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[PATCH 3/5, OpenACC] Add support for allocatable arrays as optional arguments


This patch allows allocatable arrays passed as Fortran optional
arguments to be used in OpenACC. The GIMPLE code generated by the current lowering unconditionally attempts to access fields within the structure representing the array, resulting in a null dereference if the array is non-present.

This patch generates extra code to test if the argument is null.
If so, it sets the size of the array contents to zero, and the
pointers to data to null. This avoids the null dereferences, prevents libgomp from trying to copy non-existant data, and preserves the null pointer used by PRESENT to detect non-present arguments.

	gcc/fortran/
	* trans-openmp.c (gfc_build_conditional_assign): New.
	(gfc_build_conditional_assign_expr): New.
	(gfc_omp_finish_clause): Add conditionals to set the clause
	declaration to null and size to zero if the declaration is a
	non-present optional argument.
	(gfc_trans_omp_clauses): Likewise.
---
gcc/fortran/trans-openmp.c | 164 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 138 insertions(+), 26 deletions(-)

diff --git a/gcc/fortran/trans-openmp.c b/gcc/fortran/trans-openmp.c
index 8eae7bc..8bfeeeb 100644
--- a/gcc/fortran/trans-openmp.c
+++ b/gcc/fortran/trans-openmp.c
@@ -1067,6 +1067,62 @@ gfc_omp_clause_dtor (tree clause, tree decl)
   return tem;
 }

+/* Build a conditional expression in BLOCK.  If COND_VAL is not
+   null, then the block THEN_B is executed, otherwise ELSE_VAL
+   is assigned to VAL.  */
+
+static void
+gfc_build_conditional_assign (stmtblock_t *block,
+			      tree val,
+			      tree cond_val,
+			      tree then_b,
+			      tree else_val)
+{
+  stmtblock_t cond_block;
+  tree cond, else_b;
+  tree val_ty = TREE_TYPE (val);
+
+  gfc_init_block (&cond_block);
+  gfc_add_modify (&cond_block, val, fold_convert (val_ty, else_val));
+  else_b = gfc_finish_block (&cond_block);
+  cond = fold_convert (pvoid_type_node, cond_val);
+  cond = fold_build2_loc (input_location, NE_EXPR,
+			  logical_type_node,
+			  cond, null_pointer_node);
+  gfc_add_expr_to_block (block,
+			 build3_loc (input_location,
+				     COND_EXPR,
+				     void_type_node,
+				     cond, then_b,
+				     else_b));
+}
+
+/* Build a conditional expression in BLOCK, returning a temporary
+   variable containing the result.  If COND_VAL is not null, then
+   THEN_VAL will be assigned to the variable, otherwise ELSE_VAL
+   is assigned.
+ */
+
+static tree
+gfc_build_conditional_assign_expr (stmtblock_t *block,
+				   tree cond_val,
+				   tree then_val,
+				   tree else_val)
+{
+  tree val;
+  tree val_ty = TREE_TYPE (then_val);
+  stmtblock_t cond_block;
+
+  val = create_tmp_var (val_ty);
+
+  gfc_init_block (&cond_block);
+  gfc_add_modify (&cond_block, val, then_val);
+  tree then_b = gfc_finish_block (&cond_block);
+
+  gfc_build_conditional_assign (block, val, cond_val, then_b, else_val);
+
+  return val;
+}

 void
 gfc_omp_finish_clause (tree c, gimple_seq *pre_p)
@@ -1124,17 +1180,46 @@ gfc_omp_finish_clause (tree c, gimple_seq *pre_p)
       stmtblock_t block;
       gfc_start_block (&block);
       tree type = TREE_TYPE (decl);
-      tree ptr = gfc_conv_descriptor_data_get (decl);
+      bool optional_arg_p =
+	        TREE_CODE (decl) == INDIRECT_REF
+	      && TREE_CODE (TREE_OPERAND (decl, 0)) == PARM_DECL
+	      && DECL_BY_REFERENCE (TREE_OPERAND (decl, 0))
+	      && TREE_CODE (TREE_TYPE (TREE_OPERAND (decl, 0))) == POINTER_TYPE;
+      tree ptr;
+
+      if (optional_arg_p)
+	ptr = gfc_build_conditional_assign_expr (
+		&block,
+		TREE_OPERAND (decl, 0),
+		gfc_conv_descriptor_data_get (decl),
+		null_pointer_node);
+      else
+	ptr = gfc_conv_descriptor_data_get (decl);
       ptr = fold_convert (build_pointer_type (char_type_node), ptr);
       ptr = build_fold_indirect_ref (ptr);
       OMP_CLAUSE_DECL (c) = ptr;
       c2 = build_omp_clause (input_location, OMP_CLAUSE_MAP);
       OMP_CLAUSE_SET_MAP_KIND (c2, GOMP_MAP_TO_PSET);
-      OMP_CLAUSE_DECL (c2) = decl;
+      if (optional_arg_p)
+	{
+	  ptr = create_tmp_var (TREE_TYPE (TREE_OPERAND (decl, 0)));
+	  gfc_add_modify (&block, ptr, TREE_OPERAND (decl, 0));
+
+	  OMP_CLAUSE_DECL (c2) = build_fold_indirect_ref (ptr);
+	}
+      else
+	OMP_CLAUSE_DECL (c2) = decl;
       OMP_CLAUSE_SIZE (c2) = TYPE_SIZE_UNIT (type);
       c3 = build_omp_clause (OMP_CLAUSE_LOCATION (c), OMP_CLAUSE_MAP);
       OMP_CLAUSE_SET_MAP_KIND (c3, GOMP_MAP_POINTER);
-      OMP_CLAUSE_DECL (c3) = gfc_conv_descriptor_data_get (decl);
+      if (optional_arg_p)
+	OMP_CLAUSE_DECL (c3) = gfc_build_conditional_assign_expr (
+		&block,
+		TREE_OPERAND (decl, 0),
+		gfc_conv_descriptor_data_get (decl),
+		null_pointer_node);
+      else
+	OMP_CLAUSE_DECL (c3) = gfc_conv_descriptor_data_get (decl);
       OMP_CLAUSE_SIZE (c3) = size_int (0);
       tree size = create_tmp_var (gfc_array_index_type);
       tree elemsz = TYPE_SIZE_UNIT (gfc_get_element_type (type));
@@ -1165,6 +1250,27 @@ gfc_omp_finish_clause (tree c, gimple_seq *pre_p)
 						     void_type_node, cond,
 						     then_b, else_b));
 	}
+      else if (optional_arg_p)
+	{
+	  stmtblock_t cond_block;
+	  tree then_b;
+
+	  gfc_init_block (&cond_block);
+	  gfc_add_modify (&cond_block, size,
+			  gfc_full_array_size (&cond_block, decl,
+					       GFC_TYPE_ARRAY_RANK (type)));
+	  gfc_add_modify (&cond_block, size,
+			  fold_build2 (MULT_EXPR, gfc_array_index_type,
+				       size, elemsz));
+	  then_b = gfc_finish_block (&cond_block);
+
+	  gfc_build_conditional_assign (
+		  &block,
+		  size,
+		  TREE_OPERAND (decl, 0),
+		  then_b,
+		  build_int_cst (gfc_array_index_type, 0));
+	}
       else
 	{
 	  gfc_add_modify (&block, size,
@@ -2171,7 +2277,17 @@ gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,
 		  if (GFC_DESCRIPTOR_TYPE_P (TREE_TYPE (decl)))
 		    {
 		      tree type = TREE_TYPE (decl);
-		      tree ptr = gfc_conv_descriptor_data_get (decl);
+		      tree ptr;
+
+		      if (n->sym->attr.optional)
+			ptr = gfc_build_conditional_assign_expr (
+				block,
+				TREE_OPERAND (decl, 0),
+				gfc_conv_descriptor_data_get (decl),
+				null_pointer_node);
+		      else
+			ptr = gfc_conv_descriptor_data_get (decl);
+
 		      ptr = fold_convert (build_pointer_type (char_type_node),
 					  ptr);
 		      ptr = build_fold_indirect_ref (ptr);
@@ -2190,34 +2306,30 @@ gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,

 		      /* We have to check for n->sym->attr.dimension because
 			 of scalar coarrays.  */
-		      if (n->sym->attr.pointer && n->sym->attr.dimension)
+		      if ((n->sym->attr.pointer || n->sym->attr.optional)
+			  && n->sym->attr.dimension)
 			{
 			  stmtblock_t cond_block;
 			  tree size
 			    = gfc_create_var (gfc_array_index_type, NULL);
-			  tree tem, then_b, else_b, zero, cond;
+			  tree cond = n->sym->attr.optional
+			      ? TREE_OPERAND (decl, 0)
+			      : gfc_conv_descriptor_data_get (decl);

 			  gfc_init_block (&cond_block);
-			  tem
-			    = gfc_full_array_size (&cond_block, decl,
-						   GFC_TYPE_ARRAY_RANK (type));
-			  gfc_add_modify (&cond_block, size, tem);
-			  then_b = gfc_finish_block (&cond_block);
-			  gfc_init_block (&cond_block);
-			  zero = build_int_cst (gfc_array_index_type, 0);
-			  gfc_add_modify (&cond_block, size, zero);
-			  else_b = gfc_finish_block (&cond_block);
-			  tem = gfc_conv_descriptor_data_get (decl);
-			  tem = fold_convert (pvoid_type_node, tem);
-			  cond = fold_build2_loc (input_location, NE_EXPR,
-						  logical_type_node,
-						  tem, null_pointer_node);
-			  gfc_add_expr_to_block (block,
-						 build3_loc (input_location,
-							     COND_EXPR,
-							     void_type_node,
-							     cond, then_b,
-							     else_b));
+			  gfc_add_modify (&cond_block, size,
+					  gfc_full_array_size (
+					      &cond_block, decl,
+					      GFC_TYPE_ARRAY_RANK (type)));
+			  tree then_b = gfc_finish_block (&cond_block);
+
+			  gfc_build_conditional_assign (
+				  block,
+				  size,
+				  cond,
+				  then_b,
+				  build_int_cst (gfc_array_index_type, 0));
+
 			  OMP_CLAUSE_SIZE (node) = size;
 			}
 		      else if (n->sym->attr.dimension)
--
2.8.1



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