From:	mert0407 AT sable DOT ox DOT ac DOT uk (George Foot)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Using Pointers ?
Date:	Tue, 04 Feb 1997 06:02:21 GMT
Organization:	Oxford University
Lines:	26
Message-ID:	<32f6cfe0.53398230@news.ox.ac.uk>
References:	<32F662F9 DOT 1F3B AT post DOT comstar DOT ru> <32F66FB9 DOT 1FC2 AT cs DOT com> <32F67138 DOT D72 AT cs DOT com>
NNTP-Posting-Host:	mc31.merton.ox.ac.uk
To:	djgpp AT delorie DOT com
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On Mon, 03 Feb 1997 15:14:00 -0800, "John M. Aldrich"
<fighteer AT cs DOT com> wrote:

>John M. Aldrich wrote:
>> 
>> >  ptr->fld1=fld1;
>> >  ptr->fld2=fld2
>
>Gods... I replied too soon again.  Today is obviously not my day for
>alertness.  :)  When you add these lines, the third function is likely
>to be marginally faster.  It will be even better if you declare 'fld1'
>and 'fld2' as 'register' variables.

Is this true? I was under the impression that gcc's god-like
optimisation would generally make better choices than the average
coder for register variables, i.e. it would figure out that these
ought to be registers without being told for itself. Just a rumour,
though...

...which brings up another point: won't the first two functions also
compile to this? i.e. won't gcc either (a) remember the memory
locations it's using or (b) temporarily registerise them without being
told?

George Foot

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