Fix a bug with store-to-load forwarding for typed arrays.

runtime/vm/flow_graph_optimizer.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/flow_graph_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 3221 matching lines @@
         if (IsInterferingStore(instr, &offset_in_words)) {
           // Interfering stores kill only loads from the same offset.
           if ((offset_in_words < kill_by_offset_.length()) &&
               (kill_by_offset_[offset_in_words] != NULL)) {
             kill->AddAll(kill_by_offset_[offset_in_words]);
             // There is no need to clear out_values when clearing GEN set
             // because only those values that are in the GEN set
             // will ever be used.
             gen->RemoveAll(kill_by_offset_[offset_in_words]);
 
-            Definition* load = map_->Lookup(instr->AsDefinition());
-            if (load != NULL) {
-              // Store has a corresponding numbered load. Try forwarding
-              // stored value to it.
-              gen->Add(load->expr_id());
-              if (out_values == NULL) out_values = CreateBlockOutValues();
-              (*out_values)[load->expr_id()] = GetStoredValue(instr);
+            // Only forward stores to normal arrays and float64 arrays
+            // to loads because other array stores (intXX/uintXX/float32)
+            // may implicitly convert the value stored.
+            StoreIndexedInstr* array_store = instr->AsStoreIndexed();
+            if (array_store == NULL ||
+                array_store->class_id() == kArrayCid ||
+                array_store->class_id() == kFloat64ArrayCid) {
+              Definition* load = map_->Lookup(instr->AsDefinition());
+              if (load != NULL) {
+                // Store has a corresponding numbered load. Try forwarding
+                // stored value to it.
+                gen->Add(load->expr_id());
+                if (out_values == NULL) out_values = CreateBlockOutValues();
+                (*out_values)[load->expr_id()] = GetStoredValue(instr);
+              }
             }
           }
           ASSERT(instr->IsDefinition() &&
                  !IsLoadEliminationCandidate(instr->AsDefinition()));
           continue;
         }
 
         // Other instructions with side effects kill all loads.
         if (instr->HasSideEffect()) {
           kill->SetAll();
@@ skipping 1252 matching lines @@
 
   if (FLAG_trace_constant_propagation) {
     OS::Print("\n==== After constant propagation ====\n");
     FlowGraphPrinter printer(*graph_);
     printer.PrintBlocks();
   }
 }
 
 
 }  // namespace dart