Rename ClosureVariable, use separate IR forms for declaration and assignment.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.dart

 // Copyright (c) 2014, 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.
 
 library tree_ir_builder;
 
 import '../dart2jslib.dart' as dart2js;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
@@ skipping 31 matching lines @@
  * Otherwise, the output of Builder looks very much like the input.  In
  * particular, intermediate values and blocks used for local control flow are
  * still all named.
  */
 class Builder extends cps_ir.Visitor<Node> {
   final dart2js.InternalErrorFunction internalError;
 
   /// Maps variable/parameter elements to the Tree variables that represent it.
   final Map<Local, List<Variable>> local2variables = <Local, List<Variable>>{};
 
-  /// Like [local2variables], except for closure variables.
-  final Map<cps_ir.ClosureVariable, Variable> local2closure =
-      <cps_ir.ClosureVariable, Variable>{};
+  /// Like [local2variables], except for mutable variables.
+  final Map<cps_ir.MutableVariable, Variable> local2mutable =

[karlklose, 2015/02/03 09:56:16]

I would really like to get rid of this naming convention.

[Kevin Millikin (Google), 2015/02/03 14:11:49]

Concrete suggestions for naming maps?  Name them after the type of values?

+      <cps_ir.MutableVariable, Variable>{};
 
   // Continuations with more than one use are replaced with Tree labels.  This
   // is the mapping from continuations to labels.
   final Map<cps_ir.Continuation, Label> labels = <cps_ir.Continuation, Label>{};
 
   ExecutableElement currentElement;
   cps_ir.Continuation returnContinuation;
 
   Builder parent;
 
   Builder(this.internalError, [this.parent]);
 
   Builder createInnerBuilder() {
     return new Builder(internalError, this);
   }
 
   /// Variable used in [buildPhiAssignments] as a temporary when swapping
   /// variables.
   Variable phiTempVar;
 
-  Variable getClosureVariable(cps_ir.ClosureVariable irVariable) {
+  Variable addMutableVariable(cps_ir.MutableVariable irVariable) {
     if (irVariable.host != currentElement) {
-      return parent.getClosureVariable(irVariable);
+      return parent.addMutableVariable(irVariable);
     }
-    return local2closure.putIfAbsent(irVariable,
-        () => new Variable(currentElement, irVariable.hint));
+    assert(!local2mutable.containsKey(irVariable));
+    Variable variable = new Variable(currentElement, irVariable.hint);
+    local2mutable[irVariable] = variable;
+    return variable;
+  }
+
+  Variable getMutableVariableReference(
+        cps_ir.Reference<cps_ir.MutableVariable> reference) {
+    if (reference.definition.host != currentElement) {
+      return parent.getMutableVariableReference(reference);
+    }
+    return local2mutable[reference.definition];
   }
 
   /// Obtains the variable representing the given primitive. Returns null for
   /// primitives that have no reference and do not need a variable.
   Variable getVariable(cps_ir.Primitive primitive) {
     if (primitive.registerIndex == null) {
       return null; // variable is unused
     }
     List<Variable> variables = local2variables.putIfAbsent(primitive.hint,
         () => <Variable>[]);
@@ skipping 39 matching lines @@
       currentElement = node.element;
       returnContinuation = node.body.returnContinuation;
 
       phiTempVar = new Variable(node.element, null);
 
       body = visit(node.body);
     }
     return new FieldDefinition(node.element, body);
   }
 
-  Variable getFunctionParameter(cps_ir.Definition variable) {
+  Variable addFunctionParameter(cps_ir.Definition variable) {
     if (variable is cps_ir.Parameter) {
       return getVariable(variable);
     } else {
-      return getClosureVariable(variable as cps_ir.ClosureVariable);
+      return addMutableVariable(variable as cps_ir.MutableVariable);
     }
   }
 
   FunctionDefinition buildFunction(cps_ir.FunctionDefinition node) {
     currentElement = node.element;
     List<Variable> parameters = <Variable>[];
     for (cps_ir.Definition p in node.parameters) {
-      Variable parameter = getFunctionParameter(p);
+      Variable parameter = addFunctionParameter(p);
       assert(parameter != null);
       ++parameter.writeCount; // Being a parameter counts as a write.
       parameters.add(parameter);
     }
 
     Statement body;
     if (!node.isAbstract) {
       returnContinuation = node.body.returnContinuation;
       phiTempVar = new Variable(node.element, null);
       body = visit(node.body);
     }
 
     return new FunctionDefinition(node.element, parameters,
         body, node.localConstants, node.defaultParameterValues);
   }
 
   ConstructorDefinition buildConstructor(cps_ir.ConstructorDefinition node) {
     currentElement = node.element;
     List<Variable> parameters = <Variable>[];
     for (cps_ir.Definition p in node.parameters) {
-      Variable parameter = getFunctionParameter(p);
+      Variable parameter = addFunctionParameter(p);
       assert(parameter != null);
       ++parameter.writeCount; // Being a parameter counts as a write.
       parameters.add(parameter);
     }
     List<Initializer> initializers;
     Statement body;
     if (!node.isAbstract) {
       initializers = node.initializers.map(visit).toList();
       returnContinuation = node.body.returnContinuation;
 
@@ skipping 240 matching lines @@
       return new Return(expression);
     } else {
       assert(cont.parameters.length == 1);
       Function nextBuilder = cont.hasExactlyOneUse ?
           () => visit(cont.body) : () => new Break(labels[cont]);
       return buildContinuationAssignment(cont.parameters.single, expression,
           nextBuilder);
     }
   }
 
-  Expression visitGetClosureVariable(cps_ir.GetClosureVariable node) {
-    return getClosureVariable(node.variable.definition);
+  Statement visitLetMutable(cps_ir.LetMutable node) {
+    Variable variable = addMutableVariable(node.variable);
+    Expression value = getVariableReference(node.value);
+    return new Assign(variable, value, visit(node.body), isDeclaration: true);
   }
 
-  Statement visitSetClosureVariable(cps_ir.SetClosureVariable node) {
-    Variable variable = getClosureVariable(node.variable.definition);
+  Expression visitGetMutableVariable(cps_ir.GetMutableVariable node) {
+    return getMutableVariableReference(node.variable);
+  }
+
+  Statement visitSetMutableVariable(cps_ir.SetMutableVariable node) {
+    Variable variable = getMutableVariableReference(node.variable);
     Expression value = getVariableReference(node.value);
-    return new Assign(variable, value, visit(node.body),
-                      isDeclaration: node.isDeclaration);
+    return new Assign(variable, value, visit(node.body));
   }
 
   Statement visitDeclareFunction(cps_ir.DeclareFunction node) {
-    Variable variable = getClosureVariable(node.variable.definition);
+    Variable variable = addMutableVariable(node.variable);
     FunctionDefinition function = makeSubFunction(node.definition);
     return new FunctionDeclaration(variable, function, visit(node.body));
   }
 
   Statement visitTypeOperator(cps_ir.TypeOperator node) {
     Expression receiver = getVariableReference(node.receiver);
     Expression concat =
         new TypeOperator(receiver, node.type, isTypeTest: node.isTypeTest);
     return continueWithExpression(node.continuation, concat);
   }
@@ skipping 115 matching lines @@
     // visited.
     internalError(CURRENT_ELEMENT_SPANNABLE, 'Unexpected IR node: $node.');
     return null;
   }
 
   Expression visitIsTrue(cps_ir.IsTrue node) {
     return getVariableReference(node.value);
   }
 }