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Re: xcode 1.2, -fast and ppc_intrinsics.h
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Re: xcode 1.2, -fast and ppc_intrinsics.h


  • Subject: Re: xcode 1.2, -fast and ppc_intrinsics.h
  • From: Mark Eissler <email@hidden>
  • Date: Thu, 29 Apr 2004 10:12:30 -0400

On Apr 28, 2004, at 8:26 PM, Glen Low wrote:


The C89/C99 and C++98 aliasing rules state that you shall not access an object of type X through an lvalue (e.g. pointer, reference) of type Y, where X and Y are unrelated. Perhaps this is interacting badly with ObjC. (In C++, X and Y can be related through inheritance, but in C there's no such thing so I don't know how it falls out in ObjC).

Yes. I think the problem is ObjC as I'm not recasting.


In practice the aliasing rules really only optimize tight, inlined loops, so you should be quite safe leaving it off ObjC code. You might try -fno-strict-aliasing in addition to -fast to do this (caveat -- haven't tried this myself).

I haven't tried it either but I don't think you can do that. Since -fast turns on the strict aliasing flag, it will probably override -fno-strict-aliasing. At least, this is what it will do with the optimization flag (-fast turns on -O3, if you specify anything else it will be overridden).



The warning itself is likely only a warning rather than a hard error -- you could try googling for it to see what the gcc folk say.

You are absolutely correct, it is a warning only. I just hate to see warnings. Especially when there's a billion of them. What's interesting is that the number of warnings per source file seems to be somehow correlated to the number of methods defined within the file. It's not a 1:1 relationship though. It's more like 3:1.


But something is stopping my build from continuing when I have -fast turned on. Possibly because I have Xcode configured to barf after errors (Continue after errors is turned off).

-mark

--
Mark Eissler, email@hidden
Mixtur Interactive, Inc.
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  • Follow-Ups:
    • Re: xcode 1.2, -fast and ppc_intrinsics.h
      • From: Glen Low <email@hidden>
References: 
 >xcode 1.2, -fast and ppc_intrinsics.h (From: Brian Barnes <email@hidden>)
 >Re: xcode 1.2, -fast and ppc_intrinsics.h (From: Mark Eissler <email@hidden>)
 >Re: xcode 1.2, -fast and ppc_intrinsics.h (From: "email@hidden" <email@hidden>)
 >Re: xcode 1.2, -fast and ppc_intrinsics.h (From: Mark Eissler <email@hidden>)
 >Re: xcode 1.2, -fast and ppc_intrinsics.h (From: Glen Low <email@hidden>)

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