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/*
* Copyright (c) 2012-2013 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.
*
* 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.
*
* 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: Kevin Lim
*/
#ifndef __CPU_O3_FU_POOL_HH__
#define __CPU_O3_FU_POOL_HH__
#include <array>
#include <bitset>
#include <list>
#include <string>
#include <vector>
#include "cpu/op_class.hh"
#include "params/FUPool.hh"
#include "sim/sim_object.hh"
class FUDesc;
class FuncUnit;
/**
* Pool of FU's, specific to the new CPU model. The old FU pool had lists of
* free units and busy units, and whenever a FU was needed it would iterate
* through the free units to find a FU that provided the capability. This pool
* has lists of units specific to each of the capabilities, and whenever a FU
* is needed, it iterates through that list to find a free unit. The previous
* FU pool would have to be ticked each cycle to update which units became
* free. This FU pool lets the IEW stage handle freeing units, which frees
* them as their scheduled execution events complete. This limits units in this
* model to either have identical issue and op latencies, or 1 cycle issue
* latencies.
*/
class FUPool : public SimObject
{
private:
/** Maximum op execution latencies, per op class. */
std::array<Cycles, Num_OpClasses> maxOpLatencies;
/** Whether op is pipelined or not. */
std::array<bool, Num_OpClasses> pipelined;
/** Bitvector listing capabilities of this FU pool. */
std::bitset<Num_OpClasses> capabilityList;
/** Bitvector listing which FUs are busy. */
std::vector<bool> unitBusy;
/** List of units to be freed at the end of this cycle. */
std::vector<int> unitsToBeFreed;
/**
* Class that implements a circular queue to hold FU indices. The hope is
* that FUs that have been just used will be moved to the end of the queue
* by iterating through it, thus leaving free units at the head of the
* queue.
*/
class FUIdxQueue {
public:
/** Constructs a circular queue of FU indices. */
FUIdxQueue()
: idx(0), size(0)
{ }
/** Adds a FU to the queue. */
inline void addFU(int fu_idx);
/** Returns the index of the FU at the head of the queue, and changes
* the index to the next element.
*/
inline int getFU();
private:
/** Circular queue index. */
int idx;
/** Size of the queue. */
int size;
/** Queue of FU indices. */
std::vector<int> funcUnitsIdx;
};
/** Per op class queues of FUs that provide that capability. */
FUIdxQueue fuPerCapList[Num_OpClasses];
/** Number of FUs. */
int numFU;
/** Functional units. */
std::vector<FuncUnit *> funcUnits;
typedef std::vector<FuncUnit *>::iterator fuListIterator;
public:
typedef FUPoolParams Params;
/** Constructs a FU pool. */
FUPool(const Params *p);
~FUPool();
static constexpr auto NoCapableFU = -2;
static constexpr auto NoFreeFU = -1;
/**
* Gets a FU providing the requested capability. Will mark the
* unit as busy, but leaves the freeing of the unit up to the IEW
* stage.
*
* @param capability The capability requested.
* @return Returns NoCapableFU if the FU pool does not have the
* capability, NoFreeFU if there is no free FU, and the FU's index
* otherwise.
*/
int getUnit(OpClass capability);
/** Frees a FU at the end of this cycle. */
void freeUnitNextCycle(int fu_idx);
/** Frees all FUs on the list. */
void processFreeUnits();
/** Returns the total number of FUs. */
int size() { return numFU; }
/** Debugging function used to dump FU information. */
void dump();
/** Returns the operation execution latency of the given capability. */
Cycles getOpLatency(OpClass capability) {
return maxOpLatencies[capability];
}
/** Returns the issue latency of the given capability. */
bool isPipelined(OpClass capability) {
return pipelined[capability];
}
/** Have all the FUs drained? */
bool isDrained() const;
/** Takes over from another CPU's thread. */
void takeOverFrom() {};
};
#endif // __CPU_O3_FU_POOL_HH__
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