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

[Anatoly Sokolov]

Hi.

My patch adds avr specific builtins, and has no attitude to GCC standard 
builtins.

> See GCC bug #21080:
> <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21080>
>
> Andy Hutchinson wrote a patch (attached to bug report) to fix this bug
> which adds support for __builtin_return_address.

 As far as I can tell, __builtin_return_address is used entirely for
tracing, profiling, and error reporting. And practically it is not useful for 
AVR 
target. More, this function returns the pointer which is 16-bits on AVR 
target, hence its value for devices with more than 64KB FLASH will be incorrect.

The only practical advantage of this patch to remove 2-3 FALL in GCC testsuite. 
To make truly a working '__builtin_return_address' now it is not possible.

Easier to document '__builtin_return_address' as not supported feature and 
disable 
this testcases in GGG testsuite. And to not complicate AVR backend.

Anatoly.