gem5/cpu/simple_cpu/simple_cpu.cc

/*
 * Copyright (c) 2003 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <list>
#include <sstream>
#include <string>

#include "base/cprintf.hh"
#include "base/inifile.hh"
#include "base/loader/symtab.hh"
#include "base/misc.hh"
#include "base/pollevent.hh"
#include "base/range.hh"
#include "base/trace.hh"
#include "cpu/base_cpu.hh"
#include "cpu/exec_context.hh"
#include "cpu/exetrace.hh"
#include "cpu/full_cpu/smt.hh"
#include "cpu/simple_cpu/simple_cpu.hh"
#include "cpu/static_inst.hh"
#include "mem/base_mem.hh"
#include "mem/mem_interface.hh"
#include "sim/annotation.hh"
#include "sim/builder.hh"
#include "sim/debug.hh"
#include "sim/host.hh"
#include "sim/sim_events.hh"
#include "sim/sim_object.hh"
#include "sim/sim_stats.hh"

#ifdef FULL_SYSTEM
#include "base/remote_gdb.hh"
#include "dev/alpha_access.h"
#include "dev/pciareg.h"
#include "mem/functional_mem/memory_control.hh"
#include "mem/functional_mem/physical_memory.hh"
#include "sim/system.hh"
#include "targetarch/alpha_memory.hh"
#include "targetarch/vtophys.hh"
#else // !FULL_SYSTEM
#include "eio/eio.hh"
#include "mem/functional_mem/functional_memory.hh"
#endif // FULL_SYSTEM

using namespace std;

SimpleCPU::TickEvent::TickEvent(SimpleCPU *c)
    : Event(&mainEventQueue, CPU_Tick_Pri), cpu(c)
{
}

void
SimpleCPU::TickEvent::process()
{
    cpu->tick();
}

const char *
SimpleCPU::TickEvent::description()
{
    return "SimpleCPU tick event";
}


SimpleCPU::CacheCompletionEvent::CacheCompletionEvent(SimpleCPU *_cpu)
    : Event(&mainEventQueue),
      cpu(_cpu)
{
}

void SimpleCPU::CacheCompletionEvent::process()
{
    cpu->processCacheCompletion();
}

const char *
SimpleCPU::CacheCompletionEvent::description()
{
    return "SimpleCPU cache completion event";
}

#ifdef FULL_SYSTEM
SimpleCPU::SimpleCPU(const string &_name,
                     System *_system,
                     Counter max_insts_any_thread,
                     Counter max_insts_all_threads,
                     Counter max_loads_any_thread,
                     Counter max_loads_all_threads,
                     AlphaItb *itb, AlphaDtb *dtb,
                     FunctionalMemory *mem,
                     MemInterface *icache_interface,
                     MemInterface *dcache_interface,
                     bool _def_reg, Tick freq)
    : BaseCPU(_name, /* number_of_threads */ 1,
              max_insts_any_thread, max_insts_all_threads,
              max_loads_any_thread, max_loads_all_threads,
              _system, freq),
#else
SimpleCPU::SimpleCPU(const string &_name, Process *_process,
                     Counter max_insts_any_thread,
                     Counter max_insts_all_threads,
                     Counter max_loads_any_thread,
                     Counter max_loads_all_threads,
                     MemInterface *icache_interface,
                     MemInterface *dcache_interface,
                     bool _def_reg)
    : BaseCPU(_name, /* number_of_threads */ 1,
              max_insts_any_thread, max_insts_all_threads,
              max_loads_any_thread, max_loads_all_threads),
#endif
      tickEvent(this), xc(NULL), defer_registration(_def_reg),
      cacheCompletionEvent(this)
{
    _status = Idle;
#ifdef FULL_SYSTEM
    xc = new ExecContext(this, 0, system, itb, dtb, mem);

    // initialize CPU, including PC
    TheISA::initCPU(&xc->regs);
#else
    xc = new ExecContext(this, /* thread_num */ 0, _process, /* asid */ 0);
#endif // !FULL_SYSTEM

    icacheInterface = icache_interface;
    dcacheInterface = dcache_interface;

    memReq = new MemReq();
    memReq->xc = xc;
    memReq->asid = 0;
    memReq->data = new uint8_t[64];

    numInst = 0;
    startNumInst = 0;
    numLoad = 0;
    startNumLoad = 0;
    lastIcacheStall = 0;
    lastDcacheStall = 0;

    execContexts.push_back(xc);
}

SimpleCPU::~SimpleCPU()
{
}

void SimpleCPU::init()
{
    if (!defer_registration) {
        this->registerExecContexts();
    }
}

void
SimpleCPU::switchOut()
{
    _status = SwitchedOut;
    if (tickEvent.scheduled())
        tickEvent.squash();
}


void
SimpleCPU::takeOverFrom(BaseCPU *oldCPU)
{
    BaseCPU::takeOverFrom(oldCPU);

    assert(!tickEvent.scheduled());

    // if any of this CPU's ExecContexts are active, mark the CPU as
    // running and schedule its tick event.
    for (int i = 0; i < execContexts.size(); ++i) {
        ExecContext *xc = execContexts[i];
        if (xc->status() == ExecContext::Active && _status != Running) {
            _status = Running;
            tickEvent.schedule(curTick);
        }
    }

    oldCPU->switchOut();
}


void
SimpleCPU::activateContext(int thread_num, int delay)
{
    assert(thread_num == 0);
    assert(xc);

    assert(_status == Idle);
    notIdleFraction++;
    scheduleTickEvent(delay);
    _status = Running;
}


void
SimpleCPU::suspendContext(int thread_num)
{
    assert(thread_num == 0);
    assert(xc);

    assert(_status == Running);
    notIdleFraction--;
    unscheduleTickEvent();
    _status = Idle;
}


void
SimpleCPU::deallocateContext(int thread_num)
{
    // for now, these are equivalent
    suspendContext(thread_num);
}


void
SimpleCPU::haltContext(int thread_num)
{
    // for now, these are equivalent
    suspendContext(thread_num);
}


void
SimpleCPU::regStats()
{
    using namespace Statistics;

    BaseCPU::regStats();

    numInsts
        .name(name() + ".num_insts")
        .desc("Number of instructions executed")
        ;

    numMemRefs
        .name(name() + ".num_refs")
        .desc("Number of memory references")
        ;

    idleFraction
        .name(name() + ".idle_fraction")
        .desc("Percentage of idle cycles")
        ;

    icacheStallCycles
        .name(name() + ".icache_stall_cycles")
        .desc("ICache total stall cycles")
        .prereq(icacheStallCycles)
        ;

    dcacheStallCycles
        .name(name() + ".dcache_stall_cycles")
        .desc("DCache total stall cycles")
        .prereq(dcacheStallCycles)
        ;

    idleFraction = constant(1.0) - notIdleFraction;
    numInsts = Statistics::scalar(numInst) - Statistics::scalar(startNumInst);
    simInsts += numInsts;
}

void
SimpleCPU::resetStats()
{
    startNumInst = numInst;
    notIdleFraction = (_status != Idle);
}

void
SimpleCPU::serialize(ostream &os)
{
    SERIALIZE_ENUM(_status);
    SERIALIZE_SCALAR(inst);
    nameOut(os, csprintf("%s.xc", name()));
    xc->serialize(os);
    nameOut(os, csprintf("%s.tickEvent", name()));
    tickEvent.serialize(os);
    nameOut(os, csprintf("%s.cacheCompletionEvent", name()));
    cacheCompletionEvent.serialize(os);
}

void
SimpleCPU::unserialize(Checkpoint *cp, const string &section)
{
    UNSERIALIZE_ENUM(_status);
    UNSERIALIZE_SCALAR(inst);
    xc->unserialize(cp, csprintf("%s.xc", section));
    tickEvent.unserialize(cp, csprintf("%s.tickEvent", section));
    cacheCompletionEvent
        .unserialize(cp, csprintf("%s.cacheCompletionEvent", section));
}

void
change_thread_state(int thread_number, int activate, int priority)
{
}

// precise architected memory state accessor macros
template <class T>
Fault
SimpleCPU::read(Addr addr, T &data, unsigned flags)
{
    memReq->reset(addr, sizeof(T), flags);

    // translate to physical address
    Fault fault = xc->translateDataReadReq(memReq);

    // do functional access
    if (fault == No_Fault)
        fault = xc->read(memReq, data);

    if (traceData) {
        traceData->setAddr(addr);
        if (fault == No_Fault)
            traceData->setData(data);
    }

    // if we have a cache, do cache access too
    if (fault == No_Fault && dcacheInterface) {
        memReq->cmd = Read;
        memReq->completionEvent = NULL;
        memReq->time = curTick;
        MemAccessResult result = dcacheInterface->access(memReq);

        // Ugly hack to get an event scheduled *only* if the access is
        // a miss.  We really should add first-class support for this
        // at some point.
        if (result != MA_HIT && dcacheInterface->doEvents()) {
            memReq->completionEvent = &cacheCompletionEvent;
            lastDcacheStall = curTick;
            unscheduleTickEvent();
            _status = DcacheMissStall;
        }
    }

    return fault;
}

#ifndef DOXYGEN_SHOULD_SKIP_THIS

template
Fault
SimpleCPU::read(Addr addr, uint64_t &data, unsigned flags);

template
Fault
SimpleCPU::read(Addr addr, uint32_t &data, unsigned flags);

template
Fault
SimpleCPU::read(Addr addr, uint16_t &data, unsigned flags);

template
Fault
SimpleCPU::read(Addr addr, uint8_t &data, unsigned flags);

#endif //DOXYGEN_SHOULD_SKIP_THIS

template<>
Fault
SimpleCPU::read(Addr addr, double &data, unsigned flags)
{
    return read(addr, *(uint64_t*)&data, flags);
}

template<>
Fault
SimpleCPU::read(Addr addr, float &data, unsigned flags)
{
    return read(addr, *(uint32_t*)&data, flags);
}


template<>
Fault
SimpleCPU::read(Addr addr, int32_t &data, unsigned flags)
{
    return read(addr, (uint32_t&)data, flags);
}


template <class T>
Fault
SimpleCPU::write(T data, Addr addr, unsigned flags, uint64_t *res)
{
    if (traceData) {
        traceData->setAddr(addr);
        traceData->setData(data);
    }

    memReq->reset(addr, sizeof(T), flags);

    // translate to physical address
    Fault fault = xc->translateDataWriteReq(memReq);

    // do functional access
    if (fault == No_Fault)
        fault = xc->write(memReq, data);

    if (fault == No_Fault && dcacheInterface) {
        memReq->cmd = Write;
        memcpy(memReq->data,(uint8_t *)&data,memReq->size);
        memReq->completionEvent = NULL;
        memReq->time = curTick;
        MemAccessResult result = dcacheInterface->access(memReq);

        // Ugly hack to get an event scheduled *only* if the access is
        // a miss.  We really should add first-class support for this
        // at some point.
        if (result != MA_HIT && dcacheInterface->doEvents()) {
            memReq->completionEvent = &cacheCompletionEvent;
            lastDcacheStall = curTick;
            unscheduleTickEvent();
            _status = DcacheMissStall;
        }
    }

    if (res && (fault == No_Fault))
        *res = memReq->result;

    return fault;
}


#ifndef DOXYGEN_SHOULD_SKIP_THIS
template
Fault
SimpleCPU::write(uint64_t data, Addr addr, unsigned flags, uint64_t *res);

template
Fault
SimpleCPU::write(uint32_t data, Addr addr, unsigned flags, uint64_t *res);

template
Fault
SimpleCPU::write(uint16_t data, Addr addr, unsigned flags, uint64_t *res);

template
Fault
SimpleCPU::write(uint8_t data, Addr addr, unsigned flags, uint64_t *res);

#endif //DOXYGEN_SHOULD_SKIP_THIS

template<>
Fault
SimpleCPU::write(double data, Addr addr, unsigned flags, uint64_t *res)
{
    return write(*(uint64_t*)&data, addr, flags, res);
}

template<>
Fault
SimpleCPU::write(float data, Addr addr, unsigned flags, uint64_t *res)
{
    return write(*(uint32_t*)&data, addr, flags, res);
}


template<>
Fault
SimpleCPU::write(int32_t data, Addr addr, unsigned flags, uint64_t *res)
{
    return write((uint32_t)data, addr, flags, res);
}


#ifdef FULL_SYSTEM
Addr
SimpleCPU::dbg_vtophys(Addr addr)
{
    return vtophys(xc, addr);
}
#endif // FULL_SYSTEM

Tick save_cycle = 0;


void
SimpleCPU::processCacheCompletion()
{
    switch (status()) {
      case IcacheMissStall:
        icacheStallCycles += curTick - lastIcacheStall;
        _status = IcacheMissComplete;
        scheduleTickEvent(1);
        break;
      case DcacheMissStall:
        dcacheStallCycles += curTick - lastDcacheStall;
        _status = Running;
        scheduleTickEvent(1);
        break;
      case SwitchedOut:
        // If this CPU has been switched out due to sampling/warm-up,
        // ignore any further status changes (e.g., due to cache
        // misses outstanding at the time of the switch).
        return;
      default:
        panic("SimpleCPU::processCacheCompletion: bad state");
        break;
    }
}

#ifdef FULL_SYSTEM
void
SimpleCPU::post_interrupt(int int_num, int index)
{
    BaseCPU::post_interrupt(int_num, index);

    if (xc->status() == ExecContext::Suspended) {
                DPRINTF(IPI,"Suspended Processor awoke\n");
        xc->activate();
        Annotate::Resume(xc);
    }
}
#endif // FULL_SYSTEM

/* start simulation, program loaded, processor precise state initialized */
void
SimpleCPU::tick()
{
    traceData = NULL;

    Fault fault = No_Fault;

#ifdef FULL_SYSTEM
    if (AlphaISA::check_interrupts &&
        xc->cpu->check_interrupts() &&
        !PC_PAL(xc->regs.pc) &&
        status() != IcacheMissComplete) {
        int ipl = 0;
        int summary = 0;
        AlphaISA::check_interrupts = 0;
        IntReg *ipr = xc->regs.ipr;

        if (xc->regs.ipr[TheISA::IPR_SIRR]) {
            for (int i = TheISA::INTLEVEL_SOFTWARE_MIN;
                 i < TheISA::INTLEVEL_SOFTWARE_MAX; i++) {
                if (ipr[TheISA::IPR_SIRR] & (ULL(1) << i)) {
                    // See table 4-19 of 21164 hardware reference
                    ipl = (i - TheISA::INTLEVEL_SOFTWARE_MIN) + 1;
                    summary |= (ULL(1) << i);
                }
            }
        }

        uint64_t interrupts = xc->cpu->intr_status();
        for (int i = TheISA::INTLEVEL_EXTERNAL_MIN;
            i < TheISA::INTLEVEL_EXTERNAL_MAX; i++) {
            if (interrupts & (ULL(1) << i)) {
                // See table 4-19 of 21164 hardware reference
                ipl = i;
                summary |= (ULL(1) << i);
            }
        }

        if (ipr[TheISA::IPR_ASTRR])
            panic("asynchronous traps not implemented\n");

        if (ipl && ipl > xc->regs.ipr[TheISA::IPR_IPLR]) {
            ipr[TheISA::IPR_ISR] = summary;
            ipr[TheISA::IPR_INTID] = ipl;
            xc->ev5_trap(Interrupt_Fault);

            DPRINTF(Flow, "Interrupt! IPLR=%d ipl=%d summary=%x\n",
                    ipr[TheISA::IPR_IPLR], ipl, summary);
        }
    }
#endif

    // maintain $r0 semantics
    xc->regs.intRegFile[ZeroReg] = 0;
#ifdef TARGET_ALPHA
    xc->regs.floatRegFile.d[ZeroReg] = 0.0;
#endif // TARGET_ALPHA

    if (status() == IcacheMissComplete) {
        // We've already fetched an instruction and were stalled on an
        // I-cache miss.  No need to fetch it again.

        // Set status to running; tick event will get rescheduled if
        // necessary at end of tick() function.
        _status = Running;
    }
    else {
        // Try to fetch an instruction

        // set up memory request for instruction fetch
#ifdef FULL_SYSTEM
#define IFETCH_FLAGS(pc)	((pc) & 1) ? PHYSICAL : 0
#else
#define IFETCH_FLAGS(pc)	0
#endif

        memReq->cmd = Read;
        memReq->reset(xc->regs.pc & ~3, sizeof(uint32_t),
                     IFETCH_FLAGS(xc->regs.pc));

        fault = xc->translateInstReq(memReq);

        if (fault == No_Fault)
            fault = xc->mem->read(memReq, inst);

        if (icacheInterface && fault == No_Fault) {
            memReq->completionEvent = NULL;

            memReq->time = curTick;
            MemAccessResult result = icacheInterface->access(memReq);

            // Ugly hack to get an event scheduled *only* if the access is
            // a miss.  We really should add first-class support for this
            // at some point.
            if (result != MA_HIT && icacheInterface->doEvents()) {
                memReq->completionEvent = &cacheCompletionEvent;
                lastIcacheStall = curTick;
                unscheduleTickEvent();
                _status = IcacheMissStall;
                return;
            }
        }
    }

    // If we've got a valid instruction (i.e., no fault on instruction
    // fetch), then execute it.
    if (fault == No_Fault) {

        // keep an instruction count
        numInst++;

        // check for instruction-count-based events
        comInstEventQueue[0]->serviceEvents(numInst);

        // decode the instruction
        StaticInstPtr<TheISA> si(inst);

        traceData = Trace::getInstRecord(curTick, xc, this, si,
                                         xc->regs.pc);

#ifdef FULL_SYSTEM
        xc->regs.opcode = (inst >> 26) & 0x3f;
        xc->regs.ra = (inst >> 21) & 0x1f;
#endif // FULL_SYSTEM

        xc->func_exe_inst++;

        fault = si->execute(this, xc, traceData);
#ifdef FS_MEASURE
        if (!(xc->misspeculating()) && (xc->system->bin)) {
            SWContext *ctx = xc->swCtx;
            if (ctx && !ctx->callStack.empty()) {
                if (si->isCall()) {
                    ctx->calls++;
                }
                if (si->isReturn()) {
                     if (ctx->calls == 0) {
                        fnCall *top = ctx->callStack.top();
                        DPRINTF(TCPIP, "Removing %s from callstack.\n", top->name);
                        delete top;
                        ctx->callStack.pop();
                        if (ctx->callStack.empty())
                            xc->system->nonPath->activate();
                        else
                            ctx->callStack.top()->myBin->activate();

                        xc->system->dumpState(xc);
                    } else {
                        ctx->calls--;
                    }
                }
            }
        }
#endif
        if (si->isMemRef()) {
            numMemRefs++;
        }

        if (si->isLoad()) {
            ++numLoad;
            comLoadEventQueue[0]->serviceEvents(numLoad);
        }

        if (traceData)
            traceData->finalize();

    }	// if (fault == No_Fault)

    if (fault != No_Fault) {
#ifdef FULL_SYSTEM
        xc->ev5_trap(fault);
#else // !FULL_SYSTEM
        fatal("fault (%d) detected @ PC 0x%08p", fault, xc->regs.pc);
#endif // FULL_SYSTEM
    }
    else {
        // go to the next instruction
        xc->regs.pc = xc->regs.npc;
        xc->regs.npc += sizeof(MachInst);
    }

#ifdef FULL_SYSTEM
    Addr oldpc;
    do {
        oldpc = xc->regs.pc;
        system->pcEventQueue.service(xc);
    } while (oldpc != xc->regs.pc);
#endif

    assert(status() == Running ||
           status() == Idle ||
           status() == DcacheMissStall);

    if (status() == Running && !tickEvent.scheduled())
        tickEvent.schedule(curTick + 1);
}


////////////////////////////////////////////////////////////////////////
//
//  SimpleCPU Simulation Object
//
BEGIN_DECLARE_SIM_OBJECT_PARAMS(SimpleCPU)

    Param<Counter> max_insts_any_thread;
    Param<Counter> max_insts_all_threads;
    Param<Counter> max_loads_any_thread;
    Param<Counter> max_loads_all_threads;

#ifdef FULL_SYSTEM
    SimObjectParam<AlphaItb *> itb;
    SimObjectParam<AlphaDtb *> dtb;
    SimObjectParam<FunctionalMemory *> mem;
    SimObjectParam<System *> system;
    Param<int> mult;
#else
    SimObjectParam<Process *> workload;
#endif // FULL_SYSTEM

    SimObjectParam<BaseMem *> icache;
    SimObjectParam<BaseMem *> dcache;

    Param<bool> defer_registration;

END_DECLARE_SIM_OBJECT_PARAMS(SimpleCPU)

BEGIN_INIT_SIM_OBJECT_PARAMS(SimpleCPU)

    INIT_PARAM_DFLT(max_insts_any_thread,
                    "terminate when any thread reaches this inst count",
                    0),
    INIT_PARAM_DFLT(max_insts_all_threads,
                    "terminate when all threads have reached this inst count",
                    0),
    INIT_PARAM_DFLT(max_loads_any_thread,
                    "terminate when any thread reaches this load count",
                    0),
    INIT_PARAM_DFLT(max_loads_all_threads,
                    "terminate when all threads have reached this load count",
                    0),

#ifdef FULL_SYSTEM
    INIT_PARAM(itb, "Instruction TLB"),
    INIT_PARAM(dtb, "Data TLB"),
    INIT_PARAM(mem, "memory"),
    INIT_PARAM(system, "system object"),
    INIT_PARAM_DFLT(mult, "system clock multiplier", 1),
#else
    INIT_PARAM(workload, "processes to run"),
#endif // FULL_SYSTEM

    INIT_PARAM_DFLT(icache, "L1 instruction cache object", NULL),
    INIT_PARAM_DFLT(dcache, "L1 data cache object", NULL),
    INIT_PARAM_DFLT(defer_registration, "defer registration with system "
                    "(for sampling)", false)

END_INIT_SIM_OBJECT_PARAMS(SimpleCPU)


CREATE_SIM_OBJECT(SimpleCPU)
{
    SimpleCPU *cpu;
#ifdef FULL_SYSTEM
    if (mult != 1)
        panic("processor clock multiplier must be 1\n");

    cpu = new SimpleCPU(getInstanceName(), system,
                        max_insts_any_thread, max_insts_all_threads,
                        max_loads_any_thread, max_loads_all_threads,
                        itb, dtb, mem,
                        (icache) ? icache->getInterface() : NULL,
                        (dcache) ? dcache->getInterface() : NULL,
                        defer_registration,
                        ticksPerSecond * mult);
#else

    cpu = new SimpleCPU(getInstanceName(), workload,
                        max_insts_any_thread, max_insts_all_threads,
                        max_loads_any_thread, max_loads_all_threads,
                        (icache) ? icache->getInterface() : NULL,
                        (dcache) ? dcache->getInterface() : NULL,
                        defer_registration);

#endif // FULL_SYSTEM
#if 0
    if (!defer_registration) {
        cpu->registerExecContexts();
    }
#endif
    return cpu;
}

REGISTER_SIM_OBJECT("SimpleCPU", SimpleCPU)