Generalized value pass-through for self-recusive function (PR ipa/93203)

Generalized value pass-through for self-recusive function (PR ipa/93203)

Besides simple pass-through (aggregate) jump function, arithmetic (aggregate)
jump function could also bring same (aggregate) value as parameter passed-in
for self-feeding recursive call.  For example,

      f1 (int i)    /*  normal jump function */
         {
            f1 (i & 1);
         }

Suppose i is 0, recursive propagation via (i & 1) also gets 0, which
can be seen as a simple pass-through of i.

      f2 (int *p)  /* aggregate jump function */
         {
            int t = *p & 1;
            f2 (&t);
         }
Likewise, if *p is 0, (*p & 1) is also 0, and &t is an aggregate simple
pass-through of p.

2020-02-10  Feng Xue  <fxue@os.amperecomputing.com>

        PR ipa/93203
        * ipa-cp.c (ipcp_lattice::add_value): Add source with same call edge
        but different source value.
        (adjust_callers_for_value_intersection): New function.
        (gather_edges_for_value): Adjust order of callers to let a
        non-self-recursive caller be the first element.
        (self_recursive_pass_through_p): Add a new parameter "simple", and
        check generalized self-recursive pass-through jump function.
        (self_recursive_agg_pass_through_p): Likewise.
        (find_more_scalar_values_for_callers_subset): Compute value from
        pass-through jump function for self-recursive.
        (intersect_with_plats): Cleanup previous implementation code for value
        itersection with self-recursive call edge.
        (intersect_with_agg_replacements): Likewise.
        (intersect_aggregates_with_edge): Deduce value from pass-through jump
        function for self-recursive call edge.  Cleanup previous implementation
        code for value intersection with self-recursive call edge.
        (decide_whether_version_node): Remove dead callers and adjust order
        to let a non-self-recursive caller be the first element.

        PR ipa/93203
        * g++.dg/ipa/pr93203.C: New test.