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llvm-mirror/unittests/Support/ParallelTest.cpp
Reid Kleckner 98666b7f54 Add parallelTransformReduce and parallelForEachError
parallelTransformReduce is modelled on the C++17 pstl API of
std::transform_reduce, except our wrappers do not use execution policy
parameters.

parallelForEachError allows loops that contain potentially failing
operations to propagate errors out of the loop. This was one of the
major challenges I encountered while parallelizing PDB type merging in
LLD. Parallelizing a loop with parallelForEachError is not behavior
preserving: the loop will no longer stop on the first error, it will
continue working and report all errors it encounters in a list.

I plan to use this to propagate errors out of LLD's
coff::TpiSource::remapTpiWithGHashes, which currently stores errors an
error in the TpiSource object.

Differential Revision: https://reviews.llvm.org/D90639
2020-11-02 16:50:14 -08:00

96 lines
3.1 KiB
C++

//===- llvm/unittest/Support/ParallelTest.cpp -----------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Parallel.h unit tests.
///
//===----------------------------------------------------------------------===//
#include "llvm/Support/Parallel.h"
#include "gtest/gtest.h"
#include <array>
#include <random>
uint32_t array[1024 * 1024];
using namespace llvm;
// Tests below are hanging up on mingw. Investigating.
#if !defined(__MINGW32__)
TEST(Parallel, sort) {
std::mt19937 randEngine;
std::uniform_int_distribution<uint32_t> dist;
for (auto &i : array)
i = dist(randEngine);
parallelSort(std::begin(array), std::end(array));
ASSERT_TRUE(llvm::is_sorted(array));
}
TEST(Parallel, parallel_for) {
// We need to test the case with a TaskSize > 1. We are white-box testing
// here. The TaskSize is calculated as (End - Begin) / 1024 at the time of
// writing.
uint32_t range[2050];
std::fill(range, range + 2050, 1);
parallelForEachN(0, 2049, [&range](size_t I) { ++range[I]; });
uint32_t expected[2049];
std::fill(expected, expected + 2049, 2);
ASSERT_TRUE(std::equal(range, range + 2049, expected));
// Check that we don't write past the end of the requested range.
ASSERT_EQ(range[2049], 1u);
}
TEST(Parallel, TransformReduce) {
// Sum an empty list, check that it works.
auto identity = [](uint32_t v) { return v; };
uint32_t sum = parallelTransformReduce(ArrayRef<uint32_t>(), 0U,
std::plus<uint32_t>(), identity);
EXPECT_EQ(sum, 0U);
// Sum the lengths of these strings in parallel.
const char *strs[] = {"a", "ab", "abc", "abcd", "abcde", "abcdef"};
size_t lenSum =
parallelTransformReduce(strs, static_cast<size_t>(0), std::plus<size_t>(),
[](const char *s) { return strlen(s); });
EXPECT_EQ(lenSum, static_cast<size_t>(21));
// Check that we handle non-divisible task sizes as above.
uint32_t range[2050];
std::fill(std::begin(range), std::end(range), 1);
sum = parallelTransformReduce(range, 0U, std::plus<uint32_t>(), identity);
EXPECT_EQ(sum, 2050U);
std::fill(std::begin(range), std::end(range), 2);
sum = parallelTransformReduce(range, 0U, std::plus<uint32_t>(), identity);
EXPECT_EQ(sum, 4100U);
// Avoid one large task.
uint32_t range2[3060];
std::fill(std::begin(range2), std::end(range2), 1);
sum = parallelTransformReduce(range2, 0U, std::plus<uint32_t>(), identity);
EXPECT_EQ(sum, 3060U);
}
TEST(Parallel, ForEachError) {
int nums[] = {1, 2, 3, 4, 5, 6};
Error e = parallelForEachError(nums, [](int v) -> Error {
if ((v & 1) == 0)
return createStringError(std::errc::invalid_argument, "asdf");
return Error::success();
});
EXPECT_TRUE(e.isA<ErrorList>());
std::string errText = toString(std::move(e));
EXPECT_EQ(errText, std::string("asdf\nasdf\nasdf"));
}
#endif