potential for controlling memory alignment?

[Carter Schonwald]

i created a ticket on trac
http://ghc.haskell.org/trac/ghc/ticket/8279


On Thu, Sep 12, 2013 at 3:46 PM, Carter Schonwald <
carter.schonwald at gmail.com> wrote:

> Reid Barton was just noticing some  alignment perf issues  and talking
> about it on #ghc / #haskell-llvm
>
> probably worth documenting it in a ticket!
>
>
>
> On Thu, Sep 12, 2013 at 3:28 PM, Nicolas Frisby <nicolas.frisby at gmail.com>wrote:
>
>> On my laptop, a program showed a consistent slowdown with -fdicts-strict
>>
>> I didn't find any obvious causes in the Core differences, so I turned to
>> Intel's Performance Counter Monitor for measurements. After trying a few
>> counters, I eventuall saw that there are about an order of magnitude more
>> misaligned memory loads with -fdicts-strict than without, so I think that
>> may be a significant part of the slowdown. I'm not sure if these are code
>> or data reads.
>>
>> Can anyone suggest how to validate this hypothesis about misaligned reads?
>>
>> A subsequent commit has changed the behavior I was seeing, so I'm not
>> interested in alternatives means to determine if -fdicts-strict is somehow
>> at fault — I'm just asking specifically about data/code memory alignment in
>> GHC and how to diagnose/experiment with it.
>>
>> Thanks.
>>
>>
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>>
>>
>
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