src/cpu/minor/scoreboard.cc - public/gem5 - Git at Google

 /*
  * Copyright (c) 2013-2014, 2016-2017 ARM Limited
  * 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.
  *
  * 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.
  *
  * Authors: Andrew Bardsley
  */

 #include "cpu/minor/scoreboard.hh"

 #include "arch/registers.hh"
 #include "cpu/reg_class.hh"
 #include "debug/MinorScoreboard.hh"
 #include "debug/MinorTiming.hh"

 namespace Minor
 {

 bool
 Scoreboard::findIndex(const RegId& reg, Index &scoreboard_index)
 {
     bool ret = false;

     if (reg.isZeroReg()) {
         /* Don't bother with the zero register */
         ret = false;
     } else {
         switch (reg.classValue())
         {
           case IntRegClass:
             scoreboard_index = reg.index();
             ret = true;
             break;
           case FloatRegClass:
             scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
                 reg.index();
             ret = true;
             break;
           case VecRegClass:
             scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
                 TheISA::NumFloatRegs + reg.index();
             ret = true;
             break;
           case VecElemClass:
             scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
                 TheISA::NumFloatRegs + reg.flatIndex();
             ret = true;
             break;
           case VecPredRegClass:
             scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
                 TheISA::NumFloatRegs + TheISA::NumVecRegs + reg.index();
             ret = true;
             break;
           case CCRegClass:
             scoreboard_index = TheISA::NumIntRegs + reg.index();
             ret = true;
             break;
           case MiscRegClass:
               /* Don't bother with Misc registers */
             ret = false;
             break;
           default:
             panic("Unknown register class: %d",
                     static_cast<int>(reg.classValue()));
         }
     }

     return ret;
 }

 /** Flatten a RegId, irrespective of what reg type it's pointing to */
 static RegId
 flattenRegIndex(const RegId& reg, ThreadContext *thread_context)
 {
     return thread_context->flattenRegId(reg);
 }

 void
 Scoreboard::markupInstDests(MinorDynInstPtr inst, Cycles retire_time,
     ThreadContext *thread_context, bool mark_unpredictable)
 {
     if (inst->isFault())
         return;

     StaticInstPtr staticInst = inst->staticInst;
     unsigned int num_dests = staticInst->numDestRegs();

     /** Mark each destination register */
     for (unsigned int dest_index = 0; dest_index < num_dests;
         dest_index++)
     {
         RegId reg = flattenRegIndex(
                 staticInst->destRegIdx(dest_index), thread_context);
         Index index;

         if (findIndex(reg, index)) {
             if (mark_unpredictable)
                 numUnpredictableResults[index]++;

             inst->flatDestRegIdx[dest_index] = reg;

             numResults[index]++;
             returnCycle[index] = retire_time;
             /* We should be able to rely on only being given accending
              *  execSeqNums, but sanity check */
             if (inst->id.execSeqNum > writingInst[index]) {
                 writingInst[index] = inst->id.execSeqNum;
                 fuIndices[index] = inst->fuIndex;
             }

             DPRINTF(MinorScoreboard, "Marking up inst: %s"
                 " regIndex: %d final numResults: %d returnCycle: %d\n",
                 *inst, index, numResults[index], returnCycle[index]);
         } else {
             /* Use ZeroReg to mark invalid/untracked dests */
             inst->flatDestRegIdx[dest_index] = RegId(IntRegClass,
                                                      TheISA::ZeroReg);
         }
     }
 }

 InstSeqNum
 Scoreboard::execSeqNumToWaitFor(MinorDynInstPtr inst,
     ThreadContext *thread_context)
 {
     InstSeqNum ret = 0;

     if (inst->isFault())
         return ret;

     StaticInstPtr staticInst = inst->staticInst;
     unsigned int num_srcs = staticInst->numSrcRegs();

     for (unsigned int src_index = 0; src_index < num_srcs; src_index++) {
         RegId reg = flattenRegIndex(staticInst->srcRegIdx(src_index),
             thread_context);
         unsigned short int index;

         if (findIndex(reg, index)) {
             if (writingInst[index] > ret)
                 ret = writingInst[index];
         }
     }

     DPRINTF(MinorScoreboard, "Inst: %s depends on execSeqNum: %d\n",
         *inst, ret);

     return ret;
 }

 void
 Scoreboard::clearInstDests(MinorDynInstPtr inst, bool clear_unpredictable)
 {
     if (inst->isFault())
         return;

     StaticInstPtr staticInst = inst->staticInst;
     unsigned int num_dests = staticInst->numDestRegs();

     /** Mark each destination register */
     for (unsigned int dest_index = 0; dest_index < num_dests;
         dest_index++)
     {
         const RegId& reg = inst->flatDestRegIdx[dest_index];
         Index index;

         if (findIndex(reg, index)) {
             if (clear_unpredictable && numUnpredictableResults[index] != 0)
                 numUnpredictableResults[index] --;

             numResults[index] --;

             if (numResults[index] == 0) {
                 returnCycle[index] = Cycles(0);
                 writingInst[index] = 0;
                 fuIndices[index] = -1;
             }

             DPRINTF(MinorScoreboard, "Clearing inst: %s"
                 " regIndex: %d final numResults: %d\n",
                 *inst, index, numResults[index]);
         }
     }
 }

 bool
 Scoreboard::canInstIssue(MinorDynInstPtr inst,
     const std::vector<Cycles> *src_reg_relative_latencies,
     const std::vector<bool> *cant_forward_from_fu_indices,
     Cycles now, ThreadContext *thread_context)
 {
     /* Always allow fault to be issued */
     if (inst->isFault())
         return true;

     StaticInstPtr staticInst = inst->staticInst;
     unsigned int num_srcs = staticInst->numSrcRegs();

     /* Default to saying you can issue */
     bool ret = true;

     unsigned int num_relative_latencies = 0;
     Cycles default_relative_latency = Cycles(0);

     /* Where relative latencies are given, the default is the last
      *  one as that allows the rel. lat. list to be shorted than the
      *  number of src. regs */
     if (src_reg_relative_latencies &&
         src_reg_relative_latencies->size() != 0)
     {
         num_relative_latencies = src_reg_relative_latencies->size();
         default_relative_latency = (*src_reg_relative_latencies)
             [num_relative_latencies-1];
     }

     /* For each source register, find the latest result */
     unsigned int src_index = 0;
     while (src_index < num_srcs && /* More registers */
         ret /* Still possible */)
     {
         RegId reg = flattenRegIndex(staticInst->srcRegIdx(src_index),
             thread_context);
         unsigned short int index;

         if (findIndex(reg, index)) {
             bool cant_forward = fuIndices[index] != 1 &&
                 cant_forward_from_fu_indices &&
                 index < cant_forward_from_fu_indices->size() &&
                 (*cant_forward_from_fu_indices)[index];

             Cycles relative_latency = (cant_forward ? Cycles(0) :
                 (src_index >= num_relative_latencies ?
                     default_relative_latency :
                     (*src_reg_relative_latencies)[src_index]));

             if (returnCycle[index] > (now + relative_latency) ||
                 numUnpredictableResults[index] != 0)
             {
                 ret = false;
             }
         }
         src_index++;
     }

     if (DTRACE(MinorTiming)) {
         if (ret && num_srcs > num_relative_latencies &&
             num_relative_latencies != 0)
         {
             DPRINTF(MinorTiming, "Warning, inst: %s timing extra decode has"
                 " more src. regs: %d than relative latencies: %d\n",
                 staticInst->disassemble(0), num_srcs, num_relative_latencies);
         }
     }

     return ret;
 }

 void
 Scoreboard::minorTrace() const
 {
     std::ostringstream result_stream;

     bool printed_element = false;

     unsigned int i = 0;
     while (i < numRegs) {
         unsigned short int num_results = numResults[i];
         unsigned short int num_unpredictable_results =
             numUnpredictableResults[i];

         if (!(num_results == 0 && num_unpredictable_results == Cycles(0))) {
             if (printed_element)
                 result_stream << ',';

             result_stream << '(' << i << ','
                  << num_results << '/'
                  << num_unpredictable_results << '/'
                  << returnCycle[i] << '/'
                  << writingInst[i] << ')';

             printed_element = true;
         }

         i++;
     }

     MINORTRACE("busy=%s\n", result_stream.str());
 }

 }
	/*
	* Copyright (c) 2013-2014, 2016-2017 ARM Limited
	* 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.
	*
	* 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.
	*
	* Authors: Andrew Bardsley
	*/

	#include "cpu/minor/scoreboard.hh"

	#include "arch/registers.hh"
	#include "cpu/reg_class.hh"
	#include "debug/MinorScoreboard.hh"
	#include "debug/MinorTiming.hh"

	namespace Minor
	{

	bool
	Scoreboard::findIndex(const RegId& reg, Index &scoreboard_index)
	{
	bool ret = false;

	if (reg.isZeroReg()) {
	/* Don't bother with the zero register */
	ret = false;
	} else {
	switch (reg.classValue())
	{
	case IntRegClass:
	scoreboard_index = reg.index();
	ret = true;
	break;
	case FloatRegClass:
	scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
	reg.index();
	ret = true;
	break;
	case VecRegClass:
	scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
	TheISA::NumFloatRegs + reg.index();
	ret = true;
	break;
	case VecElemClass:
	scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
	TheISA::NumFloatRegs + reg.flatIndex();
	ret = true;
	break;
	case VecPredRegClass:
	scoreboard_index = TheISA::NumIntRegs + TheISA::NumCCRegs +
	TheISA::NumFloatRegs + TheISA::NumVecRegs + reg.index();
	ret = true;
	break;
	case CCRegClass:
	scoreboard_index = TheISA::NumIntRegs + reg.index();
	ret = true;
	break;
	case MiscRegClass:
	/* Don't bother with Misc registers */
	ret = false;
	break;
	default:
	panic("Unknown register class: %d",
	static_cast<int>(reg.classValue()));
	}
	}

	return ret;
	}

	/** Flatten a RegId, irrespective of what reg type it's pointing to */
	static RegId
	flattenRegIndex(const RegId& reg, ThreadContext *thread_context)
	{
	return thread_context->flattenRegId(reg);
	}

	void
	Scoreboard::markupInstDests(MinorDynInstPtr inst, Cycles retire_time,
	ThreadContext *thread_context, bool mark_unpredictable)
	{
	if (inst->isFault())
	return;

	StaticInstPtr staticInst = inst->staticInst;
	unsigned int num_dests = staticInst->numDestRegs();

	/** Mark each destination register */
	for (unsigned int dest_index = 0; dest_index < num_dests;
	dest_index++)
	{
	RegId reg = flattenRegIndex(
	staticInst->destRegIdx(dest_index), thread_context);
	Index index;

	if (findIndex(reg, index)) {
	if (mark_unpredictable)
	numUnpredictableResults[index]++;

	inst->flatDestRegIdx[dest_index] = reg;

	numResults[index]++;
	returnCycle[index] = retire_time;
	/* We should be able to rely on only being given accending
	* execSeqNums, but sanity check */
	if (inst->id.execSeqNum > writingInst[index]) {
	writingInst[index] = inst->id.execSeqNum;
	fuIndices[index] = inst->fuIndex;
	}

	DPRINTF(MinorScoreboard, "Marking up inst: %s"
	" regIndex: %d final numResults: %d returnCycle: %d\n",
	*inst, index, numResults[index], returnCycle[index]);
	} else {
	/* Use ZeroReg to mark invalid/untracked dests */
	inst->flatDestRegIdx[dest_index] = RegId(IntRegClass,
	TheISA::ZeroReg);
	}
	}
	}

	InstSeqNum
	Scoreboard::execSeqNumToWaitFor(MinorDynInstPtr inst,
	ThreadContext *thread_context)
	{
	InstSeqNum ret = 0;

	if (inst->isFault())
	return ret;

	StaticInstPtr staticInst = inst->staticInst;
	unsigned int num_srcs = staticInst->numSrcRegs();

	for (unsigned int src_index = 0; src_index < num_srcs; src_index++) {
	RegId reg = flattenRegIndex(staticInst->srcRegIdx(src_index),
	thread_context);
	unsigned short int index;

	if (findIndex(reg, index)) {
	if (writingInst[index] > ret)
	ret = writingInst[index];
	}
	}

	DPRINTF(MinorScoreboard, "Inst: %s depends on execSeqNum: %d\n",
	*inst, ret);

	return ret;
	}

	void
	Scoreboard::clearInstDests(MinorDynInstPtr inst, bool clear_unpredictable)
	{
	if (inst->isFault())
	return;

	StaticInstPtr staticInst = inst->staticInst;
	unsigned int num_dests = staticInst->numDestRegs();

	/** Mark each destination register */
	for (unsigned int dest_index = 0; dest_index < num_dests;
	dest_index++)
	{
	const RegId& reg = inst->flatDestRegIdx[dest_index];
	Index index;

	if (findIndex(reg, index)) {
	if (clear_unpredictable && numUnpredictableResults[index] != 0)
	numUnpredictableResults[index] --;

	numResults[index] --;

	if (numResults[index] == 0) {
	returnCycle[index] = Cycles(0);
	writingInst[index] = 0;
	fuIndices[index] = -1;
	}

	DPRINTF(MinorScoreboard, "Clearing inst: %s"
	" regIndex: %d final numResults: %d\n",
	*inst, index, numResults[index]);
	}
	}
	}

	bool
	Scoreboard::canInstIssue(MinorDynInstPtr inst,
	const std::vector<Cycles> *src_reg_relative_latencies,
	const std::vector<bool> *cant_forward_from_fu_indices,
	Cycles now, ThreadContext *thread_context)
	{
	/* Always allow fault to be issued */
	if (inst->isFault())
	return true;

	StaticInstPtr staticInst = inst->staticInst;
	unsigned int num_srcs = staticInst->numSrcRegs();

	/* Default to saying you can issue */
	bool ret = true;

	unsigned int num_relative_latencies = 0;
	Cycles default_relative_latency = Cycles(0);

	/* Where relative latencies are given, the default is the last
	* one as that allows the rel. lat. list to be shorted than the
	* number of src. regs */
	if (src_reg_relative_latencies &&
	src_reg_relative_latencies->size() != 0)
	{
	num_relative_latencies = src_reg_relative_latencies->size();
	default_relative_latency = (*src_reg_relative_latencies)
	[num_relative_latencies-1];
	}

	/* For each source register, find the latest result */
	unsigned int src_index = 0;
	while (src_index < num_srcs && /* More registers */
	ret /* Still possible */)
	{
	RegId reg = flattenRegIndex(staticInst->srcRegIdx(src_index),
	thread_context);
	unsigned short int index;

	if (findIndex(reg, index)) {
	bool cant_forward = fuIndices[index] != 1 &&
	cant_forward_from_fu_indices &&
	index < cant_forward_from_fu_indices->size() &&
	(*cant_forward_from_fu_indices)[index];

	Cycles relative_latency = (cant_forward ? Cycles(0) :
	(src_index >= num_relative_latencies ?
	default_relative_latency :
	(*src_reg_relative_latencies)[src_index]));

	if (returnCycle[index] > (now + relative_latency) \|\|
	numUnpredictableResults[index] != 0)
	{
	ret = false;
	}
	}
	src_index++;
	}

	if (DTRACE(MinorTiming)) {
	if (ret && num_srcs > num_relative_latencies &&
	num_relative_latencies != 0)
	{
	DPRINTF(MinorTiming, "Warning, inst: %s timing extra decode has"
	" more src. regs: %d than relative latencies: %d\n",
	staticInst->disassemble(0), num_srcs, num_relative_latencies);
	}
	}

	return ret;
	}

	void
	Scoreboard::minorTrace() const
	{
	std::ostringstream result_stream;

	bool printed_element = false;

	unsigned int i = 0;
	while (i < numRegs) {
	unsigned short int num_results = numResults[i];
	unsigned short int num_unpredictable_results =
	numUnpredictableResults[i];

	if (!(num_results == 0 && num_unpredictable_results == Cycles(0))) {
	if (printed_element)
	result_stream << ',';

	result_stream << '(' << i << ','
	<< num_results << '/'
	<< num_unpredictable_results << '/'
	<< returnCycle[i] << '/'
	<< writingInst[i] << ')';

	printed_element = true;
	}

	i++;
	}

	MINORTRACE("busy=%s\n", result_stream.str());
	}

	}