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Re: Alignment problems

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On 12/ 4/11 01:23 PM, Jorgen Grahn wrote:
> On Thu, 2011-12-01, Ian Collins wrote:
>> On 12/ 2/11 09:50 AM, jacob navia wrote:
> ...
>>> The problem is further complicated by the fact that under SPARC
>>> modern versions you do NOT need to align anything since the OS
>>> catches the unaligned trap, and loads the double with 2 instructions.
>>
>> That's an expensive option, or at least it used to be on older
>> processors.  The Sun compilers support misaligned access (through the
>> -xmemalign option), but transferring to trap handler is a significant
>> overhead.
>
> *sigh*
>
> Are people still playing that stupid game?  If it's an overhead of
> 100x or 1000x like I've seen on some ARM systems, it's much better to
> crash.  In one project I'm in, we're kind of sorry we abandoned the
> Sparc architecture -- because it reveals problems like this one.

The last time I played that "stupid game" I had little choice.  The code 
I was testing was developed for an embedded 68K target, where alignment 
wasn't an issue.

That compiler option really is a quick and nasty hack to help porting 
poor code to Sparc.

-- 
Ian Collins

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Thread

Alignment problems jacob navia <jacob@spamsink.net> - 2011-12-01 01:05 +0100
  Re: Alignment problems Ian Collins <ian-news@hotmail.com> - 2011-12-01 13:15 +1300
  Re: Alignment problems pacman@kosh.dhis.org (Alan Curry) - 2011-12-01 02:57 +0000
  Re: Alignment problems gordonb.hpln0@burditt.org (Gordon Burditt) - 2011-11-30 21:27 -0600
  Re: Alignment problems jacob navia <jacob@spamsink.net> - 2011-12-01 13:38 +0100
    Re: Alignment problems pacman@kosh.dhis.org (Alan Curry) - 2011-12-01 20:38 +0000
      Re: Alignment problems jacob navia <jacob@spamsink.net> - 2011-12-01 21:50 +0100
        Re: Alignment problems Ian Collins <ian-news@hotmail.com> - 2011-12-02 10:27 +1300
          Re: Alignment problems Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-12-04 00:23 +0000
            Re: Alignment problems Ian Collins <ian-news@hotmail.com> - 2011-12-04 13:31 +1300
        Re: Alignment problems ImpalerCore <jadill33@gmail.com> - 2011-12-01 14:34 -0800
  Re: Alignment problems "BartC" <bc@freeuk.com> - 2011-12-01 13:46 +0000
    Re: Alignment problems Keith Thompson <kst-u@mib.org> - 2011-12-01 14:15 -0800
      Re: Alignment problems David Thompson <dave.thompson2@verizon.net> - 2012-01-19 02:44 -0500
  Re: Alignment problems "James" <no@spam.invalid> - 2011-12-01 19:43 -0800
  Re: Alignment problems "Brain" <Brian@myhome.com> - 2011-12-04 02:47 -0600
    Re: Alignment problems Keith Thompson <kst-u@mib.org> - 2011-12-04 08:26 -0800
      Re: Alignment problems Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-08 00:12 +0200
        Re: Alignment problems Keith Thompson <kst-u@mib.org> - 2011-12-07 22:31 -0800
          Re: Alignment problems lovecreatesbeauty <lovecreatesbeauty@gmail.com> - 2011-12-08 21:43 -0800
            Re: Alignment problems Keith Thompson <kst-u@mib.org> - 2011-12-09 01:31 -0800
              Re: Alignment problems Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-12-09 14:15 +0200

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