On Tue, Mar 27, 2012 at 6:13 PM, Ulrich Weigand <uweig...@de.ibm.com> wrote:
>> Since fixing reload issues is some kind of black magic, I'd like to >> ask Ulrich and Richard for their opinion on this approach. > > Well, generally speaking, reload makes a lot of assumptions on how > addresses can look like; it needs to, since if a target rejects an > address as invalid as-is, reload must fix it up -- and it can do > so only by making assumptions ... > > Allowing a random UNSPEC as part of valid (non-strict) addresses > makes it really impossible for reload to understand what's going > on. Given that, I'd tend to agree that *if* you do that, you > then also have to help reload how to deal with such addresses > by providing a legitimize_reload_address hook as you did. > > Now, in this particular case, there might be another option to > avoid this hassle completely: I understand that this UNSPEC is > simply a magic marker to make the address use the fs: or gs: > segment override, right? Now that GCC supports address spaces, > it might be possible to model fs:/gs: relative addresses instead > by using a non-standard address space ... This is an interesting idea, I will look into it. (BTW: For now, I have just committed the proposed fixup). Thanks, Uros.
