re PR middle-end/20371 (Some corner cases of MS bitfields don't work)

	PR middle-end/20371:
	* tree.h (record_layout_info_s): New member prev_packed.
	* stor-layout.c (update_alignment_for_field): Fix comment about
	KNOWN_ALIGN.  For MS bitfields, if we start a new run, make sure
	we start it properly aligned.
	(place_field): At the beginning of a record, pass 0 as KNOWN_ALIGN
	to update_alignment_for_field, and recompute it afterwards using
	the alignment of the record.
	When a packed bitfield precedes an MS bitfield, don't add padding
	at the end of the packed bitfield on behalf of the base type of
	the packed bit field.
	Don't adjust rli->bitpos at the end
	of an MS bitfield run if we already adjusted bitpos/offset for an
	alignment as large or larger than the bitfield type size.
	Take possible record alignment > BIGGEST_ALIGNMENT into account
	when calculating actual_align.
	Only put packed buit fields into rli->prev_field if they end up
	suitably aligned.
	Also set rli->remaining_in_alignment when we re-set rli->prev_field.
	Update rli->remaining_in_alignment when we have already started a
	run of bit fields and we process a packed bit field.

From-SVN: r99574

1 files changed, 3 insertions, 0 deletions

diff --git a/gcc/tree.h b/gcc/tree.h
index 4600d51..44a07af 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -3142,6 +3142,9 @@ typedef struct record_layout_info_s
   tree pending_statics;
   /* Bits remaining in the current alignment group */
   int remaining_in_alignment;
+  /* True if prev_field was packed and we haven't found any non-packed
+     fields that we have put in the same alignment group.  */
+  int prev_packed;
   /* True if we've seen a packed field that didn't have normal
      alignment anyway.  */
   int packed_maybe_necessary;