It's trivially impossible with unrestricted aliasing. No compiler can statically predict the properties of an unrestricted arbitrary graph about which, in the limit, absolutely nothing is known until runtime.
Creating arbitrary graphs in memory is not a "theoretical corner case". It corresponds to, for example, Graphviz reading in a graph from user input. Or, if you want something that could technically be done with manual memory management but might as well be an unrestricted graph for all any reasonable analysis could infer, creating a doubly-linked XML/HTML DOM.
Alias analysis failure leading to escape analysis failure is the default case, not the corner case.
I think it is valuable to research what is the best set of restrictions to get reliable escape analysis. For reliable escape analysis for unrestricted case, yes, I think it won't be possible and it isn't worth bothering with at all.
Comments
It's trivially impossible with unrestricted aliasing. No compiler can statically predict the properties of an unrestricted arbitrary graph about which, in the limit, absolutely nothing is known until runtime.
So, because something doesn't work in some theoretical corner cases, it isn't worth bothering with at all?
Creating arbitrary graphs in memory is not a "theoretical corner case". It corresponds to, for example, Graphviz reading in a graph from user input. Or, if you want something that could technically be done with manual memory management but might as well be an unrestricted graph for all any reasonable analysis could infer, creating a doubly-linked XML/HTML DOM.
Alias analysis failure leading to escape analysis failure is the default case, not the corner case.
I think it is valuable to research what is the best set of restrictions to get reliable escape analysis. For reliable escape analysis for unrestricted case, yes, I think it won't be possible and it isn't worth bothering with at all.