[FFmpeg-devel] [PATCH] Altivec split-radix FFT

[Loren Merritt]

On Wed, 26 Aug 2009, M?ns Rullg?rd wrote:

>> +        "mtctr %0 \n"
>> +        "stw 2,-4(1) \n"
>> +        "li 2,16 \n"
>> +        "bctrl \n"
>> +        "lwz 2,-4(1) \n" // ABI docs say r2 is general purpose and
>> caller-saved, but gcc doesn't save it and crashes
>
> I assume you meant stwu to push the value of r2 and lwz/addi to restore
> it.  Even with that change, it would fail on ppc64 since you'd be
> preserving only half the register.  Furthermore, the ABI mandates a
> 16-byte-aligned stack at all times, but you could probably get away
> without that if you never call any compiled code.

I meant to store it in the redzone. My asm also never touches the stack 
pointer, and store their return addresses at fixed locations in the 
redzone.

--Loren Merritt