[interpreter, debugger] fix remaining cctest failures.

test/cctest/test-debug.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3440 matching lines @@
   DebugLocalContext env;
   v8::Isolate* isolate = env->GetIsolate();
   v8::HandleScope scope(isolate);
 
   // Register a debug event listener which steps and counts.
   v8::Debug::SetDebugEventListener(isolate, DebugEventStep);
 
   v8::Local<v8::Context> context = env.context();
   // Create a function for testing stepping. Run it to allow it to get
   // optimized.
-  const char* src = "function foo(x) { "
-                    "  var a;"
-                    "  a = x ? 1 : 2;"
-                    "  return a;"
-                    "}"
-                    "foo()";
+  const char* src =
+      "function foo(x) { "
+      "  return x ? 1 : 2;"

[vogelheim, 2016/03/15 09:51:51]

Hmm. Not sure, but this might count as cheating... ;-)

This new test case tests exactly what the old one was *meant* to test, so it's
arguably an improvement. But the old test case (accidentally) triggered a
difference in FCG and Ignition breakpoints (via an unrelated optimization in
Ignition), which is valuable in its own right.

Since we've come to the conclusion that this difference is intended (or at least
best we can do for now), I think ideally I'd want a test case that "documents"
this. E.g., the old test case, but with something like:
  CHECK_IMPLIES(FLAG_ignition, 2 == breakpoint_hit_count);
  CHECK_IMPLIES(!FLAG_ignition, 3 == breakpoint_hit_count);


I'm not entirely sure either way, so.. your choice! :)

[Yang, 2016/03/15 10:00:12]

The old version tested both a conditional, and the assignment-and-return combo.
Now It only tests the conditional, and the newly introduced
src/ignition/elided-instruction* tests test the assignment-and-return combo, so
I think we are not losing any test coverage here :)

+      "}"
+      "foo()";
   v8::Local<v8::Function> foo = CompileFunction(&env, src, "foo");
   SetBreakPoint(foo, 0);  // "var a;"
 
   step_action = StepIn;
   break_point_hit_count = 0;
   foo->Call(context, env->Global(), 0, NULL).ToLocalChecked();
-  CHECK_EQ(3, break_point_hit_count);
+  CHECK_EQ(2, break_point_hit_count);
 
   step_action = StepIn;
   break_point_hit_count = 0;
   const int argc = 1;
   v8::Local<v8::Value> argv_true[argc] = {v8::True(isolate)};
   foo->Call(context, env->Global(), argc, argv_true).ToLocalChecked();
-  CHECK_EQ(3, break_point_hit_count);
+  CHECK_EQ(2, break_point_hit_count);
 
   // Get rid of the debug event listener.
   v8::Debug::SetDebugEventListener(isolate, nullptr);
   CheckDebuggerUnloaded(isolate);
 }
 
 
 TEST(StepInOutSimple) {
   DebugLocalContext env;
   v8::HandleScope scope(env->GetIsolate());
@@ skipping 4573 matching lines @@
   CHECK_EQ(22, iterator->GetBreakLocation().position());
   iterator->Next();
   CHECK(iterator->GetBreakLocation().IsReturn());
   CHECK_EQ(50, iterator->GetBreakLocation().position());
   iterator->Next();
   CHECK(iterator->Done());
   delete iterator;
 
   DisableDebugger(isolate);
 }