re PR tree-optimization/15982 (ICE in tree-ssa-pre due to GVN-PRE)

re PR tree-optimization/15982 (ICE in tree-ssa-pre due to GVN-PRE)

2004-06-21  Daniel Berlin  <dberlin@dberlin.org>

    Fix PR optimization/15982
    * tree-ssa-pre.c: Update a few comments and todos to
    reflect constants change.
    (get_value_handle): Constants now value number to themselves.
    (lookup): Constants lookup to themselves.
    (add_to_value): Adjust to always be on.
    (set_contains_value): Adjust for constants change.
    (find_leader): Ditto.
    (phi_translate): 'r' nodes are never ANTIC right now.
    (valid_in_set): Ditto.
    (get_expr_set): New function.
    (find_or_generate_expression): New function, broken out from
    insert_aux.
    (create_expression_by_pieces): Ditto, plus additional
    machinery to handle complex values.
    (compute_avail): Remove dead RETURN_EXPR handling.

From-SVN: r83453