Re: GCC EH unwinding bug and libjava calling std::terminate ()

[Jan Hubicka <hubicka@ucw.cz>]

> Jan Hubicka wrote:
> 
> > current mainline is buggy in EH unwinding effectivly ignoring
> > MUST_NOT_THROW regions when reached via RESX from local handlers.
> > See http://gcc.gnu.org/ml/gcc-patches/2009-03/msg01285.html for details.
> > 
> > Unfortunately this patch causes bootstrap failure when building libjava,
> > because std::terminate() is now called.  The call comes from
> > run_proxy in natVMProxy.cc where we have cleanup code calling
> > destructor of:
> > 
> > _Jv_InterpFrame frame_desc (self->self, thread, proxyClass,
> >                               NULL, frame_proxy);
> > 
> > Now the desctuctor is pretty simple but because of:
> > 'if a destructor called during stack unwinding exits with an exception,
> > std::terminate is called'
> > 
> > and because we use -fnon-call-excpetion and destructor is accessing
> > memory, we keep MUST_NOT_THROW terminate () call accessible
> > because after inlining the destructor, cleanup might unwind up
> > to that MUST_NOT_THROW.
> > 
> > Questio is how to fix this situation? Shall we link with C++ runtime,
> 
> Please don't.
> 
> > or use -fno-non-call-exceptions
> 
> No, because it might segfault, and we need to catch it.
> 
> > to build this file or somehow restruture
> > code to avoid this case?
> 
> /* Gimplify a MUST_NOT_THROW_EXPR.  */
> 
> static enum gimplify_status
> gimplify_must_not_throw_expr (tree *expr_p, gimple_seq *pre_p)
> {
>   tree stmt = *expr_p;
>   tree temp = voidify_wrapper_expr (stmt, NULL);
>   tree body = TREE_OPERAND (stmt, 0);
>   tree termination;
> 
>   if (pragma_java_exceptions)
>     termination = terminate_node;
>   else
>     termination = abort_node;

OK, pragma_java_exceptions variable is not there, does something like
this work for you?

I would like to commit this to mainline so the MUST_NOT_THROW fix can go
as well.  I am commiting it to pretty-ipa in meantime.

Honza

Index: cp/except.c
===================================================================
*** cp/except.c	(revision 145101)
--- cp/except.c	(working copy)
*************** choose_personality_routine (enum languag
*** 353,358 ****
--- 353,359 ----
  
      case lang_java:
        state = chose_java;
+       terminate_node = built_in_decls [BUILT_IN_ABORT];
        eh_personality_libfunc = init_one_libfunc (USING_SJLJ_EXCEPTIONS
  						 ? "__gcj_personality_sj0"
  						 : "__gcj_personality_v0");