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 --git a/gcc/cgraph.cc b/gcc/cgraph.cc
index b923a59..d3cc06b 100644 (file)
--- 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 60da1e8..eb0fa87 100644 (file)
--- 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 (file)
index 0000000..552d374
--- /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>;