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https://github.com/encounter/dawn-cmake.git
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083a1ce2bf
This changes RefCounted to increment and decrement the refcount by steps of 2, so that a 1 bit payload can be inlined in the refcount. This avoids using a whole boolean + padding (4 or 8 bytes in general) to know if objects are errors. Fixes a longstanding optimization TODO. BUG=dawn:105 Change-Id: I5e8f66465d23772fb6082ea3e0d5d4aba2132648 Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/13680 Commit-Queue: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
59 lines
2.0 KiB
C++
59 lines
2.0 KiB
C++
// Copyright 2017 The Dawn Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "dawn_native/RefCounted.h"
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#include "common/Assert.h"
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namespace dawn_native {
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static constexpr size_t kPayloadBits = 1;
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static constexpr uint64_t kPayloadMask = (uint64_t(1) << kPayloadBits) - 1;
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static constexpr uint64_t kRefCountIncrement = (uint64_t(1) << kPayloadBits);
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RefCounted::RefCounted(uint64_t payload) : mRefCount(kRefCountIncrement + payload) {
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ASSERT((payload & kPayloadMask) == payload);
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}
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RefCounted::~RefCounted() {
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}
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uint64_t RefCounted::GetRefCountForTesting() const {
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return mRefCount >> kPayloadBits;
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}
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uint64_t RefCounted::GetRefCountPayload() const {
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// We only care about the payload bits of the refcount. These never change after
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// initialization so we can use the relaxed memory order. The order doesn't guarantee
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// anything except the atomicity of the load, which is enough since any past values of the
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// atomic will have the correct payload bits.
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return kPayloadMask & mRefCount.load(std::memory_order_relaxed);
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}
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void RefCounted::Reference() {
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ASSERT((mRefCount & ~kPayloadMask) != 0);
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mRefCount += kRefCountIncrement;
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}
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void RefCounted::Release() {
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ASSERT((mRefCount & ~kPayloadMask) != 0);
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mRefCount -= kRefCountIncrement;
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if (mRefCount < kRefCountIncrement) {
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delete this;
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}
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}
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} // namespace dawn_native
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