Preallocate SystemStackError; ref #3421

include/mruby.h

@@ -221,6 +221,7 @@ typedef struct mrb_state {
   struct RClass *eException_class;
   struct RClass *eStandardError_class;
   struct RObject *nomem_err;              /* pre-allocated NoMemoryError */
+  struct RObject *stack_err;              /* pre-allocated SysStackError */
 #ifdef MRB_GC_FIXED_ARENA
   struct RObject *arena_err;              /* pre-allocated arena overfow error */
 #endif
@@ -1110,7 +1111,6 @@ MRB_API void mrb_print_error(mrb_state *mrb);
 #define E_SYNTAX_ERROR              (mrb_exc_get(mrb, "SyntaxError"))
 #define E_LOCALJUMP_ERROR           (mrb_exc_get(mrb, "LocalJumpError"))
 #define E_REGEXP_ERROR              (mrb_exc_get(mrb, "RegexpError"))
-#define E_SYSSTACK_ERROR            (mrb_exc_get(mrb, "SystemStackError"))
 
 #define E_NOTIMP_ERROR              (mrb_exc_get(mrb, "NotImplementedError"))
 #define E_FLOATDOMAIN_ERROR         (mrb_exc_get(mrb, "FloatDomainError"))

src/backtrace.c

@@ -263,7 +263,7 @@ mrb_print_backtrace(mrb_state *mrb)
 {
   mrb_value backtrace;
 
-  if (!mrb->exc || mrb_obj_is_kind_of(mrb, mrb_obj_value(mrb->exc), E_SYSSTACK_ERROR)) {
+  if (!mrb->exc) {
     return;
   }
 

src/error.c

@@ -532,7 +532,7 @@ mrb_no_method_error(mrb_state *mrb, mrb_sym id, mrb_value args, char const* fmt,
 void
 mrb_init_exception(mrb_state *mrb)
 {
-  struct RClass *exception, *runtime_error, *script_error;
+  struct RClass *exception, *runtime_error, *script_error, *stack_error;
 
   mrb->eException_class = exception = mrb_define_class(mrb, "Exception", mrb->object_class); /* 15.2.22 */
   MRB_SET_INSTANCE_TT(exception, MRB_TT_EXCEPTION);
@@ -553,5 +553,6 @@ mrb_init_exception(mrb_state *mrb)
 #endif
   script_error = mrb_define_class(mrb, "ScriptError", mrb->eException_class);                /* 15.2.37 */
   mrb_define_class(mrb, "SyntaxError", script_error);                                        /* 15.2.38 */
-  mrb_define_class(mrb, "SystemStackError", exception);
+  stack_error = mrb_define_class(mrb, "SystemStackError", exception);
+  mrb->stack_err = mrb_obj_ptr(mrb_exc_new_str_lit(mrb, stack_error, "stack level too deep"));
 }

src/gc.c

@@ -865,6 +865,7 @@ root_scan_phase(mrb_state *mrb, mrb_gc *gc)
   }
   /* mark pre-allocated exception */
   mrb_gc_mark(mrb, (struct RBasic*)mrb->nomem_err);
+  mrb_gc_mark(mrb, (struct RBasic*)mrb->stack_err);
 #ifdef MRB_GC_FIXED_ARENA
   mrb_gc_mark(mrb, (struct RBasic*)mrb->arena_err);
 #endif

src/vm.c

@@ -162,7 +162,7 @@ stack_extend_alloc(mrb_state *mrb, int room, int keep)
      to prevent infinite recursion. However, do this only after resizing the stack, so mrb_raise has stack space to work with. */
   if (size > MRB_STACK_MAX) {
     init_new_stack_space(mrb, room, keep);
-    mrb_raise(mrb, E_SYSSTACK_ERROR, "stack level too deep. (limit=" MRB_STRINGIZE(MRB_STACK_MAX) ")");
+    mrb_exc_raise(mrb, mrb_obj_value(mrb->stack_err));
   }
 }