Improve redundant load elimination

runtime/vm/intermediate_language.cc

 // 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.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 849 matching lines @@
     for (intptr_t i = 0; i < var_count; i++) {
       phis_->Add(NULL);
     }
   }
   ASSERT((*phis_)[var_index] == NULL);
   (*phis_)[var_index] = new PhiInstr(this, PredecessorCount());
   phi_count_++;
 }
 
 
+void JoinEntryInstr::InsertPhi(PhiInstr* phi) {
+  // Lazily initialize the array of phis.
+  if (phis_ == NULL) {
+    phis_ = new ZoneGrowableArray<PhiInstr*>(1);
+  }
+  phis_->Add(phi);
+  phi_count_++;
+}
+
+
 void JoinEntryInstr::RemoveDeadPhis() {
   if (phis_ == NULL) return;
 
   for (intptr_t i = 0; i < phis_->length(); i++) {
     PhiInstr* phi = (*phis_)[i];
     if ((phi != NULL) && !phi->is_alive()) {
       (*phis_)[i] = NULL;
       phi_count_--;
     }
   }
@@ skipping 1873 matching lines @@
     default:
       UNREACHABLE();
       return -1;
   }
 }
 
 
 #undef __
 
 }  // namespace dart