perf(parser): size delimited lists after the first element (#28373)

Allocate delimited lists after parsing their first element so
single-element lists use one slot and longer lists avoid the first
growth step.

AI-assisted implementation.

crates/oxc_parser/src/cursor.rs

@@ -469,13 +469,23 @@ impl<'a, C: Config> ParserImpl<'a, C> {
         close: Kind,
         separator: Kind,
         opening_span: Span,
-        parse_element: F,
+        mut parse_element: F,
     ) -> (ArenaVec<'a, T>, Option<u32>)
     where
         F: FnMut(&mut Self) -> T,
     {
-        let mut list = ArenaVec::new_in(self);
-        let trailing_separator = self.parse_delimited_list_into(
+        if self.at(close) || self.has_fatal_error() {
+            return (ArenaVec::new_in(self), None);
+        }
+        let first = parse_element(self);
+        if self.at(close) || self.has_fatal_error() {
+            let mut list = ArenaVec::with_capacity_in(1, self);
+            list.push(first);
+            return (list, None);
+        }
+        let mut list = ArenaVec::with_capacity_in(2, self);
+        list.push(first);
+        let trailing_separator = self.parse_delimited_list_rest(
             &mut list,
             close,
             separator,
@@ -503,6 +513,20 @@ impl<'a, C: Config> ParserImpl<'a, C> {
         }
         let element = parse_element(self);
         list.push(element);
+        self.parse_delimited_list_rest(list, close, separator, opening_span, parse_element)
+    }
+
+    pub(crate) fn parse_delimited_list_rest<F, T>(
+        &mut self,
+        list: &mut ArenaVec<'a, T>,
+        close: Kind,
+        separator: Kind,
+        opening_span: Span,
+        mut parse_element: F,
+    ) -> Option<u32>
+    where
+        F: FnMut(&mut Self) -> T,
+    {
         loop {
             let kind = self.cur_kind();
             if kind == close || self.has_fatal_error() {

tasks/track_memory_allocations/allocs_formatter.yaml

@@ -7,7 +7,7 @@ checker.ts:
   sys peak growth: 2973842 # 2.97 MB
   arena allocs: 36968
   arena reallocs: 927
-  arena size: 38665048 # 38.67 MB
+  arena size: 38546952 # 38.55 MB
 
 App.tsx:
   file size: 415342 # 415.34 kB
@@ -18,7 +18,7 @@ App.tsx:
   sys peak growth: 435478 # 435.48 kB
   arena allocs: 11511
   arena reallocs: 362
-  arena size: 7086616 # 7.09 MB
+  arena size: 7071288 # 7.07 MB
 
 RadixUIAdoptionSection.jsx:
   file size: 2520 # 2.52 kB
@@ -40,7 +40,7 @@ pdf.mjs:
   sys peak growth: 1156488 # 1.16 MB
   arena allocs: 21652
   arena reallocs: 402
-  arena size: 11048480 # 11.05 MB
+  arena size: 11012784 # 11.01 MB
 
 antd.js:
   file size: 6686316 # 6.69 MB
@@ -51,7 +51,7 @@ antd.js:
   sys peak growth: 13710144 # 13.71 MB
   arena allocs: 120676
   arena reallocs: 1889
-  arena size: 114754760 # 114.75 MB
+  arena size: 114439144 # 114.44 MB
 
 binder.ts:
   file size: 193077 # 193.08 kB
@@ -62,7 +62,7 @@ binder.ts:
   sys peak growth: 195197 # 195.20 kB
   arena allocs: 2092
   arena reallocs: 38
-  arena size: 2545448 # 2.55 MB
+  arena size: 2539336 # 2.54 MB
 
 kitchen-sink.tsx:
   file size: 732898 # 732.90 kB
@@ -73,4 +73,4 @@ kitchen-sink.tsx:
   sys peak growth: 1491884 # 1.49 MB
   arena allocs: 30654
   arena reallocs: 975
-  arena size: 14595272 # 14.60 MB
+  arena size: 14548696 # 14.55 MB

tasks/track_memory_allocations/allocs_minifier.yaml

@@ -7,7 +7,7 @@ checker.ts:
   sys peak growth: 10169560 # 10.17 MB
   arena allocs: 56228
   arena reallocs: 5084
-  arena size: 16501008 # 16.50 MB
+  arena size: 16382912 # 16.38 MB
 
 App.tsx:
   file size: 415342 # 415.34 kB
@@ -18,7 +18,7 @@ App.tsx:
   sys peak growth: 1612427 # 1.61 MB
   arena allocs: 7729
   arena reallocs: 920
-  arena size: 2782328 # 2.78 MB
+  arena size: 2767000 # 2.77 MB
 
 RadixUIAdoptionSection.jsx:
   file size: 2520 # 2.52 kB
@@ -40,7 +40,7 @@ pdf.mjs:
   sys peak growth: 3693355 # 3.69 MB
   arena allocs: 19582
   arena reallocs: 2574
-  arena size: 5726904 # 5.73 MB
+  arena size: 5691208 # 5.69 MB
 
 antd.js:
   file size: 6686316 # 6.69 MB
@@ -51,7 +51,7 @@ antd.js:
   sys peak growth: 19934725 # 19.93 MB
   arena allocs: 175842
   arena reallocs: 34169
-  arena size: 44039296 # 44.04 MB
+  arena size: 43723680 # 43.72 MB
 
 binder.ts:
   file size: 193077 # 193.08 kB
@@ -62,7 +62,7 @@ binder.ts:
   sys peak growth: 657404 # 657.40 kB
   arena allocs: 2930
   arena reallocs: 244
-  arena size: 1092336 # 1.09 MB
+  arena size: 1086224 # 1.09 MB
 
 kitchen-sink.tsx:
   file size: 732898 # 732.90 kB
@@ -73,4 +73,4 @@ kitchen-sink.tsx:
   sys peak growth: 3707425 # 3.71 MB
   arena allocs: 31100
   arena reallocs: 3011
-  arena size: 8460008 # 8.46 MB
+  arena size: 8413432 # 8.41 MB

tasks/track_memory_allocations/allocs_parser.yaml

@@ -6,8 +6,8 @@ checker.ts:
   sys alloc bytes: 4820 # 4.82 kB
   sys peak growth: 2432 # 2.43 kB
   arena allocs: 262590
-  arena reallocs: 22858
-  arena size: 13054768 # 13.05 MB
+  arena reallocs: 15233
+  arena size: 12936672 # 12.94 MB
 
 App.tsx:
   file size: 415342 # 415.34 kB
@@ -17,8 +17,8 @@ App.tsx:
   sys alloc bytes: 4348 # 4.35 kB
   sys peak growth: 1868 # 1.87 kB
   arena allocs: 44037
-  arena reallocs: 3537
-  arena size: 2247136 # 2.25 MB
+  arena reallocs: 2263
+  arena size: 2231808 # 2.23 MB
 
 RadixUIAdoptionSection.jsx:
   file size: 2520 # 2.52 kB
@@ -28,7 +28,7 @@ RadixUIAdoptionSection.jsx:
   sys alloc bytes: 108 # 108 B
   sys peak growth: 108 # 108 B
   arena allocs: 367
-  arena reallocs: 66
+  arena reallocs: 58
   arena size: 21200 # 21.20 kB
 
 pdf.mjs:
@@ -39,8 +39,8 @@ pdf.mjs:
   sys alloc bytes: 24020 # 24.02 kB
   sys peak growth: 12140 # 12.14 kB
   arena allocs: 89857
-  arena reallocs: 8136
-  arena size: 4553008 # 4.55 MB
+  arena reallocs: 5904
+  arena size: 4517312 # 4.52 MB
 
 antd.js:
   file size: 6686316 # 6.69 MB
@@ -50,8 +50,8 @@ antd.js:
   sys alloc bytes: 109952 # 109.95 kB
   sys peak growth: 48264 # 48.26 kB
   arena allocs: 528577
-  arena reallocs: 55355
-  arena size: 30470456 # 30.47 MB
+  arena reallocs: 35629
+  arena size: 30154616 # 30.15 MB
 
 binder.ts:
   file size: 193077 # 193.08 kB
@@ -61,8 +61,8 @@ binder.ts:
   sys alloc bytes: 3016 # 3.02 kB
   sys peak growth: 251 # 251 B
   arena allocs: 16587
-  arena reallocs: 1476
-  arena size: 924032 # 924.03 kB
+  arena reallocs: 1093
+  arena size: 917920 # 917.92 kB
 
 kitchen-sink.tsx:
   file size: 732898 # 732.90 kB
@@ -72,5 +72,5 @@ kitchen-sink.tsx:
   sys alloc bytes: 34053 # 34.05 kB
   sys peak growth: 3892 # 3.89 kB
   arena allocs: 136453
-  arena reallocs: 11898
-  arena size: 6456232 # 6.46 MB
+  arena reallocs: 8759
+  arena size: 6409648 # 6.41 MB

tasks/track_memory_allocations/allocs_semantic.yaml

@@ -7,7 +7,7 @@ checker.ts:
   sys peak growth: 3858362 # 3.86 MB
   arena allocs: 0
   arena reallocs: 0
-  arena size: 13054768 # 13.05 MB
+  arena size: 12936672 # 12.94 MB
 
 App.tsx:
   file size: 415342 # 415.34 kB
@@ -18,7 +18,7 @@ App.tsx:
   sys peak growth: 360848 # 360.85 kB
   arena allocs: 0
   arena reallocs: 0
-  arena size: 2247136 # 2.25 MB
+  arena size: 2231808 # 2.23 MB
 
 RadixUIAdoptionSection.jsx:
   file size: 2520 # 2.52 kB
@@ -40,7 +40,7 @@ pdf.mjs:
   sys peak growth: 832762 # 832.76 kB
   arena allocs: 0
   arena reallocs: 0
-  arena size: 4553008 # 4.55 MB
+  arena size: 4517312 # 4.52 MB
 
 antd.js:
   file size: 6686316 # 6.69 MB
@@ -51,7 +51,7 @@ antd.js:
   sys peak growth: 5441278 # 5.44 MB
   arena allocs: 0
   arena reallocs: 0
-  arena size: 30470456 # 30.47 MB
+  arena size: 30154616 # 30.15 MB
 
 binder.ts:
   file size: 193077 # 193.08 kB
@@ -62,7 +62,7 @@ binder.ts:
   sys peak growth: 246886 # 246.89 kB
   arena allocs: 0
   arena reallocs: 0
-  arena size: 924032 # 924.03 kB
+  arena size: 917920 # 917.92 kB
 
 kitchen-sink.tsx:
   file size: 732898 # 732.90 kB
@@ -73,4 +73,4 @@ kitchen-sink.tsx:
   sys peak growth: 1101954 # 1.10 MB
   arena allocs: 0
   arena reallocs: 0
-  arena size: 6456232 # 6.46 MB
+  arena size: 6409648 # 6.41 MB

tasks/track_memory_allocations/allocs_transformer.yaml

@@ -7,7 +7,7 @@ checker.ts:
   sys peak growth: 2243 # 2.24 kB
   arena allocs: 1959
   arena reallocs: 5
-  arena size: 13143224 # 13.14 MB
+  arena size: 13025128 # 13.03 MB
 
 App.tsx:
   file size: 415342 # 415.34 kB
@@ -18,7 +18,7 @@ App.tsx:
   sys peak growth: 2584 # 2.58 kB
   arena allocs: 618
   arena reallocs: 17
-  arena size: 2280424 # 2.28 MB
+  arena size: 2265096 # 2.27 MB
 
 RadixUIAdoptionSection.jsx:
   file size: 2520 # 2.52 kB
@@ -40,7 +40,7 @@ pdf.mjs:
   sys peak growth: 1610 # 1.61 kB
   arena allocs: 2
   arena reallocs: 0
-  arena size: 4553032 # 4.55 MB
+  arena size: 4517336 # 4.52 MB
 
 antd.js:
   file size: 6686316 # 6.69 MB
@@ -51,7 +51,7 @@ antd.js:
   sys peak growth: 1611 # 1.61 kB
   arena allocs: 2
   arena reallocs: 0
-  arena size: 30470480 # 30.47 MB
+  arena size: 30154640 # 30.15 MB
 
 binder.ts:
   file size: 193077 # 193.08 kB
@@ -62,7 +62,7 @@ binder.ts:
   sys peak growth: 1625 # 1.62 kB
   arena allocs: 154
   arena reallocs: 0
-  arena size: 930712 # 930.71 kB
+  arena size: 924600 # 924.60 kB
 
 kitchen-sink.tsx:
   file size: 732898 # 732.90 kB
@@ -73,4 +73,4 @@ kitchen-sink.tsx:
   sys peak growth: 3218 # 3.22 kB
   arena allocs: 6132
   arena reallocs: 280
-  arena size: 6790328 # 6.79 MB
+  arena size: 6743744 # 6.74 MB