Prevent excessive deoptimization when optimistically assuming Smi in typed data stores.

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/compiler.h"
 #include "vm/cpu.h"
@@ skipping 1426 matching lines @@
       return InlineSetIndexed(kind, target, call, receiver, token_pos,
                               value_check, entry, last);
     case MethodRecognizer::kInt8ArraySetIndexed:
     case MethodRecognizer::kUint8ArraySetIndexed:
     case MethodRecognizer::kUint8ClampedArraySetIndexed:
     case MethodRecognizer::kExternalUint8ArraySetIndexed:
     case MethodRecognizer::kExternalUint8ClampedArraySetIndexed:
     case MethodRecognizer::kInt16ArraySetIndexed:
     case MethodRecognizer::kUint16ArraySetIndexed:
       // Optimistically assume Smi.
-      // TODO(srdjan): Check deopt reason to prevent repeated deoptimizations.
+      if (ic_data.HasDeoptReason(ICData::kDeoptCheckSmi)) {
+        // Optimistic assumption failed at least once.
+        return false;
+      }
       value_check = ic_data.AsUnaryClassChecksForCid(kSmiCid, target);
       return InlineSetIndexed(kind, target, call, receiver, token_pos,
                               value_check, entry, last);
     case MethodRecognizer::kInt32ArraySetIndexed:
     case MethodRecognizer::kUint32ArraySetIndexed: {
       // Value check not needed for Int32 and Uint32 arrays because they
       // implicitly contain unboxing instructions which check for right type.
       ICData& value_check = ICData::Handle();
       return InlineSetIndexed(kind, target, call, receiver, token_pos,
                               value_check, entry, last);
@@ skipping 7206 matching lines @@
 
   // Insert materializations at environment uses.
   for (intptr_t i = 0; i < exits_collector_.exits().length(); i++) {
     CreateMaterializationAt(
         exits_collector_.exits()[i], alloc, *slots);
   }
 }
 
 
 }  // namespace dart