1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
13 use rustc::hir::def_id::{DefId, DefIndex, DefIndexAddressSpace};
14 use std::io::{Cursor, Write};
18 /// While we are generating the metadata, we also track the position
19 /// of each DefIndex. It is not required that all definitions appear
20 /// in the metadata, nor that they are serialized in order, and
21 /// therefore we first allocate the vector here and fill it with
22 /// `u32::MAX`. Whenever an index is visited, we fill in the
23 /// appropriate spot by calling `record_position`. We should never
24 /// visit the same index twice.
26 positions: [Vec<u32>; 2]
30 pub fn new((max_index_lo, max_index_hi): (usize, usize)) -> Index {
32 positions: [vec![u32::MAX; max_index_lo],
33 vec![u32::MAX; max_index_hi]],
37 pub fn record(&mut self, def_id: DefId, entry: Lazy<Entry>) {
38 assert!(def_id.is_local());
39 self.record_index(def_id.index, entry);
42 pub fn record_index(&mut self, item: DefIndex, entry: Lazy<Entry>) {
43 assert!(entry.position < (u32::MAX as usize));
44 let position = entry.position as u32;
45 let space_index = item.address_space().index();
46 let array_index = item.as_array_index();
48 assert!(self.positions[space_index][array_index] == u32::MAX,
49 "recorded position for item {:?} twice, first at {:?} and now at {:?}",
51 self.positions[space_index][array_index],
54 self.positions[space_index][array_index] = position.to_le();
57 pub fn write_index(&self, buf: &mut Cursor<Vec<u8>>) -> LazySeq<Index> {
58 let pos = buf.position();
60 // First we write the length of the lower range ...
61 buf.write_all(words_to_bytes(&[(self.positions[0].len() as u32).to_le()])).unwrap();
62 // ... then the values in the lower range ...
63 buf.write_all(words_to_bytes(&self.positions[0][..])).unwrap();
64 // ... then the values in the higher range.
65 buf.write_all(words_to_bytes(&self.positions[1][..])).unwrap();
66 LazySeq::with_position_and_length(pos as usize,
67 self.positions[0].len() + self.positions[1].len() + 1)
71 impl<'tcx> LazySeq<Index> {
72 /// Given the metadata, extract out the offset of a particular
73 /// DefIndex (if any).
75 pub fn lookup(&self, bytes: &[u8], def_index: DefIndex) -> Option<Lazy<Entry<'tcx>>> {
76 let words = &bytes_to_words(&bytes[self.position..])[..self.len];
78 debug!("Index::lookup: index={:?} words.len={:?}",
82 let positions = match def_index.address_space() {
83 DefIndexAddressSpace::Low => &words[1..],
84 DefIndexAddressSpace::High => {
85 // This is a DefIndex in the higher range, so find out where
87 let lo_count = u32::from_le(words[0].get()) as usize;
88 &words[lo_count + 1 .. ]
92 let array_index = def_index.as_array_index();
93 let position = u32::from_le(positions[array_index].get());
94 if position == u32::MAX {
95 debug!("Index::lookup: position=u32::MAX");
98 debug!("Index::lookup: position={:?}", position);
99 Some(Lazy::with_position(position as usize))
106 struct Unaligned<T>(T);
108 // The derived Clone impl is unsafe for this packed struct since it needs to pass a reference to
109 // the field to `T::clone`, but this reference may not be properly aligned.
110 impl<T: Copy> Clone for Unaligned<T> {
111 fn clone(&self) -> Self {
116 impl<T> Unaligned<T> {
117 fn get(self) -> T { self.0 }
120 fn bytes_to_words(b: &[u8]) -> &[Unaligned<u32>] {
121 unsafe { slice::from_raw_parts(b.as_ptr() as *const Unaligned<u32>, b.len() / 4) }
124 fn words_to_bytes(w: &[u32]) -> &[u8] {
125 unsafe { slice::from_raw_parts(w.as_ptr() as *const u8, w.len() * 4) }