Improve packed field decoding

benchmarks/bin/binary_decode_packed.dart

@@ -0,0 +1,171 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:math';
+import 'dart:typed_data';
+
+import 'package:fixnum/fixnum.dart';
+import 'package:protobuf_benchmarks/benchmark_base.dart';
+import 'package:protobuf_benchmarks/generated/packed_fields.pb.dart';
+
+PackedFields? sink;
+
+class PackedInt32DecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedInt32DecodingBenchmark() : super('PackedInt32Decoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      message.packedInt32.add(rand.nextInt(2147483647));
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedInt64DecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedInt64DecodingBenchmark() : super('PackedInt64Decoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      // Note: `Random` cannot generate more than the number below.
+      message.packedInt64.add(Int64(rand.nextInt(4294967296)));
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedUint32DecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedUint32DecodingBenchmark() : super('PackedUint32Decoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      message.packedUint32.add(rand.nextInt(4294967295));
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedUint64DecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedUint64DecodingBenchmark() : super('PackedUint64Decoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      // Note: `Random` cannot generate more than the number below.
+      message.packedUint64.add(Int64(rand.nextInt(4294967296)));
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedSint32DecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedSint32DecodingBenchmark() : super('PackedSint32Decoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      message.packedSint32.add(rand.nextInt(2147483647));
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedSint64DecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedSint64DecodingBenchmark() : super('PackedSint64Decoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      // Note: `Random` cannot generate more than the number below.
+      message.packedSint64.add(Int64(rand.nextInt(4294967296)));
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedBoolDecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedBoolDecodingBenchmark() : super('PackedBoolDecoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    for (var i = 0; i < 1000000; i += 1) {
+      message.packedBool.add(rand.nextBool());
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+class PackedEnumDecodingBenchmark extends BenchmarkBase {
+  late final Uint8List encoded;
+
+  PackedEnumDecodingBenchmark() : super('PackedEnumDecoding') {
+    final rand = Random(123);
+    final message = PackedFields();
+    final numEnums = Enum.values.length;
+    for (var i = 0; i < 1000000; i += 1) {
+      message.packedEnum.add(Enum.values[rand.nextInt(numEnums)]);
+    }
+    encoded = message.writeToBuffer();
+  }
+
+  @override
+  void run() {
+    sink = PackedFields()..mergeFromBuffer(encoded);
+  }
+}
+
+void main() {
+  PackedInt32DecodingBenchmark().report();
+  PackedInt64DecodingBenchmark().report();
+  PackedUint32DecodingBenchmark().report();
+  PackedUint64DecodingBenchmark().report();
+  PackedSint32DecodingBenchmark().report();
+  PackedSint64DecodingBenchmark().report();
+  PackedBoolDecodingBenchmark().report();
+  PackedEnumDecodingBenchmark().report();
+}

benchmarks/protos/packed_fields.proto

@@ -0,0 +1,20 @@
+syntax = "proto3";
+
+message PackedFields {
+    repeated int32 packedInt32 = 1 [packed = true];
+    repeated int64 packedInt64 = 2 [packed = true];
+    repeated uint32 packedUint32 = 3 [packed = true];
+    repeated uint64 packedUint64 = 4 [packed = true];
+    repeated sint32 packedSint32 = 5 [packed = true];
+    repeated sint64 packedSint64 = 6 [packed = true];
+    repeated bool packedBool = 7 [packed = true];
+    repeated Enum packedEnum = 8 [packed = true];
+}
+
+enum Enum {
+  ENUM_1 = 0;
+  ENUM_2 = 1;
+  ENUM_3 = 2;
+  ENUM_4 = 4;
+  ENUM_5 = 5;
+}

benchmarks/tool/compile_protos.sh

@@ -12,6 +12,7 @@ SIMPLE_PROTOS=(
     "protos/google_message1_proto2.proto"
     "protos/google_message1_proto3.proto"
     "protos/google_message2.proto"
+    "protos/packed_fields.proto"
 )
 
 set -x