-        regs[a] = exc;
       }
+      ec = mrb_class_ptr(e);
+      regs[b] = mrb_bool_value(mrb_obj_is_kind_of(mrb, exc, ec));
       NEXT;
     }
 
-    CASE(OP_POPERR) {
-      /* A      A.times{rescue_pop()} */
-      int a = GETARG_A(i);
-
+    CASE(OP_POPERR, B) {
       mrb->c->ci->ridx -= a;
       NEXT;
     }
 
-    CASE(OP_RAISE) {
-      /* A      raise(R(A)) */
-      int a = GETARG_A(i);
-
+    CASE(OP_RAISE, B) {
       mrb_exc_set(mrb, regs[a]);
       goto L_RAISE;
     }
 
-    CASE(OP_EPUSH) {
-      /* Bx     ensure_push(SEQ[Bx]) */
-      int bx = GETARG_Bx(i);
+    CASE(OP_EPUSH, B) {
       struct RProc *p;
 
-      p = mrb_closure_new(mrb, irep->reps[bx]);
+      p = mrb_closure_new(mrb, irep->reps[a]);
       /* push ensure_stack */
       if (mrb->c->esize <= mrb->c->eidx+1) {
         if (mrb->c->esize == 0) mrb->c->esize = ENSURE_STACK_INIT_SIZE;
@@ -1347,11 +1281,9 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_EPOP) {
-      /* A      A.times{ensure_pop().call} */
-      int a = GETARG_A(i);
+    CASE(OP_EPOP, B) {
       mrb_callinfo *ci = mrb->c->ci;
-      int n, epos = ci->epos;
+      unsigned int n, epos = ci->epos;
       mrb_value self = regs[0];
       struct RClass *target_class = ci->target_class;
 
@@ -1359,9 +1291,8 @@ RETRY_TRY_BLOCK:
         NEXT;
       }
 
-      if (a > mrb->c->eidx - epos)
+      if (a > (int)mrb->c->eidx - epos)
         a = mrb->c->eidx - epos;
-      pc = pc + 1;
       for (n=0; n<a; n++) {
         proc = mrb->c->ensure[epos+n];
         mrb->c->ensure[epos+n] = NULL;
@@ -1387,29 +1318,32 @@ RETRY_TRY_BLOCK:
       JUMP;
     }
 
-    CASE(OP_LOADNIL) {
-      /* A     R(A) := nil */
-      int a = GETARG_A(i);
+    CASE(OP_SENDV, BB) {
+      c = CALL_MAXARGS;
+      goto L_SEND;
+    };
 
-      SET_NIL_VALUE(regs[a]);
-      NEXT;
-    }
+    CASE(OP_SENDVB, BB) {
+      c = CALL_MAXARGS;
+      goto L_SENDB;
+    };
 
-    CASE(OP_SENDB) {
-      /* A B C  R(A) := call(R(A),Syms(B),R(A+1),...,R(A+C),&R(A+C+1))*/
-      /* fall through */
+    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:
-    CASE(OP_SEND) {
-      /* A B C  R(A) := call(R(A),Syms(B),R(A+1),...,R(A+C)) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int n = GETARG_C(i);
-      int argc = (n == CALL_MAXARGS) ? -1 : n;
-      int bidx = (argc < 0) ? a+2 : a+n+1;
+    CASE(OP_SENDB, BBB)
+    L_SENDB:
+    {
+      int argc = (c == CALL_MAXARGS) ? -1 : c;
+      int bidx = (argc < 0) ? a+2 : a+c+1;
       mrb_method_t m;
-      struct RClass *c;
+      struct RClass *cls;
       mrb_callinfo *ci = mrb->c->ci;
       mrb_value recv, blk;
       mrb_sym mid = syms[b];
@@ -1417,26 +1351,20 @@ RETRY_TRY_BLOCK:
       mrb_assert(bidx < ci->nregs);
 
       recv = regs[a];
-      if (GET_OPCODE(i) != OP_SENDB) {
-        SET_NIL_VALUE(regs[bidx]);
-        blk = regs[bidx];
-      }
-      else {
-        blk = regs[bidx];
-        if (!mrb_nil_p(blk) && mrb_type(blk) != MRB_TT_PROC) {
-          blk = mrb_convert_type(mrb, blk, MRB_TT_PROC, "Proc", "to_proc");
-          /* The stack might have been reallocated during mrb_convert_type(),
-             see #3622 */
-          regs[bidx] = blk;
-        }
+      blk = regs[bidx];
+      if (!mrb_nil_p(blk) && mrb_type(blk) != MRB_TT_PROC) {
+        blk = mrb_convert_type(mrb, blk, MRB_TT_PROC, "Proc", "to_proc");
+        /* The stack might have been reallocated during mrb_convert_type(),
+           see #3622 */
+        regs[bidx] = blk;
       }
-      c = mrb_class(mrb, recv);
-      m = mrb_method_search_vm(mrb, &c, mid);
+      cls = mrb_class(mrb, recv);
+      m = mrb_method_search_vm(mrb, &cls, mid);
       if (MRB_METHOD_UNDEF_P(m)) {
         mrb_sym missing = mrb_intern_lit(mrb, "method_missing");
-        m = mrb_method_search_vm(mrb, &c, missing);
+        m = mrb_method_search_vm(mrb, &cls, missing);
         if (MRB_METHOD_UNDEF_P(m) || (missing == mrb->c->ci->mid && mrb_obj_eq(mrb, regs[0], recv))) {
-          mrb_value args = (argc < 0) ? regs[a+1] : mrb_ary_new_from_values(mrb, n, regs+a+1);
+          mrb_value args = (argc < 0) ? regs[a+1] : mrb_ary_new_from_values(mrb, c, regs+a+1);
           ERR_PC_SET(mrb, pc);
           mrb_method_missing(mrb, mid, recv, args);
         }
@@ -1444,7 +1372,7 @@ RETRY_TRY_BLOCK:
           if (a+2 >= irep->nregs) {
             mrb_stack_extend(mrb, a+3);
           }
-          regs[a+1] = mrb_ary_new_from_values(mrb, n, regs+a+1);
+          regs[a+1] = mrb_ary_new_from_values(mrb, c, regs+a+1);
           regs[a+2] = blk;
           argc = -1;
         }
@@ -1456,17 +1384,17 @@ RETRY_TRY_BLOCK:
       ci = cipush(mrb);
       ci->mid = mid;
       ci->stackent = mrb->c->stack;
-      ci->target_class = c;
+      ci->target_class = cls;
       ci->argc = argc;
 
-      ci->pc = pc + 1;
+      ci->pc = pc;
       ci->acc = a;
 
       /* prepare stack */
       mrb->c->stack += a;
 
       if (MRB_METHOD_CFUNC_P(m)) {
-        ci->nregs = (argc < 0) ? 3 : n+2;
+        ci->nregs = (argc < 0) ? 3 : c+2;
         if (MRB_METHOD_PROC_P(m)) {
           struct RProc *p = MRB_METHOD_PROC(m);
 
@@ -1480,12 +1408,10 @@ RETRY_TRY_BLOCK:
         mrb_gc_arena_shrink(mrb, ai);
         if (mrb->exc) goto L_RAISE;
         ci = mrb->c->ci;
-        if (GET_OPCODE(i) == OP_SENDB) {
-          if (mrb_type(blk) == MRB_TT_PROC) {
-            struct RProc *p = mrb_proc_ptr(blk);
-            if (p && !MRB_PROC_STRICT_P(p) && MRB_PROC_ENV(p) == ci[-1].env) {
-              p->flags |= MRB_PROC_ORPHAN;
-            }
+        if (mrb_type(blk) == MRB_TT_PROC) {
+          struct RProc *p = mrb_proc_ptr(blk);
+          if (p && !MRB_PROC_STRICT_P(p) && MRB_PROC_ENV(p) == ci[-1].env) {
+            p->flags |= MRB_PROC_ORPHAN;
           }
         }
         if (!ci->target_class) { /* return from context modifying method (resume/yield) */
@@ -1521,14 +1447,7 @@ RETRY_TRY_BLOCK:
       }
     }
 
-    CASE(OP_FSEND) {
-      /* A B C  R(A) := fcall(R(A),Syms(B),R(A+1),... ,R(A+C-1)) */
-      /* not implemented yet */
-      NEXT;
-    }
-
-    CASE(OP_CALL) {
-      /* A      R(A) := self.call(frame.argc, frame.argv) */
+    CASE(OP_CALL, Z) {
       mrb_callinfo *ci;
       mrb_value recv = mrb->c->stack[0];
       struct RProc *m = mrb_proc_ptr(recv);
@@ -1571,7 +1490,9 @@ RETRY_TRY_BLOCK:
         irep = m->body.irep;
         if (!irep) {
           mrb->c->stack[0] = mrb_nil_value();
-          goto L_RETURN;
+          a = 0;
+          c = OP_R_NORMAL;
+          goto L_OP_RETURN_BODY;
         }
         pool = irep->pool;
         syms = irep->syms;
@@ -1593,14 +1514,11 @@ RETRY_TRY_BLOCK:
       }
     }
 
-    CASE(OP_SUPER) {
-      /* A C  R(A) := super(R(A+1),... ,R(A+C+1)) */
-      int a = GETARG_A(i);
-      int n = GETARG_C(i);
-      int argc = (n == CALL_MAXARGS) ? -1 : n;
-      int bidx = (argc < 0) ? a+2 : a+n+1;
+    CASE(OP_SUPER, BB) {
+      int argc = (b == CALL_MAXARGS) ? -1 : b;
+      int bidx = (argc < 0) ? a+2 : a+b+1;
       mrb_method_t m;
-      struct RClass *c;
+      struct RClass *cls;
       mrb_callinfo *ci = mrb->c->ci;
       mrb_value recv, blk;
       mrb_sym mid = ci->mid;
@@ -1636,17 +1554,17 @@ RETRY_TRY_BLOCK:
         regs[bidx] = blk;
         ci = mrb->c->ci;
       }
-      c = target_class->super;
-      m = mrb_method_search_vm(mrb, &c, mid);
+      cls = target_class->super;
+      m = mrb_method_search_vm(mrb, &cls, mid);
       if (MRB_METHOD_UNDEF_P(m)) {
         mrb_sym missing = mrb_intern_lit(mrb, "method_missing");
 
         if (mid != missing) {
-          c = mrb_class(mrb, recv);
+          cls = mrb_class(mrb, recv);
         }
-        m = mrb_method_search_vm(mrb, &c, missing);
+        m = mrb_method_search_vm(mrb, &cls, missing);
         if (MRB_METHOD_UNDEF_P(m)) {
-          mrb_value args = (argc < 0) ? regs[a+1] : mrb_ary_new_from_values(mrb, n, regs+a+1);
+          mrb_value args = (argc < 0) ? regs[a+1] : mrb_ary_new_from_values(mrb, b, regs+a+1);
           ERR_PC_SET(mrb, pc);
           mrb_method_missing(mrb, mid, recv, args);
         }
@@ -1655,7 +1573,7 @@ RETRY_TRY_BLOCK:
           if (a+2 >= ci->nregs) {
             mrb_stack_extend(mrb, a+3);
           }
-          regs[a+1] = mrb_ary_new_from_values(mrb, n, regs+a+1);
+          regs[a+1] = mrb_ary_new_from_values(mrb, b, regs+a+1);
           regs[a+2] = blk;
           argc = -1;
         }
@@ -1666,8 +1584,8 @@ RETRY_TRY_BLOCK:
       ci = cipush(mrb);
       ci->mid = mid;
       ci->stackent = mrb->c->stack;
-      ci->target_class = c;
-      ci->pc = pc + 1;
+      ci->target_class = cls;
+      ci->pc = pc;
       ci->argc = argc;
 
       /* prepare stack */
@@ -1676,7 +1594,7 @@ RETRY_TRY_BLOCK:
 
       if (MRB_METHOD_CFUNC_P(m)) {
         mrb_value v;
-        ci->nregs = (argc < 0) ? 3 : n+2;
+        ci->nregs = (argc < 0) ? 3 : b+2;
         if (MRB_METHOD_PROC_P(m)) {
           ci->proc = MRB_METHOD_PROC(m);
         }
@@ -1720,14 +1638,11 @@ RETRY_TRY_BLOCK:
       }
     }
 
-    CASE(OP_ARGARY) {
-      /* A Bx   R(A) := argument array (16=6:1:5:4) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      int m1 = (bx>>10)&0x3f;
-      int r  = (bx>>9)&0x1;
-      int m2 = (bx>>4)&0x1f;
-      int lv = (bx>>0)&0xf;
+    CASE(OP_ARGARY, BS) {
+      int m1 = (b>>10)&0x3f;
+      int r  = (b>>9)&0x1;
+      int m2 = (b>>4)&0x1f;
+      int lv = (b>>0)&0xf;
       mrb_value *stack;
 
       if (mrb->c->ci->mid == 0 || mrb->c->ci->target_class == NULL) {
@@ -1778,18 +1693,15 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_ENTER) {
-      /* Ax             arg setup according to flags (23=5:5:1:5:5:1:1) */
-      /* number of optional arguments times OP_JMP should follow */
-      mrb_aspec ax = GETARG_Ax(i);
-      int m1 = MRB_ASPEC_REQ(ax);
-      int o  = MRB_ASPEC_OPT(ax);
-      int r  = MRB_ASPEC_REST(ax);
-      int m2 = MRB_ASPEC_POST(ax);
+    CASE(OP_ENTER, W) {
+      int m1 = MRB_ASPEC_REQ(a);
+      int o  = MRB_ASPEC_OPT(a);
+      int r  = MRB_ASPEC_REST(a);
+      int m2 = MRB_ASPEC_POST(a);
       /* unused
-      int k  = MRB_ASPEC_KEY(ax);
-      int kd = MRB_ASPEC_KDICT(ax);
-      int b  = MRB_ASPEC_BLOCK(ax);
+      int k  = MRB_ASPEC_KEY(a);
+      int kd = MRB_ASPEC_KDICT(a);
+      int b  = MRB_ASPEC_BLOCK(a);
       */
       int argc = mrb->c->ci->argc;
       mrb_value *argv = regs+1;
@@ -1841,9 +1753,8 @@ RETRY_TRY_BLOCK:
         if (r) {
           regs[m1+o+1] = mrb_ary_new_capa(mrb, 0);
         }
-        if (o == 0 || argc < m1+m2) pc++;
-        else
-          pc += argc - m1 - m2 + 1;
+        if (o > 0 && argc >= m1+m2)
+          pc += (argc - m1 - m2)*3;
       }
       else {
         int rnum = 0;
@@ -1852,8 +1763,11 @@ RETRY_TRY_BLOCK:
           value_move(&regs[1], argv, m1+o);
         }
         if (r) {
+          mrb_value ary;
+
           rnum = argc-m1-o-m2;
-          regs[m1+o+1] = mrb_ary_new_from_values(mrb, rnum, argv+m1+o);
+          ary = mrb_ary_new_from_values(mrb, rnum, argv+m1+o);
+          regs[m1+o+1] = ary;
         }
         if (m2) {
           if (argc-m2 > m1) {
@@ -1863,7 +1777,7 @@ RETRY_TRY_BLOCK:
         if (argv0 == argv) {
           regs[len+1] = *blk; /* move block */
         }
-        pc += o + 1;
+        pc += o*3;
       }
       mrb->c->ci->argc = len;
       /* clear local (but non-argument) variables */
@@ -1873,24 +1787,33 @@ RETRY_TRY_BLOCK:
       JUMP;
     }
 
-    CASE(OP_KARG) {
-      /* A B C          R(A) := kdict[Syms(B)]; if C kdict.rm(Syms(B)) */
-      /* if C == 2; raise unless kdict.empty? */
-      /* OP_JMP should follow to skip init code */
+    CASE(OP_KARG, BB) {
+      /* not implemented yet */
+      NEXT;
+    }
+    CASE(OP_KARG2, BB) {
+      /* not implemented yet */
       NEXT;
     }
 
-    CASE(OP_KDICT) {
-      /* A C            R(A) := kdict */
+    CASE(OP_KDICT, B) {
+      /* not implemented yet */
       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:
-      i = MKOP_AB(OP_RETURN, GETARG_A(i), OP_R_NORMAL);
-      /* fall through */
-    CASE(OP_RETURN) {
-      /* A B     return R(A) (B=normal,in-block return/break) */
-      mrb_callinfo *ci;
+    {
+       mrb_callinfo *ci;
 
 #define ecall_adjust() do {\
   ptrdiff_t cioff = ci - mrb->c->cibase;\
@@ -1976,7 +1899,7 @@ RETRY_TRY_BLOCK:
           mrb->c->stack = ci[1].stackent;
         }
         mrb_stack_extend(mrb, irep->nregs);
-        pc = mrb->c->rescue[--ci->ridx];
+        pc = irep->iseq+mrb->c->rescue[--ci->ridx];
       }
       else {
         int acc;
@@ -1984,9 +1907,9 @@ RETRY_TRY_BLOCK:
         struct RProc *dst;
 
         ci = mrb->c->ci;
-        v = regs[GETARG_A(i)];
+        v = regs[a];
         mrb_gc_protect(mrb, v);
-        switch (GETARG_B(i)) {
+        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)) {
@@ -2021,8 +1944,7 @@ RETRY_TRY_BLOCK:
             struct mrb_context *c;
 
             if (!mrb->c->prev) { /* toplevel return */
-              localjump_error(mrb, LOCALJUMP_ERROR_RETURN);
-              goto L_RAISE;
+              goto L_STOP;
             }
             if (mrb->c->prev->ci == mrb->c->prev->cibase) {
               mrb_value exc = mrb_exc_new_str_lit(mrb, E_FIBER_ERROR, "double resume");
@@ -2141,91 +2063,11 @@ RETRY_TRY_BLOCK:
       JUMP;
     }
 
-    CASE(OP_TAILCALL) {
-      /* A B C  return call(R(A),Syms(B),R(A+1),... ,R(A+C+1)) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int n = GETARG_C(i);
-      mrb_method_t m;
-      struct RClass *c;
-      mrb_callinfo *ci;
-      mrb_value recv;
-      mrb_sym mid = syms[b];
-
-      recv = regs[a];
-      c = mrb_class(mrb, recv);
-      m = mrb_method_search_vm(mrb, &c, mid);
-      if (MRB_METHOD_UNDEF_P(m)) {
-        mrb_value sym = mrb_symbol_value(mid);
-        mrb_sym missing = mrb_intern_lit(mrb, "method_missing");
-        m = mrb_method_search_vm(mrb, &c, missing);
-        if (MRB_METHOD_UNDEF_P(m)) {
-          mrb_value args;
-
-          if (n == CALL_MAXARGS) {
-            args = regs[a+1];
-          }
-          else {
-            args = mrb_ary_new_from_values(mrb, n, regs+a+1);
-          }
-          ERR_PC_SET(mrb, pc);
-          mrb_method_missing(mrb, mid, recv, args);
-        }
-        mid = missing;
-        if (n == CALL_MAXARGS) {
-          mrb_ary_unshift(mrb, regs[a+1], sym);
-        }
-        else {
-          value_move(regs+a+2, regs+a+1, ++n);
-          regs[a+1] = sym;
-        }
-      }
-
-      /* replace callinfo */
-      ci = mrb->c->ci;
-      ci->mid = mid;
-      ci->target_class = c;
-      if (n == CALL_MAXARGS) {
-        ci->argc = -1;
-      }
-      else {
-        ci->argc = n;
-      }
-
-      /* move stack */
-      value_move(mrb->c->stack, &regs[a], ci->argc+1);
-
-      if (MRB_METHOD_CFUNC_P(m)) {
-        mrb_value v = MRB_METHOD_CFUNC(m)(mrb, recv);
-        mrb->c->stack[0] = v;
-        mrb_gc_arena_restore(mrb, ai);
-        goto L_RETURN;
-      }
-      else {
-        /* setup environment for calling method */
-        struct RProc *p = MRB_METHOD_PROC(m);
-        irep = p->body.irep;
-        pool = irep->pool;
-        syms = irep->syms;
-        if (ci->argc < 0) {
-          mrb_stack_extend(mrb, (irep->nregs < 3) ? 3 : irep->nregs);
-        }
-        else {
-          mrb_stack_extend(mrb, irep->nregs);
-        }
-        pc = irep->iseq;
-      }
-      JUMP;
-    }
-
-    CASE(OP_BLKPUSH) {
-      /* A Bx   R(A) := block (16=6:1:5:4) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
-      int m1 = (bx>>10)&0x3f;
-      int r  = (bx>>9)&0x1;
-      int m2 = (bx>>4)&0x1f;
-      int lv = (bx>>0)&0xf;
+    CASE(OP_BLKPUSH, BS) {
+      int m1 = (b>>10)&0x3f;
+      int r  = (b>>9)&0x1;
+      int m2 = (b>>4)&0x1f;
+      int lv = (b>>0)&0xf;
       mrb_value *stack;
 
       if (lv == 0) stack = regs + 1;
@@ -2251,10 +2093,7 @@ RETRY_TRY_BLOCK:
   v1(regs[a]) = v1(regs[a]) op v2(regs[a+1]);\
 } while(0)
 
-    CASE(OP_ADD) {
-      /* A B C  R(A) := R(A)+R(A+1) (Syms[B]=:+,C=1)*/
-      int a = GETARG_A(i);
-
+    CASE(OP_ADD, BB) {
       /* need to check if op is overridden */
       switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {
       case TYPES2(MRB_TT_FIXNUM,MRB_TT_FIXNUM):
@@ -2308,16 +2147,14 @@ RETRY_TRY_BLOCK:
         regs[a] = mrb_str_plus(mrb, regs[a], regs[a+1]);
         break;
       default:
+        c = 1;
         goto L_SEND;
       }
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_SUB) {
-      /* A B C  R(A) := R(A)-R(A+1) (Syms[B]=:-,C=1)*/
-      int a = GETARG_A(i);
-
+    CASE(OP_SUB, BB) {
       /* need to check if op is overridden */
       switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {
       case TYPES2(MRB_TT_FIXNUM,MRB_TT_FIXNUM):
@@ -2367,15 +2204,13 @@ RETRY_TRY_BLOCK:
         break;
 #endif
       default:
+        c = 1;
         goto L_SEND;
       }
       NEXT;
     }
 
-    CASE(OP_MUL) {
-      /* A B C  R(A) := R(A)*R(A+1) (Syms[B]=:*,C=1)*/
-      int a = GETARG_A(i);
-
+    CASE(OP_MUL, BB) {
       /* need to check if op is overridden */
       switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {
       case TYPES2(MRB_TT_FIXNUM,MRB_TT_FIXNUM):
@@ -2425,14 +2260,13 @@ RETRY_TRY_BLOCK:
         break;
 #endif
       default:
+        c = 1;
         goto L_SEND;
       }
       NEXT;
     }
 
-    CASE(OP_DIV) {
-      /* A B C  R(A) := R(A)/R(A+1) (Syms[B]=:/,C=1)*/
-      int a = GETARG_A(i);
+    CASE(OP_DIV, BB) {
 #ifndef MRB_WITHOUT_FLOAT
       double x, y, f;
 #endif
@@ -2465,6 +2299,7 @@ RETRY_TRY_BLOCK:
         break;
 #endif
       default:
+        c = 1;
         goto L_SEND;
       }
 
@@ -2482,16 +2317,13 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_ADDI) {
-      /* A B C  R(A) := R(A)+C (Syms[B]=:+)*/
-      int a = GETARG_A(i);
-
+    CASE(OP_ADDI, BBB) {
       /* need to check if + is overridden */
       switch (mrb_type(regs[a])) {
       case MRB_TT_FIXNUM:
         {
           mrb_int x = mrb_fixnum(regs[a]);
-          mrb_int y = GETARG_C(i);
+          mrb_int y = (mrb_int)c;
           mrb_int z;
 
           if (mrb_int_add_overflow(x, y, &z)) {
@@ -2508,24 +2340,22 @@ RETRY_TRY_BLOCK:
 #ifdef MRB_WORD_BOXING
         {
           mrb_float x = mrb_float(regs[a]);
-          SET_FLOAT_VALUE(mrb, regs[a], x + GETARG_C(i));
+          SET_FLOAT_VALUE(mrb, regs[a], x + c);
         }
 #else
-        mrb_float(regs[a]) += GETARG_C(i);
+        mrb_float(regs[a]) += c;
 #endif
         break;
 #endif
       default:
-        SET_INT_VALUE(regs[a+1], GETARG_C(i));
-        i = MKOP_ABC(OP_SEND, a, GETARG_B(i), 1);
+        SET_INT_VALUE(regs[a+1], c);
+        c = 1;
         goto L_SEND;
       }
       NEXT;
     }
 
-    CASE(OP_SUBI) {
-      /* A B C  R(A) := R(A)-C (Syms[B]=:-)*/
-      int a = GETARG_A(i);
+    CASE(OP_SUBI, BBB) {
       mrb_value *regs_a = regs + a;
 
       /* need to check if + is overridden */
@@ -2533,7 +2363,7 @@ RETRY_TRY_BLOCK:
       case MRB_TT_FIXNUM:
         {
           mrb_int x = mrb_fixnum(regs_a[0]);
-          mrb_int y = GETARG_C(i);
+          mrb_int y = (mrb_int)c;
           mrb_int z;
 
           if (mrb_int_sub_overflow(x, y, &z)) {
@@ -2553,13 +2383,13 @@ RETRY_TRY_BLOCK:
           SET_FLOAT_VALUE(mrb, regs[a], x - GETARG_C(i));
         }
 #else
-        mrb_float(regs_a[0]) -= GETARG_C(i);
+        mrb_float(regs_a[0]) -= c;
 #endif
         break;
 #endif
       default:
-        SET_INT_VALUE(regs_a[1], GETARG_C(i));
-        i = MKOP_ABC(OP_SEND, a, GETARG_B(i), 1);
+        SET_INT_VALUE(regs_a[1], c);
+        c = 1;
         goto L_SEND;
       }
       NEXT;
@@ -2576,6 +2406,7 @@ RETRY_TRY_BLOCK:
     result = OP_CMP_BODY(op,mrb_fixnum,mrb_fixnum);\
     break;\
   default:\
+    c = 1;\
     goto L_SEND;\
   }\
   if (result) {\
@@ -2603,6 +2434,7 @@ RETRY_TRY_BLOCK:
     result = OP_CMP_BODY(op,mrb_float,mrb_float);\
     break;\
   default:\
+    c = 1;\
     goto L_SEND;\
   }\
   if (result) {\
@@ -2614,9 +2446,7 @@ RETRY_TRY_BLOCK:
 } while(0)
 #endif
 
-    CASE(OP_EQ) {
-      /* A B C  R(A) := R(A)==R(A+1) (Syms[B]=:==,C=1)*/
-      int a = GETARG_A(i);
+    CASE(OP_EQ, BB) {
       if (mrb_obj_eq(mrb, regs[a], regs[a+1])) {
         SET_TRUE_VALUE(regs[a]);
       }
@@ -2626,68 +2456,59 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_LT) {
-      /* A B C  R(A) := R(A)<R(A+1) (Syms[B]=:<,C=1)*/
-      int a = GETARG_A(i);
+    CASE(OP_LT, BB) {
       OP_CMP(<);
       NEXT;
     }
 
-    CASE(OP_LE) {
-      /* A B C  R(A) := R(A)<=R(A+1) (Syms[B]=:<=,C=1)*/
-      int a = GETARG_A(i);
+    CASE(OP_LE, BB) {
       OP_CMP(<=);
       NEXT;
     }
 
-    CASE(OP_GT) {
-      /* A B C  R(A) := R(A)>R(A+1) (Syms[B]=:>,C=1)*/
-      int a = GETARG_A(i);
+    CASE(OP_GT, BB) {
       OP_CMP(>);
       NEXT;
     }
 
-    CASE(OP_GE) {
-      /* A B C  R(A) := R(A)>=R(A+1) (Syms[B]=:>=,C=1)*/
-      int a = GETARG_A(i);
+    CASE(OP_GE, BB) {
       OP_CMP(>=);
       NEXT;
     }
 
-    CASE(OP_ARRAY) {
-      /* A B C          R(A) := ary_new(R(B),R(B+1)..R(B+C)) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
+    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) {
-      /* A B            mrb_ary_concat(R(A),R(B)) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      mrb_value splat = mrb_ary_splat(mrb, regs[b]);
+    CASE(OP_ARYCAT, B) {
+      mrb_value splat = mrb_ary_splat(mrb, regs[a+1]);
       mrb_ary_concat(mrb, regs[a], splat);
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_ARYPUSH) {
-      /* A B            R(A).push(R(B)) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      mrb_ary_push(mrb, regs[a], regs[b]);
+    CASE(OP_ARYPUSH, B) {
+      mrb_ary_push(mrb, regs[a], regs[a+1]);
       NEXT;
     }
 
-    CASE(OP_AREF) {
-      /* A B C          R(A) := R(B)[C] */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
+    CASE(OP_ARYDUP, B) {
+      mrb_value ary = regs[a];
+      ary = mrb_ary_new_from_values(mrb, RARRAY_LEN(ary), RARRAY_PTR(ary));
+      regs[a] = ary;
+      NEXT;
+    }
+
+    CASE(OP_AREF, BBB) {
       mrb_value v = regs[b];
 
       if (!mrb_array_p(v)) {
@@ -2705,21 +2526,15 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_ASET) {
-      /* A B C          R(B)[C] := R(A) */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
+    CASE(OP_ASET, BBB) {
       mrb_ary_set(mrb, regs[b], c, regs[a]);
       NEXT;
     }
 
-    CASE(OP_APOST) {
-      /* A B C  *R(A),R(A+1)..R(A+C) := R(A)[B..] */
-      int a = GETARG_A(i);
+    CASE(OP_APOST, BBB) {
       mrb_value v = regs[a];
-      int pre  = GETARG_B(i);
-      int post = GETARG_C(i);
+      int pre  = b;
+      int post = c;
       struct RArray *ary;
       int len, idx;
 
@@ -2750,48 +2565,58 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_STRING) {
-      /* A Bx           R(A) := str_new(Lit(Bx)) */
-      mrb_int a = GETARG_A(i);
-      mrb_int bx = GETARG_Bx(i);
-      mrb_value str = mrb_str_dup(mrb, pool[bx]);
+    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) {
+      mrb_value str = mrb_str_dup(mrb, pool[b]);
 
       regs[a] = str;
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_STRCAT) {
-      /* A B    R(A).concat(R(B)) */
-      mrb_int a = GETARG_A(i);
-      mrb_int b = GETARG_B(i);
+    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;
 
-      mrb_str_concat(mrb, regs[a], regs[b]);
+      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_HASH) {
-      /* A B C   R(A) := hash_new(R(B),R(B+1)..R(B+C)) */
-      int b = GETARG_B(i);
-      int c = GETARG_C(i);
-      int lim = b+c*2;
-      mrb_value hash = mrb_hash_new_capa(mrb, c);
+    CASE(OP_HASHADD, BB) {
+      mrb_value hash = regs[a];
+      int i;
+      int lim = a+b*2+1;
 
-      while (b < lim) {
-        mrb_hash_set(mrb, hash, regs[b], regs[b+1]);
+      for (i=a+1; i<lim; i++) {
+        mrb_hash_set(mrb, hash, regs[i], regs[i+1]);
         b+=2;
       }
-      regs[GETARG_A(i)] = hash;
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_LAMBDA) {
-      /* A b c  R(A) := lambda(SEQ[b],c) (b:c = 14:2) */
+    CASE(OP_LAMBDA, BB)
+    c = OP_L_LAMBDA;
+    L_MAKE_LAMBDA:
+    {
       struct RProc *p;
-      int a = GETARG_A(i);
-      int b = GETARG_b(i);
-      int c = GETARG_c(i);
       mrb_irep *nirep = irep->reps[b];
 
       if (c & OP_L_CAPTURE) {
@@ -2806,19 +2631,38 @@ RETRY_TRY_BLOCK:
       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_OCLASS) {
-      /* A      R(A) := ::Object */
-      regs[GETARG_A(i)] = mrb_obj_value(mrb->object_class);
+    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_CLASS) {
-      /* A B    R(A) := newclass(R(A),Syms(B),R(A+1)) */
+    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;
-      int a = GETARG_A(i);
       mrb_value base, super;
-      mrb_sym id = syms[GETARG_B(i)];
+      mrb_sym id = syms[b];
 
       base = regs[a];
       super = regs[a+1];
@@ -2832,32 +2676,27 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_MODULE) {
-      /* A B            R(A) := newmodule(R(A),Syms(B)) */
-      struct RClass *c = 0, *baseclass;
-      int a = GETARG_A(i);
+    CASE(OP_MODULE, BB) {
+      struct RClass *cls = 0, *baseclass;
       mrb_value base;
-      mrb_sym id = syms[GETARG_B(i)];
+      mrb_sym id = syms[b];
 
       base = regs[a];
       if (mrb_nil_p(base)) {
         baseclass = MRB_PROC_TARGET_CLASS(mrb->c->ci->proc);
         base = mrb_obj_value(baseclass);
       }
-      c = mrb_vm_define_module(mrb, base, id);
-      regs[a] = mrb_obj_value(c);
+      cls = mrb_vm_define_module(mrb, base, id);
+      regs[a] = mrb_obj_value(cls);
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_EXEC) {
-      /* A Bx   R(A) := blockexec(R(A),SEQ[Bx]) */
-      int a = GETARG_A(i);
-      int bx = GETARG_Bx(i);
+    CASE(OP_EXEC, BB) {
       mrb_callinfo *ci;
       mrb_value recv = regs[a];
       struct RProc *p;
-      mrb_irep *nirep = irep->reps[bx];
+      mrb_irep *nirep = irep->reps[b];
 
       /* prepare closure */
       p = mrb_proc_new(mrb, nirep);
@@ -2868,7 +2707,7 @@ RETRY_TRY_BLOCK:
 
       /* prepare call stack */
       ci = cipush(mrb);
-      ci->pc = pc + 1;
+      ci->pc = pc;
       ci->acc = a;
       ci->mid = 0;
       ci->stackent = mrb->c->stack;
@@ -2891,56 +2730,53 @@ RETRY_TRY_BLOCK:
       JUMP;
     }
 
-    CASE(OP_METHOD) {
-      /* A B            R(A).newmethod(Syms(B),R(A+1)) */
-      int a = GETARG_A(i);
-      struct RClass *c = mrb_class_ptr(regs[a]);
+    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_METHOD_FROM_PROC(m, p);
-      mrb_define_method_raw(mrb, c, syms[GETARG_B(i)], m);
+      mrb_define_method_raw(mrb, target, syms[b], m);
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_SCLASS) {
-      /* A B    R(A) := R(B).singleton_class */
-      int a = GETARG_A(i);
-      int b = GETARG_B(i);
-
-      regs[a] = mrb_singleton_class(mrb, regs[b]);
+    CASE(OP_SCLASS, B) {
+      regs[a] = mrb_singleton_class(mrb, regs[a]);
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_TCLASS) {
-      /* A      R(A) := target_class */
-      if (!mrb->c->ci->target_class) {
-        mrb_value exc = mrb_exc_new_str_lit(mrb, E_TYPE_ERROR, "no target class or module");
-        mrb_exc_set(mrb, exc);
-        goto L_RAISE;
-      }
-      regs[GETARG_A(i)] = mrb_obj_value(mrb->c->ci->target_class);
+    CASE(OP_TCLASS, B) {
+      if (!check_target_class(mrb)) goto L_RAISE;
+      regs[a] = mrb_obj_value(mrb->c->ci->target_class);
       NEXT;
     }
 
-    CASE(OP_RANGE) {
-      /* A B C  R(A) := range_new(R(B),R(B+1),C) */
-      int b = GETARG_B(i);
-      mrb_value val = mrb_range_new(mrb, regs[b], regs[b+1], GETARG_C(i));
-      regs[GETARG_A(i)] = val;
-      mrb_gc_arena_restore(mrb, ai);
+    CASE(OP_ALIAS, BB) {
+      struct RClass *target;
+
+      if (!check_target_class(mrb)) goto L_RAISE;
+      target = mrb->c->ci->target_class;
+      mrb_alias_method(mrb, target, syms[a], syms[b]);
+      NEXT;
+    }
+    CASE(OP_UNDEF, B) {
+      struct RClass *target;
+
+      if (!check_target_class(mrb)) goto L_RAISE;
+      target = mrb->c->ci->target_class;
+      mrb_undef_method_id(mrb, target, syms[a]);
       NEXT;
     }
 
-    CASE(OP_DEBUG) {
-      /* A B C    debug print R(A),R(B),R(C) */
+    CASE(OP_DEBUG, Z) {
+      FETCH_BBB();
 #ifdef MRB_ENABLE_DEBUG_HOOK
       mrb->debug_op_hook(mrb, irep, pc, regs);
 #else
 #ifndef MRB_DISABLE_STDIO
-      printf("OP_DEBUG %d %d %d\n", GETARG_A(i), GETARG_B(i), GETARG_C(i));
+      printf("OP_DEBUG %d %d %d\n", a, b, c);
 #else
       abort();
 #endif
@@ -2948,7 +2784,48 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_STOP) {
+    CASE(OP_ERR, B) {
+      mrb_value msg = mrb_str_dup(mrb, pool[a]);
+      mrb_value exc;
+
+      exc = mrb_exc_new_str(mrb, E_LOCALJUMP_ERROR, msg);
+      ERR_PC_SET(mrb, pc);
+      mrb_exc_set(mrb, exc);
+      goto L_RAISE;
+    }
+
+    CASE(OP_EXT1, Z) {
+      insn = READ_B();
+      switch (insn) {
+#define OPCODE(insn,ops) case OP_ ## insn: FETCH_ ## ops ## _1(); 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(); 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(); goto L_OP_ ## insn ## _BODY;
+#include "mruby/ops.h"
+#undef OPCODE
+      }
+      pc--;
+      NEXT;
+    }
+
+    CASE(OP_STOP, Z) {
       /*        stop VM */
     L_STOP:
       while (mrb->c->eidx > 0) {
@@ -2961,26 +2838,9 @@ RETRY_TRY_BLOCK:
       }
       return regs[irep->nlocals];
     }
-
-    CASE(OP_ERR) {
-      /* Bx     raise RuntimeError with message Lit(Bx) */
-      mrb_value msg = mrb_str_dup(mrb, pool[GETARG_Bx(i)]);
-      mrb_value exc;
-
-      if (GETARG_A(i) == 0) {
-        exc = mrb_exc_new_str(mrb, E_RUNTIME_ERROR, msg);
-      }
-      else {
-        exc = mrb_exc_new_str(mrb, E_LOCALJUMP_ERROR, msg);
-      }
-      ERR_PC_SET(mrb, pc);
-      mrb_exc_set(mrb, exc);
-      goto L_RAISE;
-    }
   }
   END_DISPATCH;
 #undef regs
-
   }
   MRB_CATCH(&c_jmp) {
     exc_catched = TRUE;