feat: splitChunks support usedExports (#7485)

* feat: splitChunks support usedExports

* docs: add docs for splitChunks.usedExports

crates/node_binding/binding.d.ts

@@ -982,6 +982,7 @@ export interface RawCacheGroupOptions {
   name?: string | false | Function
   reuseExistingChunk?: boolean
   enforce?: boolean
+  usedExports?: boolean
 }
 
 export interface RawCacheGroupTestCtx {
@@ -1666,6 +1667,7 @@ export interface RawSplitChunksOptions {
   cacheGroups?: Array<RawCacheGroupOptions>
   /** What kind of chunks should be selected. */
   chunks?: RegExp | 'async' | 'initial' | 'all' | Function
+  usedExports?: boolean
   automaticNameDelimiter?: string
   maxAsyncRequests?: number
   maxInitialRequests?: number

crates/rspack_binding_options/src/options/raw_split_chunks/mod.rs

@@ -37,6 +37,7 @@ pub struct RawSplitChunksOptions {
   #[napi(ts_type = "RegExp | 'async' | 'initial' | 'all' | Function")]
   #[derivative(Debug = "ignore")]
   pub chunks: Option<Chunks>,
+  pub used_exports: Option<bool>,
   pub automatic_name_delimiter: Option<String>,
   pub max_async_requests: Option<u32>,
   pub max_initial_requests: Option<u32>,
@@ -95,6 +96,7 @@ pub struct RawCacheGroupOptions {
   // used_exports: bool,
   pub reuse_existing_chunk: Option<bool>,
   pub enforce: Option<bool>,
+  pub used_exports: Option<bool>,
 }
 
 impl From<RawSplitChunksOptions> for rspack_plugin_split_chunks::PluginOptions {
@@ -220,6 +222,9 @@ impl From<RawSplitChunksOptions> for rspack_plugin_split_chunks::PluginOptions {
             max_initial_size,
             r#type,
             layer,
+            used_exports: v
+              .used_exports
+              .unwrap_or_else(|| raw_opts.used_exports.unwrap_or_default()),
           }
         }),
     );

crates/rspack_core/src/exports_info.rs

@@ -7,6 +7,7 @@ use std::sync::atomic::Ordering::Relaxed;
 use std::sync::Arc;
 use std::sync::LazyLock;
 
+use either::Either;
 use itertools::Itertools;
 use rspack_collections::impl_item_ukey;
 use rspack_collections::Ukey;
@@ -672,6 +673,33 @@ impl ExportsInfo {
     }
   }
 
+  pub fn get_usage_key(&self, mg: &ModuleGraph, runtime: Option<&RuntimeSpec>) -> UsageKey {
+    let exports_info = self.as_exports_info(mg);
+
+    // only expand capacity when this has redirect_to
+    let mut key = UsageKey(Vec::with_capacity(exports_info.exports.len() + 2));
+
+    if let Some(redirect_to) = &exports_info.redirect_to {
+      key.add(Either::Left(Box::new(
+        redirect_to.get_usage_key(mg, runtime),
+      )));
+    } else {
+      key.add(Either::Right(
+        self.other_exports_info(mg).get_used(mg, runtime),
+      ));
+    };
+
+    key.add(Either::Right(
+      exports_info.side_effects_only_info.get_used(mg, runtime),
+    ));
+
+    for export_info in self.ordered_exports(mg) {
+      key.add(Either::Right(export_info.get_used(mg, runtime)));
+    }
+
+    key
+  }
+
   pub fn is_used(&self, mg: &ModuleGraph, runtime: Option<&RuntimeSpec>) -> bool {
     let info = self.as_exports_info(mg);
     if let Some(redirect_to) = info.redirect_to {
@@ -1607,6 +1635,15 @@ pub struct FindTargetRetValue {
   pub export: Option<Vec<Atom>>,
 }
 
+#[derive(Debug, Hash, PartialEq, Eq, Default)]
+pub struct UsageKey(pub(crate) Vec<Either<Box<UsageKey>, UsageState>>);
+
+impl UsageKey {
+  fn add(&mut self, value: Either<Box<UsageKey>, UsageState>) {
+    self.0.push(value);
+  }
+}
+
 #[derive(Debug, Clone)]
 struct UnResolvedExportInfoTarget {
   connection: Option<DependencyId>,

crates/rspack_plugin_split_chunks/src/options/cache_group.rs

@@ -42,4 +42,5 @@ pub struct CacheGroup {
   pub max_initial_size: SplitChunkSizes,
   pub filename: Option<Filename>,
   pub automatic_name_delimiter: String,
+  pub used_exports: bool,
 }