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Mail Archives: djgpp/2006/04/05/22:30:34

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From: Brian Inglis <Brian DOT Inglis AT SystematicSW DOT Invalid>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Sequence points, any?
Organization: Systematic Software
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Date: Thu, 06 Apr 2006 02:25:41 GMT
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On 5 Apr 2006 17:40:45 -0700 in comp.os.msdos.djgpp, "Bob W"
<dontsend AT operamail DOT com> wrote:

>Thank you very much for your post. That was
>pretty good analysis, which was also good
>enough to remove my remaining doubts about
>the new way gcc is handling the kind of code
>mentioned in this thread.
>
>
>> > If gcc's out-of-sequence optimisation is prevented
>> > by using one of the methods mentioned previously,
>> > the program actually executes a touch faster.
>>
>> ... on the CPU you tried it on.  Which may not be the one it was
>> optimizing for.
>
>I presume that you are not referring to specific
>submodel targets here (e.g. P3, P4, etc.). You
>probably have meant to tell me that gcc's general
>compile method gets tuned torwards hyperthreading
>capable targets - and gcc sticks to its new way of
>handling things regardless whether a "vintage target"
>like the P3 is specified in the command line option
>or not.
>
>Did I get this right?

The model specific optimizations will control what types (if any) of
scheduling are performed and instructions generated. 
Problems with rearranging calls like this may just be bugs due to
recent changes (or fixes for other problems) in the compiler
internals. 

-- 
Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada

Brian DOT Inglis AT CSi DOT com 	(Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca)
    fake address		use address above to reply

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