Use attribute::unsigned_constant for DW_AT_data_bit_offset

This changes the DWARF reader to use attribute::unsigned_constant when
examining DW_AT_data_bit_offset.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32680

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 8941643a1f79e9961733191f9fe0ddba495732b6..4a142fe11bfb8a9315bdc6285a0114de9e755a00 100644 (file)
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -9941,7 +9941,7 @@ handle_member_location (struct die_info *die, struct dwarf2_cu *cu,
       attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
       if (attr != nullptr)
        {
-         *offset = attr->constant_value (0);
+         *offset = attr->unsigned_constant ().value_or (0);
          return 1;
        }
     }
@@ -10012,7 +10012,7 @@ handle_member_location (struct die_info *die, struct dwarf2_cu *cu,
     {
       attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
       if (attr != nullptr)
-       field->set_loc_bitpos (attr->constant_value (0));
+       field->set_loc_bitpos (attr->unsigned_constant ().value_or (0));
     }
 }
 
@@ -10090,6 +10090,7 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
       attr = dwarf2_attr (die, DW_AT_bit_offset, cu);
       if (attr != nullptr && attr->form_is_constant ())
        {
+         ULONGEST bit_offset = attr->unsigned_constant ().value_or (0);
          if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG)
            {
              /* For big endian bits, the DW_AT_bit_offset gives the
@@ -10097,7 +10098,7 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
                 anonymous object to the MSB of the field.  We don't
                 have to do anything special since we don't need to
                 know the size of the anonymous object.  */
-             fp->set_loc_bitpos (fp->loc_bitpos () + attr->constant_value (0));
+             fp->set_loc_bitpos (fp->loc_bitpos () + bit_offset);
            }
          else
            {
@@ -10108,7 +10109,6 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
                 the field itself.  The result is the bit offset of
                 the LSB of the field.  */
              int anonymous_size;
-             int bit_offset = attr->constant_value (0);
 
              attr = dwarf2_attr (die, DW_AT_byte_size, cu);
              if (attr != nullptr && attr->form_is_constant ())
@@ -13773,17 +13773,23 @@ read_base_type (struct die_info *die, struct dwarf2_cu *cu)
            {
              attr = dwarf2_attr (die, DW_AT_data_bit_offset, cu);
              /* Only use the attributes if they make sense together.  */
-             if (attr == nullptr
-                 || (attr->form_is_constant ()
-                     && attr->constant_value (0) >= 0
-                     && (attr->constant_value (0) + real_bit_size
-                         <= 8 * type->length ())))
+             std::optional<ULONGEST> bit_offset;
+             if (attr == nullptr)
+               bit_offset = 0;
+             else if (attr->form_is_constant ())
+               {
+                 bit_offset = attr->unsigned_constant ();
+                 if (bit_offset.has_value ()
+                     && *bit_offset + real_bit_size > 8 * type->length ())
+                   bit_offset.reset ();
+               }
+             if (bit_offset.has_value ())
                {
                  TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_size
                    = real_bit_size;
                  if (attr != nullptr)
                    TYPE_MAIN_TYPE (type)->type_specific.int_stuff.bit_offset
-                     = attr->constant_value (0);
+                     = *bit_offset;
                }
            }
        }