[v3] OpenMP: Constructors and destructors for "declare target" static aggregates

Message ID 389518c1-7db2-4eb2-8cba-21a2ae51d2a8@baylibre.com
State New
Headers
Series [v3] OpenMP: Constructors and destructors for "declare target" static aggregates |

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Commit Message

Tobias Burnus Aug. 7, 2024, 12:08 p.m. UTC
  CCed Fortran because of the first item:

This patch now uses (again like in v1) a builtin for 
'omp_is_initial_device'; like in v2, it is compile-time evaluated, but 
this time (new!) it also handled the case that a user wrote that routine.

Note: The omp_… namespace is owned by OpenMP, i.e. if it breaks for a 
user-defined function (when compiled with -fopenmp), it's the fault of 
the user.

Otherwise, it is unchanged except for the following first suggestion. 
And while 'nohost' should be optimized (away on the host), that's 
deferred to a to-be-written follow-up patch.

On Aug 1, 2024, Jakub Jelinek wrote:
> On Tue, Jul 30, 2024 at 10:51:56PM +0200, Tobias Burnus wrote:
>> -  char id[sizeof (SSDF_IDENTIFIER) + 1 /* '\0' */ + 32];
>> +  tree name;
>> ...
> I'd just use a single buffer here,
>    char id[MAX (sizeof (SSDF_IDENTIFIER), sizeof (OMP_SSDF_IDENTIFIER))
> 	  + 1 /* \0 */ + 32];
Done as proposed.
> Given that the Xeon PHI offloading is gone and fork offloading doesn't seem
> to be worked on, my preference would be
> __builtin_omp_is_initial_device () and fold that to 0/1 after IPA, because
> that will actually help user code too.
Done.
> And of course, it would be much better to figure out real nohost fix,
> because if we need to register a constructor which will just do nothing, it
> still wastes runtime.

To be done in a follow-up patch.

Comments, suggestions, concerns?

Tobias

PS: In principle, 'omp_get_num_devices()' would be a candidate for 
'-foffload=disable' (or not configured), but I am not sure how useful it 
is, especially as the decision whether offloading should be done is 
deferred to the link time.

PPS: For OpenACC, there is already an optimization for the similar but 
more complex acc_on_device. But that one doesn't handle Fortran due to 
the different ABI. See https://gcc.gnu.org/PR116269 for details.
  

Comments

Jakub Jelinek Aug. 7, 2024, 12:20 p.m. UTC | #1
On Wed, Aug 07, 2024 at 02:08:42PM +0200, Tobias Burnus wrote:
> On Aug 1, 2024, Jakub Jelinek wrote:
> > On Tue, Jul 30, 2024 at 10:51:56PM +0200, Tobias Burnus wrote:
> > > -  char id[sizeof (SSDF_IDENTIFIER) + 1 /* '\0' */ + 32];
> > > +  tree name;
> > > ...
> > I'd just use a single buffer here,
> >    char id[MAX (sizeof (SSDF_IDENTIFIER), sizeof (OMP_SSDF_IDENTIFIER))
> > 	  + 1 /* \0 */ + 32];
> Done as proposed.
> > Given that the Xeon PHI offloading is gone and fork offloading doesn't seem
> > to be worked on, my preference would be
> > __builtin_omp_is_initial_device () and fold that to 0/1 after IPA, because
> > that will actually help user code too.
> Done.
> > And of course, it would be much better to figure out real nohost fix,
> > because if we need to register a constructor which will just do nothing, it
> > still wastes runtime.
> 
> To be done in a follow-up patch.
> 
> Comments, suggestions, concerns?

As I wrote, I think there should be some option to override the
omp_is_initial_device folding, e.g. for the case where one is compiling some
library code which could be linked either way and so need to avoid folding
omp_is_initial_device because we'll only know at runtime.
But it can certainly wait for incremental change.

> gcc/fortran/ChangeLog:
> 
> 	* f95-lang.cc (gfc_init_builtin_functions): Handle
> 	DEF_GOMP_BUILTIN_COMPILER)

s/)/./

> @@ -5220,6 +5237,9 @@ gimple_fold_builtin (gimple_stmt_iterator *gsi)
>      case BUILT_IN_ACC_ON_DEVICE:
>        return gimple_fold_builtin_acc_on_device (gsi,
>  						gimple_call_arg (stmt, 0));
> +    case BUILT_IN_OMP_IS_INITIAL_DEVICE:
> +	return gimple_fold_builtin_omp_is_initial_device (gsi);

The indentation here looks wrong, case is 4 spaces indented and next line
uses tab, should use 6 spaces.

Maybe would be worth testing that omp_is_initial_device is not treated like
a builtin in C++ in custom namespace, or as a static or non-static member
function, or for C or Fortran as nested function.

Otherwise LGTM.

	Jakub
  
Tobias Burnus Aug. 7, 2024, 3:57 p.m. UTC | #2
Hi Jakub,

for C/C++, -fno-builtin-omp_is_initial_device already disabled the 
expansion.

I added it also for Fortran. Plus added a C and a Fortran testcase for 
the disable flag.

* * *

Wording wise, it failed before for Fortran with:

f951: Warning: command-line option ‘-fno-builtin-omp_is_initial_device’ 
is valid for C/C++/ObjC/ObjC++ but not for Fortran

f951: Warning: command-line option ‘-fbuiltin-omp_is_initial_device’ is 
valid for C/C++/ObjC/ObjC++ but not for Fortran

(The latter is not quite true as all non "no-" ones are rejected for 
C/C++, e.g.: "cc1: error: unrecognized command-line option 
‘-fbuiltin-omp_is_initial_device’").

Now all positive forms fail with: "f951: Error: unrecognized 
command-line option ‘-fbuiltin-omp_is_initial_device’", which should be 
fine and in line with C/C++.

[RFC] The only real question is how to handle unknown -fno-builtin-* 
flags. C/C++ accepts them silently; Fortran did reject them before (see 
above) as unknown flag. And this patch does:

f951: Warning: command-line option ‘-fno-builtin-nothing’ is not valid 
for Fortran

for all but that single supported flag.

* * *

Jakub Jelinek wrote:
> As I wrote, I think there should be some option to override the
> omp_is_initial_device folding, e.g. for the case where one is compiling some
> library code which could be linked either way and so need to avoid folding
> omp_is_initial_device because we'll only know at runtime.

Now done – already there for C/C++, but required the changes for Fortran.

RFC: Should be document this new built-in some where? If so, where? As 
part of the routine description in libgomp.texi? Or in extend.texi (or 
even invoke.texi)?

> Maybe would be worth testing that omp_is_initial_device is not treated like
> a builtin in C++ in custom namespace, or as a static or non-static member
> function, or for C or Fortran as nested function.

For C/C++, it uses the same mechanism (both_p = true) as all other 
builtins; thus, I just hope that it works there.

For Fortran, this plus into gfc_get_extern_function_decl, i.e. that name 
appears as external declaration. While the user could mess around, it 
checks that it is a function and the return type is the expected on 
(i.e. logical). Thus, there shouldn't be any issue with nested functions.

Tobias
  
Jakub Jelinek Aug. 7, 2024, 4:58 p.m. UTC | #3
On Wed, Aug 07, 2024 at 05:57:05PM +0200, Tobias Burnus wrote:
> for C/C++, -fno-builtin-omp_is_initial_device already disabled the
> expansion.

Good idea.

> RFC: Should be document this new built-in some where? If so, where? As part
> of the routine description in libgomp.texi? Or in extend.texi (or even
> invoke.texi)?

I think libgomp.texi in the omp_is_initial_device description, mention
that the compiler folds it by default and that if that is undesirable,
there is this option to use.
> 
> > Maybe would be worth testing that omp_is_initial_device is not treated like
> > a builtin in C++ in custom namespace, or as a static or non-static member
> > function, or for C or Fortran as nested function.
> 
> For C/C++, it uses the same mechanism (both_p = true) as all other builtins;
> thus, I just hope that it works there.

Sure, I expect it to work fine, just thought it wouldn't hurt to double
check that in a test.

> For Fortran, this plus into gfc_get_extern_function_decl, i.e. that name
> appears as external declaration. While the user could mess around, it checks
> that it is a function and the return type is the expected on (i.e. logical).
> Thus, there shouldn't be any issue with nested functions.

And for Fortran I was wondering more whether it would work or not.
Say
program foobar
  if (omp_is_initial_device ()) stop 1
contains
  logical function omp_is_initial_device ()
    omp_is_initial_device = .false.
  end function omp_is_initial_device
end program foobar
or so?

	Jakub
  
Jakub Jelinek Aug. 7, 2024, 4:59 p.m. UTC | #4
On Wed, Aug 07, 2024 at 06:58:23PM +0200, Jakub Jelinek wrote:
> > For Fortran, this plus into gfc_get_extern_function_decl, i.e. that name
> > appears as external declaration. While the user could mess around, it checks
> > that it is a function and the return type is the expected on (i.e. logical).
> > Thus, there shouldn't be any issue with nested functions.
> 
> And for Fortran I was wondering more whether it would work or not.
> Say
> program foobar
>   if (omp_is_initial_device ()) stop 1
> contains
>   logical function omp_is_initial_device ()
>     omp_is_initial_device = .false.
>   end function omp_is_initial_device
> end program foobar
> or so?

Guess a module function would be interesting as well.

	Jakub
  

Patch

OpenMP: Constructors and destructors for "declare target" static aggregates

This commit also compile-time expands (__builtin_)omp_is_initial_device for
both Fortran and C/C++. But the main change is:

This commit adds support for running constructors and destructors for
static (file-scope) aggregates for C++ objects which are marked with
"declare target" directives on OpenMP offload targets.

Before this commit, space is allocated on the target for such aggregates,
but nothing ever constructs them properly, so they end up zero-initialised.

(See the new test static-aggr-constructor-destructor-3.C for a reason
why running constructors on the target is preferable to e.g. constructing
on the host and then copying the resulting object to the target.)

2024-08-07  Julian Brown  <julian@codesourcery.com>
	    Tobias Burnus  <tobias@baylibre.com>

gcc/ChangeLog:

	* builtins.def (DEF_GOMP_BUILTIN_COMPILER): Define
	DEF_GOMP_BUILTIN_COMPILER to handle the non-prefix version.
	* gimple-fold.cc (gimple_fold_builtin_omp_is_initial_device): New.
	(gimple_fold_builtin): Call it.
	* omp-builtins.def (BUILT_IN_OMP_IS_INITIAL_DEVICE): Define.
	* tree.cc (get_file_function_name): Support names for on-target
	constructor/destructor functions.

gcc/cp/
	* decl2.cc (tree-inline.h): Include.
	(static_init_fini_fns): Bump to four entries. Update comment.
	(start_objects, start_partial_init_fini_fn): Add 'omp_target'
	parameter. Support "declare target" decls. Update forward declaration.
	(emit_partial_init_fini_fn): Add 'host_fn' parameter. Return tree for
	the created function. Support "declare target".
	(OMP_SSDF_IDENTIFIER): New macro.
	(partition_vars_for_init_fini): Support partitioning "declare target"
	variables also.
	(generate_ctor_or_dtor_function): Add 'omp_target' parameter. Support
	"declare target" decls.
	(c_parse_final_cleanups): Support constructors/destructors on OpenMP
	offload targets.

gcc/fortran/ChangeLog:

	* f95-lang.cc (gfc_init_builtin_functions): Handle
	DEF_GOMP_BUILTIN_COMPILER)
	* trans-decl.cc (gfc_get_extern_function_decl): Add code to use
	DEF_GOMP_BUILTIN_COMPILER for 'omp_is_initial_device'.

libgomp/ChangeLog:

	* testsuite/libgomp.c++/static-aggr-constructor-destructor-1.C: New test.
	* testsuite/libgomp.c++/static-aggr-constructor-destructor-2.C: New test.
	* testsuite/libgomp.c++/static-aggr-constructor-destructor-3.C: New test.
	* testsuite/libgomp.c-c++-common/target-is-initial-host.c: New test.
	* testsuite/libgomp.fortran/target-is-initial-host.f: New test.
	* testsuite/libgomp.fortran/target-is-initial-host.f90: New test.

Co-authored-by: Tobias Burnus <tobias@baylibre.com>

 gcc/builtins.def                                   |   4 +
 gcc/cp/decl2.cc                                    | 229 +++++++++++++++++----
 gcc/fortran/f95-lang.cc                            |   9 +
 gcc/fortran/trans-decl.cc                          |   8 +
 gcc/gimple-fold.cc                                 |  20 ++
 gcc/omp-builtins.def                               |   4 +
 gcc/tree.cc                                        |   6 +-
 .../static-aggr-constructor-destructor-1.C         |  72 +++++++
 .../static-aggr-constructor-destructor-2.C         |  50 +++++
 .../static-aggr-constructor-destructor-3.C         |  36 ++++
 .../libgomp.c-c++-common/target-is-initial-host.c  |  42 ++++
 .../libgomp.fortran/target-is-initial-host.f       |  35 ++++
 .../libgomp.fortran/target-is-initial-host.f90     |  35 ++++
 13 files changed, 510 insertions(+), 40 deletions(-)

diff --git a/gcc/builtins.def b/gcc/builtins.def
index f6f3e104f6a..a3921aa6856 100644
--- a/gcc/builtins.def
+++ b/gcc/builtins.def
@@ -224,6 +224,10 @@  along with GCC; see the file COPYING3.  If not see
 	       (flag_openacc \
 		|| flag_openmp \
 		|| flag_tree_parallelize_loops > 1))
+#undef DEF_GOMP_BUILTIN_COMPILER
+#define DEF_GOMP_BUILTIN_COMPILER(ENUM, NAME, TYPE, ATTRS) \
+  DEF_BUILTIN (ENUM, "__builtin_" NAME, BUILT_IN_NORMAL, TYPE, TYPE,    \
+               flag_openmp, true, true, ATTRS, false, flag_openmp)
 
 /* Builtin used by the implementation of GNU TM.  These
    functions are mapped to the actual implementation of the STM library. */
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index 695d5f8d790..e9ae979896c 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -50,6 +50,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "asan.h"
 #include "optabs-query.h"
 #include "omp-general.h"
+#include "tree-inline.h"
 #include "escaped_string.h"
 
 /* Id for dumping the raw trees.  */
@@ -57,14 +58,15 @@  int raw_dump_id;
  
 extern cpp_reader *parse_in;
 
-static tree start_objects (bool, unsigned, bool);
+static tree start_objects (bool, unsigned, bool, bool);
 static tree finish_objects (bool, unsigned, tree, bool = true);
-static tree start_partial_init_fini_fn (bool, unsigned, unsigned);
+static tree start_partial_init_fini_fn (bool, unsigned, unsigned, bool);
 static void finish_partial_init_fini_fn (tree);
-static void emit_partial_init_fini_fn (bool, unsigned, tree,
-				       unsigned, location_t);
+static tree emit_partial_init_fini_fn (bool, unsigned, tree,
+				       unsigned, location_t, tree);
 static void one_static_initialization_or_destruction (bool, tree, tree);
-static void generate_ctor_or_dtor_function (bool, unsigned, tree, location_t);
+static void generate_ctor_or_dtor_function (bool, unsigned, tree, location_t,
+					    bool);
 static tree prune_vars_needing_no_initialization (tree *);
 static void write_out_vars (tree);
 static void import_export_class (tree);
@@ -166,9 +168,10 @@  struct priority_map_traits
 typedef hash_map<unsigned/*Priority*/, tree/*List*/,
 		 priority_map_traits> priority_map_t;
 
-/* A pair of such hash tables, indexed by initp -- one for fini and
-   one for init.  The fini table is only ever used when !cxa_atexit.  */
-static GTY(()) priority_map_t *static_init_fini_fns[2];
+/* Two pairs of such hash tables, for the host and an OpenMP offload device.
+   Each pair has one priority map for fini and one for init.  The fini tables
+   are only ever used when !cxa_atexit.  */
+static GTY(()) priority_map_t *static_init_fini_fns[4];
 
 /* Nonzero if we're done parsing and into end-of-file activities.
    2 if all templates have been instantiated.
@@ -4048,7 +4051,8 @@  generate_tls_wrapper (tree fn)
 /* Start a global constructor or destructor function.  */
 
 static tree
-start_objects (bool initp, unsigned priority, bool has_body)
+start_objects (bool initp, unsigned priority, bool has_body,
+	       bool omp_target = false)
 {
   bool default_init = initp && priority == DEFAULT_INIT_PRIORITY;
   bool is_module_init = default_init && module_global_init_needed ();
@@ -4062,7 +4066,15 @@  start_objects (bool initp, unsigned priority, bool has_body)
 
       /* We use `I' to indicate initialization and `D' to indicate
 	 destruction.  */
-      unsigned len = sprintf (type, "sub_%c", initp ? 'I' : 'D');
+      unsigned len;
+      if (omp_target)
+	/* Use "off_" signifying "offload" here.  The name must be distinct
+	   from the non-offload case.  The format of the name is scanned in
+	   tree.cc/get_file_function_name, so stick to the same length for
+	   both name variants.  */
+	len = sprintf (type, "off_%c", initp ? 'I' : 'D');
+      else
+	len = sprintf (type, "sub_%c", initp ? 'I' : 'D');
       if (priority != DEFAULT_INIT_PRIORITY)
 	{
 	  char joiner = '_';
@@ -4077,6 +4089,17 @@  start_objects (bool initp, unsigned priority, bool has_body)
 
   tree fntype =	build_function_type (void_type_node, void_list_node);
   tree fndecl = build_lang_decl (FUNCTION_DECL, name, fntype);
+
+  if (omp_target)
+    {
+      DECL_ATTRIBUTES (fndecl)
+	= tree_cons (get_identifier ("omp declare target"), NULL_TREE,
+		     DECL_ATTRIBUTES (fndecl));
+      DECL_ATTRIBUTES (fndecl)
+	= tree_cons (get_identifier ("omp declare target nohost"), NULL_TREE,
+		     DECL_ATTRIBUTES (fndecl));
+    }
+
   DECL_CONTEXT (fndecl) = FROB_CONTEXT (global_namespace);
   if (is_module_init)
     {
@@ -4161,34 +4184,53 @@  finish_objects (bool initp, unsigned priority, tree body, bool startp)
 /* The name of the function we create to handle initializations and
    destructions for objects with static storage duration.  */
 #define SSDF_IDENTIFIER "__static_initialization_and_destruction"
+#define OMP_SSDF_IDENTIFIER "__omp_target_static_init_and_destruction"
 
 /* Begins the generation of the function that will handle all
    initialization or destruction of objects with static storage
    duration at PRIORITY.
 
-   It is assumed that this function will only be called once.  */
+   It is assumed that this function will be called once for the host, and once
+   for an OpenMP offload target.  */
 
 static tree
-start_partial_init_fini_fn (bool initp, unsigned priority, unsigned count)
+start_partial_init_fini_fn (bool initp, unsigned priority, unsigned count,
+			    bool omp_target)
 {
-  char id[sizeof (SSDF_IDENTIFIER) + 1 /* '\0' */ + 32];
+  char id[MAX (sizeof (SSDF_IDENTIFIER), sizeof (OMP_SSDF_IDENTIFIER))
+	  + 1 /* \0 */ + 32];
+  tree name;
 
   /* Create the identifier for this function.  It will be of the form
-     SSDF_IDENTIFIER_<number>.  */
-  sprintf (id, "%s_%u", SSDF_IDENTIFIER, count);
-
+     SSDF_IDENTIFIER_<number> if not omp_target and otherwise
+     OMP_SSDF_IDENTIFIER_<number>.  */
+  sprintf (id, "%s_%u", omp_target ? OMP_SSDF_IDENTIFIER : SSDF_IDENTIFIER,
+	   count);
+  name = get_identifier (id);
   tree type = build_function_type (void_type_node, void_list_node);
 
   /* Create the FUNCTION_DECL itself.  */
-  tree fn = build_lang_decl (FUNCTION_DECL, get_identifier (id), type);
+  tree fn = build_lang_decl (FUNCTION_DECL, name, type);
   TREE_PUBLIC (fn) = 0;
   DECL_ARTIFICIAL (fn) = 1;
 
+  if (omp_target)
+    {
+      DECL_ATTRIBUTES (fn)
+	= tree_cons (get_identifier ("omp declare target"), NULL_TREE,
+		     DECL_ATTRIBUTES (fn));
+      DECL_ATTRIBUTES (fn)
+	= tree_cons (get_identifier ("omp declare target nohost"), NULL_TREE,
+		     DECL_ATTRIBUTES (fn));
+    }
+
+  int idx = initp + 2 * omp_target;
+
   /* Put this function in the list of functions to be called from the
      static constructors and destructors.  */
-  if (!static_init_fini_fns[initp])
-    static_init_fini_fns[initp] = priority_map_t::create_ggc ();
-  auto &slot = static_init_fini_fns[initp]->get_or_insert (priority);
+  if (!static_init_fini_fns[idx])
+    static_init_fini_fns[idx] = priority_map_t::create_ggc ();
+  auto &slot = static_init_fini_fns[idx]->get_or_insert (priority);
   slot = tree_cons (fn, NULL_TREE, slot);
 
   /* Put the function in the global scope.  */
@@ -4384,22 +4426,74 @@  one_static_initialization_or_destruction (bool initp, tree decl, tree init)
    a TREE_LIST of VAR_DECL with static storage duration.
    Whether initialization or destruction is performed is specified by INITP.  */
 
-static void
+static tree
 emit_partial_init_fini_fn (bool initp, unsigned priority, tree vars,
-			   unsigned counter, location_t locus)
+			   unsigned counter, location_t locus, tree host_fn)
 {
   input_location = locus;
-  tree body = start_partial_init_fini_fn (initp, priority, counter);
+  bool omp_target = (host_fn != NULL_TREE);
+  tree body = start_partial_init_fini_fn (initp, priority, counter, omp_target);
+  tree fndecl = current_function_decl;
+
+  tree nonhost_if_stmt = NULL_TREE;
+  if (omp_target)
+    {
+      nonhost_if_stmt = begin_if_stmt ();
+      /* We add an "omp declare target nohost" attribute, but (for
+	 now) we still get a copy of the constructor/destructor on
+	 the host.  Make sure it does nothing unless we're on the
+	 target device.  */
+      tree fn = builtin_decl_explicit (BUILT_IN_OMP_IS_INITIAL_DEVICE);
+      tree initial_dev = build_call_expr (fn, 0);
+      tree target_dev_p
+	= cp_build_binary_op (input_location, NE_EXPR, initial_dev,
+			      integer_one_node, tf_warning_or_error);
+      finish_if_stmt_cond (target_dev_p, nonhost_if_stmt);
+    }
 
   for (tree node = vars; node; node = TREE_CHAIN (node))
-    /* Do one initialization or destruction.  */
-    one_static_initialization_or_destruction (initp, TREE_VALUE (node),
-					      TREE_PURPOSE (node));
+    {
+      tree decl = TREE_VALUE (node);
+      tree init = TREE_PURPOSE (node);
+	/* We will emit 'init' twice, and it is modified in-place during
+	   gimplification.  Make a copy here.  */
+      if (omp_target)
+	{
+	  /* We've already emitted INIT in the host version of the ctor/dtor
+	     function.  We need to deep-copy it (including new versions of
+	     local variables introduced, etc.) for use in the target
+	     ctor/dtor function.  */
+	  copy_body_data id;
+	  hash_map<tree, tree> decl_map;
+	  memset (&id, 0, sizeof (id));
+	  id.src_fn = host_fn;
+	  id.dst_fn = current_function_decl;
+	  id.src_cfun = DECL_STRUCT_FUNCTION (id.src_fn);
+	  id.decl_map = &decl_map;
+	  id.copy_decl = copy_decl_no_change;
+	  id.transform_call_graph_edges = CB_CGE_DUPLICATE;
+	  id.transform_new_cfg = true;
+	  id.transform_return_to_modify = false;
+	  id.eh_lp_nr = 0;
+	  walk_tree (&init, copy_tree_body_r, &id, NULL);
+	}
+      /* Do one initialization or destruction.  */
+      one_static_initialization_or_destruction (initp, decl, init);
+    }
+
+  if (omp_target)
+    {
+      /* Finish up nonhost if-stmt body.  */
+      finish_then_clause (nonhost_if_stmt);
+      finish_if_stmt (nonhost_if_stmt);
+    }
 
   /* Finish up the static storage duration function for this
      round.  */
   input_location = locus;
   finish_partial_init_fini_fn (body);
+
+  return fndecl;
 }
 
 /* VARS is a list of variables with static storage duration which may
@@ -4462,7 +4556,7 @@  prune_vars_needing_no_initialization (tree *vars)
    This reverses the variable ordering.  */
 
 void
-partition_vars_for_init_fini (tree var_list, priority_map_t *(&parts)[2])
+partition_vars_for_init_fini (tree var_list, priority_map_t *(&parts)[4])
 {
   for (auto node = var_list; node; node = TREE_CHAIN (node))
     {
@@ -4488,6 +4582,30 @@  partition_vars_for_init_fini (tree var_list, priority_map_t *(&parts)[2])
 	  auto &slot = parts[false]->get_or_insert (priority);
 	  slot = tree_cons (NULL_TREE, decl, slot);
 	}
+
+      if (flag_openmp
+	   && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
+	{
+	  priority_map_t **omp_parts = parts + 2;
+
+	  if (init || (flag_use_cxa_atexit && has_cleanup))
+	    {
+	      // Add to initialization list.
+	      if (!omp_parts[true])
+		omp_parts[true] = priority_map_t::create_ggc ();
+	      auto &slot = omp_parts[true]->get_or_insert (priority);
+	      slot = tree_cons (init, decl, slot);
+	    }
+
+	  if (!flag_use_cxa_atexit && has_cleanup)
+	    {
+	      // Add to finalization list.
+	      if (!omp_parts[false])
+		omp_parts[false] = priority_map_t::create_ggc ();
+	      auto &slot = omp_parts[false]->get_or_insert (priority);
+	      slot = tree_cons (NULL_TREE, decl, slot);
+	    }
+	}
     }
 }
 
@@ -4515,10 +4633,10 @@  write_out_vars (tree vars)
 
 static void
 generate_ctor_or_dtor_function (bool initp, unsigned priority,
-				tree fns, location_t locus)
+				tree fns, location_t locus, bool omp_target)
 {
   input_location = locus;
-  tree body = start_objects (initp, priority, bool (fns));
+  tree body = start_objects (initp, priority, bool (fns), omp_target);
 
   if (fns)
     {
@@ -5190,7 +5308,7 @@  c_parse_final_cleanups (void)
   auto_vec<tree> consteval_vtables;
 
   int retries = 0;
-  unsigned ssdf_count = 0;
+  unsigned ssdf_count = 0, omp_ssdf_count = 0;
   for (bool reconsider = true; reconsider; retries++)
     {
       reconsider = false;
@@ -5253,8 +5371,9 @@  c_parse_final_cleanups (void)
 	  write_out_vars (vars);
 
 	  function_depth++; // Disable GC
-	  priority_map_t *parts[2] = {nullptr, nullptr};
+	  priority_map_t *parts[4] = {nullptr, nullptr, nullptr, nullptr};
 	  partition_vars_for_init_fini (vars, parts);
+	  tree host_init_fini[2] = { NULL_TREE, NULL_TREE };
 
 	  for (unsigned initp = 2; initp--;)
 	    if (parts[initp])
@@ -5265,10 +5384,32 @@  c_parse_final_cleanups (void)
 		    // Partitioning kept the vars in reverse order.
 		    // We only want that for dtors.
 		    list = nreverse (list);
-		  emit_partial_init_fini_fn (initp, iter.first, list,
-					     ssdf_count++,
-					     locus_at_end_of_parsing);
+		  host_init_fini[initp]
+		    = emit_partial_init_fini_fn (initp, iter.first, list,
+						 ssdf_count++,
+						 locus_at_end_of_parsing,
+						 NULL_TREE);
 		}
+
+	  if (flag_openmp)
+	    {
+	      priority_map_t **omp_parts = parts + 2;
+	      for (unsigned initp = 2; initp--;)
+		if (omp_parts[initp])
+		  for (auto iter : *omp_parts[initp])
+		    {
+		      auto list = iter.second;
+		      if (initp)
+			// Partitioning kept the vars in reverse order.
+			// We only want that for dtors.
+			list = nreverse (list);
+		      emit_partial_init_fini_fn (initp, iter.first, list,
+						 omp_ssdf_count++,
+						 locus_at_end_of_parsing,
+						 host_init_fini[initp]);
+		  }
+	    }
+
 	  function_depth--; // Re-enable GC
 
 	  /* All those initializations and finalizations might cause
@@ -5439,6 +5580,10 @@  c_parse_final_cleanups (void)
     for (auto iter : *static_init_fini_fns[true])
       iter.second = nreverse (iter.second);
 
+  if (flag_openmp && static_init_fini_fns[2 + true])
+    for (auto iter : *static_init_fini_fns[2 + true])
+      iter.second = nreverse (iter.second);
+
   /* Now we've instantiated all templates.  Now we can escalate the functions
      we squirreled away earlier.  */
   process_and_check_pending_immediate_escalating_fns ();
@@ -5457,7 +5602,7 @@  c_parse_final_cleanups (void)
     {
       input_location = locus_at_end_of_parsing;
       tree body = start_partial_init_fini_fn (true, DEFAULT_INIT_PRIORITY,
-					      ssdf_count++);
+					      ssdf_count++, false);
       /* For Objective-C++, we may need to initialize metadata found
 	 in this module.  This must be done _before_ any other static
 	 initializations.  */
@@ -5476,18 +5621,26 @@  c_parse_final_cleanups (void)
 	static_init_fini_fns[true] = priority_map_t::create_ggc ();
       if (static_init_fini_fns[true]->get_or_insert (DEFAULT_INIT_PRIORITY))
 	has_module_inits = true;
+
+      if (flag_openmp)
+	{
+	  if (!static_init_fini_fns[2 + true])
+	    static_init_fini_fns[2 + true] = priority_map_t::create_ggc ();
+	  static_init_fini_fns[2 + true]->get_or_insert (DEFAULT_INIT_PRIORITY);
+	}
     }
 
   /* Generate initialization and destruction functions for all
      priorities for which they are required.  They have C-language
      linkage.  */
   push_lang_context (lang_name_c);
-  for (unsigned initp = 2; initp--;)
+  for (unsigned initp = 4; initp--;)
     if (static_init_fini_fns[initp])
       {
 	for (auto iter : *static_init_fini_fns[initp])
-	  generate_ctor_or_dtor_function (initp, iter.first, iter.second,
-					  locus_at_end_of_parsing);
+	  generate_ctor_or_dtor_function (initp & 1, iter.first, iter.second,
+					  locus_at_end_of_parsing,
+					  (initp & 2) != 0);
 	static_init_fini_fns[initp] = nullptr;
       }
   pop_lang_context ();
diff --git a/gcc/fortran/f95-lang.cc b/gcc/fortran/f95-lang.cc
index 67fda27aa3e..770f31b221d 100644
--- a/gcc/fortran/f95-lang.cc
+++ b/gcc/fortran/f95-lang.cc
@@ -1271,10 +1271,13 @@  gfc_init_builtin_functions (void)
 			  attr);
 #undef DEF_GOMP_BUILTIN
 #define DEF_GOMP_BUILTIN(code, name, type, attr) /* ignore */
+#undef DEF_GOMP_BUILTIN_COMPILER
+#define DEF_GOMP_BUILTIN_COMPILER(code, name, type, attr) /* ignore */
 #include "../omp-builtins.def"
 #undef DEF_GOACC_BUILTIN
 #undef DEF_GOACC_BUILTIN_COMPILER
 #undef DEF_GOMP_BUILTIN
+#undef DEF_GOMP_BUILTIN_COMPILER
     }
 
   if (flag_openmp || flag_openmp_simd || flag_tree_parallelize_loops)
@@ -1287,10 +1290,16 @@  gfc_init_builtin_functions (void)
 #define DEF_GOMP_BUILTIN(code, name, type, attr) \
       gfc_define_builtin ("__builtin_" name, builtin_types[type], \
 			  code, name, attr);
+#undef DEF_GOMP_BUILTIN_COMPILER
+#define DEF_GOMP_BUILTIN_COMPILER(code, name, type, attr) \
+      if (flag_openmp) \
+	gfc_define_builtin ("__builtin_" name, builtin_types[type], \
+			      code, name, attr);
 #include "../omp-builtins.def"
 #undef DEF_GOACC_BUILTIN
 #undef DEF_GOACC_BUILTIN_COMPILER
 #undef DEF_GOMP_BUILTIN
+#undef DEF_GOMP_BUILTIN_COMPILER
       tree gomp_alloc = builtin_decl_explicit (BUILT_IN_GOMP_ALLOC);
       tree two = build_int_cst (integer_type_node, 2);
       DECL_ATTRIBUTES (gomp_alloc)
diff --git a/gcc/fortran/trans-decl.cc b/gcc/fortran/trans-decl.cc
index 0fdc41b1784..b854b664305 100644
--- a/gcc/fortran/trans-decl.cc
+++ b/gcc/fortran/trans-decl.cc
@@ -2214,6 +2214,14 @@  gfc_get_extern_function_decl (gfc_symbol * sym, gfc_actual_arglist *actual_args,
      to know that.  */
   gcc_assert (!(sym->attr.entry || sym->attr.entry_master));
 
+  if (flag_openmp && sym->attr.function && sym->ts.type == BT_LOGICAL
+      && !strcmp (sym->name, "omp_is_initial_device"))
+    {
+      sym->backend_decl
+	= builtin_decl_explicit (BUILT_IN_OMP_IS_INITIAL_DEVICE);
+      return sym->backend_decl;
+    }
+
   if (sym->attr.proc_pointer)
     return get_proc_pointer_decl (sym);
 
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index c20102f73f5..faca2054c7e 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -4043,6 +4043,23 @@  gimple_fold_builtin_strlen (gimple_stmt_iterator *gsi)
   return false;
 }
 
+static bool
+gimple_fold_builtin_omp_is_initial_device (gimple_stmt_iterator *gsi)
+{
+#if ACCEL_COMPILER
+  replace_call_with_value (gsi, integer_zero_node);
+  return true;
+#else
+  if (!ENABLE_OFFLOADING || symtab->state == EXPANSION)
+    {
+      replace_call_with_value (gsi, integer_one_node);
+      return true;
+    }
+#endif
+  return false;
+}
+
+
 /* Fold a call to __builtin_acc_on_device.  */
 
 static bool
@@ -5220,6 +5237,9 @@  gimple_fold_builtin (gimple_stmt_iterator *gsi)
     case BUILT_IN_ACC_ON_DEVICE:
       return gimple_fold_builtin_acc_on_device (gsi,
 						gimple_call_arg (stmt, 0));
+    case BUILT_IN_OMP_IS_INITIAL_DEVICE:
+	return gimple_fold_builtin_omp_is_initial_device (gsi);
+
     case BUILT_IN_REALLOC:
       return gimple_fold_builtin_realloc (gsi);
 
diff --git a/gcc/omp-builtins.def b/gcc/omp-builtins.def
index 044d5d087b6..7b49ef1c0e5 100644
--- a/gcc/omp-builtins.def
+++ b/gcc/omp-builtins.def
@@ -23,6 +23,7 @@  along with GCC; see the file COPYING3.  If not see
      DEF_GOACC_BUILTIN (ENUM, NAME, TYPE, ATTRS)
      DEF_GOACC_BUILTIN_COMPILER (ENUM, NAME, TYPE, ATTRS)
      DEF_GOMP_BUILTIN (ENUM, NAME, TYPE, ATTRS)
+     DEF_GOMP_BUILTIN_COMPILER (ENUM, NAME, TYPE, ATTRS)
 
    See builtins.def for details.  */
 
@@ -68,6 +69,9 @@  DEF_GOACC_BUILTIN_ONLY (BUILT_IN_GOACC_SINGLE_COPY_START, "GOACC_single_copy_sta
 DEF_GOACC_BUILTIN_ONLY (BUILT_IN_GOACC_SINGLE_COPY_END, "GOACC_single_copy_end",
 			BT_FN_VOID_PTR, ATTR_NOTHROW_LEAF_LIST)
 
+DEF_GOMP_BUILTIN_COMPILER (BUILT_IN_OMP_IS_INITIAL_DEVICE,
+			   "omp_is_initial_device", BT_FN_INT,
+			   ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GOMP_BUILTIN (BUILT_IN_OMP_GET_THREAD_NUM, "omp_get_thread_num",
 		  BT_FN_INT, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GOMP_BUILTIN (BUILT_IN_OMP_GET_NUM_THREADS, "omp_get_num_threads",
diff --git a/gcc/tree.cc b/gcc/tree.cc
index a2d431662bd..17a5cea7c25 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -8908,9 +8908,11 @@  get_file_function_name (const char *type)
      will be local to this file and the name is only necessary for
      debugging purposes. 
      We also assign sub_I and sub_D sufixes to constructors called from
-     the global static constructors.  These are always local.  */
+     the global static constructors.  These are always local.
+     OpenMP "declare target" offloaded constructors/destructors use "off_I" and
+     "off_D" for the same purpose.  */
   else if (((type[0] == 'I' || type[0] == 'D') && targetm.have_ctors_dtors)
-	   || (startswith (type, "sub_")
+	   || ((startswith (type, "sub_") || startswith (type, "off_"))
 	       && (type[4] == 'I' || type[4] == 'D')))
     {
       const char *file = main_input_filename;
diff --git a/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-1.C b/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-1.C
new file mode 100644
index 00000000000..403a071c0c0
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-1.C
@@ -0,0 +1,72 @@ 
+// { dg-do run }
+// { dg-additional-options "-fdump-tree-gimple -fdump-tree-optimized" }
+// { dg-additional-options -foffload-options=-fdump-tree-optimized { target { offload_device_nvptx || offload_target_amdgcn } } }
+
+// { dg-final { scan-tree-dump-times "omp_is_initial_device" 1 "gimple" } }
+// { dg-final { scan-tree-dump-times "_GLOBAL__off_I_v1" 1 "gimple" } }
+// { dg-final { scan-tree-dump-times "__omp_target_static_init_and_destruction" 2 "gimple" } }
+// { dg-final { scan-tree-dump-times "__attribute__\\(\\(\[^\n\r]*omp declare target nohost" 2 "gimple" } }
+
+// { dg-final { scan-tree-dump-not "omp_is_initial_device" "optimized" } }
+// { dg-final { scan-tree-dump-not "__omp_target_static_init_and_destruction" "optimized" } }
+// FIXME: should be '-not' not '-times' 1:
+// { dg-final { scan-tree-dump-times "void _GLOBAL__off_I_v1" 1 "optimized" } }
+// { dg-final { scan-tree-dump-times "__attribute__\\(\\(\[^\n\r]*omp declare target nohost" 1 "optimized" } }
+
+// { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump-not "omp_initial_device;" "optimized" { target offload_target_amdgcn } } }
+// { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump "v1\\._x = 5;" "optimized" { target offload_target_amdgcn } } }
+// { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump-not "omp_initial_device;" "optimized" { target offload_target_nvptx } } }
+// { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump "v1\\._x = 5;" "optimized" { target offload_target_nvptx } } }
+
+#include <cassert>
+#include <omp.h>
+
+#pragma omp declare target
+
+struct str {
+  str(int x) : _x(x) { }
+  int add(str o) { return _x + o._x; }
+  int _x;
+} v1(5);
+
+#pragma omp end declare target
+
+void check_host()
+{
+  assert (v1._x == 5);
+}
+
+void check_devs()
+{
+  for (int dev = omp_initial_device; dev <= omp_get_num_devices(); dev++)
+    {
+      int res = 99, dev_num = 98;
+      #pragma omp target map(from: res, dev_num) device(dev)
+	{
+	  res = v1._x;
+	  dev_num = omp_get_device_num();
+	}
+      assert (res == 5);
+      if (dev == omp_initial_device)
+	assert (dev_num == omp_get_num_devices());
+      else
+	assert (dev_num == dev);
+    }
+}
+
+int main()
+{
+  int res = -1;
+  str v2(2);
+
+#pragma omp target map(from:res)
+  {
+    res = v1.add(v2);
+  }
+
+  assert (res == 7);
+  check_host();
+  check_devs();
+
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-2.C b/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-2.C
new file mode 100644
index 00000000000..6dd4260a522
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-2.C
@@ -0,0 +1,50 @@ 
+// { dg-do run }
+// { dg-additional-options "-fdump-tree-gimple -fdump-tree-optimized" }
+// { dg-additional-options -foffload-options=-fdump-tree-optimized { target { offload_device_nvptx || offload_target_amdgcn } } }
+
+// { dg-final { scan-tree-dump-times "omp_is_initial_device" 1 "gimple" } }
+// { dg-final { scan-tree-dump-times "_GLOBAL__off_I_v1" 1 "gimple" } }
+// { dg-final { scan-tree-dump-times "__omp_target_static_init_and_destruction" 2 "gimple" } }
+// { dg-final { scan-tree-dump-times "__attribute__\\(\\(\[^\n\r]*omp declare target nohost" 2 "gimple" } }
+
+// { dg-final { scan-tree-dump-not "omp_is_initial_device" "optimized" } }
+// { dg-final { scan-tree-dump-not "__omp_target_static_init_and_destruction" "optimized" } }
+// FIXME: should be '-not' not '-times' 1:
+// { dg-final { scan-tree-dump-times "void _GLOBAL__off_I_" 1 "optimized" } }
+// { dg-final { scan-tree-dump-times "__attribute__\\(\\(\[^\n\r]*omp declare target nohost" 1 "optimized" } }
+
+// { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump-not "omp_initial_device;" "optimized" { target offload_target_amdgcn } } }
+// { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump "v1\\._x = 5;" "optimized" { target offload_target_amdgcn } } }
+// { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump-not "omp_initial_device;" "optimized" { target offload_target_nvptx } } }
+// { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump "v1\\._x = 5;" "optimized" { target offload_target_nvptx } } }
+
+
+#include <cassert>
+
+#pragma omp declare target
+
+template<typename T>
+struct str {
+  str(T x) : _x(x) { }
+  T add(str o) { return _x + o._x; }
+  T _x;
+};
+
+str<long> v1(5);
+
+#pragma omp end declare target
+
+int main()
+{
+  long res = -1;
+  str<long> v2(2);
+
+#pragma omp target map(from:res)
+  {
+    res = v1.add(v2);
+  }
+
+  assert (res == 7);
+
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-3.C b/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-3.C
new file mode 100644
index 00000000000..8d4aff21cd7
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c++/static-aggr-constructor-destructor-3.C
@@ -0,0 +1,36 @@ 
+// { dg-do run }
+
+#include <cassert>
+
+#pragma omp declare target
+
+struct item {
+  item(item *p, int v) : prev(p), val(v) { }
+  int get() { return prev ? prev->get() * val : val; }
+  item *prev;
+  int val;
+};
+
+/* This case demonstrates why constructing on the host and then copying to
+   the target would be less desirable.  With on-target construction, "prev"
+   for each 'item' will be a device pointer, not a host pointer.  */
+item hubert1(nullptr, 3);
+item hubert2(&hubert1, 5);
+item hubert3(&hubert2, 7);
+item hubert4(&hubert3, 11);
+
+#pragma omp end declare target
+
+int main()
+{
+  int res = -1;
+
+#pragma omp target map(from:res)
+  {
+    res = hubert4.get ();
+  }
+
+  assert (res == 1155);
+
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.c-c++-common/target-is-initial-host.c b/libgomp/testsuite/libgomp.c-c++-common/target-is-initial-host.c
new file mode 100644
index 00000000000..423727ce55f
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/target-is-initial-host.c
@@ -0,0 +1,42 @@ 
+/* { dg-do run } */
+
+/* Check whether 'omp_is_initial_device()' is properly compile-time optimized. */
+
+/* { dg-additional-options "-fdump-tree-gimple -fdump-tree-optimized" }  */
+/* { dg-additional-options -foffload-options=-fdump-tree-optimized { target { offload_device_nvptx || offload_target_amdgcn } } }  */
+
+/* { dg-final { scan-tree-dump-times "omp_is_initial_device" 1 "gimple" } }  */
+
+/* { dg-final { scan-tree-dump-not "omp_is_initial_device" "optimized" } }  */
+
+/* { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump-not "omp_is_initial_device" "optimized" { target offload_target_amdgcn } } }  */
+/* { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump-not "omp_is_initial_device" "optimized" { target offload_target_nvptx } } }  */
+
+
+#include <omp.h>
+
+int
+main ()
+{
+  int is_initial, dev_num, initial;
+  initial = omp_get_initial_device();
+  for (int dev = omp_initial_device; dev <= omp_get_num_devices(); dev++)
+    {
+      is_initial = dev_num = 99;
+      #pragma omp target map(from: is_initial, dev_num) device(dev)
+        {
+          is_initial = omp_is_initial_device ();
+          dev_num = omp_get_device_num ();
+        }
+      if (dev == omp_initial_device || dev == initial)
+	{
+	  if (dev_num != initial || is_initial != 1)
+	    __builtin_abort ();
+	}
+      else
+	{
+	  if (dev_num != dev || is_initial != 0)
+	    __builtin_abort ();
+	}
+    }
+}
diff --git a/libgomp/testsuite/libgomp.fortran/target-is-initial-host.f b/libgomp/testsuite/libgomp.fortran/target-is-initial-host.f
new file mode 100644
index 00000000000..fec4a3f1c1c
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/target-is-initial-host.f
@@ -0,0 +1,35 @@ 
+! Check whether 'omp_is_initial_device()' is properly compile-time optimized. */
+
+! { dg-additional-options "-fdump-tree-gimple -fdump-tree-optimized" }
+! { dg-additional-options -foffload-options=-fdump-tree-optimized { target { offload_device_nvptx || offload_target_amdgcn } } }
+
+! { dg-final { scan-tree-dump-times "omp_is_initial_device" 1 "gimple" } }
+
+! { dg-final { scan-tree-dump-not "omp_is_initial_device" "optimized" } }
+
+! { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump-not "omp_is_initial_device" "optimized" { target offload_target_amdgcn } } }
+! { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump-not "omp_is_initial_device" "optimized" { target offload_target_nvptx } } }
+
+
+      program main
+      implicit none (type, external)
+      include "omp_lib.h" 
+      integer :: dev_num, initial, dev
+      logical :: is_initial
+
+      initial = omp_get_initial_device()
+      do dev = omp_initial_device, omp_get_num_devices()
+        dev_num = 99
+!$omp target map(from: is_initial, dev_num) device(dev)
+          is_initial = omp_is_initial_device ()
+          dev_num = omp_get_device_num ()
+!$omp end target
+        if (dev == omp_initial_device .or. dev == initial) then
+          if (dev_num /= initial .or. .not. is_initial)                         &
+     &      stop 1
+        else
+          if (dev_num /= dev .or. is_initial)                                   &
+     &      stop 2
+       end if
+      end do
+      end
diff --git a/libgomp/testsuite/libgomp.fortran/target-is-initial-host.f90 b/libgomp/testsuite/libgomp.fortran/target-is-initial-host.f90
new file mode 100644
index 00000000000..f8a645fc488
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/target-is-initial-host.f90
@@ -0,0 +1,35 @@ 
+! Check whether 'omp_is_initial_device()' is properly compile-time optimized. */
+
+! { dg-additional-options "-fdump-tree-gimple -fdump-tree-optimized" }
+! { dg-additional-options -foffload-options=-fdump-tree-optimized { target { offload_device_nvptx || offload_target_amdgcn } } }
+
+! { dg-final { scan-tree-dump-times "omp_is_initial_device" 1 "gimple" } }
+
+! { dg-final { scan-tree-dump-not "omp_is_initial_device" "optimized" } }
+
+! { dg-final { only_for_offload_target amdgcn-amdhsa scan-offload-tree-dump-not "omp_is_initial_device" "optimized" { target offload_target_amdgcn } } }
+! { dg-final { only_for_offload_target nvptx-none scan-offload-tree-dump-not "omp_is_initial_device" "optimized" { target offload_target_nvptx } } }
+
+
+program main
+  use omp_lib
+  implicit none (type, external)
+  integer :: dev_num, initial, dev
+  logical :: is_initial
+
+  initial = omp_get_initial_device()
+  do dev = omp_initial_device, omp_get_num_devices()
+      dev_num = 99
+      !$omp target map(from: is_initial, dev_num) device(dev)
+        is_initial = omp_is_initial_device ()
+        dev_num = omp_get_device_num ()
+      !$omp end target
+      if (dev == omp_initial_device .or. dev == initial) then
+        if (dev_num /= initial .or. .not. is_initial) &
+          stop 1
+      else
+        if (dev_num /= dev .or. is_initial) &
+          stop 2
+      end if
+  end do
+end