Re: [PATCH] Copyprop through aggregates.

[Diego Novillo <dnovillo at redhat dot com>]

On 02/04/06 07:35, Richard Guenther wrote:

> 	* tree-flow.h (get_stmt_rhs_def_stmt): Declare.
> 	(offset_overlaps_with_access): Likewise.
> 	* tree-flow-inline.h (offset_overlaps_with_access): New
> 	inline function definition.
> 	* tree-ssa-structalias.c (offset_overlaps_with_access):
> 	Remove.
> 	* tree-dfa.c (get_ref_base_and_extent): Remove assertion.
> 	Deal with structures ending in arrays and such unknown
> 	extent.
> 	(get_stmt_rhs_def_stmt): New helper walking virtual
> 	use-def chains.
> 	* tree-ssa-copy.c (stmt_may_generate_copy): Adjust for
> 	copyprop through aggregates.
> 	(copy_prop_visit_stmt): Likewise.
> 	(copy_prop_visit_assignment): For SSA_NAMEs defined by
> 	a memory load walk the virtual use-def chain searching for
> 	a definition of the memory load that is an SSA_NAME and
> 	use that for propagation.
> 
Not OK.  As we discussed on IRC recently, you are working around
limitations in the propagation engine.  The fact that you had to add an
alternate use-def chain walker suggests that the approach is faulty.

I don't quite recall whether you were going to attempt extending the
propagation engine or were going to wait for me.  It will be a while
until I can get around to it, unfortunately.