From c981f7fce1bf30cbf0d2e52dd1c20dbac28c18f8 Mon Sep 17 00:00:00 2001
From: Matheus Marchini <mmarchini@netflix.com>
Date: Mon, 13 Jan 2020 17:23:58 -0800
Subject: [PATCH] src: guess Symbol.name offset

PR-URL: https://github.com/nodejs/llnode/pull/330
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
---
 src/llv8-constants.cc | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/llv8-constants.cc b/src/llv8-constants.cc
index 9c68b78f..4fb97e26 100644
--- a/src/llv8-constants.cc
+++ b/src/llv8-constants.cc
@@ -550,7 +550,24 @@ void Frame::Load() {
 
 
 void Symbol::Load() {
-  kNameOffset = LoadConstant({"class_Symbol__name__Object"});
+  // map is the last field of HeapObject
+  Constant<int64_t> maybe_name_offset =
+      LoadConstant({"class_HeapObject__map__Map"});
+  common_->Load();
+  if (maybe_name_offset.Check()) {
+    int name_offset = *maybe_name_offset;
+
+    name_offset += common_->kPointerSize;
+    // class Name extends HeapObject and has only one uint32 field
+    name_offset += sizeof(uint32_t);
+    // class Symbol extends Name and has one int32 field before name
+    name_offset += sizeof(int32_t);
+
+    kNameOffset =
+        LoadOptionalConstant({"class_Symbol__name__Object"}, name_offset);
+  } else {
+    kNameOffset = LoadConstant({"class_Symbol__name__Object"});
+  }
 }