[debugger] simplify debug stepping.

src/x64/macro-assembler-x64.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.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 4320 matching lines @@
     }
     bind(&invoke);
   }
 }
 
 
 void MacroAssembler::FloodFunctionIfStepping(Register fun, Register new_target,
                                              const ParameterCount& expected,
                                              const ParameterCount& actual) {
   Label skip_flooding;
-  ExternalReference step_in_enabled =
-      ExternalReference::debug_step_in_enabled_address(isolate());
-  Operand step_in_enabled_operand = ExternalOperand(step_in_enabled);
-  cmpb(step_in_enabled_operand, Immediate(0));
-  j(equal, &skip_flooding);
+  ExternalReference last_step_action =
+      ExternalReference::debug_last_step_action_address(isolate());
+  Operand last_step_action_operand = ExternalOperand(last_step_action);
+  STATIC_ASSERT(StepFrame > StepIn);
+  cmpb(last_step_action_operand, Immediate(StepIn));
+  j(less, &skip_flooding);
   {
     FrameScope frame(this,
                      has_frame() ? StackFrame::NONE : StackFrame::INTERNAL);
     if (expected.is_reg()) {
       Integer32ToSmi(expected.reg(), expected.reg());
       Push(expected.reg());
     }
     if (actual.is_reg()) {
       Integer32ToSmi(actual.reg(), actual.reg());
       Push(actual.reg());
@@ skipping 1365 matching lines @@
   movl(rax, dividend);
   shrl(rax, Immediate(31));
   addl(rdx, rax);
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64