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Mail Archives: djgpp-workers/1999/04/28/13:46:14

Message-Id: <m10cYLV-000S8OC@inti.gov.ar>
Comments: Authenticated sender is <salvador AT natacha DOT inti DOT gov DOT ar>
From: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
Organization: INTI
To: DJ Delorie <dj AT delorie DOT com>, djgpp-workers AT delorie DOT com
Date: Wed, 28 Apr 1999 11:16:33 +0000
MIME-Version: 1.0
Subject: Re: [dma AT hpesdma DOT fc DOT hp DOT com: Performance Observation]
In-reply-to: <199904281552.LAA00704@envy.delorie.com>
References: <199904281342 DOT OAA12455 AT melchard DOT ee DOT ucl DOT ac DOT uk> (cmatraki AT ee DOT ucl DOT ac DOT uk)
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DJ Delorie <dj AT delorie DOT com> wrote:
 
> > I'm not sure whether 32-byte alignment is the best option, but the waste
> 
> 8-byte alignment is my vote.  Note that a global alignment is wrong,
> because ctor/dtor tables will get corrupted if they're padded.
> 
> > Another related question is, what is the guaranteed alignment from malloc?
> 
> malloc returns pointers that are guaranteed to be sufficiently aligned
> for any use.  Of course, on the ix86, any alignment is "sufficient".
> However, djgpp's current malloc aligns to 8-byte boundaries.

I vote for 16 bytes. Why? 128 bits data path is 16 bytes and some seconds ago 
I taked a look into a Win32 program (almost sure is a VC++ one) and I saw 
upto 14 NOPs, so it looks like 16 bytes is what they use for code. 
Of course you can see the bloat in the code, it is full of NOPs. Also: NOP is 
not the only one used, but is very easy to see with an Hexa editor.

SET
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Salvador Eduardo Tropea (SET). (Electronics Engineer)
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