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Commit 62b72bd

Browse files
Rollup merge of #147189 - yotamofek:pr/rustdoc/highlight-optimizations-2, r=GuillaumeGomez
Replace `rustc_span::Span` with a stripped down version for librustdoc's highlighter While profiling rustdoc's syntax highlighter, I noticed a lot of time being spent in the `Span` interner, due to the highlighter creating a lot of (new) spans. Since the only data from the `Span` that we use is the `hi` and `lo` byte positions - I replaced the regular `Span` with a simple one with two fields, and in my benchmarks it seemed to make a big dent in the highlighter's perf, so thought I would see what the perf runner says.
2 parents ca8ed7e + 2d03ab1 commit 62b72bd

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7 files changed

+80
-19
lines changed

7 files changed

+80
-19
lines changed

‎src/bootstrap/src/core/builder/mod.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1145,7 +1145,7 @@ impl<'a> Builder<'a> {
11451145
test::RunMakeCargo,
11461146
),
11471147
Kind::Miri => describe!(test::Crate),
1148-
Kind::Bench => describe!(test::Crate, test::CrateLibrustc),
1148+
Kind::Bench => describe!(test::Crate, test::CrateLibrustc, test::CrateRustdoc),
11491149
Kind::Doc => describe!(
11501150
doc::UnstableBook,
11511151
doc::UnstableBookGen,

‎src/librustdoc/html/highlight.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,15 +12,16 @@ use std::iter;
1212

1313
use rustc_data_structures::fx::FxIndexMap;
1414
use rustc_lexer::{Cursor, FrontmatterAllowed, LiteralKind, TokenKind};
15+
use rustc_span::BytePos;
1516
use rustc_span::edition::Edition;
1617
use rustc_span::symbol::Symbol;
17-
use rustc_span::{BytePos, DUMMY_SP, Span};
1818

1919
use super::format;
2020
use crate::clean::PrimitiveType;
2121
use crate::display::Joined as _;
2222
use crate::html::escape::EscapeBodyText;
2323
use crate::html::macro_expansion::ExpandedCode;
24+
use crate::html::render::span_map::{DUMMY_SP, Span};
2425
use crate::html::render::{Context, LinkFromSrc};
2526

2627
/// This type is needed in case we want to render links on items to allow to go to their definition.

‎src/librustdoc/html/highlight/tests.rs‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
11
use expect_test::expect_file;
22
use rustc_data_structures::fx::FxIndexMap;
33
use rustc_span::create_default_session_globals_then;
4+
use test::Bencher;
45

56
use super::{DecorationInfo, write_code};
67

@@ -81,3 +82,16 @@ let a = 4;";
8182
expect_file!["fixtures/decorations.html"].assert_eq(&html);
8283
});
8384
}
85+
86+
#[bench]
87+
fn bench_html_highlighting(b: &mut Bencher) {
88+
let src = include_str!("../../../../compiler/rustc_ast/src/visit.rs");
89+
90+
create_default_session_globals_then(|| {
91+
b.iter(|| {
92+
let mut out = String::new();
93+
write_code(&mut out, src, None, None, None);
94+
out
95+
});
96+
});
97+
}

‎src/librustdoc/html/render/context.rs‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@ use crate::formats::item_type::ItemType;
3030
use crate::html::escape::Escape;
3131
use crate::html::macro_expansion::ExpandedCode;
3232
use crate::html::markdown::{self, ErrorCodes, IdMap, plain_text_summary};
33+
use crate::html::render::span_map::Span;
3334
use crate::html::render::write_shared::write_shared;
3435
use crate::html::url_parts_builder::UrlPartsBuilder;
3536
use crate::html::{layout, sources, static_files};
@@ -139,7 +140,7 @@ pub(crate) struct SharedContext<'tcx> {
139140

140141
/// Correspondence map used to link types used in the source code pages to allow to click on
141142
/// links to jump to the type's definition.
142-
pub(crate) span_correspondence_map: FxHashMap<rustc_span::Span, LinkFromSrc>,
143+
pub(crate) span_correspondence_map: FxHashMap<Span, LinkFromSrc>,
143144
pub(crate) expanded_codes: FxHashMap<BytePos, Vec<ExpandedCode>>,
144145
/// The [`Cache`] used during rendering.
145146
pub(crate) cache: Cache,

‎src/librustdoc/html/render/mod.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -36,7 +36,7 @@ mod ordered_json;
3636
mod print_item;
3737
pub(crate) mod sidebar;
3838
mod sorted_template;
39-
mod span_map;
39+
pub(crate)mod span_map;
4040
mod type_layout;
4141
mod write_shared;
4242

‎src/librustdoc/html/render/span_map.rs‎

Lines changed: 54 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -8,11 +8,48 @@ use rustc_hir::{ExprKind, HirId, Item, ItemKind, Mod, Node, QPath};
88
use rustc_middle::hir::nested_filter;
99
use rustc_middle::ty::TyCtxt;
1010
use rustc_span::hygiene::MacroKind;
11-
use rustc_span::{BytePos, ExpnKind,Span};
11+
use rustc_span::{BytePos, ExpnKind};
1212

1313
use crate::clean::{self, PrimitiveType, rustc_span};
1414
use crate::html::sources;
1515

16+
/// This is a stripped down version of [`rustc_span::Span`] that only contains the start and end byte positions of the span.
17+
///
18+
/// Profiling showed that the `Span` interner was taking up a lot of the run-time when highlighting, and since we
19+
/// never actually use the context and parent that are stored in a normal `Span`, we can replace its usages with this
20+
/// one, which is much cheaper to construct.
21+
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
22+
pub(crate) struct Span {
23+
lo: BytePos,
24+
hi: BytePos,
25+
}
26+
27+
impl From<rustc_span::Span> for Span {
28+
fn from(value: rustc_span::Span) -> Self {
29+
Self { lo: value.lo(), hi: value.hi() }
30+
}
31+
}
32+
33+
impl Span {
34+
pub(crate) fn lo(self) -> BytePos {
35+
self.lo
36+
}
37+
38+
pub(crate) fn hi(self) -> BytePos {
39+
self.hi
40+
}
41+
42+
pub(crate) fn with_lo(self, lo: BytePos) -> Self {
43+
Self { lo, hi: self.hi() }
44+
}
45+
46+
pub(crate) fn with_hi(self, hi: BytePos) -> Self {
47+
Self { lo: self.lo(), hi }
48+
}
49+
}
50+
51+
pub(crate) const DUMMY_SP: Span = Span { lo: BytePos(0), hi: BytePos(0) };
52+
1653
/// This enum allows us to store two different kinds of information:
1754
///
1855
/// In case the `span` definition comes from the same crate, we can simply get the `span` and use
@@ -96,7 +133,7 @@ impl SpanMapVisitor<'_> {
96133
})
97134
.unwrap_or(path.span)
98135
};
99-
self.matches.insert(span, link);
136+
self.matches.insert(span.into(), link);
100137
}
101138
Res::Local(_) if let Some(span) = self.tcx.hir_res_span(path.res) => {
102139
let path_span = if only_use_last_segment
@@ -106,11 +143,12 @@ impl SpanMapVisitor<'_> {
106143
} else {
107144
path.span
108145
};
109-
self.matches.insert(path_span, LinkFromSrc::Local(clean::Span::new(span)));
146+
self.matches.insert(path_span.into(), LinkFromSrc::Local(clean::Span::new(span)));
110147
}
111148
Res::PrimTy(p) => {
112149
// FIXME: Doesn't handle "path-like" primitives like arrays or tuples.
113-
self.matches.insert(path.span, LinkFromSrc::Primitive(PrimitiveType::from(p)));
150+
self.matches
151+
.insert(path.span.into(), LinkFromSrc::Primitive(PrimitiveType::from(p)));
114152
}
115153
Res::Err => {}
116154
_ => {}
@@ -127,7 +165,7 @@ impl SpanMapVisitor<'_> {
127165
if cspan.inner().is_dummy() || cspan.cnum(self.tcx.sess) != LOCAL_CRATE {
128166
return;
129167
}
130-
self.matches.insert(span, LinkFromSrc::Doc(item.owner_id.to_def_id()));
168+
self.matches.insert(span.into(), LinkFromSrc::Doc(item.owner_id.to_def_id()));
131169
}
132170
}
133171

@@ -138,7 +176,7 @@ impl SpanMapVisitor<'_> {
138176
/// so, we loop until we find the macro definition by using `outer_expn_data` in a loop.
139177
/// Finally, we get the information about the macro itself (`span` if "local", `DefId`
140178
/// otherwise) and store it inside the span map.
141-
fn handle_macro(&mut self, span: Span) -> bool {
179+
fn handle_macro(&mut self, span: rustc_span::Span) -> bool {
142180
if !span.from_expansion() {
143181
return false;
144182
}
@@ -176,7 +214,7 @@ impl SpanMapVisitor<'_> {
176214
// The "call_site" includes the whole macro with its "arguments". We only want
177215
// the macro name.
178216
let new_span = new_span.with_hi(new_span.lo() + BytePos(macro_name.len() as u32));
179-
self.matches.insert(new_span, link_from_src);
217+
self.matches.insert(new_span.into(), link_from_src);
180218
true
181219
}
182220

@@ -233,7 +271,7 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
233271
intravisit::walk_path(self, path);
234272
}
235273

236-
fn visit_qpath(&mut self, qpath: &QPath<'tcx>, id: HirId, _span: Span) {
274+
fn visit_qpath(&mut self, qpath: &QPath<'tcx>, id: HirId, _span: rustc_span::Span) {
237275
match *qpath {
238276
QPath::TypeRelative(qself, path) => {
239277
if matches!(path.res, Res::Err) {
@@ -249,7 +287,7 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
249287
self.handle_path(&path, false);
250288
}
251289
} else {
252-
self.infer_id(path.hir_id, Some(id), path.ident.span);
290+
self.infer_id(path.hir_id, Some(id), path.ident.span.into());
253291
}
254292

255293
rustc_ast::visit::try_visit!(self.visit_ty_unambig(qself));
@@ -267,16 +305,18 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
267305
}
268306
}
269307

270-
fn visit_mod(&mut self, m: &'tcx Mod<'tcx>, span: Span, id: HirId) {
308+
fn visit_mod(&mut self, m: &'tcx Mod<'tcx>, span: rustc_span::Span, id: HirId) {
271309
// To make the difference between "mod foo {}" and "mod foo;". In case we "import" another
272310
// file, we want to link to it. Otherwise no need to create a link.
273311
if !span.overlaps(m.spans.inner_span) {
274312
// Now that we confirmed it's a file import, we want to get the span for the module
275313
// name only and not all the "mod foo;".
276314
if let Node::Item(item) = self.tcx.hir_node(id) {
277315
let (ident, _) = item.expect_mod();
278-
self.matches
279-
.insert(ident.span, LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)));
316+
self.matches.insert(
317+
ident.span.into(),
318+
LinkFromSrc::Local(clean::Span::new(m.spans.inner_span)),
319+
);
280320
}
281321
} else {
282322
// If it's a "mod foo {}", we want to look to its documentation page.
@@ -288,9 +328,9 @@ impl<'tcx> Visitor<'tcx> for SpanMapVisitor<'tcx> {
288328
fn visit_expr(&mut self, expr: &'tcx rustc_hir::Expr<'tcx>) {
289329
match expr.kind {
290330
ExprKind::MethodCall(segment, ..) => {
291-
self.infer_id(segment.hir_id, Some(expr.hir_id), segment.ident.span)
331+
self.infer_id(segment.hir_id, Some(expr.hir_id), segment.ident.span.into())
292332
}
293-
ExprKind::Call(call, ..) => self.infer_id(call.hir_id, None, call.span),
333+
ExprKind::Call(call, ..) => self.infer_id(call.hir_id, None, call.span.into()),
294334
_ => {
295335
if self.handle_macro(expr.span) {
296336
// We don't want to go deeper into the macro.

‎src/librustdoc/html/sources.rs‎

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -348,7 +348,12 @@ pub(crate) fn print_src(
348348
highlight::write_code(
349349
fmt,
350350
s,
351-
Some(highlight::HrefContext { context, file_span, root_path, current_href }),
351+
Some(highlight::HrefContext {
352+
context,
353+
file_span: file_span.into(),
354+
root_path,
355+
current_href,
356+
}),
352357
Some(decoration_info),
353358
Some(line_info),
354359
);

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