Implement control reducer, which reduces branches and phis together in a single fixpoint.

src/compiler/scheduler.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <deque>
 #include <queue>
 
 #include "src/compiler/scheduler.h"
 
 #include "src/compiler/graph.h"
@@ skipping 363 matching lines @@
     if (succ == NULL) {
       Trace("Connect #%d:%s, B%d -> end\n", node->id(), node->op()->mnemonic(),
             block->id().ToInt());
     } else {
       Trace("Connect #%d:%s, B%d -> B%d\n", node->id(), node->op()->mnemonic(),
             block->id().ToInt(), succ->id().ToInt());
     }
   }
 
   bool IsFinalMerge(Node* node) {
-    return (node == scheduler_->graph_->end()->InputAt(0));
+    return (node->opcode() == IrOpcode::kMerge &&
+            node == scheduler_->graph_->end()->InputAt(0));
   }
 };
 
 
 void Scheduler::BuildCFG() {
   Trace("--- CREATING CFG -------------------------------------------\n");
   CFGBuilder cfg_builder(zone_, this);
   cfg_builder.Run();
   // Initialize per-block data.
   scheduled_nodes_.resize(schedule_->BasicBlockCount(), NodeVector(zone_));
@@ skipping 855 matching lines @@
 #if DEBUG
   if (FLAG_trace_turbo_scheduler) PrintRPO(num_loops, loops, final_order);
   VerifySpecialRPO(num_loops, loops, final_order);
 #endif
   return final_order;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8