[tree-ssa] live analysis on local static functions

[law@redhat.com]

In message <20031014165254.GK6212@kam.mff.cuni.cz>, Jan Hubicka writes:
 >> On Tue, 2003-10-14 at 12:10, Jan Hubicka wrote:
 >> 
 >> > so we miss the initializer.  I've tracked down the problem to fact that
 >> > variable a does not have flag used set in it's annotation.  It has, when
 >> > I disable the inlining.  It is marked in create_ssa_var_map by seeing
 >> > VUSE attached to the return statement.  With inline enabled the set also
 >> > has VUSE but it's operand is not VAR_DECL itself, but SSA_NAME
 >> > 
 >> 
 >> 
 >> I assume the useless stmt remover ought to check to see if there is a
 >> static initializer in a BIND_EXPR before removing a DECL with an
 >> initializer which is not marked used.    
 >> 
 >> Either that, or has_hidden_use() ought to be set on A.
 >> 
 >> Neither is true right now.
 >> 
 >> There are other choices too :-)
 >
 >This is patch I use in my tree.  Would be OK to apply it?
 >
 >Tue Oct 14 18:51:47 CEST 2003  Jan Hubicka  <jh@suse.cz>
 >	* tree-cfg.c (remove-useless_stmts_and_vars_bind): Fix handling of
 >	local static variables.
I'd rather have a deeper understanding of the problem before applying
this patch.

jeff