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110 lines
3.4 KiB
C++
110 lines
3.4 KiB
C++
// -*- mode: C++; c-file-style: "cc-mode" -*-
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//=============================================================================
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//
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// Code available from: https://verilator.org
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//
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// Copyright 2012-2024 by Wilson Snyder. This program is free software; you can
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// redistribute it and/or modify it under the terms of either the GNU
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// Lesser General Public License Version 3 or the Perl Artistic License
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// Version 2.0.
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// SPDX-License-Identifier: LGPL-3.0-only OR Artistic-2.0
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//
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//=============================================================================
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///
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/// \file
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/// \brief Verilated thread pool implementation code
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///
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/// This file must be compiled and linked against all Verilated objects
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/// that use --threads.
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///
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/// Use "verilator --threads" to add this to the Makefile for the linker.
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///
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//=============================================================================
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#include "verilatedos.h"
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#include "verilated_threads.h"
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#include <cstdio>
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#include <memory>
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#include <string>
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//=============================================================================
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// Globals
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// Internal note: Globals may multi-construct, see verilated.cpp top.
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std::atomic<uint64_t> VlMTaskVertex::s_yields;
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//=============================================================================
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// VlMTaskVertex
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VlMTaskVertex::VlMTaskVertex(uint32_t upstreamDepCount)
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: m_upstreamDepsDone{0}
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, m_upstreamDepCount{upstreamDepCount} {
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assert(atomic_is_lock_free(&m_upstreamDepsDone));
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}
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//=============================================================================
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// VlWorkerThread
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VlWorkerThread::VlWorkerThread(VerilatedContext* contextp)
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: m_ready_size{0}
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, m_cthread{startWorker, this, contextp} {}
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VlWorkerThread::~VlWorkerThread() {
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shutdown();
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// The thread should exit; join it.
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m_cthread.join();
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}
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static void shutdownTask(void*, bool) { // LCOV_EXCL_LINE
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// Deliberately empty, we use the address of this function as a magic number
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}
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void VlWorkerThread::shutdown() { addTask(shutdownTask, nullptr); }
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void VlWorkerThread::wait() {
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// Enqueue a task that sets this flag. Execution is in-order so this ensures completion.
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std::atomic<bool> flag{false};
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addTask([](void* flagp, bool) { static_cast<std::atomic<bool>*>(flagp)->store(true); }, &flag);
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// Spin wait
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for (unsigned i = 0; i < VL_LOCK_SPINS; ++i) {
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if (flag.load()) return;
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VL_CPU_RELAX();
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}
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// Yield wait
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while (!flag.load()) std::this_thread::yield();
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}
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void VlWorkerThread::workerLoop() {
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ExecRec work;
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// Wait for the first task without spinning, in case the thread is never actually used.
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dequeWork</* SpinWait: */ false>(&work);
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while (true) {
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if (VL_UNLIKELY(work.m_fnp == shutdownTask)) break;
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work.m_fnp(work.m_selfp, work.m_evenCycle);
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// Wait for next task with spinning.
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dequeWork</* SpinWait: */ true>(&work);
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}
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}
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void VlWorkerThread::startWorker(VlWorkerThread* workerp, VerilatedContext* contextp) {
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Verilated::threadContextp(contextp);
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workerp->workerLoop();
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}
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//=============================================================================
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// VlThreadPool
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VlThreadPool::VlThreadPool(VerilatedContext* contextp, unsigned nThreads) {
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for (unsigned i = 0; i < nThreads; ++i) m_workers.push_back(new VlWorkerThread{contextp});
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}
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VlThreadPool::~VlThreadPool() {
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// Each ~WorkerThread will wait for its thread to exit.
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for (auto& i : m_workers) delete i;
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}
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