PR tree-optimization/47679
        * tree-ssa-dom.c (avail_exprs_stack): No longer file scoped.  Move
        it here ...
        (dom_opt_dom_walker): New private member holding the avail_exprs_stack
        object.  Update constructor.
        (pass_dominator::execute):  Corresponding chagnes to declaration
        and initialization of avail_exprs_stack.  Update constructor call
        for dom_opt_dom_walker object.
        (lookup_avail_expr, record_cond): Accept additional argument.  Pass
        it down to children as needed.
        (record_equivalences_from_incoming_edge): Likewise.
        (eliminate_redundant_computations): Likewise.
        (record_equivalences_from_stmt): Likewise.
        (simplify_stmt_for_jump_threading): Likewise.
        (record_temporary_equivalences): Likewise.
        (optimize_stmt): Likewise.
        (dom_opt_dom_walker::thread_across_edge): Update access to
        avail_exprs_stack object and pass it to children as needed.
        (dom_opt_dom_walker::before_dom_children): Similarly.
        (dom_opt_dom_walker::after_dom_children): Similarly.
        * tree-ssa-threadedge.c (pfn_simplify): New typedef.
        (record_temporary_equivalences_from_stmts_at_dest): Use new typedef.
        Add avail_expr_stack argument.  Pass it to children as needed.
        (dummy_simplify): Likewise.
        (simplify_control_stmt_condition): Likewise.
        (thread_around_empty_blocks): Likewise.
        (thread_through_normal_block): Likewise.
        (thread_across_edge): Likewise.
        * tree-ssa-threadedge.h (thread_across_edge): Update prototype.
        * tree-vrp.c (simplify_stmt_for_jump_threading): Update.

From-SVN: r227931