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llvm-project/libcxx/benchmarks/Utilities.h

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Improve codegen for deque. This patch rewrites a few loops in deque and split_buffer to better optimize the codegen. For constructors like `deque<unsigned char> d(500000, 0);` this patch results in a 2x speedup. The patch improves the codegen in roughly three ways: 1. Changes do { ... } while (...) loops into more typical for loops. The optimizer can reason about normal looking loops better. 2. Split the iteration over a range into (A) iteration over the blocks, then (B) iteration within the block. This nested structure helps LLVM lower the inner loop to `memset`. 3. Do fewer things each iteration. Some of these loops were incrementing or changing 4-5 variables every loop (in addition to the construction). Previously most loops would increment the end pointer, the size, and decrement the count of remaining items to construct. Now we only increment a single pointer for most iterations. llvm-svn: 368547
2019-08-12 15:51:05 +08:00
// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
libcxx: Rename .hpp files in libcxx/benchmarks to .h LLVM uses .h as its extension for header files. Differential Revision: https://reviews.llvm.org/D66509 llvm-svn: 369487
2019-08-21 09:59:12 +08:00
#ifndef BENCHMARK_UTILITIES_H
#define BENCHMARK_UTILITIES_H
Improve codegen for deque. This patch rewrites a few loops in deque and split_buffer to better optimize the codegen. For constructors like `deque<unsigned char> d(500000, 0);` this patch results in a 2x speedup. The patch improves the codegen in roughly three ways: 1. Changes do { ... } while (...) loops into more typical for loops. The optimizer can reason about normal looking loops better. 2. Split the iteration over a range into (A) iteration over the blocks, then (B) iteration within the block. This nested structure helps LLVM lower the inner loop to `memset`. 3. Do fewer things each iteration. Some of these loops were incrementing or changing 4-5 variables every loop (in addition to the construction). Previously most loops would increment the end pointer, the size, and decrement the count of remaining items to construct. Now we only increment a single pointer for most iterations. llvm-svn: 368547
2019-08-12 15:51:05 +08:00
#include <cassert>
#include <type_traits>
#include "benchmark/benchmark.h"
namespace UtilitiesInternal {
template <class Container>
auto HaveDataImpl(int) -> decltype((std::declval<Container&>().data(), std::true_type{}));
template <class Container>
auto HaveDataImpl(long) -> std::false_type;
template <class T>
using HasData = decltype(HaveDataImpl<T>(0));
} // namespace UtilitiesInternal
template <class Container, std::enable_if_t<UtilitiesInternal::HasData<Container>::value>* = nullptr>
void DoNotOptimizeData(Container &c) { benchmark::DoNotOptimize(c.data()); }
template <class Container, std::enable_if_t<!UtilitiesInternal::HasData<Container>::value>* = nullptr>
void DoNotOptimizeData(Container &c) { benchmark::DoNotOptimize(&c); }
libcxx: Rename .hpp files in libcxx/benchmarks to .h LLVM uses .h as its extension for header files. Differential Revision: https://reviews.llvm.org/D66509 llvm-svn: 369487
2019-08-21 09:59:12 +08:00
#endif // BENCHMARK_UTILITIES_H