From - Mon Oct 13 08:54:35 1997
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From: Fred Kleinsorge <kleinsorge@star.enet.dec_nospam.com>
Newsgroups: comp.os.vms
Subject: Re: Difference between AlphaVMS & OpenVMS
Date: Mon, 06 Oct 1997 12:56:21 -0400
Organization: OpenVMS Engineering
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Message-ID: <3438DFF5.6A598DCA@star.enet.dec_nospam.com>
References: <35480087@MVB.SAIC.COM> <1997Oct3.181154.1@sldb4.slac.stanford.edu>
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For all those folks out there using SDL from the Freeware CD,
  especially those using C, here is a little known trick...

  On your structure definitions, append the keyword "basealign"
  and an alignment qualifier (quadword, longword, etc).  That is,

  aggregate foo structure typedef basealign quadword;
  ...

  The generated output from this will give the C compiler a set
  of #pragma directives to let it know that the *base* of the
  structure is aligned on the specified boundry.  This allows
  the compiler to generate optimal code for the data in the
  structure.  Then make sure to align your structures to prevent
  any alignment faults & fixups.  Makes a huge difference in
  application performance.  If you look at the output from SDL,
  you can see that it is relatively simple to modify hand coded
  C definitions as well.

  In addition, use the /CHECK qualifier on the SDL command to
  verify that all the fields are on natural boundries.

  Dunno about Fortran. it been years since I wrote a Fortran
  application.  I believe that it tells you to compile:


     OPTIONS/ALIGN=(RECORDS=PACKED,COMMONS=PACKED)


-- 
Frederick G. Kleinsorge       | Standard disclaimer:  All opinions
OpenVMS Engineering           | expressed are mine, and not those of my
Digital Equipment Corporation | employer, or any one else with half a
kleinsorge@star.enet.dec.com  | clue.  No refunds on sale items.