switched to a double variant of clamp to avoid boxing (#103559)

Author: gaaclarke

dev/benchmarks/microbenchmarks/lib/foundation/clamp.dart

@@ -0,0 +1,73 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart' show clampDouble;
+
+import '../common.dart';
+
+const int _kBatchSize = 100000;
+const int _kNumIterations = 1000;
+
+void main() {
+  assert(false,
+      "Don't run benchmarks in debug mode! Use 'flutter run --release'.");
+  final BenchmarkResultPrinter printer = BenchmarkResultPrinter();
+
+  final Stopwatch watch = Stopwatch();
+  {
+    final List<double> clampDoubleValues = <double>[];
+    for (int j = 0; j < _kNumIterations; ++j) {
+      double tally = 0;
+      watch.reset();
+      watch.start();
+      for (int i = 0; i < _kBatchSize; i += 1) {
+        tally += clampDouble(-1.0, 0.0, 1.0);
+        tally += clampDouble(2.0, 0.0, 1.0);
+        tally += clampDouble(0.0, 0.0, 1.0);
+        tally += clampDouble(double.nan, 0.0, 1.0);
+      }
+      watch.stop();
+      clampDoubleValues.add(watch.elapsedMicroseconds.toDouble() / _kBatchSize);
+      if (tally < 0.0) {
+        print("This shouldn't happen.");
+      }
+    }
+
+    printer.addResultStatistics(
+      description: 'clamp - clampDouble',
+      values: clampDoubleValues,
+      unit: 'us per iteration',
+      name: 'clamp_clampDouble',
+    );
+  }
+
+  {
+    final List<double> doubleClampValues = <double>[];
+
+    for (int j = 0; j < _kNumIterations; ++j) {
+      double tally = 0;
+      watch.reset();
+      watch.start();
+      for (int i = 0; i < _kBatchSize; i += 1) {
+        tally += -1.0.clamp(0.0, 1.0);
+        tally += 2.0.clamp(0.0, 1.0);
+        tally += 0.0.clamp(0.0, 1.0);
+        tally += double.nan.clamp(0.0, 1.0);
+      }
+      watch.stop();
+      doubleClampValues.add(watch.elapsedMicroseconds.toDouble() / _kBatchSize);
+      if (tally < 0.0) {
+        print("This shouldn't happen.");
+      }
+    }
+
+    printer.addResultStatistics(
+      description: 'clamp - Double.clamp',
+      values: doubleClampValues,
+      unit: 'us per iteration',
+      name: 'clamp_Double_clamp',
+    );
+  }
+  printer.printToStdout();
+}

dev/bots/analyze.dart

@@ -88,6 +88,9 @@ Future<void> run(List<String> arguments) async {
     exitWithError(<String>['The analyze.dart script must be run with --enable-asserts.']);
   }
 
+  print('$clock No Double.clamp');
+  await verifyNoDoubleClamp(flutterRoot);
+
   print('$clock All tool test files end in _test.dart...');
   await verifyToolTestsEndInTestDart(flutterRoot);
 
@@ -203,6 +206,80 @@ Future<void> run(List<String> arguments) async {
 
 // TESTS
 
+FeatureSet _parsingFeatureSet() => FeatureSet.fromEnableFlags2(
+    sdkLanguageVersion: Version.parse('2.17.0-0'),
+    flags: <String>['super-parameters']);
+
+_Line _getLine(ParseStringResult parseResult, int offset) {
+  final int lineNumber =
+      parseResult.lineInfo.getLocation(offset).lineNumber;
+  final String content = parseResult.content.substring(
+      parseResult.lineInfo.getOffsetOfLine(lineNumber - 1),
+      parseResult.lineInfo.getOffsetOfLine(lineNumber) - 1);
+  return _Line(lineNumber, content);
+}
+
+class _DoubleClampVisitor extends RecursiveAstVisitor<CompilationUnit> {
+  _DoubleClampVisitor(this.parseResult);
+
+  final List<_Line> clamps = <_Line>[];
+  final ParseStringResult parseResult;
+
+  @override
+  CompilationUnit? visitMethodInvocation(MethodInvocation node) {
+    if (node.methodName.name == 'clamp') {
+      final _Line line = _getLine(parseResult, node.function.offset);
+      if (!line.content.contains('// ignore_clamp_double_lint')) {
+        clamps.add(line);
+      }
+    }
+
+    node.visitChildren(this);
+    return null;
+  }
+}
+
+/// Verify that we use clampDouble instead of Double.clamp for performance reasons.
+///
+/// We currently can't distinguish valid uses of clamp from problematic ones so
+/// if the clamp is operating on a type other than a `double` the
+/// `// ignore_clamp_double_lint` comment must be added to the line where clamp is
+/// invoked.
+///
+/// See also:
+///   * https://github.com/flutter/flutter/pull/103559
+///   * https://github.com/flutter/flutter/issues/103917
+Future<void> verifyNoDoubleClamp(String workingDirectory) async {
+  final String flutterLibPath = '$workingDirectory/packages/flutter/lib';
+  final Stream<File> testFiles =
+      _allFiles(flutterLibPath, 'dart', minimumMatches: 100);
+  final List<String> errors = <String>[];
+  await for (final File file in testFiles) {
+    try {
+      final ParseStringResult parseResult = parseFile(
+        featureSet: _parsingFeatureSet(),
+        path: file.absolute.path,
+      );
+      final _DoubleClampVisitor visitor = _DoubleClampVisitor(parseResult);
+      visitor.visitCompilationUnit(parseResult.unit);
+      for (final _Line clamp in visitor.clamps) {
+        errors.add('${file.path}:${clamp.line}: `clamp` method used without ignore_clamp_double_lint comment.');
+      }
+    } catch (ex) {
+      // TODO(gaaclarke): There is a bug with super parameter parsing on mac so
+      // we skip certain files until that is fixed.
+      // https://github.com/dart-lang/sdk/issues/49032
+      print('skipping ${file.path}: $ex');
+    }
+  }
+  if (errors.isNotEmpty) {
+    exitWithError(<String>[
+      ...errors,
+      '\n${bold}See: https://github.com/flutter/flutter/pull/103559',
+    ]);
+  }
+}
+
 /// Verify tool test files end in `_test.dart`.
 ///
 /// The test runner will only recognize files ending in `_test.dart` as tests to
@@ -518,16 +595,16 @@ Future<int> _verifyNoMissingLicenseForExtension(
   return 0;
 }
 
-class _TestSkip {
-  _TestSkip(this.line, this.content);
+class _Line {
+  _Line(this.line, this.content);
 
   final int line;
   final String content;
 }
 
-Iterable<_TestSkip> _getTestSkips(File file) {
+Iterable<_Line> _getTestSkips(File file) {
   final ParseStringResult parseResult = parseFile(
-    featureSet: FeatureSet.fromEnableFlags2(sdkLanguageVersion: Version.parse('2.17.0-0'), flags: <String>['super-parameters']),
+    featureSet: _parsingFeatureSet(),
     path: file.absolute.path,
   );
   final _TestSkipLinesVisitor<CompilationUnit> visitor = _TestSkipLinesVisitor<CompilationUnit>(parseResult);
@@ -536,10 +613,10 @@ Iterable<_TestSkip> _getTestSkips(File file) {
 }
 
 class _TestSkipLinesVisitor<T> extends RecursiveAstVisitor<T> {
-  _TestSkipLinesVisitor(this.parseResult) : skips = <_TestSkip>{};
+  _TestSkipLinesVisitor(this.parseResult) : skips = <_Line>{};
 
   final ParseStringResult parseResult;
-  final Set<_TestSkip> skips;
+  final Set<_Line> skips;
 
   static bool isTestMethod(String name) {
     return name.startsWith('test') || name == 'group' || name == 'expect';
@@ -550,10 +627,7 @@ class _TestSkipLinesVisitor<T> extends RecursiveAstVisitor<T> {
     if (isTestMethod(node.methodName.toString())) {
       for (final Expression argument in node.argumentList.arguments) {
         if (argument is NamedExpression && argument.name.label.name == 'skip') {
-          final int lineNumber = parseResult.lineInfo.getLocation(argument.beginToken.charOffset).lineNumber;
-          final String content = parseResult.content.substring(parseResult.lineInfo.getOffsetOfLine(lineNumber - 1),
-                                                               parseResult.lineInfo.getOffsetOfLine(lineNumber) - 1);
-          skips.add(_TestSkip(lineNumber, content));
+          skips.add(_getLine(parseResult, argument.beginToken.charOffset));
         }
       }
     }
@@ -571,7 +645,7 @@ Future<void> verifySkipTestComments(String workingDirectory) async {
     .where((File f) => f.path.endsWith('_test.dart'));
 
   await for (final File file in testFiles) {
-    for (final _TestSkip skip in _getTestSkips(file)) {
+    for (final _Line skip in _getTestSkips(file)) {
       final Match? match = _skipTestCommentPattern.firstMatch(skip.content);
       final String? skipComment = match?.group(1);
       if (skipComment == null ||

dev/devicelab/lib/tasks/microbenchmarks.dart

@@ -60,6 +60,7 @@ TaskFunction createMicrobenchmarkTask() {
       ...await runMicrobench('lib/language/sync_star_bench.dart'),
       ...await runMicrobench('lib/language/sync_star_semantics_bench.dart'),
       ...await runMicrobench('lib/foundation/all_elements_bench.dart'),
+      ...await runMicrobench('lib/foundation/clamp.dart'),
       ...await runMicrobench('lib/foundation/change_notifier_bench.dart'),
       ...await runMicrobench('lib/foundation/standard_method_codec_bench.dart'),
       ...await runMicrobench('lib/foundation/standard_message_codec_bench.dart'),

packages/flutter/lib/foundation.dart

@@ -33,6 +33,7 @@ export 'src/foundation/diagnostics.dart';
 export 'src/foundation/isolates.dart';
 export 'src/foundation/key.dart';
 export 'src/foundation/licenses.dart';
+export 'src/foundation/math.dart';
 export 'src/foundation/node.dart';
 export 'src/foundation/object.dart';
 export 'src/foundation/observer_list.dart';

packages/flutter/lib/src/animation/animation_controller.dart

@@ -395,7 +395,7 @@ class AnimationController extends Animation<double>
   }
 
   void _internalSetValue(double newValue) {
-    _value = newValue.clamp(lowerBound, upperBound);
+    _value = clampDouble(newValue, lowerBound, upperBound);
     if (_value == lowerBound) {
       _status = AnimationStatus.dismissed;
     } else if (_value == upperBound) {
@@ -598,7 +598,7 @@ class AnimationController extends Animation<double>
     stop();
     if (simulationDuration == Duration.zero) {
       if (value != target) {
-        _value = target.clamp(lowerBound, upperBound);
+        _value = clampDouble(target, lowerBound, upperBound);
         notifyListeners();
       }
       _status = (_direction == _AnimationDirection.forward) ?
@@ -741,7 +741,7 @@ class AnimationController extends Animation<double>
     assert(!isAnimating);
     _simulation = simulation;
     _lastElapsedDuration = Duration.zero;
-    _value = simulation.x(0.0).clamp(lowerBound, upperBound);
+    _value = clampDouble(simulation.x(0.0), lowerBound, upperBound);
     final TickerFuture result = _ticker!.start();
     _status = (_direction == _AnimationDirection.forward) ?
       AnimationStatus.forward :
@@ -820,7 +820,7 @@ class AnimationController extends Animation<double>
     _lastElapsedDuration = elapsed;
     final double elapsedInSeconds = elapsed.inMicroseconds.toDouble() / Duration.microsecondsPerSecond;
     assert(elapsedInSeconds >= 0.0);
-    _value = _simulation!.x(elapsedInSeconds).clamp(lowerBound, upperBound);
+    _value = clampDouble(_simulation!.x(elapsedInSeconds), lowerBound, upperBound);
     if (_simulation!.isDone(elapsedInSeconds)) {
       _status = (_direction == _AnimationDirection.forward) ?
         AnimationStatus.completed :
@@ -855,7 +855,7 @@ class _InterpolationSimulation extends Simulation {
 
   @override
   double x(double timeInSeconds) {
-    final double t = (timeInSeconds / _durationInSeconds).clamp(0.0, 1.0);
+    final double t = clampDouble(timeInSeconds / _durationInSeconds, 0.0, 1.0);
     if (t == 0.0)
       return _begin;
     else if (t == 1.0)

packages/flutter/lib/src/animation/curves.dart

@@ -182,7 +182,7 @@ class Interval extends Curve {
     assert(end >= 0.0);
     assert(end <= 1.0);
     assert(end >= begin);
-    t = ((t - begin) / (end - begin)).clamp(0.0, 1.0);
+    t = clampDouble((t - begin) / (end - begin), 0.0, 1.0);
     if (t == 0.0 || t == 1.0)
       return t;
     return curve.transform(t);

packages/flutter/lib/src/cupertino/context_menu.dart

@@ -4,6 +4,7 @@
 
 import 'dart:math' as math;
 import 'dart:ui' as ui;
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart' show kMinFlingVelocity, kLongPressTimeout;
 import 'package:flutter/scheduler.dart';
@@ -958,7 +959,7 @@ class _ContextMenuRouteStaticState extends State<_ContextMenuRouteStatic> with T
       _moveAnimation = Tween<Offset>(
         begin: Offset.zero,
         end: Offset(
-          endX.clamp(-_kPadding, _kPadding),
+          clampDouble(endX, -_kPadding, _kPadding),
           endY,
         ),
       ).animate(

packages/flutter/lib/src/cupertino/desktop_text_selection.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart' show clampDouble;
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
@@ -157,7 +158,7 @@ class _CupertinoDesktopTextSelectionControlsToolbarState extends State<_Cupertin
     final MediaQueryData mediaQuery = MediaQuery.of(context);
 
     final Offset midpointAnchor = Offset(
-      (widget.selectionMidpoint.dx - widget.globalEditableRegion.left).clamp(
+      clampDouble(widget.selectionMidpoint.dx - widget.globalEditableRegion.left,
         mediaQuery.padding.left,
         mediaQuery.size.width - mediaQuery.padding.right,
       ),

packages/flutter/lib/src/cupertino/refresh.dart

@@ -4,6 +4,7 @@
 
 import 'dart:math';
 
+import 'package:flutter/foundation.dart' show clampDouble;
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
@@ -375,7 +376,7 @@ class CupertinoSliverRefreshControl extends StatefulWidget {
     double refreshTriggerPullDistance,
     double refreshIndicatorExtent,
   ) {
-    final double percentageComplete = (pulledExtent / refreshTriggerPullDistance).clamp(0.0, 1.0);
+    final double percentageComplete = clampDouble(pulledExtent / refreshTriggerPullDistance, 0.0, 1.0);
 
     // Place the indicator at the top of the sliver that opens up. Note that we're using
     // a Stack/Positioned widget because the CupertinoActivityIndicator does some internal

packages/flutter/lib/src/cupertino/slider.dart

@@ -5,6 +5,7 @@
 import 'dart:math' as math;
 import 'dart:ui' show lerpDouble;
 
+import 'package:flutter/foundation.dart' show clampDouble;
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
@@ -434,7 +435,7 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
   double _currentDragValue = 0.0;
 
   double get _discretizedCurrentDragValue {
-    double dragValue = _currentDragValue.clamp(0.0, 1.0);
+    double dragValue = clampDouble(_currentDragValue, 0.0, 1.0);
     if (divisions != null)
       dragValue = (dragValue * divisions!).round() / divisions!;
     return dragValue;
@@ -554,20 +555,20 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
       config.onIncrease = _increaseAction;
       config.onDecrease = _decreaseAction;
       config.value = '${(value * 100).round()}%';
-      config.increasedValue = '${((value + _semanticActionUnit).clamp(0.0, 1.0) * 100).round()}%';
-      config.decreasedValue = '${((value - _semanticActionUnit).clamp(0.0, 1.0) * 100).round()}%';
+      config.increasedValue = '${(clampDouble(value + _semanticActionUnit, 0.0, 1.0) * 100).round()}%';
+      config.decreasedValue = '${(clampDouble(value - _semanticActionUnit, 0.0, 1.0) * 100).round()}%';
     }
   }
 
   double get _semanticActionUnit => divisions != null ? 1.0 / divisions! : _kAdjustmentUnit;
 
   void _increaseAction() {
     if (isInteractive)
-      onChanged!((value + _semanticActionUnit).clamp(0.0, 1.0));
+      onChanged!(clampDouble(value + _semanticActionUnit, 0.0, 1.0));
   }
 
   void _decreaseAction() {
     if (isInteractive)
-      onChanged!((value - _semanticActionUnit).clamp(0.0, 1.0));
+      onChanged!(clampDouble(value - _semanticActionUnit, 0.0, 1.0));
   }
 }