vla: support for DW_AT_count

This patch adds support for DW_AT_count as requested in the code review:

  https://sourceware.org/ml/gdb-patches/2013-11/msg00200.html

gdb/ChangeLog:

	* dwarf2read.c (read_subrange_type): Convert DW_AT_count to a dynamic
	property and store it as the high bound and flag the range accordingly.
	* gdbtypes.c (resolve_dynamic_bounds): If range is flagged as
	RANGE_UPPER_BOUND_IS_COUNT assign low + high - 1 as the new high bound.
	* gdbtypes.h (enum range_flags): New enum.
	(struct range_bounds): Add flags member.

gdb/ChangeLog

@@ -1,3 +1,12 @@
+2014-04-14  Sanimir Agovic  <sanimir.agovic@intel.com>
+
+	* dwarf2read.c (read_subrange_type): Convert DW_AT_count to a dynamic
+	property and store it as the high bound and flag the range accordingly.
+	* gdbtypes.c (resolve_dynamic_bounds): If range is flagged as
+	RANGE_UPPER_BOUND_IS_COUNT assign low + high - 1 as the new high bound.
+	* gdbtypes.h (enum range_flags): New enum.
+	(struct range_bounds): Add flags member.
+
 2014-04-14  Sanimir Agovic  <sanimir.agovic@intel.com>
 
 	* c-typeprint.c (c_type_print_varspec_suffix): Added

gdb/dwarf2read.c

@@ -14493,6 +14493,7 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
   struct attribute *attr;
   struct dynamic_prop low, high;
   int low_default_is_valid;
+  int high_bound_is_count = 0;
   const char *name;
   LONGEST negative_mask;
 
@@ -14559,15 +14560,13 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
   if (!attr_to_dynamic_prop (attr, die, cu, &high))
     {
       attr = dwarf2_attr (die, DW_AT_count, cu);
-      if (attr)
+      if (attr_to_dynamic_prop (attr, die, cu, &high))
 	{
-	  int count = dwarf2_get_attr_constant_value (attr, 1);
-	  high.data.const_val = low.data.const_val + count - 1;
-	}
-      else
-	{
-	  /* Unspecified array length.  */
-	  high.data.const_val = low.data.const_val - 1;
+	  /* If bounds are constant do the final calculation here.  */
+	  if (low.kind == PROP_CONST && high.kind == PROP_CONST)
+	    high.data.const_val = low.data.const_val + high.data.const_val - 1;
+	  else
+	    high_bound_is_count = 1;
 	}
     }
 
@@ -14627,6 +14626,9 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
 
   range_type = create_range_type (NULL, orig_base_type, &low, &high);
 
+  if (high_bound_is_count)
+    TYPE_RANGE_DATA (range_type)->flag_upper_bound_is_count = 1;
+
   /* Ada expects an empty array on no boundary attributes.  */
   if (attr == NULL && cu->language != language_ada)
     TYPE_HIGH_BOUND_KIND (range_type) = PROP_UNDEFINED;

gdb/gdbtypes.c

@@ -1698,6 +1698,10 @@ resolve_dynamic_bounds (struct type *type, CORE_ADDR addr)
     {
       high_bound.kind = PROP_CONST;
       high_bound.data.const_val = value;
+
+      if (TYPE_RANGE_DATA (range_type)->flag_upper_bound_is_count)
+	high_bound.data.const_val
+	  = low_bound.data.const_val + high_bound.data.const_val - 1;
     }
   else
     {

gdb/gdbtypes.h

@@ -663,6 +663,11 @@ struct main_type
       /* * High bound of range.  */
 
       struct dynamic_prop high;
+
+      /* True if HIGH range bound contains the number of elements in the
+	 subrange. This affects how the final hight bound is computed.  */
+
+      int flag_upper_bound_is_count : 1;
     } *bounds;
 
   } flds_bnds;