Break typecheck dependency in escape analysis.

src/hydrogen-escape-analysis.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 194 matching lines @@
           HCheckHeapObject* check = HCheckHeapObject::cast(instr);
           if (check->value() != allocate) continue;
           check->DeleteAndReplaceWith(NULL);
           break;
         }
         case HValue::kCheckMaps: {
           HCheckMaps* mapcheck = HCheckMaps::cast(instr);
           if (mapcheck->value() != allocate) continue;
           // TODO(mstarzinger): This approach breaks if the tracked map value
           // is not a HConstant. Find a repro test case and fix this.
+          for (HUseIterator it(mapcheck->uses()); !it.Done(); it.Advance()) {
+            if (!it.value()->IsLoadNamedField()) continue;
+            HLoadNamedField* load = HLoadNamedField::cast(it.value());
+            ASSERT(load->typecheck() == mapcheck);
+            load->clear_typecheck();
+          }
           ASSERT(mapcheck->HasNoUses());
+
           mapcheck->DeleteAndReplaceWith(NULL);
           break;
         }
         default:
           // Nothing to see here, move along ...
           break;
       }
     }
 
     // Propagate the block state forward to all successor blocks.
@@ skipping 54 matching lines @@
     AnalyzeDataFlow(allocate);
 
     cumulative_values_ += number_of_values_;
     ASSERT(allocate->HasNoUses());
     ASSERT(!allocate->IsLinked());
   }
 }
 
 
 } }  // namespace v8::internal