1 files changed, 139 insertions, 112 deletions

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 55cf02f..2523ca8 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -622,15 +622,21 @@ struct variant_field
   /* A variant can contain other variant parts.  */
   std::vector<variant_part_builder> variant_parts;
 
-  /* If we see a DW_TAG_variant, then this will be set if this is the
-     default branch.  */
-  bool default_branch = false;
   /* If we see a DW_AT_discr_value, then this will be the discriminant
-     value.  */
-  ULONGEST discriminant_value = 0;
+     value.  Just the attribute is stored here, because we have to
+     defer deciding whether the value is signed or unsigned until the
+     end.  */
+  const attribute *discriminant_attr = nullptr;
   /* If we see a DW_AT_discr_list, then this is a pointer to the list
      data.  */
   struct dwarf_block *discr_list_data = nullptr;
+
+  /* If both DW_AT_discr_value and DW_AT_discr_list are absent, then
+     this is the default branch.  */
+  bool is_default () const
+  {
+    return discriminant_attr == nullptr && discr_list_data == nullptr;
+  }
 };
 
 /* This represents a DW_TAG_variant_part.  */
@@ -1282,7 +1288,7 @@ dwarf2_has_info (struct objfile *objfile,
 	 BFD, to avoid races.  */
       try
 	{
-	  dwarf2_read_dwz_file (per_objfile);
+	  dwz_file::read_dwz_file (per_objfile);
 	}
       catch (const gdb_exception_error &err)
 	{
@@ -3896,11 +3902,13 @@ cutu_reader::skip_one_attribute (dwarf_form form, const gdb_byte *info_ptr)
     case DW_FORM_data4:
     case DW_FORM_ref4:
     case DW_FORM_strx4:
+    case DW_FORM_ref_sup4:
       return info_ptr + 4;
 
     case DW_FORM_data8:
     case DW_FORM_ref8:
     case DW_FORM_ref_sig8:
+    case DW_FORM_ref_sup8:
       return info_ptr + 8;
 
     case DW_FORM_data16:
@@ -3913,6 +3921,7 @@ cutu_reader::skip_one_attribute (dwarf_form form, const gdb_byte *info_ptr)
     case DW_FORM_sec_offset:
     case DW_FORM_strp:
     case DW_FORM_GNU_strp_alt:
+    case DW_FORM_strp_sup:
       return info_ptr + m_cu->header.offset_size;
 
     case DW_FORM_exprloc:
@@ -5023,7 +5032,7 @@ process_imported_unit_die (struct die_info *die, struct dwarf2_cu *cu)
   if (attr != NULL)
     {
       sect_offset sect_off = attr->get_ref_die_offset ();
-      bool is_dwz = (attr->form == DW_FORM_GNU_ref_alt || cu->per_cu->is_dwz);
+      bool is_dwz = attr->form_is_alt () || cu->per_cu->is_dwz;
       dwarf2_per_objfile *per_objfile = cu->per_objfile;
       dwarf2_per_cu *per_cu
 	= dwarf2_find_containing_comp_unit (sect_off, is_dwz,
@@ -9920,7 +9929,7 @@ handle_member_location (struct die_info *die, struct dwarf2_cu *cu,
 	 so if we see it, we can assume that a constant form is really
 	 a constant and not a section offset.  */
       if (attr->form_is_constant ())
-	*offset = attr->constant_value (0);
+	*offset = attr->unsigned_constant ().value_or (0);
       else if (attr->form_is_section_offset ())
 	dwarf2_complex_location_expr_complaint ();
       else if (attr->form_is_block ()
@@ -9938,7 +9947,7 @@ 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;
 	}
     }
@@ -9960,7 +9969,7 @@ handle_member_location (struct die_info *die, struct dwarf2_cu *cu,
     {
       if (attr->form_is_constant ())
 	{
-	  LONGEST offset = attr->constant_value (0);
+	  LONGEST offset = attr->unsigned_constant ().value_or (0);
 
 	  /* Work around this GCC 11 bug, where it would erroneously use -1
 	     data member locations, instead of 0:
@@ -10009,7 +10018,7 @@ 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));
     }
 }
 
@@ -10078,7 +10087,7 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
       /* Get bit size of field (zero if none).  */
       attr = dwarf2_attr (die, DW_AT_bit_size, cu);
       if (attr != nullptr)
-	fp->set_bitsize (attr->constant_value (0));
+	fp->set_bitsize (attr->unsigned_constant ().value_or (0));
       else
 	fp->set_bitsize (0);
 
@@ -10087,6 +10096,7 @@ 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
@@ -10094,7 +10104,7 @@ 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
 	    {
@@ -10105,7 +10115,6 @@ 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 ())
@@ -10113,7 +10122,7 @@ dwarf2_add_field (struct field_info *fip, struct die_info *die,
 		  /* The size of the anonymous object containing
 		     the bit field is explicit, so use the
 		     indicated size (in bytes).  */
-		  anonymous_size = attr->constant_value (0);
+		  anonymous_size = attr->unsigned_constant ().value_or (0);
 		}
 	      else
 		{
@@ -10266,13 +10275,19 @@ convert_variant_range (struct obstack *obstack, const variant_field &variant,
 {
   std::vector<discriminant_range> ranges;
 
-  if (variant.default_branch)
+  if (variant.is_default ())
     return {};
 
   if (variant.discr_list_data == nullptr)
     {
-      discriminant_range r
-	= {variant.discriminant_value, variant.discriminant_value};
+      ULONGEST value;
+
+      if (is_unsigned)
+	value = variant.discriminant_attr->unsigned_constant ().value_or (0);
+      else
+	value = variant.discriminant_attr->signed_constant ().value_or (0);
+
+      discriminant_range r = { value, value };
       ranges.push_back (r);
     }
   else
@@ -11086,7 +11101,7 @@ read_structure_type (struct die_info *die, struct dwarf2_cu *cu)
   if (attr != nullptr)
     {
       if (attr->form_is_constant ())
-	type->set_length (attr->constant_value (0));
+	type->set_length (attr->unsigned_constant ().value_or (0));
       else
 	{
 	  struct dynamic_prop prop;
@@ -11231,12 +11246,14 @@ handle_variant (struct die_info *die, struct type *type,
     {
       discr = dwarf2_attr (die, DW_AT_discr_list, cu);
       if (discr == nullptr || discr->as_block ()->size == 0)
-	variant.default_branch = true;
+	{
+	  /* Nothing to do here -- default branch.  */
+	}
       else
 	variant.discr_list_data = discr->as_block ();
     }
   else
-    variant.discriminant_value = discr->constant_value (0);
+    variant.discriminant_attr = discr;
 
   for (die_info *variant_child : die->children ())
     handle_struct_member_die (variant_child, type, fi, template_args, cu);
@@ -11562,25 +11579,30 @@ die_byte_order (die_info *die, dwarf2_cu *cu, enum bfd_endian *byte_order)
 
 /* Assuming DIE is an enumeration type, and TYPE is its associated
    type, update TYPE using some information only available in DIE's
-   children.  In particular, the fields are computed.  */
+   children.  In particular, the fields are computed.  If IS_UNSIGNED
+   is set, the enumeration type's sign is already known (a true value
+   means unsigned), and so examining the constants to determine the
+   sign isn't needed; when this is unset, the enumerator constants are
+   read as signed values.  */
 
 static void
 update_enumeration_type_from_children (struct die_info *die,
 				       struct type *type,
-				       struct dwarf2_cu *cu)
+				       struct dwarf2_cu *cu,
+				       std::optional<bool> is_unsigned)
 {
-  int unsigned_enum = 1;
-  int flag_enum = 1;
+  /* This is used to check whether the enum is signed or unsigned; for
+     simplicity, it is always correct regardless of whether
+     IS_UNSIGNED is set.  */
+  bool unsigned_enum = is_unsigned.value_or (true);
+  bool flag_enum = true;
 
-  auto_obstack obstack;
   std::vector<struct field> fields;
 
   for (die_info *child_die : die->children ())
     {
       struct attribute *attr;
       LONGEST value;
-      const gdb_byte *bytes;
-      struct dwarf2_locexpr_baton *baton;
       const char *name;
 
       if (child_die->tag != DW_TAG_enumerator)
@@ -11594,19 +11616,26 @@ update_enumeration_type_from_children (struct die_info *die,
       if (name == NULL)
 	name = "<anonymous enumerator>";
 
-      dwarf2_const_value_attr (attr, type, name, &obstack, cu,
-			       &value, &bytes, &baton);
-      if (value < 0)
-	{
-	  unsigned_enum = 0;
-	  flag_enum = 0;
-	}
+      /* Can't check UNSIGNED_ENUM here because that is
+	 optimistic.  */
+      if (is_unsigned.has_value () && *is_unsigned)
+	value = attr->unsigned_constant ().value_or (0);
       else
 	{
-	  if (count_one_bits_ll (value) >= 2)
-	    flag_enum = 0;
+	  /* Read as signed, either because we don't know the sign or
+	     because we know it is definitely signed.  */
+	  value = attr->signed_constant ().value_or (0);
+
+	  if (value < 0)
+	    {
+	      unsigned_enum = false;
+	      flag_enum = false;
+	    }
 	}
 
+      if (flag_enum && count_one_bits_ll (value) >= 2)
+	flag_enum = false;
+
       struct field &field = fields.emplace_back ();
       field.set_name (dwarf2_physname (name, child_die, cu));
       field.set_loc_enumval (value);
@@ -11615,13 +11644,10 @@ update_enumeration_type_from_children (struct die_info *die,
   if (!fields.empty ())
     type->copy_fields (fields);
   else
-    flag_enum = 0;
+    flag_enum = false;
 
-  if (unsigned_enum)
-    type->set_is_unsigned (true);
-
-  if (flag_enum)
-    type->set_is_flag_enum (true);
+  type->set_is_unsigned (unsigned_enum);
+  type->set_is_flag_enum (flag_enum);
 }
 
 /* Given a DW_AT_enumeration_type die, set its type.  We do not
@@ -11665,7 +11691,7 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
 
   attr = dwarf2_attr (die, DW_AT_byte_size, cu);
   if (attr != nullptr)
-    type->set_length (attr->constant_value (0));
+    type->set_length (attr->unsigned_constant ().value_or (0));
   else
     type->set_length (0);
 
@@ -11679,6 +11705,11 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
   if (die_is_declaration (die, cu))
     type->set_is_stub (true);
 
+  /* If the underlying type is known, and is unsigned, then we'll
+     assume the enumerator constants are unsigned.  Otherwise we have
+     to assume they are signed.  */
+  std::optional<bool> is_unsigned;
+
   /* If this type has an underlying type that is not a stub, then we
      may use its attributes.  We always use the "unsigned" attribute
      in this situation, because ordinarily we guess whether the type
@@ -11691,7 +11722,8 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
       struct type *underlying_type = type->target_type ();
       underlying_type = check_typedef (underlying_type);
 
-      type->set_is_unsigned (underlying_type->is_unsigned ());
+      is_unsigned = underlying_type->is_unsigned ();
+      type->set_is_unsigned (*is_unsigned);
 
       if (type->length () == 0)
 	type->set_length (underlying_type->length ());
@@ -11711,7 +11743,7 @@ read_enumeration_type (struct die_info *die, struct dwarf2_cu *cu)
      Note that, as usual, this must come after set_die_type to avoid
      infinite recursion when trying to compute the names of the
      enumerators.  */
-  update_enumeration_type_from_children (die, type, cu);
+  update_enumeration_type_from_children (die, type, cu, is_unsigned);
 
   return type;
 }
@@ -12061,7 +12093,7 @@ read_array_type (struct die_info *die, struct dwarf2_cu *cu)
 
   attr = dwarf2_attr (die, DW_AT_bit_stride, cu);
   if (attr != NULL)
-    bit_stride = attr->constant_value (0);
+    bit_stride = attr->unsigned_constant ().value_or (0);
 
   /* Irix 6.2 native cc creates array types without children for
      arrays with unspecified length.  */
@@ -12285,7 +12317,7 @@ mark_common_block_symbol_computed (struct symbol *sym,
 
   if (member_loc->form_is_constant ())
     {
-      offset = member_loc->constant_value (0);
+      offset = member_loc->unsigned_constant ().value_or (0);
       baton->size += 1 /* DW_OP_addr */ + cu->header.addr_size;
     }
   else
@@ -12600,7 +12632,8 @@ read_tag_pointer_type (struct die_info *die, struct dwarf2_cu *cu)
 
   attr_byte_size = dwarf2_attr (die, DW_AT_byte_size, cu);
   if (attr_byte_size)
-    byte_size = attr_byte_size->constant_value (cu_header->addr_size);
+    byte_size = (attr_byte_size->unsigned_constant ()
+		 .value_or (cu_header->addr_size));
   else
     byte_size = cu_header->addr_size;
 
@@ -12712,7 +12745,8 @@ read_tag_reference_type (struct die_info *die, struct dwarf2_cu *cu,
   type = lookup_reference_type (target_type, refcode);
   attr = dwarf2_attr (die, DW_AT_byte_size, cu);
   if (attr != nullptr)
-    type->set_length (attr->constant_value (cu_header->addr_size));
+    type->set_length (attr->unsigned_constant ()
+		      .value_or (cu_header->addr_size));
   else
     type->set_length (cu_header->addr_size);
 
@@ -12876,9 +12910,7 @@ read_tag_string_type (struct die_info *die, struct dwarf2_cu *cu)
 	len = dwarf2_attr (die, DW_AT_byte_size, cu);
       if (len != nullptr && len->form_is_constant ())
 	{
-	  /* Pass 0 as the default as we know this attribute is constant
-	     and the default value will not be returned.  */
-	  LONGEST sz = len->constant_value (0);
+	  LONGEST sz = len->unsigned_constant ().value_or (0);
 	  prop_type = objfile_int_type (objfile, sz, true);
 	}
       else
@@ -12897,15 +12929,14 @@ read_tag_string_type (struct die_info *die, struct dwarf2_cu *cu)
   else if (attr != nullptr)
     {
       /* This DW_AT_string_length just contains the length with no
-	 indirection.  There's no need to create a dynamic property in this
-	 case.  Pass 0 for the default value as we know it will not be
-	 returned in this case.  */
-      length = attr->constant_value (0);
+	 indirection.  There's no need to create a dynamic property in
+	 this case.  */
+      length = attr->unsigned_constant ().value_or (0);
     }
   else if ((attr = dwarf2_attr (die, DW_AT_byte_size, cu)) != nullptr)
     {
       /* We don't currently support non-constant byte sizes for strings.  */
-      length = attr->constant_value (1);
+      length = attr->unsigned_constant ().value_or (1);
     }
   else
     {
@@ -13214,10 +13245,10 @@ get_mpz (struct dwarf2_cu *cu, gdb_mpz *value, struct attribute *attr)
 		   ? BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE,
 		   true);
     }
-  else if (attr->form_is_unsigned ())
+  else if (attr->form_is_strictly_unsigned ())
     *value = gdb_mpz (attr->as_unsigned ());
   else
-    *value = gdb_mpz (attr->constant_value (1));
+    *value = gdb_mpz (attr->signed_constant ().value_or (1));
 }
 
 /* Assuming DIE is a rational DW_TAG_constant, read the DIE's
@@ -13396,14 +13427,14 @@ finish_fixed_point_type (struct type *type, const char *suffix,
     }
   else if (attr->name == DW_AT_binary_scale)
     {
-      LONGEST scale_exp = attr->constant_value (0);
+      LONGEST scale_exp = attr->signed_constant ().value_or (0);
       gdb_mpz &num_or_denom = scale_exp > 0 ? scale_num : scale_denom;
 
       num_or_denom <<= std::abs (scale_exp);
     }
   else if (attr->name == DW_AT_decimal_scale)
     {
-      LONGEST scale_exp = attr->constant_value (0);
+      LONGEST scale_exp = attr->signed_constant ().value_or (0);
       gdb_mpz &num_or_denom = scale_exp > 0 ? scale_num : scale_denom;
 
       num_or_denom = gdb_mpz::pow (10, std::abs (scale_exp));
@@ -13615,7 +13646,7 @@ read_base_type (struct die_info *die, struct dwarf2_cu *cu)
     }
   attr = dwarf2_attr (die, DW_AT_byte_size, cu);
   if (attr != nullptr)
-    bits = attr->constant_value (0) * TARGET_CHAR_BIT;
+    bits = attr->unsigned_constant ().value_or (0) * TARGET_CHAR_BIT;
   name = dwarf2_full_name (nullptr, die, cu);
   if (!name)
     complaint (_("DW_AT_name missing from DW_TAG_base_type"));
@@ -13766,22 +13797,28 @@ read_base_type (struct die_info *die, struct dwarf2_cu *cu)
       attr = dwarf2_attr (die, DW_AT_bit_size, cu);
       if (attr != nullptr && attr->form_is_constant ())
 	{
-	  unsigned real_bit_size = attr->constant_value (0);
+	  unsigned real_bit_size = attr->unsigned_constant ().value_or (0);
 	  if (real_bit_size >= 0 && real_bit_size <= 8 * type->length ())
 	    {
 	      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;
 		}
 	    }
 	}
@@ -14094,8 +14131,13 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
 
   LONGEST bias = 0;
   struct attribute *bias_attr = dwarf2_attr (die, DW_AT_GNU_bias, cu);
-  if (bias_attr != nullptr && bias_attr->form_is_constant ())
-    bias = bias_attr->constant_value (0);
+  if (bias_attr != nullptr)
+    {
+      if (base_type->is_unsigned ())
+	bias = (LONGEST) bias_attr->unsigned_constant ().value_or (0);
+      else
+	bias = bias_attr->signed_constant ().value_or (0);
+    }
 
   /* Normally, the DWARF producers are expected to use a signed
      constant form (Eg. DW_FORM_sdata) to express negative bounds.
@@ -14182,7 +14224,7 @@ read_subrange_type (struct die_info *die, struct dwarf2_cu *cu)
 
   attr = dwarf2_attr (die, DW_AT_byte_size, cu);
   if (attr != nullptr)
-    range_type->set_length (attr->constant_value (0));
+    range_type->set_length (attr->unsigned_constant ().value_or (0));
 
   maybe_set_alignment (cu, die, range_type);
 
@@ -14914,10 +14956,12 @@ cutu_reader::read_attribute_value (attribute *attr, unsigned form,
       info_ptr += 2;
       break;
     case DW_FORM_data4:
+    case DW_FORM_ref_sup4:
       attr->set_unsigned (read_4_bytes (m_abfd, info_ptr));
       info_ptr += 4;
       break;
     case DW_FORM_data8:
+    case DW_FORM_ref_sup8:
       attr->set_unsigned (read_8_bytes (m_abfd, info_ptr));
       info_ptr += 8;
       break;
@@ -14969,6 +15013,7 @@ cutu_reader::read_attribute_value (attribute *attr, unsigned form,
 	}
       [[fallthrough]];
     case DW_FORM_GNU_strp_alt:
+    case DW_FORM_strp_sup:
       {
 	dwz_file *dwz = per_objfile->per_bfd->get_dwz_file (true);
 	LONGEST str_offset
@@ -17166,13 +17211,10 @@ new_symbol (struct die_info *die, struct type *type, struct dwarf2_cu *cu,
    list was that this is unspecified.  We choose to always zero-extend
    because that is the interpretation long in use by GCC.  */
 
-static gdb_byte *
-dwarf2_const_value_data (const struct attribute *attr, struct obstack *obstack,
-			 struct dwarf2_cu *cu, LONGEST *value, int bits)
+static void
+dwarf2_const_value_data (const struct attribute *attr, LONGEST *value,
+			 int bits)
 {
-  struct objfile *objfile = cu->per_objfile->objfile;
-  enum bfd_endian byte_order = bfd_big_endian (objfile->obfd.get ()) ?
-				BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE;
   LONGEST l = attr->constant_value (0);
 
   if (bits < sizeof (*value) * 8)
@@ -17180,16 +17222,8 @@ dwarf2_const_value_data (const struct attribute *attr, struct obstack *obstack,
       l &= ((LONGEST) 1 << bits) - 1;
       *value = l;
     }
-  else if (bits == sizeof (*value) * 8)
-    *value = l;
   else
-    {
-      gdb_byte *bytes = (gdb_byte *) obstack_alloc (obstack, bits / 8);
-      store_unsigned_integer (bytes, bits / 8, byte_order, l);
-      return bytes;
-    }
-
-  return NULL;
+    *value = l;
 }
 
 /* Read a constant value from an attribute.  Either set *VALUE, or if
@@ -17251,6 +17285,7 @@ dwarf2_const_value_attr (const struct attribute *attr, struct type *type,
     case DW_FORM_strx:
     case DW_FORM_GNU_str_index:
     case DW_FORM_GNU_strp_alt:
+    case DW_FORM_strp_sup:
       /* The string is already allocated on the objfile obstack, point
 	 directly to it.  */
       *bytes = (const gdb_byte *) attr->as_string ();
@@ -17274,16 +17309,16 @@ dwarf2_const_value_attr (const struct attribute *attr, struct type *type,
 	 converted to host endianness, so we just need to sign- or
 	 zero-extend it as appropriate.  */
     case DW_FORM_data1:
-      *bytes = dwarf2_const_value_data (attr, obstack, cu, value, 8);
+      dwarf2_const_value_data (attr, value, 8);
       break;
     case DW_FORM_data2:
-      *bytes = dwarf2_const_value_data (attr, obstack, cu, value, 16);
+      dwarf2_const_value_data (attr, value, 16);
       break;
     case DW_FORM_data4:
-      *bytes = dwarf2_const_value_data (attr, obstack, cu, value, 32);
+      dwarf2_const_value_data (attr, value, 32);
       break;
     case DW_FORM_data8:
-      *bytes = dwarf2_const_value_data (attr, obstack, cu, value, 64);
+      dwarf2_const_value_data (attr, value, 64);
       break;
 
     case DW_FORM_sdata:
@@ -17457,7 +17492,7 @@ lookup_die_type (struct die_info *die, const struct attribute *attr,
 
   /* First see if we have it cached.  */
 
-  if (attr->form == DW_FORM_GNU_ref_alt)
+  if (attr->form_is_alt ())
     {
       sect_offset sect_off = attr->get_ref_die_offset ();
       dwarf2_per_cu *per_cu
@@ -18241,15 +18276,14 @@ follow_die_ref (struct die_info *src_die, const struct attribute *attr,
   struct dwarf2_cu *cu = *ref_cu;
   struct die_info *die;
 
-  if (attr->form != DW_FORM_GNU_ref_alt && src_die->sect_off == sect_off)
+  if (!attr->form_is_alt () && src_die->sect_off == sect_off)
     {
       /* Self-reference, we're done.  */
       return src_die;
     }
 
   die = follow_die_offset (sect_off,
-			   (attr->form == DW_FORM_GNU_ref_alt
-			    || cu->per_cu->is_dwz),
+			   attr->form_is_alt () || cu->per_cu->is_dwz,
 			   ref_cu);
   if (!die)
     error (_(DWARF_ERROR_PREFIX
@@ -18460,6 +18494,7 @@ dwarf2_fetch_constant_bytes (sect_offset sect_off,
     case DW_FORM_strx:
     case DW_FORM_GNU_str_index:
     case DW_FORM_GNU_strp_alt:
+    case DW_FORM_strp_sup:
       /* The string is already allocated on the objfile obstack, point
 	 directly to it.  */
       {
@@ -18488,31 +18523,23 @@ dwarf2_fetch_constant_bytes (sect_offset sect_off,
 	 zero-extend it as appropriate.  */
     case DW_FORM_data1:
       type = die_type (die, cu);
-      result = dwarf2_const_value_data (attr, obstack, cu, &value, 8);
-      if (result == NULL)
-	result = write_constant_as_bytes (obstack, byte_order,
-					  type, value, len);
+      dwarf2_const_value_data (attr, &value, 8);
+      result = write_constant_as_bytes (obstack, byte_order, type, value, len);
       break;
     case DW_FORM_data2:
       type = die_type (die, cu);
-      result = dwarf2_const_value_data (attr, obstack, cu, &value, 16);
-      if (result == NULL)
-	result = write_constant_as_bytes (obstack, byte_order,
-					  type, value, len);
+      dwarf2_const_value_data (attr, &value, 16);
+      result = write_constant_as_bytes (obstack, byte_order, type, value, len);
       break;
     case DW_FORM_data4:
       type = die_type (die, cu);
-      result = dwarf2_const_value_data (attr, obstack, cu, &value, 32);
-      if (result == NULL)
-	result = write_constant_as_bytes (obstack, byte_order,
-					  type, value, len);
+      dwarf2_const_value_data (attr, &value, 32);
+      result = write_constant_as_bytes (obstack, byte_order, type, value, len);
       break;
     case DW_FORM_data8:
       type = die_type (die, cu);
-      result = dwarf2_const_value_data (attr, obstack, cu, &value, 64);
-      if (result == NULL)
-	result = write_constant_as_bytes (obstack, byte_order,
-					  type, value, len);
+      dwarf2_const_value_data (attr, &value, 64);
+      result = write_constant_as_bytes (obstack, byte_order, type, value, len);
       break;
 
     case DW_FORM_sdata: