[turbofan] Use heavy-handed graph duplication to do loop peeling for OSR.

src/compiler/pipeline.cc

 // Copyright 2014 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 "src/compiler/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/platform/elapsed-timer.h"
@@ skipping 737 matching lines @@
 
     {  // Print JSON.
       FILE* json_file = OpenVisualizerLogFile(info, NULL, "json", "a+");
       if (json_file == nullptr) return;
       OFStream json_of(json_file);
       json_of << "{\"name\":\"" << phase << "\",\"type\":\"graph\",\"data\":"
               << AsJSON(*graph, data->source_positions()) << "},\n";
       fclose(json_file);
     }
 
-    OFStream os(stdout);
     if (FLAG_trace_turbo_graph) {  // Simple textual RPO.
+      OFStream os(stdout);
       os << "-- Graph after " << phase << " -- " << std::endl;
       os << AsRPO(*graph);
     }
   }
 };
 
 
 struct VerifyGraphPhase {
   static const char* phase_name() { return nullptr; }
 
@@ skipping 400 matching lines @@
 
   if (FLAG_trace_turbo && !data->MayHaveUnverifiableGraph()) {
     TurboCfgFile tcf(data->isolate());
     tcf << AsC1VAllocator("CodeGen", data->register_allocator());
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8