Re: TREE_UNCHANGING?

[Richard Henderson <rth at redhat dot com>]

On Thu, May 09, 2002 at 11:00:11PM +0100, Jason Merrill wrote:
> The notion of constancy needs to be expressible at the RTL level.
> Currently RTX_UNCHANGING_P provides that; it does seem to be a problematic
> feature, but if it is removed it should be replaced with another way of
> expressing the same thing.

Yes.

> I suppose it might be feasible to model this using a magic alias set that
> doesn't conflict with alias set 0.  Is that the sort of thing you had in
> mind?

Yes.  A set that really Really means "this mem resides in read-only memory".

Unlike the current RTX_UNCHANGING_P, which perhaps once meant that, but now
appears to mean something akin to "once we get the thing set up, we won't
change it until it goes out of scope".


r~