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

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
===================================================================
--- runtime/vm/flow_graph_optimizer.cc	(revision 38558)
+++ runtime/vm/flow_graph_optimizer.cc	(working copy)
@@ -5523,7 +5523,10 @@
   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.

+  }
 }