potential for controlling memory alignment?

Nicolas Frisby nicolas.frisby at gmail.com
Thu Sep 12 19:28:59 UTC 2013

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.

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