Implement shrinking reductions in CPS IR

sdk/lib/_internal/compiler/implementation/dart_backend/backend.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.
 
 part of dart_backend;
 
 // TODO(ahe): This class is simply wrong.  This backend should use
 // elements when it can, not AST nodes.  Perhaps a [Map<Element,
 // TreeElements>] is what is needed.
 class ElementAst {
@@ skipping 215 matching lines @@
 
     final elementAsts = new Map<Element, ElementAst>();
 
     ElementAst parse(AstElement element) {
       if (!compiler.irBuilder.hasIr(element)) {
         return new ElementAst(element);
       } else {
         cps_ir.FunctionDefinition function = compiler.irBuilder.getIr(element);
         new RedundantPhiEliminator().rewrite(function);
         compiler.tracer.traceGraph("Redundant phi elimination", function);
+        new ShrinkingReducer().rewrite(function);
+        compiler.tracer.traceGraph("Shrinking reductions", function);
         tree_builder.Builder builder = new tree_builder.Builder(compiler);
         tree_ir.FunctionDefinition definition = builder.build(function);
         assert(definition != null);
         compiler.tracer.traceCompilation(element.name, null, compiler);
         compiler.tracer.traceGraph('Tree builder', definition);
         TreeElementMapping treeElements = new TreeElementMapping(element);
         new StatementRewriter().rewrite(definition);
         compiler.tracer.traceGraph('Statement rewriter', definition);
         new CopyPropagator().rewrite(definition);
         compiler.tracer.traceGraph('Copy propagation', definition);
@@ skipping 421 matching lines @@
   }
 
   Constant compileMetadata(MetadataAnnotation metadata,
                            Node node,
                            TreeElements elements) {
     return measure(() {
       return constantCompiler.compileMetadata(metadata, node, elements);
     });
   }
 }