Fix bug with load elimination in checked mode.

runtime/vm/flow_graph_optimizer.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 4302 matching lines @@
         (representation_ == other->representation_) &&
         (instance_ == other->instance_) &&
         SameField(other);
   }
 
   // Create a zone allocated copy of this place.
   static Place* Wrap(const Place& place);
 
  private:
   static Definition* OriginalDefinition(Definition* defn) {
-    while (defn->IsRedefinition()) {
-      defn = defn->AsRedefinition()->value()->definition();
+    while (defn->IsRedefinition() || defn->IsAssertAssignable()) {
+      if (defn->IsRedefinition()) {
+        defn = defn->AsRedefinition()->value()->definition();
+      } else {
+        defn = defn->AsAssertAssignable()->value()->definition();
+      }
     }
     return defn;
   }
 
   bool SameField(Place* other) const {
     return (kind_ == kField) ? (field().raw() == other->field().raw())
                              : (offset_in_bytes_ == other->offset_in_bytes_);
   }
 
   intptr_t FieldHashcode() const {
@@ skipping 197 matching lines @@
   static bool CanBeAliased(AllocateObjectInstr* alloc) {
     if (alloc->identity() == AllocateObjectInstr::kUnknown) {
       bool escapes = false;
       for (Value* use = alloc->input_use_list();
            use != NULL;
            use = use->next_use()) {
         Instruction* instr = use->instruction();
         if (instr->IsPushArgument() ||
             (instr->IsStoreVMField() && (use->use_index() != 1)) ||
             (instr->IsStoreInstanceField() && (use->use_index() != 0)) ||
-            (instr->IsStoreStaticField()) ||
-            (instr->IsPhi())) {
+            instr->IsStoreStaticField() ||
+            instr->IsPhi() ||
+            instr->IsAssertAssignable() ||
+            instr->IsRedefinition()) {
           escapes = true;
           break;
         }
       }
 
       alloc->set_identity(escapes ? AllocateObjectInstr::kAliased
                                   : AllocateObjectInstr::kNotAliased);
     }
 
     return alloc->identity() != AllocateObjectInstr::kNotAliased;
@@ skipping 3204 matching lines @@
   }
 
   // Insert materializations at environment uses.
   for (intptr_t i = 0; i < exits.length(); i++) {
     CreateMaterializationAt(exits[i], alloc, alloc->cls(), *fields);
   }
 }
 
 
 }  // namespace dart