Re: XCode/MMX: no automatic EMMS instruction
Re: XCode/MMX: no automatic EMMS instruction
- Subject: Re: XCode/MMX: no automatic EMMS instruction
- From: "Sean McBride" <email@hidden>
- Date: Thu, 17 Aug 2006 21:25:07 -0400
Eric Albert (email@hidden) on 2006-08-16 01:00 said:
>The cost of that single emms instruction is why GCC doesn't emit it
>automatically for you. If GCC's own codegen results in MMX
>instructions (which is very rare), it'll emit an emms. But if you
>use MMX instructions in your assembly code, there's a reasonable
>chance you might be trying to use MMX in the function you're
>returning to too, and if we were to emit an emms at the end of your
>current function you'd burn 50 cycles for something you didn't want.
>
>On the other hand, if Visual Studio also automatically emits an emms
>in this case I'd suggest filing a bug at bugreport.apple.com to
>request that GCC do this.
Mark, you might want to try intel's icc also, and see what it does, on
Mac and Windows even.
--
"I object to violence because when it appears to do good, the good is
only temporary; the evil it does is permanent." - Gandhi
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