http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53774
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|NEW |ASSIGNED
AssignedTo|unassigned at gcc dot |rguenth at gcc dot gnu.org
|gnu.org |
--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-06-26
14:24:13 UTC ---
I am testing instead
@@ -2299,8 +2299,16 @@ rewrite_expr_tree (gimple stmt, unsigned
print_gimple_stmt (dump_file, stmt, 0, 0);
}
- gimple_assign_set_rhs1 (stmt, oe1->op);
- gimple_assign_set_rhs2 (stmt, oe2->op);
+ if (tree_swap_operands_p (oe1->op, oe2->op, true))
+ {
+ gimple_assign_set_rhs1 (stmt, oe2->op);
+ gimple_assign_set_rhs2 (stmt, oe1->op);
+ }
+ else
+ {
+ gimple_assign_set_rhs1 (stmt, oe1->op);
+ gimple_assign_set_rhs2 (stmt, oe2->op);
+ }
update_stmt (stmt);
if (rhs1 != oe1->op && rhs1 != oe2->op)
remove_visited_stmt_chain (rhs1);
which fixes it. OTOH there are many other places reassoc adjusts
stmt operands (but it eventually relies on operand order). Adding
a canonicalize_operand_order_and_update_stmt () wherever we
call update_stmt afer adjusting operands might be better ... or
simply calling fold_stmt on all stmts we touch which does the re-ordering, too.
Well, I'm not really sure where we should enforce canonical ordering ...
