[ro-heap] Remove ReadOnlyHeap::Instance

This removes the static ReadOnlyHeap::Instance method replacing it with
PopulateReadOnlySpaceStatistics on the way to removing the global
ReadOnlyHeap object.

Bug: v8:10454
Change-Id: Ic78c898ff99c6a7dac023d2b5230fbbbf6f36f46
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2179805
Commit-Queue: Dan Elphick <delphick@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67545}

include/v8.h

@@ -123,19 +123,21 @@ namespace internal {
 enum class ArgumentsType;
 template <ArgumentsType>
 class Arguments;
+template <typename T>
+class CustomArguments;
 class DeferredHandles;
+class FunctionCallbackArguments;
+class GlobalHandles;
 class Heap;
 class HeapObject;
 class ExternalString;
 class Isolate;
 class LocalEmbedderHeapTracer;
 class MicrotaskQueue;
-struct ScriptStreamingData;
-template<typename T> class CustomArguments;
 class PropertyCallbackArguments;
-class FunctionCallbackArguments;
-class GlobalHandles;
+class ReadOnlyHeap;
 class ScopedExternalStringLock;
+struct ScriptStreamingData;
 class ThreadLocalTop;
 
 namespace wasm {
@@ -7557,6 +7559,7 @@ class V8_EXPORT SharedMemoryStatistics {
   size_t read_only_space_physical_size_;
 
   friend class V8;
+  friend class internal::ReadOnlyHeap;
 };
 
 /**

src/api/api.cc

@@ -5803,17 +5803,7 @@ void v8::V8::InitializeExternalStartupDataFromFile(const char* snapshot_blob) {
 const char* v8::V8::GetVersion() { return i::Version::GetVersion(); }
 
 void V8::GetSharedMemoryStatistics(SharedMemoryStatistics* statistics) {
-#ifdef V8_SHARED_RO_HEAP
-  i::ReadOnlySpace* ro_space = i::ReadOnlyHeap::Instance()->read_only_space();
-  statistics->read_only_space_size_ = ro_space->CommittedMemory();
-  statistics->read_only_space_used_size_ = ro_space->SizeOfObjects();
-  statistics->read_only_space_physical_size_ =
-      ro_space->CommittedPhysicalMemory();
-#else
-  statistics->read_only_space_size_ = 0;
-  statistics->read_only_space_used_size_ = 0;
-  statistics->read_only_space_physical_size_ = 0;
-#endif  // V8_SHARED_RO_HEAP
+  i::ReadOnlyHeap::PopulateReadOnlySpaceStatistics(statistics);
 }
 
 template <typename ObjectType>

src/heap/read-only-heap.cc

@@ -6,6 +6,7 @@
 
 #include <cstring>
 
+#include "include/v8.h"
 #include "src/base/lazy-instance.h"
 #include "src/base/lsan.h"
 #include "src/base/platform/mutex.h"
@@ -160,10 +161,24 @@ void ReadOnlyHeap::OnHeapTearDown() {
 #endif
 }
 
-#ifdef V8_SHARED_RO_HEAP
 // static
-const ReadOnlyHeap* ReadOnlyHeap::Instance() { return shared_ro_heap_; }
-#endif
+void ReadOnlyHeap::PopulateReadOnlySpaceStatistics(
+    SharedMemoryStatistics* statistics) {
+  statistics->read_only_space_size_ = 0;
+  statistics->read_only_space_used_size_ = 0;
+  statistics->read_only_space_physical_size_ = 0;
+#ifdef V8_SHARED_RO_HEAP
+  std::shared_ptr<ReadOnlyArtifacts> artifacts =
+      read_only_artifacts_.Get().lock();
+  if (artifacts) {
+    auto ro_space = artifacts->shared_read_only_space();
+    statistics->read_only_space_size_ = ro_space->CommittedMemory();
+    statistics->read_only_space_used_size_ = ro_space->SizeOfObjects();
+    statistics->read_only_space_physical_size_ =
+        ro_space->CommittedPhysicalMemory();
+  }
+#endif  // V8_SHARED_RO_HEAP
+}
 
 // static
 bool ReadOnlyHeap::Contains(Address address) {

src/heap/read-only-heap.h

@@ -15,6 +15,9 @@
 #include "src/roots/roots.h"
 
 namespace v8 {
+
+class SharedMemoryStatistics;
+
 namespace internal {
 
 class Isolate;
@@ -47,10 +50,10 @@ class ReadOnlyHeap final {
   // Indicates that the current isolate no longer requires the read-only heap
   // and it may be safely disposed of.
   void OnHeapTearDown();
-
-#ifdef V8_SHARED_RO_HEAP
-  static const ReadOnlyHeap* Instance();
-#endif
+  // If the read-only heap is shared, then populate |statistics| with its stats,
+  // otherwise the read-only heap stats are set to 0.
+  static void PopulateReadOnlySpaceStatistics(
+      SharedMemoryStatistics* statistics);
 
   // Returns whether the address is within the read-only space.
   V8_EXPORT_PRIVATE static bool Contains(Address address);