Fix issue 20190: Mark Uint32/Int32 typed data load to produce a Mint always

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/cpu.h"
 #include "vm/dart_entry.h"
@@ skipping 5505 matching lines @@
               current->GetDeoptId(),
               current->GetBlock()->block_id(),
               pre_header->block_id());
   }
   // Move the instruction out of the loop.
   current->RemoveEnvironment();
   it->RemoveCurrentFromGraph();
   GotoInstr* last = pre_header->last_instruction()->AsGoto();
   // Using kind kEffect will not assign a fresh ssa temporary index.
   flow_graph()->InsertBefore(last, current, last->env(), FlowGraph::kEffect);
-  current->deopt_id_ = last->GetDeoptId();
+  if (current->CanDeoptimize()) {
+    // Do not change characteristic of a non-deoptimizing instruction.
+    current->deopt_id_ = last->GetDeoptId();

[Vyacheslav Egorov (Google), 2014/07/25 08:38:43]

Question: what if instruction can't deoptimize by itself but can potentially
serve as a deoptimization target? (e.g. binary operations that require argument
unboxing).

In this case we also need to update deopt_id_ otherwise if we later insert
convertion it might deoptimize  to the wrong place.

+  }
 }
 
 
 void LICM::TryHoistCheckSmiThroughPhi(ForwardInstructionIterator* it,
                                       BlockEntryInstr* header,
                                       BlockEntryInstr* pre_header,
                                       CheckSmiInstr* current) {
   PhiInstr* phi = current->value()->definition()->AsPhi();
   if (!header->loop_info()->Contains(phi->block()->preorder_number())) {
     return;
@@ skipping 4880 matching lines @@
 
   // Insert materializations at environment uses.
   for (intptr_t i = 0; i < exits_collector_.exits().length(); i++) {
     CreateMaterializationAt(
         exits_collector_.exits()[i], alloc, alloc->cls(), *slots);
   }
 }
 
 
 }  // namespace dart