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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use schema::*;
use rustc::hir::def_id::{DefId, DefIndex, DefIndexAddressSpace};
use rustc_serialize::opaque::Encoder;
use std::slice;
use std::u32;
/// While we are generating the metadata, we also track the position
/// of each DefIndex. It is not required that all definitions appear
/// in the metadata, nor that they are serialized in order, and
/// therefore we first allocate the vector here and fill it with
/// `u32::MAX`. Whenever an index is visited, we fill in the
/// appropriate spot by calling `record_position`. We should never
/// visit the same index twice.
pub struct Index {
positions: [Vec<u32>; 2]
}
impl Index {
pub fn new((max_index_lo, max_index_hi): (usize, usize)) -> Index {
Index {
positions: [vec![u32::MAX; max_index_lo],
vec![u32::MAX; max_index_hi]],
}
}
pub fn record(&mut self, def_id: DefId, entry: Lazy<Entry>) {
assert!(def_id.is_local());
self.record_index(def_id.index, entry);
}
pub fn record_index(&mut self, item: DefIndex, entry: Lazy<Entry>) {
assert!(entry.position < (u32::MAX as usize));
let position = entry.position as u32;
let space_index = item.address_space().index();
let array_index = item.as_array_index();
assert!(self.positions[space_index][array_index] == u32::MAX,
"recorded position for item {:?} twice, first at {:?} and now at {:?}",
item,
self.positions[space_index][array_index],
position);
self.positions[space_index][array_index] = position.to_le();
}
pub fn write_index(&self, buf: &mut Encoder) -> LazySeq<Index> {
let pos = buf.position();
// First we write the length of the lower range ...
buf.emit_raw_bytes(words_to_bytes(&[(self.positions[0].len() as u32).to_le()]));
// ... then the values in the lower range ...
buf.emit_raw_bytes(words_to_bytes(&self.positions[0][..]));
// ... then the values in the higher range.
buf.emit_raw_bytes(words_to_bytes(&self.positions[1][..]));
LazySeq::with_position_and_length(pos as usize,
self.positions[0].len() + self.positions[1].len() + 1)
}
}
impl<'tcx> LazySeq<Index> {
/// Given the metadata, extract out the offset of a particular
/// DefIndex (if any).
#[inline(never)]
pub fn lookup(&self, bytes: &[u8], def_index: DefIndex) -> Option<Lazy<Entry<'tcx>>> {
let words = &bytes_to_words(&bytes[self.position..])[..self.len];
debug!("Index::lookup: index={:?} words.len={:?}",
def_index,
words.len());
let positions = match def_index.address_space() {
DefIndexAddressSpace::Low => &words[1..],
DefIndexAddressSpace::High => {
// This is a DefIndex in the higher range, so find out where
// that starts:
let lo_count = u32::from_le(words[0].get()) as usize;
&words[lo_count + 1 .. ]
}
};
let array_index = def_index.as_array_index();
let position = u32::from_le(positions[array_index].get());
if position == u32::MAX {
debug!("Index::lookup: position=u32::MAX");
None
} else {
debug!("Index::lookup: position={:?}", position);
Some(Lazy::with_position(position as usize))
}
}
}
#[repr(packed)]
#[derive(Copy)]
struct Unaligned<T>(T);
// The derived Clone impl is unsafe for this packed struct since it needs to pass a reference to
// the field to `T::clone`, but this reference may not be properly aligned.
impl<T: Copy> Clone for Unaligned<T> {
fn clone(&self) -> Self {
*self
}
}
impl<T> Unaligned<T> {
fn get(self) -> T { self.0 }
}
fn bytes_to_words(b: &[u8]) -> &[Unaligned<u32>] {
unsafe { slice::from_raw_parts(b.as_ptr() as *const Unaligned<u32>, b.len() / 4) }
}
fn words_to_bytes(w: &[u32]) -> &[u8] {
unsafe { slice::from_raw_parts(w.as_ptr() as *const u8, w.len() * 4) }
}
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