[Bug c/20319] -fkeep-static-consts with -O asserted doesn't keep consts

["gary at intrepid dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From gary at intrepid dot com  2005-03-04 21:54 -------


Here is some detail on my proposed change in behavior:

1) Change the default setting to -fno-keep-static-consts:

/* Nonzero means that we should emit static const variables
   regardless of whether or not optimization is turned on.  */ 
                            
int flag_keep_static_consts = 0;

2) have flag_keep_static_consts affect only the behavior of the
compiler when 'optimize' is asserted:

Change the logic in wrapup_global_declarations (toplev.c) to read:

              else if (TREE_READONLY (decl) && !TREE_PUBLIC (decl)
                       && (optimize && !flag_keep_static_consts)
                           || DECL_ARTIFICIAL (decl))) 
                needed = 0;

This change would imply that:

1) -fkeep-static-consts and -fno-keep-static-consts will have no effect
at -O0.  Presently, -fno-keep-static-consts would eliminate the unreferenced
static const variable if it isn't referenced.  This would no longer be
the case. At -O0, the compiler would always leave unrefereced static
consts alone.

2) If optimization is asserted (ie, -O1 and above), then always eliminate
static const's that aren't referenced, unless -fkeep-static-consts is
asserted.




-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20319