Hi, On Thu, 14 Jul 2011, Richard Guenther wrote:
> Sure ;) What the middle-end currently lacks is explicit tracking of > what escapes through a function return as opposed to what escapes > somewhere else. Once that is implemented a flag on the PARM_DECL that > tells it to use Fortran dummy argument rules is easy to implement (but > we have issues when that dummy argument is an array descriptor and the > dummy argument rules also apply to the actual array data - as opposed > to, I presume, a dummy argument of fortran aggregate type with a pointer > member). And the latter is also why such a flag/attribute needs to be ultimately placed on the type, so that we can form pointers to such parm_decls (or even members of array descriptors) without loosing the special guarantees, ala "not clobbered by calls". That or flags on the MEM_REF (which magically needs to be set then, most probably again, by tracking such flag from the PARM_DECL, through types to the MEM_REF). > It's on my list to solve that function-return-escape thing, but as usual > my list of things to implement is rather large ;) > > For the record, the current way of using C restrict works reasonably > well and I don't think we will gain very much in real-world performance > if not using it Did you really want to say this? Because I'm very sure we actually loose very much in real-world performance if we wouldn't be using it (or some alterntive that is specified somewhat cleaner). Ciao, Michael.
