[dart2js] Migrate ssa/jump_handler.dart to null safety.

Change-Id: I23475740209738302e17ef298394bccb847a341f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/277060
Commit-Queue: Nate Biggs <[email protected]>
Reviewed-by: Sigmund Cherem <[email protected]>

Author: natebiggs

pkg/compiler/lib/src/ssa/builder.dart

@@ -2368,8 +2368,8 @@ class KernelSsaGraphBuilder extends ir.Visitor<void>
       HBasicBlock conditionBlock = addNewBlock();
 
       List<LocalsHandler> continueHandlers = <LocalsHandler>[];
-      jumpHandler.forEachContinue(
-          (HContinue instruction, interfaces.LocalsHandler locals) {
+      jumpHandler
+          .forEachContinue((HContinue instruction, LocalsHandler locals) {
         instruction.block.addSuccessor(conditionBlock);
         continueHandlers.add(locals);
       });
@@ -2724,8 +2724,7 @@ class KernelSsaGraphBuilder extends ir.Visitor<void>
 
     HBasicBlock joinBlock = graph.addNewBlock();
     List<LocalsHandler> breakHandlers = [];
-    handler.forEachBreak(
-        (HBreak breakInstruction, interfaces.LocalsHandler locals) {
+    handler.forEachBreak((HBreak breakInstruction, LocalsHandler locals) {
       breakInstruction.block.addSuccessor(joinBlock);
       breakHandlers.add(locals);
     });
@@ -3072,13 +3071,11 @@ class KernelSsaGraphBuilder extends ir.Visitor<void>
     // the join block is never added to the graph.
     HBasicBlock joinBlock = HBasicBlock();
     List<LocalsHandler> caseHandlers = [];
-    jumpHandler
-        .forEachBreak((HBreak instruction, interfaces.LocalsHandler locals) {
+    jumpHandler.forEachBreak((HBreak instruction, LocalsHandler locals) {
       instruction.block.addSuccessor(joinBlock);
       caseHandlers.add(locals);
     });
-    jumpHandler.forEachContinue(
-        (HContinue instruction, interfaces.LocalsHandler locals) {
+    jumpHandler.forEachContinue((HContinue instruction, LocalsHandler locals) {
       assert(
           false,
           failedAt(_elementMap.getSpannable(targetElement, switchStatement),

pkg/compiler/lib/src/ssa/builder_interfaces.dart

@@ -2,7 +2,6 @@
 // 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 'package:compiler/src/elements/types.dart';
 import 'package:compiler/src/options.dart';
 import 'package:kernel/ast.dart' as ir;
 
@@ -12,9 +11,10 @@ import '../elements/entities.dart';
 import '../elements/jumps.dart';
 import '../inferrer/abstract_value_domain.dart';
 import '../inferrer/types.dart';
-import '../io/source_information.dart';
 import '../js_model/js_world.dart';
 import 'nodes.dart';
+import 'jump_handler.dart';
+import 'locals_handler.dart';
 
 abstract class KernelSsaGraphBuilder extends ir.Visitor<void> {
   JClosedWorld get closedWorld;
@@ -53,31 +53,3 @@ abstract class KernelSsaGraphBuilder extends ir.Visitor<void> {
 
   HInstruction pop();
 }
-
-abstract class JumpHandler {
-  void generateBreak(SourceInformation sourceInformation,
-      [LabelDefinition label]);
-  void generateContinue(SourceInformation sourceInformation,
-      [LabelDefinition label]);
-  void forEachBreak(void action(HBreak instruction, LocalsHandler locals));
-  void forEachContinue(
-      void action(HContinue instruction, LocalsHandler locals));
-  bool hasAnyContinue();
-  bool hasAnyBreak();
-  void close();
-  JumpTarget get target;
-  List<LabelDefinition> get labels;
-}
-
-abstract class LocalsHandler {
-  void updateLocal(JumpTarget target, HInstruction value);
-
-  DartType substInContext(DartType type);
-
-  HInstruction readThis({SourceInformation? sourceInformation});
-
-  Local getTypeVariableAsLocal(TypeVariableType parameter);
-
-  HInstruction readLocal(Local typeVariableLocal,
-      {SourceInformation? sourceInformation});
-}

pkg/compiler/lib/src/ssa/jump_handler.dart

@@ -2,8 +2,6 @@
 // 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.
 
-// @dart = 2.10
-
 import '../common.dart';
 import '../elements/jumps.dart';
 import '../inferrer/abstract_value_domain.dart';
@@ -22,11 +20,24 @@ class _JumpHandlerEntry {
   _JumpHandlerEntry(this.jumpInstruction, this.locals);
 }
 
-abstract class JumpHandler extends interfaces.JumpHandler {
+abstract class JumpHandler {
   factory JumpHandler(
       interfaces.KernelSsaGraphBuilder builder, JumpTarget target) {
     return TargetJumpHandler(builder, target);
   }
+
+  void generateBreak(SourceInformation sourceInformation,
+      [LabelDefinition? label]);
+  void generateContinue(SourceInformation sourceInformation,
+      [LabelDefinition? label]);
+  void forEachBreak(void action(HBreak instruction, LocalsHandler locals));
+  void forEachContinue(
+      void action(HContinue instruction, LocalsHandler locals));
+  bool hasAnyContinue();
+  bool hasAnyBreak();
+  void close();
+  JumpTarget? get target;
+  List<LabelDefinition> get labels;
 }
 
 /// Jump handler used to avoid null checks when a target isn't used as the
@@ -39,14 +50,14 @@ class NullJumpHandler implements JumpHandler {
 
   @override
   void generateBreak(SourceInformation sourceInformation,
-      [LabelDefinition label]) {
+      [LabelDefinition? label]) {
     reporter.internalError(CURRENT_ELEMENT_SPANNABLE,
         'NullJumpHandler.generateBreak should not be called.');
   }
 
   @override
   void generateContinue(SourceInformation sourceInformation,
-      [LabelDefinition label]) {
+      [LabelDefinition? label]) {
     reporter.internalError(CURRENT_ELEMENT_SPANNABLE,
         'NullJumpHandler.generateContinue should not be called.');
   }
@@ -65,7 +76,7 @@ class NullJumpHandler implements JumpHandler {
   @override
   List<LabelDefinition> get labels => const [];
   @override
-  JumpTarget get target => null;
+  JumpTarget? get target => null;
 }
 
 /// Jump handler that records breaks until a target block is available.
@@ -88,7 +99,7 @@ class TargetJumpHandler implements JumpHandler {
 
   @override
   void generateBreak(SourceInformation sourceInformation,
-      [LabelDefinition label]) {
+      [LabelDefinition? label]) {
     HInstruction breakInstruction;
     if (label == null) {
       breakInstruction =
@@ -98,13 +109,13 @@ class TargetJumpHandler implements JumpHandler {
           HBreak.toLabel(_abstractValueDomain, label, sourceInformation);
     }
     LocalsHandler locals = LocalsHandler.from(builder.localsHandler);
-    builder.close(breakInstruction);
+    builder.close(breakInstruction as HJump);
     jumps.add(_JumpHandlerEntry(breakInstruction, locals));
   }
 
   @override
   void generateContinue(SourceInformation sourceInformation,
-      [LabelDefinition label]) {
+      [LabelDefinition? label]) {
     HInstruction continueInstruction;
     if (label == null) {
       continueInstruction =
@@ -117,23 +128,25 @@ class TargetJumpHandler implements JumpHandler {
       assert(!label.target.isSwitchCase);
     }
     LocalsHandler locals = LocalsHandler.from(builder.localsHandler);
-    builder.close(continueInstruction);
+    builder.close(continueInstruction as HJump);
     jumps.add(_JumpHandlerEntry(continueInstruction, locals));
   }
 
   @override
   void forEachBreak(
       void Function(HBreak instruction, LocalsHandler locals) action) {
     for (_JumpHandlerEntry entry in jumps) {
-      if (entry.isBreak()) action(entry.jumpInstruction, entry.locals);
+      final jumpInstruction = entry.jumpInstruction;
+      if (jumpInstruction is HBreak) action(jumpInstruction, entry.locals);
     }
   }
 
   @override
   void forEachContinue(
       void Function(HContinue instruction, LocalsHandler locals) action) {
     for (_JumpHandlerEntry entry in jumps) {
-      if (entry.isContinue()) action(entry.jumpInstruction, entry.locals);
+      final jumpInstruction = entry.jumpInstruction;
+      if (jumpInstruction is HContinue) action(jumpInstruction, entry.locals);
     }
   }
 
@@ -161,7 +174,7 @@ class TargetJumpHandler implements JumpHandler {
 
   @override
   List<LabelDefinition> get labels {
-    List<LabelDefinition> result = null;
+    List<LabelDefinition>? result;
     for (LabelDefinition element in target.labels) {
       result ??= <LabelDefinition>[];
       result.add(element);
@@ -177,13 +190,11 @@ abstract class SwitchCaseJumpHandler extends TargetJumpHandler {
   /// switch case loop.
   final Map<JumpTarget, int> targetIndexMap = {};
 
-  SwitchCaseJumpHandler(
-      interfaces.KernelSsaGraphBuilder builder, JumpTarget target)
-      : super(builder, target);
+  SwitchCaseJumpHandler(super.builder, super.target);
 
   @override
   void generateBreak(SourceInformation sourceInformation,
-      [LabelDefinition label]) {
+      [LabelDefinition? label]) {
     if (label == null) {
       // Creates a special break instruction for the synthetic loop generated
       // for a switch statement with continue statements. See
@@ -193,35 +204,34 @@ abstract class SwitchCaseJumpHandler extends TargetJumpHandler {
           _abstractValueDomain, target, sourceInformation,
           breakSwitchContinueLoop: true);
       LocalsHandler locals = LocalsHandler.from(builder.localsHandler);
-      builder.close(breakInstruction);
+      builder.close(breakInstruction as HJump);
       jumps.add(_JumpHandlerEntry(breakInstruction, locals));
     } else {
       super.generateBreak(sourceInformation, label);
     }
   }
 
-  bool isContinueToSwitchCase(LabelDefinition label) {
+  bool isContinueToSwitchCase(LabelDefinition? label) {
     return label != null && targetIndexMap.containsKey(label.target);
   }
 
   @override
   void generateContinue(SourceInformation sourceInformation,
-      [LabelDefinition label]) {
+      [LabelDefinition? label]) {
     if (isContinueToSwitchCase(label)) {
       // Creates the special instructions 'label = i; continue l;' used in
       // switch statements with continue statements. See
       // [SsaFromAstMixin.buildComplexSwitchStatement] for detail.
 
-      assert(label != null);
       HInstruction value = builder.graph
-          .addConstantInt(targetIndexMap[label.target], builder.closedWorld);
+          .addConstantInt(targetIndexMap[label!.target]!, builder.closedWorld);
       builder.localsHandler.updateLocal(target, value);
 
       assert(label.target.labels.contains(label));
       HInstruction continueInstruction =
           HContinue(_abstractValueDomain, target, sourceInformation);
       LocalsHandler locals = LocalsHandler.from(builder.localsHandler);
-      builder.close(continueInstruction);
+      builder.close(continueInstruction as HJump);
       jumps.add(_JumpHandlerEntry(continueInstruction, locals));
     } else {
       super.generateContinue(sourceInformation, label);

pkg/compiler/lib/src/ssa/locals_handler.dart

@@ -24,7 +24,7 @@ import 'types.dart';
 /// Keeps track of locals (including parameters and phis) when building. The
 /// 'this' reference is treated as parameter and hence handled by this class,
 /// too.
-class LocalsHandler implements interfaces.LocalsHandler {
+class LocalsHandler {
   /// The values of locals that can be directly accessed (without redirections
   /// to boxes or closure-fields).
   ///
@@ -83,7 +83,6 @@ class LocalsHandler implements interfaces.LocalsHandler {
 
   /// Substituted type variables occurring in [type] into the context of
   /// [contextClass].
-  @override
   DartType substInContext(DartType type) {
     DartType newType = type;
     final iType = instanceType;
@@ -341,7 +340,6 @@ class LocalsHandler implements interfaces.LocalsHandler {
   /// Returns an [HInstruction] for the given element. If the element is
   /// boxed or stored in a closure then the method generates code to retrieve
   /// the value.
-  @override
   HInstruction readLocal(Local local, {SourceInformation? sourceInformation}) {
     if (isAccessedDirectly(local)) {
       HInstruction? value = directLocals[local];
@@ -401,7 +399,6 @@ class LocalsHandler implements interfaces.LocalsHandler {
     }
   }
 
-  @override
   HInstruction readThis({SourceInformation? sourceInformation}) {
     return readLocal(_scopeInfo!.thisLocal!,
         sourceInformation: sourceInformation);
@@ -426,14 +423,12 @@ class LocalsHandler implements interfaces.LocalsHandler {
     });
   }
 
-  @override
   Local getTypeVariableAsLocal(TypeVariableType type) {
     return typeVariableLocals[type.element] ??= TypeVariableLocal(type.element);
   }
 
   /// Sets the [element] to [value]. If the element is boxed or stored in a
   /// closure then the method generates code to set the value.
-  @override
   void updateLocal(Local local, HInstruction value,
       {SourceInformation? sourceInformation}) {
     if (value is HRef) {

pkg/compiler/lib/src/ssa/loop_handler.dart

@@ -12,7 +12,6 @@ import '../inferrer/abstract_value_domain.dart';
 import '../io/source_information.dart';
 
 import 'builder.dart';
-import 'builder_interfaces.dart' as interfaces;
 import 'jump_handler.dart';
 import 'locals_handler.dart';
 import 'nodes.dart';
@@ -102,8 +101,8 @@ abstract class LoopHandler {
       HBasicBlock updateBlock = builder.addNewBlock();
 
       List<LocalsHandler> continueHandlers = <LocalsHandler>[];
-      jumpHandler.forEachContinue(
-          (HContinue instruction, interfaces.LocalsHandler locals) {
+      jumpHandler
+          .forEachContinue((HContinue instruction, LocalsHandler locals) {
         instruction.block.addSuccessor(updateBlock);
         continueHandlers.add(locals);
       });
@@ -262,8 +261,7 @@ abstract class LoopHandler {
 
     List<LocalsHandler> breakHandlers = <LocalsHandler>[];
     // Collect data for the successors and the phis at each break.
-    jumpHandler.forEachBreak(
-        (HBreak breakInstruction, interfaces.LocalsHandler locals) {
+    jumpHandler.forEachBreak((HBreak breakInstruction, LocalsHandler locals) {
       breakInstruction.block.addSuccessor(loopExitBlock);
       breakHandlers.add(locals);
     });