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Auto merge of #115418 - Zoxc:freeze-source, r=oli-obk

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Use `Freeze` for `SourceFile`

This uses the `Freeze` type in `SourceFile` to let accessing `external_src` and `lines` be lock-free.

Behavior of `add_external_src` is changed to set `ExternalSourceKind::AbsentErr` on a hash mismatch which matches the documentation. `ExternalSourceKind::Unneeded` was removed as it's unused.

Based on https://github.com/rust-lang/rust/pull/115401.
This commit is contained in:
bors 2023-09-08 17:20:23 +00:00
commit 26f4b72724
16 changed files with 294 additions and 225 deletions
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313
compiler/rustc_span/src/lib.rs
View file

@ -33,7 +33,7 @@ extern crate rustc_macros;
#[macro_use]
extern crate tracing;
use rustc_data_structures::AtomicRef;
use rustc_data_structures::{cold_path, AtomicRef};
use rustc_macros::HashStable_Generic;
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
@ -64,7 +64,7 @@ pub mod fatal_error;
pub mod profiling;
use rustc_data_structures::stable_hasher::{Hash128, Hash64, HashStable, StableHasher};
use rustc_data_structures::sync::{Lock, Lrc};
use rustc_data_structures::sync::{FreezeLock, FreezeWriteGuard, Lock, Lrc};
use std::borrow::Cow;
use std::cmp::{self, Ordering};
@ -1206,7 +1206,6 @@ pub enum ExternalSourceKind {
AbsentOk,
/// A failed attempt has been made to load the external source.
AbsentErr,
Unneeded,
}
impl ExternalSource {
@ -1343,13 +1342,13 @@ pub struct SourceFile {
pub src_hash: SourceFileHash,
/// The external source code (used for external crates, which will have a `None`
/// value as `self.src`.
pub external_src: Lock<ExternalSource>,
pub external_src: FreezeLock<ExternalSource>,
/// The start position of this source in the `SourceMap`.
pub start_pos: BytePos,
/// The byte length of this source.
pub source_len: RelativeBytePos,
/// Locations of lines beginnings in the source code.
pub lines: Lock<SourceFileLines>,
pub lines: FreezeLock<SourceFileLines>,
/// Locations of multi-byte characters in the source code.
pub multibyte_chars: Vec<MultiByteChar>,
/// Width of characters that are not narrow in the source code.
@ -1368,10 +1367,10 @@ impl Clone for SourceFile {
name: self.name.clone(),
src: self.src.clone(),
src_hash: self.src_hash,
external_src: Lock::new(self.external_src.borrow().clone()),
external_src: self.external_src.clone(),
start_pos: self.start_pos,
source_len: self.source_len,
lines: Lock::new(self.lines.borrow().clone()),
lines: self.lines.clone(),
multibyte_chars: self.multibyte_chars.clone(),
non_narrow_chars: self.non_narrow_chars.clone(),
normalized_pos: self.normalized_pos.clone(),
@ -1389,64 +1388,63 @@ impl<S: Encoder> Encodable<S> for SourceFile {
self.source_len.encode(s);
// We are always in `Lines` form by the time we reach here.
assert!(self.lines.borrow().is_lines());
self.lines(|lines| {
// Store the length.
s.emit_u32(lines.len() as u32);
assert!(self.lines.read().is_lines());
let lines = self.lines();
// Store the length.
s.emit_u32(lines.len() as u32);
// Compute and store the difference list.
if lines.len() != 0 {
let max_line_length = if lines.len() == 1 {
0
} else {
lines
.array_windows()
.map(|&[fst, snd]| snd - fst)
.map(|bp| bp.to_usize())
.max()
.unwrap()
};
// Compute and store the difference list.
if lines.len() != 0 {
let max_line_length = if lines.len() == 1 {
0
} else {
lines
.array_windows()
.map(|&[fst, snd]| snd - fst)
.map(|bp| bp.to_usize())
.max()
.unwrap()
};
let bytes_per_diff: usize = match max_line_length {
0..=0xFF => 1,
0x100..=0xFFFF => 2,
_ => 4,
};
let bytes_per_diff: usize = match max_line_length {
0..=0xFF => 1,
0x100..=0xFFFF => 2,
_ => 4,
};
// Encode the number of bytes used per diff.
s.emit_u8(bytes_per_diff as u8);
// Encode the number of bytes used per diff.
s.emit_u8(bytes_per_diff as u8);
// Encode the first element.
assert_eq!(lines[0], RelativeBytePos(0));
// Encode the first element.
assert_eq!(lines[0], RelativeBytePos(0));
// Encode the difference list.
let diff_iter = lines.array_windows().map(|&[fst, snd]| snd - fst);
let num_diffs = lines.len() - 1;
let mut raw_diffs;
match bytes_per_diff {
1 => {
raw_diffs = Vec::with_capacity(num_diffs);
for diff in diff_iter {
raw_diffs.push(diff.0 as u8);
}
// Encode the difference list.
let diff_iter = lines.array_windows().map(|&[fst, snd]| snd - fst);
let num_diffs = lines.len() - 1;
let mut raw_diffs;
match bytes_per_diff {
1 => {
raw_diffs = Vec::with_capacity(num_diffs);
for diff in diff_iter {
raw_diffs.push(diff.0 as u8);
}
2 => {
raw_diffs = Vec::with_capacity(bytes_per_diff * num_diffs);
for diff in diff_iter {
raw_diffs.extend_from_slice(&(diff.0 as u16).to_le_bytes());
}
}
4 => {
raw_diffs = Vec::with_capacity(bytes_per_diff * num_diffs);
for diff in diff_iter {
raw_diffs.extend_from_slice(&(diff.0).to_le_bytes());
}
}
_ => unreachable!(),
}
s.emit_raw_bytes(&raw_diffs);
2 => {
raw_diffs = Vec::with_capacity(bytes_per_diff * num_diffs);
for diff in diff_iter {
raw_diffs.extend_from_slice(&(diff.0 as u16).to_le_bytes());
}
}
4 => {
raw_diffs = Vec::with_capacity(bytes_per_diff * num_diffs);
for diff in diff_iter {
raw_diffs.extend_from_slice(&(diff.0).to_le_bytes());
}
}
_ => unreachable!(),
}
});
s.emit_raw_bytes(&raw_diffs);
}
self.multibyte_chars.encode(s);
self.non_narrow_chars.encode(s);
@ -1488,8 +1486,8 @@ impl<D: Decoder> Decodable<D> for SourceFile {
src_hash,
// Unused - the metadata decoder will construct
// a new SourceFile, filling in `external_src` properly
external_src: Lock::new(ExternalSource::Unneeded),
lines: Lock::new(lines),
external_src: FreezeLock::frozen(ExternalSource::Unneeded),
lines: FreezeLock::new(lines),
multibyte_chars,
non_narrow_chars,
normalized_pos,
@ -1530,10 +1528,10 @@ impl SourceFile {
name,
src: Some(Lrc::new(src)),
src_hash,
external_src: Lock::new(ExternalSource::Unneeded),
external_src: FreezeLock::frozen(ExternalSource::Unneeded),
start_pos: BytePos::from_u32(0),
source_len: RelativeBytePos::from_u32(source_len),
lines: Lock::new(SourceFileLines::Lines(lines)),
lines: FreezeLock::frozen(SourceFileLines::Lines(lines)),
multibyte_chars,
non_narrow_chars,
normalized_pos,
@ -1542,65 +1540,82 @@ impl SourceFile {
})
}
pub fn lines<F, R>(&self, f: F) -> R
where
F: FnOnce(&[RelativeBytePos]) -> R,
{
let mut guard = self.lines.borrow_mut();
match &*guard {
SourceFileLines::Lines(lines) => f(lines),
SourceFileLines::Diffs(SourceFileDiffs { bytes_per_diff, num_diffs, raw_diffs }) => {
// Convert from "diffs" form to "lines" form.
let num_lines = num_diffs + 1;
let mut lines = Vec::with_capacity(num_lines);
let mut line_start = RelativeBytePos(0);
lines.push(line_start);
/// This converts the `lines` field to contain `SourceFileLines::Lines` if needed and freezes it.
fn convert_diffs_to_lines_frozen(&self) {
let mut guard = if let Some(guard) = self.lines.try_write() { guard } else { return };
assert_eq!(*num_diffs, raw_diffs.len() / bytes_per_diff);
match bytes_per_diff {
1 => {
lines.extend(raw_diffs.into_iter().map(|&diff| {
line_start = line_start + RelativeBytePos(diff as u32);
line_start
}));
}
2 => {
lines.extend((0..*num_diffs).map(|i| {
let pos = bytes_per_diff * i;
let bytes = [raw_diffs[pos], raw_diffs[pos + 1]];
let diff = u16::from_le_bytes(bytes);
line_start = line_start + RelativeBytePos(diff as u32);
line_start
}));
}
4 => {
lines.extend((0..*num_diffs).map(|i| {
let pos = bytes_per_diff * i;
let bytes = [
raw_diffs[pos],
raw_diffs[pos + 1],
raw_diffs[pos + 2],
raw_diffs[pos + 3],
];
let diff = u32::from_le_bytes(bytes);
line_start = line_start + RelativeBytePos(diff);
line_start
}));
}
_ => unreachable!(),
}
let res = f(&lines);
*guard = SourceFileLines::Lines(lines);
res
let SourceFileDiffs { bytes_per_diff, num_diffs, raw_diffs } = match &*guard {
SourceFileLines::Diffs(diffs) => diffs,
SourceFileLines::Lines(..) => {
FreezeWriteGuard::freeze(guard);
return;
}
};
// Convert from "diffs" form to "lines" form.
let num_lines = num_diffs + 1;
let mut lines = Vec::with_capacity(num_lines);
let mut line_start = RelativeBytePos(0);
lines.push(line_start);
assert_eq!(*num_diffs, raw_diffs.len() / bytes_per_diff);
match bytes_per_diff {
1 => {
lines.extend(raw_diffs.into_iter().map(|&diff| {
line_start = line_start + RelativeBytePos(diff as u32);
line_start
}));
}
2 => {
lines.extend((0..*num_diffs).map(|i| {
let pos = bytes_per_diff * i;
let bytes = [raw_diffs[pos], raw_diffs[pos + 1]];
let diff = u16::from_le_bytes(bytes);
line_start = line_start + RelativeBytePos(diff as u32);
line_start
}));
}
4 => {
lines.extend((0..*num_diffs).map(|i| {
let pos = bytes_per_diff * i;
let bytes = [
raw_diffs[pos],
raw_diffs[pos + 1],
raw_diffs[pos + 2],
raw_diffs[pos + 3],
];
let diff = u32::from_le_bytes(bytes);
line_start = line_start + RelativeBytePos(diff);
line_start
}));
}
_ => unreachable!(),
}
*guard = SourceFileLines::Lines(lines);
FreezeWriteGuard::freeze(guard);
}
pub fn lines(&self) -> &[RelativeBytePos] {
if let Some(SourceFileLines::Lines(lines)) = self.lines.get() {
return &lines[..];
}
cold_path(|| {
self.convert_diffs_to_lines_frozen();
if let Some(SourceFileLines::Lines(lines)) = self.lines.get() {
return &lines[..];
}
unreachable!()
})
}
/// Returns the `BytePos` of the beginning of the current line.
pub fn line_begin_pos(&self, pos: BytePos) -> BytePos {
let pos = self.relative_position(pos);
let line_index = self.lookup_line(pos).unwrap();
let line_start_pos = self.lines(|lines| lines[line_index]);
let line_start_pos = self.lines()[line_index];
self.absolute_position(line_start_pos)
}
@ -1612,35 +1627,37 @@ impl SourceFile {
where
F: FnOnce() -> Option<String>,
{
if matches!(
*self.external_src.borrow(),
ExternalSource::Foreign { kind: ExternalSourceKind::AbsentOk, .. }
) {
if !self.external_src.is_frozen() {
let src = get_src();
let mut external_src = self.external_src.borrow_mut();
// Check that no-one else have provided the source while we were getting it
if let ExternalSource::Foreign {
kind: src_kind @ ExternalSourceKind::AbsentOk, ..
} = &mut *external_src
{
if let Some(mut src) = src {
// The src_hash needs to be computed on the pre-normalized src.
if self.src_hash.matches(&src) {
normalize_src(&mut src);
*src_kind = ExternalSourceKind::Present(Lrc::new(src));
return true;
}
let src = src.and_then(|mut src| {
// The src_hash needs to be computed on the pre-normalized src.
self.src_hash.matches(&src).then(|| {
normalize_src(&mut src);
src
})
});
self.external_src.try_write().map(|mut external_src| {
if let ExternalSource::Foreign {
kind: src_kind @ ExternalSourceKind::AbsentOk,
..
} = &mut *external_src
{
*src_kind = if let Some(src) = src {
ExternalSourceKind::Present(Lrc::new(src))
} else {
ExternalSourceKind::AbsentErr
};
} else {
*src_kind = ExternalSourceKind::AbsentErr;
panic!("unexpected state {:?}", *external_src)
}
false
} else {
self.src.is_some() || external_src.get_source().is_some()
}
} else {
self.src.is_some() || self.external_src.borrow().get_source().is_some()
// Freeze this so we don't try to load the source again.
FreezeWriteGuard::freeze(external_src)
});
}
self.src.is_some() || self.external_src.read().get_source().is_some()
}
/// Gets a line from the list of pre-computed line-beginnings.
@ -1658,7 +1675,7 @@ impl SourceFile {
}
let begin = {
let line = self.lines(|lines| lines.get(line_number).copied())?;
let line = self.lines().get(line_number).copied()?;
line.to_usize()
};
@ -1682,7 +1699,7 @@ impl SourceFile {
}
pub fn count_lines(&self) -> usize {
self.lines(|lines| lines.len())
self.lines().len()
}
#[inline]
@ -1705,7 +1722,7 @@ impl SourceFile {
/// number. If the source_file is empty or the position is located before the
/// first line, `None` is returned.
pub fn lookup_line(&self, pos: RelativeBytePos) -> Option<usize> {
self.lines(|lines| lines.partition_point(|x| x <= &pos).checked_sub(1))
self.lines().partition_point(|x| x <= &pos).checked_sub(1)
}
pub fn line_bounds(&self, line_index: usize) -> Range<BytePos> {
@ -1713,15 +1730,13 @@ impl SourceFile {
return self.start_pos..self.start_pos;
}
self.lines(|lines| {
assert!(line_index < lines.len());
if line_index == (lines.len() - 1) {
self.absolute_position(lines[line_index])..self.end_position()
} else {
self.absolute_position(lines[line_index])
..self.absolute_position(lines[line_index + 1])
}
})
let lines = self.lines();
assert!(line_index < lines.len());
if line_index == (lines.len() - 1) {
self.absolute_position(lines[line_index])..self.end_position()
} else {
self.absolute_position(lines[line_index])..self.absolute_position(lines[line_index + 1])
}
}
/// Returns whether or not the file contains the given `SourceMap` byte
@ -1807,7 +1822,7 @@ impl SourceFile {
match self.lookup_line(pos) {
Some(a) => {
let line = a + 1; // Line numbers start at 1
let linebpos = self.lines(|lines| lines[a]);
let linebpos = self.lines()[a];
let linechpos = self.bytepos_to_file_charpos(linebpos);
let col = chpos - linechpos;
debug!("byte pos {:?} is on the line at byte pos {:?}", pos, linebpos);
@ -1827,7 +1842,7 @@ impl SourceFile {
let (line, col_or_chpos) = self.lookup_file_pos(pos);
if line > 0 {
let col = col_or_chpos;
let linebpos = self.lines(|lines| lines[line - 1]);
let linebpos = self.lines()[line - 1];
let col_display = {
let start_width_idx = self
.non_narrow_chars

14
compiler/rustc_span/src/source_map.rs
View file

@ -328,7 +328,7 @@ impl SourceMap {
name_hash: Hash128,
source_len: u32,
cnum: CrateNum,
file_local_lines: Lock<SourceFileLines>,
file_local_lines: FreezeLock<SourceFileLines>,
multibyte_chars: Vec<MultiByteChar>,
non_narrow_chars: Vec<NonNarrowChar>,
normalized_pos: Vec<NormalizedPos>,
@ -340,7 +340,7 @@ impl SourceMap {
name: filename,
src: None,
src_hash,
external_src: Lock::new(ExternalSource::Foreign {
external_src: FreezeLock::new(ExternalSource::Foreign {
kind: ExternalSourceKind::AbsentOk,
metadata_index,
}),
@ -564,7 +564,7 @@ impl SourceMap {
end: (local_end.sf.name.clone(), local_end.sf.start_pos),
})))
} else {
self.ensure_source_file_source_present(local_begin.sf.clone());
self.ensure_source_file_source_present(&local_begin.sf);
let start_index = local_begin.pos.to_usize();
let end_index = local_end.pos.to_usize();
@ -581,7 +581,7 @@ impl SourceMap {
if let Some(ref src) = local_begin.sf.src {
extract_source(src, start_index, end_index)
} else if let Some(src) = local_begin.sf.external_src.borrow().get_source() {
} else if let Some(src) = local_begin.sf.external_src.read().get_source() {
extract_source(src, start_index, end_index)
} else {
Err(SpanSnippetError::SourceNotAvailable { filename: local_begin.sf.name.clone() })
@ -873,7 +873,7 @@ impl SourceMap {
let sp = sp.data();
let local_begin = self.lookup_byte_offset(sp.lo);
let start_index = local_begin.pos.to_usize();
let src = local_begin.sf.external_src.borrow();
let src = local_begin.sf.external_src.read();
let snippet = if let Some(ref src) = local_begin.sf.src {
Some(&src[start_index..])
@ -983,7 +983,7 @@ impl SourceMap {
return 1;
}
let src = local_begin.sf.external_src.borrow();
let src = local_begin.sf.external_src.read();
let snippet = if let Some(src) = &local_begin.sf.src {
src
@ -1030,7 +1030,7 @@ impl SourceMap {
self.files().iter().fold(0, |a, f| a + f.count_lines())
}
pub fn ensure_source_file_source_present(&self, source_file: Lrc<SourceFile>) -> bool {
pub fn ensure_source_file_source_present(&self, source_file: &SourceFile) -> bool {
source_file.add_external_src(|| {
let FileName::Real(ref name) = source_file.name else {
return None;

4
compiler/rustc_span/src/source_map/tests.rs
View file

@ -1,6 +1,6 @@
use super::*;
use rustc_data_structures::sync::Lrc;
use rustc_data_structures::sync::{FreezeLock, Lrc};
fn init_source_map() -> SourceMap {
let sm = SourceMap::new(FilePathMapping::empty());
@ -246,7 +246,7 @@ fn t10() {
name_hash,
source_len.to_u32(),
CrateNum::new(0),
lines,
FreezeLock::new(lines.read().clone()),
multibyte_chars,
non_narrow_chars,
normalized_pos,

4
compiler/rustc_span/src/tests.rs
View file

@ -7,9 +7,7 @@ fn test_lookup_line() {
SourceFile::new(FileName::Anon(Hash64::ZERO), source, SourceFileHashAlgorithm::Sha256)
.unwrap();
sf.start_pos = BytePos(3);
sf.lines(|lines| {
assert_eq!(lines, &[RelativeBytePos(0), RelativeBytePos(14), RelativeBytePos(25)])
});
assert_eq!(sf.lines(), &[RelativeBytePos(0), RelativeBytePos(14), RelativeBytePos(25)]);
assert_eq!(sf.lookup_line(RelativeBytePos(0)), Some(0));
assert_eq!(sf.lookup_line(RelativeBytePos(1)), Some(0));