Strongly Specify Alignment for FFI Allocation
duncan.coutts at googlemail.com
Mon Sep 28 09:09:41 EDT 2009
On Sat, 2009-09-26 at 04:20 +0100, Brandon S. Allbery KF8NH wrote:
> On Sep 25, 2009, at 07:54 , Duncan Coutts wrote:
> > pessimistic. We could do better on machines that are tolerant of
> > misaligned memory accesses such as x86. We'd need to use cpp to switch
> Hm. I thought x86 could be tolerant (depending on a cpu configuration
> bit) but the result was so slow that it wasn't worth it?
It's slow and you would not want to do it much, however I think it's
still comparable in speed to doing a series of byte reads/writes and
using bit twiddling to convert to/from the larger word type. It's
probably also faster to do an unaliged operation sometimes than to do an
alignment test each time and call a special unaliged version.
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