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[PATCH] Fix wrong offset in DWARF


when a field has a non-constant size (this of course can happen in Ada :-),
simple_type_size_in_bits returns the alignment in bits but field_byte_offset 
picks BITS_PER_WORD for the field size; so a field with non-constant size at 
offset 0 with 16-bit alignment is wrongly output at offset 2.

Fixed by using simple_type_size_in_bits for the field size in this case.

Tested (GCC, GDB) on i586-suse-linux, OK for mainline?

2009-04-17  Eric Botcazou  <>

	* dwarf2out.c (field_byte_offset): Use the type size as the field size
	if the latter is not constant.

Eric Botcazou
Index: dwarf2out.c
--- dwarf2out.c	(revision 146259)
+++ dwarf2out.c	(working copy)
@@ -10900,21 +10900,22 @@ field_byte_offset (const_tree decl)
       unsigned HOST_WIDE_INT type_size_in_bits;
       type = field_type (decl);
+      type_size_in_bits = simple_type_size_in_bits (type);
+      type_align_in_bits = simple_type_align_in_bits (type);
       field_size_tree = DECL_SIZE (decl);
       /* The size could be unspecified if there was an error, or for
          a flexible array member.  */
-      if (! field_size_tree)
+      if (!field_size_tree)
         field_size_tree = bitsize_zero_node;
-      /* If we don't know the size of the field, pretend it's a full word.  */
+      /* If the size of the field is not constant, use the type size.  */
       if (host_integerp (field_size_tree, 1))
         field_size_in_bits = tree_low_cst (field_size_tree, 1);
-        field_size_in_bits = BITS_PER_WORD;
+        field_size_in_bits = type_size_in_bits;
-      type_size_in_bits = simple_type_size_in_bits (type);
-      type_align_in_bits = simple_type_align_in_bits (type);
       decl_align_in_bits = simple_decl_align_in_bits (decl);
       /* The GCC front-end doesn't make any attempt to keep track of the

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