ops.h: add `OP_SYMBOL` instruction.

It generates a symbol by interning from the pool string.

include/mruby/ops.h

@@ -91,6 +91,7 @@ OPCODE(AREF,       BBB)      /* R(a) = R(b)[c] */
 OPCODE(ASET,       BBB)      /* R(a)[c] = R(b) */
 OPCODE(APOST,      BBB)      /* *R(a),R(a+1)..R(a+c) = R(a)[b..] */
 OPCODE(INTERN,     B)        /* R(a) = intern(R(a)) */
+OPCODE(SYMBOL,     BB)       /* R(a) = intern(Pool(b)) */
 OPCODE(STRING,     BB)       /* R(a) = str_dup(Pool(b)) */
 OPCODE(STRCAT,     B)        /* str_cat(R(a),R(a+1)) */
 OPCODE(HASH,       BB)       /* R(a) = hash_new(R(a),R(a+1)..R(a+b*2-1)) */

mrbgems/mruby-compiler/core/codegen.c

@@ -1757,6 +1757,16 @@ static void
 gen_intern(codegen_scope *s)
 {
   pop();
+  if (!no_peephole(s)) {
+    struct mrb_insn_data data = mrb_last_insn(s);
+
+    if (data.insn == OP_STRING && data.a == cursp()) {
+      rewind_pc(s);
+      genop_2(s, OP_SYMBOL, data.a, data.b);
+      push();
+      return;
+    }
+  }
   genop_1(s, OP_INTERN, cursp());
   push();
 }

src/codedump.c

@@ -455,6 +455,11 @@ codedump(mrb_state *mrb, const mrb_irep *irep)
       printf("OP_INTERN\tR%d", a);
       print_lv_a(mrb, irep, a);
       break;
+    CASE(OP_SYMBOL, BB):
+      mrb_assert((irep->pool[b].tt&IREP_TT_NFLAG)==0);
+      printf("OP_SYMBOL\tR%d\tL(%d)\t; %s", a, b, irep->pool[b].u.str);
+      print_lv_a(mrb, irep, a);
+      break;
     CASE(OP_STRING, BB):
       if ((irep->pool[b].tt & IREP_TT_NFLAG) == 0) {
         printf("OP_STRING\tR%d\tL(%d)\t; %s", a, b, irep->pool[b].u.str);

src/vm.c

@@ -2630,7 +2630,22 @@ RETRY_TRY_BLOCK:
       mrb_sym sym = mrb_intern_str(mrb, regs[a]);
 
       regs[a] = mrb_symbol_value(sym);
-      mrb_gc_arena_restore(mrb, ai);
+      NEXT;
+    }
+
+    CASE(OP_SYMBOL, BB) {
+      size_t len;
+      mrb_sym sym;
+
+      mrb_assert((pool[b].tt&IREP_TT_NFLAG)==0);
+      len = pool[b].tt >> 2;
+      if (pool[b].tt & IREP_TT_SFLAG) {
+        sym = mrb_intern_static(mrb, pool[b].u.str, len);
+      }
+      else {
+        sym  = mrb_intern(mrb, pool[b].u.str, len);
+      }
+      regs[a] = mrb_symbol_value(sym);
       NEXT;
     }