65893d84e5
Some types of supported low-level write barrier only requires passing a slot, which may not be even part of a heap object but stack. This complicates the situation, as even with caged heap, there's no way to distinguish a stack and heap slot. Solve this by passing an optional callback that can lazy be used to get the heap. This can be used by the embedder to retrieve the heap from e.g. TLS if needed. This aligns the barrier with Oilpan in Blink. Bug: chromium:1056170 Change-Id: I1e5d022ab17a2614a67b6ef39ed12691bcbd0ac6 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2675924 Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Reviewed-by: Omer Katz <omerkatz@chromium.org> Commit-Queue: Michael Lippautz <mlippautz@chromium.org> Cr-Commit-Position: refs/heads/master@{#72550}
33 lines
945 B
C++
33 lines
945 B
C++
// Copyright 2021 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef INCLUDE_CPPGC_SENTINEL_POINTER_H_
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#define INCLUDE_CPPGC_SENTINEL_POINTER_H_
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#include <cstdint>
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namespace cppgc {
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namespace internal {
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// Special tag type used to denote some sentinel member. The semantics of the
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// sentinel is defined by the embedder.
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struct SentinelPointer {
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template <typename T>
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operator T*() const { // NOLINT
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static constexpr intptr_t kSentinelValue = 1;
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return reinterpret_cast<T*>(kSentinelValue);
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}
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// Hidden friends.
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friend bool operator==(SentinelPointer, SentinelPointer) { return true; }
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friend bool operator!=(SentinelPointer, SentinelPointer) { return false; }
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};
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} // namespace internal
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constexpr internal::SentinelPointer kSentinelPointer;
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} // namespace cppgc
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#endif // INCLUDE_CPPGC_SENTINEL_POINTER_H_
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