Initial implementation of on-stack replacement (OSR).

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index 21ed7c90f79ade1fb2b3d6fdbc42e80f02b056c8..9c96af95fe8c01bf7a62a642afc231610dcf3ab3 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -1418,18 +1418,7 @@ void StubCode::GenerateOptimizedUsageCounterIncrement(Assembler* assembler) {
     __ popq(func_reg);     // Restore.
     __ LeaveFrame();
   }
-  Label is_hot;
-  if (FlowGraphCompiler::CanOptimize()) {
-    ASSERT(FLAG_optimization_counter_threshold > 1);
-    __ cmpq(FieldAddress(func_reg, Function::usage_counter_offset()),
-        Immediate(FLAG_optimization_counter_threshold));
-    __ j(GREATER_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(func_reg, Function::usage_counter_offset()));
-  __ Bind(&is_hot);
 }
 
 
@@ -1440,22 +1429,10 @@ void StubCode::GenerateUsageCounterIncrement(Assembler* assembler,
   Register func_reg = temp_reg;
   ASSERT(ic_reg != func_reg);
   __ movq(func_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(func_reg, Function::usage_counter_offset()),
-        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(func_reg, Function::usage_counter_offset()));
-  __ Bind(&is_hot);
 }
 
+
 // Generate inline cache check for 'num_args'.
 //  RBX: Inline cache data object.
 //  R10: Arguments descriptor array.