[PATCH] Do not remove ifunc_resolver in LTO.

[Martin Liška]

Hi.

The patch prevents a ifunc alias from removal in remove unreachable nodes.
Note that ifunc alias lives in a COMDAT section and so that
cgraph_node::can_remove_if_no_direct_calls_and_refs_p returned true for it.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
I was unable to create a lto test-case where a linked binary could be
scanned for assembly.

Ready to be installed?
Thanks,
Martin

gcc/ChangeLog:

2020-04-20  Martin Liska  <mli...@suse.cz>

        PR lto/94659
        * cgraph.h (cgraph_node::can_remove_if_no_direct_calls_and_refs_p):
        Do not remove ifunc_resolvers in remove unreachable nodes in LTO.
---
 gcc/cgraph.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)



diff --git a/gcc/cgraph.h b/gcc/cgraph.h
index 43de3b4a8ac..5ddeb65269b 100644
--- a/gcc/cgraph.h
+++ b/gcc/cgraph.h
@@ -3162,7 +3162,7 @@ cgraph_node::can_remove_if_no_direct_calls_and_refs_p (void)
     return false;
   /* Only COMDAT functions can be removed if externally visible.  */
   if (externally_visible
-      && (!DECL_COMDAT (decl)
+      && ((!DECL_COMDAT (decl) || ifunc_resolver)
 	  || forced_by_abi
 	  || used_from_object_file_p ()))
     return false;