[v4,3/5] openmp: Add support for iterators in 'target update' clauses (C/C++)

Message ID 46d688e5-347d-4892-a6df-42e9c963adc2@baylibre.com
State New
Headers
Series openmp: Add support for iterators in OpenMP mapping clauses |

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Commit Message

Kwok Cheung Yeung Nov. 28, 2024, 11:36 p.m. UTC
  The target update clause decls and sizes are now Gimplified in 
gimplify_scan_omp_clauses. The rest of the patch is mostly unchanged.
From 79159cbf815d458114e7c6da8dbb138ce24b7df1 Mon Sep 17 00:00:00 2001
From: Kwok Cheung Yeung <kcyeung@baylibre.com>
Date: Wed, 27 Nov 2024 21:51:34 +0000
Subject: [PATCH 3/5] openmp: Add support for iterators in 'target update'
 clauses (C/C++)

This adds support for iterators in 'to' and 'from' clauses in the
'target update' OpenMP directive.

2024-11-27  Kwok Cheung Yeung  <kcyeung@baylibre.com>

	gcc/c/
	* c-parser.cc (c_parser_omp_clause_from_to): Parse 'iterator' modifier.
	* c-typeck.cc (c_finish_omp_clauses): Finish iterators for to/from
	clauses.

	gcc/cp/
	* parser.cc (cp_parser_omp_clause_from_to): Parse 'iterator' modifier.
	* semantics.cc (finish_omp_clauses): Finish iterators for to/from
	clauses.

	gcc/
	* gimplify.cc (gimplify_scan_omp_clauses): Add argument for iterator
	loop sequence.   Gimplify the clause decl and size into the iterator
	loop if iterators are used.
	(gimplify_omp_workshare): Add argument for iterator loops sequence
	in call to gimplify_scan_omp_clauses.
	(gimplify_omp_target_update): Call remove_unused_omp_iterator_vars and
	build_omp_iterators_loops.  Add loop sequence as argument when calling
	gimplify_scan_omp_clauses, gimplify_adjust_omp_clauses and building
	the Gimple statement.
	* tree-pretty-print.cc (dump_omp_clause): Call dump_omp_iterators
	for to/from clauses with iterators.
	* tree.cc (omp_clause_num_ops): Add extra operand for OMP_CLAUSE_FROM
	and OMP_CLAUSE_TO.
	* tree.h (OMP_CLAUSE_HAS_ITERATORS): Add check for OMP_CLAUSE_TO and
	OMP_CLAUSE_FROM.
	(OMP_CLAUSE_ITERATORS): Likewise.

	gcc/testsuite/
	* c-c++-common/gomp/target-update-iterators-1.c: New.
	* c-c++-common/gomp/target-update-iterators-2.c: New.
	* c-c++-common/gomp/target-update-iterators-3.c: New.

	libgomp/
	* target.c (gomp_update): Call gomp_merge_iterator_maps.  Free
	allocated variables.
	* testsuite/libgomp.c-c++-common/target-update-iterators-1.c: New.
	* testsuite/libgomp.c-c++-common/target-update-iterators-2.c: New.
	* testsuite/libgomp.c-c++-common/target-update-iterators-3.c: New.
---
 gcc/c/c-parser.cc                             | 105 +++++++++++++++--
 gcc/c/c-typeck.cc                             |   5 +-
 gcc/cp/parser.cc                              | 111 ++++++++++++++++--
 gcc/cp/semantics.cc                           |   5 +-
 gcc/gimplify.cc                               |  37 +++---
 .../gomp/target-update-iterators-1.c          |  20 ++++
 .../gomp/target-update-iterators-2.c          |  23 ++++
 .../gomp/target-update-iterators-3.c          |  17 +++
 gcc/tree-pretty-print.cc                      |  10 ++
 gcc/tree.cc                                   |   4 +-
 gcc/tree.h                                    |   6 +-
 libgomp/target.c                              |  14 +++
 .../target-update-iterators-1.c               |  65 ++++++++++
 .../target-update-iterators-2.c               |  58 +++++++++
 .../target-update-iterators-3.c               |  67 +++++++++++
 15 files changed, 509 insertions(+), 38 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/gomp/target-update-iterators-1.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/target-update-iterators-2.c
 create mode 100644 gcc/testsuite/c-c++-common/gomp/target-update-iterators-3.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-1.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-2.c
 create mode 100644 libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-3.c
  

Patch

diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index c3e57341850..5d1b17e5b25 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -20037,8 +20037,11 @@  c_parser_omp_clause_device_type (c_parser *parser, tree list)
    to ( variable-list )
 
    OpenMP 5.1:
-   from ( [present :] variable-list )
-   to ( [present :] variable-list ) */
+   from ( [motion-modifier[,] [motion-modifier[,]...]:] variable-list )
+   to ( [motion-modifier[,] [motion-modifier[,]...]:] variable-list )
+
+   motion-modifier:
+     present | iterator (iterators-definition)  */
 
 static tree
 c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
@@ -20049,15 +20052,88 @@  c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
   if (!parens.require_open (parser))
     return list;
 
+  int pos = 1, colon_pos = 0;
+  int iterator_length = 0;
+  while (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_NAME)
+    {
+      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type
+	  == CPP_OPEN_PAREN)
+	{
+	  unsigned int n = pos + 2;
+	  if (c_parser_check_balanced_raw_token_sequence (parser, &n)
+	     && (c_parser_peek_nth_token_raw (parser, n)->type
+		 == CPP_CLOSE_PAREN))
+	    {
+	      iterator_length = n - pos + 1;
+	      pos = n;
+	    }
+	}
+      if (c_parser_peek_nth_token_raw (parser, pos + 1)->type == CPP_COMMA)
+	pos += 2;
+      else
+	pos++;
+      if (c_parser_peek_nth_token_raw (parser, pos)->type == CPP_COLON)
+	{
+	  colon_pos = pos;
+	  break;
+	}
+    }
+
   bool present = false;
-  c_token *token = c_parser_peek_token (parser);
+  tree iterators = NULL_TREE;
 
-  if (token->type == CPP_NAME
-      && strcmp (IDENTIFIER_POINTER (token->value), "present") == 0
-      && c_parser_peek_2nd_token (parser)->type == CPP_COLON)
+  for (pos = 1; pos < colon_pos; pos++)
     {
-      present = true;
-      c_parser_consume_token (parser);
+      c_token *token = c_parser_peek_token (parser);
+
+      if (token->type == CPP_COMMA)
+	{
+	  c_parser_consume_token (parser);
+	  continue;
+	}
+      if (token->type == CPP_NAME)
+	{
+	  const char *name = IDENTIFIER_POINTER (token->value);
+	  if (strcmp (name, "present") == 0)
+	    {
+	      if (present)
+		{
+		  c_parser_error (parser, "too many %<present%> modifiers");
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+	      present = true;
+	      c_parser_consume_token (parser);
+	    }
+	  else if (strcmp (name, "iterator") == 0)
+	    {
+	      if (iterators)
+		{
+		  c_parser_error (parser, "too many %<iterator%> modifiers");
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+	      iterators = c_parser_omp_iterators (parser);
+	      pos += iterator_length - 1;
+	    }
+	  else
+	    {
+	      if (kind == OMP_CLAUSE_TO)
+		c_parser_error (parser, "%<to%> clause with motion modifier "
+				"other than %<iterator%> or %<present%>");
+	      else
+		c_parser_error (parser, "%<from%> clause with motion modifier "
+				"other than %<iterator%> or %<present%>");
+	      parens.skip_until_found_close (parser);
+	      return list;
+	    }
+	}
+    }
+
+  if (colon_pos)
+    {
+      gcc_assert (pos == colon_pos);
+      gcc_assert (c_parser_next_token_is (parser, CPP_COLON));
       c_parser_consume_token (parser);
     }
 
@@ -20068,6 +20144,19 @@  c_parser_omp_clause_from_to (c_parser *parser, enum omp_clause_code kind,
     for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
       OMP_CLAUSE_MOTION_PRESENT (c) = 1;
 
+  if (iterators)
+    {
+      tree block = pop_scope ();
+      if (iterators == error_mark_node)
+	iterators = NULL_TREE;
+      else
+	TREE_VEC_ELT (iterators, 5) = block;
+    }
+
+  if (iterators)
+    for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
+      OMP_CLAUSE_ITERATORS (c) = iterators;
+
   return nl;
 }
 
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 09898828df3..e41489a7498 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -16465,6 +16465,9 @@  c_finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	case OMP_CLAUSE_MAP:
 	  if (OMP_CLAUSE_MAP_IMPLICIT (c) && !implicit_moved)
 	    goto move_implicit;
+	  /* FALLTHRU */
+	case OMP_CLAUSE_TO:
+	case OMP_CLAUSE_FROM:
 	  if (OMP_CLAUSE_ITERATORS (c)
 	      && c_omp_finish_iterators (OMP_CLAUSE_ITERATORS (c)))
 	    {
@@ -16472,8 +16475,6 @@  c_finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	      break;
 	    }
 	  /* FALLTHRU */
-	case OMP_CLAUSE_TO:
-	case OMP_CLAUSE_FROM:
 	case OMP_CLAUSE__CACHE_:
 	  {
 	    using namespace omp_addr_tokenizer;
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 12a3eb7905d..3b852a14dca 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -41851,8 +41851,11 @@  cp_parser_omp_clause_doacross (cp_parser *parser, tree list, location_t loc)
    to ( variable-list )
 
    OpenMP 5.1:
-   from ( [present :] variable-list )
-   to ( [present :] variable-list ) */
+   from ( [motion-modifier[,] [motion-modifier[,]...]:] variable-list )
+   to ( [motion-modifier[,] [motion-modifier[,]...]:] variable-list )
+
+   motion-modifier:
+     present | iterator (iterators-definition)  */
 
 static tree
 cp_parser_omp_clause_from_to (cp_parser *parser, enum omp_clause_code kind,
@@ -41861,15 +41864,94 @@  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;
 
+  size_t pos = 1, colon_pos = 0;
+  int iterator_length = 0;
+  while (cp_lexer_nth_token_is (parser->lexer, pos, CPP_NAME))
+    {
+      if (cp_lexer_nth_token_is (parser->lexer, pos + 1, CPP_OPEN_PAREN))
+	{
+	  unsigned int n = cp_parser_skip_balanced_tokens (parser, pos + 1);
+	  if (n != pos + 1)
+	    {
+	      iterator_length = n - pos;
+	      pos = n - 1;
+	    }
+	}
+      if (cp_lexer_nth_token_is (parser->lexer, pos + 1, CPP_COMMA))
+	pos += 2;
+      else
+	pos++;
+      if (cp_lexer_nth_token_is (parser->lexer, pos, CPP_COLON))
+	{
+	  colon_pos = pos;
+	  break;
+	}
+    }
+
   bool present = false;
-  cp_token *token = cp_lexer_peek_token (parser->lexer);
+  tree iterators = NULL_TREE;
+  for (pos = 1; pos < colon_pos; pos++)
+    {
+      cp_token *token = cp_lexer_peek_token (parser->lexer);
 
-  if (token->type == CPP_NAME
-      && strcmp (IDENTIFIER_POINTER (token->u.value), "present") == 0
-      && cp_lexer_nth_token_is (parser->lexer, 2, CPP_COLON))
+      if (token->type == CPP_COMMA)
+	{
+	  cp_lexer_consume_token (parser->lexer);
+	  continue;
+	}
+      if (token->type == CPP_NAME)
+	{
+	  const char *name = IDENTIFIER_POINTER (token->u.value);
+	  if (strcmp (name, "present") == 0)
+	    {
+	      if (present)
+		{
+		  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 = true;
+	      cp_lexer_consume_token (parser->lexer);
+	    }
+	  else if (strcmp (name, "iterator") == 0)
+	    {
+	      if (iterators)
+		{
+		  cp_parser_error (parser, "too many %<iterator%> modifiers");
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/true);
+		  return list;
+		}
+	      begin_scope (sk_omp, NULL);
+	      iterators = cp_parser_omp_iterators (parser);
+	      pos += iterator_length - 1;
+	    }
+	  else
+	    {
+	      if (kind == OMP_CLAUSE_TO)
+		cp_parser_error (parser, "%<to%> clause with motion modifier "
+				 "other than %<iterator%> or %<present%>");
+	      else
+		cp_parser_error (parser, "%<from%> clause with motion modifier "
+				 "other than %<iterator%> or %<present%>");
+	      cp_parser_skip_to_closing_parenthesis (parser,
+						     /*recovering=*/true,
+						     /*or_comma=*/false,
+						     /*consume_paren=*/true);
+	      return list;
+	    }
+	}
+    }
+
+  if (colon_pos)
     {
-      present = true;
-      cp_lexer_consume_token (parser->lexer);
+      gcc_assert (pos == colon_pos);
+      gcc_assert (cp_lexer_next_token_is (parser->lexer, CPP_COLON));
       cp_lexer_consume_token (parser->lexer);
     }
 
@@ -41878,6 +41960,19 @@  cp_parser_omp_clause_from_to (cp_parser *parser, enum omp_clause_code kind,
     for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
       OMP_CLAUSE_MOTION_PRESENT (c) = 1;
 
+  if (iterators)
+    {
+      tree block = poplevel (1, 1, 0);
+      if (iterators == error_mark_node)
+	iterators = NULL_TREE;
+      else
+	TREE_VEC_ELT (iterators, 5) = block;
+    }
+
+  if (iterators)
+    for (tree c = nl; c != list; c = OMP_CLAUSE_CHAIN (c))
+      OMP_CLAUSE_ITERATORS (c) = iterators;
+
   return nl;
 }
 
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index ecd0241e88b..cb15f3b40de 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -8594,6 +8594,9 @@  finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	case OMP_CLAUSE_MAP:
 	  if (OMP_CLAUSE_MAP_IMPLICIT (c) && !implicit_moved)
 	    goto move_implicit;
+	  /* FALLTHRU */
+	case OMP_CLAUSE_TO:
+	case OMP_CLAUSE_FROM:
 	  if (OMP_CLAUSE_ITERATORS (c)
 	      && cp_omp_finish_iterators (OMP_CLAUSE_ITERATORS (c)))
 	    {
@@ -8601,8 +8604,6 @@  finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	      break;
 	    }
 	  /* FALLTHRU */
-	case OMP_CLAUSE_TO:
-	case OMP_CLAUSE_FROM:
 	case OMP_CLAUSE__CACHE_:
 	  {
 	    using namespace omp_addr_tokenizer;
diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 1327e07f9a6..0040f1f2167 100644
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -12627,7 +12627,8 @@  error_out:
 static void
 gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 			   enum omp_region_type region_type,
-			   enum tree_code code)
+			   enum tree_code code,
+			   gimple_seq *loops_seq_p = NULL)
 {
   using namespace omp_addr_tokenizer;
   struct gimplify_omp_ctx *ctx, *outer_ctx;
@@ -13366,23 +13367,24 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 	  if (OMP_CLAUSE_SIZE (c) == NULL_TREE)
 	    OMP_CLAUSE_SIZE (c) = DECL_P (decl) ? DECL_SIZE_UNIT (decl)
 				  : TYPE_SIZE_UNIT (TREE_TYPE (decl));
-	  if (gimplify_expr (&OMP_CLAUSE_SIZE (c), pre_p,
-			     NULL, is_gimple_val, fb_rvalue) == GS_ERROR)
+	  gimple_seq *seq_p;
+	  seq_p = enter_omp_iterator_loop_context (c, loops_seq_p, pre_p);
+	  if (gimplify_expr (&OMP_CLAUSE_SIZE (c), seq_p, NULL,
+			     is_gimple_val, fb_rvalue) == GS_ERROR)
 	    {
 	      remove = true;
+	      exit_omp_iterator_loop_context (c);
 	      break;
 	    }
 	  if (!DECL_P (decl))
 	    {
-	      if (gimplify_expr (&OMP_CLAUSE_DECL (c), pre_p,
-				 NULL, is_gimple_lvalue, fb_lvalue)
-		  == GS_ERROR)
-		{
-		  remove = true;
-		  break;
-		}
+	      if (gimplify_expr (&OMP_CLAUSE_DECL (c), seq_p, NULL,
+				 is_gimple_lvalue, fb_lvalue) == GS_ERROR)
+		remove = true;
+	      exit_omp_iterator_loop_context (c);
 	      break;
 	    }
+	  exit_omp_iterator_loop_context (c);
 	  goto do_notice;
 
 	case OMP_CLAUSE_USE_DEVICE_PTR:
@@ -17779,7 +17781,7 @@  gimplify_omp_workshare (tree *expr_p, gimple_seq *pre_p)
   if ((ort & ORT_ACC) == 0)
     in_omp_construct = false;
   gimplify_scan_omp_clauses (&OMP_CLAUSES (expr), pre_p, ort,
-			     TREE_CODE (expr));
+			     TREE_CODE (expr), &iterator_loops_seq);
   if (TREE_CODE (expr) == OMP_TARGET)
     optimize_target_teams (expr, pre_p);
   if ((ort & (ORT_TARGET | ORT_TARGET_DATA)) != 0
@@ -17936,10 +17938,16 @@  gimplify_omp_target_update (tree *expr_p, gimple_seq *pre_p)
     default:
       gcc_unreachable ();
     }
+
+  gimple_seq iterator_loops_seq = NULL;
+  remove_unused_omp_iterator_vars (&OMP_STANDALONE_CLAUSES (expr));
+  build_omp_iterators_loops (&OMP_STANDALONE_CLAUSES (expr),
+			     &iterator_loops_seq);
+
   gimplify_scan_omp_clauses (&OMP_STANDALONE_CLAUSES (expr), pre_p,
-			     ort, TREE_CODE (expr));
+			     ort, TREE_CODE (expr), &iterator_loops_seq);
   gimplify_adjust_omp_clauses (pre_p, NULL, &OMP_STANDALONE_CLAUSES (expr),
-			       TREE_CODE (expr));
+			       TREE_CODE (expr), &iterator_loops_seq);
   if (TREE_CODE (expr) == OACC_UPDATE
       && omp_find_clause (OMP_STANDALONE_CLAUSES (expr),
 			  OMP_CLAUSE_IF_PRESENT))
@@ -18003,7 +18011,8 @@  gimplify_omp_target_update (tree *expr_p, gimple_seq *pre_p)
 	      gcc_unreachable ();
 	    }
     }
-  stmt = gimple_build_omp_target (NULL, kind, OMP_STANDALONE_CLAUSES (expr));
+  stmt = gimple_build_omp_target (NULL, kind, OMP_STANDALONE_CLAUSES (expr),
+				  iterator_loops_seq);
 
   gimplify_seq_add_stmt (pre_p, stmt);
   *expr_p = NULL_TREE;
diff --git a/gcc/testsuite/c-c++-common/gomp/target-update-iterators-1.c b/gcc/testsuite/c-c++-common/gomp/target-update-iterators-1.c
new file mode 100644
index 00000000000..3a64f511da4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/target-update-iterators-1.c
@@ -0,0 +1,20 @@ 
+/* { dg-do compile } */
+/* { dg-options "-fopenmp" } */
+
+#define DIM1 17
+#define DIM2 39
+
+void f (int **x, float **y)
+{
+  #pragma omp target update to (iterator(i=0:DIM1): x[i][:DIM2])
+
+  #pragma omp target update to (iterator(i=0:DIM1): x[i][:DIM2], y[i][:DIM2])
+
+  #pragma omp target update to (iterator(i=0:DIM1), present: x[i][:DIM2])
+
+  #pragma omp target update to (iterator(i=0:DIM1), iterator(j=0:DIM2): x[i][j]) /* { dg-error "too many 'iterator' modifiers" } */
+  /* { dg-error ".#pragma omp target update. must contain at least one .from. or .to. clauses" "" { target *-*-* } .-1 } */
+
+  #pragma omp target update to (iterator(i=0:DIM1), something: x[i][j]) /* { dg-error ".to. clause with motion modifier other than .iterator. or .present. before .something." } */
+  /* { dg-error ".#pragma omp target update. must contain at least one .from. or .to. clauses" "" { target *-*-* } .-1 } */
+}
diff --git a/gcc/testsuite/c-c++-common/gomp/target-update-iterators-2.c b/gcc/testsuite/c-c++-common/gomp/target-update-iterators-2.c
new file mode 100644
index 00000000000..ae0a222485a
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/target-update-iterators-2.c
@@ -0,0 +1,23 @@ 
+/* { dg-do compile } */
+/* { dg-options "-fopenmp -fdump-tree-gimple" } */
+
+void f (int *x, float *y, double *z)
+{
+  #pragma omp target update to(iterator(i=0:10): x) /* { dg-warning "iterator variable .i. not used in clause expression" }*/
+    ;
+
+  #pragma omp target update from(iterator(i2=0:10, j2=0:20): x[i2]) /* { dg-warning "iterator variable .j2. not used in clause expression" }*/
+    ;
+
+  #pragma omp target update to(iterator(i3=0:10, j3=0:20, k3=0:30): x[i3+j3], y[j3+k3], z[k3+i3])
+  /* { dg-warning "iterator variable .i3. not used in clause expression" "" { target *-*-* } .-1 } */
+  /* { dg-warning "iterator variable .j3. not used in clause expression" "" { target *-*-* } .-2 } */
+  /* { dg-warning "iterator variable .k3. not used in clause expression" "" { target *-*-* } .-3 } */
+    ;
+}
+
+/* { dg-final { scan-tree-dump "update to\\\(x " "gimple" } } */
+/* { dg-final { scan-tree-dump "update from\\\(iterator\\\(int i2=0:10:1, loop_label=" "gimple" } } */
+/* { dg-final { scan-tree-dump "to\\\(iterator\\\(int i3=0:10:1, int k3=0:30:1, loop_label=" "gimple" } } */
+/* { dg-final { scan-tree-dump "to\\\(iterator\\\(int j3=0:20:1, int k3=0:30:1, loop_label=" "gimple" } } */
+/* { dg-final { scan-tree-dump "to\\\(iterator\\\(int i3=0:10:1, int j3=0:20:1, loop_label=" "gimple" } } */
diff --git a/gcc/testsuite/c-c++-common/gomp/target-update-iterators-3.c b/gcc/testsuite/c-c++-common/gomp/target-update-iterators-3.c
new file mode 100644
index 00000000000..21b5aa88083
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/target-update-iterators-3.c
@@ -0,0 +1,17 @@ 
+/* { dg-do compile } */
+/* { dg-options "-fopenmp -fdump-tree-gimple" } */
+
+#define DIM1 10
+#define DIM2 20
+#define DIM3 30
+
+void f (int ***x, float ***y, double **z)
+{
+  #pragma omp target update to (iterator(i=0:DIM1, j=0:DIM2): x[i][j][:DIM3], y[i][j][:DIM3])
+  #pragma omp target update from (iterator(i=0:DIM1): z[i][:DIM2])
+}
+
+/* { dg-final { scan-tree-dump-times "if \\(i <= 9\\) goto <D\.\[0-9\]+>; else goto <D\.\[0-9\]+>;" 2 "gimple" } } */
+/* { dg-final { scan-tree-dump-times "if \\(j <= 19\\) goto <D\.\[0-9\]+>; else goto <D\.\[0-9\]+>;" 1 "gimple" } } */
+/* { dg-final { scan-tree-dump-times "to\\(iterator\\(int i=0:10:1, int j=0:20:1, loop_label=<D\.\[0-9\]+>, elems=D\.\[0-9\]+, index=D\.\[0-9\]+\\):\\*D\.\[0-9\]+" 2 "gimple" } } */
+/* { dg-final { scan-tree-dump-times "from\\(iterator\\(int i=0:10:1, loop_label=<D\.\[0-9\]+>, elems=D\.\[0-9\]+, index=D\.\[0-9\]+\\):\\*D\.\[0-9\]+" 1 "gimple" } } */
diff --git a/gcc/tree-pretty-print.cc b/gcc/tree-pretty-print.cc
index 851827b5b0f..ccfdcf5eb91 100644
--- a/gcc/tree-pretty-print.cc
+++ b/gcc/tree-pretty-print.cc
@@ -1190,6 +1190,11 @@  dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
       pp_string (pp, "from(");
       if (OMP_CLAUSE_MOTION_PRESENT (clause))
 	pp_string (pp, "present:");
+      if (OMP_CLAUSE_ITERATORS (clause))
+	{
+	  dump_omp_iterators (pp, OMP_CLAUSE_ITERATORS (clause), spc, flags);
+	  pp_colon (pp);
+	}
       dump_generic_node (pp, OMP_CLAUSE_DECL (clause),
 			 spc, flags, false);
       goto print_clause_size;
@@ -1198,6 +1203,11 @@  dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
       pp_string (pp, "to(");
       if (OMP_CLAUSE_MOTION_PRESENT (clause))
 	pp_string (pp, "present:");
+      if (OMP_CLAUSE_ITERATORS (clause))
+	{
+	  dump_omp_iterators (pp, OMP_CLAUSE_ITERATORS (clause), spc, flags);
+	  pp_colon (pp);
+	}
       dump_generic_node (pp, OMP_CLAUSE_DECL (clause),
 			 spc, flags, false);
       goto print_clause_size;
diff --git a/gcc/tree.cc b/gcc/tree.cc
index 46d04c849cb..e18ec090c1c 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -264,8 +264,8 @@  unsigned const char omp_clause_num_ops[] =
   1, /* OMP_CLAUSE_IS_DEVICE_PTR  */
   1, /* OMP_CLAUSE_INCLUSIVE  */
   1, /* OMP_CLAUSE_EXCLUSIVE  */
-  2, /* OMP_CLAUSE_FROM  */
-  2, /* OMP_CLAUSE_TO  */
+  3, /* OMP_CLAUSE_FROM  */
+  3, /* OMP_CLAUSE_TO  */
   3, /* OMP_CLAUSE_MAP  */
   1, /* OMP_CLAUSE_HAS_DEVICE_ADDR  */
   1, /* OMP_CLAUSE_DOACROSS  */
diff --git a/gcc/tree.h b/gcc/tree.h
index b87432aadbb..28a32a7f8d8 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1634,11 +1634,13 @@  class auto_suppress_location_wrappers
 #define OMP_CLAUSE_LOCATION(NODE)  (OMP_CLAUSE_CHECK (NODE))->omp_clause.locus
 
 #define OMP_CLAUSE_HAS_ITERATORS(NODE) \
-  (OMP_CLAUSE_CODE (NODE) == OMP_CLAUSE_MAP				\
+  ((OMP_CLAUSE_CODE (NODE) == OMP_CLAUSE_FROM				\
+    || OMP_CLAUSE_CODE (NODE) == OMP_CLAUSE_TO				\
+    || OMP_CLAUSE_CODE (NODE) == OMP_CLAUSE_MAP)			\
    && OMP_CLAUSE_ITERATORS (NODE))
 #define OMP_CLAUSE_ITERATORS(NODE) \
   OMP_CLAUSE_OPERAND (OMP_CLAUSE_RANGE_CHECK (OMP_CLAUSE_CHECK (NODE),	\
-					      OMP_CLAUSE_MAP,		\
+					      OMP_CLAUSE_FROM,		\
 					      OMP_CLAUSE_MAP), 2)
 
 /* True on OMP_FOR and other OpenMP/OpenACC looping constructs if the loop nest
diff --git a/libgomp/target.c b/libgomp/target.c
index 463a162879b..60d57a19dd0 100644
--- a/libgomp/target.c
+++ b/libgomp/target.c
@@ -2260,6 +2260,8 @@  gomp_update (struct gomp_device_descr *devicep, size_t mapnum, void **hostaddrs,
   size_t i;
   struct splay_tree_key_s cur_node;
   const int typemask = short_mapkind ? 0xff : 0x7;
+  bool iterators_p = false;
+  size_t *iterator_count = NULL;
 
   if (!devicep)
     return;
@@ -2267,6 +2269,10 @@  gomp_update (struct gomp_device_descr *devicep, size_t mapnum, void **hostaddrs,
   if (mapnum == 0)
     return;
 
+  if (short_mapkind)
+    iterators_p = gomp_merge_iterator_maps (&mapnum, &hostaddrs, &sizes,
+					    &kinds, &iterator_count);
+
   gomp_mutex_lock (&devicep->lock);
   if (devicep->state == GOMP_DEVICE_FINALIZED)
     {
@@ -2360,6 +2366,14 @@  gomp_update (struct gomp_device_descr *devicep, size_t mapnum, void **hostaddrs,
 	  }
       }
   gomp_mutex_unlock (&devicep->lock);
+
+  if (iterators_p)
+    {
+      free (hostaddrs);
+      free (sizes);
+      free (kinds);
+      free (iterator_count);
+    }
 }
 
 static struct gomp_offload_icv_list *
diff --git a/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-1.c b/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-1.c
new file mode 100644
index 00000000000..5a4cad5c219
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-1.c
@@ -0,0 +1,65 @@ 
+/* { dg-do run } */
+
+/* Test target enter data and target update to the target using map
+   iterators.  */
+
+#include <stdlib.h>
+
+#define DIM1 8
+#define DIM2 15
+
+int mkarray (int *x[])
+{
+  int expected = 0;
+  for (int i = 0; i < DIM1; i++)
+    {
+      x[i] = (int *) malloc (DIM2 * sizeof (int));
+      for (int j = 0; j < DIM2; j++)
+	{
+	  x[i][j] = rand ();
+	  expected += x[i][j];
+	}
+    }
+
+  return expected;
+}
+
+int main (void)
+{
+  int *x[DIM1];
+  int sum;
+  int expected = mkarray (x);
+
+  #pragma omp target enter data map(to: x[:DIM1])
+  #pragma omp target enter data map(iterator(i=0:DIM1), to: x[i][:DIM2])
+  #pragma omp target map(from: sum)
+    {
+      sum = 0;
+      for (int i = 0; i < DIM1; i++)
+	for (int j = 0; j < DIM2; j++)
+	  sum += x[i][j];
+    }
+
+  if (sum != expected)
+    return 1;
+
+  expected = 0;
+  for (int i = 0; i < DIM1; i++)
+    for (int j = 0; j < DIM2; j++)
+      {
+	x[i][j] *= rand ();
+	expected += x[i][j];
+      }
+
+  #pragma omp target update to(iterator(i=0:DIM1): x[i][:DIM2])
+
+  #pragma omp target map(from: sum)
+    {
+      sum = 0;
+      for (int i = 0; i < DIM1; i++)
+	for (int j = 0; j < DIM2; j++)
+	  sum += x[i][j];
+    }
+
+  return sum != expected;
+}
diff --git a/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-2.c b/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-2.c
new file mode 100644
index 00000000000..93438d01c97
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-2.c
@@ -0,0 +1,58 @@ 
+/* { dg-do run } */
+/* { dg-require-effective-target offload_device_nonshared_as } */
+
+/* Test target enter data and target update from the target using map
+   iterators.  */
+
+#include <stdlib.h>
+
+#define DIM1 8
+#define DIM2 15
+
+void mkarray (int *x[])
+{
+  for (int i = 0; i < DIM1; i++)
+    {
+      x[i] = (int *) malloc (DIM2 * sizeof (int));
+      for (int j = 0; j < DIM2; j++)
+	x[i][j] = 0;
+    }
+}
+
+int main (void)
+{
+  int *x[DIM1];
+  int sum, expected;
+
+  mkarray (x);
+
+  #pragma omp target enter data map(alloc: x[:DIM1])
+  #pragma omp target enter data map(iterator(i=0:DIM1), to: x[i][:DIM2])
+  #pragma omp target map(from: expected)
+    {
+      expected = 0;
+      for (int i = 0; i < DIM1; i++)
+	for (int j = 0; j < DIM2; j++)
+	  {
+	    x[i][j] = (i + 1) * (j + 2);
+	    expected += x[i][j];
+	  }
+    }
+
+  /* Host copy of x should remain unchanged.  */
+  sum = 0;
+  for (int i = 0; i < DIM1; i++)
+    for (int j = 0; j < DIM2; j++)
+      sum += x[i][j];
+  if (sum != 0)
+    return 1;
+
+  #pragma omp target update from(iterator(i=0:DIM1): x[i][:DIM2])
+
+  /* Host copy should now be updated.  */
+  sum = 0;
+  for (int i = 0; i < DIM1; i++)
+    for (int j = 0; j < DIM2; j++)
+      sum += x[i][j];
+  return sum - expected;
+}
diff --git a/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-3.c b/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-3.c
new file mode 100644
index 00000000000..a70b21c4b75
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c-c++-common/target-update-iterators-3.c
@@ -0,0 +1,67 @@ 
+/* { dg-do run } */
+/* { dg-require-effective-target offload_device_nonshared_as } */
+
+/* Test target enter data and target update to the target using map
+   iterators with a function.  */
+
+#include <stdlib.h>
+
+#define DIM1 8
+#define DIM2 15
+
+void mkarray (int *x[])
+{
+  for (int i = 0; i < DIM1; i++)
+    {
+      x[i] = (int *) malloc (DIM2 * sizeof (int));
+      for (int j = 0; j < DIM2; j++)
+	x[i][j] = rand ();
+    }
+}
+
+int f (int i)
+{
+  return i * 2;
+}
+
+int main (void)
+{
+  int *x[DIM1], x_new[DIM1][DIM2];
+  int sum, expected;
+
+  mkarray (x);
+
+  #pragma omp target enter data map(alloc: x[:DIM1])
+  #pragma omp target enter data map(iterator(i=0:DIM1), to: x[i][:DIM2])
+
+  /* Update x on host.  */
+  for (int i = 0; i < DIM1; i++)
+    for (int j = 0; j < DIM2; j++)
+      {
+	x_new[i][j] = x[i][j];
+	x[i][j] = (i + 1) * (j + 2);
+      }
+
+  /* Update a subset of x on target.  */
+  #pragma omp target update to(iterator(i=0:DIM1/2): x[f (i)][:DIM2])
+
+  #pragma omp target map(from: sum)
+    {
+      sum = 0;
+      for (int i = 0; i < DIM1; i++)
+	for (int j = 0; j < DIM2; j++)
+	  sum += x[i][j];
+    }
+
+  /* Calculate expected value on host.  */
+  for (int i = 0; i < DIM1/2; i++)
+    for (int j = 0; j < DIM2; j++)
+      x_new[f (i)][j] = x[f (i)][j];
+
+  expected = 0;
+  for (int i = 0; i < DIM1; i++)
+    for (int j = 0; j < DIM2; j++)
+      expected += x_new[i][j];
+
+  return sum - expected;
+}