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rustc_metadata: use 0 in index::Index to indicate missing entries.

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This commit is contained in:
Eduard-Mihai Burtescu 2019-04-11 19:56:59 +03:00
parent ea134563e7
commit 83b3c39218
1 changed files with 7 additions and 13 deletions
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20
src/librustc_metadata/index.rs
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@ -2,9 +2,9 @@
use rustc::hir::def_id::{DefId, DefIndex};
use rustc_serialize::opaque::Encoder;
use std::convert::TryInto;
use std::marker::PhantomData;
use std::num::NonZeroUsize;
use std::u32;
use log::debug;
/// Helper trait, for encoding to, and decoding from, a fixed number of bytes.
@ -73,7 +73,7 @@ fn write_to_bytes(self, b: &mut [u8]) {
/// 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
/// `0`. Whenever an index is visited, we fill in the
/// appropriate spot by calling `record_position`. We should never
/// visit the same index twice.
crate struct Index<'tcx> {
@ -84,7 +84,7 @@ fn write_to_bytes(self, b: &mut [u8]) {
impl Index<'tcx> {
crate fn new(max_index: usize) -> Self {
Index {
positions: vec![0xff; max_index * 4],
positions: vec![0; max_index * 4],
_marker: PhantomData,
}
}
@ -95,12 +95,11 @@ impl Index<'tcx> {
}
fn record_index(&mut self, item: DefIndex, entry: Lazy<Entry<'tcx>>) {
assert!(entry.position.get() < (u32::MAX as usize));
let position = entry.position.get() as u32;
let position: u32 = entry.position.get().try_into().unwrap();
let array_index = item.index();
let positions = &mut self.positions;
assert!(u32::read_from_bytes_at(positions, array_index) == u32::MAX,
assert!(u32::read_from_bytes_at(positions, array_index) == 0,
"recorded position for item {:?} twice, first at {:?} and now at {:?}",
item,
u32::read_from_bytes_at(positions, array_index),
@ -130,12 +129,7 @@ impl Lazy<[Index<'tcx>]> {
let bytes = &bytes[self.position.get()..][..self.meta * 4];
let position = u32::read_from_bytes_at(bytes, def_index.index());
if position == u32::MAX {
debug!("Index::lookup: position=u32::MAX");
None
} else {
debug!("Index::lookup: position={:?}", position);
Some(Lazy::from_position(NonZeroUsize::new(position as usize).unwrap()))
}
debug!("Index::lookup: position={:?}", position);
NonZeroUsize::new(position as usize).map(Lazy::from_position)
}
}