From 1d2a5bed03f21610c96b3e117d7bc9e1e8dcc798 Mon Sep 17 00:00:00 2001
From: "Gang Zhao (Hermes)" <zhaogang@meta.com>
Date: Thu, 14 Nov 2024 13:12:50 -0800
Subject: [PATCH] Pass the pointer of owning object in ctor of GCPointer
 (#1503)

Summary: Pull Request resolved: https://github.com/facebook/hermes/pull/1503

Differential Revision: D62227037
---
 include/hermes/VM/GCPointer-inline.h | 19 +++++++++++++++++++
 include/hermes/VM/GCPointer.h        | 24 +++++++++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/include/hermes/VM/GCPointer-inline.h b/include/hermes/VM/GCPointer-inline.h
index 250fc0c3581..06f14031e31 100644
--- a/include/hermes/VM/GCPointer-inline.h
+++ b/include/hermes/VM/GCPointer-inline.h
@@ -32,6 +32,25 @@ GCPointerBase::GCPointerBase(
   }
 }
 
+template <typename NeedsBarriers>
+GCPointerBase::GCPointerBase(
+    PointerBase &base,
+    GCCell *ptr,
+    GC &gc,
+    const GCCell *owningObj,
+    NeedsBarriers)
+    : CompressedPointer(CompressedPointer::encode(ptr, base)) {
+  assert(
+      (!ptr || gc.validPointer(ptr)) &&
+      "Cannot construct a GCPointer from an invalid pointer");
+  (void)owningObj;
+  if constexpr (NeedsBarriers::value) {
+    gc.constructorWriteBarrier(this, ptr);
+  } else {
+    assert(!gc.needsWriteBarrier(this, ptr));
+  }
+}
+
 template <
     GCPointerBase::MaybeLargeObj maybeLargeObj,
     GCPointerBase::NonNull nonNull>
diff --git a/include/hermes/VM/GCPointer.h b/include/hermes/VM/GCPointer.h
index eb51e29631d..589f755aa31 100644
--- a/include/hermes/VM/GCPointer.h
+++ b/include/hermes/VM/GCPointer.h
@@ -27,6 +27,14 @@ class GCPointerBase : public CompressedPointer {
   template <typename NeedsBarriers>
   inline GCPointerBase(PointerBase &base, GCCell *ptr, GC &gc, NeedsBarriers);
 
+  template <typename NeedsBarriers>
+  inline GCPointerBase(
+      PointerBase &base,
+      GCCell *ptr,
+      GC &gc,
+      const GCCell *owningObj,
+      NeedsBarriers);
+
  public:
   // These classes are used as arguments to GCPointer constructors, to
   // indicate whether write barriers are necessary in initializing the
@@ -99,12 +107,26 @@ class GCPointer : public GCPointerBase {
   template <typename NeedsBarriers>
   GCPointer(PointerBase &base, T *ptr, GC &gc, NeedsBarriers needsBarriers)
       : GCPointerBase(base, ptr, gc, needsBarriers) {}
+  /// Pass the owning object pointer to perform barriers when the object
+  /// supports large allocation.
+  template <typename NeedsBarriers>
+  GCPointer(
+      PointerBase &base,
+      T *ptr,
+      GC &gc,
+      const GCCell *owningObj,
+      NeedsBarriers needsBarriers)
+      : GCPointerBase(base, ptr, gc, owningObj, needsBarriers) {}
 
   /// Same as the constructor above, with the default for
   /// NeedsBarriers as "YesBarriers".  (We can't use default template
   /// arguments with the idiom used above.)
-  inline GCPointer(PointerBase &base, T *ptr, GC &gc)
+  GCPointer(PointerBase &base, T *ptr, GC &gc)
       : GCPointer<T>(base, ptr, gc, YesBarriers()) {}
+  /// Pass the owning object pointer to perform barriers when the object
+  /// supports large allocation.
+  GCPointer(PointerBase &base, T *ptr, GC &gc, const GCCell *owningObj)
+      : GCPointer<T>(base, ptr, gc, owningObj, YesBarriers()) {}
 
   /// We are not allowed to copy-construct or assign GCPointers.
   GCPointer(const GCPointerBase &) = delete;