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

src/debug/debug-evaluate.cc

Index: src/debug/debug-evaluate.cc
diff --git a/src/debug/debug-evaluate.cc b/src/debug/debug-evaluate.cc
index e93b5952c876ad2ffc7ae80579cf7ed08520efbb..d521aa46dd29c7c2a30ea7cb077afc5b5015b51b 100644
--- a/src/debug/debug-evaluate.cc
+++ b/src/debug/debug-evaluate.cc
@@ -12,6 +12,8 @@
 #include "src/debug/debug.h"
 #include "src/frames-inl.h"
 #include "src/globals.h"
+#include "src/interpreter/bytecode-array-iterator.h"
+#include "src/interpreter/bytecodes.h"
 #include "src/isolate-inl.h"
 
 namespace v8 {
@@ -92,9 +94,13 @@ MaybeHandle<Object> DebugEvaluate::Evaluate(
       Object);
 
   Handle<Object> result;
-  ASSIGN_RETURN_ON_EXCEPTION(
-      isolate, result, Execution::Call(isolate, eval_fun, receiver, 0, NULL),
-      Object);
+  {
+    ReadOnlyEvaluate readonly_evaluate(isolate->debug(),
+                                       FLAG_readonly_debug_evaluate);
+    ASSIGN_RETURN_ON_EXCEPTION(
+        isolate, result, Execution::Call(isolate, eval_fun, receiver, 0, NULL),
+        Object);
+  }
 
   // Skip the global proxy as it has no properties and always delegates to the
   // real global object.
@@ -249,5 +255,23 @@ void DebugEvaluate::ContextBuilder::MaterializeReceiver(
   JSObject::SetOwnPropertyIgnoreAttributes(target, name, recv, NONE).Check();
 }
 
+bool DebugEvaluate::IsReadOnly(Handle<BytecodeArray> bytecode_array) {
+  if (FLAG_trace_readonly_debug_evaluate) {
+    PrintF("[ro] Checking bytecode array\n");
+    bytecode_array->Print();
+  }
+  for (interpreter::BytecodeArrayIterator it(bytecode_array); !it.done();
+       it.Advance()) {
+    if (!interpreter::Bytecodes::BytecodeIsReadOnly(it.current_bytecode())) {
+      if (FLAG_trace_readonly_debug_evaluate) {
+        PrintF("[ro] %s is not a read-only bytecode.\n",
+               interpreter::Bytecodes::ToString(it.current_bytecode()));
+      }
+      return false;
+    }
+  }
+  return true;
+}
+
 }  // namespace internal
 }  // namespace v8