[08/13] OpenACC 2.6 deep copy: middle-end parts

This patch has been broken out of the "OpenACC 2.6 manual deep copy
support" patch, last posted here:

  https://gcc.gnu.org/ml/gcc-patches/2019-11/msg02376.html

This part contains the middle-end support for OpenACC 2.6 attach and
detach operations, either as standalone clauses or as "attach/detach"
actions triggered by other (data movement) clauses, as detailed in the
specification.

Tested alongside other patches in this series with offloading to
NVPTX. OK?

Thanks,

Julian

ChangeLog

	gcc/
	* gimplify.c (gimplify_omp_var_data): Add GOVD_MAP_HAS_ATTACHMENTS.
	(insert_struct_comp_map): Support derived-type member mappings
	for arrays with descriptors which use GOMP_MAP_TO_PSET.  Support
	GOMP_MAP_ATTACH_DETACH.
	(gimplify_scan_omp_clauses): Tidy up OACC_ENTER_DATA/OACC_EXIT_DATA
	mappings.  Handle attach/detach clauses and component references.
	(gimplify_adjust_omp_clauses_1): Skip adjustments for explicit
	attach/detach clauses.
	(gimplify_omp_target_update): Handle finalize for detach.
	* omp-low.c (lower_omp_target): Support GOMP_MAP_ATTACH,
	GOMP_MAP_DETACH, GOMP_MAP_FORCE_DETACH.
	* tree-pretty-print.c (dump_omp_clause): Likewise, plus
	GOMP_MAP_ATTACH_DETACH.

	include/
	* gomp-constants.h (gomp_map_kind): Add GOMP_MAP_ATTACH_DETACH.
---
 gcc/gimplify.c           | 232 ++++++++++++++++++++++++++++++++++-----
 gcc/omp-low.c            |   3 +
 gcc/tree-pretty-print.c  |  18 +++
 include/gomp-constants.h |   6 +-
 4 files changed, 229 insertions(+), 30 deletions(-)

Hi!

On 2019-12-17T22:03:48-0800, Julian Brown <julian@codesourcery.com> wrote:
> This part contains the middle-end support for OpenACC 2.6 attach and
> detach operations, either as standalone clauses or as "attach/detach"
> actions triggered by other (data movement) clauses, as detailed in the
> specification.

As mentioned in <https://gcc.gnu.org/PR93026>, "that commit [r279626] is
doing more than just the OpenACC 2.6 manual deep copy changes; see the
'gcc/gimplify.c' changes related to the PR92929 discussion" etc. (see
<https://gcc.gnu.org/PR92929>).  See attached "[PR93026, PR92929] Adjust
'gfortran.dg/goacc/finalize-1.f' for r279626 changes"; committed to trunk
in r279700.


Grüße
 Thomas


> ChangeLog
>
> 	gcc/
> 	* gimplify.c (gimplify_omp_var_data): Add GOVD_MAP_HAS_ATTACHMENTS.
> 	(insert_struct_comp_map): Support derived-type member mappings
> 	for arrays with descriptors which use GOMP_MAP_TO_PSET.  Support
> 	GOMP_MAP_ATTACH_DETACH.
> 	(gimplify_scan_omp_clauses): Tidy up OACC_ENTER_DATA/OACC_EXIT_DATA
> 	mappings.  Handle attach/detach clauses and component references.
> 	(gimplify_adjust_omp_clauses_1): Skip adjustments for explicit
> 	attach/detach clauses.
> 	(gimplify_omp_target_update): Handle finalize for detach.
> 	* omp-low.c (lower_omp_target): Support GOMP_MAP_ATTACH,
> 	GOMP_MAP_DETACH, GOMP_MAP_FORCE_DETACH.
> 	* tree-pretty-print.c (dump_omp_clause): Likewise, plus
> 	GOMP_MAP_ATTACH_DETACH.
>
> 	include/
> 	* gomp-constants.h (gomp_map_kind): Add GOMP_MAP_ATTACH_DETACH.
> ---
>  gcc/gimplify.c           | 232 ++++++++++++++++++++++++++++++++++-----
>  gcc/omp-low.c            |   3 +
>  gcc/tree-pretty-print.c  |  18 +++
>  include/gomp-constants.h |   6 +-
>  4 files changed, 229 insertions(+), 30 deletions(-)
>
> diff --git a/gcc/gimplify.c b/gcc/gimplify.c
> index e3088dcbe05..e3d5bc83c4f 100644
> --- a/gcc/gimplify.c
> +++ b/gcc/gimplify.c
> @@ -123,6 +123,10 @@ enum gimplify_omp_var_data
>    /* Flag for GOVD_REDUCTION: inscan seen in {in,ex}clusive clause.  */
>    GOVD_REDUCTION_INSCAN = 0x2000000,
>  
> +  /* Flag for GOVD_MAP: (struct) vars that have pointer attachments for
> +     fields.  */
> +  GOVD_MAP_HAS_ATTACHMENTS = 8388608,
> +
>    GOVD_DATA_SHARE_CLASS = (GOVD_SHARED | GOVD_PRIVATE | GOVD_FIRSTPRIVATE
>  			   | GOVD_LASTPRIVATE | GOVD_REDUCTION | GOVD_LINEAR
>  			   | GOVD_LOCAL)
> @@ -8209,20 +8213,33 @@ insert_struct_comp_map (enum tree_code code, tree c, tree struct_node,
>  			tree prev_node, tree *scp)
>  {
>    enum gomp_map_kind mkind
> -    = code == OMP_TARGET_EXIT_DATA ? GOMP_MAP_RELEASE : GOMP_MAP_ALLOC;
> +    = (code == OMP_TARGET_EXIT_DATA || code == OACC_EXIT_DATA)
> +      ? GOMP_MAP_RELEASE : GOMP_MAP_ALLOC;
>  
>    tree c2 = build_omp_clause (OMP_CLAUSE_LOCATION (c), OMP_CLAUSE_MAP);
>    tree cl = scp ? prev_node : c2;
>    OMP_CLAUSE_SET_MAP_KIND (c2, mkind);
>    OMP_CLAUSE_DECL (c2) = unshare_expr (OMP_CLAUSE_DECL (c));
>    OMP_CLAUSE_CHAIN (c2) = scp ? *scp : prev_node;
> -  OMP_CLAUSE_SIZE (c2) = TYPE_SIZE_UNIT (ptr_type_node);
> +  if (OMP_CLAUSE_CHAIN (prev_node) != c
> +      && OMP_CLAUSE_CODE (OMP_CLAUSE_CHAIN (prev_node)) == OMP_CLAUSE_MAP
> +      && (OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (prev_node))
> +	  == GOMP_MAP_TO_PSET))
> +    OMP_CLAUSE_SIZE (c2) = OMP_CLAUSE_SIZE (OMP_CLAUSE_CHAIN (prev_node));
> +  else
> +    OMP_CLAUSE_SIZE (c2) = TYPE_SIZE_UNIT (ptr_type_node);
>    if (struct_node)
>      OMP_CLAUSE_CHAIN (struct_node) = c2;
>  
>    /* We might need to create an additional mapping if we have a reference to a
> -     pointer (in C++).  */
> -  if (OMP_CLAUSE_CHAIN (prev_node) != c)
> +     pointer (in C++).  Don't do this if we have something other than a
> +     GOMP_MAP_ALWAYS_POINTER though, i.e. a GOMP_MAP_TO_PSET.  */
> +  if (OMP_CLAUSE_CHAIN (prev_node) != c
> +      && OMP_CLAUSE_CODE (OMP_CLAUSE_CHAIN (prev_node)) == OMP_CLAUSE_MAP
> +      && ((OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (prev_node))
> +	   == GOMP_MAP_ALWAYS_POINTER)
> +	  || (OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (prev_node))
> +	      == GOMP_MAP_ATTACH_DETACH)))
>      {
>        tree c4 = OMP_CLAUSE_CHAIN (prev_node);
>        tree c3 = build_omp_clause (OMP_CLAUSE_LOCATION (c), OMP_CLAUSE_MAP);
> @@ -8329,6 +8346,7 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>    struct gimplify_omp_ctx *ctx, *outer_ctx;
>    tree c;
>    hash_map<tree, tree> *struct_map_to_clause = NULL;
> +  hash_set<tree> *struct_deref_set = NULL;
>    tree *prev_list_p = NULL, *orig_list_p = list_p;
>    int handled_depend_iterators = -1;
>    int nowait = -1;
> @@ -8731,8 +8749,6 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  	    case OMP_TARGET_DATA:
>  	    case OMP_TARGET_ENTER_DATA:
>  	    case OMP_TARGET_EXIT_DATA:
> -	    case OACC_ENTER_DATA:
> -	    case OACC_EXIT_DATA:
>  	    case OACC_HOST_DATA:
>  	      if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_FIRSTPRIVATE_POINTER
>  		  || (OMP_CLAUSE_MAP_KIND (c)
> @@ -8741,6 +8757,15 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  		   mapped, but not the pointer to it.  */
>  		remove = true;
>  	      break;
> +	    case OACC_ENTER_DATA:
> +	    case OACC_EXIT_DATA:
> +	      if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_POINTER
> +		  || OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_TO_PSET
> +		  || OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_FIRSTPRIVATE_POINTER
> +		  || (OMP_CLAUSE_MAP_KIND (c)
> +		      == GOMP_MAP_FIRSTPRIVATE_REFERENCE))
> +		remove = true;
> +	      break;
>  	    default:
>  	      break;
>  	    }
> @@ -8814,7 +8839,35 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  		  pd = &TREE_OPERAND (decl, 0);
>  		  decl = TREE_OPERAND (decl, 0);
>  		}
> -	      if (TREE_CODE (decl) == COMPONENT_REF)
> +	      bool indir_p = false;
> +	      tree orig_decl = decl;
> +	      tree decl_ref = NULL_TREE;
> +	      if ((region_type & ORT_ACC) != 0
> +		  && TREE_CODE (*pd) == COMPONENT_REF
> +		  && OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_ATTACH_DETACH
> +		  && code != OACC_UPDATE)
> +		{
> +		  while (TREE_CODE (decl) == COMPONENT_REF)
> +		    {
> +		      decl = TREE_OPERAND (decl, 0);
> +		      if ((TREE_CODE (decl) == MEM_REF
> +			   && integer_zerop (TREE_OPERAND (decl, 1)))
> +			  || INDIRECT_REF_P (decl))
> +			{
> +			  indir_p = true;
> +			  decl = TREE_OPERAND (decl, 0);
> +			}
> +		      if (TREE_CODE (decl) == INDIRECT_REF
> +			  && DECL_P (TREE_OPERAND (decl, 0))
> +			  && (TREE_CODE (TREE_TYPE (TREE_OPERAND (decl, 0)))
> +			      == REFERENCE_TYPE))
> +			{
> +			  decl_ref = decl;
> +			  decl = TREE_OPERAND (decl, 0);
> +			}
> +		    }
> +		}
> +	      else if (TREE_CODE (decl) == COMPONENT_REF)
>  		{
>  		  while (TREE_CODE (decl) == COMPONENT_REF)
>  		    decl = TREE_OPERAND (decl, 0);
> @@ -8824,13 +8877,76 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  			  == REFERENCE_TYPE))
>  		    decl = TREE_OPERAND (decl, 0);
>  		}
> +	      if (decl != orig_decl && DECL_P (decl) && indir_p)
> +		{
> +		  gomp_map_kind k = (code == OACC_EXIT_DATA) ? GOMP_MAP_DETACH
> +							     : GOMP_MAP_ATTACH;
> +		  /* We have a dereference of a struct member.  Make this an
> +		     attach/detach operation, and ensure the base pointer is
> +		     mapped as a FIRSTPRIVATE_POINTER.  */
> +		  OMP_CLAUSE_SET_MAP_KIND (c, k);
> +		  flags = GOVD_MAP | GOVD_SEEN | GOVD_EXPLICIT;
> +		  tree next_clause = OMP_CLAUSE_CHAIN (c);
> +		  if (k == GOMP_MAP_ATTACH
> +		      && code != OACC_ENTER_DATA
> +		      && (!next_clause
> +			   || (OMP_CLAUSE_CODE (next_clause) != OMP_CLAUSE_MAP)
> +			   || (OMP_CLAUSE_MAP_KIND (next_clause)
> +			       != GOMP_MAP_POINTER)
> +			   || OMP_CLAUSE_DECL (next_clause) != decl)
> +		      && (!struct_deref_set
> +			  || !struct_deref_set->contains (decl)))
> +		    {
> +		      if (!struct_deref_set)
> +			struct_deref_set = new hash_set<tree> ();
> +		      /* As well as the attach, we also need a
> +			 FIRSTPRIVATE_POINTER clause to properly map the
> +			 pointer to the struct base.  */
> +		      tree c2 = build_omp_clause (OMP_CLAUSE_LOCATION (c),
> +						  OMP_CLAUSE_MAP);
> +		      OMP_CLAUSE_SET_MAP_KIND (c2, GOMP_MAP_ALLOC);
> +		      OMP_CLAUSE_MAP_MAYBE_ZERO_LENGTH_ARRAY_SECTION (c2)
> +			= 1;
> +		      tree charptr_zero
> +			= build_int_cst (build_pointer_type (char_type_node),
> +					 0);
> +		      OMP_CLAUSE_DECL (c2)
> +			= build2 (MEM_REF, char_type_node,
> +				  decl_ref ? decl_ref : decl, charptr_zero);
> +		      OMP_CLAUSE_SIZE (c2) = size_zero_node;
> +		      tree c3 = build_omp_clause (OMP_CLAUSE_LOCATION (c),
> +						  OMP_CLAUSE_MAP);
> +		      OMP_CLAUSE_SET_MAP_KIND (c3,
> +					       GOMP_MAP_FIRSTPRIVATE_POINTER);
> +		      OMP_CLAUSE_DECL (c3) = decl;
> +		      OMP_CLAUSE_SIZE (c3) = size_zero_node;
> +		      tree mapgrp = *prev_list_p;
> +		      *prev_list_p = c2;
> +		      OMP_CLAUSE_CHAIN (c3) = mapgrp;
> +		      OMP_CLAUSE_CHAIN (c2) = c3;
> +
> +		      struct_deref_set->add (decl);
> +		    }
> +		  goto do_add_decl;
> +		}
> +	      /* An "attach/detach" operation on an update directive should
> +		 behave as a GOMP_MAP_ALWAYS_POINTER.  Beware that
> +		 unlike attach or detach map kinds, GOMP_MAP_ALWAYS_POINTER
> +		 depends on the previous mapping.  */
> +	      if (code == OACC_UPDATE
> +		  && OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_ATTACH_DETACH)
> +		OMP_CLAUSE_SET_MAP_KIND (c, GOMP_MAP_ALWAYS_POINTER);
>  	      if (gimplify_expr (pd, pre_p, NULL, is_gimple_lvalue, fb_lvalue)
>  		  == GS_ERROR)
>  		{
>  		  remove = true;
>  		  break;
>  		}
> -	      if (DECL_P (decl))
> +	      if (DECL_P (decl)
> +		  && OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_TO_PSET
> +		  && OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_ATTACH
> +		  && OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_DETACH
> +		  && code != OACC_UPDATE)
>  		{
>  		  if (error_operand_p (decl))
>  		    {
> @@ -8851,7 +8967,8 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  		      break;
>  		    }
>  
> -		  if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_ALWAYS_POINTER)
> +		  if (OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_ALWAYS_POINTER
> +		      || OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_ATTACH_DETACH)
>  		    {
>  		      /* Error recovery.  */
>  		      if (prev_list_p == NULL)
> @@ -8884,20 +9001,47 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  		    = splay_tree_lookup (ctx->variables, (splay_tree_key)decl);
>  		  bool ptr = (OMP_CLAUSE_MAP_KIND (c)
>  			      == GOMP_MAP_ALWAYS_POINTER);
> +		  bool attach_detach = (OMP_CLAUSE_MAP_KIND (c)
> +					== GOMP_MAP_ATTACH_DETACH);
> +		  bool attach = OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_ATTACH
> +				|| OMP_CLAUSE_MAP_KIND (c) == GOMP_MAP_DETACH;
> +		  bool has_attachments = false;
> +		  /* For OpenACC, pointers in structs should trigger an
> +		     attach action.  */
> +		  if (attach_detach && (region_type & ORT_ACC) != 0)
> +		    {
> +		      /* Turn a GOMP_MAP_ATTACH_DETACH clause into a
> +			 GOMP_MAP_ATTACH or GOMP_MAP_DETACH clause after we
> +			 have detected a case that needs a GOMP_MAP_STRUCT
> +			 mapping added.  */
> +		      gomp_map_kind k
> +			= (code == OACC_EXIT_DATA) ? GOMP_MAP_DETACH
> +						   : GOMP_MAP_ATTACH;
> +		      OMP_CLAUSE_SET_MAP_KIND (c, k);
> +		      has_attachments = true;
> +		    }
>  		  if (n == NULL || (n->value & GOVD_MAP) == 0)
>  		    {
>  		      tree l = build_omp_clause (OMP_CLAUSE_LOCATION (c),
>  						 OMP_CLAUSE_MAP);
> -		      OMP_CLAUSE_SET_MAP_KIND (l, GOMP_MAP_STRUCT);
> +		      gomp_map_kind k = attach ? GOMP_MAP_FORCE_PRESENT
> +					       : GOMP_MAP_STRUCT;
> +
> +		      OMP_CLAUSE_SET_MAP_KIND (l, k);
>  		      if (base_ref)
>  			OMP_CLAUSE_DECL (l) = unshare_expr (base_ref);
>  		      else
>  			OMP_CLAUSE_DECL (l) = decl;
> -		      OMP_CLAUSE_SIZE (l) = size_int (1);
> +		      OMP_CLAUSE_SIZE (l)
> +			= (!attach
> +			   ? size_int (1)
> +			   : DECL_P (OMP_CLAUSE_DECL (l))
> +			   ? DECL_SIZE_UNIT (OMP_CLAUSE_DECL (l))
> +			   : TYPE_SIZE_UNIT (TREE_TYPE (OMP_CLAUSE_DECL (l))));
>  		      if (struct_map_to_clause == NULL)
>  			struct_map_to_clause = new hash_map<tree, tree>;
>  		      struct_map_to_clause->put (decl, l);
> -		      if (ptr)
> +		      if (ptr || attach_detach)
>  			{
>  			  insert_struct_comp_map (code, c, l, *prev_list_p,
>  						  NULL);
> @@ -8923,23 +9067,31 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  			  OMP_CLAUSE_CHAIN (l) = c2;
>  			}
>  		      flags = GOVD_MAP | GOVD_EXPLICIT;
> -		      if (GOMP_MAP_ALWAYS_P (OMP_CLAUSE_MAP_KIND (c)) || ptr)
> +		      if (GOMP_MAP_ALWAYS_P (OMP_CLAUSE_MAP_KIND (c))
> +			  || ptr
> +			  || attach_detach)
>  			flags |= GOVD_SEEN;
> +		      if (has_attachments)
> +			flags |= GOVD_MAP_HAS_ATTACHMENTS;
>  		      goto do_add_decl;
>  		    }
> -		  else
> +		  else if (struct_map_to_clause)
>  		    {
>  		      tree *osc = struct_map_to_clause->get (decl);
>  		      tree *sc = NULL, *scp = NULL;
> -		      if (GOMP_MAP_ALWAYS_P (OMP_CLAUSE_MAP_KIND (c)) || ptr)
> +		      if (GOMP_MAP_ALWAYS_P (OMP_CLAUSE_MAP_KIND (c))
> +			  || ptr
> +			  || attach_detach)
>  			n->value |= GOVD_SEEN;
>  		      sc = &OMP_CLAUSE_CHAIN (*osc);
>  		      if (*sc != c
>  			  && (OMP_CLAUSE_MAP_KIND (*sc)
> -			      == GOMP_MAP_FIRSTPRIVATE_REFERENCE)) 
> +			      == GOMP_MAP_FIRSTPRIVATE_REFERENCE))
>  			sc = &OMP_CLAUSE_CHAIN (*sc);
> +		      /* Here "prev_list_p" is the end of the inserted
> +			 alloc/release nodes after the struct node, OSC.  */
>  		      for (; *sc != c; sc = &OMP_CLAUSE_CHAIN (*sc))
> -			if (ptr && sc == prev_list_p)
> +			if ((ptr || attach_detach) && sc == prev_list_p)
>  			  break;
>  			else if (TREE_CODE (OMP_CLAUSE_DECL (*sc))
>  				 != COMPONENT_REF
> @@ -8992,7 +9144,7 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  				|| (known_eq (offset1, offsetn)
>  				    && maybe_lt (bitpos1, bitposn)))
>  			      {
> -				if (ptr)
> +				if (ptr || attach_detach)
>  				  scp = sc;
>  				else
>  				  break;
> @@ -9000,10 +9152,11 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  			  }
>  		      if (remove)
>  			break;
> -		      OMP_CLAUSE_SIZE (*osc)
> -			= size_binop (PLUS_EXPR, OMP_CLAUSE_SIZE (*osc),
> -				      size_one_node);
> -		      if (ptr)
> +		      if (!attach)
> +			OMP_CLAUSE_SIZE (*osc)
> +			  = size_binop (PLUS_EXPR, OMP_CLAUSE_SIZE (*osc),
> +					size_one_node);
> +		      if (ptr || attach_detach)
>  			{
>  			  tree cl = insert_struct_comp_map (code, c, NULL,
>  							    *prev_list_p, scp);
> @@ -9033,11 +9186,18 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>  		}
>  	      if (!remove
>  		  && OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_ALWAYS_POINTER
> +		  && OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_ATTACH_DETACH
> +		  && OMP_CLAUSE_MAP_KIND (c) != GOMP_MAP_TO_PSET
>  		  && OMP_CLAUSE_CHAIN (c)
>  		  && OMP_CLAUSE_CODE (OMP_CLAUSE_CHAIN (c)) == OMP_CLAUSE_MAP
> -		  && (OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (c))
> -		      == GOMP_MAP_ALWAYS_POINTER))
> +		  && ((OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (c))
> +		       == GOMP_MAP_ALWAYS_POINTER)
> +		      || (OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (c))
> +			  == GOMP_MAP_ATTACH_DETACH)
> +		      || (OMP_CLAUSE_MAP_KIND (OMP_CLAUSE_CHAIN (c))
> +			  == GOMP_MAP_TO_PSET)))
>  		prev_list_p = list_p;
> +
>  	      break;
>  	    }
>  	  flags = GOVD_MAP | GOVD_EXPLICIT;
> @@ -9561,6 +9721,8 @@ gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
>    gimplify_omp_ctxp = ctx;
>    if (struct_map_to_clause)
>      delete struct_map_to_clause;
> +  if (struct_deref_set)
> +    delete struct_deref_set;
>  }
>  
>  /* Return true if DECL is a candidate for shared to firstprivate
> @@ -9708,6 +9870,8 @@ gimplify_adjust_omp_clauses_1 (splay_tree_node n, void *data)
>      return 0;
>    if ((flags & GOVD_SEEN) == 0)
>      return 0;
> +  if ((flags & GOVD_MAP_HAS_ATTACHMENTS) != 0)
> +    return 0;
>    if (flags & GOVD_DEBUG_PRIVATE)
>      {
>        gcc_assert ((flags & GOVD_DATA_SHARE_CLASS) == GOVD_SHARED);
> @@ -12762,8 +12926,9 @@ gimplify_omp_target_update (tree *expr_p, gimple_seq *pre_p)
>  	   && omp_find_clause (OMP_STANDALONE_CLAUSES (expr),
>  			       OMP_CLAUSE_FINALIZE))
>      {
> -      /* Use GOMP_MAP_DELETE/GOMP_MAP_FORCE_FROM to denote that "finalize"
> -	 semantics apply to all mappings of this OpenACC directive.  */
> +      /* Use GOMP_MAP_DELETE, GOMP_MAP_FORCE_DETACH, and
> +	 GOMP_MAP_FORCE_FROM to denote that "finalize" semantics apply
> +	 to all mappings of this OpenACC directive.  */
>        bool finalize_marked = false;
>        for (tree c = OMP_STANDALONE_CLAUSES (expr); c; c = OMP_CLAUSE_CHAIN (c))
>  	if (OMP_CLAUSE_CODE (c) == OMP_CLAUSE_MAP)
> @@ -12777,10 +12942,19 @@ gimplify_omp_target_update (tree *expr_p, gimple_seq *pre_p)
>  	      OMP_CLAUSE_SET_MAP_KIND (c, GOMP_MAP_DELETE);
>  	      finalize_marked = true;
>  	      break;
> +	    case GOMP_MAP_DETACH:
> +	      OMP_CLAUSE_SET_MAP_KIND (c, GOMP_MAP_FORCE_DETACH);
> +	      finalize_marked = true;
> +	      break;
> +	    case GOMP_MAP_STRUCT:
> +	    case GOMP_MAP_FORCE_PRESENT:
> +	      /* Skip over an initial struct or force_present mapping.  */
> +	      break;
>  	    default:
> -	      /* Check consistency: libgomp relies on the very first data
> -		 mapping clause being marked, so make sure we did that before
> -		 any other mapping clauses.  */
> +	      /* Check consistency: libgomp relies on the very first
> +		 non-struct, non-force-present data mapping clause being
> +		 marked, so make sure we did that before any other mapping
> +		 clauses.  */
>  	      gcc_assert (finalize_marked);
>  	      break;
>  	    }
> diff --git a/gcc/omp-low.c b/gcc/omp-low.c
> index d422c205836..3eb7815449a 100644
> --- a/gcc/omp-low.c
> +++ b/gcc/omp-low.c
> @@ -11439,6 +11439,9 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
>  	  case GOMP_MAP_FORCE_DEVICEPTR:
>  	  case GOMP_MAP_DEVICE_RESIDENT:
>  	  case GOMP_MAP_LINK:
> +	  case GOMP_MAP_ATTACH:
> +	  case GOMP_MAP_DETACH:
> +	  case GOMP_MAP_FORCE_DETACH:
>  	    gcc_assert (is_gimple_omp_oacc (stmt));
>  	    break;
>  	  default:
> diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c
> index 1cf7a912133..379858d0f1f 100644
> --- a/gcc/tree-pretty-print.c
> +++ b/gcc/tree-pretty-print.c
> @@ -849,6 +849,18 @@ dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
>  	case GOMP_MAP_LINK:
>  	  pp_string (pp, "link");
>  	  break;
> +	case GOMP_MAP_ATTACH:
> +	  pp_string (pp, "attach");
> +	  break;
> +	case GOMP_MAP_DETACH:
> +	  pp_string (pp, "detach");
> +	  break;
> +	case GOMP_MAP_FORCE_DETACH:
> +	  pp_string (pp, "force_detach");
> +	  break;
> +	case GOMP_MAP_ATTACH_DETACH:
> +	  pp_string (pp, "attach_detach");
> +	  break;
>  	default:
>  	  gcc_unreachable ();
>  	}
> @@ -870,6 +882,12 @@ dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
>  	    case GOMP_MAP_TO_PSET:
>  	      pp_string (pp, " [pointer set, len: ");
>  	      break;
> +	    case GOMP_MAP_ATTACH:
> +	    case GOMP_MAP_DETACH:
> +	    case GOMP_MAP_FORCE_DETACH:
> +	    case GOMP_MAP_ATTACH_DETACH:
> +	      pp_string (pp, " [bias: ");
> +	      break;
>  	    default:
>  	      pp_string (pp, " [len: ");
>  	      break;
> diff --git a/include/gomp-constants.h b/include/gomp-constants.h
> index e8bd52e81bd..f40d6069582 100644
> --- a/include/gomp-constants.h
> +++ b/include/gomp-constants.h
> @@ -142,7 +142,11 @@ enum gomp_map_kind
>      /* Do not map, but pointer assign a pointer instead.  */
>      GOMP_MAP_FIRSTPRIVATE_POINTER =	(GOMP_MAP_LAST | 1),
>      /* Do not map, but pointer assign a reference instead.  */
> -    GOMP_MAP_FIRSTPRIVATE_REFERENCE =	(GOMP_MAP_LAST | 2)
> +    GOMP_MAP_FIRSTPRIVATE_REFERENCE =	(GOMP_MAP_LAST | 2),
> +    /* An attach or detach operation.  Rewritten to the appropriate type during
> +       gimplification, depending on directive (i.e. "enter data" or
> +       parallel/kernels region vs. "exit data").  */
> +    GOMP_MAP_ATTACH_DETACH =		(GOMP_MAP_LAST | 3)
>    };
>  
>  #define GOMP_MAP_COPY_TO_P(X) \