kernel->ssa: get simple constructors working

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

 // Copyright (c) 2016, 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 'package:kernel/ast.dart' as ir;
 
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart';
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart';
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../io/source_information.dart';
 import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../kernel/kernel.dart';
 import '../resolution/tree_elements.dart';
 import '../tree/dartstring.dart';
+import '../tree/nodes.dart' show FunctionExpression, Node;
 import '../types/masks.dart';
 import '../universe/selector.dart';
 import 'graph_builder.dart';
 import 'kernel_ast_adapter.dart';
 import 'kernel_string_builder.dart';
 import 'locals_handler.dart';
 import 'loop_handler.dart';
 import 'nodes.dart';
 import 'ssa_branch_builder.dart';
 
@@ skipping 91 matching lines @@
 
   @override
   HInstruction popBoolified() {
     HInstruction value = pop();
     // TODO(het): add boolean conversion type check
     HInstruction result = new HBoolify(value, backend.boolType);
     add(result);
     return result;
   }
 
+  /// Generative constructors are built in several stages.

[Siggi Cherem (dart-lang), 2016/11/14 18:22:25]

dartdoc nit: Consider making the first comment a description of the function
below, rather than a description of the algorithm?

/// Builds generative constructors.
///
/// Generative constructors are ...


another minor nit: "several" => "two"?

[Harry Terkelsen, 2016/11/14 23:23:40]

oops :) when I started that comment I thought there would be more phases

+  ///
+  /// First, the field values for every instance field for every class in the
+  /// class hierarchy are collected. Then, create a function body that sets
+  /// all of the instance fields to the collected values and call the
+  /// constructor bodies for all constructors in the hierarchy.
   void buildConstructor(ir.Constructor constructor) {
-    // TODO(het): Actually handle this correctly
-    HBasicBlock block = graph.addNewBlock();
-    open(graph.entry);
-    close(new HGoto()).addSuccessor(block);
-    open(block);
-    closeAndGotoExit(new HGoto());
-    graph.finalize();
+    openFunction();
+
+    // Collect field values for the current class.
+    // TODO(het): Does kernel always put field initializers in the constructor

[Siggi Cherem (dart-lang), 2016/11/14 18:22:25]

good question for tomorrow :)?

[Harry Terkelsen, 2016/11/14 23:23:40]

Acknowledged.

+    //            initializer list? If so then this is unnecessary...
+    Map<ir.Field, HInstruction> fieldValues =
+        _collectFieldValues(constructor.enclosingClass);
+
+    _buildInitializers(constructor, fieldValues);
+
+    final constructorArguments = <HInstruction>[];
+    astAdapter.getClass(constructor.enclosingClass).forEachInstanceField(
+        (ClassElement enclosingClass, FieldElement member) {
+      var value = fieldValues[astAdapter.getFieldFromNode(member)];
+      constructorArguments.add(value);
+    }, includeSuperAndInjectedMembers: true);
+
+    // TODO(het): If the class needs runtime type information, add it as a
+    // constructor argument.
+    HInstruction create = new HCreate(
+        astAdapter.getClass(constructor.enclosingClass),
+        constructorArguments,
+        new TypeMask.nonNullExact(
+            astAdapter.getClass(constructor.enclosingClass),
+            compiler.closedWorld),
+        instantiatedTypes: <DartType>[
+          astAdapter.getClass(constructor.enclosingClass).thisType
+        ],
+        hasRtiInput: false);

[Siggi Cherem (dart-lang), 2016/11/14 18:22:25]

just checking - this might change when addressing the TODO above?

[Harry Terkelsen, 2016/11/14 23:23:40]

yes

+
+    add(create);
+
+    // Generate calls to the constructor bodies.
+
+    closeAndGotoExit(new HReturn(create, null));
+    closeFunction();
+  }
+
+  /// Maps the fields of a class to their SSA values.
+  Map<ir.Field, HInstruction> _collectFieldValues(ir.Class clazz) {
+    final fieldValues = <ir.Field, HInstruction>{};
+
+    for (var field in clazz.fields) {
+      if (field.initializer == null) {
+        fieldValues[field] = graph.addConstantNull(compiler);
+      } else {
+        field.initializer.accept(this);
+        fieldValues[field] = pop();
+      }
+    }
+
+    return fieldValues;
+  }
+
+  /// Collects field initializers all the way up the inheritance chain.
+  void _buildInitializers(
+      ir.Constructor constructor, Map<ir.Field, HInstruction> fieldValues) {
+    var foundSuperCall = false;
+    for (var initializer in constructor.initializers) {
+      if (initializer is ir.SuperInitializer) {
+        foundSuperCall = true;
+        var superConstructor = initializer.target;
+        var arguments = _normalizeAndBuildArguments(
+            superConstructor.function, initializer.arguments);
+        _buildSuperConstructor(superConstructor, arguments, fieldValues);
+      } else if (initializer is ir.FieldInitializer) {
+        initializer.value.accept(this);
+        fieldValues[initializer.field] = pop();
+      }
+    }
+
+    // If there was no super-call initializer, then call the default constructor
+    // in the superclass.
+    if (!foundSuperCall) {

[Siggi Cherem (dart-lang), 2016/11/14 18:22:25]

I wonder if kernel injects this call always at the end in that case? Or if we
can consider making this normalization happen in kernel (TODO?)

[Harry Terkelsen, 2016/11/14 23:23:40]

Done.

+      if (constructor.enclosingClass != astAdapter.objectClass) {
+        var superclass = constructor.enclosingClass.superclass;
+        var defaultConstructor = superclass.constructors
+            .firstWhere((c) => c.name == '', orElse: () => null);
+        if (defaultConstructor == null) {
+          compiler.reporter.internalError(
+              NO_LOCATION_SPANNABLE, 'Could not find default constructor.');
+        }
+        _buildSuperConstructor(
+            defaultConstructor, <HInstruction>[], fieldValues);
+      }
+    }
+  }
+
+  List<HInstruction> _normalizeAndBuildArguments(
+      ir.FunctionNode function, ir.Arguments arguments) {
+    var signature = astAdapter.getFunctionSignature(function);
+    var builtArguments = <HInstruction>[];
+    var positionalIndex = 0;
+    signature.forEachRequiredParameter((_) {
+      arguments.positional[positionalIndex++].accept(this);
+      builtArguments.add(pop());
+    });
+    if (!signature.optionalParametersAreNamed) {
+      signature.forEachOptionalParameter((ParameterElement element) {
+        if (positionalIndex < arguments.positional.length) {
+          arguments.positional[positionalIndex++].accept(this);
+          builtArguments.add(pop());
+        } else {
+          var constantValue =
+              backend.constants.getConstantValue(element.constant);
+          assert(invariant(element, constantValue != null,
+              message: 'No constant computed for $element'));
+          builtArguments.add(graph.addConstant(constantValue, compiler));
+        }
+      });
+    } else {
+      signature.orderedOptionalParameters.forEach((ParameterElement element) {
+        var correspondingNamed = arguments.named.firstWhere(
+            (named) => named.name == element.name,
+            orElse: () => null);
+        if (correspondingNamed != null) {
+          correspondingNamed.value.accept(this);
+          builtArguments.add(pop());
+        } else {
+          var constantValue =
+              backend.constants.getConstantValue(element.constant);
+          assert(invariant(element, constantValue != null,
+              message: 'No constant computed for $element'));
+          builtArguments.add(graph.addConstant(constantValue, compiler));
+        }
+      });
+    }
+
+    return builtArguments;
+  }
+
+  /// Builds the given super [constructor] by collecting it's field values and
+  /// building it's initializers. We build super constructors all the way up
+  /// to the [Object] constructor.
+  void _buildSuperConstructor(ir.Constructor constructor,

[Siggi Cherem (dart-lang), 2016/11/14 18:22:25]

Consider renaming this to avoid giving the impression that we are creating the
actual super constructor function?

Some ideas:
 - _buildInlinedSuperConstructor
 - _buildInlinedSuperInitializers (in case we only intend to put initializer
code and nothing from the constructor bodies)

[Harry Terkelsen, 2016/11/14 23:23:40]

Done.

+      List<HInstruction> arguments, Map<ir.Field, HInstruction> fieldValues) {
+    // TODO(het): Handle RTI if class needs it
+    fieldValues.addAll(_collectFieldValues(constructor.enclosingClass));
+
+    var signature = astAdapter.getFunctionSignature(constructor.function);
+    var index = 0;
+    signature.orderedForEachParameter((ParameterElement parameter) {
+      HInstruction argument = arguments[index++];
+      // Because we are inlining the initializer, we must update
+      // what was given as parameter. This will be used in case
+      // there is a parameter check expression in the initializer.
+      parameters[parameter] = argument;
+      localsHandler.updateLocal(parameter, argument);
+    });
+
+    // TODO(het): set the locals handler state as if we were inlining the
+    // constructor.
+    _buildInitializers(constructor, fieldValues);
   }
 
   /// Builds a SSA graph for [procedure].
   void buildProcedure(ir.Procedure procedure) {
     openFunction();
     procedure.function.body.accept(this);
     closeFunction();
   }
 
   void openFunction() {
     HBasicBlock block = graph.addNewBlock();
     open(graph.entry);
-    localsHandler.startFunction(targetElement, resolvedAst.node);
+
+    Node function;
+    if (resolvedAst.kind == ResolvedAstKind.PARSED) {
+      function = resolvedAst.node;
+    }
+    localsHandler.startFunction(targetElement, function);
     close(new HGoto()).addSuccessor(block);
 
     open(block);
   }
 
   void closeFunction() {
     if (!isAborted()) closeAndGotoExit(new HGoto());
     graph.finalize();
   }
 
@@ skipping 656 matching lines @@
     push(new HNot(popBoolified(), backend.boolType));
   }
 
   @override
   void visitStringConcatenation(ir.StringConcatenation stringConcat) {
     KernelStringBuilder stringBuilder = new KernelStringBuilder(this);
     stringConcat.accept(stringBuilder);
     stack.add(stringBuilder.result);
   }
 }