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 213 matching lines @@
 
     ElementAst parse(AstElement element) {
       if (!compiler.irBuilder.hasIr(element)) {
         return new ElementAst(element);
       } else {
         cps_ir.FunctionDefinition function = compiler.irBuilder.getIr(element);
         // Transformations on the CPS IR.
         new RedundantPhiEliminator().rewrite(function);
         compiler.tracer.traceCompilation(element.name, null, compiler);
         compiler.tracer.traceGraph("Redundant phi elimination", function);
+        new ShrinkingReducer().rewrite(function);
+        compiler.tracer.traceGraph("Shrinking reductions", function);
         // Do not rewrite the IR after variable allocation.  Allocation
         // makes decisions based on an approximation of IR variable live
         // ranges that can be invalidated by transforming the IR.
         new cps_ir.RegisterAllocator().visit(function);
 
         tree_builder.Builder builder = new tree_builder.Builder(compiler);
         tree_ir.FunctionDefinition definition = builder.build(function);
         assert(definition != null);
         compiler.tracer.traceGraph('Tree builder', definition);
 
@@ skipping 428 matching lines @@
   }
 
   Constant compileMetadata(MetadataAnnotation metadata,
                            Node node,
                            TreeElements elements) {
     return measure(() {
       return constantCompiler.compileMetadata(metadata, node, elements);
     });
   }
 }