Merge pull request #6191 from leviongit/sym-eql

Speed up symbol equality comparison

src/symbol.c

@@ -691,4 +691,5 @@ mrb_init_symbol(mrb_state *mrb)
   mrb_define_method_id(mrb, sym, MRB_SYM(to_sym),  mrb_obj_itself,  MRB_ARGS_NONE());      /* 15.2.11.3.4 */
   mrb_define_method_id(mrb, sym, MRB_SYM(inspect), sym_inspect, MRB_ARGS_NONE());          /* 15.2.11.3.5(x) */
   mrb_define_method_id(mrb, sym, MRB_OPSYM(cmp),   sym_cmp,     MRB_ARGS_REQ(1));
+  mrb_define_method_id(mrb, sym, MRB_OPSYM(eq),    mrb_obj_equal_m,      MRB_ARGS_REQ(1));
 }

src/vm.c

@@ -2660,6 +2660,9 @@ RETRY_TRY_BLOCK:
       if (mrb_obj_eq(mrb, regs[a], regs[a+1])) {
         SET_TRUE_VALUE(regs[a]);
       }
+      else if (mrb_symbol_p(regs[a])) {
+        SET_FALSE_VALUE(regs[a]);
+      }
       else {
         OP_CMP(==,eq);
       }