Add #[bench] for librustdoc's syntax highlighter

Author: yotamofek

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

@@ -1145,7 +1145,7 @@ impl<'a> Builder<'a> {
                 test::RunMakeCargo,
             ),
             Kind::Miri => describe!(test::Crate),
-            Kind::Bench => describe!(test::Crate, test::CrateLibrustc),
+            Kind::Bench => describe!(test::Crate, test::CrateLibrustc, test::CrateRustdoc),
             Kind::Doc => describe!(
                 doc::UnstableBook,
                 doc::UnstableBookGen,

src/librustdoc/html/highlight/tests.rs

@@ -1,6 +1,7 @@
 use expect_test::expect_file;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_span::create_default_session_globals_then;
+use test::Bencher;
 
 use super::{DecorationInfo, write_code};
 
@@ -81,3 +82,16 @@ let a = 4;";
         expect_file!["fixtures/decorations.html"].assert_eq(&html);
     });
 }
+
+#[bench]
+fn bench_html_highlighting(b: &mut Bencher) {
+    let src = include_str!("../../../../compiler/rustc_ast/src/visit.rs");
+
+    create_default_session_globals_then(|| {
+        b.iter(|| {
+            let mut out = String::new();
+            write_code(&mut out, src, None, None, None);
+            out
+        });
+    });
+}