fix(es/transforms/compat): Improve performance (#1673)

swc_ecma_transforms_compat:
 - `classes`: Fast-path.
 - `destructuring`: Fast-path.
 - `sticky_regex`: Fast-path.
 - `spread`: Fast-path.
 - `shorthand`: Fast-path.
 - `typeof_symbol`: Fast-path.
 - `block_scoped_functions`: Fast path.
 - `duplicate_keys`: Use fxhash.
 - `instance_of`: Fast path.
 - `reserved_words`: Make string comparison efficient.

Author: kdy1

atoms/src/lib.rs

@@ -1,3 +1,13 @@
+//! [JsWord] is an interened string.
+//!
+//! This type should be used instead of [String] for values, because lots of
+//! values are duplicated. For example, if an identifer is named `myVariable`,
+//! there will be lots of identifier usages with the value `myVariable`.
+//!
+//! This type
+//!  - makes equality comparison faster.
+//!  - reduces memory usage.
+
 #![allow(clippy::unreadable_literal)]
 
 include!(concat!(env!("OUT_DIR"), "/js_word.rs"));

common/src/syntax_pos.rs

@@ -63,7 +63,20 @@ impl Globals {
     }
 }
 
-// scoped_thread_local!(pub static GLOBALS: Globals);
+/// Storage for span hygiene data.
+///
+/// This variable is used to manage identifiers or to identify nodes.
+/// Note that it's stored as a thread-local storage, but actually it's shared
+/// between threads.
+///
+/// # Usages
+///
+/// ## Span hygiene
+///
+/// [Mark]s are stored in this variable.
+///
+/// You can see the document how swc uses the span hygiene info at
+/// https://rustdoc.swc.rs/swc_ecma_transforms_base/resolver/fn.resolver_with_mark.html
 pub static GLOBALS: ::scoped_tls::ScopedKey<Globals> = ::scoped_tls::ScopedKey {
     inner: {
         thread_local!(static FOO: ::std::cell::Cell<usize> = {

ecmascript/parser/benches/parser.rs

@@ -2,6 +2,7 @@
 
 extern crate test;
 
+use swc_common::comments::SingleThreadedComments;
 use swc_common::FileName;
 use swc_ecma_parser::{lexer::Lexer, Parser, StringInput, Syntax};
 use test::Bencher;
@@ -71,97 +72,21 @@ fn yui(b: &mut Bencher) {
     bench_module(b, Default::default(), include_str!("./files/yui-3.12.0.js"))
 }
 
-#[bench]
-fn colors_ts(b: &mut Bencher) {
-    // Copied from ratel-rust
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("../colors.js"),
-    )
-}
-
-#[bench]
-fn angular_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/angular-1.2.5.js"),
-    )
-}
-
-#[bench]
-fn backbone_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/backbone-1.1.0.js"),
-    )
-}
-
-#[bench]
-fn jquery_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/jquery-1.9.1.js"),
-    )
-}
-
-#[bench]
-fn jquery_mobile_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/jquery.mobile-1.4.2.js"),
-    )
-}
-
-#[bench]
-fn mootools_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/mootools-1.4.5.js"),
-    )
-}
-
-#[bench]
-fn underscore_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/underscore-1.5.2.js"),
-    )
-}
-
-#[bench]
-fn yui_ts(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("./files/yui-3.12.0.js"),
-    )
-}
-
-#[bench]
-fn large(b: &mut Bencher) {
-    bench_module(
-        b,
-        Syntax::Typescript(Default::default()),
-        include_str!("../../codegen/benches/large-partial.js"),
-    )
-}
-
 fn bench_module(b: &mut Bencher, syntax: Syntax, src: &'static str) {
     b.bytes = src.len() as _;
 
     let _ = ::testing::run_test(false, |cm, _| {
+        let comments = SingleThreadedComments::default();
         let fm = cm.new_source_file(FileName::Anon, src.into());
 
         b.iter(|| {
             let _ = test::black_box({
-                let lexer = Lexer::new(syntax, Default::default(), StringInput::from(&*fm), None);
+                let lexer = Lexer::new(
+                    syntax,
+                    Default::default(),
+                    StringInput::from(&*fm),
+                    Some(&comments),
+                );
                 let mut parser = Parser::new_from(lexer);
                 parser.parse_module()
             });

ecmascript/transforms/base/src/helpers/mod.rs

@@ -60,7 +60,12 @@ macro_rules! add_to {
     }};
 }
 
-scoped_thread_local!(pub static HELPERS: Helpers);
+scoped_thread_local!(
+    /// This variable is used to manage helper scripts like `_inherits` from babel.
+    ///
+    /// The instance contains flags where each flag denotes if a helper script should be injected.
+    pub static HELPERS: Helpers
+);
 
 /// Tracks used helper methods. (e.g. __extends)
 #[derive(Debug, Default)]

ecmascript/transforms/compat/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2018"
 license = "Apache-2.0/MIT"
 name = "swc_ecma_transforms_compat"
 repository = "https://github.com/swc-project/swc.git"
-version = "0.16.1"
+version = "0.16.2"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]

ecmascript/transforms/compat/src/es2015/block_scoped_fn.rs

@@ -1,6 +1,12 @@
 use swc_common::{Spanned, DUMMY_SP};
 use swc_ecma_ast::*;
+use swc_ecma_transforms_base::perf::Check;
+use swc_ecma_transforms_macros::fast_path;
 use swc_ecma_utils::UsageFinder;
+use swc_ecma_visit::noop_visit_type;
+use swc_ecma_visit::Node;
+use swc_ecma_visit::Visit;
+use swc_ecma_visit::VisitWith;
 use swc_ecma_visit::{noop_fold_type, Fold, FoldWith};
 
 pub fn block_scoped_functions() -> impl Fold {
@@ -10,6 +16,7 @@ pub fn block_scoped_functions() -> impl Fold {
 #[derive(Clone, Copy)]
 struct BlockScopedFns;
 
+#[fast_path(BlockScopedFnFinder)]
 impl Fold for BlockScopedFns {
     noop_fold_type!();
 
@@ -61,6 +68,32 @@ impl Fold for BlockScopedFns {
     }
 }
 
+#[derive(Default)]
+struct BlockScopedFnFinder {
+    found: bool,
+}
+
+impl Visit for BlockScopedFnFinder {
+    noop_visit_type!();
+
+    fn visit_stmts(&mut self, stmts: &[Stmt], _: &dyn Node) {
+        for n in stmts {
+            n.visit_with(&Invalid { span: DUMMY_SP }, self);
+        }
+
+        self.found |= stmts.iter().any(|stmt| match stmt {
+            Stmt::Decl(Decl::Fn(..)) => true,
+            _ => false,
+        });
+    }
+}
+
+impl Check for BlockScopedFnFinder {
+    fn should_handle(&self) -> bool {
+        self.found
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

ecmascript/transforms/compat/src/es2015/classes/mod.rs

@@ -13,6 +13,8 @@ use swc_common::{Mark, Spanned, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::helper;
 use swc_ecma_transforms_base::native::is_native;
+use swc_ecma_transforms_base::perf::Check;
+use swc_ecma_transforms_macros::fast_path;
 use swc_ecma_utils::quote_expr;
 use swc_ecma_utils::quote_str;
 use swc_ecma_utils::{
@@ -187,6 +189,7 @@ where
     }
 }
 
+#[fast_path(ClassFinder)]
 impl<C> Fold for Classes<C>
 where
     C: Comments,
@@ -202,26 +205,6 @@ where
     }
 
     fn fold_decl(&mut self, n: Decl) -> Decl {
-        fn should_work(node: &Decl) -> bool {
-            struct Visitor {
-                found: bool,
-            }
-            impl Visit for Visitor {
-                noop_visit_type!();
-
-                fn visit_class(&mut self, _: &Class, _: &dyn Node) {
-                    self.found = true
-                }
-            }
-            let mut v = Visitor { found: false };
-            node.visit_with(&Invalid { span: DUMMY_SP } as _, &mut v);
-            v.found
-        }
-        // fast path
-        if !should_work(&n) {
-            return n;
-        }
-
         let n = match n {
             Decl::Class(decl) => Decl::Var(self.fold_class_as_var_decl(decl.ident, decl.class)),
             _ => n,
@@ -968,3 +951,22 @@ fn escape_keywords(mut e: Box<Expr>) -> Box<Expr> {
 
     e
 }
+
+#[derive(Default)]
+struct ClassFinder {
+    found: bool,
+}
+
+impl Visit for ClassFinder {
+    noop_visit_type!();
+
+    fn visit_class(&mut self, _: &Class, _: &dyn Node) {
+        self.found = true
+    }
+}
+
+impl Check for ClassFinder {
+    fn should_handle(&self) -> bool {
+        self.found
+    }
+}

ecmascript/transforms/compat/src/es2015/destructuring.rs

@@ -3,6 +3,8 @@ use std::iter;
 use swc_common::{Spanned, SyntaxContext, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::helper;
+use swc_ecma_transforms_base::perf::Check;
+use swc_ecma_transforms_macros::fast_path;
 use swc_ecma_utils::alias_ident_for;
 use swc_ecma_utils::alias_if_required;
 use swc_ecma_utils::has_rest_pat;
@@ -454,6 +456,7 @@ impl AssignFolder {
     }
 }
 
+#[fast_path(DestructuringVisitor)]
 impl Fold for Destructuring {
     noop_fold_type!();
 
@@ -527,6 +530,7 @@ struct AssignFolder {
     ignore_return_value: Option<()>,
 }
 
+#[fast_path(DestructuringVisitor)]
 impl Fold for AssignFolder {
     noop_fold_type!();
 
@@ -1129,6 +1133,7 @@ where
     v.found
 }
 
+#[derive(Default)]
 struct DestructuringVisitor {
     found: bool,
 }
@@ -1144,3 +1149,9 @@ impl Visit for DestructuringVisitor {
         }
     }
 }
+
+impl Check for DestructuringVisitor {
+    fn should_handle(&self) -> bool {
+        self.found
+    }
+}

ecmascript/transforms/compat/src/es2015/duplicate_keys.rs

@@ -1,4 +1,4 @@
-use std::collections::HashSet;
+use fxhash::FxHashSet;
 use swc_atoms::JsWord;
 use swc_common::Spanned;
 use swc_ecma_ast::*;
@@ -34,8 +34,8 @@ impl Fold for DuplicateKeys {
 
 #[derive(Default)]
 struct PropFolder {
-    getter_props: HashSet<JsWord>,
-    setter_props: HashSet<JsWord>,
+    getter_props: FxHashSet<JsWord>,
+    setter_props: FxHashSet<JsWord>,
 }
 
 impl Fold for PropFolder {
@@ -85,7 +85,7 @@ impl Fold for PropFolder {
 }
 
 struct PropNameFolder<'a> {
-    props: &'a mut HashSet<JsWord>,
+    props: &'a mut FxHashSet<JsWord>,
 }
 impl<'a> Fold for PropNameFolder<'a> {
     noop_fold_type!();