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

Måns Rullgård mans
Thu Aug 27 21:31:12 CEST 2009

Loren Merritt <lorenm at u.washington.edu> writes:

> 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.

What redzone?  There isn't one on PPC.

M?ns Rullg?rd
mans at mansr.com

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