1c06165c9b
`std::align` is heavily used in memory allocators. When we attempted to switch from libstdc++ to libc++, we observed a **50%** performance regression in a database query bench: the issue is that `std::align` in libc++ is not an inline function, which prevents the compiler from performing inlining optimizations. make `std::align` an inline function will run about 2x faster. See [benchmark result](https://quick-bench.com/q/wPTnt9JCGn2S-3bu5gY9YrEf6KU). --------- Co-authored-by: Louis Dionne <ldionne.2@gmail.com>
40 lines
1.1 KiB
C++
40 lines
1.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03
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#include <memory>
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#include <iostream>
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#include "benchmark/benchmark.h"
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struct Input {
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std::size_t align;
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std::size_t size;
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void* ptr;
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std::size_t buffer_size;
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};
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static void BM_align(benchmark::State& state) {
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char buffer[1024];
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Input input{};
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void* ptr = buffer + 123;
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std::size_t buffer_size = sizeof(buffer) - 123;
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input.align = state.range();
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input.size = state.range();
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for (auto _ : state) {
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input.ptr = ptr;
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input.buffer_size = buffer_size;
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benchmark::DoNotOptimize(input);
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benchmark::DoNotOptimize(std::align(input.align, input.size, input.ptr, input.buffer_size));
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}
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}
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BENCHMARK(BM_align)->Range(1, 256);
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BENCHMARK_MAIN();
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