Where is setup for "goto" in nested function created?

Where is setup for "goto" in nested function created?

[hutchinsonandy]

During  the process of fixing setjmp for AVR target, I needed to define 
targetm.builtin_setjmp_frame_value () to be used in
expand_builtin_setjmp_setup().

This sets the value of the Frame pointer stored in jump buffer.

I set this "value" to virtual_stack_vars_rtx+1 (==frame_pointer)
Receiver defined in target latter restores frame pointer using 
virtual_stack_vars_rtx = value - 1

This produce correct code as expected and avoids run-time add/sub of 
offsets. (setjmp works!)

However, for a normal goto   used inside a nested function, a different 
part of gcc creates the code to store frame pointer  (not 
expand_builtin_setjmp_setup).   I can't find this code.

The issue I have is that this "goto_setup" code does NOT use 
targetm.builtin_setjmp_frame_value - but seems to use 
value=virtual_stack_vars_rtx, which is incompatible with my target 
receiver.

So where is the goto setup code created? And is there a bug here?

regards
Andy

Re: Where is setup for "goto" in nested function created?

[David Daney]

hutchinsonandy@aim.com wrote:
> During  the process of fixing setjmp for AVR target, I needed to define 
> targetm.builtin_setjmp_frame_value () to be used in
> expand_builtin_setjmp_setup().
> 
> This sets the value of the Frame pointer stored in jump buffer.
> 
> I set this "value" to virtual_stack_vars_rtx+1 (==frame_pointer)
> Receiver defined in target latter restores frame pointer using 
> virtual_stack_vars_rtx = value - 1
> 
> This produce correct code as expected and avoids run-time add/sub of 
> offsets. (setjmp works!)
> 
> However, for a normal goto   used inside a nested function, a different 
> part of gcc creates the code to store frame pointer  (not 
> expand_builtin_setjmp_setup).   I can't find this code.
> 
> The issue I have is that this "goto_setup" code does NOT use 
> targetm.builtin_setjmp_frame_value - but seems to use 
> value=virtual_stack_vars_rtx, which is incompatible with my target 
> receiver.
> 
> So where is the goto setup code created? And is there a bug here?
> 

Perhaps you need to implement one or more of: save_stack_nonlocal, 
restore_stack_nonlocal, nonlocal_goto, and/or nonlocal_goto_receiver.

David Daney

Re: Where is setup for "goto" in nested function created?

[hutchinsonandy]

I already have nonlocal_goto, and  nonlocal_goto_receiver.

These expect saved frame pointer to be virtual_stack_vars_rtx+1.

For setjmp the value is determined by 
targetm.builtin_setjmp_frame_value - which I defined and is correct.

But for goto the value is created by some other code - which appears to 
be wrong but I can't find!




-----Original Message-----
From: David Daney <ddaney@avtrex.com>
To: hutchinsonandy@aim.com
Cc: gcc@gcc.gnu.org
Sent: Thu, 22 May 2008 1:16 pm
Subject: Re: Where is setup for "goto" in nested function created?


hutchinsonandy@aim.com wrote: 
> During the process of fixing setjmp for AVR target, I needed to 
define > targetm.builtin_setjmp_frame_value () to be used in 
> expand_builtin_setjmp_setup(). 
> > This sets the value of the Frame pointer stored in jump buffer. 
> > I set this "value" to virtual_stack_vars_rtx+1 (==frame_pointer) 
> Receiver defined in target latter restores frame pointer using > 
virtual_stack_vars_rtx = value - 1 
> > This produce correct code as expected and avoids run-time add/sub 
of > offsets. (setjmp works!) 
> > However, for a normal goto used inside a nested function, a 
different > part of gcc creates the code to store frame pointer (not > 
expand_builtin_setjmp_setup). I can't find this code. 
> > The issue I have is that this "goto_setup" code does NOT use > 
targetm.builtin_setjmp_frame_value - but seems to use > 
value=virtual_stack_vars_rtx, which is incompatible with my target > 
receiver. 
> > So where is the goto setup code created? And is there a bug here? 
>  
Perhaps you need to implement one or more of: save_stack_nonlocal, 
restore_stack_nonlocal, nonlocal_goto, and/or nonlocal_goto_receiver. 
 
David Daney 

Re: Where is setup for "goto" in nested function created?

[Ian Lance Taylor]

hutchinsonandy@aim.com writes:

> However, for a normal goto   used inside a nested function, a
> different part of gcc creates the code to store frame pointer  (not
> expand_builtin_setjmp_setup).   I can't find this code.

I think you are looking for expand_builtin_nonlocal_goto in
builtins.c.

Ian

Re: Where is setup for "goto" in nested function created?

[hutchinsonandy]

I think my last email crossed your reply - so apolgies for restating:

expand_builtin_nonlocal_goto is fine. This perform stack restore, 
extracts frame pointer value and does jump.

reciever is fine - this jump destination does restore of frame pointer.

The problem I have is with frame pointer value that is saved in by 
"setup" prior to all this

For goto is does not use expand_builtin_setjmp_setup - (pathetically) I 
can't find what it is using.

Andy



-----Original Message-----
From: Ian Lance Taylor <iant@google.com>
To: hutchinsonandy@aim.com
Cc: gcc@gcc.gnu.org
Sent: Thu, 22 May 2008 2:26 pm
Subject: Re: Where is setup for "goto" in nested function created?



hutchinsonandy@aim.com writes:

> However, for a normal goto   used inside a nested function, a
> different part of gcc creates the code to store frame pointer  (not
> expand_builtin_setjmp_setup).   I can't find this code.

I think you are looking for expand_builtin_nonlocal_goto in
builtins.c.

Ian

Re: Where is setup for "goto" in nested function created?

[Ian Lance Taylor]

hutchinsonandy@aim.com writes:

> expand_builtin_nonlocal_goto is fine. This perform stack restore,
> extracts frame pointer value and does jump.
>
> reciever is fine - this jump destination does restore of frame pointer.
>
> The problem I have is with frame pointer value that is saved in by
> "setup" prior to all this
>
> For goto is does not use expand_builtin_setjmp_setup - (pathetically)
> I can't find what it is using.

I'm not really sure just what you are after (and I'm not sure that I
would know the answer if I did).  Most of the relevant code should be
somewhere in tree-nested.c.  Also look at expand_function_start, and
in general any use of cfun->nonlocal_goto_save_area.

Ian

Re: Where is setup for "goto" in nested function created?

[Andy H]

Thanks Ian!

I found it in function.c (expand_function_start)

      emit_move_insn (r_save, virtual_stack_vars_rtx);

Whereas it should be

      emit_move_insn (r_save, targetm.builtin_setjmp_frame_value ());

to match same construction used for setjmp.

thanks for help!



Ian Lance Taylor wrote:
> hutchinsonandy@aim.com writes:
>
>   
>> expand_builtin_nonlocal_goto is fine. This perform stack restore,
>> extracts frame pointer value and does jump.
>>
>> reciever is fine - this jump destination does restore of frame pointer.
>>
>> The problem I have is with frame pointer value that is saved in by
>> "setup" prior to all this
>>
>> For goto is does not use expand_builtin_setjmp_setup - (pathetically)
>> I can't find what it is using.
>>     
>
> I'm not really sure just what you are after (and I'm not sure that I
> would know the answer if I did).  Most of the relevant code should be
> somewhere in tree-nested.c.  Also look at expand_function_start, and
> in general any use of cfun->nonlocal_goto_save_area.
>
> Ian
>