[debugger] simplify debug stepping.

src/ppc/builtins-ppc.cc

 // Copyright 2014 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_PPC
 
 #include "src/codegen.h"
 #include "src/debug/debug.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 704 matching lines @@
   // Store resume mode into generator object.
   __ StoreP(r5, FieldMemOperand(r4, JSGeneratorObject::kResumeModeOffset), r0);
 
   // Load suspended function and context.
   __ LoadP(cp, FieldMemOperand(r4, JSGeneratorObject::kContextOffset));
   __ LoadP(r7, FieldMemOperand(r4, 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());
-  __ mov(ip, Operand(step_in_enabled));
+  ExternalReference last_step_action =
+      ExternalReference::debug_last_step_action_address(masm->isolate());
+  STATIC_ASSERT(StepFrame > StepIn);
+  __ mov(ip, Operand(last_step_action));
   __ lbz(ip, MemOperand(ip));
   __ cmpi(ip, Operand::Zero());
-  __ bne(&prepare_step_in_if_stepping);
+  __ bge(&prepare_step_in_if_stepping);
 
   // Flood function if we need to continue stepping in the suspended generator.
 
   ExternalReference debug_suspended_generator =
       ExternalReference::debug_suspended_generator_address(masm->isolate());
 
   __ mov(ip, Operand(debug_suspended_generator));
   __ LoadP(ip, MemOperand(ip));
   __ cmp(ip, r4);
   __ beq(&prepare_step_in_suspended_generator);
@@ skipping 2194 matching lines @@
     __ bkpt(0);
   }
 }
 
 
 #undef __
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_PPC