[FFmpeg-cvslog] r24926 - trunk/libavcodec/x86/vp56dsp.asm

Loren Merritt lorenm
Thu Aug 26 23:08:09 CEST 2010

On Thu, 26 Aug 2010, M?ns Rullg?rd wrote:
> Loren Merritt <lorenm at u.washington.edu> writes:
>> On Thu, 26 Aug 2010, M?ns Rullg?rd wrote:
>>> That problem is also specific to x86.  I know of no other architecture
>>> where the declared type of the counter would make a difference in a
>>> construct like that.
>> Just to be clear: You're saying that there are no archs other than x86
>> where int is 32bit and pointer is 64bit?
> No, and stop being obtuse.  I'm saying that all other 64-bit archs I
> know of simply sign-extend 32-bit values when they are loaded from
> memory, if their type is signed, and operate on the full 64-bit
> registers. In some cases a 32-bit result of an instruction is
> automatically sign-extended when placed in a 64-bit register.  In
> either case, the declared type of an array index has no effect on the
> generated code beyond what is implied by the integer promotion rules
> of C.

Ah, it's the automatic sign-extended of all 32bit ops that I didn't 
guess from your statement. I agree that's more sane than x86.

--Loren Merritt

More information about the ffmpeg-cvslog mailing list