[Bug tree-optimization/43565] Missed address comparison folding of DECL_COMMONs

[marc@nieper-wisskirchen.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43565

--- Comment #5 from Marc Nieper-Wißkirchen <marc@nieper-wisskirchen.de> ---
If that was possible (that symbols are aliased in the TU in which they are
defined, but not (explicitly) in a TU where they are declared), there would be
the need of a "no_alias" (or "never_alias") attribute, for otherwise, the
optimization we are talking about here would never be possible.