+/* Classify field I of TYPE starting at BITOFFSET according to the rules for
+ structures and union types, and store the result in THECLASS. */
+
+static void
+amd64_classify_aggregate_field (struct type *type, int i,
+ enum amd64_reg_class theclass[2],
+ unsigned int bitoffset)
+{
+ struct type *subtype = check_typedef (type->field (i).type ());
+ enum amd64_reg_class subclass[2];
+ int bitsize = TYPE_FIELD_BITSIZE (type, i);
+
+ if (bitsize == 0)
+ bitsize = TYPE_LENGTH (subtype) * 8;
+
+ /* Ignore static fields, or empty fields, for example nested
+ empty structures.*/
+ if (field_is_static (&type->field (i)) || bitsize == 0)
+ return;
+
+ int bitpos = bitoffset + type->field (i).loc_bitpos ();
+ int pos = bitpos / 64;
+ int endpos = (bitpos + bitsize - 1) / 64;
+
+ if (subtype->code () == TYPE_CODE_STRUCT
+ || subtype->code () == TYPE_CODE_UNION)
+ {
+ /* Each field of an object is classified recursively. */
+ int j;
+ for (j = 0; j < subtype->num_fields (); j++)
+ amd64_classify_aggregate_field (subtype, j, theclass, bitpos);
+ return;
+ }
+
+ gdb_assert (pos == 0 || pos == 1);
+
+ amd64_classify (subtype, subclass);
+ theclass[pos] = amd64_merge_classes (theclass[pos], subclass[0]);
+ if (bitsize <= 64 && pos == 0 && endpos == 1)
+ /* This is a bit of an odd case: We have a field that would
+ normally fit in one of the two eightbytes, except that
+ it is placed in a way that this field straddles them.
+ This has been seen with a structure containing an array.
+
+ The ABI is a bit unclear in this case, but we assume that
+ this field's class (stored in subclass[0]) must also be merged
+ into class[1]. In other words, our field has a piece stored
+ in the second eight-byte, and thus its class applies to
+ the second eight-byte as well.
+
+ In the case where the field length exceeds 8 bytes,
+ it should not be necessary to merge the field class
+ into class[1]. As LEN > 8, subclass[1] is necessarily
+ different from AMD64_NO_CLASS. If subclass[1] is equal
+ to subclass[0], then the normal class[1]/subclass[1]
+ merging will take care of everything. For subclass[1]
+ to be different from subclass[0], I can only see the case
+ where we have a SSE/SSEUP or X87/X87UP pair, which both
+ use up all 16 bytes of the aggregate, and are already
+ handled just fine (because each portion sits on its own
+ 8-byte). */
+ theclass[1] = amd64_merge_classes (theclass[1], subclass[0]);
+ if (pos == 0)
+ theclass[1] = amd64_merge_classes (theclass[1], subclass[1]);
+}
+