DWARF: create a macro for max dimensions for array descr. lang. hook

The array descriptor language hook can hold the description of a limited
number of array dimensions.  This macro will ease preventing overflow in
front-ends.

gcc/ada/ChangeLog:

	* gcc-interface/misc.c (gnat_get_array_descr_info): When the
	array has more dimensions than the language hook can handle,
	fall back to a nested arrays description.  Handle context-less
	array types.

gcc/ChangeLog:

	* dwarf2out.h (DWARF2OUT_ARRAY_DESCR_INFO_MAX_DIMEN): New macro.
	(struct array_descr_info): Use it for the dimensions array's
	size.
	* dwarf2out.c (gen_type_die_with_usage): Check that the array
	descr. language hook does not return an array with more
	dimensions that it should.

From-SVN: r231766

5 files changed, 38 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 964b0a3..9736786 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,14 @@
 2015-12-17  Pierre-Marie de Rodat  <derodat@adacore.com>
 
+	* dwarf2out.h (DWARF2OUT_ARRAY_DESCR_INFO_MAX_DIMEN): New macro.
+	(struct array_descr_info): Use it for the dimensions array's
+	size.
+	* dwarf2out.c (gen_type_die_with_usage): Check that the array
+	descr. language hook does not return an array with more
+	dimensions that it should.
+
+2015-12-17  Pierre-Marie de Rodat  <derodat@adacore.com>
+
 	* langhooks.h (struct lang_hooks_for_types): Add a
 	get_fixed_point_type_info field.
 	* langhooks-def.h (LANG_HOOKS_GET_FIXED_POINT_TYPE_INFO): New
diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog
index 4cf3fe4..eb10923 100644
--- a/gcc/ada/ChangeLog
+++ b/gcc/ada/ChangeLog
@@ -1,5 +1,12 @@
 2015-12-17  Pierre-Marie de Rodat  <derodat@adacore.com>
 
+	* gcc-interface/misc.c (gnat_get_array_descr_info): When the
+	array has more dimensions than the language hook can handle,
+	fall back to a nested arrays description.  Handle context-less
+	array types.
+
+2015-12-17  Pierre-Marie de Rodat  <derodat@adacore.com>
+
 	* gcc-interface/decl.c (gnat_to_gnu_entity): When
 	-fgnat-encodings-minimal, do not add ___XUP/XUT suffixes to type
 	names and do not generate ___XA parallel types.
diff --git a/gcc/ada/gcc-interface/misc.c b/gcc/ada/gcc-interface/misc.c
index 279e5fc..891ca3f 100644
--- a/gcc/ada/gcc-interface/misc.c
+++ b/gcc/ada/gcc-interface/misc.c
@@ -856,7 +856,20 @@ gnat_get_array_descr_info (const_tree type, struct array_descr_info *info)
 	break;
       last_dimen = dimen;
     }
+
   info->ndimensions = i;
+
+  /* Too many dimensions?  Give up generating proper description: yield instead
+     nested arrays.  Note that in this case, this hook is invoked once on each
+     intermediate array type: be consistent and output nested arrays for all
+     dimensions.  */
+  if (info->ndimensions > DWARF2OUT_ARRAY_DESCR_INFO_MAX_DIMEN
+      || TYPE_MULTI_ARRAY_P (first_dimen))
+    {
+      info->ndimensions = 1;
+      last_dimen = first_dimen;
+    }
+
   info->element_type = TREE_TYPE (last_dimen);
 
   /* Now iterate over all dimensions in source-order and fill the info
@@ -881,7 +894,8 @@ gnat_get_array_descr_info (const_tree type, struct array_descr_info *info)
 	     expressions:  arrays that are constrained by record discriminants
 	     and XUA types.  */
 	  const bool is_xua_type =
-	   (TREE_CODE (TYPE_CONTEXT (first_dimen)) != RECORD_TYPE
+	   (TYPE_CONTEXT (first_dimen) != NULL_TREE
+            && TREE_CODE (TYPE_CONTEXT (first_dimen)) != RECORD_TYPE
 	    && contains_placeholder_p (TYPE_MIN_VALUE (index_type)));
 
 	  if (is_xua_type && gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL)
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 538b76d..98528c7 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -22563,6 +22563,10 @@ gen_type_die_with_usage (tree type, dw_die_ref context_die,
       memset (&info, 0, sizeof (info));
       if (lang_hooks.types.get_array_descr_info (type, &info))
 	{
+	  /* Fortran sometimes emits array types with no dimension.  */
+	  gcc_assert (info.ndimensions >= 0
+		      && (info.ndimensions
+			  <= DWARF2OUT_ARRAY_DESCR_INFO_MAX_DIMEN));
 	  gen_descr_array_type_die (type, &info, context_die);
 	  TREE_ASM_WRITTEN (type) = 1;
 	  return;
diff --git a/gcc/dwarf2out.h b/gcc/dwarf2out.h
index 9173076..24a384c 100644
--- a/gcc/dwarf2out.h
+++ b/gcc/dwarf2out.h
@@ -316,6 +316,8 @@ enum array_descr_ordering
   array_descr_ordering_column_major
 };
 
+#define DWARF2OUT_ARRAY_DESCR_INFO_MAX_DIMEN 16
+
 struct array_descr_info
 {
   int ndimensions;
@@ -339,7 +341,7 @@ struct array_descr_info
       /* Only Fortran uses more than one dimension for array types.  For other
 	 languages, the stride can be rather specified for the whole array.  */
       tree stride;
-    } dimen[10];
+    } dimen[DWARF2OUT_ARRAY_DESCR_INFO_MAX_DIMEN];
 };
 
 enum fixed_point_scale_factor