void layout_union_type(compound_type_t *type)
{
assert(type->compound != NULL);
compound_t *compound = type->compound;
if (! compound->complete)
return;
il_size_t size = 0;
il_alignment_t alignment = compound->alignment;
entity_t *entry = compound->members.entities;
for (; entry != NULL; entry = entry->base.next) {
if (entry->kind != ENTITY_COMPOUND_MEMBER)
continue;
type_t *m_type = skip_typeref(entry->declaration.type);
if (! is_type_valid(skip_typeref(m_type)))
continue;
entry->compound_member.offset = 0;
il_size_t m_size = get_type_size(m_type);
if (m_size > size)
size = m_size;
il_alignment_t m_alignment = get_type_alignment_compound(m_type);
if (m_alignment > alignment)
alignment = m_alignment;
}
size = (size + alignment - 1) & -alignment;
compound->size = size;
compound->alignment = alignment;
}
static entity_t *pack_bitfield_members(il_size_t *struct_offset,
il_alignment_t *struct_alignment,
bool packed, entity_t *first)
{
il_size_t offset = *struct_offset;
il_alignment_t alignment = *struct_alignment;
size_t bit_offset = 0;
entity_t *member;
for (member = first; member != NULL; member = member->base.next) {
if (member->kind != ENTITY_COMPOUND_MEMBER)
continue;
if (!member->compound_member.bitfield)
break;
type_t *const base_type = skip_typeref(member->declaration.type);
il_alignment_t base_alignment = get_type_alignment_compound(base_type);
il_alignment_t alignment_mask = base_alignment-1;
if (base_alignment > alignment)
alignment = base_alignment;
size_t bit_size = member->compound_member.bit_size;
if (!packed) {
bit_offset += (offset & alignment_mask) * BITS_PER_BYTE;
offset &= ~alignment_mask;
size_t base_size = get_type_size(base_type) * BITS_PER_BYTE;
if (bit_offset + bit_size > base_size || bit_size == 0) {
offset += (bit_offset+BITS_PER_BYTE-1) / BITS_PER_BYTE;
offset = (offset + base_alignment-1) & ~alignment_mask;
bit_offset = 0;
}
}
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;
bit_offset %= BITS_PER_BYTE;
}
if (bit_offset > 0)
offset += 1;
*struct_offset = offset;
*struct_alignment = alignment;
return member;
}
unsigned get_type_alignment_compound(type_t const *const type)
{
switch (type->kind) {
case TYPE_ATOMIC:
case TYPE_COMPLEX:
case TYPE_IMAGINARY:
case TYPE_ENUM:
return atomic_type_properties[type->atomic.akind].struct_alignment;
case TYPE_TYPEDEF: {
il_alignment_t const alignment = get_type_alignment_compound(type->typedeft.typedefe->type);
return MAX(type->typedeft.typedefe->alignment, alignment);
}
case TYPE_TYPEOF:
return get_type_alignment_compound(type->typeoft.typeof_type);
default:
return get_type_alignment(type);
}
}
void layout_struct_type(compound_type_t *type)
{
assert(type->compound != NULL);
compound_t *compound = type->compound;
if (!compound->complete)
return;
if (type->compound->layouted)
return;
il_size_t offset = 0;
il_alignment_t alignment = compound->alignment;
bool need_pad = false;
entity_t *entry = compound->members.entities;
while (entry != NULL) {
if (entry->kind != ENTITY_COMPOUND_MEMBER) {
entry = entry->base.next;
continue;
}
type_t *const m_type = skip_typeref(entry->declaration.type);
if (!is_type_valid(m_type)) {
entry = entry->base.next;
continue;
}
if (entry->compound_member.bitfield) {
entry = pack_bitfield_members(&offset, &alignment,
compound->packed, entry);
continue;
}
il_alignment_t m_alignment = get_type_alignment_compound(m_type);
if (m_alignment > alignment)
alignment = m_alignment;
if (!compound->packed) {
il_size_t new_offset = (offset + m_alignment-1) & -m_alignment;
if (new_offset > offset) {
need_pad = true;
offset = new_offset;
}
}
entry->compound_member.offset = offset;
offset += get_type_size(m_type);
entry = entry->base.next;
}
if (!compound->packed) {
il_size_t new_offset = (offset + alignment-1) & -alignment;
if (new_offset > offset) {
need_pad = true;
offset = new_offset;
}
}
source_position_t const *const pos = &compound->base.source_position;
if (need_pad) {
warningf(WARN_PADDED, pos, "'%T' needs padding", type);
} else if (compound->packed) {
warningf(WARN_PACKED, pos, "superfluous packed attribute on '%T'", type);
}
compound->size = offset;
compound->alignment = alignment;
compound->layouted = true;
}
