1 //===-- Benchmark memory specific tools -----------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "LibcMemoryBenchmark.h" 10 #include "llvm/ADT/SmallVector.h" 11 #include "llvm/Support/ErrorHandling.h" 12 #include "llvm/Support/MathExtras.h" 13 #include <algorithm> 14 15 namespace llvm { 16 namespace libc_benchmarks { 17 18 // Returns a distribution that samples the buffer to satisfy the required 19 // alignment. 20 // When alignment is set, the distribution is scaled down by `Factor` and scaled 21 // up again by the same amount during sampling. 22 static std::uniform_int_distribution<uint32_t> GetOffsetDistribution(const StudyConfiguration & Conf)23GetOffsetDistribution(const StudyConfiguration &Conf) { 24 if (Conf.AddressAlignment && 25 *Conf.AddressAlignment > AlignedBuffer::Alignment) 26 report_fatal_error( 27 "AddressAlignment must be less or equal to AlignedBuffer::Alignment"); 28 if (!Conf.AddressAlignment) 29 return std::uniform_int_distribution<uint32_t>(0, 0); // Always 0. 30 // If we test up to Size bytes, the returned offset must stay under 31 // BuffersSize - Size. 32 int64_t MaxOffset = Conf.BufferSize; 33 MaxOffset -= Conf.Size.To; 34 MaxOffset -= 1; 35 if (MaxOffset < 0) 36 report_fatal_error( 37 "BufferSize too small to exercise specified Size configuration"); 38 MaxOffset /= Conf.AddressAlignment->value(); 39 return std::uniform_int_distribution<uint32_t>(0, MaxOffset); 40 } 41 OffsetDistribution(const StudyConfiguration & Conf)42OffsetDistribution::OffsetDistribution(const StudyConfiguration &Conf) 43 : Distribution(GetOffsetDistribution(Conf)), 44 Factor(Conf.AddressAlignment.valueOrOne().value()) {} 45 46 // Precomputes offset where to insert mismatches between the two buffers. MismatchOffsetDistribution(const StudyConfiguration & Conf)47MismatchOffsetDistribution::MismatchOffsetDistribution( 48 const StudyConfiguration &Conf) 49 : MismatchAt(Conf.MemcmpMismatchAt) { 50 if (MismatchAt <= 1) 51 return; 52 const auto ToSize = Conf.Size.To; 53 for (size_t I = ToSize + 1; I < Conf.BufferSize; I += ToSize) 54 MismatchIndices.push_back(I); 55 if (MismatchIndices.empty()) 56 llvm::report_fatal_error("Unable to generate mismatch"); 57 MismatchIndexSelector = 58 std::uniform_int_distribution<size_t>(0, MismatchIndices.size() - 1); 59 } 60 61 } // namespace libc_benchmarks 62 } // namespace llvm 63