c++: support target attr for DECL_LOCAL_DECL_P fns [PR99108]

We crash when target attribute get_function_versions_dispatcher is called
for a function that is not registered in call graph.  This was happening
because we were calling it for the function-local decls that aren't in the
symbol table, instead of the corresponding namespace-scope decls that are.

gcc/cp/ChangeLog:

	PR c++/99108
	* call.c (get_function_version_dispatcher): Handle
	DECL_LOCAL_DECL_P.
	* decl.c (maybe_version_functions): Likewise.
	(maybe_mark_function_versioned): New.
	* name-lookup.c (push_local_extern_decl_alias): No longer static.
	* name-lookup.h (push_local_extern_decl_alias): Adjust.

gcc/testsuite/ChangeLog:

	PR c++/99108
	* g++.target/i386/pr99108.C: New test.

Co-authored-by: Jason Merrill <jason@redhat.com>

5 files changed, 52 insertions, 10 deletions

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 33278b5..29f4b50 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -8469,6 +8469,9 @@ get_function_version_dispatcher (tree fn)
 {
   tree dispatcher_decl = NULL;
 
+  if (DECL_LOCAL_DECL_P (fn))
+    fn = DECL_LOCAL_DECL_ALIAS (fn);
+
   gcc_assert (TREE_CODE (fn) == FUNCTION_DECL
 	      && DECL_FUNCTION_VERSIONED (fn));
 
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 1b671ce..56092eb 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -1110,6 +1110,21 @@ decls_match (tree newdecl, tree olddecl, bool record_versions /* = true */)
   return types_match;
 }
 
+/* Mark DECL as versioned if it isn't already.  */
+
+static void
+maybe_mark_function_versioned (tree decl)
+{
+  if (!DECL_FUNCTION_VERSIONED (decl))
+    {
+      DECL_FUNCTION_VERSIONED (decl) = 1;
+      /* If DECL_ASSEMBLER_NAME has already been set, re-mangle
+	 to include the version marker.  */
+      if (DECL_ASSEMBLER_NAME_SET_P (decl))
+	mangle_decl (decl);
+    }
+}
+
 /* NEWDECL and OLDDECL have identical signatures.  If they are
    different versions adjust them and return true.
    If RECORD is set to true, record function versions.  */
@@ -1120,18 +1135,22 @@ maybe_version_functions (tree newdecl, tree olddecl, bool record)
   if (!targetm.target_option.function_versions (newdecl, olddecl))
     return false;
 
-  if (!DECL_FUNCTION_VERSIONED (olddecl))
+  maybe_mark_function_versioned (olddecl);
+  if (DECL_LOCAL_DECL_P (olddecl))
     {
-      DECL_FUNCTION_VERSIONED (olddecl) = 1;
-      if (DECL_ASSEMBLER_NAME_SET_P (olddecl))
-	mangle_decl (olddecl);
+      olddecl = DECL_LOCAL_DECL_ALIAS (olddecl);
+      maybe_mark_function_versioned (olddecl);
     }
 
-  if (!DECL_FUNCTION_VERSIONED (newdecl))
+  maybe_mark_function_versioned (newdecl);
+  if (DECL_LOCAL_DECL_P (newdecl))
     {
-      DECL_FUNCTION_VERSIONED (newdecl) = 1;
-      if (DECL_ASSEMBLER_NAME_SET_P (newdecl))
-	mangle_decl (newdecl);
+      /* Unfortunately, we can get here before pushdecl naturally calls
+	 push_local_extern_decl_alias, so we need to call it directly.  */
+      if (!DECL_LOCAL_DECL_ALIAS (newdecl))
+	push_local_extern_decl_alias (newdecl);
+      newdecl = DECL_LOCAL_DECL_ALIAS (newdecl);
+      maybe_mark_function_versioned (newdecl);
     }
 
   if (record)
diff --git a/gcc/cp/name-lookup.c b/gcc/cp/name-lookup.c
index 9382a47..a6257f5 100644
--- a/gcc/cp/name-lookup.c
+++ b/gcc/cp/name-lookup.c
@@ -3374,7 +3374,7 @@ set_decl_context_in_fn (tree ctx, tree decl)
 /* DECL is a local extern decl.  Find or create the namespace-scope
    decl that it aliases.  Also, determines the linkage of DECL.  */
 
-static void
+void
 push_local_extern_decl_alias (tree decl)
 {
   if (dependent_type_p (TREE_TYPE (decl)))
@@ -3408,7 +3408,7 @@ push_local_extern_decl_alias (tree decl)
 
       if (binding && TREE_CODE (binding) != TREE_LIST)
 	for (ovl_iterator iter (binding); iter; ++iter)
-	  if (decls_match (*iter, decl))
+	  if (decls_match (decl, *iter, /*record_versions*/false))
 	    {
 	      alias = *iter;
 	      break;
diff --git a/gcc/cp/name-lookup.h b/gcc/cp/name-lookup.h
index 67e923f..f63c4f5 100644
--- a/gcc/cp/name-lookup.h
+++ b/gcc/cp/name-lookup.h
@@ -453,6 +453,7 @@ extern void cp_emit_debug_info_for_using (tree, tree);
 
 extern void finish_nonmember_using_decl (tree scope, tree name);
 extern void finish_using_directive (tree target, tree attribs);
+void push_local_extern_decl_alias (tree decl);
 extern tree pushdecl (tree, bool hiding = false);
 extern tree pushdecl_outermost_localscope (tree);
 extern tree pushdecl_top_level (tree);
diff --git a/gcc/testsuite/g++.target/i386/pr99108.C b/gcc/testsuite/g++.target/i386/pr99108.C
new file mode 100644
index 0000000..b1f0a71
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr99108.C
@@ -0,0 +1,19 @@
+/* PR c++/99108 */
+/* { dg-require-ifunc "" }  */
+
+struct A {
+  template <class T>
+  void foo(T);
+};
+template <class T>
+void A::foo(T)
+{
+  int f(void) __attribute__((target("default")));
+  int f(void) __attribute__((target("arch=atom")));
+  int b = f();
+}
+void bar(void)
+{
+  A c;
+  c.foo(7);
+}