src/cpu/simple/base.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2010-2012, 2015, 2017, 2018, 2020 ARM Limited
  * Copyright (c) 2013 Advanced Micro Devices, Inc.
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
  * not be construed as granting a license to any other intellectual
  * 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
  * unmodified and in its entirety in all distributions of the software,
  * modified or unmodified, in source code or in binary form.
  *
  * Copyright (c) 2002-2005 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 "cpu/simple/base.hh"

 #include "arch/utility.hh"
 #include "base/cprintf.hh"
 #include "base/inifile.hh"
 #include "base/loader/symtab.hh"
 #include "base/logging.hh"
 #include "base/pollevent.hh"
 #include "base/trace.hh"
 #include "base/types.hh"
 #include "config/the_isa.hh"
 #include "cpu/base.hh"
 #include "cpu/checker/cpu.hh"
 #include "cpu/checker/thread_context.hh"
 #include "cpu/exetrace.hh"
 #include "cpu/pred/bpred_unit.hh"
 #include "cpu/simple/exec_context.hh"
 #include "cpu/simple_thread.hh"
 #include "cpu/smt.hh"
 #include "cpu/static_inst.hh"
 #include "cpu/thread_context.hh"
 #include "debug/Decode.hh"
 #include "debug/ExecFaulting.hh"
 #include "debug/Fetch.hh"
 #include "debug/HtmCpu.hh"
 #include "debug/Quiesce.hh"
 #include "mem/packet.hh"
 #include "mem/request.hh"
 #include "params/BaseSimpleCPU.hh"
 #include "sim/byteswap.hh"
 #include "sim/debug.hh"
 #include "sim/faults.hh"
 #include "sim/full_system.hh"
 #include "sim/sim_events.hh"
 #include "sim/sim_object.hh"
 #include "sim/stats.hh"
 #include "sim/system.hh"

 BaseSimpleCPU::BaseSimpleCPU(const BaseSimpleCPUParams &p)
     : BaseCPU(p),
       curThread(0),
       branchPred(p.branchPred),
       traceData(NULL),
       inst(),
       _status(Idle)
 {
     SimpleThread *thread;

     for (unsigned i = 0; i < numThreads; i++) {
         if (FullSystem) {
             thread = new SimpleThread(
                 this, i, p.system, p.mmu, p.isa[i]);
         } else {
             thread = new SimpleThread(
                 this, i, p.system, p.workload[i], p.mmu, p.isa[i]);
         }
         threadInfo.push_back(new SimpleExecContext(this, thread));
         ThreadContext *tc = thread->getTC();
         threadContexts.push_back(tc);
     }

     if (p.checker) {
         if (numThreads != 1)
             fatal("Checker currently does not support SMT");

         BaseCPU *temp_checker = p.checker;
         checker = dynamic_cast<CheckerCPU *>(temp_checker);
         checker->setSystem(p.system);
         // Manipulate thread context
         ThreadContext *cpu_tc = threadContexts[0];
         threadContexts[0] = new CheckerThreadContext<ThreadContext>(cpu_tc, this->checker);
     } else {
         checker = NULL;
     }
 }

 void
 BaseSimpleCPU::init()
 {
     BaseCPU::init();

     for (auto tc : threadContexts) {
         // Initialise the ThreadContext's memory proxies
         tc->initMemProxies(tc);
     }
 }

 void
 BaseSimpleCPU::checkPcEventQueue()
 {
     Addr oldpc, pc = threadInfo[curThread]->thread->instAddr();
     do {
         oldpc = pc;
         threadInfo[curThread]->thread->pcEventQueue.service(
                 oldpc, threadContexts[curThread]);
         pc = threadInfo[curThread]->thread->instAddr();
     } while (oldpc != pc);
 }

 void
 BaseSimpleCPU::swapActiveThread()
 {
     if (numThreads > 1) {
         if ((!curStaticInst || !curStaticInst->isDelayedCommit()) &&
              !threadInfo[curThread]->stayAtPC) {
             // Swap active threads
             if (!activeThreads.empty()) {
                 curThread = activeThreads.front();
                 activeThreads.pop_front();
                 activeThreads.push_back(curThread);
             }
         }
     }
 }

 void
 BaseSimpleCPU::countInst()
 {
     SimpleExecContext& t_info = *threadInfo[curThread];

     if (!curStaticInst->isMicroop() || curStaticInst->isLastMicroop()) {
         t_info.numInst++;
         t_info.execContextStats.numInsts++;

         t_info.thread->funcExeInst++;
     }
     t_info.numOp++;
     t_info.execContextStats.numOps++;
 }

 Counter
 BaseSimpleCPU::totalInsts() const
 {
     Counter total_inst = 0;
     for (auto& t_info : threadInfo) {
         total_inst += t_info->numInst;
     }

     return total_inst;
 }

 Counter
 BaseSimpleCPU::totalOps() const
 {
     Counter total_op = 0;
     for (auto& t_info : threadInfo) {
         total_op += t_info->numOp;
     }

     return total_op;
 }

 BaseSimpleCPU::~BaseSimpleCPU()
 {
 }

 void
 BaseSimpleCPU::haltContext(ThreadID thread_num)
 {
     // for now, these are equivalent
     suspendContext(thread_num);
     updateCycleCounters(BaseCPU::CPU_STATE_SLEEP);
 }

 void
 BaseSimpleCPU::resetStats()
 {
     BaseCPU::resetStats();
     for (auto &thread_info : threadInfo) {
         thread_info->execContextStats.notIdleFraction = (_status != Idle);
     }
 }

 void
 BaseSimpleCPU::serializeThread(CheckpointOut &cp, ThreadID tid) const
 {
     assert(_status == Idle || _status == Running);

     threadInfo[tid]->thread->serialize(cp);
 }

 void
 BaseSimpleCPU::unserializeThread(CheckpointIn &cp, ThreadID tid)
 {
     threadInfo[tid]->thread->unserialize(cp);
 }

 void
 change_thread_state(ThreadID tid, int activate, int priority)
 {
 }

 void
 BaseSimpleCPU::wakeup(ThreadID tid)
 {
     getCpuAddrMonitor(tid)->gotWakeup = true;

     if (threadInfo[tid]->thread->status() == ThreadContext::Suspended) {
         DPRINTF(Quiesce,"[tid:%d] Suspended Processor awoke\n", tid);
         threadInfo[tid]->thread->activate();
     }
 }

 void
 BaseSimpleCPU::traceFault()
 {
     if (DTRACE(ExecFaulting)) {
         traceData->setFaulting(true);
     } else {
         delete traceData;
         traceData = NULL;
     }
 }

 void
 BaseSimpleCPU::checkForInterrupts()
 {
     SimpleExecContext&t_info = *threadInfo[curThread];
     SimpleThread* thread = t_info.thread;
     ThreadContext* tc = thread->getTC();

     if (checkInterrupts(curThread)) {
         Fault interrupt = interrupts[curThread]->getInterrupt();

         if (interrupt != NoFault) {
             // hardware transactional memory
             // Postpone taking interrupts while executing transactions.
             assert(!std::dynamic_pointer_cast<GenericHtmFailureFault>(
                 interrupt));
             if (t_info.inHtmTransactionalState()) {
                 DPRINTF(HtmCpu, "Deferring pending interrupt - %s -"
                     "due to transactional state\n",
                     interrupt->name());
                 return;
             }

             t_info.fetchOffset = 0;
             interrupts[curThread]->updateIntrInfo();
             interrupt->invoke(tc);
             thread->decoder.reset();
         }
     }
 }


 void
 BaseSimpleCPU::setupFetchRequest(const RequestPtr &req)
 {
     SimpleExecContext &t_info = *threadInfo[curThread];
     SimpleThread* thread = t_info.thread;

     Addr instAddr = thread->instAddr();
     Addr fetchPC = (instAddr & PCMask) + t_info.fetchOffset;

     // set up memory request for instruction fetch
     DPRINTF(Fetch, "Fetch: Inst PC:%08p, Fetch PC:%08p\n", instAddr, fetchPC);

     req->setVirt(fetchPC, sizeof(TheISA::MachInst), Request::INST_FETCH,
                  instRequestorId(), instAddr);
 }


 void
 BaseSimpleCPU::preExecute()
 {
     SimpleExecContext &t_info = *threadInfo[curThread];
     SimpleThread* thread = t_info.thread;

     // maintain $r0 semantics
     thread->setIntReg(TheISA::ZeroReg, 0);

     // resets predicates
     t_info.setPredicate(true);
     t_info.setMemAccPredicate(true);

     // check for instruction-count-based events
     thread->comInstEventQueue.serviceEvents(t_info.numInst);

     // decode the instruction
     TheISA::PCState pcState = thread->pcState();

     if (isRomMicroPC(pcState.microPC())) {
         t_info.stayAtPC = false;
         curStaticInst = thread->decoder.fetchRomMicroop(
                 pcState.microPC(), curMacroStaticInst);
     } else if (!curMacroStaticInst) {
         //We're not in the middle of a macro instruction
         StaticInstPtr instPtr = NULL;

         TheISA::Decoder *decoder = &(thread->decoder);

         //Predecode, ie bundle up an ExtMachInst
         //If more fetch data is needed, pass it in.
         Addr fetchPC = (pcState.instAddr() & PCMask) + t_info.fetchOffset;
         //if (decoder->needMoreBytes())
             decoder->moreBytes(pcState, fetchPC, inst);
         //else
         //    decoder->process();

         //Decode an instruction if one is ready. Otherwise, we'll have to
         //fetch beyond the MachInst at the current pc.
         instPtr = decoder->decode(pcState);
         if (instPtr) {
             t_info.stayAtPC = false;
             thread->pcState(pcState);
         } else {
             t_info.stayAtPC = true;
             t_info.fetchOffset += sizeof(TheISA::MachInst);
         }

         //If we decoded an instruction and it's microcoded, start pulling
         //out micro ops
         if (instPtr && instPtr->isMacroop()) {
             curMacroStaticInst = instPtr;
             curStaticInst =
                 curMacroStaticInst->fetchMicroop(pcState.microPC());
         } else {
             curStaticInst = instPtr;
         }
     } else {
         //Read the next micro op from the macro op
         curStaticInst = curMacroStaticInst->fetchMicroop(pcState.microPC());
     }

     //If we decoded an instruction this "tick", record information about it.
     if (curStaticInst) {
 #if TRACING_ON
         traceData = tracer->getInstRecord(curTick(), thread->getTC(),
                 curStaticInst, thread->pcState(), curMacroStaticInst);
 #endif // TRACING_ON
     }

     if (branchPred && curStaticInst &&
         curStaticInst->isControl()) {
         // Use a fake sequence number since we only have one
         // instruction in flight at the same time.
         const InstSeqNum cur_sn(0);
         t_info.predPC = thread->pcState();
         const bool predict_taken(
             branchPred->predict(curStaticInst, cur_sn, t_info.predPC,
                                 curThread));

         if (predict_taken)
             ++t_info.execContextStats.numPredictedBranches;
     }
 }

 void
 BaseSimpleCPU::postExecute()
 {
     SimpleExecContext &t_info = *threadInfo[curThread];

     assert(curStaticInst);

     TheISA::PCState pc = threadContexts[curThread]->pcState();
     Addr instAddr = pc.instAddr();

     if (curStaticInst->isMemRef()) {
         t_info.execContextStats.numMemRefs++;
     }

     if (curStaticInst->isLoad()) {
         ++t_info.numLoad;
     }

     if (curStaticInst->isControl()) {
         ++t_info.execContextStats.numBranches;
     }

     /* Power model statistics */
     //integer alu accesses
     if (curStaticInst->isInteger()){
         t_info.execContextStats.numIntAluAccesses++;
         t_info.execContextStats.numIntInsts++;
     }

     //float alu accesses
     if (curStaticInst->isFloating()){
         t_info.execContextStats.numFpAluAccesses++;
         t_info.execContextStats.numFpInsts++;
     }

     //vector alu accesses
     if (curStaticInst->isVector()){
         t_info.execContextStats.numVecAluAccesses++;
         t_info.execContextStats.numVecInsts++;
     }

     //number of function calls/returns to get window accesses
     if (curStaticInst->isCall() || curStaticInst->isReturn()){
         t_info.execContextStats.numCallsReturns++;
     }

     //the number of branch predictions that will be made
     if (curStaticInst->isCondCtrl()){
         t_info.execContextStats.numCondCtrlInsts++;
     }

     //result bus acceses
     if (curStaticInst->isLoad()){
         t_info.execContextStats.numLoadInsts++;
     }

     if (curStaticInst->isStore() || curStaticInst->isAtomic()){
         t_info.execContextStats.numStoreInsts++;
     }
     /* End power model statistics */

     t_info.execContextStats.statExecutedInstType[curStaticInst->opClass()]++;

     if (FullSystem)
         traceFunctions(instAddr);

     if (traceData) {
         traceData->dump();
         delete traceData;
         traceData = NULL;
     }

     // Call CPU instruction commit probes
     probeInstCommit(curStaticInst, instAddr);
 }

 void
 BaseSimpleCPU::advancePC(const Fault &fault)
 {
     SimpleExecContext &t_info = *threadInfo[curThread];
     SimpleThread* thread = t_info.thread;

     const bool branching(thread->pcState().branching());

     //Since we're moving to a new pc, zero out the offset
     t_info.fetchOffset = 0;
     if (fault != NoFault) {
         curMacroStaticInst = StaticInst::nullStaticInstPtr;
         fault->invoke(threadContexts[curThread], curStaticInst);
         thread->decoder.reset();
     } else {
         if (curStaticInst) {
             if (curStaticInst->isLastMicroop())
                 curMacroStaticInst = StaticInst::nullStaticInstPtr;
             TheISA::PCState pcState = thread->pcState();
             TheISA::advancePC(pcState, curStaticInst);
             thread->pcState(pcState);
         }
     }

     if (branchPred && curStaticInst && curStaticInst->isControl()) {
         // Use a fake sequence number since we only have one
         // instruction in flight at the same time.
         const InstSeqNum cur_sn(0);

         if (t_info.predPC == thread->pcState()) {
             // Correctly predicted branch
             branchPred->update(cur_sn, curThread);
         } else {
             // Mis-predicted branch
             branchPred->squash(cur_sn, thread->pcState(), branching, curThread);
             ++t_info.execContextStats.numBranchMispred;
         }
     }
 }
	/*
	* Copyright (c) 2010-2012, 2015, 2017, 2018, 2020 ARM Limited
	* Copyright (c) 2013 Advanced Micro Devices, Inc.
	* All rights reserved
	*
	* The license below extends only to copyright in the software and shall
	* not be construed as granting a license to any other intellectual
	* 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
	* unmodified and in its entirety in all distributions of the software,
	* modified or unmodified, in source code or in binary form.
	*
	* Copyright (c) 2002-2005 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 "cpu/simple/base.hh"

	#include "arch/utility.hh"
	#include "base/cprintf.hh"
	#include "base/inifile.hh"
	#include "base/loader/symtab.hh"
	#include "base/logging.hh"
	#include "base/pollevent.hh"
	#include "base/trace.hh"
	#include "base/types.hh"
	#include "config/the_isa.hh"
	#include "cpu/base.hh"
	#include "cpu/checker/cpu.hh"
	#include "cpu/checker/thread_context.hh"
	#include "cpu/exetrace.hh"
	#include "cpu/pred/bpred_unit.hh"
	#include "cpu/simple/exec_context.hh"
	#include "cpu/simple_thread.hh"
	#include "cpu/smt.hh"
	#include "cpu/static_inst.hh"
	#include "cpu/thread_context.hh"
	#include "debug/Decode.hh"
	#include "debug/ExecFaulting.hh"
	#include "debug/Fetch.hh"
	#include "debug/HtmCpu.hh"
	#include "debug/Quiesce.hh"
	#include "mem/packet.hh"
	#include "mem/request.hh"
	#include "params/BaseSimpleCPU.hh"
	#include "sim/byteswap.hh"
	#include "sim/debug.hh"
	#include "sim/faults.hh"
	#include "sim/full_system.hh"
	#include "sim/sim_events.hh"
	#include "sim/sim_object.hh"
	#include "sim/stats.hh"
	#include "sim/system.hh"

	BaseSimpleCPU::BaseSimpleCPU(const BaseSimpleCPUParams &p)
	: BaseCPU(p),
	curThread(0),
	branchPred(p.branchPred),
	traceData(NULL),
	inst(),
	_status(Idle)
	{
	SimpleThread *thread;

	for (unsigned i = 0; i < numThreads; i++) {
	if (FullSystem) {
	thread = new SimpleThread(
	this, i, p.system, p.mmu, p.isa[i]);
	} else {
	thread = new SimpleThread(
	this, i, p.system, p.workload[i], p.mmu, p.isa[i]);
	}
	threadInfo.push_back(new SimpleExecContext(this, thread));
	ThreadContext *tc = thread->getTC();
	threadContexts.push_back(tc);
	}

	if (p.checker) {
	if (numThreads != 1)
	fatal("Checker currently does not support SMT");

	BaseCPU *temp_checker = p.checker;
	checker = dynamic_cast<CheckerCPU *>(temp_checker);
	checker->setSystem(p.system);
	// Manipulate thread context
	ThreadContext *cpu_tc = threadContexts[0];
	threadContexts[0] = new CheckerThreadContext<ThreadContext>(cpu_tc, this->checker);
	} else {
	checker = NULL;
	}
	}

	void
	BaseSimpleCPU::init()
	{
	BaseCPU::init();

	for (auto tc : threadContexts) {
	// Initialise the ThreadContext's memory proxies
	tc->initMemProxies(tc);
	}
	}

	void
	BaseSimpleCPU::checkPcEventQueue()
	{
	Addr oldpc, pc = threadInfo[curThread]->thread->instAddr();
	do {
	oldpc = pc;
	threadInfo[curThread]->thread->pcEventQueue.service(
	oldpc, threadContexts[curThread]);
	pc = threadInfo[curThread]->thread->instAddr();
	} while (oldpc != pc);
	}

	void
	BaseSimpleCPU::swapActiveThread()
	{
	if (numThreads > 1) {
	if ((!curStaticInst \|\| !curStaticInst->isDelayedCommit()) &&
	!threadInfo[curThread]->stayAtPC) {
	// Swap active threads
	if (!activeThreads.empty()) {
	curThread = activeThreads.front();
	activeThreads.pop_front();
	activeThreads.push_back(curThread);
	}
	}
	}
	}

	void
	BaseSimpleCPU::countInst()
	{
	SimpleExecContext& t_info = *threadInfo[curThread];

	if (!curStaticInst->isMicroop() \|\| curStaticInst->isLastMicroop()) {
	t_info.numInst++;
	t_info.execContextStats.numInsts++;

	t_info.thread->funcExeInst++;
	}
	t_info.numOp++;
	t_info.execContextStats.numOps++;
	}

	Counter
	BaseSimpleCPU::totalInsts() const
	{
	Counter total_inst = 0;
	for (auto& t_info : threadInfo) {
	total_inst += t_info->numInst;
	}

	return total_inst;
	}

	Counter
	BaseSimpleCPU::totalOps() const
	{
	Counter total_op = 0;
	for (auto& t_info : threadInfo) {
	total_op += t_info->numOp;
	}

	return total_op;
	}

	BaseSimpleCPU::~BaseSimpleCPU()
	{
	}

	void
	BaseSimpleCPU::haltContext(ThreadID thread_num)
	{
	// for now, these are equivalent
	suspendContext(thread_num);
	updateCycleCounters(BaseCPU::CPU_STATE_SLEEP);
	}

	void
	BaseSimpleCPU::resetStats()
	{
	BaseCPU::resetStats();
	for (auto &thread_info : threadInfo) {
	thread_info->execContextStats.notIdleFraction = (_status != Idle);
	}
	}

	void
	BaseSimpleCPU::serializeThread(CheckpointOut &cp, ThreadID tid) const
	{
	assert(_status == Idle \|\| _status == Running);

	threadInfo[tid]->thread->serialize(cp);
	}

	void
	BaseSimpleCPU::unserializeThread(CheckpointIn &cp, ThreadID tid)
	{
	threadInfo[tid]->thread->unserialize(cp);
	}

	void
	change_thread_state(ThreadID tid, int activate, int priority)
	{
	}

	void
	BaseSimpleCPU::wakeup(ThreadID tid)
	{
	getCpuAddrMonitor(tid)->gotWakeup = true;

	if (threadInfo[tid]->thread->status() == ThreadContext::Suspended) {
	DPRINTF(Quiesce,"[tid:%d] Suspended Processor awoke\n", tid);
	threadInfo[tid]->thread->activate();
	}
	}

	void
	BaseSimpleCPU::traceFault()
	{
	if (DTRACE(ExecFaulting)) {
	traceData->setFaulting(true);
	} else {
	delete traceData;
	traceData = NULL;
	}
	}

	void
	BaseSimpleCPU::checkForInterrupts()
	{
	SimpleExecContext&t_info = *threadInfo[curThread];
	SimpleThread* thread = t_info.thread;
	ThreadContext* tc = thread->getTC();

	if (checkInterrupts(curThread)) {
	Fault interrupt = interrupts[curThread]->getInterrupt();

	if (interrupt != NoFault) {
	// hardware transactional memory
	// Postpone taking interrupts while executing transactions.
	assert(!std::dynamic_pointer_cast<GenericHtmFailureFault>(
	interrupt));
	if (t_info.inHtmTransactionalState()) {
	DPRINTF(HtmCpu, "Deferring pending interrupt - %s -"
	"due to transactional state\n",
	interrupt->name());
	return;
	}

	t_info.fetchOffset = 0;
	interrupts[curThread]->updateIntrInfo();
	interrupt->invoke(tc);
	thread->decoder.reset();
	}
	}
	}


	void
	BaseSimpleCPU::setupFetchRequest(const RequestPtr &req)
	{
	SimpleExecContext &t_info = *threadInfo[curThread];
	SimpleThread* thread = t_info.thread;

	Addr instAddr = thread->instAddr();
	Addr fetchPC = (instAddr & PCMask) + t_info.fetchOffset;

	// set up memory request for instruction fetch
	DPRINTF(Fetch, "Fetch: Inst PC:%08p, Fetch PC:%08p\n", instAddr, fetchPC);

	req->setVirt(fetchPC, sizeof(TheISA::MachInst), Request::INST_FETCH,
	instRequestorId(), instAddr);
	}


	void
	BaseSimpleCPU::preExecute()
	{
	SimpleExecContext &t_info = *threadInfo[curThread];
	SimpleThread* thread = t_info.thread;

	// maintain $r0 semantics
	thread->setIntReg(TheISA::ZeroReg, 0);

	// resets predicates
	t_info.setPredicate(true);
	t_info.setMemAccPredicate(true);

	// check for instruction-count-based events
	thread->comInstEventQueue.serviceEvents(t_info.numInst);

	// decode the instruction
	TheISA::PCState pcState = thread->pcState();

	if (isRomMicroPC(pcState.microPC())) {
	t_info.stayAtPC = false;
	curStaticInst = thread->decoder.fetchRomMicroop(
	pcState.microPC(), curMacroStaticInst);
	} else if (!curMacroStaticInst) {
	//We're not in the middle of a macro instruction
	StaticInstPtr instPtr = NULL;

	TheISA::Decoder *decoder = &(thread->decoder);

	//Predecode, ie bundle up an ExtMachInst
	//If more fetch data is needed, pass it in.
	Addr fetchPC = (pcState.instAddr() & PCMask) + t_info.fetchOffset;
	//if (decoder->needMoreBytes())
	decoder->moreBytes(pcState, fetchPC, inst);
	//else
	// decoder->process();

	//Decode an instruction if one is ready. Otherwise, we'll have to
	//fetch beyond the MachInst at the current pc.
	instPtr = decoder->decode(pcState);
	if (instPtr) {
	t_info.stayAtPC = false;
	thread->pcState(pcState);
	} else {
	t_info.stayAtPC = true;
	t_info.fetchOffset += sizeof(TheISA::MachInst);
	}

	//If we decoded an instruction and it's microcoded, start pulling
	//out micro ops
	if (instPtr && instPtr->isMacroop()) {
	curMacroStaticInst = instPtr;
	curStaticInst =
	curMacroStaticInst->fetchMicroop(pcState.microPC());
	} else {
	curStaticInst = instPtr;
	}
	} else {
	//Read the next micro op from the macro op
	curStaticInst = curMacroStaticInst->fetchMicroop(pcState.microPC());
	}

	//If we decoded an instruction this "tick", record information about it.
	if (curStaticInst) {
	#if TRACING_ON
	traceData = tracer->getInstRecord(curTick(), thread->getTC(),
	curStaticInst, thread->pcState(), curMacroStaticInst);
	#endif // TRACING_ON
	}

	if (branchPred && curStaticInst &&
	curStaticInst->isControl()) {
	// Use a fake sequence number since we only have one
	// instruction in flight at the same time.
	const InstSeqNum cur_sn(0);
	t_info.predPC = thread->pcState();
	const bool predict_taken(
	branchPred->predict(curStaticInst, cur_sn, t_info.predPC,
	curThread));

	if (predict_taken)
	++t_info.execContextStats.numPredictedBranches;
	}
	}

	void
	BaseSimpleCPU::postExecute()
	{
	SimpleExecContext &t_info = *threadInfo[curThread];

	assert(curStaticInst);

	TheISA::PCState pc = threadContexts[curThread]->pcState();
	Addr instAddr = pc.instAddr();

	if (curStaticInst->isMemRef()) {
	t_info.execContextStats.numMemRefs++;
	}

	if (curStaticInst->isLoad()) {
	++t_info.numLoad;
	}

	if (curStaticInst->isControl()) {
	++t_info.execContextStats.numBranches;
	}

	/* Power model statistics */
	//integer alu accesses
	if (curStaticInst->isInteger()){
	t_info.execContextStats.numIntAluAccesses++;
	t_info.execContextStats.numIntInsts++;
	}

	//float alu accesses
	if (curStaticInst->isFloating()){
	t_info.execContextStats.numFpAluAccesses++;
	t_info.execContextStats.numFpInsts++;
	}

	//vector alu accesses
	if (curStaticInst->isVector()){
	t_info.execContextStats.numVecAluAccesses++;
	t_info.execContextStats.numVecInsts++;
	}

	//number of function calls/returns to get window accesses
	if (curStaticInst->isCall() \|\| curStaticInst->isReturn()){
	t_info.execContextStats.numCallsReturns++;
	}

	//the number of branch predictions that will be made
	if (curStaticInst->isCondCtrl()){
	t_info.execContextStats.numCondCtrlInsts++;
	}

	//result bus acceses
	if (curStaticInst->isLoad()){
	t_info.execContextStats.numLoadInsts++;
	}

	if (curStaticInst->isStore() \|\| curStaticInst->isAtomic()){
	t_info.execContextStats.numStoreInsts++;
	}
	/* End power model statistics */

	t_info.execContextStats.statExecutedInstType[curStaticInst->opClass()]++;

	if (FullSystem)
	traceFunctions(instAddr);

	if (traceData) {
	traceData->dump();
	delete traceData;
	traceData = NULL;
	}

	// Call CPU instruction commit probes
	probeInstCommit(curStaticInst, instAddr);
	}

	void
	BaseSimpleCPU::advancePC(const Fault &fault)
	{
	SimpleExecContext &t_info = *threadInfo[curThread];
	SimpleThread* thread = t_info.thread;

	const bool branching(thread->pcState().branching());

	//Since we're moving to a new pc, zero out the offset
	t_info.fetchOffset = 0;
	if (fault != NoFault) {
	curMacroStaticInst = StaticInst::nullStaticInstPtr;
	fault->invoke(threadContexts[curThread], curStaticInst);
	thread->decoder.reset();
	} else {
	if (curStaticInst) {
	if (curStaticInst->isLastMicroop())
	curMacroStaticInst = StaticInst::nullStaticInstPtr;
	TheISA::PCState pcState = thread->pcState();
	TheISA::advancePC(pcState, curStaticInst);
	thread->pcState(pcState);
	}
	}

	if (branchPred && curStaticInst && curStaticInst->isControl()) {
	// Use a fake sequence number since we only have one
	// instruction in flight at the same time.
	const InstSeqNum cur_sn(0);

	if (t_info.predPC == thread->pcState()) {
	// Correctly predicted branch
	branchPred->update(cur_sn, curThread);
	} else {
	// Mis-predicted branch
	branchPred->squash(cur_sn, thread->pcState(), branching, curThread);
	++t_info.execContextStats.numBranchMispred;
	}
	}
	}