Re: [PATCH] optimize ia32 memmove

[Jeremy Fitzhardinge]

On Tue, 2003-12-30 at 01:58, Linus Torvalds wrote:
> But then anything that does the loads in ascending order is still ok, so
> it shouldn't matter - by the time "dest" has been overwritten, the source
> data has already been read. And all the "memcpy()"  implementations had
> better do that anyway, in order to get nice memory access patterns. "rep
> movsl" certainly does.

A PPC memcpy may end up clearing the destination before reading the
source (using the cache-line zeroing instruction, to prevent the
destination from being spuriously read to populate the cache line).

	J

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