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Re: optimizing compilers
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Re: optimizing compilers


  • Subject: Re: optimizing compilers
  • From: John Hörnkvist <email@hidden>
  • Date: Fri, 1 Feb 2002 23:07:10 +0100

On Friday, February 1, 2002, at 08:34 PM, Finlay Dobbie wrote:

No, it's a combination of multiple factors. It's well known that gcc 2.95.2 sucks for PPC code generation.

As far as I know, gcc sucks for code generation, period. You can help it a fair bit by using some of the attributes and language extensions that it implements.

I think it should be better with gcc 3.1, which Stan Shebs and the Apple compiler team are working overtime on bringing up to scratch on Darwin/OS X.

I've benchmarked a fairly recent version of gcc 3.1 and 2.95.2, and the difference has been quite small.

To make matters worse, the PPC seems rather sensitive to bad code; when I turn on optimizations in my research compiler, I can speed up execution by almost a factor of three on the PPC (16.11 to 5.76 seconds) but less than two times on an AMD Duron (7.95 to 4.32 seconds).

I heard a while back that they moved a lot of their ex-MrC engineers over to work on gcc 3.1/Darwin (MrC was Apple's compiler that was part of MPW, and it was widely recognised as being one of the most optimizing PPC compilers. see http://developer.apple.com/tools/mpw-
tools/compilers/benchmarks/index.html for examples).

Well, that makes sense; no reason to have them working on a dead compiler.

Regards,
John Hornkvist
--
ToastedMarshmallow, the perfect Cocoa companion
http://www.toastedmarshmallow.com


References: 
 >Re: optimizing compilers (From: Finlay Dobbie <email@hidden>)

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