Re: [Tinycc-devel] [PATCH] arm: Handle __builtin_frame_address(1) correctly

[Thomas Preud'homme]

Le samedi 5 janvier 2013 16:35:44, vous avez écrit :
> > 
> > Are you sure the code you compiled for ARM doesn't contain
> > __builtin_return_address instead of __builtin_frame_address?
> 
> Thomas, thanks for correcting my arm assembly errors. I agree I did make
> mistakes, but I'm sure __builtin_frame_address() is used, not
> __builtin_return_address(), and that __builtin_frame_address(1) is wrong.
> Here it is once again:
> 
>     $ cat fp.c
>     #include <stdio.h>
> 
>     void *func(int x)
>     {
>         char *fp1 = __builtin_frame_address(1);
> 
>         printf("Hello World! %i\n", x);
> 
>         fp1 += x;
>         return fp1;
>     }
> 
>     int main()
>     {
>         void *fp0 = __builtin_frame_address(0);
>         void *fp1 = func(0);
> 
>         printf("fp0: %p  fp1: %p\n", fp0, fp1);
>         return 0;
>     }
> 
>     $ arm-linux-gnueabi-gcc-4.4 -ofpapcs -marm -mapcs -mno-sched-prolog -O2
> fp.c
> 
>     $ qemu-arm -L /usr/arm-linux-gnueabi ./fpapcs
>     Hello World! 0
>     fp0: 0x4080010c  fp1: 0x83e0

Yeah sorry, I shouldn't have written this since it fails also for me. I just 
can't believe there is something wrong with gcc and find it much more likely 
that I didn't understand something.

> Kirill

Thomas