src/cpu/o3/thread_state.hh

/*
 * Copyright (c) 2012, 2019 ARM Limited
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 *
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 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
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 * modified or unmodified, in source code or in binary form.
 *
 * Copyright (c) 2006 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
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#ifndef __CPU_O3_THREAD_STATE_HH__
#define __CPU_O3_THREAD_STATE_HH__

#include "base/callback.hh"
#include "base/compiler.hh"
#include "base/output.hh"
#include "cpu/thread_context.hh"
#include "cpu/thread_state.hh"
#include "sim/full_system.hh"
#include "sim/sim_exit.hh"

class Event;
class FunctionalMemory;
class Process;

/**
 * Class that has various thread state, such as the status, the
 * current instruction being processed, whether or not the thread has
 * a trap pending or is being externally updated, the ThreadContext
 * pointer, etc.  It also handles anything related to a specific
 * thread's process, such as syscalls and checking valid addresses.
 */
template <class Impl>
struct O3ThreadState : public ThreadState {
    typedef ThreadContext::Status Status;
    typedef typename Impl::O3CPU O3CPU;

  private:
    /** Pointer to the CPU. */
    O3CPU *cpu;

  public:
    PCEventQueue pcEventQueue;
    /**
     * An instruction-based event queue. Used for scheduling events based on
     * number of instructions committed.
     */
    EventQueue comInstEventQueue;

    /* This variable controls if writes to a thread context should cause a all
     * dynamic/speculative state to be thrown away. Nominally this is the
     * desired behavior because the external thread context write has updated
     * some state that could be used by an inflight instruction, however there
     * are some cases like in a fault/trap handler where this behavior would
     * lead to successive restarts and forward progress couldn't be made. This
     * variable controls if the squashing will occur.
     */
    bool noSquashFromTC;

    /** Whether or not the thread is currently waiting on a trap, and
     * thus able to be externally updated without squashing.
     */
    bool trapPending;

    /** Pointer to the hardware transactional memory checkpoint. */
    std::unique_ptr<BaseHTMCheckpoint> htmCheckpoint;

    O3ThreadState(O3CPU *_cpu, int _thread_num, Process *_process)
        : ThreadState(_cpu, _thread_num, _process), cpu(_cpu),
          comInstEventQueue("instruction-based event queue"),
          noSquashFromTC(false), trapPending(false), tc(nullptr)
    {
    }

    void serialize(CheckpointOut &cp) const override
    {
        ThreadState::serialize(cp);
        // Use the ThreadContext serialization helper to serialize the
        // TC.
        ::serialize(*tc, cp);
    }

    void unserialize(CheckpointIn &cp) override
    {
        // Prevent squashing - we don't have any instructions in
        // flight that we need to squash since we just instantiated a
        // clean system.
        noSquashFromTC = true;
        ThreadState::unserialize(cp);
        // Use the ThreadContext serialization helper to unserialize
        // the TC.
        ::unserialize(*tc, cp);
        noSquashFromTC = false;
    }

    /** Pointer to the ThreadContext of this thread. */
    ThreadContext *tc;

    /** Returns a pointer to the TC of this thread. */
    ThreadContext *getTC() { return tc; }

    /** Handles the syscall. */
    void syscall() { process->syscall(tc); }
};

#endif // __CPU_O3_THREAD_STATE_HH__