3 use rustc::hir::def_id::{DefId, DefIndex, DefIndexAddressSpace};
4 use rustc_serialize::opaque::Encoder;
9 /// While we are generating the metadata, we also track the position
10 /// of each DefIndex. It is not required that all definitions appear
11 /// in the metadata, nor that they are serialized in order, and
12 /// therefore we first allocate the vector here and fill it with
13 /// `u32::MAX`. Whenever an index is visited, we fill in the
14 /// appropriate spot by calling `record_position`. We should never
15 /// visit the same index twice.
17 positions: [Vec<u32>; 2]
21 pub fn new((max_index_lo, max_index_hi): (usize, usize)) -> Index {
23 positions: [vec![u32::MAX; max_index_lo],
24 vec![u32::MAX; max_index_hi]],
28 pub fn record(&mut self, def_id: DefId, entry: Lazy<Entry<'_>>) {
29 assert!(def_id.is_local());
30 self.record_index(def_id.index, entry);
33 pub fn record_index(&mut self, item: DefIndex, entry: Lazy<Entry<'_>>) {
34 assert!(entry.position < (u32::MAX as usize));
35 let position = entry.position as u32;
36 let space_index = item.address_space().index();
37 let array_index = item.as_array_index();
39 assert!(self.positions[space_index][array_index] == u32::MAX,
40 "recorded position for item {:?} twice, first at {:?} and now at {:?}",
42 self.positions[space_index][array_index],
45 self.positions[space_index][array_index] = position.to_le();
48 pub fn write_index(&self, buf: &mut Encoder) -> LazySeq<Index> {
49 let pos = buf.position();
51 // First we write the length of the lower range ...
52 buf.emit_raw_bytes(words_to_bytes(&[(self.positions[0].len() as u32).to_le()]));
53 // ... then the values in the lower range ...
54 buf.emit_raw_bytes(words_to_bytes(&self.positions[0][..]));
55 // ... then the values in the higher range.
56 buf.emit_raw_bytes(words_to_bytes(&self.positions[1][..]));
57 LazySeq::with_position_and_length(pos as usize,
58 self.positions[0].len() + self.positions[1].len() + 1)
62 impl<'tcx> LazySeq<Index> {
63 /// Given the metadata, extract out the offset of a particular
64 /// DefIndex (if any).
66 pub fn lookup(&self, bytes: &[u8], def_index: DefIndex) -> Option<Lazy<Entry<'tcx>>> {
67 let words = &bytes_to_words(&bytes[self.position..])[..self.len];
69 debug!("Index::lookup: index={:?} words.len={:?}",
73 let positions = match def_index.address_space() {
74 DefIndexAddressSpace::Low => &words[1..],
75 DefIndexAddressSpace::High => {
76 // This is a DefIndex in the higher range, so find out where
78 let lo_count = u32::from_le(words[0].get()) as usize;
79 &words[lo_count + 1 .. ]
83 let array_index = def_index.as_array_index();
84 let position = u32::from_le(positions[array_index].get());
85 if position == u32::MAX {
86 debug!("Index::lookup: position=u32::MAX");
89 debug!("Index::lookup: position={:?}", position);
90 Some(Lazy::with_position(position as usize))
97 struct Unaligned<T>(T);
99 // The derived Clone impl is unsafe for this packed struct since it needs to pass a reference to
100 // the field to `T::clone`, but this reference may not be properly aligned.
101 impl<T: Copy> Clone for Unaligned<T> {
102 fn clone(&self) -> Self {
107 impl<T> Unaligned<T> {
108 fn get(self) -> T { self.0 }
111 fn bytes_to_words(b: &[u8]) -> &[Unaligned<u32>] {
112 unsafe { slice::from_raw_parts(b.as_ptr() as *const Unaligned<u32>, b.len() / 4) }
115 fn words_to_bytes(w: &[u32]) -> &[u8] {
116 unsafe { slice::from_raw_parts(w.as_ptr() as *const u8, w.len() * 4) }