[Bug bootstrap/65150] [5 Regression] r220875 causes bootstrap failure on x86_64 darwin

["iains at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65150

--- Comment #18 from Iain Sandoe <iains at gcc dot gnu.org> ---
if I understood the conversation in irc correctly, Honza you were suggesting
the following modification (to use alias->can_remove_if_no_direct_calls_p() as
the criterion for deciding on eligibility for removal)?

on x86_64-darwin12, bootstrap succeeds with the following; C test regressions
seem much the same as for comment #6 - preliminary tests only.
----

diff --git a/gcc/ipa-icf.c b/gcc/ipa-icf.c
index e1af8bf..0c3d668 100644
--- a/gcc/ipa-icf.c
+++ b/gcc/ipa-icf.c
@@ -662,6 +662,7 @@ sem_function::merge (sem_item *alias_item)
       redirect_callers
        = (!original_discardable
           && !DECL_COMDAT_GROUP (alias->decl)
+          && !DECL_VIRTUAL_P (alias->decl)
           && alias->get_availability () > AVAIL_INTERPOSABLE
           && original->get_availability () > AVAIL_INTERPOSABLE
           && !alias->instrumented_version);
@@ -724,15 +725,18 @@ sem_function::merge (sem_item *alias_item)

       /* The alias function is removed if symbol address
          does not matter.  */
-      if (!alias_address_matters)
-       alias->remove ();
+      if (alias->can_remove_if_no_direct_calls_p())
+       {
+         alias->remove ();

-      if (dump_file && redirected)
-       fprintf (dump_file, "Callgraph local calls have been redirected.\n\n");
+         if (dump_file && redirected)
+           fprintf (dump_file, "Callgraph local calls have been
redirected.\n\n");
+         return true;
+       }
     }
-  /* If the condtion above is not met, we are lucky and can turn the
+  /* If the condition above is not met, we are lucky and can turn the
      function into real alias.  */
-  else if (create_alias)
+  if (create_alias)
     {
       alias->icf_merged = true;
       if (local_original->lto_file_data
@@ -762,7 +766,7 @@ sem_function::merge (sem_item *alias_item)
          if (dump_file)
            fprintf (dump_file, "Callgraph thunk cannot be created because of
COMDAT\n");

-         return 0;
+         return false;
        }

       if (DECL_STATIC_CHAIN (alias->decl))
@@ -770,7 +774,7 @@ sem_function::merge (sem_item *alias_item)
          if (dump_file)
            fprintf (dump_file, "Thunk creation is risky for static-chain
functions.\n\n");

-         return 0;
+         return false;
         }

       alias->icf_merged = true;