Scale the OSR optimization threshold by loop nesting depth.

runtime/vm/code_generator.cc

 // Copyright (c) 2013, 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/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/bigint_operations.h"
 #include "vm/code_patcher.h"
@@ skipping 1300 matching lines @@
 
   if (FLAG_use_osr && (interrupt_bits == 0)) {
     DartFrameIterator iterator;
     StackFrame* frame = iterator.NextFrame();
     const Function& function = Function::Handle(frame->LookupDartFunction());
     ASSERT(!function.IsNull());
     if (!CanOptimizeFunction(function, isolate)) return;
     intptr_t osr_id =
         Code::Handle(function.unoptimized_code()).GetDeoptIdForOsr(frame->pc());
     if (FLAG_trace_osr) {
-      OS::Print("Attempting OSR for %s at id=%"Pd"\n",
+      OS::Print("Attempting OSR for %s at id=%"Pd", count=%"Pd"\n",
                 function.ToFullyQualifiedCString(),
-                osr_id);
+                osr_id,
+                function.usage_counter());
     }
 
     const Code& original_code = Code::Handle(function.CurrentCode());
     const Error& error =
         Error::Handle(Compiler::CompileOptimizedFunction(function, osr_id));
     if (!error.IsNull()) Exceptions::PropagateError(error);
 
     const Code& optimized_code = Code::Handle(function.CurrentCode());
     // The current code will not be changed in the case that the compiler
     // bailed out during OSR compilation.
@@ skipping 471 matching lines @@
 //   Arg1: Value that is being stored.
 DEFINE_RUNTIME_ENTRY(UpdateFieldCid, 2) {
   ASSERT(arguments.ArgCount() == kUpdateFieldCidRuntimeEntry.argument_count());
   const Field& field = Field::CheckedHandle(arguments.ArgAt(0));
   const Object& value = Object::Handle(arguments.ArgAt(1));
 
   field.UpdateCid(value.GetClassId());
 }
 
 }  // namespace dart