http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194
--- Comment #26 from rguenther at suse dot de <rguenther at suse dot de> 2011-06-16 08:36:21 UTC --- On Wed, 15 Jun 2011, xinliangli at gmail dot com wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194 > > davidxl <xinliangli at gmail dot com> changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |xinliangli at gmail dot com > > --- Comment #23 from davidxl <xinliangli at gmail dot com> 2011-06-15 > 23:14:50 UTC --- > (In reply to comment #22) > > > The DSE patch still leaves 2 redundant stores. > > > > OK, I missed this, reopening... > > > > > The following patch will enable DSE to remove those two stores. Does this > > > look ok? > > > > Calling into the gimplifier from the RTL expander doesn't look appropriate. It also should use create_tmp_var, not create_tmp_reg. But I wonder why memory allocated via assign_temp isn't marked in a way to let dse do its job (I guess dse thinks that memory escapes?). > > More fundamentally, it's a little unfortunate to spill to memory a value > > returned in registers. Can we try to use emit_group_move_into_temps here > > instead (under the appropriate circumstances)? > > It would be nice if the expander does not spill the return into memory in the > first place if possible. On other hand tagging compiler created memory > location with temp decls so that aliaser has the symbolic information seems a > useful mechanism. Sure - but I wonder why assign_temp doesn't do something equivalent that doesn't require a automatic VAR_DECL to be created. Where does the aliaser catch things with the VAR_DECL around that it doesn't without it? Richard.
