Re: Alias analysis - does base_alias_check still work ?

[Richard Henderson <rth at redhat dot com>]

On Fri, Jul 19, 2002 at 03:35:14PM -0700, Richard Henderson wrote:
> The remaining sts/lds pairs are writes then reads from SY.
> We've lost track of the fact that the write is to index I
> and the read from index I+1, and so cannot overlap.

This appears to be the unroller doing stupid things.  The attached
patch1 should cure this.  If this patch can be shown to be a win,
we can axe this section of code properly rather than goto out of it.

I also tried running the unroller during the first loop pass so
that the second loop pass could clean up the giv lossage.  This
didn't work for this case, but I'd be interested in knowing what
effect this has generically.  I.e. a three-way benchmark comparison:

	with -fno-rerun-loop-opt
	without patch2
	with patch2


r~

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