Made some changes.

Feng

________________________________________
From: Feng Xue OS
Sent: Saturday, January 25, 2020 5:54 PM
To: mjambor@suse.cz; Jan Hubicka; gcc-patches@gcc.gnu.org
Subject: [PATCH] Generalized value pass-through for self-recursive function (ipa/pr93203)

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.

This patch is to support these two kinds of value pass-through.
Bootstrapped/regtested on x86_64-linux and aarch64-linux.

Feng

---
2020-01-25  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): Remove code of itersection with unknown
        place holder value.
        (intersect_with_agg_replacements): Likewise.
        (intersect_aggregates_with_edge): Deduce with from pass-through
        jump function for self-recursive.
        (decide_whether_version_node): Remove dead callers and adjust
        order to let a non-self-recursive caller be the first element.