зеркало из https://github.com/mozilla/gecko-dev.git
62 строки
1.9 KiB
C++
62 строки
1.9 KiB
C++
// Copyright 2015 Google Inc. All rights reserved.
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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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#ifndef GTEST_BLACKBOX_H
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#define GTEST_BLACKBOX_H
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#include "mozilla/Attributes.h"
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#if defined(_MSC_VER)
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#include <intrin.h>
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#endif // _MSC_VER
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namespace mozilla {
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#if defined(_MSC_VER)
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char volatile* UseCharPointer(char volatile*);
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MOZ_ALWAYS_INLINE_EVEN_DEBUG void* BlackBoxVoidPtr(void* aPtr) {
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aPtr = const_cast<char*>(UseCharPointer(reinterpret_cast<char*>(aPtr)));
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_ReadWriteBarrier();
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return aPtr;
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}
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#else
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// See: https://youtu.be/nXaxk27zwlk?t=2441
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MOZ_ALWAYS_INLINE_EVEN_DEBUG void* BlackBoxVoidPtr(void* aPtr) {
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// "g" is what we want here, but the comment in the Google
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// benchmark code suggests that GCC likes "i,r,m" better.
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// However, on Mozilla try server i,r,m breaks GCC but g
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// works in GCC, so using g for both clang and GCC.
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// godbolt.org indicates that g works already in GCC 4.9,
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// which is the oldest GCC we support at the time of this
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// code landing. godbolt.org suggests that this clearly
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// works is LLVM 5, but it's unclear if this inhibits
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// all relevant optimizations properly on earlier LLVM.
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asm volatile("" : "+g"(aPtr) : "g"(aPtr) : "memory");
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return aPtr;
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}
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#endif // _MSC_VER
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template<class T>
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MOZ_ALWAYS_INLINE_EVEN_DEBUG T* BlackBox(T* aPtr) {
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return static_cast<T*>(BlackBoxVoidPtr(aPtr));
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}
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} // namespace mozilla
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#endif // GTEST_BLACKBOX_H
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