[Bug debug/90336] gcc generates wrong debug information at -O1 to -O3

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90336

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-debug
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2019-05-06
                 CC|                            |aoliva at gcc dot gnu.org
            Version|unknown                     |9.1.0
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.  The main reason is we do not track "memory" changes in debug.
But then we rewrite the initial assignment into SSA and after DCEing that
end up with a debug stmt for the initializer.

It also shows FRE could, as CCP, rewrite no longer address-taken locals
into SSA form.  Or we could make DSE insert debug stmts for killing
stores of register type?