Re: Universal Builds
Re: Universal Builds
- Subject: Re: Universal Builds
- From: Wade Tregaskis <email@hidden>
- Date: Wed, 03 Aug 2011 23:19:34 -0700
I have these build settings:
Architectures : Standard(32/64-bit Universal)
Valid Architectures: ppc ppc64 ppc970 ppc7400 i386 x86_64
Valid Architectures is more like a mask... it's listing the things that you could build for. The actual Architectures setting may specify a subset of this to actually build at the current time.
tl;dr: Xcode's default, {ppc, i386, x86_64}, are the only three you are likely to care about. Even 'ppc' is probably unnecessary these days.
Anything built for 'ppc' will work on all the other forms of ppc, being the lowest common denominator. 'ppc970' and 'ppc7400' just specify that the compiler can use special instructions (e.g. AltiVec) and also that it should order instructions [relatively] optimally for those architectures. That's particularly important for the PPC970 (G5) in order to achieve good performance. [[ It's also why Xcode defaults to scheduling for the G5 even if you target generic 'ppc'... can't have those G4s outperforming G5s now.. ;) ]]
'ppc64' is kind of an odd case... there's very few scenarios in which it's actually useful, since pervasive 64-bit support (in system libraries etc) didn't really come in until Intel. There were also some nasty practical issues with using it, I seem to remember, though the details escape me for the moment. |
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