Fix ICE on inlined thunks

[Jan Hubicka]

Hi,
this patch fixes ICE in somewhat rare situation when thunk is inlined and
later promoted into a comdat group.  The reduced testcase in the PR no longer
reproduces as it relies on quite fragile inlining decisions, but it would
be nice to have re-reduced one.

Bootstrapped/regtested x86_64-linux, comitted to trunk so far.

Honza

        PR ipa/80763
        * ipa-comdats.c (set_comdat_group): Only set comdat group of real
        symbols; not inline clones.

Index: ipa-comdats.c
===================================================================
--- ipa-comdats.c       (revision 256332)
+++ ipa-comdats.c       (working copy)
@@ -211,8 +211,11 @@ set_comdat_group (symtab_node *symbol,
   symtab_node *head = (symtab_node *)head_p;
 
   gcc_assert (!symbol->get_comdat_group ());
-  symbol->set_comdat_group (head->get_comdat_group ());
-  symbol->add_to_same_comdat_group (head);
+  if (symbol->real_symbol_p ())
+    {
+      symbol->set_comdat_group (head->get_comdat_group ());
+      symbol->add_to_same_comdat_group (head);
+    }
   return false;
 }