Reland "[debug] add runtime side effect check for StaCurrentContextSlot"

This is a reland of 0340874b

Original change's description:
> [debug] add runtime side effect check for StaCurrentContextSlot
> 
> R=yangguo@chromium.org
> 
> Bug: v8:7588
> Change-Id: If78f6dd460c7423923800a98d44520c1bf71663c
> Reviewed-on: https://chromium-review.googlesource.com/996236
> Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52398}

Bug: v8:7588
Change-Id: Ife6b039ea3291103a54ae04c3007fe4610371c3f
Reviewed-on: https://chromium-review.googlesource.com/998801Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52452}

src/debug/debug-evaluate.cc

@@ -858,6 +858,7 @@ bool BytecodeRequiresRuntimeCheck(interpreter::Bytecode bytecode) {
     case Bytecode::kStaKeyedProperty:
     case Bytecode::kStaInArrayLiteral:
     case Bytecode::kStaDataPropertyInLiteral:
+    case Bytecode::kStaCurrentContextSlot:
       return true;
     default:
       return false;

src/debug/debug.cc

@@ -2413,8 +2413,28 @@ bool Debug::PerformSideEffectCheckForCallback(Handle<Object> callback_info) {
   return false;
 }
 
-bool Debug::PerformSideEffectCheckForObject(Handle<Object> object) {
+bool Debug::PerformSideEffectCheckAtBytecode(InterpretedFrame* frame) {
+  using interpreter::Bytecode;
+
   DCHECK_EQ(isolate_->debug_execution_mode(), DebugInfo::kSideEffects);
+  SharedFunctionInfo* shared = frame->function()->shared();
+  BytecodeArray* bytecode_array = shared->bytecode_array();
+  int offset = frame->GetBytecodeOffset();
+  interpreter::BytecodeArrayAccessor bytecode_accessor(handle(bytecode_array),
+                                                       offset);
+
+  Bytecode bytecode = bytecode_accessor.current_bytecode();
+  interpreter::Register reg;
+  switch (bytecode) {
+    case Bytecode::kStaCurrentContextSlot:
+      reg = interpreter::Register::current_context();
+      break;
+    default:
+      reg = bytecode_accessor.GetRegisterOperand(0);
+      break;
+  }
+  Handle<Object> object =
+      handle(frame->ReadInterpreterRegister(reg.index()), isolate_);
   if (object->IsHeapObject()) {
     Address address = Handle<HeapObject>::cast(object)->address();
     if (temporary_objects_->HasObject(address)) {
@@ -2422,14 +2442,6 @@ bool Debug::PerformSideEffectCheckForObject(Handle<Object> object) {
     }
   }
   if (FLAG_trace_side_effect_free_debug_evaluate) {
-    JavaScriptFrameIterator it(isolate_);
-    InterpretedFrame* interpreted_frame =
-        reinterpret_cast<InterpretedFrame*>(it.frame());
-    SharedFunctionInfo* shared = interpreted_frame->function()->shared();
-    BytecodeArray* bytecode_array = shared->bytecode_array();
-    int bytecode_offset = interpreted_frame->GetBytecodeOffset();
-    interpreter::Bytecode bytecode =
-        interpreter::Bytecodes::FromByte(bytecode_array->get(bytecode_offset));
     PrintF("[debug-evaluate] %s failed runtime side effect check.\n",
            interpreter::Bytecodes::ToString(bytecode));
   }

src/debug/debug.h

@@ -347,7 +347,7 @@ class Debug {
 
   bool PerformSideEffectCheck(Handle<JSFunction> function);
   bool PerformSideEffectCheckForCallback(Handle<Object> callback_info);
-  bool PerformSideEffectCheckForObject(Handle<Object> object);
+  bool PerformSideEffectCheckAtBytecode(InterpretedFrame* frame);
 
   // Flags and states.
   DebugScope* debugger_entry() {

src/runtime/runtime-debug.cc

@@ -59,15 +59,8 @@ RUNTIME_FUNCTION_RETURN_PAIR(Runtime_DebugBreakOnBytecode) {
 
   bool side_effect_check_failed = false;
   if (isolate->debug_execution_mode() == DebugInfo::kSideEffects) {
-    int offset = interpreted_frame->GetBytecodeOffset();
-    interpreter::BytecodeArrayAccessor bytecode_accessor(handle(bytecode_array),
-                                                         offset);
-    interpreter::Register reg = bytecode_accessor.GetRegisterOperand(0);
-    Handle<Object> first_operand = handle(
-        interpreted_frame->ReadInterpreterRegister(reg.index()), isolate);
-    if (!isolate->debug()->PerformSideEffectCheckForObject(first_operand)) {
-      side_effect_check_failed = true;
-    }
+    side_effect_check_failed =
+        !isolate->debug()->PerformSideEffectCheckAtBytecode(interpreted_frame);
   }
 
   if (Bytecodes::Returns(bytecode)) {

test/debugger/debug/side-effect/debug-evaluate-no-side-effect-runtime-check.js

@@ -4,6 +4,13 @@
 
 Debug = debug.Debug;
 
+// StaCurrentContextSlot
+success(10, `(function(){
+  const x = 10;
+  function f1() {return x;}
+  return x;
+})()`);
+
 // StaNamedProperty
 var a = {name: 'foo'};
 function set_name(a) {