Parallel Programming

[DanKarron at UCBVAX.BERKELEY.EDU]

I happly used the -align16 flag and did not notice anything. Then I
started getting very weird crashes with innocent operations with chars'
and shorts. DBX would indicate a buss error and not show anything wrong
at the source line.

Serious hacking showed that the errors were alignment errors that were
caused by attempting to assign unaligned shorts to something. My
queries to sgi indicated that the -align16, -align32 options were buggy.

Then the question arose why use the -alignNN options, and I pointed to the
man page. After more up and back with sgi, it was determined that you
DON"T need the -alignNN option. You do need 16 BYTE alignment for somethings,
but I don't know what for.

This was a weird one, and many people apparently can live very happly without
ever having problems with the -alignNN options. I appreciate sgi being honest
and admiting the problem.


>Date: Thu, 31 Jan 91 09:10:57 EST
>From: "Lance M. Optican - LMO" <uunet.uu.net!lsr-vax!lmo>
>Message-Id: <9101311410.AA02066@>
>To: uunet.uu.net!uunet!brl.mil!info-iris
>Subject: Parallel Programming
>
>
>	Following TFM, I diligently incluided the "-align16" flag
>in my compilations.  Now I see info-iris mail saying you don't need
>this flag.
>
>	What is the truth?!
>
>----------------------------------------------+--------------------------
>   Lance M. Optican			      | uunet.uu.net!lsr-vax!lmo 
>   Laboratory of Sensorimotor Research	      | lsr-vax!lmo at uunet.uu.net
>   National Eye Institute, NIH, Bethesda, MD  |	(301) 496-3549    
>----------------------------------------------+--------------------------
>
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