[5/5] OpenMP: Enable 'declare mapper' mappers for 'target update' directives

diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 079d1eaafaa..0998d875e3f 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1271,10 +1271,12 @@  enum c_omp_region_type
   C_ORT_DECLARE_SIMD		= 1 << 2,
   C_ORT_TARGET			= 1 << 3,
   C_ORT_EXIT_DATA		= 1 << 4,
+  C_ORT_UPDATE			= 1 << 5,
   C_ORT_DECLARE_MAPPER		= 1 << 6,
   C_ORT_OMP_DECLARE_SIMD	= C_ORT_OMP | C_ORT_DECLARE_SIMD,
   C_ORT_OMP_TARGET		= C_ORT_OMP | C_ORT_TARGET,
   C_ORT_OMP_EXIT_DATA		= C_ORT_OMP | C_ORT_EXIT_DATA,
+  C_ORT_OMP_UPDATE		= C_ORT_OMP | C_ORT_UPDATE,
   C_ORT_OMP_DECLARE_MAPPER	= C_ORT_OMP | C_ORT_DECLARE_MAPPER,
   C_ORT_ACC_TARGET		= C_ORT_ACC | C_ORT_TARGET
 };
diff --git a/gcc/c-family/c-omp.cc b/gcc/c-family/c-omp.cc
index 2ddb30b54f8..9ff09b59bc6 100644
--- a/gcc/c-family/c-omp.cc
+++ b/gcc/c-family/c-omp.cc
@@ -5176,12 +5176,37 @@  omp_map_decayed_kind (enum gomp_map_kind mapper_kind,
   return omp_join_map_kind (decay_to, force_p, always_p, present_p);
 }
 
+/* Return a name to use for a "basic" map kind, e.g. as output from
+   omp_split_map_kind above.  */
+
+static const char *
+omp_basic_map_kind_name (enum gomp_map_kind kind)
+{
+  switch (kind)
+    {
+    case GOMP_MAP_ALLOC:
+      return "alloc";
+    case GOMP_MAP_TO:
+      return "to";
+    case GOMP_MAP_FROM:
+      return "from";
+    case GOMP_MAP_TOFROM:
+      return "tofrom";
+    case GOMP_MAP_RELEASE:
+      return "release";
+    case GOMP_MAP_DELETE:
+      return "delete";
+    default:
+      gcc_unreachable ();
+    }
+}
+
 /* Instantiate a mapper MAPPER for expression EXPR, adding new clauses to
    OUTLIST.  OUTER_KIND is the mapping kind to use if not already specified in
    the mapper declaration.  */
 
 static tree *
-omp_instantiate_mapper (tree *outlist, tree mapper, tree expr,
+omp_instantiate_mapper (location_t loc, tree *outlist, tree mapper, tree expr,
 			enum gomp_map_kind outer_kind,
 			enum c_omp_region_type ort)
 {
@@ -5214,7 +5239,6 @@  omp_instantiate_mapper (tree *outlist, tree mapper, tree expr,
 
       if (TREE_CODE (t) == OMP_ARRAY_SECTION)
 	{
-	  location_t loc = OMP_CLAUSE_LOCATION (c);
 	  tree t2 = lang_hooks.decls.omp_map_array_section (loc, t);
 
 	  if (t2 == t)
@@ -5240,9 +5264,13 @@  omp_instantiate_mapper (tree *outlist, tree mapper, tree expr,
 
       walk_tree (&unshared, remap_mapper_decl_1, &map_info, NULL);
 
+      OMP_CLAUSE_LOCATION (unshared) = loc;
+
       enum gomp_map_kind decayed_kind
 	= omp_map_decayed_kind (clause_kind, outer_kind,
-				(ort & C_ORT_EXIT_DATA) != 0);
+				(ort & C_ORT_EXIT_DATA) != 0
+				|| (outer_kind == GOMP_MAP_FROM
+				    && (ort & C_ORT_UPDATE) != 0));
       OMP_CLAUSE_SET_MAP_KIND (unshared, decayed_kind);
 
       type = TYPE_MAIN_VARIANT (type);
@@ -5260,7 +5288,7 @@  omp_instantiate_mapper (tree *outlist, tree mapper, tree expr,
 	    = lang_hooks.decls.omp_extract_mapper_directive (mapper_fn);
 	  if (nested_mapper != mapper)
 	    {
-	      outlist = omp_instantiate_mapper (outlist, nested_mapper,
+	      outlist = omp_instantiate_mapper (loc, outlist, nested_mapper,
 						t, outer_kind, ort);
 	      continue;
 	    }
@@ -5271,8 +5299,51 @@  omp_instantiate_mapper (tree *outlist, tree mapper, tree expr,
 	  continue;
 	}
 
-      *outlist = unshared;
-      outlist = &OMP_CLAUSE_CHAIN (unshared);
+      if (ort & C_ORT_UPDATE)
+	{
+	  bool force_p, always_p, present_p;
+	  decayed_kind
+	    = omp_split_map_kind (decayed_kind, &force_p, &always_p,
+				  &present_p);
+	  /* We don't expect to see these flags here.  */
+	  gcc_assert (!force_p && !always_p);
+	  /* For a "target update" operation, we want to turn the map node
+	     expanded from the mapper back into a OMP_CLAUSE_TO or
+	     OMP_CLAUSE_FROM node.  If we can do neither, emit a warning and
+	     drop the clause.  */
+	  switch (decayed_kind)
+	    {
+	    case GOMP_MAP_TO:
+	    case GOMP_MAP_FROM:
+	      {
+		tree xfer
+		  = build_omp_clause (loc, (decayed_kind == GOMP_MAP_TO
+					    ? OMP_CLAUSE_TO : OMP_CLAUSE_FROM));
+		OMP_CLAUSE_DECL (xfer) = OMP_CLAUSE_DECL (unshared);
+		OMP_CLAUSE_SIZE (xfer) = OMP_CLAUSE_SIZE (unshared);
+		/* For FROM/TO clauses, "present" is represented by a flag.
+		   Set it for the expanded clause here.  */
+		if (present_p)
+		  OMP_CLAUSE_MOTION_PRESENT (xfer) = 1;
+		*outlist = xfer;
+		outlist = &OMP_CLAUSE_CHAIN (xfer);
+	      }
+	      break;
+	    default:
+	      clause_kind
+		= omp_split_map_kind (clause_kind, &force_p, &always_p,
+				      &present_p);
+	      warning_at (loc, 0, "dropping %qs clause during mapper expansion "
+			  "in %<#pragma omp target update%>",
+			  omp_basic_map_kind_name (clause_kind));
+	      inform (OMP_CLAUSE_LOCATION (c), "for map clause here");
+	    }
+	}
+      else
+	{
+	  *outlist = unshared;
+	  outlist = &OMP_CLAUSE_CHAIN (unshared);
+	}
     }
 
   return outlist;
@@ -5290,17 +5361,25 @@  c_omp_instantiate_mappers (tree clauses, enum c_omp_region_type ort)
   for (pc = &clauses, c = clauses; c; c = *pc)
     {
       bool using_mapper = false;
+      bool update_p = false, update_present_p = false;
 
       switch (OMP_CLAUSE_CODE (c))
 	{
+	case OMP_CLAUSE_TO:
+	case OMP_CLAUSE_FROM:
+	  update_p = true;
+	  if (OMP_CLAUSE_MOTION_PRESENT (c))
+	    update_present_p = true;
+	  /* Fallthrough.  */
 	case OMP_CLAUSE_MAP:
 	  {
 	    tree t = OMP_CLAUSE_DECL (c);
 	    tree type = NULL_TREE;
 	    bool nonunit_array_with_mapper = false;
 
-	    if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_PUSH_MAPPER_NAME
-		|| OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_POP_MAPPER_NAME)
+	    if (!update_p
+		&& (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_PUSH_MAPPER_NAME
+		    || OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_POP_MAPPER_NAME))
 	      {
 		if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_PUSH_MAPPER_NAME)
 		  mapper_name = OMP_CLAUSE_DECL (c);
@@ -5337,9 +5416,22 @@  c_omp_instantiate_mappers (tree clauses, enum c_omp_region_type ort)
 		continue;
 	      }
 
-	    enum gomp_map_kind kind = OMP_CLAUSE_MAP_KIND (c);
-	    if (kind == GOMP_MAP_UNSET)
-	      kind = GOMP_MAP_TOFROM;
+	    enum gomp_map_kind kind;
+	    if (update_p)
+	      {
+		if (OMP_CLAUSE_CODE (c) == OMP_CLAUSE_TO)
+		  kind = update_present_p ? GOMP_MAP_PRESENT_TO
+					  : GOMP_MAP_TO;
+		else
+		  kind = update_present_p ? GOMP_MAP_PRESENT_FROM
+					  : GOMP_MAP_FROM;
+	      }
+	    else
+	      {
+		kind = OMP_CLAUSE_MAP_KIND (c);
+		if (kind == GOMP_MAP_UNSET)
+		  kind = GOMP_MAP_TOFROM;
+	      }
 
 	    type = TYPE_MAIN_VARIANT (type);
 
@@ -5356,7 +5448,8 @@  c_omp_instantiate_mappers (tree clauses, enum c_omp_region_type ort)
 	      {
 		tree mapper
 		  = lang_hooks.decls.omp_extract_mapper_directive (mapper_fn);
-		pc = omp_instantiate_mapper (pc, mapper, t, kind, ort);
+		pc = omp_instantiate_mapper (OMP_CLAUSE_LOCATION (c),
+					     pc, mapper, t, kind, ort);
 		using_mapper = true;
 	      }
 	    else if (mapper_name)
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index f1348a7e5f3..b37c2d60593 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -14196,7 +14196,9 @@  c_parser_omp_variable_list (c_parser *parser,
 	  bool save_c_omp_array_shaping_op_p = c_omp_array_shaping_op_p;
 	  c_omp_array_section_p = true;
 	  c_omp_array_shaping_op_p
-	    = (kind == OMP_CLAUSE_TO || kind == OMP_CLAUSE_FROM);
+	    = (kind == OMP_CLAUSE_TO
+	       || kind == OMP_CLAUSE_FROM
+	       || ort == C_ORT_OMP_DECLARE_MAPPER);
 	  c_expr expr = c_parser_expr_no_commas (parser, NULL);
 	  if (expr.value != error_mark_node)
 	    mark_exp_read (expr.value);
@@ -18078,7 +18080,9 @@  c_parser_omp_clause_map (c_parser *parser, tree list, enum gomp_map_kind kind)
     }
 
   nl = c_parser_omp_variable_list (parser, clause_loc, OMP_CLAUSE_MAP, list,
-				   C_ORT_OMP, true);
+				   (kind == GOMP_MAP_UNSET
+				    ? C_ORT_OMP_DECLARE_MAPPER
+				    : C_ORT_OMP), true);
 
   tree last_new = NULL_TREE;
 
@@ -18355,26 +18359,148 @@  c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
   if (!parens.require_open (parser))
     return list;
 
-  bool present = false;
-  c_token *token = c_parser_peek_token (parser);
+  int pos = 1, colon_pos = 0;
 
-  if (token->type == CPP_NAME
-      && strcmp (IDENTIFIER_POINTER (token->value), "present") == 0
-      && c_parser_peek_2nd_token (parser)->type == CPP_COLON)
+  while (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_NAME)
     {
-      present = true;
-      c_parser_consume_token (parser);
-      c_parser_consume_token (parser);
+      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type == CPP_COMMA)
+	pos += 2;
+      else if (c_parser_peek_nth_token_raw (parser, pos + 1)->type
+	       == CPP_OPEN_PAREN)
+	{
+	  unsigned int npos = pos + 2;
+	  if (c_parser_check_balanced_raw_token_sequence (parser, &npos)
+	     && (c_parser_peek_nth_token_raw (parser, npos)->type
+		 == CPP_CLOSE_PAREN))
+	    pos = npos + 1;
+	}
+      else
+	pos++;
+      if (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_COLON)
+	{
+	  colon_pos = pos;
+	  break;
+	}
     }
 
+  int present_modifier = false;
+  int mapper_modifier = false;
+  tree mapper_name = NULL_TREE;
+
+  for (int pos = 1; pos < colon_pos; ++pos)
+    {
+      c_token *tok = c_parser_peek_token (parser);
+      if (tok->type == CPP_COMMA)
+	{
+	  c_parser_consume_token (parser);
+	  continue;
+	}
+      const char *p = IDENTIFIER_POINTER (tok->value);
+      if (strcmp ("present", p) == 0)
+	{
+	  if (present_modifier)
+	    {
+	      c_parser_error (parser, "too many %<present%> modifiers");
+	      parens.skip_until_found_close (parser);
+	      return list;
+	    }
+	  present_modifier++;
+	  c_parser_consume_token (parser);
+	}
+      else if (strcmp ("mapper", p) == 0)
+	{
+	  c_parser_consume_token (parser);
+
+	  matching_parens mparens;
+	  if (mparens.require_open (parser))
+	    {
+	      if (mapper_modifier)
+		{
+		  c_parser_error (parser, "too many %<mapper%> modifiers");
+		  /* Assume it's a well-formed mapper modifier, even if it
+		     seems to be in the wrong place.  */
+		  c_parser_consume_token (parser);
+		  mparens.require_close (parser);
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+
+	      tok = c_parser_peek_token (parser);
+
+	      switch (tok->type)
+		{
+		case CPP_NAME:
+		  {
+		    mapper_name = tok->value;
+		    c_parser_consume_token (parser);
+		  }
+		  break;
+
+		case CPP_KEYWORD:
+		  if (tok->keyword == RID_DEFAULT)
+		    {
+		      c_parser_consume_token (parser);
+		      break;
+		    }
+		  /* Fallthrough.  */
+
+		default:
+		  error_at (tok->location,
+			    "expected identifier or %<default%>");
+		  return list;
+		}
+
+	      if (!mparens.require_close (parser))
+		{
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+
+	      mapper_modifier++;
+	      pos += 3;
+	    }
+	}
+      else
+	{
+	  c_parser_error (parser, "%<to%> or %<from%> clause with modifier "
+			  "other than %<present%> or %<mapper%>");
+	  parens.skip_until_found_close (parser);
+	  return list;
+	}
+    }
+
+  if (colon_pos)
+    c_parser_require (parser, CPP_COLON, "expected %<:%>");
+
   tree nl = c_parser_omp_variable_list (parser, loc, kind, list, C_ORT_OMP,
 					true);
   parens.skip_until_found_close (parser);
 
-  if (present)
+  if (present_modifier)
     for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
       OMP_CLAUSE_MOTION_PRESENT (c) = 1;
 
+  if (mapper_name)
+    {
+      tree last_new = NULL_TREE;
+      for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
+	last_new = c;
+
+      tree name = build_omp_clause (input_location, OMP_CLAUSE_MAP);
+      OMP_CLAUSE_SET_MAP_KIND (name, GOMP_MAP_PUSH_MAPPER_NAME);
+      OMP_CLAUSE_DECL (name) = mapper_name;
+      OMP_CLAUSE_CHAIN (name) = nl;
+      nl = name;
+
+      gcc_assert (last_new);
+
+      name = build_omp_clause (input_location, OMP_CLAUSE_MAP);
+      OMP_CLAUSE_SET_MAP_KIND (name, GOMP_MAP_POP_MAPPER_NAME);
+      OMP_CLAUSE_DECL (name) = null_pointer_node;
+      OMP_CLAUSE_CHAIN (name) = OMP_CLAUSE_CHAIN (last_new);
+      OMP_CLAUSE_CHAIN (last_new) = name;
+    }
+
   return nl;
 }
 
@@ -23023,7 +23149,9 @@  c_parser_omp_target_update (location_t loc, c_parser *parser,
 
   tree clauses
     = c_parser_omp_all_clauses (parser, OMP_TARGET_UPDATE_CLAUSE_MASK,
-				"#pragma omp target update");
+				"#pragma omp target update", false);
+  clauses = c_omp_instantiate_mappers (clauses, C_ORT_OMP_UPDATE);
+  clauses = c_finish_omp_clauses (clauses, C_ORT_OMP_UPDATE);
   bool to_clause = false, from_clause = false;
   for (tree c = clauses;
        c && !to_clause && !from_clause;
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 4984accb0bd..f7576c5d137 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -37770,7 +37770,8 @@  cp_parser_omp_var_list_no_open (cp_parser *parser, enum omp_clause_code kind,
 	  auto s = make_temp_override (parser->omp_array_section_p, true);
 	  auto o = make_temp_override (parser->omp_array_shaping_op_p,
 				       (kind == OMP_CLAUSE_TO
-					|| kind == OMP_CLAUSE_FROM));
+					|| kind == OMP_CLAUSE_FROM
+					|| ort == C_ORT_OMP_DECLARE_MAPPER));
 	  tree reshaped_to = NULL_TREE;
 	  token = cp_lexer_peek_token (parser->lexer);
 	  location_t loc = token->location;
@@ -41308,24 +41309,153 @@  cp_parser_omp_clause_from_to (cp_parser *parser, enum omp_clause_code kind,
   if (!cp_parser_require (parser, CPP_OPEN_PAREN, RT_OPEN_PAREN))
     return list;
 
-  bool present = false;
-  cp_token *token = cp_lexer_peek_token (parser->lexer);
+  int pos = 1;
+  int colon_pos = 0;
 
-  if (token->type == CPP_NAME
-      && strcmp (IDENTIFIER_POINTER (token->u.value), "present") == 0
-      && cp_lexer_nth_token_is (parser->lexer, 2, CPP_COLON))
+  while (cp_lexer_peek_nth_token (parser->lexer, pos)->type == CPP_NAME)
     {
-      present = true;
-      cp_lexer_consume_token (parser->lexer);
-      cp_lexer_consume_token (parser->lexer);
+      if (cp_lexer_peek_nth_token (parser->lexer, pos + 1)->type == CPP_COMMA)
+	pos += 2;
+      else if (cp_lexer_peek_nth_token (parser->lexer, pos + 1)->type
+	       == CPP_OPEN_PAREN)
+	pos = cp_parser_skip_balanced_tokens (parser, pos + 1);
+      else
+	pos++;
+      if (cp_lexer_peek_nth_token (parser->lexer, pos)->type == CPP_COLON)
+	{
+	  colon_pos = pos;
+	  break;
+	}
     }
 
+  bool present_modifier = false;
+  bool mapper_modifier = false;
+  tree mapper_name = NULL_TREE;
+
+  for (int pos = 1; pos < colon_pos; ++pos)
+    {
+      cp_token *tok = cp_lexer_peek_token (parser->lexer);
+      if (tok->type == CPP_COMMA)
+	{
+	  cp_lexer_consume_token (parser->lexer);
+	  continue;
+	}
+      const char *p = IDENTIFIER_POINTER (tok->u.value);
+      if (strcmp ("present", p) == 0)
+	{
+	  if (present_modifier)
+	    {
+	      cp_parser_error (parser, "too many %<present%> modifiers");
+	      cp_parser_skip_to_closing_parenthesis (parser,
+						     /*recovering=*/true,
+						     /*or_comma=*/false,
+						     /*consume_paren=*/true);
+	      return list;
+	    }
+	  present_modifier = true;
+	  cp_lexer_consume_token (parser->lexer);
+	}
+      else if (strcmp ("mapper", p) == 0)
+	{
+	  cp_lexer_consume_token (parser->lexer);
+	  matching_parens parens;
+	  if (parens.require_open (parser))
+	    {
+	      if (mapper_modifier)
+		{
+		  cp_parser_error (parser, "too many %<mapper%> modifiers");
+		  /* Assume it's a well-formed mapper modifier, even if it
+		     seems to be in the wrong place.  */
+		  cp_lexer_consume_token (parser->lexer);
+		  parens.require_close (parser);
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/
+							 true);
+		  return list;
+		}
+	      tok = cp_lexer_peek_token (parser->lexer);
+	      switch (tok->type)
+		{
+		case CPP_NAME:
+		  {
+		    cp_expr e = cp_parser_identifier (parser);
+		    if (e != error_mark_node)
+		      mapper_name = e;
+		    else
+		      goto err;
+		  }
+		  break;
+		case CPP_KEYWORD:
+		  if (tok->keyword == RID_DEFAULT)
+		    {
+		      cp_lexer_consume_token (parser->lexer);
+		      break;
+		    }
+		  /* Fallthrough.  */
+		default:
+		err:
+		  cp_parser_error (parser,
+				   "expected identifier or %<default%>");
+		  return list;
+		}
+
+	      if (!parens.require_close (parser))
+		{
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/
+							 true);
+		  return list;
+		}
+	      mapper_modifier = true;
+	      pos += 3;
+	    }
+	  else
+	    {
+	      cp_parser_error (parser, "%<to%> or %<from%> clause with "
+			       "modifier other than %<present%> or %<mapper%>");
+	      cp_parser_skip_to_closing_parenthesis (parser,
+						     /*recovering=*/true,
+						     /*or_comma=*/false,
+						     /*consume_paren=*/true);
+	      return list;
+	    }
+	}
+    }
+
+  if (colon_pos)
+    cp_parser_require (parser, CPP_COLON, RT_COLON);
+
   tree nl = cp_parser_omp_var_list_no_open (parser, kind, list, NULL, C_ORT_OMP,
 					    true);
-  if (present)
+  if (present_modifier)
     for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
       OMP_CLAUSE_MOTION_PRESENT (c) = 1;
 
+  if (mapper_name)
+    {
+      tree last_new = NULL_TREE;
+      for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
+	last_new = c;
+
+      tree name = build_omp_clause (input_location, OMP_CLAUSE_MAP);
+      OMP_CLAUSE_SET_MAP_KIND (name, GOMP_MAP_PUSH_MAPPER_NAME);
+      OMP_CLAUSE_DECL (name) = mapper_name;
+      OMP_CLAUSE_CHAIN (name) = nl;
+      nl = name;
+
+      gcc_assert (last_new);
+
+      name = build_omp_clause (input_location, OMP_CLAUSE_MAP);
+      OMP_CLAUSE_SET_MAP_KIND (name, GOMP_MAP_POP_MAPPER_NAME);
+      OMP_CLAUSE_DECL (name) = null_pointer_node;
+      OMP_CLAUSE_CHAIN (name) = OMP_CLAUSE_CHAIN (last_new);
+      OMP_CLAUSE_CHAIN (last_new) = name;
+    }
+
   return nl;
 }
 
@@ -41559,7 +41689,9 @@  cp_parser_omp_clause_map (cp_parser *parser, tree list, enum gomp_map_kind kind)
      legally.  */
   begin_scope (sk_omp, NULL);
   nlist = cp_parser_omp_var_list_no_open (parser, OMP_CLAUSE_MAP, list,
-					  NULL, C_ORT_OMP, true);
+					  NULL, (kind == GOMP_MAP_UNSET
+						 ? C_ORT_OMP_DECLARE_MAPPER
+						 : C_ORT_OMP), true);
   finish_scope ();
 
   tree last_new = NULL_TREE;
@@ -46931,7 +47063,11 @@  cp_parser_omp_target_update (cp_parser *parser, cp_token *pragma_tok,
 
   tree clauses
     = cp_parser_omp_all_clauses (parser, OMP_TARGET_UPDATE_CLAUSE_MASK,
-				 "#pragma omp target update", pragma_tok);
+				 "#pragma omp target update", pragma_tok,
+				 false);
+  if (!processing_template_decl)
+    clauses = c_omp_instantiate_mappers (clauses, C_ORT_OMP_UPDATE);
+  clauses = finish_omp_clauses (clauses, C_ORT_OMP_UPDATE);
   bool to_clause = false, from_clause = false;
   for (tree c = clauses;
        c && !to_clause && !from_clause;
diff --git a/gcc/fortran/openmp.cc b/gcc/fortran/openmp.cc
index ba2a8221b96..96e764b90a6 100644
--- a/gcc/fortran/openmp.cc
+++ b/gcc/fortran/openmp.cc
@@ -1448,16 +1448,68 @@  gfc_match_motion_var_list (const char *str, gfc_omp_namelist **list,
   if (m != MATCH_YES)
     return m;
 
-  match m_present = gfc_match (" present : ");
+  locus old_loc = gfc_current_locus;
+  int present_modifier = 0;
+  int mapper_modifier = 0;
+  locus second_mapper_locus = old_loc;
+  locus second_present_locus = old_loc;
+  char mapper_id[GFC_MAX_SYMBOL_LEN + 1] = { '\0' };
+
+  for (;;)
+    {
+      locus current_locus = gfc_current_locus;
+      if (gfc_match ("present ") == MATCH_YES)
+	{
+	  if (present_modifier++ == 1)
+	    second_present_locus = current_locus;
+	}
+      else if (gfc_match ("mapper ( ") == MATCH_YES)
+	{
+	  if (mapper_modifier++ == 1)
+	    second_mapper_locus = current_locus;
+	  m = gfc_match (" %n ) ", mapper_id);
+	  if (m != MATCH_YES)
+	    return m;
+	  if (strcmp (mapper_id, "default") == 0)
+	    mapper_id[0] = '\0';
+	}
+      else
+	break;
+      gfc_match (", ");
+    }
+
+  if (gfc_match (" : ") != MATCH_YES)
+    {
+      gfc_current_locus = old_loc;
+      present_modifier = 0;
+      mapper_modifier = 0;
+    }
+
+  if (present_modifier > 1)
+    {
+      gfc_error ("too many %<present%> modifiers at %L", &second_present_locus);
+      return MATCH_ERROR;
+    }
+  if (mapper_modifier > 1)
+    {
+      gfc_error ("too many %<mapper%> modifiers at %L", &second_mapper_locus);
+      return MATCH_ERROR;
+    }
 
   m = gfc_match_omp_variable_list ("", list, false, NULL, headp, true, true);
   if (m != MATCH_YES)
     return m;
-  if (m_present == MATCH_YES)
+  gfc_omp_namelist *n;
+  for (n = **headp; n; n = n->next)
     {
-      gfc_omp_namelist *n;
-      for (n = **headp; n; n = n->next)
+      if (present_modifier)
 	n->u.present_modifier = true;
+
+      if (mapper_id[0] != '\0')
+	{
+	  n->u2.udm = gfc_get_omp_namelist_udm ();
+	  n->u2.udm->mapper_id = gfc_get_string ("%s", mapper_id);
+	}
     }
   return MATCH_YES;
 }
@@ -3215,10 +3267,15 @@  gfc_match_omp_clauses (gfc_omp_clauses **cp, const omp_mask mask,
 					      &c->lists[OMP_LIST_FIRSTPRIVATE],
 					      true) == MATCH_YES)
 	    continue;
-	  if ((mask & OMP_CLAUSE_FROM)
-	      && gfc_match_motion_var_list ("from (", &c->lists[OMP_LIST_FROM],
-					     &head) == MATCH_YES)
-	    continue;
+	  if (mask & OMP_CLAUSE_FROM)
+	    {
+	      m = gfc_match_motion_var_list ("from (", &c->lists[OMP_LIST_FROM],
+					     &head);
+	      if (m == MATCH_YES)
+		continue;
+	      else if (m == MATCH_ERROR)
+		goto error;
+	    }
 	  if ((mask & OMP_CLAUSE_UNROLL_FULL)
 	      && (m = gfc_match_dupl_check (!c->unroll_full, "full"))
 		     != MATCH_NO)
@@ -4240,10 +4297,15 @@  gfc_match_omp_clauses (gfc_omp_clauses **cp, const omp_mask mask,
 	      if (m == MATCH_YES)
 		continue;
 	    }
-	  else if ((mask & OMP_CLAUSE_TO)
-		   && gfc_match_motion_var_list ("to (", &c->lists[OMP_LIST_TO],
-						 &head) == MATCH_YES)
-	    continue;
+	  else if (mask & OMP_CLAUSE_TO)
+	    {
+	      m = gfc_match_motion_var_list ("to (", &c->lists[OMP_LIST_TO],
+						 &head);
+	      if (m == MATCH_YES)
+		continue;
+	      else if (m == MATCH_ERROR)
+		goto error;
+	    }
 	  break;
 	case 'u':
 	  if ((mask & OMP_CLAUSE_UNIFORM)
diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc
index 170615974b3..746efb75369 100644
--- a/gcc/fortran/trans-openmp.cc
+++ b/gcc/fortran/trans-openmp.cc
@@ -6171,11 +6171,14 @@  gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,
 		  gcc_unreachable ();
 		}
 
+	      gfc_ref *lastref = NULL;
+	      if (n->expr)
+		for (gfc_ref *ref = n->expr->ref; ref; ref = ref->next)
+		  if (ref->type == REF_COMPONENT || ref->type == REF_ARRAY)
+		    lastref = ref;
+
 	      if ((list == OMP_LIST_TO || list == OMP_LIST_FROM)
-		  && (!n->expr
-		       || (n->expr
-			   && n->expr->ref
-			   && n->expr->ref->type == REF_ARRAY))
+		  && (!n->expr || (lastref && lastref->type == REF_ARRAY))
 		  && !gfc_omp_contiguous_update_p (n))
 		{
 		  int ndims;
@@ -6197,7 +6200,7 @@  gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,
 			 or other data between elements, e.g. of a derived-type
 			 array).  */
 		      span = gfc_get_array_span (desc, n->expr);
-		      ndims = n->expr->ref->u.ar.dimen;
+		      ndims = lastref->u.ar.dimen;
 		    }
 		  else
 		    {
@@ -10568,7 +10571,12 @@  gfc_trans_omp_target_update (gfc_code *code)
   tree stmt, omp_clauses;
 
   gfc_start_block (&block);
-  omp_clauses = gfc_trans_omp_clauses (&block, code->ext.omp_clauses,
+  gfc_omp_clauses *target_update_clauses = code->ext.omp_clauses;
+  gfc_omp_instantiate_mappers (code, target_update_clauses, TOC_OPENMP,
+			       OMP_LIST_TO);
+  gfc_omp_instantiate_mappers (code, target_update_clauses, TOC_OPENMP,
+			       OMP_LIST_FROM);
+  omp_clauses = gfc_trans_omp_clauses (&block, target_update_clauses,
 				       code->loc);
   stmt = build1_loc (input_location, OMP_TARGET_UPDATE, void_type_node,
 		     omp_clauses);
diff --git a/gcc/testsuite/c-c++-common/gomp/declare-mapper-17.c b/gcc/testsuite/c-c++-common/gomp/declare-mapper-17.c
new file mode 100644
index 00000000000..ddbb59e4f7f
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/declare-mapper-17.c
@@ -0,0 +1,38 @@ 
+/* { dg-do compile } */
+/* { dg-additional-options "-fdump-tree-original" } */
+
+typedef struct {
+  int a, b, c, d;
+} S;
+
+#pragma omp declare mapper (S s) map(alloc: s.a) map(to: s.b) map(from: s.c) \
+				 map(tofrom: s.d)
+#pragma omp declare mapper (update: S s) map(s.a, s.b, s.c, s.d)
+
+int main()
+{
+  S v;
+#pragma omp target update to(v)
+/* { dg-warning {dropping .from. clause during mapper expansion in .#pragma omp target update.} "" { target *-*-* } .-1 } */
+/* { dg-warning {dropping .alloc. clause during mapper expansion in .#pragma omp target update.} "" { target *-*-* } .-2 } */
+/* { dg-final { scan-tree-dump-times {(?n)update to\(v\.d\) to\(v\.b\)$} 1 "original" } } */
+#pragma omp target update from(v)
+/* { dg-warning {dropping .to. clause during mapper expansion in .#pragma omp target update.} "" { target *-*-* } .-1 } */
+/* { dg-warning {dropping .alloc. clause during mapper expansion in .#pragma omp target update.} "" { target *-*-* } .-2 } */
+/* { dg-final { scan-tree-dump-times {(?n)update from\(v\.d\) from\(v\.c\)$} 1 "original" } } */
+
+#pragma omp target update to(mapper(update): v)
+/* { dg-final { scan-tree-dump-times {(?n)update to\(v\.d\) to\(v\.c\) to\(v\.b\) to\(v\.a\)$} 1 "original" } } */
+#pragma omp target update from(mapper(update): v)
+/* { dg-final { scan-tree-dump-times {(?n)update from\(v\.d\) from\(v\.c\) from\(v\.b\) from\(v\.a\)$} 1 "original" } } */
+
+#pragma omp target update to(present, mapper(update): v)
+/* { dg-final { scan-tree-dump-times {(?n)update to\(present:v\.d\) to\(present:v\.c\) to\(present:v\.b\) to\(present:v\.a\)$} 2 "original" } } */
+#pragma omp target update from(present, mapper(update): v)
+/* { dg-final { scan-tree-dump-times {(?n)update from\(present:v\.d\) from\(present:v\.c\) from\(present:v\.b\) from\(present:v\.a\)$} 2 "original" } } */
+
+#pragma omp target update to(present: v.a, v.b, v.c, v.d)
+#pragma omp target update from(present: v.a, v.b, v.c, v.d)
+
+  return 0;
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/declare-mapper-19.c b/gcc/testsuite/c-c++-common/gomp/declare-mapper-19.c
new file mode 100644
index 00000000000..fd40c6a25e8
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/declare-mapper-19.c
@@ -0,0 +1,40 @@ 
+/* { dg-do compile } */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+
+typedef struct {
+  int *ptr;
+} S;
+
+int main(void)
+{
+#pragma omp declare mapper(grid: S x) map(([9][11]) x.ptr[3:3:2][1:4:3])
+  S q;
+  q.ptr = (int *) calloc (9 * 11, sizeof (int));
+
+  /* The 'grid' mapper specifies a noncontiguous region, so it can't be used
+     for 'map' like this.  */
+#pragma omp target enter data map(mapper(grid), to: q)
+/* { dg-error {array section is not contiguous in .map. clause} "" { target *-*-* } .-1 } */
+/* { dg-error {.#pragma omp target enter data. must contain at least one .map. clause} "" { target *-*-* } .-2 } */
+
+#pragma omp target
+  for (int i = 0; i < 9*11; i++)
+    q.ptr[i] = i;
+
+  /* It's OK on a 'target update' directive though.  */
+#pragma omp target update from(mapper(grid): q)
+
+  for (int j = 0; j < 9; j++)
+    for (int i = 0; i < 11; i++)
+      if (j >= 3 && j <= 7 && ((j - 3) % 2) == 0
+	  && i >= 1 && i <= 10 && ((i - 1) % 3) == 0)
+	assert (q.ptr[j * 11 + i] == j * 11 + i);
+
+#pragma omp target exit data map(mapper(grid), release: q)
+/* { dg-error {array section is not contiguous in .map. clause} "" { target *-*-* } .-1 } */
+/* { dg-error {.#pragma omp target exit data. must contain at least one .map. clause} "" { target *-*-* } .-2 } */
+  return 0;
+}
diff --git a/gcc/testsuite/gfortran.dg/gomp/declare-mapper-24.f90 b/gcc/testsuite/gfortran.dg/gomp/declare-mapper-24.f90
new file mode 100644
index 00000000000..9555a94bada
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/declare-mapper-24.f90
@@ -0,0 +1,43 @@ 
+! { dg-do compile }
+! { dg-additional-options "-fdump-tree-original" }
+
+type t
+integer :: a, b, c, d
+end type t
+
+type(t) :: tvar
+
+!$omp declare mapper (T :: t) map(alloc: t%a) map(to: t%b) map(from: t%c) &
+!$omp & map(tofrom: t%d)
+
+!$omp declare mapper (updatey: T :: t) map(t%a) map(t%b) map(t%c) map(t%d)
+
+!$omp target update to(tvar)
+! { dg-warning "Dropping incompatible .ALLOC. mapper clause" "" { target *-*-* } .-1 }
+! { dg-warning "Dropping incompatible .FROM. mapper clause" "" { target *-*-* } .-2 }
+! { dg-final { scan-tree-dump-times {(?n)update to\(tvar\.b \[len: [0-9]+\]\) to\(tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+!$omp target update from(tvar)
+! { dg-warning "Dropping incompatible .ALLOC. mapper clause" "" { target *-*-* } .-1 }
+! { dg-warning "Dropping incompatible .TO. mapper clause" "" { target *-*-* } .-2 }
+! { dg-final { scan-tree-dump-times {(?n)update from\(tvar\.c \[len: [0-9]+\]\) from\(tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+
+!$omp target update to(present: tvar)
+! { dg-warning "Dropping incompatible .ALLOC. mapper clause" "" { target *-*-* } .-1 }
+! { dg-warning "Dropping incompatible .FROM. mapper clause" "" { target *-*-* } .-2 }
+! { dg-final { scan-tree-dump-times {(?n)update to\(present:tvar\.b \[len: [0-9]+\]\) to\(present:tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+!$omp target update from(present: tvar)
+! { dg-warning "Dropping incompatible .ALLOC. mapper clause" "" { target *-*-* } .-1 }
+! { dg-warning "Dropping incompatible .TO. mapper clause" "" { target *-*-* } .-2 }
+! { dg-final { scan-tree-dump-times {(?n)update from\(present:tvar\.c \[len: [0-9]+\]\) from\(present:tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+
+!$omp target update to(mapper(updatey): tvar)
+! { dg-final { scan-tree-dump-times {(?n)update to\(tvar\.a \[len: [0-9]+\]\) to\(tvar\.b \[len: [0-9]+\]\) to\(tvar\.c \[len: [0-9]+\]\) to\(tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+!$omp target update from(mapper(updatey): tvar)
+! { dg-final { scan-tree-dump-times {(?n)update from\(tvar\.a \[len: [0-9]+\]\) from\(tvar\.b \[len: [0-9]+\]\) from\(tvar\.c \[len: [0-9]+\]\) from\(tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+
+!$omp target update to(present, mapper(updatey): tvar)
+! { dg-final { scan-tree-dump-times {(?n)update to\(present:tvar\.a \[len: [0-9]+\]\) to\(present:tvar\.b \[len: [0-9]+\]\) to\(present:tvar\.c \[len: [0-9]+\]\) to\(present:tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+!$omp target update from(present, mapper(updatey): tvar)
+! { dg-final { scan-tree-dump-times {(?n)update from\(present:tvar\.a \[len: [0-9]+\]\) from\(present:tvar\.b \[len: [0-9]+\]\) from\(present:tvar\.c \[len: [0-9]+\]\) from\(present:tvar\.d \[len: [0-9]+\]\)$} 1 "original" } }
+
+end
diff --git a/gcc/testsuite/gfortran.dg/gomp/declare-mapper-26.f90 b/gcc/testsuite/gfortran.dg/gomp/declare-mapper-26.f90
index c408b37f5a9..16afb51f48a 100644
--- a/gcc/testsuite/gfortran.dg/gomp/declare-mapper-26.f90
+++ b/gcc/testsuite/gfortran.dg/gomp/declare-mapper-26.f90
@@ -18,8 +18,8 @@  var%arr = 0
 
 var%arr = 1
 
-! But this is fine.  (Re-enabled by later patch.)
-!!$omp target update to(mapper(even): var)
+! But this is fine.
+!$omp target update to(mapper(even): var)
 
 ! As 'enter data'.
 !$omp target exit data map(mapper(even), delete: var)
diff --git a/gcc/testsuite/gfortran.dg/gomp/declare-mapper-27.f90 b/gcc/testsuite/gfortran.dg/gomp/declare-mapper-27.f90
new file mode 100644
index 00000000000..6b3a181acaa
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/declare-mapper-27.f90
@@ -0,0 +1,25 @@ 
+! { dg-do compile }
+
+type t
+integer :: x
+end type t
+
+type(t) :: var
+
+! Error on attempt to use missing named mapper.
+!$omp target update to(mapper(boo): var)
+! { dg-error {User-defined mapper .boo. not found} "" { target *-*-* } .-1 }
+
+var%x = 0
+
+!$omp target map(mapper(boo), tofrom: var)
+! { dg-error {User-defined mapper .boo. not found} "" { target *-*-* } .-1 }
+var%x = 5
+!$omp end target
+
+! These should be fine though...
+!$omp target enter data map(mapper(default), to: var)
+
+!$omp target exit data map(from: var)
+
+end
diff --git a/libgomp/testsuite/libgomp.c-c++-common/declare-mapper-18.c b/libgomp/testsuite/libgomp.c-c++-common/declare-mapper-18.c
new file mode 100644
index 00000000000..50f37cba89d
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/declare-mapper-18.c
@@ -0,0 +1,33 @@ 
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+
+typedef struct {
+  int *ptr;
+} S;
+
+int main(void)
+{
+#pragma omp declare mapper(grid: S x) map(([9][11]) x.ptr[3:3:2][1:4:3])
+  S q;
+  q.ptr = (int *) calloc (9 * 11, sizeof (int));
+
+#pragma omp target enter data map(to: q.ptr, q.ptr[0:9*11])
+
+#pragma omp target
+  for (int i = 0; i < 9*11; i++)
+    q.ptr[i] = i;
+
+#pragma omp target update from(mapper(grid): q)
+
+  for (int j = 0; j < 9; j++)
+    for (int i = 0; i < 11; i++)
+      if (j >= 3 && j <= 7 && ((j - 3) % 2) == 0
+	  && i >= 1 && i <= 10 && ((i - 1) % 3) == 0)
+	assert (q.ptr[j * 11 + i] == j * 11 + i);
+      else
+	assert (q.ptr[j * 11 + i] == 0);
+
+#pragma omp target exit data map(release: q.ptr, q.ptr[0:9*11])
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.fortran/declare-mapper-25.f90 b/libgomp/testsuite/libgomp.fortran/declare-mapper-25.f90
new file mode 100644
index 00000000000..dc1f5272a26
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/declare-mapper-25.f90
@@ -0,0 +1,44 @@ 
+! { dg-do run }
+! { dg-require-effective-target offload_device_nonshared_as }
+
+type t
+integer, allocatable :: arr(:)
+end type t
+
+!$omp declare mapper(odd: T :: tv) map(tv%arr(1::2))
+!$omp declare mapper(even: T :: tv) map(tv%arr(2::2))
+
+type(t) :: var
+integer :: i
+
+allocate(var%arr(100))
+
+var%arr = 0
+
+!$omp target enter data map(to: var)
+
+var%arr = 1
+
+!$omp target update to(mapper(odd): var)
+
+!$omp target
+do i=1,100
+  if (mod(i,2).eq.0.and.var%arr(i).ne.0) stop 1
+  if (mod(i,2).eq.1.and.var%arr(i).ne.1) stop 2
+end do
+!$omp end target
+
+var%arr = 2
+
+!$omp target update to(mapper(even): var)
+
+!$omp target
+do i=1,100
+  if (mod(i,2).eq.0.and.var%arr(i).ne.2) stop 3
+  if (mod(i,2).eq.1.and.var%arr(i).ne.1) stop 4
+end do
+!$omp end target
+
+!$omp target exit data map(delete: var)
+
+end
diff --git a/libgomp/testsuite/libgomp.fortran/declare-mapper-28.f90 b/libgomp/testsuite/libgomp.fortran/declare-mapper-28.f90
new file mode 100644
index 00000000000..6561decc49a
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/declare-mapper-28.f90
@@ -0,0 +1,38 @@ 
+! { dg-do run }
+
+program p
+
+type t
+integer :: x, y
+end type t
+
+type(t) :: var
+
+var%x = 0
+var%y = 0
+
+var = sub(7)
+
+contains
+
+type(t) function sub(arg)
+integer :: arg
+
+!$omp declare mapper (t :: tvar) map(tvar%x, tvar%y)
+
+!$omp target enter data map(alloc: sub)
+
+sub%x = 5
+sub%y = arg
+
+!$omp target update to(sub)
+
+!$omp target
+if (sub%x.ne.5) stop 1
+if (sub%y.ne.7) stop 2
+!$omp end target
+
+!$omp target exit data map(release: sub)
+
+end function sub
+end program p