[OpenACC,4/7] host_data construct (middle end)

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index ab9e540..0c32219 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -93,6 +93,8 @@  enum gimplify_omp_var_data
 
   GOVD_MAP_0LEN_ARRAY = 32768,
 
+  GOVD_USE_DEVICE = 65536,
+
   GOVD_DATA_SHARE_CLASS = (GOVD_SHARED | GOVD_PRIVATE | GOVD_FIRSTPRIVATE
 			   | GOVD_LASTPRIVATE | GOVD_REDUCTION | GOVD_LINEAR
 			   | GOVD_LOCAL)
@@ -116,7 +118,9 @@  enum omp_region_type
   ORT_COMBINED_TARGET = 33,
   /* Dummy OpenMP region, used to disable expansion of
      DECL_VALUE_EXPRs in taskloop pre body.  */
-  ORT_NONE = 64
+  ORT_NONE = 64,
+  /* An OpenACC host-data region.  */
+  ORT_HOST_DATA = 128
 };
 
 /* Gimplify hashtable helper.  */
@@ -6338,6 +6342,10 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 		decl = TREE_OPERAND (decl, 0);
 	    }
 	  goto do_add_decl;
+	case OMP_CLAUSE_USE_DEVICE:
+	  flags = GOVD_USE_DEVICE | GOVD_EXPLICIT;
+	  check_non_private = "use_device";
+	  goto do_add;
 	case OMP_CLAUSE_LINEAR:
 	  if (gimplify_expr (&OMP_CLAUSE_LINEAR_STEP (c), pre_p, NULL,
 			     is_gimple_val, fb_rvalue) == GS_ERROR)
@@ -7005,7 +7013,6 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 	  break;
 
 	case OMP_CLAUSE_DEVICE_RESIDENT:
-	case OMP_CLAUSE_USE_DEVICE:
 	case OMP_CLAUSE_INDEPENDENT:
 	  remove = true;
 	  break;
@@ -7529,6 +7536,127 @@  gimplify_oacc_cache (tree *expr_p, gimple_seq *pre_p)
   *expr_p = NULL_TREE;
 }
 
+static tree
+gimplify_oacc_host_data_1 (tree *tp, int *walk_subtrees,
+			   void *data ATTRIBUTE_UNUSED)
+{
+  splay_tree_node n = NULL;
+  location_t loc = EXPR_LOCATION (*tp);
+
+  switch (TREE_CODE (*tp))
+    {
+    case ADDR_EXPR:
+      {
+	tree decl = TREE_OPERAND (*tp, 0);
+
+	switch (TREE_CODE (decl))
+	  {
+	  case ARRAY_REF:
+	  case ARRAY_RANGE_REF:
+	  case COMPONENT_REF:
+	  case VIEW_CONVERT_EXPR:
+	  case REALPART_EXPR:
+	  case IMAGPART_EXPR:
+	    if (TREE_CODE (TREE_OPERAND (decl, 0)) == VAR_DECL)
+	      n = splay_tree_lookup (gimplify_omp_ctxp->variables,
+				     (splay_tree_key) TREE_OPERAND (decl, 0));
+	    break;
+
+	  case VAR_DECL:
+	    n = splay_tree_lookup (gimplify_omp_ctxp->variables,
+				   (splay_tree_key) decl);
+	    break;
+
+	  default:
+	    ;
+	  }
+
+	if (n != NULL && (n->value & GOVD_USE_DEVICE) != 0)
+	  {
+	    tree t = builtin_decl_explicit (BUILT_IN_GOACC_DEVICEPTR);
+	    *tp = build_call_expr_loc (loc, t, 1, *tp);
+	  }
+
+	*walk_subtrees = 0;
+      }
+      break;
+
+    case VAR_DECL:
+      {
+	tree decl = *tp;
+
+	n = splay_tree_lookup (gimplify_omp_ctxp->variables,
+			       (splay_tree_key) decl);
+
+	if (n != NULL && (n->value & GOVD_USE_DEVICE) != 0)
+	  {
+	    if (!POINTER_TYPE_P (TREE_TYPE (decl)))
+	      return decl;
+
+	    tree t = builtin_decl_explicit (BUILT_IN_GOACC_DEVICEPTR);
+	    *tp = build_call_expr_loc (loc, t, 1, *tp);
+	    *walk_subtrees = 0;
+	  }
+      }
+      break;
+
+    case OACC_PARALLEL:
+    case OACC_KERNELS:
+    case OACC_LOOP:
+      *walk_subtrees = 0;
+      break;
+
+    default:
+      ;
+    }
+
+  return NULL_TREE;
+}
+
+static enum gimplify_status
+gimplify_oacc_host_data (tree *expr_p, gimple_seq *pre_p)
+{
+  tree expr = *expr_p, orig_body;
+  gimple_seq body = NULL;
+
+  gimplify_scan_omp_clauses (&OACC_HOST_DATA_CLAUSES (expr), pre_p,
+			     ORT_HOST_DATA, OACC_HOST_DATA);
+
+  orig_body = OACC_HOST_DATA_BODY (expr);
+
+  /* Perform a pre-pass over the host_data region's body, inserting calls to
+     GOACC_deviceptr where appropriate.  */
+
+  tree ret = walk_tree_without_duplicates (&orig_body,
+					   &gimplify_oacc_host_data_1, 0);
+
+  if (ret)
+    {
+      error_at (EXPR_LOCATION (expr),
+		"undefined use of variable %qE in host_data region",
+		DECL_NAME (ret));
+      gimplify_adjust_omp_clauses (pre_p, &OACC_HOST_DATA_CLAUSES (expr),
+				   OACC_HOST_DATA);
+      return GS_ERROR;
+    }
+
+  push_gimplify_context ();
+
+  gimple *g = gimplify_and_return_first (orig_body, &body);
+
+  if (gimple_code (g) == GIMPLE_BIND)
+    pop_gimplify_context (g);
+  else
+    pop_gimplify_context (NULL);
+
+  gimplify_adjust_omp_clauses (pre_p, &OACC_HOST_DATA_CLAUSES (expr),
+			       OACC_HOST_DATA);
+
+  gimplify_seq_add_stmt (pre_p, g);
+
+  return GS_ALL_DONE;
+}
+
 /* Gimplify the contents of an OMP_PARALLEL statement.  This involves
    gimplification of the body, as well as scanning the body for used
    variables.  We need to do this scan now, because variable-sized
@@ -9595,6 +9723,9 @@  gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
 	  break;
 
 	case OACC_HOST_DATA:
+	  ret = gimplify_oacc_host_data (expr_p, pre_p);
+	  break;
+
 	case OACC_DECLARE:
 	  sorry ("directive not yet implemented");
 	  ret = GS_ALL_DONE;
diff --git a/gcc/omp-builtins.def b/gcc/omp-builtins.def
index ea9cf0d..9ed075f 100644
--- a/gcc/omp-builtins.def
+++ b/gcc/omp-builtins.def
@@ -47,6 +47,8 @@  DEF_GOACC_BUILTIN (BUILT_IN_GOACC_UPDATE, "GOACC_update",
 DEF_GOACC_BUILTIN (BUILT_IN_GOACC_WAIT, "GOACC_wait",
 		   BT_FN_VOID_INT_INT_VAR,
 		   ATTR_NOTHROW_LIST)
+DEF_GOACC_BUILTIN (BUILT_IN_GOACC_DEVICEPTR, "GOACC_deviceptr",
+		   BT_FN_PTR_PTR, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GOACC_BUILTIN (BUILT_IN_GOACC_GET_THREAD_NUM, "GOACC_get_thread_num",
 		   BT_FN_INT, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GOACC_BUILTIN (BUILT_IN_GOACC_GET_NUM_THREADS, "GOACC_get_num_threads",