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/*
* Copyright (c) 2004-2005 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.
*
* Authors: Kevin Lim
*/
#ifndef __CPU_O3_FREE_LIST_HH__
#define __CPU_O3_FREE_LIST_HH__
#include <iostream>
#include <queue>
#include "arch/isa_traits.hh"
#include "base/misc.hh"
#include "base/trace.hh"
#include "base/traceflags.hh"
#include "cpu/o3/comm.hh"
/**
* FreeList class that simply holds the list of free integer and floating
* point registers. Can request for a free register of either type, and
* also send back free registers of either type. This is a very simple
* class, but it should be sufficient for most implementations. Like all
* other classes, it assumes that the indices for the floating point
* registers starts after the integer registers end. Hence the variable
* numPhysicalIntRegs is logically equivalent to the baseFP dependency.
* Note that while this most likely should be called FreeList, the name
* "FreeList" is used in a typedef within the CPU Policy, and therefore no
* class can be named simply "FreeList".
* @todo: Give a better name to the base FP dependency.
*/
class SimpleFreeList
{
private:
/** The list of free integer registers. */
std::queue<PhysRegIndex> freeIntRegs;
/** The list of free floating point registers. */
std::queue<PhysRegIndex> freeFloatRegs;
/** Number of logical integer registers. */
int numLogicalIntRegs;
/** Number of physical integer registers. */
int numPhysicalIntRegs;
/** Number of logical floating point registers. */
int numLogicalFloatRegs;
/** Number of physical floating point registers. */
int numPhysicalFloatRegs;
/** Total number of physical registers. */
int numPhysicalRegs;
public:
/** Constructs a free list.
* @param activeThreads Number of active threads.
* @param _numLogicalIntRegs Number of logical integer registers.
* @param _numPhysicalIntRegs Number of physical integer registers.
* @param _numLogicalFloatRegs Number of logical fp registers.
* @param _numPhysicalFloatRegs Number of physical fp registers.
*/
SimpleFreeList(unsigned activeThreads,
unsigned _numLogicalIntRegs,
unsigned _numPhysicalIntRegs,
unsigned _numLogicalFloatRegs,
unsigned _numPhysicalFloatRegs);
/** Gives the name of the freelist. */
std::string name() const;
/** Gets a free integer register. */
inline PhysRegIndex getIntReg();
/** Gets a free fp register. */
inline PhysRegIndex getFloatReg();
/** Adds a register back to the free list. */
inline void addReg(PhysRegIndex freed_reg);
/** Adds an integer register back to the free list. */
inline void addIntReg(PhysRegIndex freed_reg);
/** Adds a fp register back to the free list. */
inline void addFloatReg(PhysRegIndex freed_reg);
/** Checks if there are any free integer registers. */
bool hasFreeIntRegs()
{ return !freeIntRegs.empty(); }
/** Checks if there are any free fp registers. */
bool hasFreeFloatRegs()
{ return !freeFloatRegs.empty(); }
/** Returns the number of free integer registers. */
int numFreeIntRegs()
{ return freeIntRegs.size(); }
/** Returns the number of free fp registers. */
int numFreeFloatRegs()
{ return freeFloatRegs.size(); }
};
inline PhysRegIndex
SimpleFreeList::getIntReg()
{
DPRINTF(FreeList, "Trying to get free integer register.\n");
if (freeIntRegs.empty()) {
panic("No free integer registers!");
}
PhysRegIndex free_reg = freeIntRegs.front();
freeIntRegs.pop();
return(free_reg);
}
inline PhysRegIndex
SimpleFreeList::getFloatReg()
{
DPRINTF(FreeList, "Trying to get free float register.\n");
if (freeFloatRegs.empty()) {
panic("No free integer registers!");
}
PhysRegIndex free_reg = freeFloatRegs.front();
freeFloatRegs.pop();
return(free_reg);
}
inline void
SimpleFreeList::addReg(PhysRegIndex freed_reg)
{
DPRINTF(FreeList,"Freeing register %i.\n", freed_reg);
//Might want to add in a check for whether or not this register is
//already in there. A bit vector or something similar would be useful.
if (freed_reg < numPhysicalIntRegs) {
if (freed_reg != TheISA::ZeroReg)
freeIntRegs.push(freed_reg);
} else if (freed_reg < numPhysicalRegs) {
#if THE_ISA == ALPHA_ISA
if (freed_reg != (TheISA::ZeroReg + numPhysicalIntRegs))
#endif
freeFloatRegs.push(freed_reg);
}
// These assert conditions ensure that the number of free
// registers are not more than the # of total Physical Registers.
// If this were false, it would mean that registers
// have been freed twice, overflowing the free register
// pool and potentially crashing SMT workloads.
// ----
// Comment out for now so as to not potentially break
// CMP and single-threaded workloads
// ----
// assert(freeIntRegs.size() <= numPhysicalIntRegs);
// assert(freeFloatRegs.size() <= numPhysicalFloatRegs);
}
inline void
SimpleFreeList::addIntReg(PhysRegIndex freed_reg)
{
DPRINTF(FreeList,"Freeing int register %i.\n", freed_reg);
freeIntRegs.push(freed_reg);
}
inline void
SimpleFreeList::addFloatReg(PhysRegIndex freed_reg)
{
DPRINTF(FreeList,"Freeing float register %i.\n", freed_reg);
freeFloatRegs.push(freed_reg);
}
#endif // __CPU_O3_FREE_LIST_HH__
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