Count closures using the feedback vector cell map, specialize if count==1.

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 <memory>
 #include <sstream>
 
@@ skipping 576 matching lines @@
     if (FLAG_turbo_loop_peeling) {
       info()->MarkAsLoopPeelingEnabled();
     }
   }
   if (info()->is_optimizing_from_bytecode() ||
       !info()->shared_info()->asm_function()) {
     info()->MarkAsDeoptimizationEnabled();
     if (FLAG_inline_accessors) {
       info()->MarkAsAccessorInliningEnabled();
     }
+    if (info()->closure()->feedback_vector_cell()->map() ==
+        isolate()->heap()->one_closure_cell_map()) {
+      info()->MarkAsFunctionContextSpecializing();
+    }
   }
   if (!info()->is_optimizing_from_bytecode()) {
     if (!Compiler::EnsureDeoptimizationSupport(info())) return FAILED;
   } else if (FLAG_turbo_inlining) {
     info()->MarkAsInliningEnabled();
   }
 
   linkage_ = new (info()->zone())
       Linkage(Linkage::ComputeIncoming(info()->zone(), info()));
 
@@ skipping 1408 matching lines @@
   data->DeleteRegisterAllocationZone();
 }
 
 CompilationInfo* PipelineImpl::info() const { return data_->info(); }
 
 Isolate* PipelineImpl::isolate() const { return info()->isolate(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8