Fix PR43404, PR48470, PR64744 ICE on naked functions

[Jeff Law]

On 06/03/2015 02:15 PM, Alexander Basov wrote:
> Hello Jeff,
> please find updated patch attached
>
>>> diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
>>> index b190f91..c6db8a9 100644
>>> --- a/gcc/cfgexpand.c
>>> +++ b/gcc/cfgexpand.c
>>> @@ -1382,7 +1382,15 @@ expand_one_var (tree var, bool toplevel, bool
>>> really_expand)
>>>      else
>>>        {
>>>          if (really_expand)
>>> -        expand_one_stack_var (origvar);
>>> +        {
>>> +          if (!targetm.calls.allocate_stack_slots_for_args ())
>>> +            error ("cannot allocate stack for variable %q+D, naked
>>> function.",
>>> +                   var);
>>> +
>>> +          expand_one_stack_var (origvar);
>>> +        }
>> So how do you know ORIGVAR is an argument here before issuing the
>> error?  ie, shouldn't you verify that the underlying object is a
>> PARM_DECL? If there's some way we already know we're dealing with a
>> PARM_DECL, then just say so.
> In case of naked function stack should not be used not only for function
> args, but also for any local variables.
> So, i think we don't need to check if underlying object is a PARM_DECL.
Then that would indicate that we're using the wrong test 
(allocate_stack_slot_for_args).  That hook is for whether or not 
arguments should have stack slots allocated.  Yet you're issuing an 
error for more than just PARM_DECLs.

Shouldn't you instead be checking if the current function is a naked 
function or not by checking the attributes of the current function?

Jeff