[gcc r12-8202] cgraph: Fix up semantic_interposition handling [PR105306]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:2a6d372ba96cc0836bfd46579ad78c1ee5a3cf8a

commit r12-8202-g2a6d372ba96cc0836bfd46579ad78c1ee5a3cf8a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Apr 20 09:24:18 2022 +0200

    cgraph: Fix up semantic_interposition handling [PR105306]
    
    cgraph_node has a semantic_interposition flag which should mirror
    opt_for_fn (decl, flag_semantic_interposition).  But it actually is
    initialized not from that, but from flag_semantic_interposition in the
      explicit symtab_node (symtab_type t)
        : type (t), resolution (LDPR_UNKNOWN), definition (false), alias (false),
    ...
          semantic_interposition (flag_semantic_interposition),
    ...
          x_comdat_group (NULL_TREE), x_section (NULL)
      {}
    ctor.  I think that might be fine for varpool nodes, but since
    flag_semantic_interposition is now implied from -Ofast it isn't correct
    for cgraph nodes, unless we guarantee that cgraph node for a particular
    function decl is always created while that function is
    current_function_decl.  That is often the case, but not always as the
    following function shows.
    Because symtab_node's ctor doesn't know for which decl the cgraph node
    is being created, the following patch keeps that as is, but updates it from
    opt_for_fn (decl, flag_semantic_interposition) when we know that, or for
    clones copies that flag (often it is then overridden in
    set_new_clone_decl_and_node_flags, but not always).
    
    2022-04-20  Jakub Jelinek  <jakub@redhat.com>
    
            PR ipa/105306
            * cgraph.cc (cgraph_node::create): Set node->semantic_interposition
            to opt_for_fn (decl, flag_semantic_interposition).
            * cgraphclones.cc (cgraph_node::create_clone): Copy over
            semantic_interposition flag.
    
            * g++.dg/opt/pr105306.C: New test.

Diff:
---
 gcc/cgraph.cc                       |  1 +
 gcc/cgraphclones.cc                 |  1 +
 gcc/testsuite/g++.dg/opt/pr105306.C | 13 +++++++++++++
 3 files changed, 15 insertions(+)

diff --git a/gcc/cgraph.cc b/gcc/cgraph.cc
index b923a59ab0c..d3cc06bbaed 100644
--- a/gcc/cgraph.cc
+++ b/gcc/cgraph.cc
@@ -507,6 +507,7 @@ cgraph_node::create (tree decl)
   gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
 
   node->decl = decl;
+  node->semantic_interposition = opt_for_fn (decl, flag_semantic_interposition);
 
   if ((flag_openacc || flag_openmp)
       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
diff --git a/gcc/cgraphclones.cc b/gcc/cgraphclones.cc
index 60da1e867c8..eb0fa87b554 100644
--- a/gcc/cgraphclones.cc
+++ b/gcc/cgraphclones.cc
@@ -394,6 +394,7 @@ cgraph_node::create_clone (tree new_decl, profile_count prof_count,
   new_node->versionable = versionable;
   new_node->can_change_signature = can_change_signature;
   new_node->redefined_extern_inline = redefined_extern_inline;
+  new_node->semantic_interposition = semantic_interposition;
   new_node->tm_may_enter_irr = tm_may_enter_irr;
   new_node->externally_visible = false;
   new_node->no_reorder = no_reorder;
diff --git a/gcc/testsuite/g++.dg/opt/pr105306.C b/gcc/testsuite/g++.dg/opt/pr105306.C
new file mode 100644
index 00000000000..552d37491bc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr105306.C
@@ -0,0 +1,13 @@
+// PR ipa/105306
+// { dg-do compile }
+// { dg-options "-Ofast" }
+
+#pragma GCC optimize 0
+template <typename T> void foo (T);
+struct B { ~B () {} };
+struct C { B f; };
+template <typename> struct E {
+  void bar () { foo (g); }
+  C g;
+};
+template class E<char>;