dart2js: Redo known-type analysis after load-elimination

pkg/compiler/lib/src/ssa/optimize.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.
 
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart' show Selectors;
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart' show Compiler;
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
@@ skipping 70 matching lines @@
         // interceptors are often in the way of LICM'able instructions.
         new SsaDeadCodeEliminator(closedWorld, this),
         new SsaGlobalValueNumberer(),
         // After GVN, some instructions might need their type to be
         // updated because they now have different inputs.
         new SsaTypePropagator(compiler, closedWorld),
         codeMotion = new SsaCodeMotion(),
         new SsaLoadElimination(compiler, closedWorld),
         new SsaRedundantPhiEliminator(),
         new SsaDeadPhiEliminator(),
+        // After GVN and load elimination the same value may be used in code
+        // controlled by a test on the value, so redo 'conversion insertion' to
+        // learn from the refined type.
+        new SsaTypeConversionInserter(closedWorld),
         new SsaTypePropagator(compiler, closedWorld),
         new SsaValueRangeAnalyzer(backend.helpers, closedWorld, this),
         // Previous optimizations may have generated new
         // opportunities for instruction simplification.
         new SsaInstructionSimplifier(backend, closedWorld, this, registry),
         new SsaCheckInserter(
             trustPrimitives, backend, closedWorld, boundsChecked),
       ];
       phases.forEach(runPhase);
 
@@ skipping 2659 matching lines @@
 
     keyedValues.forEach((receiver, values) {
       result.keyedValues[receiver] =
           new Map<HInstruction, HInstruction>.from(values);
     });
 
     result.nonEscapingReceivers.addAll(nonEscapingReceivers);
     return result;
   }
 }