RFC: Start refactoring to provide more than a single backend.

lib/compiler/implementation/ssa/codegen.dart

 // Copyright (c) 2012, 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.
 
 class SsaCodeGeneratorTask extends CompilerTask {
-  SsaCodeGeneratorTask(Compiler compiler) : super(compiler);
+  final JavaScriptBackend backend;
+  SsaCodeGeneratorTask(JavaScriptBackend backend)
+      : this.backend = backend,
+        super(backend.compiler);
   String get name() => 'SSA code generator';
+  NativeEmitter get nativeEmitter() => backend.emitter.nativeEmitter;
 
 
   String buildJavaScriptFunction(FunctionElement element,
                                  String parameters,
                                  String body) {
     String extraSpace = "";
     // Members are emitted inside a JavaScript object literal. To line up the
     // indentation we want the closing curly brace to be indented by one space.
     // Example:
     // defineClass("A", "B", ... , {
@@ skipping 12 matching lines @@
     }
     return 'function($parameters) {\n$body$extraSpace}';
   }
 
   String generateMethod(WorkItem work, HGraph graph) {
     return measure(() {
       compiler.tracer.traceGraph("codegen", graph);
       Map<Element, String> parameterNames = getParameterNames(work);
       String parameters = Strings.join(parameterNames.getValues(), ', ');
       SsaOptimizedCodeGenerator codegen = new SsaOptimizedCodeGenerator(
-          compiler, work, parameters, parameterNames);
+          backend, work, parameters, parameterNames);
       codegen.visitGraph(graph);
 
       FunctionElement element = work.element;
       String code;
       if (element.isInstanceMember()
           && element.enclosingElement.isClass()
           && element.enclosingElement.isNative()
-          && native.isOverriddenMethod(element,
-                                       element.enclosingElement,
-                                       compiler.emitter.nativeEmitter)) {
+          && native.isOverriddenMethod(
+              element, element.enclosingElement, nativeEmitter)) {
         // Record that this method is overridden. In case of optional
         // arguments, the emitter will generate stubs to handle them,
         // and needs to know if the method is overridden.
-        compiler.emitter.nativeEmitter.overriddenMethods.add(element);
+        nativeEmitter.overriddenMethods.add(element);
         StringBuffer buffer = new StringBuffer();
         native.generateMethodWithPrototypeCheckForElement(
             compiler, buffer, element, '${codegen.buffer}', parameters);
         code = buffer.toString();
       } else {
         code = codegen.buffer.toString();
       }
       return buildJavaScriptFunction(element, parameters, code);
     });
   }
 
   String generateBailoutMethod(WorkItem work, HGraph graph) {
     return measure(() {
       compiler.tracer.traceGraph("codegen-bailout", graph);
       new SsaBailoutPropagator(compiler).visitGraph(graph);
 
       Map<Element, String> parameterNames = getParameterNames(work);
       String parameters = Strings.join(parameterNames.getValues(), ', ');
       SsaUnoptimizedCodeGenerator codegen = new SsaUnoptimizedCodeGenerator(
-          compiler, work, parameters, parameterNames);
+          backend, work, parameters, parameterNames);
       codegen.visitGraph(graph);
 
       StringBuffer newParameters = new StringBuffer();
       if (!parameterNames.isEmpty()) newParameters.add('$parameters, ');
       newParameters.add('state');
 
       for (int i = 0; i < codegen.maxBailoutParameters; i++) {
         newParameters.add(', env$i');
       }
 
@@ skipping 45 matching lines @@
    * expression, and that it only generates expressions of the form
    *   variable = expression
    * which are also valid as parts of a "var" declaration.
    */
   static final int TYPE_STATEMENT = 0;
   static final int TYPE_EXPRESSION = 1;
   static final int TYPE_DECLARATION = 2;
 
   static final String TEMPORARY_PREFIX = 't';
 
-  final Compiler compiler;
+  final JavaScriptBackend backend;
   final WorkItem work;
   final StringBuffer buffer;
   final String parameters;
 
   final Map<Element, String> parameterNames;
   final Map<int, String> names;
   final Set<String> usedNames;
   final Set<HInstruction> declaredInstructions;
   final Map<String, int> prefixes;
   final Set<HInstruction> generateAtUseSite;
@@ skipping 21 matching lines @@
   HBasicBlock currentBlock;
 
   // Records a block-information that is being handled specially.
   // Used to break bad recursion.
   HBlockInformation currentBlockInformation;
   // The subgraph is used to delimit traversal for some constructions, e.g.,
   // if branches.
   SubGraph subGraph;
 
   LibraryElement get currentLibrary() => work.element.getLibrary();
+  Compiler get compiler() => backend.compiler;
 
   bool isGenerateAtUseSite(HInstruction instruction) {
     return generateAtUseSite.contains(instruction);
   }
 
-  SsaCodeGenerator(this.compiler,
+  SsaCodeGenerator(this.backend,
                    this.work,
                    this.parameters,
                    this.parameterNames)
     : names = new Map<int, String>(),
       prefixes = new Map<String, int>(),
       usedNames = new Set<String>(),
       declaredInstructions = new Set<HInstruction>(),
       buffer = new StringBuffer(),
       generateAtUseSite = new Set<HInstruction>(),
       logicalOperations = new Map<HPhi, String>(),
       breakAction = new Map<Element, ElementAction>(),
       continueAction = new Map<Element, ElementAction>(),
       phiEquivalence = new Equivalence<HPhi>(),
       unsignedShiftPrecedences = JSPrecedence.binary['>>>'] {
 
     for (final name in parameterNames.getValues()) {
       prefixes[name] = 0;
     }
 
     // Create a namespace for temporaries.
     prefixes[TEMPORARY_PREFIX] = 0;
 
-    Interceptors interceptors = compiler.builder.interceptors;
+    Interceptors interceptors = backend.builder.interceptors;
     equalsNullElement = interceptors.getEqualsNullInterceptor();
     boolifiedEqualsNullElement =
         interceptors.getBoolifiedVersionOf(equalsNullElement);
   }
 
   abstract visitTypeGuard(HTypeGuard node);
 
   abstract beginGraph(HGraph graph);
   abstract endGraph(HGraph graph);
 
@@ skipping 1815 matching lines @@
     beginExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
     checkObject(input, '===');
     buffer.add(" && ");
     checkType(input, element);
     endExpression(JSPrecedence.LOGICAL_AND_PRECEDENCE);
     endExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
   }
 
   void checkType(HInstruction input, Element element) {
     bool requiresNativeIsCheck =
-        compiler.emitter.nativeEmitter.requiresNativeIsCheck(element);
+        compiler.backend.emitter.nativeEmitter.requiresNativeIsCheck(element);
     if (!requiresNativeIsCheck) buffer.add('!!');
     use(input, JSPrecedence.MEMBER_PRECEDENCE);
     buffer.add('.');
     buffer.add(compiler.namer.operatorIs(element));
     if (requiresNativeIsCheck) buffer.add('()');
   }
 
   void handleStringSupertypeCheck(HInstruction input, Element element) {
     // Make sure List and String don't share supertypes, otherwise we
     // would need to check for List too.
@@ skipping 98 matching lines @@
       endExpression(JSPrecedence.LOGICAL_OR_PRECEDENCE);
     }
   }
 
   void visitTypeConversion(HTypeConversion node) {
     if (node.checked) {
       Element element = node.type.computeType(compiler).element;
       compiler.registerIsCheck(element);
       SourceString helper;
       String additionalArgument;
-      bool nativeCheck =
-          compiler.emitter.nativeEmitter.requiresNativeIsCheck(element);
+      bool nativeCheck = nativeEmitter.requiresNativeIsCheck(element);
       beginExpression(JSPrecedence.CALL_PRECEDENCE);
 
       if (element == compiler.stringClass) {
         helper = const SourceString('stringTypeCheck');
       } else if (element == compiler.doubleClass) {
         helper = const SourceString('doubleTypeCheck');
       } else if (element == compiler.numClass) {
         helper = const SourceString('numTypeCheck');
       } else if (element == compiler.boolClass) {
         helper = const SourceString('boolTypeCheck');
@@ skipping 31 matching lines @@
       if (additionalArgument !== null) buffer.add(", '$additionalArgument'");
       buffer.add(')');
       endExpression(JSPrecedence.CALL_PRECEDENCE);
     } else {
       use(node.checkedInput, expectedPrecedence);
     }
   }
 }
 
 class SsaOptimizedCodeGenerator extends SsaCodeGenerator {
-  SsaOptimizedCodeGenerator(compiler, work, parameters, parameterNames)
-    : super(compiler, work, parameters, parameterNames);
+  SsaOptimizedCodeGenerator(backend, work, parameters, parameterNames)
+    : super(backend, work, parameters, parameterNames);
 
   void beginGraph(HGraph graph) {}
   void endGraph(HGraph graph) {}
 
   void bailout(HTypeGuard guard, String reason) {
     HInstruction input = guard.guarded;
     Namer namer = compiler.namer;
     Element element = work.element;
     buffer.add('return ');
     if (element.isInstanceMember()) {
@@ skipping 147 matching lines @@
   }
 }
 
 class SsaUnoptimizedCodeGenerator extends SsaCodeGenerator {
 
   final StringBuffer setup;
   final List<String> labels;
   int labelId = 0;
   int maxBailoutParameters = 0;
 
-  SsaUnoptimizedCodeGenerator(compiler, work, parameters, parameterNames)
-    : super(compiler, work, parameters, parameterNames),
+  SsaUnoptimizedCodeGenerator(backend, work, parameters, parameterNames)
+    : super(backend, work, parameters, parameterNames),
       setup = new StringBuffer(),
       labels = <String>[];
 
   String pushLabel() {
     String label = 'L${labelId++}';
     labels.addLast(label);
     return label;
   }
 
   String popLabel() {
@@ skipping 211 matching lines @@
       startBailoutSwitch();
     }
   }
 
   void endLabeledBlock(HLabeledBlockInformation labeledBlockInfo) {
     if (labeledBlockInfo.body.start.hasGuards()) {
       endBailoutSwitch();
     }
   }
 }