[RFA:] Fix PR rtl-optimization/20466, flow not invalidating knowledge for (mem (mem ...))

[Hans-Peter Nilsson]

> Date: Mon, 21 Mar 2005 16:31:28 -0500
> From: David Edelsohn <dje@watson.ibm.com>

> 	Have you looked at the effect of this patch on other
> architectures, especially architectures that do not allow (mem (mem ...))?

The patch would have no effect on such architectures.

> If this change catches an address that is in a generic alias set, it will
> cause a lot of extra memory traffic.

Only if invalidate_mems_from_set and/or reg_overlap_mentioned_p
actually looked at alias sets, which they don't.

brgds, H-P