[debugger] simplify debug stepping.

src/mips64/builtins-mips64.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_MIPS64
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 687 matching lines @@
   // Store resume mode into generator object.
   __ sd(a2, FieldMemOperand(a1, JSGeneratorObject::kResumeModeOffset));
 
   // Load suspended function and context.
   __ ld(cp, FieldMemOperand(a1, JSGeneratorObject::kContextOffset));
   __ ld(a4, FieldMemOperand(a1, JSGeneratorObject::kFunctionOffset));
 
   // Flood function if we are stepping.
   Label prepare_step_in_if_stepping, prepare_step_in_suspended_generator;
   Label stepping_prepared;
-  ExternalReference step_in_enabled =
-      ExternalReference::debug_step_in_enabled_address(masm->isolate());
-  __ li(a5, Operand(step_in_enabled));
+  ExternalReference last_step_action =
+      ExternalReference::debug_last_step_action_address(masm->isolate());
+  STATIC_ASSERT(StepFrame > StepIn);
+  __ li(a5, Operand(last_step_action));
   __ lb(a5, MemOperand(a5));
-  __ Branch(&prepare_step_in_if_stepping, ne, a5, Operand(zero_reg));
+  __ Branch(&prepare_step_in_if_stepping, ge, a5, Operand(StepIn));
 
   // Flood function if we need to continue stepping in the suspended generator.
   ExternalReference debug_suspended_generator =
       ExternalReference::debug_suspended_generator_address(masm->isolate());
   __ li(a5, Operand(debug_suspended_generator));
   __ ld(a5, MemOperand(a5));
   __ Branch(&prepare_step_in_suspended_generator, eq, a1, Operand(a5));
   __ bind(&stepping_prepared);
 
   // Push receiver.
@@ skipping 2222 matching lines @@
   }
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64