Revert "Reland "cppgc: Enable checks for assignments in prefinalizers""

This reverts commit adb6276f.

Reason for revert: Broke several blink unit tests, see
https://ci.chromium.org/ui/p/chromium/builders/ci/linux-chromeos-dbg/25255/overview
for an example

Original change's description:
> Reland "cppgc: Enable checks for assignments in prefinalizers"
>
> This is a reland of edcc8ff5
>
> Cause for previous revert was addressed by crbug.com/1241773.
>
> Original change's description:
> > cppgc: Enable checks for assignments in prefinalizers
> >
> > Bug: v8:11749
> > Change-Id: Ic027f732030fb6a2befeffeca9db2eacfd0830a5
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3099953
> > Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> > Commit-Queue: Omer Katz <omerkatz@chromium.org>
> > Cr-Commit-Position: refs/heads/main@{#76370}
>
> Bug: v8:11749
> Change-Id: I57fc138ace002d41e54f7f70250e4d19bc9262b0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3122153
> Auto-Submit: Omer Katz <omerkatz@chromium.org>
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Omer Katz <omerkatz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76553}

Bug: v8:11749
Change-Id: Icc6a3e56d54c22de943b498c2fd6d57f3ef33f96
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3128562
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Fergus Dall <sidereal@google.com>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76558}

BUILD.bazel

@@ -165,6 +165,7 @@ config_setting(
 # v8_control_flow_integrity
 # v8_enable_virtual_memory_cage
 # cppgc_enable_caged_heap
+# cppgc_enable_check_assignments_in_prefinalizers
 # cppgc_enable_object_names
 # cppgc_enable_verify_heap
 # cppgc_enable_young_generation

BUILD.gn

@@ -293,6 +293,10 @@ declare_args() {
   # Enables additional heap verification phases and checks.
   cppgc_enable_verify_heap = ""
 
+  # Enable assignment checks for Members/Persistents during prefinalizer invocations.
+  # TODO(v8:11749): Enable by default after fixing any existing issues in Blink.
+  cppgc_enable_check_assignments_in_prefinalizers = false
+
   # Enable young generation in cppgc.
   cppgc_enable_young_generation = false
 
@@ -776,6 +780,10 @@ config("features") {
     defines += [ "CPPGC_VERIFY_HEAP" ]
   }
 
+  if (cppgc_enable_check_assignments_in_prefinalizers) {
+    defines += [ "CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS" ]
+  }
+
   if (v8_embedder_string != "") {
     defines += [ "V8_EMBEDDER_STRING=\"$v8_embedder_string\"" ]
   }

src/heap/cppgc/pointer-policies.cc

@@ -68,7 +68,7 @@ void EnabledCheckingPolicy::CheckPointerImpl(const void* ptr,
     DCHECK(!header->IsFree());
   }
 
-#ifdef CPPGC_VERIFY_HEAP
+#ifdef CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS
   if (heap_->prefinalizer_handler()->IsInvokingPreFinalizers()) {
     // During prefinalizers invocation, check that |ptr| refers to a live object
     // and that it is assigned to a live slot.
@@ -81,7 +81,7 @@ void EnabledCheckingPolicy::CheckPointerImpl(const void* ptr,
     DCHECK(slot_is_live);
     USE(slot_is_live);
   }
-#endif  // CPPGC_VERIFY_HEAP
+#endif  // CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS
 }
 
 PersistentRegion& StrongPersistentPolicy::GetPersistentRegion(

test/unittests/heap/cppgc/prefinalizer-unittest.cc

@@ -285,7 +285,7 @@ class GCedHolder : public GarbageCollected<GCedHolder> {
 }  // namespace
 
 #if V8_ENABLE_CHECKS
-#ifdef CPPGC_VERIFY_HEAP
+#ifdef CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS
 
 TEST_F(PrefinalizerDeathTest, PrefinalizerCantRewireGraphWithDeadObjects) {
   Persistent<LinkedNode> root{MakeGarbageCollected<LinkedNode>(
@@ -318,7 +318,7 @@ TEST_F(PrefinalizerDeathTest, PrefinalizerCantRessurectObjectOnHeap) {
   EXPECT_DEATH_IF_SUPPORTED(PreciseGC(), "");
 }
 
-#endif  // CPPGC_VERIFY_HEAP
+#endif  // CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS
 #endif  // V8_ENABLE_CHECKS
 
 }  // namespace internal

tools/cppgc/gen_cmake.py

@@ -245,6 +245,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 option(CPPGC_ENABLE_OBJECT_NAMES "Enable object names in cppgc for debug purposes" OFF)
 option(CPPGC_ENABLE_CAGED_HEAP "Enable heap reservation of size 4GB, only possible for 64bit archs" OFF)
 option(CPPGC_ENABLE_VERIFY_HEAP "Enables additional heap verification phases and checks" OFF)
+option(CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS " Enable assignment checks for Members/Persistents during prefinalizer invocations" OFF)
 option(CPPGC_ENABLE_YOUNG_GENERATION "Enable young generation in cppgc" OFF)
 set(CPPGC_TARGET_ARCH "x64" CACHE STRING "Target architecture, possible options: x64, x86, arm, arm64, ppc64, s390x, mipsel, mips64el")
 
@@ -437,6 +438,9 @@ endif()
 if(CPPGC_ENABLE_VERIFY_HEAP)
   target_compile_definitions({target.name} PRIVATE "-DCPPGC_ENABLE_VERIFY_HEAP")
 endif()
+if(CPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS)
+  target_compile_definitions({target.name} PRIVATE "-DCPPGC_CHECK_ASSIGNMENTS_IN_PREFINALIZERS")
+endif()
 if(CPPGC_ENABLE_YOUNG_GENERATION)
   target_compile_definitions({target.name} PRIVATE "-DCPPGC_YOUNG_GENERATION")
 endif()"""