44 lines
1.4 KiB
C++
44 lines
1.4 KiB
C++
/*
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* Copyright (C) 2018 The Android Open Source Project
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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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*/
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#include <stdint.h>
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#include <stdlib.h>
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#include "TestUtils.h"
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// The loop in this function is only guaranteed to not be optimized away by the compiler
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// if optimizations are turned off. This is partially because the compiler doesn't have
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// any idea about the function since it is retrieved using dlsym.
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//
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// In an effort to defend against the compiler:
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// 1. The loop iteration variable is volatile.
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// 2. A call to this function should be wrapped in TestUtils::DoNotOptimize().
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extern "C" int BusyWait() {
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for (size_t i = 0; i < 1000000;) {
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unwindstack::DoNotOptimize(i++);
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}
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return 0;
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}
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// Do a loop that guarantees the terminating leaf frame will be in
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// the this library and not a function from a different library.
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extern "C" void WaitForever() {
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bool run = true;
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while (run) {
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unwindstack::DoNotOptimize(run = true);
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}
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}
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