Merge pull request #4151 from take-cheeze/remove_op_symidx

Reduce instruction size

7 files changed, 191 insertions, 102 deletions

diff --git a/doc/opcode.md b/doc/opcode.md
index fea0afafd..eab82a26f 100644
--- a/doc/opcode.md
+++ b/doc/opcode.md
@@ -84,17 +84,17 @@ with `"`, either `OP_EXT1` or `OP_EXT2` or `OP_EXT2` can be prefixed.
 |OP_RETURN_BLK'   |B            |return R(a) (in-block return)
 |OP_BREAK'        |B            |break R(a)
 |OP_BLKPUSH'      |BS           |R(a) = block (16=5:1:5:1:4)
-|OP_ADD"          |BB           |R(a) = R(a)+R(a+1) (Syms[b]=:+)
-|OP_ADDI"         |BBB          |R(a) = R(a)+mrb_int(c) (Syms[b]=:+)
-|OP_SUB"          |BB           |R(a) = R(a)-R(a+1) (Syms[b]=:-)
-|OP_SUBI"         |BB           |R(a) = R(a)-C (Syms[b]=:-)
-|OP_MUL"          |BB           |R(a) = R(a)*R(a+1) (Syms[b]=:*)
-|OP_DIV"          |BB           |R(a) = R(a)/R(a+1) (Syms[b]=:/)
-|OP_EQ"           |BB           |R(a) = R(a)==R(a+1) (Syms[b]=:==)
-|OP_LT"           |BB           |R(a) = R(a)<R(a+1)  (Syms[b]=:<)
-|OP_LE"           |BB           |R(a) = R(a)<=R(a+1) (Syms[b]=:<=)
-|OP_GT"           |BB           |R(a) = R(a)>R(a+1)  (Syms[b]=:>)
-|OP_GE"           |BB           |R(a) = R(a)>=R(a+1) (Syms[b]=:>=)
+|OP_ADD"          |BB           |R(a) = R(a)+R(a+1)
+|OP_ADDI"         |BBB          |R(a) = R(a)+mrb_int(c)
+|OP_SUB"          |BB           |R(a) = R(a)-R(a+1)
+|OP_SUBI"         |BB           |R(a) = R(a)-C
+|OP_MUL"          |BB           |R(a) = R(a)*R(a+1)
+|OP_DIV"          |BB           |R(a) = R(a)/R(a+1)
+|OP_EQ"           |BB           |R(a) = R(a)==R(a+1)
+|OP_LT"           |BB           |R(a) = R(a)<R(a+1)
+|OP_LE"           |BB           |R(a) = R(a)<=R(a+1)
+|OP_GT"           |BB           |R(a) = R(a)>R(a+1)
+|OP_GE"           |BB           |R(a) = R(a)>=R(a+1)
 |OP_ARRAY'        |BB           |R(a) = ary_new(R(a),R(a+1)..R(a+b))
 |OP_ARRAY2"       |BB           |R(a) = ary_new(R(b),R(b+1)..R(b+c))
 |OP_ARYCAT'       |B            |ary_cat(R(a),R(a+1))
diff --git a/include/mruby/ops.h b/include/mruby/ops.h
index f23bb1b0b..7531a5ee2 100644
--- a/include/mruby/ops.h
+++ b/include/mruby/ops.h
@@ -70,17 +70,17 @@ OPCODE(RETURN,     B)        /* return R(a) (normal) */
 OPCODE(RETURN_BLK, B)        /* return R(a) (in-block return) */
 OPCODE(BREAK,      B)        /* break R(a) */
 OPCODE(BLKPUSH,    BS)       /* R(a) = block (16=m5:r1:m5:d1:lv4) */
-OPCODE(ADD,        BB)       /* R(a) = R(a)+R(a+1) (Syms[b]=:+) */
-OPCODE(ADDI,       BBB)      /* R(a) = R(a)+mrb_int(c) (Syms[b]=:+) */
-OPCODE(SUB,        BB)       /* R(a) = R(a)-R(a+1) (Syms[b]=:-) */
-OPCODE(SUBI,       BBB)      /* R(a) = R(a)-C (Syms[b]=:-) */
-OPCODE(MUL,        BB)       /* R(a) = R(a)*R(a+1) (Syms[b]=:*) */
-OPCODE(DIV,        BB)       /* R(a) = R(a)/R(a+1) (Syms[b]=:/) */
-OPCODE(EQ,         BB)       /* R(a) = R(a)==R(a+1) (Syms[b]=:==) */
-OPCODE(LT,         BB)       /* R(a) = R(a)<R(a+1)  (Syms[b]=:<) */
-OPCODE(LE,         BB)       /* R(a) = R(a)<=R(a+1) (Syms[b]=:<=) */
-OPCODE(GT,         BB)       /* R(a) = R(a)>R(a+1)  (Syms[b]=:>) */
-OPCODE(GE,         BB)       /* R(a) = R(a)>=R(a+1) (Syms[b]=:>=) */
+OPCODE(ADD,        B)        /* R(a) = R(a)+R(a+1) */
+OPCODE(ADDI,       BB)       /* R(a) = R(a)+mrb_int(c)  */
+OPCODE(SUB,        B)        /* R(a) = R(a)-R(a+1) */
+OPCODE(SUBI,       BB)       /* R(a) = R(a)-C */
+OPCODE(MUL,        B)        /* R(a) = R(a)*R(a+1) */
+OPCODE(DIV,        B)        /* R(a) = R(a)/R(a+1) */
+OPCODE(EQ,         B)        /* R(a) = R(a)==R(a+1) */
+OPCODE(LT,         B)        /* R(a) = R(a)<R(a+1) */
+OPCODE(LE,         B)        /* R(a) = R(a)<=R(a+1) */
+OPCODE(GT,         B)        /* R(a) = R(a)>R(a+1) */
+OPCODE(GE,         B)        /* R(a) = R(a)>=R(a+1) */
 OPCODE(ARRAY,      BB)       /* R(a) = ary_new(R(a),R(a+1)..R(a+b)) */
 OPCODE(ARRAY2,     BBB)      /* R(a) = ary_new(R(b),R(b+1)..R(b+c)) */
 OPCODE(ARYCAT,     B)        /* ary_cat(R(a),R(a+1)) */
diff --git a/include/mruby/symbol.h b/include/mruby/symbol.h
new file mode 100644
index 000000000..b0feccc51
--- /dev/null
+++ b/include/mruby/symbol.h
@@ -0,0 +1,40 @@
+/*
+** mruby/symbol.h - symbol utilities
+**
+** See Copyright Notice in mruby.h
+*/
+
+#ifndef MRUBY_SYMBOL_H
+#define MRUBY_SYMBOL_H
+
+#include "common.h"
+
+/**
+ * Symbol utilities
+ */
+MRB_BEGIN_DECL
+
+typedef enum mrb_reserved_symbol {
+  mrb_sym_null = 0, // NULL symbol
+
+  mrb_sym_add = 1, // +
+  mrb_sym_sub = 2, // -
+  mrb_sym_mul = 3, // *
+  mrb_sym_div = 4, // /
+  mrb_sym_eq = 5, // ==
+  mrb_sym_lt = 6, // <
+  mrb_sym_le = 7, // <=
+  mrb_sym_gt = 8, // >
+  mrb_sym_ge = 9, // >=
+
+  mrb_sym_method_missing = 10, // method_missing
+} mrb_reserved_symbol;
+
+static inline mrb_bool
+mrb_symbol_constsym_send_p(mrb_sym sym) {
+  return mrb_sym_add <= sym && sym <= mrb_sym_ge;
+}
+
+MRB_END_DECL
+
+#endif  /* MRUBY_SYMBOL_H */
diff --git a/mrbgems/mruby-compiler/core/codegen.c b/mrbgems/mruby-compiler/core/codegen.c
index 8ab1b9bc3..22ac51239 100644
--- a/mrbgems/mruby-compiler/core/codegen.c
+++ b/mrbgems/mruby-compiler/core/codegen.c
@@ -18,6 +18,7 @@
 #include <mruby/opcode.h>
 #include <mruby/re.h>
 #include <mruby/throw.h>
+#include <mruby/symbol.h>
 
 #ifndef MRB_CODEGEN_LEVEL_MAX
 #define MRB_CODEGEN_LEVEL_MAX 1024
@@ -468,11 +469,11 @@ gen_return(codegen_scope *s, uint8_t op, uint16_t src)
 }
 
 static void
-gen_addsub(codegen_scope *s, uint8_t op, uint16_t dst, uint16_t idx)
+gen_addsub(codegen_scope *s, uint8_t op, uint16_t dst)
 {
   if (no_peephole(s)) {
   normal:
-    genop_2(s, op, dst, idx);
+    genop_1(s, op, dst);
     return;
   }
   else {
@@ -493,10 +494,10 @@ gen_addsub(codegen_scope *s, uint8_t op, uint16_t dst, uint16_t idx)
       if (data.b >= 128) goto normal;
       s->pc = s->lastpc;
       if (op == OP_ADD) {
-        genop_3(s, OP_ADDI, dst, idx, (uint8_t)data.b);
+        genop_2(s, OP_ADDI, dst, (uint8_t)data.b);
       }
       else {
-        genop_3(s, OP_SUBI, dst, idx, (uint8_t)data.b);
+        genop_2(s, OP_SUBI, dst, (uint8_t)data.b);
       }
       break;
     default:
@@ -982,7 +983,9 @@ gen_call(codegen_scope *s, node *tree, mrb_sym name, int sp, int val, int safe)
     gen_move(s, cursp(), recv, 1);
     skip = genjmp2(s, OP_JMPNIL, cursp(), 0, val);
   }
-  idx = new_sym(s, sym);
+  if (!mrb_symbol_constsym_send_p(sym)) {
+    idx = new_sym(s, sym);
+  }
   tree = tree->cdr->cdr->car;
   if (tree) {
     n = gen_values(s, tree->car, VAL, sp?1:0);
@@ -1017,31 +1020,31 @@ gen_call(codegen_scope *s, node *tree, mrb_sym name, int sp, int val, int safe)
     const char *symname = mrb_sym2name_len(s->mrb, sym, &symlen);
 
     if (!noop && symlen == 1 && symname[0] == '+' && n == 1)  {
-      gen_addsub(s, OP_ADD, cursp(), idx);
+      gen_addsub(s, OP_ADD, cursp());
     }
     else if (!noop && symlen == 1 && symname[0] == '-' && n == 1)  {
-      gen_addsub(s, OP_SUB, cursp(), idx);
+      gen_addsub(s, OP_SUB, cursp());
     }
     else if (!noop && symlen == 1 && symname[0] == '*' && n == 1)  {
-      genop_2(s, OP_MUL, cursp(), idx);
+      genop_1(s, OP_MUL, cursp());
     }
     else if (!noop && symlen == 1 && symname[0] == '/' && n == 1)  {
-      genop_2(s, OP_DIV, cursp(), idx);
+      genop_1(s, OP_DIV, cursp());
     }
     else if (!noop && symlen == 1 && symname[0] == '<' && n == 1)  {
-      genop_2(s, OP_LT, cursp(), idx);
+      genop_1(s, OP_LT, cursp());
     }
     else if (!noop && symlen == 2 && symname[0] == '<' && symname[1] == '=' && n == 1)  {
-      genop_2(s, OP_LE, cursp(), idx);
+      genop_1(s, OP_LE, cursp());
     }
     else if (!noop && symlen == 1 && symname[0] == '>' && n == 1)  {
-      genop_2(s, OP_GT, cursp(), idx);
+      genop_1(s, OP_GT, cursp());
     }
     else if (!noop && symlen == 2 && symname[0] == '>' && symname[1] == '=' && n == 1)  {
-      genop_2(s, OP_GE, cursp(), idx);
+      genop_1(s, OP_GE, cursp());
     }
     else if (!noop && symlen == 2 && symname[0] == '=' && symname[1] == '=' && n == 1)  {
-      genop_2(s, OP_EQ, cursp(), idx);
+      genop_1(s, OP_EQ, cursp());
     }
     else {
       if (sendv) {
@@ -2023,30 +2026,32 @@ codegen(codegen_scope *s, node *tree, int val)
       push(); pop();
       pop(); pop();
 
-      idx = new_sym(s, sym);
+      if (!mrb_symbol_constsym_send_p(sym)) {
+        idx = new_sym(s, sym);
+      }
       if (len == 1 && name[0] == '+')  {
-        gen_addsub(s, OP_ADD, cursp(), idx);
+        gen_addsub(s, OP_ADD, cursp());
       }
       else if (len == 1 && name[0] == '-')  {
-        gen_addsub(s, OP_SUB, cursp(), idx);
+        gen_addsub(s, OP_SUB, cursp());
       }
       else if (len == 1 && name[0] == '*')  {
-        genop_2(s, OP_MUL, cursp(), idx);
+        genop_1(s, OP_MUL, cursp());
       }
       else if (len == 1 && name[0] == '/')  {
-        genop_2(s, OP_DIV, cursp(), idx);
+        genop_1(s, OP_DIV, cursp());
       }
       else if (len == 1 && name[0] == '<')  {
-        genop_2(s, OP_LT, cursp(), idx);
+        genop_1(s, OP_LT, cursp());
       }
       else if (len == 2 && name[0] == '<' && name[1] == '=')  {
-        genop_2(s, OP_LE, cursp(), idx);
+        genop_1(s, OP_LE, cursp());
       }
       else if (len == 1 && name[0] == '>')  {
-        genop_2(s, OP_GT, cursp(), idx);
+        genop_1(s, OP_GT, cursp());
       }
       else if (len == 2 && name[0] == '>' && name[1] == '=')  {
-        genop_2(s, OP_GE, cursp(), idx);
+        genop_1(s, OP_GE, cursp());
       }
       else {
         genop_3(s, OP_SEND, cursp(), idx, 1);
diff --git a/src/codedump.c b/src/codedump.c
index 30a14f937..7d1950f75 100644
--- a/src/codedump.c
+++ b/src/codedump.c
@@ -328,38 +328,38 @@ codedump(mrb_state *mrb, mrb_irep *irep)
     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]));
+    CASE(OP_ADD, B):
+      printf("OP_ADD\tR%d\t\n", a);
       break;
-    CASE(OP_ADDI, BBB):
-      printf("OP_ADDI\tR%d\t:%s\t%d\n", a, mrb_sym2name(mrb, irep->syms[b]), c);
+    CASE(OP_ADDI, BB):
+      printf("OP_ADDI\tR%d\t%d\n", a, b);
       break;
-    CASE(OP_SUB, BB):
-      printf("OP_SUB\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_SUB, B):
+      printf("OP_SUB\tR%d\t\n", a);
       break;
-    CASE(OP_SUBI, BBB):
-      printf("OP_SUBI\tR%d\t:%s\t%d\n", a, mrb_sym2name(mrb, irep->syms[b]), c);
+    CASE(OP_SUBI, BB):
+      printf("OP_SUBI\tR%d\t%d\n", a, b);
       break;
-    CASE(OP_MUL, BB):
-      printf("OP_MUL\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_MUL, B):
+      printf("OP_MUL\tR%d\t\n", a);
       break;
-    CASE(OP_DIV, BB):
-      printf("OP_DIV\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_DIV, B):
+      printf("OP_DIV\tR%d\t\n", a);
       break;
-    CASE(OP_LT, BB):
-      printf("OP_LT\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_LT, B):
+      printf("OP_LT\t\tR%d\t\n", a);
       break;
-    CASE(OP_LE, BB):
-      printf("OP_LE\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_LE, B):
+      printf("OP_LE\t\tR%d\t\n", a);
       break;
-    CASE(OP_GT, BB):
-      printf("OP_GT\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_GT, B):
+      printf("OP_GT\t\tR%d\t\n", a);
       break;
-    CASE(OP_GE, BB):
-      printf("OP_GE\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_GE, B):
+      printf("OP_GE\t\tR%d\t\n", a);
       break;
-    CASE(OP_EQ, BB):
-      printf("OP_EQ\t\tR%d\t:%s\t\n", a, mrb_sym2name(mrb, irep->syms[b]));
+    CASE(OP_EQ, B):
+      printf("OP_EQ\t\tR%d\t\n", a);
       break;
     CASE(OP_ARRAY, BB):
       printf("OP_ARRAY\tR%d\t%d\t", a, b);
diff --git a/src/symbol.c b/src/symbol.c
index 6b4c7200c..8ec300e20 100644
--- a/src/symbol.c
+++ b/src/symbol.c
@@ -11,6 +11,7 @@
 #include <mruby/string.h>
 #include <mruby/dump.h>
 #include <mruby/class.h>
+#include <mruby/symbol.h>
 
 /* ------------------------------------------------------ */
 typedef struct symbol_name {
@@ -170,10 +171,35 @@ mrb_free_symtbl(mrb_state *mrb)
   kh_destroy(n2s, mrb, mrb->name2sym);
 }
 
+struct reserved_symbol_t {
+  mrb_reserved_symbol sym;
+  char const *str;
+};
+
+static struct reserved_symbol_t reserved_symbols[] = {
+  { mrb_sym_add, "+" },
+  { mrb_sym_sub, "-" },
+  { mrb_sym_mul, "*" },
+  { mrb_sym_div, "/" },
+  { mrb_sym_eq, "==" },
+  { mrb_sym_lt, "<" },
+  { mrb_sym_le, "<=" },
+  { mrb_sym_gt, ">" },
+  { mrb_sym_ge, ">=" },
+  { mrb_sym_method_missing, "method_missing" },
+  { mrb_sym_null, NULL },
+};
+
 void
 mrb_init_symtbl(mrb_state *mrb)
 {
+  int i;
   mrb->name2sym = kh_init(n2s, mrb);
+
+  for (i = 0; reserved_symbols[i].sym != mrb_sym_null; ++i) {
+    mrb_sym s = mrb_intern_static(mrb, reserved_symbols[i].str, strlen(reserved_symbols[i].str));
+    mrb_assert(s == reserved_symbols[i].sym);
+  }
 }
 
 /**********************************************************************
diff --git a/src/vm.c b/src/vm.c
index 8157f6ca0..627eb9325 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -21,6 +21,7 @@
 #include <mruby/opcode.h>
 #include "value_array.h"
 #include <mruby/throw.h>
+#include <mruby/symbol.h>
 
 #ifdef MRB_DISABLE_STDIO
 #if defined(__cplusplus)
@@ -1009,6 +1010,7 @@ mrb_vm_exec(mrb_state *mrb, struct RProc *proc, mrb_code *pc)
   uint32_t a;
   uint16_t b;
   uint8_t c;
+  mrb_sym mid;
 
 #ifdef DIRECT_THREADED
   static void *optable[] = {
@@ -1386,9 +1388,18 @@ RETRY_TRY_BLOCK:
       SET_NIL_VALUE(regs[bidx]);
       goto L_SENDB;
     };
+    L_SEND_CONSTSYM:
+    {
+      /* push nil after arguments */
+      int bidx = (c == CALL_MAXARGS) ? a+2 : a+c+1;
+      SET_NIL_VALUE(regs[bidx]);
+      goto L_SENDB_CONSTSYM;
+    };
 
     CASE(OP_SENDB, BBB)
     L_SENDB:
+    mid = syms[b];
+    L_SENDB_CONSTSYM:
     {
       int argc = (c == CALL_MAXARGS) ? -1 : c;
       int bidx = (argc < 0) ? a+2 : a+c+1;
@@ -1396,7 +1407,6 @@ RETRY_TRY_BLOCK:
       struct RClass *cls;
       mrb_callinfo *ci = mrb->c->ci;
       mrb_value recv, blk;
-      mrb_sym mid = syms[b];
 
       mrb_assert(bidx < irep->nregs);
 
@@ -2204,7 +2214,7 @@ RETRY_TRY_BLOCK:
   v1(regs[a]) = v1(regs[a]) op v2(regs[a+1]);\
 } while(0)
 
-    CASE(OP_ADD, BB) {
+    CASE(OP_ADD, B) {
       /* 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):
@@ -2259,13 +2269,14 @@ RETRY_TRY_BLOCK:
         break;
       default:
         c = 1;
-        goto L_SEND;
+        mid = mrb_sym_add;
+        goto L_SEND_CONSTSYM;
       }
       mrb_gc_arena_restore(mrb, ai);
       NEXT;
     }
 
-    CASE(OP_SUB, BB) {
+    CASE(OP_SUB, B) {
       /* 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):
@@ -2316,12 +2327,13 @@ RETRY_TRY_BLOCK:
 #endif
       default:
         c = 1;
-        goto L_SEND;
+        mid = mrb_sym_sub;
+        goto L_SEND_CONSTSYM;
       }
       NEXT;
     }
 
-    CASE(OP_MUL, BB) {
+    CASE(OP_MUL, B) {
       /* 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):
@@ -2372,12 +2384,13 @@ RETRY_TRY_BLOCK:
 #endif
       default:
         c = 1;
-        goto L_SEND;
+        mid = mrb_sym_mul;
+        goto L_SEND_CONSTSYM;
       }
       NEXT;
     }
 
-    CASE(OP_DIV, BB) {
+    CASE(OP_DIV, B) {
 #ifndef MRB_WITHOUT_FLOAT
       double x, y, f;
 #endif
@@ -2411,7 +2424,8 @@ RETRY_TRY_BLOCK:
 #endif
       default:
         c = 1;
-        goto L_SEND;
+        mid = mrb_sym_div;
+        goto L_SEND_CONSTSYM;
       }
 
 #ifndef MRB_WITHOUT_FLOAT
@@ -2428,13 +2442,13 @@ RETRY_TRY_BLOCK:
       NEXT;
     }
 
-    CASE(OP_ADDI, BBB) {
+    CASE(OP_ADDI, BB) {
       /* 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 = (mrb_int)c;
+          mrb_int y = (mrb_int)b;
           mrb_int z;
 
           if (mrb_int_add_overflow(x, y, &z)) {
@@ -2451,22 +2465,23 @@ RETRY_TRY_BLOCK:
 #ifdef MRB_WORD_BOXING
         {
           mrb_float x = mrb_float(regs[a]);
-          SET_FLOAT_VALUE(mrb, regs[a], x + c);
+          SET_FLOAT_VALUE(mrb, regs[a], x + b);
         }
 #else
-        mrb_float(regs[a]) += c;
+        mrb_float(regs[a]) += b;
 #endif
         break;
 #endif
       default:
-        SET_INT_VALUE(regs[a+1], c);
+        SET_INT_VALUE(regs[a+1], b);
         c = 1;
-        goto L_SEND;
+        mid = mrb_sym_add;
+        goto L_SEND_CONSTSYM;
       }
       NEXT;
     }
 
-    CASE(OP_SUBI, BBB) {
+    CASE(OP_SUBI, BB) {
       mrb_value *regs_a = regs + a;
 
       /* need to check if + is overridden */
@@ -2474,7 +2489,7 @@ RETRY_TRY_BLOCK:
       case MRB_TT_FIXNUM:
         {
           mrb_int x = mrb_fixnum(regs_a[0]);
-          mrb_int y = (mrb_int)c;
+          mrb_int y = (mrb_int)b;
           mrb_int z;
 
           if (mrb_int_sub_overflow(x, y, &z)) {
@@ -2491,17 +2506,18 @@ RETRY_TRY_BLOCK:
 #ifdef MRB_WORD_BOXING
         {
           mrb_float x = mrb_float(regs[a]);
-          SET_FLOAT_VALUE(mrb, regs[a], (mrb_float)x - (mrb_float)c);
+          SET_FLOAT_VALUE(mrb, regs[a], (mrb_float)x - (mrb_float)b);
         }
 #else
-        mrb_float(regs_a[0]) -= c;
+        mrb_float(regs_a[0]) -= b;
 #endif
         break;
 #endif
       default:
-        SET_INT_VALUE(regs_a[1], c);
+        SET_INT_VALUE(regs_a[1], b);
         c = 1;
-        goto L_SEND;
+        mid = mrb_sym_sub;
+        goto L_SEND_CONSTSYM;
       }
       NEXT;
     }
@@ -2509,7 +2525,7 @@ RETRY_TRY_BLOCK:
 #define OP_CMP_BODY(op,v1,v2) (v1(regs[a]) op v2(regs[a+1]))
 
 #ifdef MRB_WITHOUT_FLOAT
-#define OP_CMP(op) do {\
+#define OP_CMP(op, sym) do {\
   int result;\
   /* need to check if - is overridden */\
   switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {\
@@ -2518,7 +2534,8 @@ RETRY_TRY_BLOCK:
     break;\
   default:\
     c = 1;\
-    goto L_SEND;\
+    mid = mrb_sym_ ## sym;\
+    goto L_SEND_CONSTSYM;\
   }\
   if (result) {\
     SET_TRUE_VALUE(regs[a]);\
@@ -2528,7 +2545,7 @@ RETRY_TRY_BLOCK:
   }\
 } while(0)
 #else
-#define OP_CMP(op) do {\
+#define OP_CMP(op, sym) do {\
   int result;\
   /* need to check if - is overridden */\
   switch (TYPES2(mrb_type(regs[a]),mrb_type(regs[a+1]))) {\
@@ -2546,7 +2563,8 @@ RETRY_TRY_BLOCK:
     break;\
   default:\
     c = 1;\
-    goto L_SEND;\
+    mid = mrb_sym_ ## sym;\
+    goto L_SEND_CONSTSYM;\
   }\
   if (result) {\
     SET_TRUE_VALUE(regs[a]);\
@@ -2557,33 +2575,33 @@ RETRY_TRY_BLOCK:
 } while(0)
 #endif
 
-    CASE(OP_EQ, BB) {
+    CASE(OP_EQ, B) {
       if (mrb_obj_eq(mrb, regs[a], regs[a+1])) {
         SET_TRUE_VALUE(regs[a]);
       }
       else {
-        OP_CMP(==);
+        OP_CMP(==, eq);
       }
       NEXT;
     }
 
-    CASE(OP_LT, BB) {
-      OP_CMP(<);
+    CASE(OP_LT, B) {
+      OP_CMP(<, lt);
       NEXT;
     }
 
-    CASE(OP_LE, BB) {
-      OP_CMP(<=);
+    CASE(OP_LE, B) {
+      OP_CMP(<=, le);
       NEXT;
     }
 
-    CASE(OP_GT, BB) {
-      OP_CMP(>);
+    CASE(OP_GT, B) {
+      OP_CMP(>, gt);
       NEXT;
     }
 
-    CASE(OP_GE, BB) {
-      OP_CMP(>=);
+    CASE(OP_GE, B) {
+      OP_CMP(>=, ge);
       NEXT;
     }