Re: Xamiga segfaults with 16 bit on CV64

[David Laight <david%l8s.co.uk@localhost>]

On Sun, Jan 06, 2008 at 02:43:00PM +0100, Frank Wille wrote:
> 
> Disassembly of the crash location:
> [...]
> 0x91bd4 <cfb16FillBoxTile32sCopy+56>:   moveal %a1@(16),%a0
> 0x91bd8 <cfb16FillBoxTile32sCopy+60>:   movel %a1,%sp@-
> 0x91bda <cfb16FillBoxTile32sCopy+62>:   moveal %a0@(372),%a0
> 0x91bde <cfb16FillBoxTile32sCopy+66>:   jsr %a0@
> 0x91be0 <cfb16FillBoxTile32sCopy+68>:   addql #4,%sp
> 0x91be2 <cfb16FillBoxTile32sCopy+70>:   movel %a0@(32),%fp@(-24)  <-- HERE
> [...]
> 
> The code looks to me like a compiler bug (unless the sub-routine is meant to
> return a result in a0). Register a0 is reused for deferencing after a sub-
> routine call, although it is definitely a volatile register (and zero after
> returning from the sub-routine).

%a0 is used to return a pointer from a function.
So it looks as though the called function returned 'NULL' and it wasn't
checked for.

        David

-- 
David Laight: david%l8s.co.uk@localhost