Introduce and use attribute::unsigned_constant

This introduces a new 'unsigned_constant' method on attribute.  This
method can be used to get the value as an unsigned number.  Unsigned
scalar forms are handled, and signed scalar forms are handled as well
provided that the value is non-negative.

Several spots in the reader that expect small DWARF-defined constants
are updated to use this new method.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32680
Approved-By: Simon Marchi <simon.marchi@efficios.com>

1 files changed, 49 insertions, 22 deletions

diff --git a/gdb/dwarf2/attribute.c b/gdb/dwarf2/attribute.c
index 3eb32b6..49c0bc0 100644
--- a/gdb/dwarf2/attribute.c
+++ b/gdb/dwarf2/attribute.c
@@ -164,6 +164,27 @@ attribute::constant_value (int default_value) const
 
 /* See attribute.h.  */
 
+std::optional<ULONGEST>
+attribute::unsigned_constant () const
+{
+  if (form_is_strictly_signed ())
+    {
+      if (u.snd >= 0)
+	return u.snd;
+      complaint (_("Attribute value is not unsigned (%s)"),
+		 dwarf_form_name (form));
+    }
+  else if (form_is_constant ())
+    return u.unsnd;
+
+  /* For DW_FORM_data16 see attribute::form_is_constant.  */
+  complaint (_("Attribute value is not a constant (%s)"),
+	     dwarf_form_name (form));
+  return {};
+}
+
+/* See attribute.h.  */
+
 bool
 attribute::form_is_unsigned () const
 {
@@ -216,21 +237,24 @@ attribute::form_requires_reprocessing () const
 dwarf_defaulted_attribute
 attribute::defaulted () const
 {
-  LONGEST value = constant_value (-1);
+  std::optional<ULONGEST> value = unsigned_constant ();
 
-  switch (value)
+  if (value.has_value ())
     {
-    case DW_DEFAULTED_no:
-    case DW_DEFAULTED_in_class:
-    case DW_DEFAULTED_out_of_class:
-      return (dwarf_defaulted_attribute) value;
+      switch (*value)
+	{
+	case DW_DEFAULTED_no:
+	case DW_DEFAULTED_in_class:
+	case DW_DEFAULTED_out_of_class:
+	  return (dwarf_defaulted_attribute) *value;
+
+	default:
+	  complaint (_("unrecognized DW_AT_defaulted value (%s)"),
+		     plongest (*value));
+	  break;
+	}
     }
 
-  /* If the form was not constant, we already complained in
-     constant_value, so there's no need to complain again.  */
-  if (form_is_constant ())
-    complaint (_("unrecognized DW_AT_defaulted value (%s)"),
-	       plongest (value));
   return DW_DEFAULTED_no;
 }
 
@@ -239,21 +263,24 @@ attribute::defaulted () const
 dwarf_virtuality_attribute
 attribute::as_virtuality () const
 {
-  LONGEST value = constant_value (-1);
+  std::optional<ULONGEST> value = unsigned_constant ();
 
-  switch (value)
+  if (value.has_value ())
     {
-    case DW_VIRTUALITY_none:
-    case DW_VIRTUALITY_virtual:
-    case DW_VIRTUALITY_pure_virtual:
-      return (dwarf_virtuality_attribute) value;
+      switch (*value)
+	{
+	case DW_VIRTUALITY_none:
+	case DW_VIRTUALITY_virtual:
+	case DW_VIRTUALITY_pure_virtual:
+	  return (dwarf_virtuality_attribute) *value;
+
+	default:
+	  complaint (_("unrecognized DW_AT_virtuality value (%s)"),
+		     plongest (*value));
+	  break;
+	}
     }
 
-  /* If the form was not constant, we already complained in
-     constant_value, so there's no need to complain again.  */
-  if (form_is_constant ())
-    complaint (_("unrecognized DW_AT_virtuality value (%s)"),
-	       plongest (value));
   return DW_VIRTUALITY_none;
 }