Re: [avr-gcc-list] Add builtins in avr target.

[Andy H]

As before I disagree.

But let Eric and users decide:

1) Should __builtin_return_address()  be disable for 256K device. Since 
it will only return word not 3 bytes.
2) Should function pointer arithmetic be disabled for 256K device - 
since it will only operate on word address.

I think answer should be no. But there should be documented restrictions.

Andy

Anatoly Sokolov wrote:
> Hi.
>
>   
> > __builtin_return_address is extremely useful for target error reporting. 
> > e.g. a function can be called(or trapped)  to report error in another 
> > part of program. This allows such routines to determine the address of 
> > the caller without using naked asm functions.
> >
> > You are correct, that return address will only give 16bit pointer. But 
> > that covers most uses.
> >
> > It would seem easier to implement than create documents and disable all 
> > current and future testcases that use it. That would seem to be 
> > confirmed by the fact that  bug reports  have been outstanding since 2005.
> >
> > Of course, Eric and other AVR users may disagree.
> >
> >     
>
> Word or byte address return  "__builtin_return_address"? 
> I consider that, it will be better that it returned the word address.
>
> For those architectures where it cannot return the correct address, the  
> "__builtin_return_address" should be disabled.
>
> +static void avr_init_builtins (void);
>
> +#undef TARGET_INIT_BUILTINS
> +#define TARGET_INIT_BUILTINS avr_init_builtins
>
>
> +void
> +avr_init_builtins  (void)
> +{
> +  if (AVR_HAVE_EIJMP_EICALL)  // if "__builtin_return_address" return word 
> address.
> +    {
> +      disable_builtin_function ("return_address");
> +    }
> +}
>
>
> Anatoly.
>   
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