[turbofan] Add single --turbo flag.

src/v8.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/assembler.h"
 #include "src/base/once.h"
 #include "src/base/platform/platform.h"
 #include "src/bootstrapper.h"
@@ skipping 59 matching lines @@
     // Avoid random seeds in predictable mode.
     FLAG_random_seed = 12347;
   }
 
   if (FLAG_stress_compaction) {
     FLAG_force_marking_deque_overflows = true;
     FLAG_gc_global = true;
     FLAG_max_semi_space_size = 1;
   }
 
+  if (FLAG_turbo && strcmp(FLAG_turbo_filter, "~~") == 0) {
+    const char* filter_flag = "--turbo-filter=*";
+    FlagList::SetFlagsFromString(filter_flag, StrLength(filter_flag));
+  }
+
   base::OS::Initialize(FLAG_random_seed, FLAG_hard_abort, FLAG_gc_fake_mmap);
 
   Isolate::InitializeOncePerProcess();
 
   Sampler::SetUp();
   CpuFeatures::Probe(false);
   init_memcopy_functions();
   // The custom exp implementation needs 16KB of lookup data; initialize it
   // on demand.
   init_fast_sqrt_function();
@@ skipping 42 matching lines @@
 
 
 void V8::SetSnapshotBlob(StartupData* snapshot_blob) {
 #ifdef V8_USE_EXTERNAL_STARTUP_DATA
   base::CallOnce(&init_snapshot_once, &SetSnapshotFromFile, snapshot_blob);
 #else
   CHECK(false);
 #endif
 }
 } }  // namespace v8::internal