Re: [RFC] Don't schedule prefetch INSNs

[Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>]

> > It will be worthwhile if the basic block is a loop body. It might make 
> > sense to prefetch something used in the next loop iteration. Actually 
> > that's what I am trying to do for memcpys.
>
> in that case, the placement of the prefetch inside the loop body is
> more or less irrelevant, no?

In the example described in my other mail the prefetches would be 
completely useless when the get moved over the copy instruction like this:

loop over cache lines (x += cache_line_size, y += cache_line_size):
      copy cache line x to y
      read prefetch x + cache_line_size
      write prefetch y + cache_line_size

The prefetch of the cache lines for the next loop iteration would be too 
close to the memory access.

Bye,

-Andreas-