[debugger] infrastructure for side-effect-free debug-evaluate.

src/runtime/runtime-debug.cc

Index: src/runtime/runtime-debug.cc
diff --git a/src/runtime/runtime-debug.cc b/src/runtime/runtime-debug.cc
index 281ba29695d54ebd8d26aba7376706641180dbc9..af234b56cddc9b42ecb99fb4758424788fa979b2 100644
--- a/src/runtime/runtime-debug.cc
+++ b/src/runtime/runtime-debug.cc
@@ -5,6 +5,7 @@
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
+#include "src/compiler.h"
 #include "src/debug/debug-evaluate.h"
 #include "src/debug/debug-frames.h"
 #include "src/debug/debug-scopes.h"
@@ -1846,14 +1847,18 @@ RUNTIME_FUNCTION(Runtime_ScriptSourceLine) {
   return *str;
 }
 
-// Set one shot breakpoints for the callback function that is passed to a
-// built-in function such as Array.forEach to enable stepping into the callback,
-// if we are indeed stepping and the callback is subject to debugging.
-RUNTIME_FUNCTION(Runtime_DebugPrepareStepInIfStepping) {
+// Perform %DebugPrepareStepInIfStepping and a read-only check.

[jgruber, 2017/01/11 16:12:39]

This comment is out of date.

[Yang, 2017/01/12 06:04:51]

Done.

+RUNTIME_FUNCTION(Runtime_DebugOnFunctionCall) {
   HandleScope scope(isolate);
   DCHECK_EQ(1, args.length());
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, fun, 0);
-  isolate->debug()->PrepareStepIn(fun);
+  if (isolate->debug()->last_step_action() >= StepIn) {
+    isolate->debug()->PrepareStepIn(fun);
+  }
+  if (isolate->needs_side_effect_check() &&
+      !isolate->debug()->PerformSideEffectCheck(fun)) {
+    return isolate->heap()->exception();
+  }
   return isolate->heap()->undefined_value();
 }