Base support for <unavailable> value contents.

	gdb/
	* value.h (value_bytes_available): Declare.
	(mark_value_bytes_unavailable): Declare.
	* value.c (struct range): New struct.
	(range_s): New typedef.
	(ranges_overlap): New function.
	(range_lessthan): New function.
	(ranges_contain_p): New function.
	(struct value) <unavailable>: New field.
	(value_bytes_available): New function.
	(mark_value_bytes_unavailable): New function.
	(require_not_optimized_out): Constify parameter.
	(require_available): New function.
	(value_contents_all, value_contents): Require all bytes be
	available.
	(value_free): Free `unavailable'.
	(value_copy): Copy `unavailable'.
	* valprint.h (val_print_unavailable): Declare.
	* valprint.c (valprint_check_validity): Rename `offset' parameter
	to `embedded_offset'.  If printing a scalar, check whether the
	value chunk is available.
	(val_print_unavailable): New.
	(val_print_scalar_formatted): Check whether the value is
	available.
	* python/py-prettyprint.c (apply_val_pretty_printer): Refuse
	pretty-printing unavailable values.

1 files changed, 18 insertions, 4 deletions

diff --git a/gdb/valprint.c b/gdb/valprint.c
index b32d6fca5e5..64a4b05f527 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -260,7 +260,7 @@ scalar_type_p (struct type *type)
 static int
 valprint_check_validity (struct ui_file *stream,
 			 struct type *type,
-			 int offset,
+			 int embedded_offset,
 			 const struct value *val)
 {
   CHECK_TYPEDEF (type);
@@ -269,19 +269,25 @@ valprint_check_validity (struct ui_file *stream,
       && TYPE_CODE (type) != TYPE_CODE_STRUCT
       && TYPE_CODE (type) != TYPE_CODE_ARRAY)
     {
-      if (! value_bits_valid (val, TARGET_CHAR_BIT * offset,
-			      TARGET_CHAR_BIT * TYPE_LENGTH (type)))
+      if (!value_bits_valid (val, TARGET_CHAR_BIT * embedded_offset,
+			     TARGET_CHAR_BIT * TYPE_LENGTH (type)))
 	{
 	  val_print_optimized_out (stream);
 	  return 0;
 	}
 
-      if (value_bits_synthetic_pointer (val, TARGET_CHAR_BIT * offset,
+      if (value_bits_synthetic_pointer (val, TARGET_CHAR_BIT * embedded_offset,
 					TARGET_CHAR_BIT * TYPE_LENGTH (type)))
 	{
 	  fputs_filtered (_("<synthetic pointer>"), stream);
 	  return 0;
 	}
+
+      if (!value_bytes_available (val, embedded_offset, TYPE_LENGTH (type)))
+	{
+	  val_print_unavailable (stream);
+	  return 0;
+	}
     }
 
   return 1;
@@ -293,6 +299,12 @@ val_print_optimized_out (struct ui_file *stream)
   fprintf_filtered (stream, _("<optimized out>"));
 }
 
+void
+val_print_unavailable (struct ui_file *stream)
+{
+  fprintf_filtered (stream, _("<unavailable>"));
+}
+
 /* Print using the given LANGUAGE the data of type TYPE located at
    VALADDR + EMBEDDED_OFFSET (within GDB), which came from the
    inferior at address ADDRESS + EMBEDDED_OFFSET, onto stdio stream
@@ -560,6 +572,8 @@ val_print_scalar_formatted (struct type *type,
   if (!value_bits_valid (val, TARGET_CHAR_BIT * embedded_offset,
 			      TARGET_CHAR_BIT * TYPE_LENGTH (type)))
     val_print_optimized_out (stream);
+  else if (!value_bytes_available (val, embedded_offset, TYPE_LENGTH (type)))
+    val_print_unavailable (stream);
   else
     print_scalar_formatted (valaddr + embedded_offset, type,
 			    options, size, stream);