64-bit in Leopard

[OneSadCookie]

Yes, Carbon and Cocoa are 64-bit in Leopard. Yes, on the Intel chips, 64-bit is a performance advantage.

Three-way universal binary, anyone? How about a six-way one? :)

[Max]

Hum, what about the G5. It is 64-bit too. It's funny though - the previous generation (PowerMac G5) has more advanced technology (64-bit) than the newest generation (Intel iMac which is 32-bit).

[OneSadCookie]

On PowerPC, 64-bit is a performance disadvantage -- the only reason you'd use it is if you actually wanted to use more than 4GB of RAM in one process.

On Intel, 64-bit is a substantial performance advantage, so you'll want to use it whenever possible.

Apple've said that Leopard's 64-bit Carbon and Cocoa apply to both Intel and PowerPC, though.

The three-way UB that'll be "standard" I guess is 32-bit PowerPC + 32-bit Intel + 64-bit Intel, but there might be reason to make a six-way UB (32-bit PowerPC without Altivec, 32-bit PowerPC with Altivec, 32-bit PowerPC with Altivec and sqrt, 64-bit PowerPC with Altivec and sqrt, 32-bit Intel, 64-bit Intel).

[FreakSoftware]

The G5 in the iMac was a joke though. There was no reason to use a G5 other than the fact that it was faster than the G4. 64 bit didn't mean anything there.

[akb825]

Wouldn't 64 bit only benefit you if you're actually using 64 bit integers/floating point numbers? Assuming that's the case, it won't make much of a difference most of the time.

[OneSadCookie]

64-bit Intel chips have twice the number of architected registers that 32-bit ones do. That's where the performance improvement comes from.

[akb825]

Alrighty, thanks. Good move for them, and the perfect opportunity to implement such a change without breaking everything.

[KittyMac]

On Intel, 64-bit is a substantial performance advantage, so you'll want to use it whenever possible.

Actually, this is almost true. Many programs have been profiled already, and MOST benefit from 64-bit (on a varying scale from "some" to "a whole lot"). However, there are a few tried that are negatively impacted by 64-bit.

You won't know for sure until you recompile and run it.

[OneSadCookie]

Interesting post from Ian Ollmann on the subject: http://lists.apple.com/archives/perfoptimization-dev/2006/Aug/msg00006.html

[OneSadCookie]

Interesting post here:
http://www.aeroxp.org/board/index.php?showtopic=5142&hl=
says that APIs that have been deprecated already have *not* been ported to 64-bit. Guess those deprecation warnings may have been more important than some people have been pretending ;)

I'm sure this post breaches NDA, so take a local copy of it before it vanishes ;)

[FreakSoftware]

It seems strange to me what's under NDA and what isn't. I get from Apple's point of view that it makes it simple for them, but I can't imagine them going after some developers because they said "deprecated APIs aren't ported to 64-bit" or "Interface Builder 3.0 is totally rewritten and rocks your socks off"

[PowerMacX]

Well, if you consider that Apple said that they didn't want Microsoft to get a head-start, it makes sense. Well... no it doesn't: Microsoft's MacBU has without a Premium ADC membership, right? ;)

[FreakSoftware]

Exactly. :)

And many of these details aren't exactly... revolutionary. I suppose they do it so they can change it as much as they want and not receive (as much) flak for it.