From 2a10a2c0689db280ee3a94164504b7196b8370f4 Mon Sep 17 00:00:00 2001
From: Tobias Burnus <tobias@codesourcery.com>
Date: Mon, 28 Sep 2020 18:08:05 +0200
Subject: [PATCH] OpenMP: Handle cpp_implicit_alias in declare-target discovery
 (PR96390)

gcc/ChangeLog:

	PR middle-end/96390
	* omp-offload.c (omp_discover_declare_target_tgt_fn_r): Handle
	alias nodes.

libgomp/ChangeLog:

	PR middle-end/96390
	* testsuite/libgomp.c++/pr96390.C: New test.
	* testsuite/libgomp.c-c++-common/pr96390.c: New test.
---
 gcc/omp-offload.c                             | 44 ++++++++++++++---
 libgomp/testsuite/libgomp.c++/pr96390.C       | 49 +++++++++++++++++++
 .../testsuite/libgomp.c-c++-common/pr96390.c  | 26 ++++++++++
 3 files changed, 113 insertions(+), 6 deletions(-)
 create mode 100644 libgomp/testsuite/libgomp.c++/pr96390.C
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/pr96390.c

diff --git a/gcc/omp-offload.c b/gcc/omp-offload.c
index 32c2485abd4..a89275b3a7a 100644
--- a/gcc/omp-offload.c
+++ b/gcc/omp-offload.c
@@ -196,21 +196,53 @@ omp_declare_target_var_p (tree decl)
 static tree
 omp_discover_declare_target_tgt_fn_r (tree *tp, int *walk_subtrees, void *data)
 {
-  if (TREE_CODE (*tp) == FUNCTION_DECL
-      && !omp_declare_target_fn_p (*tp)
-      && !lookup_attribute ("omp declare target host", DECL_ATTRIBUTES (*tp)))
+  if (TREE_CODE (*tp) == FUNCTION_DECL)
     {
+      tree decl = *tp;
       tree id = get_identifier ("omp declare target");
-      if (!DECL_EXTERNAL (*tp) && DECL_SAVED_TREE (*tp))
-	((vec<tree> *) data)->safe_push (*tp);
-      DECL_ATTRIBUTES (*tp) = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (*tp));
       symtab_node *node = symtab_node::get (*tp);
       if (node != NULL)
 	{
+	  while (node->alias_target)
+	    {
+	      if (!omp_declare_target_fn_p (node->decl)
+		  && !lookup_attribute ("omp declare target host",
+					DECL_ATTRIBUTES (node->decl)))
+		{
+		  node->offloadable = 1;
+		  DECL_ATTRIBUTES (node->decl)
+		    = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (node->decl));
+		}
+	      node = symtab_node::get (node->alias_target);
+	    }
+	  symtab_node *new_node = node->ultimate_alias_target ();
+	  decl = new_node->decl;
+	  while (node != new_node)
+	    {
+	      if (!omp_declare_target_fn_p (node->decl)
+		  && !lookup_attribute ("omp declare target host",
+					DECL_ATTRIBUTES (node->decl)))
+		{
+		  node->offloadable = 1;
+		  DECL_ATTRIBUTES (node->decl)
+		    = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (node->decl));
+		}
+	      gcc_assert (node->alias && node->analyzed);
+	      node = node->get_alias_target ();
+	    }
 	  node->offloadable = 1;
 	  if (ENABLE_OFFLOADING)
 	    g->have_offload = true;
 	}
+      if (omp_declare_target_fn_p (decl)
+	  || lookup_attribute ("omp declare target host",
+				    DECL_ATTRIBUTES (decl)))
+	return NULL_TREE;
+
+      if (!DECL_EXTERNAL (decl) && DECL_SAVED_TREE (decl))
+	((vec<tree> *) data)->safe_push (decl);
+      DECL_ATTRIBUTES (decl) = tree_cons (id, NULL_TREE,
+					  DECL_ATTRIBUTES (decl));
     }
   else if (TYPE_P (*tp))
     *walk_subtrees = 0;
diff --git a/libgomp/testsuite/libgomp.c++/pr96390.C b/libgomp/testsuite/libgomp.c++/pr96390.C
new file mode 100644
index 00000000000..8c770ecb80c
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c++/pr96390.C
@@ -0,0 +1,49 @@
+/* { dg-additional-options "-O0 -fdump-tree-omplower" } */
+/* { dg-xfail-if "PR 97106/PR 97102 - .alias not (yet) supported for nvptx" { offload_target_nvptx } } */
+
+#include <cstdlib>
+#include <type_traits>
+
+template<int Dim> struct V {
+  int version_called;
+
+  template<bool B = (Dim == 0),
+           typename = typename std::enable_if<B>::type>
+  V ()
+  {
+    version_called = 1;
+  }
+
+  template<typename TArg0,
+           typename = typename std::enable_if<(std::is_same<unsigned long,
+                                               typename std::decay<TArg0>::type>::value)>::type>
+  V (TArg0)
+  {
+    version_called = 2;
+  }
+};
+
+template<int Dim> struct S {
+  V<Dim> v;
+};
+
+int
+main ()
+{
+  int version_set[2] = {-1, -1};
+
+#pragma omp target map(from: version_set[0:2])
+  {
+    S<0> s;
+    version_set[0] = s.v.version_called;
+    V<1> v2((unsigned long) 1);
+    version_set[1] = v2.version_called;
+  }
+
+  if (version_set[0] != 1 || version_set[1] != 2)
+    abort ();
+  return 0;
+}
+
+/* "3" for S<0>::S, V<0>::V<>, and V<1>::V<long unsigned int>:  */
+/* { dg-final { scan-tree-dump-times "__attribute__..omp declare target" 3 "omplower" } } */
diff --git a/libgomp/testsuite/libgomp.c-c++-common/pr96390.c b/libgomp/testsuite/libgomp.c-c++-common/pr96390.c
new file mode 100644
index 00000000000..692bd730069
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/pr96390.c
@@ -0,0 +1,26 @@
+/* { dg-additional-options "-O0 -fdump-tree-omplower" } */
+/* { dg-xfail-if "PR 97102/PR 97106 - .alias not (yet) supported for nvptx" { offload_target_nvptx } } */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int foo () { return 42; }
+int bar () __attribute__((alias ("foo")));
+int baz () __attribute__((alias ("bar")));
+
+#ifdef __cplusplus
+}
+#endif
+
+
+int
+main ()
+{
+  int n;
+  #pragma omp target map(from:n)
+    n = baz ();
+  if (n != 42)
+    __builtin_abort ();
+}
+/* { dg-final { scan-tree-dump-times "__attribute__..omp declare target" 1 "omplower" } } */
-- 
2.30.2