[FFmpeg-devel] [FFmpeg-cvslog] r12171 - trunk/doc/optimization.txt

Michael Niedermayer michaelni
Thu Feb 21 21:07:58 CET 2008

On Thu, Feb 21, 2008 at 09:57:23PM +0200, Uoti Urpala wrote:
> On Thu, 2008-02-21 at 20:11 +0100, Michael Niedermayer wrote:
> > As you can see gcc injects 2 unneeded lea instructions in the innermost loop.
> It'd need at least one other instruction instead though. Anyway I do not
> see that behavior with Debian's gcc-4.3, gcc always uses 3 instructions
> for the adds (same as the handwritten asm).

The asm output is from the person who "suggested" the change, IIRC he claimed
it was gcc 4.3

Anyway this code can be changed so it needs just 2 add and 0 lea. Though this
needs a change in the asm() and we can thus not blame gcc for that ...

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Thouse who are best at talking, realize last or never when they are wrong.
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