[debugger] remove step count parameter from prepare step.

And tons of changes to debugger tests.

R=bmeurer@chromium.org
BUG=chromium:569835
LOG=N

Review URL: https://codereview.chromium.org/1525173003

Cr-Commit-Position: refs/heads/master@{#32885}

src/debug/debug.js

@@ -943,11 +943,14 @@ function ExecutionState(break_id) {
   this.selected_frame = 0;
 }
 
-ExecutionState.prototype.prepareStep = function(opt_action, opt_count) {
-  var action = Debug.StepAction.StepIn;
-  if (!IS_UNDEFINED(opt_action)) action = TO_NUMBER(opt_action);
-  var count = opt_count ? TO_NUMBER(opt_count) : 1;
-  return %PrepareStep(this.break_id, action, count);
+ExecutionState.prototype.prepareStep = function(action) {
+  if (action === Debug.StepAction.StepIn ||
+      action === Debug.StepAction.StepOut ||
+      action === Debug.StepAction.StepNext ||
+      action === Debug.StepAction.StepFrame) {
+    return %PrepareStep(this.break_id, action);
+  }
+  throw MakeTypeError(kDebuggerType);
 };
 
 ExecutionState.prototype.evaluateGlobal = function(source, disable_break,
@@ -1451,21 +1454,10 @@ DebugCommandProcessor.prototype.processDebugJSONRequest = function(
 DebugCommandProcessor.prototype.continueRequest_ = function(request, response) {
   // Check for arguments for continue.
   if (request.arguments) {
-    var count = 1;
     var action = Debug.StepAction.StepIn;
 
     // Pull out arguments.
     var stepaction = request.arguments.stepaction;
-    var stepcount = request.arguments.stepcount;
-
-    // Get the stepcount argument if any.
-    if (stepcount) {
-      count = TO_NUMBER(stepcount);
-      if (count < 0) {
-        throw MakeError(kDebugger,
-                        'Invalid stepcount argument "' + stepcount + '".');
-      }
-    }
 
     // Get the stepaction argument.
     if (stepaction) {
@@ -1482,7 +1474,7 @@ DebugCommandProcessor.prototype.continueRequest_ = function(request, response) {
     }
 
     // Set up the VM for stepping.
-    this.exec_state_.prepareStep(action, count);
+    this.exec_state_.prepareStep(action);
   }
 
   // VM should be running after executing this request.

src/runtime/runtime-debug.cc

@@ -1212,11 +1212,11 @@ RUNTIME_FUNCTION(Runtime_IsBreakOnException) {
 //          of frames to step down.
 RUNTIME_FUNCTION(Runtime_PrepareStep) {
   HandleScope scope(isolate);
-  DCHECK(args.length() == 3);
+  DCHECK(args.length() == 2);
   CONVERT_NUMBER_CHECKED(int, break_id, Int32, args[0]);
   RUNTIME_ASSERT(isolate->debug()->CheckExecutionState(break_id));
 
-  if (!args[1]->IsNumber() || !args[2]->IsNumber()) {
+  if (!args[1]->IsNumber()) {
     return isolate->Throw(isolate->heap()->illegal_argument_string());
   }
 
@@ -1227,18 +1227,11 @@ RUNTIME_FUNCTION(Runtime_PrepareStep) {
     return isolate->Throw(isolate->heap()->illegal_argument_string());
   }
 
-  // Get the number of steps.
-  int step_count = NumberToInt32(args[2]);
-  if (step_count < 1) {
-    return isolate->Throw(isolate->heap()->illegal_argument_string());
-  }
-
   // Clear all current stepping setup.
   isolate->debug()->ClearStepping();
 
   // Prepare step.
-  isolate->debug()->PrepareStep(static_cast<StepAction>(step_action),
-                                step_count);
+  isolate->debug()->PrepareStep(static_cast<StepAction>(step_action), 1);
   return isolate->heap()->undefined_value();
 }
 

src/runtime/runtime.h

@@ -183,7 +183,7 @@ namespace internal {
   F(ClearBreakPoint, 1, 1)                     \
   F(ChangeBreakOnException, 2, 1)              \
   F(IsBreakOnException, 1, 1)                  \
-  F(PrepareStep, 3, 1)                         \
+  F(PrepareStep, 2, 1)                         \
   F(ClearStepping, 0, 1)                       \
   F(DebugEvaluate, 6, 1)                       \
   F(DebugEvaluateGlobal, 4, 1)                 \

test/mjsunit/debug-allscopes-on-debugger.js

@@ -29,7 +29,7 @@ function listener(event, exec_state, event_data, data) {
       ++break_count;
 
       if (break_count !== expected_breaks) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+        exec_state.prepareStep(Debug.StepAction.StepIn);
         print("Next step prepared");
       }
     }

test/mjsunit/debug-break-native.js

@@ -10,7 +10,7 @@ var exception = null;
 function breakListener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
     // Assert that the break happens at an intended location.
     assertTrue(exec_state.frame(0).sourceLineText().indexOf("// break") > 0);
   } catch (e) {

test/mjsunit/debug-constructor.js

@@ -35,7 +35,7 @@ function listener(event, exec_state, event_data, data) {
   if (event == Debug.DebugEvent.Break)
   {
     call_graph += exec_state.frame().func().name();
-    exec_state.prepareStep();
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 };
 

test/mjsunit/debug-continue.js

@@ -74,12 +74,14 @@ function listener(event, exec_state, event_data, data) {
 
     // Test some illegal continue requests.
     testArguments(exec_state, '{"stepaction":"maybe"}', false);
-    testArguments(exec_state, '{"stepcount":-1}', false);
 
     // Test some legal continue requests.
     testArguments(exec_state, '{"stepaction":"in"}', true);
     testArguments(exec_state, '{"stepaction":"next"}', true);
     testArguments(exec_state, '{"stepaction":"out"}', true);
+
+    // Step count argument is ignored.
+    testArguments(exec_state, '{"stepcount":-1}', true);
     testArguments(exec_state, '{"stepcount":1}', true);
     testArguments(exec_state, '{"stepcount":10}', true);
     testArguments(exec_state, '{"stepcount":"10"}', true);

test/mjsunit/debug-liveedit-stepin.js

@@ -34,7 +34,7 @@ function listener(event, exec_state, event_data, data) {
           assertUnreachable();
       }
     }
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/debug-return-value.js

@@ -98,7 +98,7 @@ function listener(event, exec_state, event_data, data) {
           default:
             fail("Unexpected");
         }
-        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+        exec_state.prepareStep(Debug.StepAction.StepIn);
       } else {
         // Position at the end of the function.
         assertEquals(debugger_source_position + 50,

test/mjsunit/debug-step-4.js

@@ -53,9 +53,7 @@ function h() {
   }
 }
 
-function TestCase(step_count, expected_final_state) {
-  print("Test case, step count: " + step_count);
-
+function TestCase(expected_final_state) {
   var listener_exception = null;
   var state_snapshot;
   var listener_state;
@@ -68,7 +66,7 @@ function TestCase(step_count, expected_final_state) {
       if (event == Debug.DebugEvent.Break) {
         if (listener_state == 0) {
           Debug.clearBreakPoint(bp);
-          exec_state.prepareStep(Debug.StepAction.StepNext, step_count);
+          exec_state.prepareStep(Debug.StepAction.StepNext);
           listener_state = 1;
         } else if (listener_state == 1) {
           state_snapshot = String(state);
@@ -102,8 +100,4 @@ function TestCase(step_count, expected_final_state) {
 // Warm-up -- make sure all is compiled and ready for breakpoint.
 h();
 
-TestCase(0, "0,0,-1");
-TestCase(1, "0,0,-1");
-TestCase(2, "0,0,0");
-TestCase(5, "0,0,1");
-TestCase(8, "0,0,2");
+TestCase("0,0,-1");

test/mjsunit/debug-step-end-of-script.js

@@ -11,7 +11,7 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     assertEquals(expected.shift(), exec_state.frame(0).sourceLineText());
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   } catch (e) {
     %AbortJS(e + "\n" + e.stack);
   }

test/mjsunit/debug-step-into-json.js

@@ -13,8 +13,9 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     print(event_data.sourceLineText());
-    assertTrue(event_data.sourceLineText().indexOf(`Break ${break_count++}.`) > 0);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    assertTrue(
+        event_data.sourceLineText().indexOf(`Break ${break_count++}.`) > 0);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/debug-step-into-valueof.js

@@ -14,7 +14,7 @@ function listener(event, exec_state, event_data, data) {
   try {
     print(event_data.sourceLineText());
     assertTrue(event_data.sourceLineText().indexOf(`Break ${break_count++}.`) > 0);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/debug-step-turbofan.js

@@ -33,7 +33,7 @@ var break_count = 0;
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
     print(exec_state.frame(0).sourceLineText());
     var match = exec_state.frame(0).sourceLineText().match(/Break (\d)/);
     assertNotNull(match);

test/mjsunit/debug-step.js

@@ -37,10 +37,10 @@ var bp1, bp2;
 
 function listener(event, exec_state, event_data, data) {
   if (event == Debug.DebugEvent.Break) {
-    if (state == 0) {
-      exec_state.prepareStep(Debug.StepAction.StepIn, 1000);
-      state = 1;
-    } else if (state == 1) {
+    if (step_count > 0) {
+      exec_state.prepareStep(Debug.StepAction.StepIn);
+      step_count--;
+    } else {
       result = exec_state.frame().evaluate("i").value();
       // Clear the break point on line 2 if set.
       if (bp2) {
@@ -65,19 +65,8 @@ function f() {
 bp1 = Debug.setBreakPoint(f, 1);
 
 // Check that performing 1000 steps will make i 499.
-state = 0;
+var step_count = 1000;
 result = -1;
 f();
 assertEquals(332, result);
-
-// Check that performing 1000 steps with a break point on the statement in the
-// for loop (line 2) will only make i 0 as a real break point breaks even when
-// multiple steps have been requested.
-state = 0;
-result = -1;
-bp2 = Debug.setBreakPoint(f, 3);
-f();
-assertEquals(0, result);
-
-// Get rid of the debug event listener.
 Debug.setListener(null);

test/mjsunit/debug-stepframe-clearing.js

@@ -48,7 +48,7 @@ function listener(event, exec_state, event_data, data) {
     if (break_count >= 0 && break_count < 2) {
       // 0, 1: Keep stepping through frames.
       assertEquals(break_count, match_value);
-      exec_state.prepareStep(Debug.StepAction.StepFrame, 1);
+      exec_state.prepareStep(Debug.StepAction.StepFrame);
     } else if (break_count === 2) {
       // 2: let the code run to a breakpoint we set. The load should
       // go monomorphic.
@@ -58,7 +58,7 @@ function listener(event, exec_state, event_data, data) {
       // call still have the ability to break like before?
       assertEquals(break_count, match_value);
       Debug.clearBreakPoint(bp_f1_line7);
-      exec_state.prepareStep(Debug.StepAction.StepFrame, 1);
+      exec_state.prepareStep(Debug.StepAction.StepFrame);
     } else {
       assertEquals(4, break_count);
       assertEquals(2, match_value);

test/mjsunit/debug-stepframe.js

@@ -82,7 +82,6 @@ Object.defineProperty(o, "set", { set : set });
 Debug = debug.Debug;
 var break_count = 0
 var exception = null;
-var step_size;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
@@ -92,22 +91,20 @@ function listener(event, exec_state, event_data, data) {
     var match = line.match(/\/\/ Break (\d+)$/);
     assertEquals(2, match.length);
     assertEquals(break_count, parseInt(match[1]));
-    break_count += step_size;
-    exec_state.prepareStep(Debug.StepAction.StepFrame, step_size);
+    break_count ++;
+    exec_state.prepareStep(Debug.StepAction.StepFrame);
   } catch (e) {
     print(e + e.stack);
     exception = e;
   }
 }
 
-for (step_size = 1; step_size < 6; step_size++) {
-  print("step size = " + step_size);
-  break_count = 0;
-  Debug.setListener(listener);
-  debugger;                 // Break 0
-  f0();
-  Debug.setListener(null);  // Break 16
-  assertTrue(break_count > 14);
-}
+
+break_count = 0;
+Debug.setListener(listener);
+debugger;                 // Break 0
+f0();
+Debug.setListener(null);  // Break 16
+assertTrue(break_count > 14);
 
 assertNull(exception);

test/mjsunit/debug-stepin-accessor-ic.js

@@ -31,7 +31,7 @@ function listener(event, exec_state, event_data, data) {
   try {
     var source_line = exec_state.frame(0).sourceLineText();
     assertTrue(source_line.indexOf("// Break") > 0);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
     break_count++;
   } catch (e) {
     exception = e;

test/mjsunit/debug-stepin-accessor.js

@@ -41,14 +41,14 @@ var expected_function_name = null;
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 1) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
-        state = 2;
-      } else if (state == 2) {
+      if (state == 3) {
         assertEquals(expected_source_line_text,
                      event_data.sourceLineText());
         assertEquals(expected_function_name, event_data.func().name());
-        state = 3;
+        state = 4;
+      } else {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
       }
     }
   } catch(e) {
@@ -241,7 +241,7 @@ for (var n in this) {
   state = 1;
   this[n]();
   assertNull(exception);
-  assertEquals(3, state);
+  assertEquals(4, state);
 }
 
 // Get rid of the debug event listener.

test/mjsunit/debug-stepin-builtin-callback-opt.js

@@ -15,7 +15,7 @@ function listener(event, exec_state, event_data, data) {
     print(event_data.sourceLineText());
     assertTrue(
         event_data.sourceLineText().indexOf(`Break ${break_count++}.`) > 0);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/debug-stepin-builtin-callback.js

@@ -31,127 +31,114 @@
 
 Debug = debug.Debug
 
-var exception = false;
+var exception = null;
 
 function array_listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (breaks == 0) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
-        breaks = 1;
-      } else if (breaks <= 3) {
-        breaks++;
-        // Check whether we break at the expected line.
-        print(event_data.sourceLineText());
-        assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0);
-        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
-      }
+      print(event_data.sourceLineText(), breaks);
+      assertTrue(event_data.sourceLineText().indexOf(`B${breaks++}`) > 0);
+      exec_state.prepareStep(Debug.StepAction.StepIn);
     }
   } catch (e) {
-    exception = true;
+    print(e);
+    quit();
+    exception = e;
   }
 };
 
 function cb_false(num) {
-  print("element " + num);  // Expected to step to this point.
-  return false;
-}
+  print("element " + num);  // B2 B5 B8
+  return false;             // B3 B6 B9
+}                           // B4 B7 B10
 
 function cb_true(num) {
-  print("element " + num);  // Expected to step to this point.
-  return true;
-}
+  print("element " + num);  // B2 B5 B8
+  return true;              // B3 B6 B9
+}                           // B4 B7 B10
 
 function cb_reduce(a, b) {
-  print("elements " + a + " and " + b);  // Expected to step to this point.
-  return a + b;
-}
+  print("elements " + a + " and " + b);  // B2 B5
+  return a + b;                          // B3 B6
+}                                        // B4 B7
 
-var a = [1, 2, 3, 4];
-
-Debug.setListener(array_listener);
+var a = [1, 2, 3];
 
 var breaks = 0;
-debugger;
-a.forEach(cb_true);
-assertFalse(exception);
-assertEquals(4, breaks);
+Debug.setListener(array_listener);
+debugger;                 // B0
+a.forEach(cb_true);       // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 breaks = 0;
-debugger;
-a.some(cb_false);
-assertFalse(exception);
-assertEquals(4, breaks);
+Debug.setListener(array_listener);
+debugger;                 // B0
+a.some(cb_false);         // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 breaks = 0;
-debugger;
-a.every(cb_true);
-assertEquals(4, breaks);
-assertFalse(exception);
+Debug.setListener(array_listener);
+debugger;                 // B0
+a.every(cb_true);         // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 breaks = 0;
-debugger;
-a.map(cb_true);
-assertFalse(exception);
-assertEquals(4, breaks);
+Debug.setListener(array_listener);
+debugger;                 // B0
+a.map(cb_true);           // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 breaks = 0;
-debugger;
-a.filter(cb_true);
-assertFalse(exception);
-assertEquals(4, breaks);
+Debug.setListener(array_listener);
+debugger;                 // B0
+a.filter(cb_true);        // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 breaks = 0;
-debugger;
-a.reduce(cb_reduce);
-assertFalse(exception);
-assertEquals(4, breaks);
+Debug.setListener(array_listener);
+debugger;                 // B0
+a.reduce(cb_reduce);      // B1
+Debug.setListener(null);  // B8
+assertNull(exception);
+assertEquals(9, breaks);
 
 breaks = 0;
-debugger;
-a.reduceRight(cb_reduce);
-assertFalse(exception);
-assertEquals(4, breaks);
-
-Debug.setListener(null);
+Debug.setListener(array_listener);
+debugger;                  // B0
+a.reduceRight(cb_reduce);  // B1
+Debug.setListener(null);   // B8
+assertNull(exception);
+assertEquals(9, breaks);
 
 
 // Test two levels of builtin callbacks:
 // Array.forEach calls a callback function, which by itself uses
 // Array.forEach with another callback function.
 
-function second_level_listener(event, exec_state, event_data, data) {
-  try {
-    if (event == Debug.DebugEvent.Break) {
-      if (breaks == 0) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
-        breaks = 1;
-      } else if (breaks <= 16) {
-        breaks++;
-        // Check whether we break at the expected line.
-        assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0);
-        // Step two steps further every four breaks to skip the
-        // forEach call in the first level of recurision.
-        var step = (breaks % 4 == 1) ? 6 : 3;
-        exec_state.prepareStep(Debug.StepAction.StepIn, step);
-      }
-    }
-  } catch (e) {
-    exception = true;
-  }
-};
+function cb_true_2(num) {
+  print("element " + num);  // B3 B6 B9  B15 B18 B21 B27 B30 B33
+  return true;              // B4 B7 B10 B16 B19 B22 B28 B31 B34
+}                           // B5 B8 B11 B17 B20 B23 B29 B32 B35
 
 function cb_foreach(num) {
-  a.forEach(cb_true);
-  print("back to the first level of recursion.");
-}
-
-Debug.setListener(second_level_listener);
+  a.forEach(cb_true_2);     // B2  B14 B20 B26
+  print("back.");           // B12 B18 B24 B36
+}                           // B13 B19 B25 B37
 
 breaks = 0;
-debugger;
-a.forEach(cb_foreach);
-assertFalse(exception);
-assertEquals(17, breaks);
-
-Debug.setListener(null);
+Debug.setListener(array_listener);
+debugger;                   // B0
+a.forEach(cb_foreach);      // B1
+Debug.setListener(null);    // B38
+assertNull(exception);
+assertEquals(39, breaks);

test/mjsunit/debug-stepin-builtin.js

@@ -41,14 +41,14 @@ var expected_function_name = null;
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 1) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
-        state = 2;
-      } else if (state == 2) {
+      if (state == 3) {
         assertEquals(expected_function_name, event_data.func().name());
         assertEquals(expected_source_line_text,
                      event_data.sourceLineText());
-        state = 3;
+        state = 4;
+      } else {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
       }
     }
   } catch(e) {
@@ -72,7 +72,7 @@ function testStepInArraySlice() {
 state = 1;
 testStepInArraySlice();
 assertNull(exception);
-assertEquals(3, state);
+assertEquals(4, state);
 
 // Get rid of the debug event listener.
 Debug.setListener(null);

test/mjsunit/debug-stepin-call-function-stub.js

@@ -42,11 +42,11 @@ var step_in_count = 2;
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 0) {
+      if (state < step_in_count) {
         // Step into f().
-        exec_state.prepareStep(Debug.StepAction.StepIn, step_in_count);
-        state = 2;
-      } else if (state == 2) {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
+      } else {
         assertEquals(expected_source_line_text,
                      event_data.sourceLineText());
         assertEquals(expected_function_name, event_data.func().name());

test/mjsunit/debug-stepin-construct-call.js

@@ -12,7 +12,7 @@ function listener(event, exec_state, event_data, data) {
   try {
     var source_line = exec_state.frame(0).sourceLineText();
     print(source_line);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
     break_count++;
   } catch (e) {
     exception = e;

test/mjsunit/debug-stepin-foreach.js

@@ -27,7 +27,7 @@ function listener(event, exec_state, event_data, data) {
                  "Expected: // Break " + break_count + ".");
       ++break_count;
       if (break_count !== expected_breaks) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+        exec_state.prepareStep(Debug.StepAction.StepIn);
       }
     }
   } catch(e) {

test/mjsunit/debug-stepin-function-call.js

@@ -38,11 +38,11 @@ var state = 0;
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 0) {
+      if (state < 2) {
         // Step into f2.call:
-        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
-        state = 2;
-      } else if (state == 2) {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
+      } else {
         assertEquals('g', event_data.func().name());
         assertEquals('  return t + 1; // expected line',
                      event_data.sourceLineText());

test/mjsunit/debug-stepin-property-function-call.js

@@ -38,13 +38,13 @@ var state = 1;
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (state == 1) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
-        state = 2;
-      } else if (state == 2) {
+      if (state < 4) {
+        exec_state.prepareStep(Debug.StepAction.StepIn);
+        state++;
+      } else {
         assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0,
           "source line: \"" + event_data.sourceLineText() + "\"");
-        state = 3;
+        state = 5;
       }
     }
   } catch(e) {
@@ -143,7 +143,7 @@ for (var n in this) {
   this[n]();
   ++functionsCalled;
   assertNull(exception, n);
-  assertEquals(3, state, n);
+  assertEquals(5, state, n);
   assertEquals(functionsCalled, count, n);
 }
 

test/mjsunit/debug-stepout-recursive-function.js

@@ -30,7 +30,6 @@
 Debug = debug.Debug
 
 var exception = null;
-var step_out_count = 1;
 
 // Simple debug event handler which counts the number of breaks hit and steps.
 var break_point_hit_count = 0;
@@ -40,7 +39,7 @@ function listener(event, exec_state, event_data, data) {
       break_point_hit_count++;
       // Continue stepping until returned to bottom frame.
       if (exec_state.frameCount() > 1) {
-        exec_state.prepareStep(Debug.StepAction.StepOut, step_out_count);
+        exec_state.prepareStep(Debug.StepAction.StepOut);
       }
 
     }
@@ -80,27 +79,23 @@ function fact(x) {
 
 BeginTest('Test 1');
 shouldBreak = function(x) { return x == 3; };
-step_out_count = 1;
 fact(3);
 EndTest(2);
 
 BeginTest('Test 2');
 shouldBreak = function(x) { return x == 2; };
-step_out_count = 1;
 fact(3);
 EndTest(3);
 
 BeginTest('Test 3');
 shouldBreak = function(x) { return x == 1; };
-step_out_count = 2;
 fact(3);
-EndTest(2);
+EndTest(4);
 
 BeginTest('Test 4');
 shouldBreak = function(x) { return x == 1 || x == 3; };
-step_out_count = 2;
 fact(3);
-EndTest(3);
+EndTest(5);
 
 // Get rid of the debug event listener.
 Debug.setListener(null);

test/mjsunit/debug-stepout-scope-part1.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part2.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part3.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part4.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part5.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part6.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part7.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-scope-part8.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
     }
 
     // Do steps until we reach the global scope again.
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   }
 }
 

test/mjsunit/debug-stepout-to-builtin.js

@@ -42,9 +42,9 @@ function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
       if (state == 1) {
-        exec_state.prepareStep(Debug.StepAction.StepOut, 2);
-        state = 2;
-      } else if (state == 2) {
+        exec_state.prepareStep(Debug.StepAction.StepOut);
+        state++;
+      } else {
         assertEquals(expected_function_name, event_data.func().name());
         assertEquals(expected_source_line_text,
                      event_data.sourceLineText());

test/mjsunit/es6/debug-break-default-constructor.js

@@ -14,7 +14,7 @@ var step_count = 0;
 function listener(event, execState, eventData, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
-    execState.prepareStep(Debug.StepAction.StepInto);
+    execState.prepareStep(Debug.StepAction.StepIn);
     var s = execState.frame().sourceLineText();
     step_count++;
     assertTrue(s.indexOf('// ' + step_count + '.') >= 0);

test/mjsunit/es6/debug-promises/stepin-constructor.js

@@ -12,7 +12,7 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     breaks.push(exec_state.frame(0).sourceLineText().trimLeft());
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/es6/debug-promises/stepin-handler.js

@@ -27,7 +27,7 @@ function listener(event, exec_state, event_data, data) {
                  "Expected: // Break " + break_count + ".");
       ++break_count;
       if (break_count !== expected_breaks) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+        exec_state.prepareStep(Debug.StepAction.StepIn);
       }
     }
   } catch(e) {

test/mjsunit/es6/debug-step-into-class-extends.js

@@ -14,7 +14,7 @@ var stepCount = 0;
 function listener(event, execState, eventData, data) {
   if (event == Debug.DebugEvent.Break) {
     if (!done) {
-      execState.prepareStep(Debug.StepAction.StepInto);
+      execState.prepareStep(Debug.StepAction.StepIn);
       var s = execState.frame().sourceLineText();
       assertTrue(s.indexOf('// ' + stepCount + '.') !== -1);
       stepCount++;

test/mjsunit/es6/debug-step-into-constructor.js

@@ -12,7 +12,7 @@ var done, stepCount;
 function listener(event, execState, eventData, data) {
   if (event == Debug.DebugEvent.Break) {
     if (!done) {
-      execState.prepareStep(Debug.StepAction.StepInto);
+      execState.prepareStep(Debug.StepAction.StepIn);
       var s = execState.frame().sourceLineText();
       assertTrue(s.indexOf('// ' + stepCount + '.') !== -1);
       stepCount++;

test/mjsunit/es6/debug-step-into-regexp-subclass.js

@@ -15,7 +15,7 @@ function listener(event, exec_state, event_data, data) {
     print(event_data.sourceLineText());
     assertTrue(
         event_data.sourceLineText().indexOf(`Break ${break_count++}.`) > 0);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/es6/debug-stepin-collections-foreach.js

@@ -6,113 +6,95 @@
 
 Debug = debug.Debug
 
-var exception = false;
+var exception = null;
 
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      if (breaks == 0) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 2);
-        breaks = 1;
-      } else if (breaks <= 3) {
-        breaks++;
-        // Check whether we break at the expected line.
-        print(event_data.sourceLineText());
-        assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0);
-        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
-      }
+      exec_state.prepareStep(Debug.StepAction.StepIn);
+      print(event_data.sourceLineText());
+      assertTrue(
+          event_data.sourceLineText().indexOf(`B${breaks++}`) > 0);
     }
   } catch (e) {
-    exception = true;
+    print(e);
+    quit();
+    exception = e;
   }
 }
 
 function cb_set(num) {
-  print("element " + num);  // Expected to step to this point.
-  return true;
-}
+  print("element " + num);  // B2 B5 B8
+  return true;              // B3 B6 B9
+}                           // B4 B7 B10
 
 function cb_map(key, val) {
-  print("key " + key + ", value " + val);  // Expected to step to this point.
-  return true;
-}
+  print("key " + key + ", value " + val);  // B2 B5 B8
+  return true;                             // B3 B6 B9
+}                                          // B4 B7 B10
 
 var s = new Set();
 s.add(1);
 s.add(2);
 s.add(3);
-s.add(4);
 
 var m = new Map();
 m.set('foo', 1);
 m.set('bar', 2);
 m.set('baz', 3);
-m.set('bat', 4);
-
-Debug.setListener(listener);
 
 var breaks = 0;
-debugger;
-s.forEach(cb_set);
-assertFalse(exception);
-assertEquals(4, breaks);
+Debug.setListener(listener);
+debugger;                 // B0
+s.forEach(cb_set);        // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 breaks = 0;
-debugger;
-m.forEach(cb_map);
-assertFalse(exception);
-assertEquals(4, breaks);
-
-Debug.setListener(null);
-
+Debug.setListener(listener);
+debugger;                 // B0
+m.forEach(cb_map);        // B1
+Debug.setListener(null);  // B11
+assertNull(exception);
+assertEquals(12, breaks);
 
 // Test two levels of builtin callbacks:
 // Array.forEach calls a callback function, which by itself uses
 // Array.forEach with another callback function.
 
-function second_level_listener(event, exec_state, event_data, data) {
-  try {
-    if (event == Debug.DebugEvent.Break) {
-      if (breaks == 0) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 3);
-        breaks = 1;
-      } else if (breaks <= 16) {
-        breaks++;
-        // Check whether we break at the expected line.
-        assertTrue(event_data.sourceLineText().indexOf("Expected to step") > 0);
-        // Step two steps further every four breaks to skip the
-        // forEach call in the first level of recurision.
-        var step = (breaks % 4 == 1) ? 6 : 3;
-        exec_state.prepareStep(Debug.StepAction.StepIn, step);
-      }
-    }
-  } catch (e) {
-    exception = true;
-  }
-}
+function cb_set_2(num) {
+  print("element " + num);  // B3 B6 B9  B15 B18 B21 B27 B30 B33
+  return true;              // B4 B7 B10 B16 B19 B22 B28 B31 B34
+}                           // B5 B8 B11 B17 B20 B23 B29 B32 B35
+
+function cb_map_2(k, v) {
+  print(`key ${k}, value ${v}`);  // B3 B6 B9  B15 B18 B21 B27 B30 B33
+  return true;                    // B4 B7 B10 B16 B19 B22 B28 B31 B34
+}                                 // B5 B8 B11 B17 B20 B23 B29 B32 B35
 
 function cb_set_foreach(num) {
-  s.forEach(cb_set);
-  print("back to the first level of recursion.");
-}
+  s.forEach(cb_set_2);      // B2  B14 B26
+  print("back.");           // B12 B24 B36
+}                           // B13 B25 B37
 
 function cb_map_foreach(key, val) {
-  m.forEach(cb_set);
-  print("back to the first level of recursion.");
-}
-
-Debug.setListener(second_level_listener);
+  m.forEach(cb_map_2);      // B2  B14 B26
+  print("back.");           // B12 B24 B36
+}                           // B13 B25 B37
 
 breaks = 0;
-debugger;
-s.forEach(cb_set_foreach);
-assertFalse(exception);
-assertEquals(17, breaks);
+Debug.setListener(listener);
+debugger;                   // B0
+s.forEach(cb_set_foreach);  // B1
+Debug.setListener(null);    // B38
+assertNull(exception);
+assertEquals(39, breaks);
 
 breaks = 0;
-debugger;
-m.forEach(cb_map_foreach);
-assertFalse(exception);
-assertEquals(17, breaks);
-
-Debug.setListener(null);
+Debug.setListener(listener);
+debugger;                   // B0
+m.forEach(cb_map_foreach);  // B1
+Debug.setListener(null);    // B38
+assertNull(exception);
+assertEquals(39, breaks);

test/mjsunit/es6/debug-stepin-generators.js

@@ -15,7 +15,7 @@ function listener(event, exec_state, event_data, data) {
     print(source);
     if (/stop stepping/.test(source)) return;
     if (/yield/.test(source)) yields++;
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     print(e, e.stack);
     exception = e;

test/mjsunit/es6/debug-stepin-microtasks.js

@@ -26,9 +26,9 @@ function listener(event, exec_state, event_data, data) {
                  "Unexpected pause at: " + source + "\n" +
                  "Expected: // Break " + break_count + ".");
       if (source.indexOf("StepOver.") !== -1) {
-        exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+        exec_state.prepareStep(Debug.StepAction.StepNext);
       } else {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+        exec_state.prepareStep(Debug.StepAction.StepIn);
       }
       ++break_count;
     }

test/mjsunit/es6/debug-stepin-string-template.js

@@ -19,7 +19,7 @@ function listener(event, exec_state, event_data, data) {
       entry += exec_state.frame(i).sourceColumn();
     }
     log.push(entry);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/es6/debug-stepnext-for.js

@@ -72,7 +72,7 @@ function listener(event, exec_state, event_data, data) {
     var match = line.match(/\/\/ Break (\w)$/);
     assertEquals(2, match.length);
     log.push(match[1] + col);
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
     break_count++;
   } catch (e) {
     exception = e;

test/mjsunit/es6/regress/regress-468661.js

@@ -44,7 +44,7 @@ function listener(event, exec_state, event_data, data) {
       ++break_count;
 
       if (break_count !== expected_breaks) {
-        exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+        exec_state.prepareStep(Debug.StepAction.StepIn);
         print("Next step prepared");
       }
     }

test/mjsunit/harmony/debug-stepin-default-parameters.js

@@ -19,7 +19,7 @@ function listener(event, exec_state, event_data, data) {
       entry += exec_state.frame(i).sourceColumn();
     }
     log.push(entry);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/harmony/debug-stepin-proxies.js

@@ -19,7 +19,7 @@ function listener(event, exec_state, event_data, data) {
       entry += exec_state.frame(i).sourceColumn();
     }
     log.push(entry);
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/regress/debug-prepare-step-in.js

@@ -30,7 +30,7 @@
 Debug = debug.Debug
 
 function breakListener(event, exec_state, event_data, data) {
-  exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+  exec_state.prepareStep(Debug.StepAction.StepIn);
 }
 
 Debug.setListener(breakListener);

test/mjsunit/regress/regress-109195.js

@@ -32,7 +32,7 @@ function listener(event, exec_state, event_data, data) {
   for (var i = 0, n = exec_state.frameCount(); i < n; i++) {
     exec_state.frame().scopeCount(i);
   }
-  exec_state.prepareStep(Debug.StepAction.Continue, 1);
+  exec_state.prepareStep(Debug.StepAction.StepNext);
 }
 
 Debug.setListener(listener);

test/mjsunit/regress/regress-147497.js

@@ -31,7 +31,7 @@ Debug = debug.Debug;
 
 function listener(event, exec_state, event_data, data) {
   if (event == Debug.DebugEvent.Break) {
-    exec_state.prepareStep(Debug.StepAction.StepNext, 10);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   }
 };
 

test/mjsunit/regress/regress-crbug-119800.js

@@ -19,7 +19,7 @@ function listener(event, exec_state, event_data, data) {
   try {
     Debug.debuggerFlags().breakPointsActive.setValue(false);
     breaks.push(exec_state.frame().sourceLineText().trimLeft());
-    exec_state.prepareStep(Debug.StepAction.StepIn, 1);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
   } catch (e) {
     exception = e;
   }

test/mjsunit/regress/regress-crbug-405922.js

@@ -5,13 +5,15 @@
 // Flags: --allow-natives-syntax --expose-debug-as debug
 
 Debug = debug.Debug
+var exception = null;
 
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
-      exec_state.prepareStep(Debug.StepAction.StepIn, 3);
+      exec_state.prepareStep(Debug.StepAction.StepIn);
     }
   } catch (e) {
+    exception = e;
   }
 }
 
@@ -25,3 +27,4 @@ debugger;
 f(2);
 
 Debug.setListener(null);
+assertNull(exception);

test/mjsunit/regress/regress-crbug-409614.js

@@ -10,7 +10,7 @@ var error_count = 0;
 
 function f() {
   return 0;  // Break
-}
+}            // Break
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
@@ -18,7 +18,7 @@ function listener(event, exec_state, event_data, data) {
     if (exec_state.frame(0).sourceLineText().indexOf("Break") <0) {
       error_count++;
     }
-    exec_state.prepareStep(Debug.StepAction.StepIn, 2);
+    exec_state.prepareStep(Debug.StepAction.StepIn);
     f();  // We should not break in this call of f().
   } catch (e) {
     print(e + e.stack);
@@ -29,7 +29,7 @@ function listener(event, exec_state, event_data, data) {
 Debug.setListener(listener);
 
 debugger;  // Break
-f();
+f();       // Break
 
 Debug.setListener(null);  // Break
 

test/mjsunit/regress/regress-crbug-467180.js

@@ -20,7 +20,7 @@ function listener(event, exec_state, event_data, data) {
     var label = +exec_state.frame(0).sourceLineText().substr(-1);
     log.push(label);
     if (label == 2) log.push(exec_state.frame(0).evaluate("i").value());
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   } catch (e) {
     exception = e;
     print("Caught something. " + e + " " + e.stack);

test/mjsunit/regress/regress-crbug-568477-1.js

@@ -12,7 +12,7 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     log.push(exec_state.frame(0).sourceLineText().trimLeft());
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   } catch (e) {
     %AbortJS(e + "\n" + e.stack);
   }

test/mjsunit/regress/regress-crbug-568477-2.js

@@ -16,7 +16,7 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     assertEquals(expected.shift(), exec_state.frame(0).sourceLineText().trimLeft());
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   } catch (e) {
     %AbortJS(e + "\n" + e.stack);
   }

test/mjsunit/regress/regress-crbug-568477-3.js

@@ -12,7 +12,7 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     log.push(exec_state.frame(0).sourceLineText().trimLeft());
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   } catch (e) {
     %AbortJS(e + "\n" + e.stack);
   }

test/mjsunit/regress/regress-crbug-568477-4.js

@@ -13,7 +13,7 @@ function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     log.push(exec_state.frame(0).sourceLineText().trimLeft());
-    exec_state.prepareStep(Debug.StepAction.StepNext, 1);
+    exec_state.prepareStep(Debug.StepAction.StepNext);
   } catch (e) {
     %AbortJS(e + "\n" + e.stack);
   }