redo big_endian bitfield packing in a simpler and more correct way

diff --git a/type.c b/type.c
index 8211f63..7a406bd 100644 (file)
--- a/type.c
+++ b/type.c
@@ -1686,57 +1686,6 @@ type_t *make_array_type(type_t *element_type, size_t size,
        return identify_new_type(type);
 }
 
-static entity_t *pack_bitfield_members_big_endian(il_size_t *struct_offset,
-               il_alignment_t *struct_alignment, bool packed, entity_t *first)
-{
-       type_t        *current_base_type = NULL;
-       il_size_t      offset            = *struct_offset;
-       il_alignment_t alignment         = *struct_alignment;
-       size_t         bit_offset        = 0;
-
-       if (packed)
-               panic("packed bitfields on big-endian arch not supported yet");
-
-       entity_t *member;
-       for (member = first; member != NULL; member = member->base.next) {
-               if (member->kind != ENTITY_COMPOUND_MEMBER)
-                       continue;
-
-               type_t *type = member->declaration.type;
-               if (type->kind != TYPE_BITFIELD)
-                       break;
-
-               size_t  bit_size  = type->bitfield.bit_size;
-               type_t *base_type = skip_typeref(type->bitfield.base_type);
-
-               /* see if we need to start a new "bucket" */
-               if (base_type != current_base_type || bit_size > bit_offset) {
-                       if (current_base_type != NULL)
-                               offset += get_type_size(current_base_type);
-
-                       current_base_type = base_type;
-                       il_alignment_t base_alignment = get_type_alignment(base_type);
-                       il_alignment_t alignment_mask = base_alignment-1;
-                       if (base_alignment > alignment)
-                               alignment = base_alignment;
-                       offset     = (offset + base_alignment-1) & ~alignment_mask;
-                       bit_offset = get_type_size(base_type) * BITS_PER_BYTE;
-                       assert(bit_offset >= bit_size);
-               }
-
-               bit_offset -= bit_size;
-               member->compound_member.offset     = offset;
-               member->compound_member.bit_offset = bit_offset;
-       }
-
-       if (current_base_type != NULL)
-               offset += get_type_size(current_base_type);
-
-       *struct_offset    = offset;
-       *struct_alignment = alignment;
-       return member;
-}
-
 static entity_t *pack_bitfield_members(il_size_t *struct_offset,
                                        il_alignment_t *struct_alignment,
                                                                           bool packed, entity_t *first)
@@ -1773,8 +1722,14 @@ static entity_t *pack_bitfield_members(il_size_t *struct_offset,
                        }
                }
 
-               member->compound_member.offset     = offset;
-               member->compound_member.bit_offset = bit_offset;
+               if (byte_order_big_endian) {
+                       size_t base_size = get_type_size(base_type) * BITS_PER_BYTE;
+                       member->compound_member.offset     = offset & ~alignment_mask;
+                       member->compound_member.bit_offset = base_size - bit_offset - bit_size;
+               } else {
+                       member->compound_member.offset     = offset;
+                       member->compound_member.bit_offset = bit_offset;
+               }
 
                bit_offset += bit_size;
                offset     += bit_offset / BITS_PER_BYTE;
@@ -1818,14 +1773,8 @@ void layout_struct_type(compound_type_t *type)
                }
 
                if (skipped->kind == TYPE_BITFIELD) {
-                       if (byte_order_big_endian) {
-                               entry = pack_bitfield_members_big_endian(&offset, &alignment,
-                                                                        compound->packed,
-                                                                        entry);
-                       } else {
-                               entry = pack_bitfield_members(&offset, &alignment,
-                                                             compound->packed, entry);
-                       }
+                       entry = pack_bitfield_members(&offset, &alignment,
+                                                     compound->packed, entry);
                        continue;
                }