Remove special meaning when usage counter reaches the threshold.

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2012, 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/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/assembler_macros.h"
 #include "vm/compiler.h"
@@ skipping 1516 matching lines @@
 void StubCode::GenerateUsageCounterIncrement(Assembler* assembler,
                                              Register ic_reg,
                                              Register temp_reg) {
   __ movq(temp_reg, FieldAddress(ic_reg, ICData::function_offset()));
   Label is_hot;
   if (FlowGraphCompiler::CanOptimize()) {
     ASSERT(FLAG_optimization_counter_threshold > 1);
     // The usage_counter is always less than FLAG_optimization_counter_threshold
     // except when the function gets optimized.
     __ cmpq(FieldAddress(temp_reg, Function::usage_counter_offset()),
-        Immediate(FLAG_optimization_counter_threshold - 1));
-    // Do not increment to equality with threshold, since a counter greater
-    // than threshold denotes a function that was already optimized.
-    // The equality should be reached only at exit of the method
-    // (return instruction).
+        Immediate(FLAG_optimization_counter_threshold));
     __ j(EQUAL, &is_hot, Assembler::kNearJump);
     // As long as VM has no OSR do not optimize in the middle of the function
     // but only at exit so that we have collected all type feedback before
     // optimizing.
   }
   __ incq(FieldAddress(temp_reg, Function::usage_counter_offset()));
   __ Bind(&is_hot);
 }
 
 // Generate inline cache check for 'num_args'.
@@ skipping 477 matching lines @@
   __ CallRuntime(kUpdateICDataTwoArgsRuntimeEntry);
   __ Drop(4);
   __ LeaveFrame();
 
   __ jmp(&compute_result, Assembler::kNearJump);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64