* tree-ssa-dom.c (avail_exprs_stack): New global varray.
        (struct dom_walk_block_data): Remove avail_exprs member.
        (tree_ssa_dominator_optimize): Initialize avail_exprs_stack.
        (lookup_avail_expr): No longer need to pass in address of
        the block local available exprs stack.  All callers changed.
        (simplify_cond_and_lookup_avail_expr): Similarly.
        (simplify_switch_and_lookup_avail_expr): Similarly.
        (get_eq_expr_value, record_cond): Likewise.
        (record_dominating_conditions): Likewise.
        (update_rhs_and_lookup_avail_expr): Likewise.
        (record_equivalences_from_stmt): Likewise.
        (dom_opt_initialize_block_local_data): No longer test state of
        block local avail_exprs.
        (dom_opt_initialize_block): Mark unwind point in the global
        avail_expr stack.
        (remove_expressions_from_table): Update to unwind to the
        most recent unwind marker in the global avail_expr stack.
        All callers changed.
        (dom_opt_finalize_block): Mark unwind point in the global
        avail_expr stack as needed.
        (record_cond): Push elements into the global avail_exprs stack.

From-SVN: r87532