Extend sminess propagator to process branch instructions.

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 1651 matching lines @@
 
   for (ForwardInstructionIterator it(block); !it.Done(); it.Advance()) {
     Instruction* instr = it.Current();
     if (instr->IsCheckSmi()) {
       const intptr_t value_ssa_index =
           instr->InputAt(0)->definition()->ssa_temp_index();
       if (!known_smis_->Contains(value_ssa_index)) {
         known_smis_->Add(value_ssa_index);
         rollback_checks_.Add(value_ssa_index);
       }
+    } else if (instr->IsBranch()) {
+      for (intptr_t i = 0; i < instr->InputCount(); i++) {
+        Value* use = instr->InputAt(i);
+        if (known_smis_->Contains(use->definition()->ssa_temp_index())) {
+          use->set_reaching_cid(kSmiCid);
+        }
+      }
     }
   }
 
   for (intptr_t i = 0; i < block->dominated_blocks().length(); ++i) {
     PropagateSminessRecursive(block->dominated_blocks()[i]);
   }
 
   if (block->last_instruction()->SuccessorCount() == 1 &&
       block->last_instruction()->SuccessorAt(0)->IsJoinEntry()) {
     JoinEntryInstr* join =
@@ skipping 2233 matching lines @@
 
   if (FLAG_trace_constant_propagation) {
     OS::Print("\n==== After constant propagation ====\n");
     FlowGraphPrinter printer(*graph_);
     printer.PrintBlocks();
   }
 }
 
 
 }  // namespace dart