1 files changed, 82 insertions, 0 deletions
diff --git a/deps/v8/src/wasm/well-known-imports.h b/deps/v8/src/wasm/well-known-imports.h
new file mode 100644
index 0000000000..11c7b46580
--- /dev/null
+++ b/deps/v8/src/wasm/well-known-imports.h
@@ -0,0 +1,82 @@
+// Copyright 2023 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#if !V8_ENABLE_WEBASSEMBLY
+#error This header should only be included if WebAssembly is enabled.
+#endif  // !V8_ENABLE_WEBASSEMBLY
+
+#ifndef V8_WASM_WELL_KNOWN_IMPORTS_H_
+#define V8_WASM_WELL_KNOWN_IMPORTS_H_
+
+#include <memory>
+
+#include "src/base/atomicops.h"
+#include "src/base/platform/mutex.h"
+#include "src/base/vector.h"
+#include "src/common/globals.h"
+
+namespace v8::internal::wasm {
+
+enum class WellKnownImport : uint8_t {
+  kUninstantiated,
+  kGeneric,
+  kStringToLowerCaseStringref,
+};
+
+class NativeModule;
+
+// For debugging/tracing.
+const char* WellKnownImportName(WellKnownImport wki);
+
+class WellKnownImportsList {
+ public:
+  enum class UpdateResult : bool { kFoundIncompatibility, kOK };
+
+  WellKnownImportsList() = default;
+
+  // Regular initialization. Allocates size-dependent internal data.
+  void Initialize(int size) {
+#if DEBUG
+    DCHECK_EQ(-1, size_);
+    size_ = size;
+#endif
+    static_assert(static_cast<int>(WellKnownImport::kUninstantiated) == 0);
+    statuses_ = std::make_unique<std::atomic<WellKnownImport>[]>(size);
+#if !defined(__cpp_lib_atomic_value_initialization) || \
+    __cpp_lib_atomic_value_initialization < 201911L
+    for (int i = 0; i < size; i++) {
+      std::atomic_init(&statuses_.get()[i], WellKnownImport::kUninstantiated);
+    }
+#endif
+  }
+
+  // Intended for deserialization. Does not check consistency with code.
+  void Initialize(base::Vector<const WellKnownImport> entries);
+
+  WellKnownImport get(int index) const {
+    DCHECK_LT(index, size_);
+    return statuses_[index].load(std::memory_order_relaxed);
+  }
+
+  V8_WARN_UNUSED_RESULT UpdateResult
+  Update(base::Vector<WellKnownImport> entries);
+
+  // If you need this mutex and the NativeModule's allocation_mutex_, always
+  // get the latter first.
+  base::Mutex* mutex() { return &mutex_; }
+
+ private:
+  // This mutex guards {statuses_}, for operations that need to ensure that
+  // they see a consistent view of {statutes_} for some period of time.
+  base::Mutex mutex_;
+  std::unique_ptr<std::atomic<WellKnownImport>[]> statuses_;
+
+#if DEBUG
+  int size_{-1};
+#endif
+};
+
+}  // namespace v8::internal::wasm
+
+#endif  // V8_WASM_WELL_KNOWN_IMPORTS_H_