S390: [debugger] simplify debug stepping.

src/s390/macro-assembler-s390.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.
 
 #include <assert.h>  // For assert
 #include <limits.h>  // For LONG_MIN, LONG_MAX.
 
 #if V8_TARGET_ARCH_S390
 
 #include "src/base/bits.h"
@@ skipping 1291 matching lines @@
       Jump(adaptor, RelocInfo::CODE_TARGET);
     }
     bind(&regular_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());
-  mov(r6, Operand(step_in_enabled));
-  LoadlB(r6, MemOperand(r6));
-  CmpP(r6, Operand::Zero());
-  beq(&skip_flooding);
+  ExternalReference last_step_action =
+      ExternalReference::debug_last_step_action_address(isolate());
+  STATIC_ASSERT(StepFrame > StepIn);
+  mov(r6, Operand(last_step_action));
+  LoadB(r6, MemOperand(r6));
+  CmpP(r6, Operand(StepIn));
+  blt(&skip_flooding);
   {
     FrameScope frame(this,
                      has_frame() ? StackFrame::NONE : StackFrame::INTERNAL);
     if (expected.is_reg()) {
       SmiTag(expected.reg());
       Push(expected.reg());
     }
     if (actual.is_reg()) {
       SmiTag(actual.reg());
       Push(actual.reg());
@@ skipping 4195 matching lines @@
   }
   if (mag.shift > 0) ShiftRightArith(result, result, Operand(mag.shift));
   ExtractBit(r0, dividend, 31);
   AddP(result, r0);
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_S390