[Bug tree-optimization/13962] [tree-ssa] make "fold" use alias information to optimize pointer comparisons

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=13962

--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
For GCC 7 we can now do ptr != decl (for certain kinds of decls).  I have
patches extending this to the ptr != ptr case but they need work because PTA
needs to handle points-to NULL (aka nothing) and STRING_CST (and LABEL_DECL
and FUNCTION_DECL, etc.) conservatively.  Comparing LABEL_DECL against
FUNCTION_DECL will also be interesting, so not sure if we can ever make
this work (maybe glob LABEL_DECLs with their containing FUNCTION_DECLs for
PTA purposes).