+++ /dev/null
-/*
- * Copyright (c) 2004-2006 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
- */
-
-#include "base/intmath.hh"
-#include "base/misc.hh"
-#include "base/trace.hh"
-#include "cpu/o3/2bit_local_pred.hh"
-
-LocalBP::LocalBP(unsigned _localPredictorSize,
- unsigned _localCtrBits,
- unsigned _instShiftAmt)
- : localPredictorSize(_localPredictorSize),
- localCtrBits(_localCtrBits),
- instShiftAmt(_instShiftAmt)
-{
- if (!isPowerOf2(localPredictorSize)) {
- fatal("Invalid local predictor size!\n");
- }
-
- localPredictorSets = localPredictorSize / localCtrBits;
-
- if (!isPowerOf2(localPredictorSets)) {
- fatal("Invalid number of local predictor sets! Check localCtrBits.\n");
- }
-
- // Setup the index mask.
- indexMask = localPredictorSets - 1;
-
- DPRINTF(Fetch, "Branch predictor: index mask: %#x\n", indexMask);
-
- // Setup the array of counters for the local predictor.
- localCtrs.resize(localPredictorSets);
-
- for (int i = 0; i < localPredictorSets; ++i)
- localCtrs[i].setBits(_localCtrBits);
-
- DPRINTF(Fetch, "Branch predictor: local predictor size: %i\n",
- localPredictorSize);
-
- DPRINTF(Fetch, "Branch predictor: local counter bits: %i\n", localCtrBits);
-
- DPRINTF(Fetch, "Branch predictor: instruction shift amount: %i\n",
- instShiftAmt);
-}
-
-void
-LocalBP::reset()
-{
- for (int i = 0; i < localPredictorSets; ++i) {
- localCtrs[i].reset();
- }
-}
-
-bool
-LocalBP::lookup(Addr &branch_addr, void * &bp_history)
-{
- bool taken;
- uint8_t counter_val;
- unsigned local_predictor_idx = getLocalIndex(branch_addr);
-
- DPRINTF(Fetch, "Branch predictor: Looking up index %#x\n",
- local_predictor_idx);
-
- counter_val = localCtrs[local_predictor_idx].read();
-
- DPRINTF(Fetch, "Branch predictor: prediction is %i.\n",
- (int)counter_val);
-
- taken = getPrediction(counter_val);
-
-#if 0
- // Speculative update.
- if (taken) {
- DPRINTF(Fetch, "Branch predictor: Branch updated as taken.\n");
- localCtrs[local_predictor_idx].increment();
- } else {
- DPRINTF(Fetch, "Branch predictor: Branch updated as not taken.\n");
- localCtrs[local_predictor_idx].decrement();
- }
-#endif
-
- return taken;
-}
-
-void
-LocalBP::update(Addr &branch_addr, bool taken, void *bp_history)
-{
- assert(bp_history == NULL);
- unsigned local_predictor_idx;
-
- // Update the local predictor.
- local_predictor_idx = getLocalIndex(branch_addr);
-
- DPRINTF(Fetch, "Branch predictor: Looking up index %#x\n",
- local_predictor_idx);
-
- if (taken) {
- DPRINTF(Fetch, "Branch predictor: Branch updated as taken.\n");
- localCtrs[local_predictor_idx].increment();
- } else {
- DPRINTF(Fetch, "Branch predictor: Branch updated as not taken.\n");
- localCtrs[local_predictor_idx].decrement();
- }
-}
-
-inline
-bool
-LocalBP::getPrediction(uint8_t &count)
-{
- // Get the MSB of the count
- return (count >> (localCtrBits - 1));
-}
-
-inline
-unsigned
-LocalBP::getLocalIndex(Addr &branch_addr)
-{
- return (branch_addr >> instShiftAmt) & indexMask;
-}
Source('thread_context.cc')
Source('thread_state.cc')
-if 'InOrderCPU' in env['CPU_MODELS'] or 'O3CPU' in env['CPU_MODELS']:
- Source('btb.cc')
- Source('tournament_pred.cc')
- Source('2bit_local_pred.cc')
- Source('ras.cc')
- TraceFlag('FreeList')
-
if env['FULL_SYSTEM']:
SimObject('IntrControl.py')
+++ /dev/null
-/*
- * 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
- */
-
-#include "base/intmath.hh"
-#include "base/trace.hh"
-#include "cpu/o3/btb.hh"
-
-DefaultBTB::DefaultBTB(unsigned _numEntries,
- unsigned _tagBits,
- unsigned _instShiftAmt)
- : numEntries(_numEntries),
- tagBits(_tagBits),
- instShiftAmt(_instShiftAmt)
-{
- DPRINTF(Fetch, "BTB: Creating BTB object.\n");
-
- if (!isPowerOf2(numEntries)) {
- fatal("BTB entries is not a power of 2!");
- }
-
- btb.resize(numEntries);
-
- for (int i = 0; i < numEntries; ++i) {
- btb[i].valid = false;
- }
-
- idxMask = numEntries - 1;
-
- tagMask = (1 << tagBits) - 1;
-
- tagShiftAmt = instShiftAmt + floorLog2(numEntries);
-}
-
-void
-DefaultBTB::reset()
-{
- for (int i = 0; i < numEntries; ++i) {
- btb[i].valid = false;
- }
-}
-
-inline
-unsigned
-DefaultBTB::getIndex(const Addr &inst_PC)
-{
- // Need to shift PC over by the word offset.
- return (inst_PC >> instShiftAmt) & idxMask;
-}
-
-inline
-Addr
-DefaultBTB::getTag(const Addr &inst_PC)
-{
- return (inst_PC >> tagShiftAmt) & tagMask;
-}
-
-bool
-DefaultBTB::valid(const Addr &inst_PC, ThreadID tid)
-{
- unsigned btb_idx = getIndex(inst_PC);
-
- Addr inst_tag = getTag(inst_PC);
-
- assert(btb_idx < numEntries);
-
- if (btb[btb_idx].valid
- && inst_tag == btb[btb_idx].tag
- && btb[btb_idx].tid == tid) {
- return true;
- } else {
- return false;
- }
-}
-
-// @todo Create some sort of return struct that has both whether or not the
-// address is valid, and also the address. For now will just use addr = 0 to
-// represent invalid entry.
-Addr
-DefaultBTB::lookup(const Addr &inst_PC, ThreadID tid)
-{
- unsigned btb_idx = getIndex(inst_PC);
-
- Addr inst_tag = getTag(inst_PC);
-
- assert(btb_idx < numEntries);
-
- if (btb[btb_idx].valid
- && inst_tag == btb[btb_idx].tag
- && btb[btb_idx].tid == tid) {
- return btb[btb_idx].target;
- } else {
- return 0;
- }
-}
-
-void
-DefaultBTB::update(const Addr &inst_PC, const Addr &target, ThreadID tid)
-{
- unsigned btb_idx = getIndex(inst_PC);
-
- assert(btb_idx < numEntries);
-
- btb[btb_idx].tid = tid;
- btb[btb_idx].valid = true;
- btb[btb_idx].target = target;
- btb[btb_idx].tag = getTag(inst_PC);
-}
#ifndef __CPU_INORDER_BPRED_UNIT_HH__
#define __CPU_INORDER_BPRED_UNIT_HH__
-// For Addr type.
+#include <list>
+
#include "arch/isa_traits.hh"
#include "base/statistics.hh"
#include "cpu/inst_seq.hh"
-
-//#include "cpu/inorder/params.hh"
-#include "cpu/o3/2bit_local_pred.hh"
-#include "cpu/o3/btb.hh"
-#include "cpu/o3/ras.hh"
-#include "cpu/o3/tournament_pred.hh"
-#include "params/InOrderCPU.hh"
#include "cpu/inorder/inorder_dyn_inst.hh"
#include "cpu/inorder/pipeline_traits.hh"
-
-#include <list>
+#include "cpu/pred/2bit_local.hh"
+#include "cpu/pred/btb.hh"
+#include "cpu/pred/ras.hh"
+#include "cpu/pred/tournament.hh"
+#include "params/InOrderCPU.hh"
/**
* Basically a wrapper class to hold both the branch predictor
+++ /dev/null
-/*
- * Copyright (c) 2004-2006 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_2BIT_LOCAL_PRED_HH__
-#define __CPU_O3_2BIT_LOCAL_PRED_HH__
-
-#include <vector>
-
-#include "base/types.hh"
-#include "cpu/o3/sat_counter.hh"
-
-/**
- * Implements a local predictor that uses the PC to index into a table of
- * counters. Note that any time a pointer to the bp_history is given, it
- * should be NULL using this predictor because it does not have any branch
- * predictor state that needs to be recorded or updated; the update can be
- * determined solely by the branch being taken or not taken.
- */
-class LocalBP
-{
- public:
- /**
- * Default branch predictor constructor.
- * @param localPredictorSize Size of the local predictor.
- * @param localCtrBits Number of bits per counter.
- * @param instShiftAmt Offset amount for instructions to ignore alignment.
- */
- LocalBP(unsigned localPredictorSize, unsigned localCtrBits,
- unsigned instShiftAmt);
-
- /**
- * Looks up the given address in the branch predictor and returns
- * a true/false value as to whether it is taken.
- * @param branch_addr The address of the branch to look up.
- * @param bp_history Pointer to any bp history state.
- * @return Whether or not the branch is taken.
- */
- bool lookup(Addr &branch_addr, void * &bp_history);
-
- /**
- * Updates the branch predictor with the actual result of a branch.
- * @param branch_addr The address of the branch to update.
- * @param taken Whether or not the branch was taken.
- */
- void update(Addr &branch_addr, bool taken, void *bp_history);
-
- void squash(void *bp_history)
- { assert(bp_history == NULL); }
-
- void reset();
-
- private:
- /**
- * Returns the taken/not taken prediction given the value of the
- * counter.
- * @param count The value of the counter.
- * @return The prediction based on the counter value.
- */
- inline bool getPrediction(uint8_t &count);
-
- /** Calculates the local index based on the PC. */
- inline unsigned getLocalIndex(Addr &PC);
-
- /** Array of counters that make up the local predictor. */
- std::vector<SatCounter> localCtrs;
-
- /** Size of the local predictor. */
- unsigned localPredictorSize;
-
- /** Number of sets. */
- unsigned localPredictorSets;
-
- /** Number of bits of the local predictor's counters. */
- unsigned localCtrBits;
-
- /** Number of bits to shift the PC when calculating index. */
- unsigned instShiftAmt;
-
- /** Mask to get index bits. */
- unsigned indexMask;
-};
-
-#endif // __CPU_O3_2BIT_LOCAL_PRED_HH__
#include "base/statistics.hh"
#include "base/types.hh"
#include "cpu/inst_seq.hh"
-#include "cpu/o3/2bit_local_pred.hh"
-#include "cpu/o3/btb.hh"
-#include "cpu/o3/ras.hh"
-#include "cpu/o3/tournament_pred.hh"
+#include "cpu/pred/2bit_local.hh"
+#include "cpu/pred/btb.hh"
+#include "cpu/pred/ras.hh"
+#include "cpu/pred/tournament.hh"
class DerivO3CPUParams;
+++ /dev/null
-/*
- * 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_BTB_HH__
-#define __CPU_O3_BTB_HH__
-
-#include "base/misc.hh"
-#include "base/types.hh"
-
-class DefaultBTB
-{
- private:
- struct BTBEntry
- {
- BTBEntry()
- : tag(0), target(0), valid(false)
- {
- }
-
- /** The entry's tag. */
- Addr tag;
-
- /** The entry's target. */
- Addr target;
-
- /** The entry's thread id. */
- ThreadID tid;
-
- /** Whether or not the entry is valid. */
- bool valid;
- };
-
- public:
- /** Creates a BTB with the given number of entries, number of bits per
- * tag, and instruction offset amount.
- * @param numEntries Number of entries for the BTB.
- * @param tagBits Number of bits for each tag in the BTB.
- * @param instShiftAmt Offset amount for instructions to ignore alignment.
- */
- DefaultBTB(unsigned numEntries, unsigned tagBits,
- unsigned instShiftAmt);
-
- void reset();
-
- /** Looks up an address in the BTB. Must call valid() first on the address.
- * @param inst_PC The address of the branch to look up.
- * @param tid The thread id.
- * @return Returns the target of the branch.
- */
- Addr lookup(const Addr &inst_PC, ThreadID tid);
-
- /** Checks if a branch is in the BTB.
- * @param inst_PC The address of the branch to look up.
- * @param tid The thread id.
- * @return Whether or not the branch exists in the BTB.
- */
- bool valid(const Addr &inst_PC, ThreadID tid);
-
- /** Updates the BTB with the target of a branch.
- * @param inst_PC The address of the branch being updated.
- * @param target_PC The target address of the branch.
- * @param tid The thread id.
- */
- void update(const Addr &inst_PC, const Addr &target_PC,
- ThreadID tid);
-
- private:
- /** Returns the index into the BTB, based on the branch's PC.
- * @param inst_PC The branch to look up.
- * @return Returns the index into the BTB.
- */
- inline unsigned getIndex(const Addr &inst_PC);
-
- /** Returns the tag bits of a given address.
- * @param inst_PC The branch's address.
- * @return Returns the tag bits.
- */
- inline Addr getTag(const Addr &inst_PC);
-
- /** The actual BTB. */
- std::vector<BTBEntry> btb;
-
- /** The number of entries in the BTB. */
- unsigned numEntries;
-
- /** The index mask. */
- unsigned idxMask;
-
- /** The number of tag bits per entry. */
- unsigned tagBits;
-
- /** The tag mask. */
- unsigned tagMask;
-
- /** Number of bits to shift PC when calculating index. */
- unsigned instShiftAmt;
-
- /** Number of bits to shift PC when calculating tag. */
- unsigned tagShiftAmt;
-};
-
-#endif // __CPU_O3_BTB_HH__
+++ /dev/null
-/*
- * 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_RAS_HH__
-#define __CPU_O3_RAS_HH__
-
-#include <vector>
-
-#include "base/types.hh"
-
-/** Return address stack class, implements a simple RAS. */
-class ReturnAddrStack
-{
- public:
- /** Creates a return address stack, but init() must be called prior to
- * use.
- */
- ReturnAddrStack() {}
-
- /** Initializes RAS with a specified number of entries.
- * @param numEntries Number of entries in the RAS.
- */
- void init(unsigned numEntries);
-
- void reset();
-
- /** Returns the top address on the RAS. */
- Addr top()
- { return addrStack[tos]; }
-
- /** Returns the index of the top of the RAS. */
- unsigned topIdx()
- { return tos; }
-
- /** Pushes an address onto the RAS. */
- void push(const Addr &return_addr);
-
- /** Pops the top address from the RAS. */
- void pop();
-
- /** Changes index to the top of the RAS, and replaces the top address with
- * a new target.
- * @param top_entry_idx The index of the RAS that will now be the top.
- * @param restored_target The new target address of the new top of the RAS.
- */
- void restore(unsigned top_entry_idx, const Addr &restored_target);
-
- bool empty() { return usedEntries == 0; }
-
- bool full() { return usedEntries == numEntries; }
- private:
- /** Increments the top of stack index. */
- inline void incrTos()
- { if (++tos == numEntries) tos = 0; }
-
- /** Decrements the top of stack index. */
- inline void decrTos()
- { tos = (tos == 0 ? numEntries - 1 : tos - 1); }
-
- /** The RAS itself. */
- std::vector<Addr> addrStack;
-
- /** The number of entries in the RAS. */
- unsigned numEntries;
-
- /** The number of used entries in the RAS. */
- unsigned usedEntries;
-
- /** The top of stack index. */
- unsigned tos;
-};
-
-#endif // __CPU_O3_RAS_HH__
+++ /dev/null
-/*
- * Copyright (c) 2004-2006 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_TOURNAMENT_PRED_HH__
-#define __CPU_O3_TOURNAMENT_PRED_HH__
-
-#include <vector>
-
-#include "base/types.hh"
-#include "cpu/o3/sat_counter.hh"
-
-/**
- * Implements a tournament branch predictor, hopefully identical to the one
- * used in the 21264. It has a local predictor, which uses a local history
- * table to index into a table of counters, and a global predictor, which
- * uses a global history to index into a table of counters. A choice
- * predictor chooses between the two. Only the global history register
- * is speculatively updated, the rest are updated upon branches committing
- * or misspeculating.
- */
-class TournamentBP
-{
- public:
- /**
- * Default branch predictor constructor.
- */
- TournamentBP(unsigned localPredictorSize,
- unsigned localCtrBits,
- unsigned localHistoryTableSize,
- unsigned localHistoryBits,
- unsigned globalPredictorSize,
- unsigned globalHistoryBits,
- unsigned globalCtrBits,
- unsigned choicePredictorSize,
- unsigned choiceCtrBits,
- unsigned instShiftAmt);
-
- /**
- * Looks up the given address in the branch predictor and returns
- * a true/false value as to whether it is taken. Also creates a
- * BPHistory object to store any state it will need on squash/update.
- * @param branch_addr The address of the branch to look up.
- * @param bp_history Pointer that will be set to the BPHistory object.
- * @return Whether or not the branch is taken.
- */
- bool lookup(Addr &branch_addr, void * &bp_history);
-
- /**
- * Records that there was an unconditional branch, and modifies
- * the bp history to point to an object that has the previous
- * global history stored in it.
- * @param bp_history Pointer that will be set to the BPHistory object.
- */
- void uncondBr(void * &bp_history);
-
- /**
- * Updates the branch predictor with the actual result of a branch.
- * @param branch_addr The address of the branch to update.
- * @param taken Whether or not the branch was taken.
- * @param bp_history Pointer to the BPHistory object that was created
- * when the branch was predicted.
- */
- void update(Addr &branch_addr, bool taken, void *bp_history);
-
- /**
- * Restores the global branch history on a squash.
- * @param bp_history Pointer to the BPHistory object that has the
- * previous global branch history in it.
- */
- void squash(void *bp_history);
-
- /** Returns the global history. */
- inline unsigned readGlobalHist() { return globalHistory; }
-
- private:
- /**
- * Returns if the branch should be taken or not, given a counter
- * value.
- * @param count The counter value.
- */
- inline bool getPrediction(uint8_t &count);
-
- /**
- * Returns the local history index, given a branch address.
- * @param branch_addr The branch's PC address.
- */
- inline unsigned calcLocHistIdx(Addr &branch_addr);
-
- /** Updates global history as taken. */
- inline void updateGlobalHistTaken();
-
- /** Updates global history as not taken. */
- inline void updateGlobalHistNotTaken();
-
- /**
- * Updates local histories as taken.
- * @param local_history_idx The local history table entry that
- * will be updated.
- */
- inline void updateLocalHistTaken(unsigned local_history_idx);
-
- /**
- * Updates local histories as not taken.
- * @param local_history_idx The local history table entry that
- * will be updated.
- */
- inline void updateLocalHistNotTaken(unsigned local_history_idx);
-
- /**
- * The branch history information that is created upon predicting
- * a branch. It will be passed back upon updating and squashing,
- * when the BP can use this information to update/restore its
- * state properly.
- */
- struct BPHistory {
-#ifdef DEBUG
- BPHistory()
- { newCount++; }
- ~BPHistory()
- { newCount--; }
-
- static int newCount;
-#endif
- unsigned globalHistory;
- bool localPredTaken;
- bool globalPredTaken;
- bool globalUsed;
- };
-
- /** Local counters. */
- std::vector<SatCounter> localCtrs;
-
- /** Size of the local predictor. */
- unsigned localPredictorSize;
-
- /** Mask to get the proper index bits into the predictor. */
- unsigned localPredictorMask;
-
- /** Number of bits of the local predictor's counters. */
- unsigned localCtrBits;
-
- /** Array of local history table entries. */
- std::vector<unsigned> localHistoryTable;
-
- /** Size of the local history table. */
- unsigned localHistoryTableSize;
-
- /** Number of bits for each entry of the local history table.
- * @todo Doesn't this come from the size of the local predictor?
- */
- unsigned localHistoryBits;
-
- /** Mask to get the proper local history. */
- unsigned localHistoryMask;
-
- /** Array of counters that make up the global predictor. */
- std::vector<SatCounter> globalCtrs;
-
- /** Size of the global predictor. */
- unsigned globalPredictorSize;
-
- /** Number of bits of the global predictor's counters. */
- unsigned globalCtrBits;
-
- /** Global history register. */
- unsigned globalHistory;
-
- /** Number of bits for the global history. */
- unsigned globalHistoryBits;
-
- /** Mask to get the proper global history. */
- unsigned globalHistoryMask;
-
- /** Array of counters that make up the choice predictor. */
- std::vector<SatCounter> choiceCtrs;
-
- /** Size of the choice predictor (identical to the global predictor). */
- unsigned choicePredictorSize;
-
- /** Number of bits of the choice predictor's counters. */
- unsigned choiceCtrBits;
-
- /** Number of bits to shift the instruction over to get rid of the word
- * offset.
- */
- unsigned instShiftAmt;
-
- /** Threshold for the counter value; above the threshold is taken,
- * equal to or below the threshold is not taken.
- */
- unsigned threshold;
-};
-
-#endif // __CPU_O3_TOURNAMENT_PRED_HH__
--- /dev/null
+/*
+ * Copyright (c) 2004-2006 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
+ */
+
+#include "base/intmath.hh"
+#include "base/misc.hh"
+#include "base/trace.hh"
+#include "cpu/pred/2bit_local.hh"
+
+LocalBP::LocalBP(unsigned _localPredictorSize,
+ unsigned _localCtrBits,
+ unsigned _instShiftAmt)
+ : localPredictorSize(_localPredictorSize),
+ localCtrBits(_localCtrBits),
+ instShiftAmt(_instShiftAmt)
+{
+ if (!isPowerOf2(localPredictorSize)) {
+ fatal("Invalid local predictor size!\n");
+ }
+
+ localPredictorSets = localPredictorSize / localCtrBits;
+
+ if (!isPowerOf2(localPredictorSets)) {
+ fatal("Invalid number of local predictor sets! Check localCtrBits.\n");
+ }
+
+ // Setup the index mask.
+ indexMask = localPredictorSets - 1;
+
+ DPRINTF(Fetch, "Branch predictor: index mask: %#x\n", indexMask);
+
+ // Setup the array of counters for the local predictor.
+ localCtrs.resize(localPredictorSets);
+
+ for (int i = 0; i < localPredictorSets; ++i)
+ localCtrs[i].setBits(_localCtrBits);
+
+ DPRINTF(Fetch, "Branch predictor: local predictor size: %i\n",
+ localPredictorSize);
+
+ DPRINTF(Fetch, "Branch predictor: local counter bits: %i\n", localCtrBits);
+
+ DPRINTF(Fetch, "Branch predictor: instruction shift amount: %i\n",
+ instShiftAmt);
+}
+
+void
+LocalBP::reset()
+{
+ for (int i = 0; i < localPredictorSets; ++i) {
+ localCtrs[i].reset();
+ }
+}
+
+bool
+LocalBP::lookup(Addr &branch_addr, void * &bp_history)
+{
+ bool taken;
+ uint8_t counter_val;
+ unsigned local_predictor_idx = getLocalIndex(branch_addr);
+
+ DPRINTF(Fetch, "Branch predictor: Looking up index %#x\n",
+ local_predictor_idx);
+
+ counter_val = localCtrs[local_predictor_idx].read();
+
+ DPRINTF(Fetch, "Branch predictor: prediction is %i.\n",
+ (int)counter_val);
+
+ taken = getPrediction(counter_val);
+
+#if 0
+ // Speculative update.
+ if (taken) {
+ DPRINTF(Fetch, "Branch predictor: Branch updated as taken.\n");
+ localCtrs[local_predictor_idx].increment();
+ } else {
+ DPRINTF(Fetch, "Branch predictor: Branch updated as not taken.\n");
+ localCtrs[local_predictor_idx].decrement();
+ }
+#endif
+
+ return taken;
+}
+
+void
+LocalBP::update(Addr &branch_addr, bool taken, void *bp_history)
+{
+ assert(bp_history == NULL);
+ unsigned local_predictor_idx;
+
+ // Update the local predictor.
+ local_predictor_idx = getLocalIndex(branch_addr);
+
+ DPRINTF(Fetch, "Branch predictor: Looking up index %#x\n",
+ local_predictor_idx);
+
+ if (taken) {
+ DPRINTF(Fetch, "Branch predictor: Branch updated as taken.\n");
+ localCtrs[local_predictor_idx].increment();
+ } else {
+ DPRINTF(Fetch, "Branch predictor: Branch updated as not taken.\n");
+ localCtrs[local_predictor_idx].decrement();
+ }
+}
+
+inline
+bool
+LocalBP::getPrediction(uint8_t &count)
+{
+ // Get the MSB of the count
+ return (count >> (localCtrBits - 1));
+}
+
+inline
+unsigned
+LocalBP::getLocalIndex(Addr &branch_addr)
+{
+ return (branch_addr >> instShiftAmt) & indexMask;
+}
--- /dev/null
+/*
+ * Copyright (c) 2004-2006 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_2BIT_LOCAL_PRED_HH__
+#define __CPU_O3_2BIT_LOCAL_PRED_HH__
+
+#include <vector>
+
+#include "base/types.hh"
+#include "cpu/o3/sat_counter.hh"
+
+/**
+ * Implements a local predictor that uses the PC to index into a table of
+ * counters. Note that any time a pointer to the bp_history is given, it
+ * should be NULL using this predictor because it does not have any branch
+ * predictor state that needs to be recorded or updated; the update can be
+ * determined solely by the branch being taken or not taken.
+ */
+class LocalBP
+{
+ public:
+ /**
+ * Default branch predictor constructor.
+ * @param localPredictorSize Size of the local predictor.
+ * @param localCtrBits Number of bits per counter.
+ * @param instShiftAmt Offset amount for instructions to ignore alignment.
+ */
+ LocalBP(unsigned localPredictorSize, unsigned localCtrBits,
+ unsigned instShiftAmt);
+
+ /**
+ * Looks up the given address in the branch predictor and returns
+ * a true/false value as to whether it is taken.
+ * @param branch_addr The address of the branch to look up.
+ * @param bp_history Pointer to any bp history state.
+ * @return Whether or not the branch is taken.
+ */
+ bool lookup(Addr &branch_addr, void * &bp_history);
+
+ /**
+ * Updates the branch predictor with the actual result of a branch.
+ * @param branch_addr The address of the branch to update.
+ * @param taken Whether or not the branch was taken.
+ */
+ void update(Addr &branch_addr, bool taken, void *bp_history);
+
+ void squash(void *bp_history)
+ { assert(bp_history == NULL); }
+
+ void reset();
+
+ private:
+ /**
+ * Returns the taken/not taken prediction given the value of the
+ * counter.
+ * @param count The value of the counter.
+ * @return The prediction based on the counter value.
+ */
+ inline bool getPrediction(uint8_t &count);
+
+ /** Calculates the local index based on the PC. */
+ inline unsigned getLocalIndex(Addr &PC);
+
+ /** Array of counters that make up the local predictor. */
+ std::vector<SatCounter> localCtrs;
+
+ /** Size of the local predictor. */
+ unsigned localPredictorSize;
+
+ /** Number of sets. */
+ unsigned localPredictorSets;
+
+ /** Number of bits of the local predictor's counters. */
+ unsigned localCtrBits;
+
+ /** Number of bits to shift the PC when calculating index. */
+ unsigned instShiftAmt;
+
+ /** Mask to get index bits. */
+ unsigned indexMask;
+};
+
+#endif // __CPU_O3_2BIT_LOCAL_PRED_HH__
--- /dev/null
+# -*- mode:python -*-
+
+# 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: Steve Reinhardt
+
+Import('*')
+
+if 'InOrderCPU' in env['CPU_MODELS'] or 'O3CPU' in env['CPU_MODELS']:
+ Source('2bit_local.cc')
+ Source('btb.cc')
+ Source('ras.cc')
+ Source('tournament.cc')
+ TraceFlag('FreeList')
--- /dev/null
+/*
+ * 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
+ */
+
+#include "base/intmath.hh"
+#include "base/trace.hh"
+#include "cpu/pred/btb.hh"
+
+DefaultBTB::DefaultBTB(unsigned _numEntries,
+ unsigned _tagBits,
+ unsigned _instShiftAmt)
+ : numEntries(_numEntries),
+ tagBits(_tagBits),
+ instShiftAmt(_instShiftAmt)
+{
+ DPRINTF(Fetch, "BTB: Creating BTB object.\n");
+
+ if (!isPowerOf2(numEntries)) {
+ fatal("BTB entries is not a power of 2!");
+ }
+
+ btb.resize(numEntries);
+
+ for (int i = 0; i < numEntries; ++i) {
+ btb[i].valid = false;
+ }
+
+ idxMask = numEntries - 1;
+
+ tagMask = (1 << tagBits) - 1;
+
+ tagShiftAmt = instShiftAmt + floorLog2(numEntries);
+}
+
+void
+DefaultBTB::reset()
+{
+ for (int i = 0; i < numEntries; ++i) {
+ btb[i].valid = false;
+ }
+}
+
+inline
+unsigned
+DefaultBTB::getIndex(const Addr &inst_PC)
+{
+ // Need to shift PC over by the word offset.
+ return (inst_PC >> instShiftAmt) & idxMask;
+}
+
+inline
+Addr
+DefaultBTB::getTag(const Addr &inst_PC)
+{
+ return (inst_PC >> tagShiftAmt) & tagMask;
+}
+
+bool
+DefaultBTB::valid(const Addr &inst_PC, ThreadID tid)
+{
+ unsigned btb_idx = getIndex(inst_PC);
+
+ Addr inst_tag = getTag(inst_PC);
+
+ assert(btb_idx < numEntries);
+
+ if (btb[btb_idx].valid
+ && inst_tag == btb[btb_idx].tag
+ && btb[btb_idx].tid == tid) {
+ return true;
+ } else {
+ return false;
+ }
+}
+
+// @todo Create some sort of return struct that has both whether or not the
+// address is valid, and also the address. For now will just use addr = 0 to
+// represent invalid entry.
+Addr
+DefaultBTB::lookup(const Addr &inst_PC, ThreadID tid)
+{
+ unsigned btb_idx = getIndex(inst_PC);
+
+ Addr inst_tag = getTag(inst_PC);
+
+ assert(btb_idx < numEntries);
+
+ if (btb[btb_idx].valid
+ && inst_tag == btb[btb_idx].tag
+ && btb[btb_idx].tid == tid) {
+ return btb[btb_idx].target;
+ } else {
+ return 0;
+ }
+}
+
+void
+DefaultBTB::update(const Addr &inst_PC, const Addr &target, ThreadID tid)
+{
+ unsigned btb_idx = getIndex(inst_PC);
+
+ assert(btb_idx < numEntries);
+
+ btb[btb_idx].tid = tid;
+ btb[btb_idx].valid = true;
+ btb[btb_idx].target = target;
+ btb[btb_idx].tag = getTag(inst_PC);
+}
--- /dev/null
+/*
+ * 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_BTB_HH__
+#define __CPU_O3_BTB_HH__
+
+#include "base/misc.hh"
+#include "base/types.hh"
+
+class DefaultBTB
+{
+ private:
+ struct BTBEntry
+ {
+ BTBEntry()
+ : tag(0), target(0), valid(false)
+ {
+ }
+
+ /** The entry's tag. */
+ Addr tag;
+
+ /** The entry's target. */
+ Addr target;
+
+ /** The entry's thread id. */
+ ThreadID tid;
+
+ /** Whether or not the entry is valid. */
+ bool valid;
+ };
+
+ public:
+ /** Creates a BTB with the given number of entries, number of bits per
+ * tag, and instruction offset amount.
+ * @param numEntries Number of entries for the BTB.
+ * @param tagBits Number of bits for each tag in the BTB.
+ * @param instShiftAmt Offset amount for instructions to ignore alignment.
+ */
+ DefaultBTB(unsigned numEntries, unsigned tagBits,
+ unsigned instShiftAmt);
+
+ void reset();
+
+ /** Looks up an address in the BTB. Must call valid() first on the address.
+ * @param inst_PC The address of the branch to look up.
+ * @param tid The thread id.
+ * @return Returns the target of the branch.
+ */
+ Addr lookup(const Addr &inst_PC, ThreadID tid);
+
+ /** Checks if a branch is in the BTB.
+ * @param inst_PC The address of the branch to look up.
+ * @param tid The thread id.
+ * @return Whether or not the branch exists in the BTB.
+ */
+ bool valid(const Addr &inst_PC, ThreadID tid);
+
+ /** Updates the BTB with the target of a branch.
+ * @param inst_PC The address of the branch being updated.
+ * @param target_PC The target address of the branch.
+ * @param tid The thread id.
+ */
+ void update(const Addr &inst_PC, const Addr &target_PC,
+ ThreadID tid);
+
+ private:
+ /** Returns the index into the BTB, based on the branch's PC.
+ * @param inst_PC The branch to look up.
+ * @return Returns the index into the BTB.
+ */
+ inline unsigned getIndex(const Addr &inst_PC);
+
+ /** Returns the tag bits of a given address.
+ * @param inst_PC The branch's address.
+ * @return Returns the tag bits.
+ */
+ inline Addr getTag(const Addr &inst_PC);
+
+ /** The actual BTB. */
+ std::vector<BTBEntry> btb;
+
+ /** The number of entries in the BTB. */
+ unsigned numEntries;
+
+ /** The index mask. */
+ unsigned idxMask;
+
+ /** The number of tag bits per entry. */
+ unsigned tagBits;
+
+ /** The tag mask. */
+ unsigned tagMask;
+
+ /** Number of bits to shift PC when calculating index. */
+ unsigned instShiftAmt;
+
+ /** Number of bits to shift PC when calculating tag. */
+ unsigned tagShiftAmt;
+};
+
+#endif // __CPU_O3_BTB_HH__
--- /dev/null
+/*
+ * 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
+ */
+
+#include "cpu/pred/ras.hh"
+
+void
+ReturnAddrStack::init(unsigned _numEntries)
+{
+ numEntries = _numEntries;
+ usedEntries = 0;
+ tos = 0;
+
+ addrStack.resize(numEntries);
+
+ for (int i = 0; i < numEntries; ++i)
+ addrStack[i] = 0;
+}
+
+void
+ReturnAddrStack::reset()
+{
+ usedEntries = 0;
+ tos = 0;
+ for (int i = 0; i < numEntries; ++i)
+ addrStack[i] = 0;
+}
+
+void
+ReturnAddrStack::push(const Addr &return_addr)
+{
+ incrTos();
+
+ addrStack[tos] = return_addr;
+
+ if (usedEntries != numEntries) {
+ ++usedEntries;
+ }
+}
+
+void
+ReturnAddrStack::pop()
+{
+ if (usedEntries > 0) {
+ --usedEntries;
+ }
+
+ decrTos();
+}
+
+void
+ReturnAddrStack::restore(unsigned top_entry_idx,
+ const Addr &restored_target)
+{
+ tos = top_entry_idx;
+
+ addrStack[tos] = restored_target;
+}
--- /dev/null
+/*
+ * 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_RAS_HH__
+#define __CPU_O3_RAS_HH__
+
+#include <vector>
+
+#include "base/types.hh"
+
+/** Return address stack class, implements a simple RAS. */
+class ReturnAddrStack
+{
+ public:
+ /** Creates a return address stack, but init() must be called prior to
+ * use.
+ */
+ ReturnAddrStack() {}
+
+ /** Initializes RAS with a specified number of entries.
+ * @param numEntries Number of entries in the RAS.
+ */
+ void init(unsigned numEntries);
+
+ void reset();
+
+ /** Returns the top address on the RAS. */
+ Addr top()
+ { return addrStack[tos]; }
+
+ /** Returns the index of the top of the RAS. */
+ unsigned topIdx()
+ { return tos; }
+
+ /** Pushes an address onto the RAS. */
+ void push(const Addr &return_addr);
+
+ /** Pops the top address from the RAS. */
+ void pop();
+
+ /** Changes index to the top of the RAS, and replaces the top address with
+ * a new target.
+ * @param top_entry_idx The index of the RAS that will now be the top.
+ * @param restored_target The new target address of the new top of the RAS.
+ */
+ void restore(unsigned top_entry_idx, const Addr &restored_target);
+
+ bool empty() { return usedEntries == 0; }
+
+ bool full() { return usedEntries == numEntries; }
+ private:
+ /** Increments the top of stack index. */
+ inline void incrTos()
+ { if (++tos == numEntries) tos = 0; }
+
+ /** Decrements the top of stack index. */
+ inline void decrTos()
+ { tos = (tos == 0 ? numEntries - 1 : tos - 1); }
+
+ /** The RAS itself. */
+ std::vector<Addr> addrStack;
+
+ /** The number of entries in the RAS. */
+ unsigned numEntries;
+
+ /** The number of used entries in the RAS. */
+ unsigned usedEntries;
+
+ /** The top of stack index. */
+ unsigned tos;
+};
+
+#endif // __CPU_O3_RAS_HH__
--- /dev/null
+/*
+ * Copyright (c) 2004-2006 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
+ */
+
+#include "base/intmath.hh"
+#include "cpu/pred/tournament.hh"
+
+TournamentBP::TournamentBP(unsigned _localPredictorSize,
+ unsigned _localCtrBits,
+ unsigned _localHistoryTableSize,
+ unsigned _localHistoryBits,
+ unsigned _globalPredictorSize,
+ unsigned _globalCtrBits,
+ unsigned _globalHistoryBits,
+ unsigned _choicePredictorSize,
+ unsigned _choiceCtrBits,
+ unsigned _instShiftAmt)
+ : localPredictorSize(_localPredictorSize),
+ localCtrBits(_localCtrBits),
+ localHistoryTableSize(_localHistoryTableSize),
+ localHistoryBits(_localHistoryBits),
+ globalPredictorSize(_globalPredictorSize),
+ globalCtrBits(_globalCtrBits),
+ globalHistoryBits(_globalHistoryBits),
+ choicePredictorSize(_globalPredictorSize),
+ choiceCtrBits(_choiceCtrBits),
+ instShiftAmt(_instShiftAmt)
+{
+ if (!isPowerOf2(localPredictorSize)) {
+ fatal("Invalid local predictor size!\n");
+ }
+
+ //Setup the array of counters for the local predictor
+ localCtrs.resize(localPredictorSize);
+
+ for (int i = 0; i < localPredictorSize; ++i)
+ localCtrs[i].setBits(localCtrBits);
+
+ localPredictorMask = floorPow2(localPredictorSize) - 1;
+
+ if (!isPowerOf2(localHistoryTableSize)) {
+ fatal("Invalid local history table size!\n");
+ }
+
+ //Setup the history table for the local table
+ localHistoryTable.resize(localHistoryTableSize);
+
+ for (int i = 0; i < localHistoryTableSize; ++i)
+ localHistoryTable[i] = 0;
+
+ // Setup the local history mask
+ localHistoryMask = (1 << localHistoryBits) - 1;
+
+ if (!isPowerOf2(globalPredictorSize)) {
+ fatal("Invalid global predictor size!\n");
+ }
+
+ //Setup the array of counters for the global predictor
+ globalCtrs.resize(globalPredictorSize);
+
+ for (int i = 0; i < globalPredictorSize; ++i)
+ globalCtrs[i].setBits(globalCtrBits);
+
+ //Clear the global history
+ globalHistory = 0;
+ // Setup the global history mask
+ globalHistoryMask = (1 << globalHistoryBits) - 1;
+
+ if (!isPowerOf2(choicePredictorSize)) {
+ fatal("Invalid choice predictor size!\n");
+ }
+
+ //Setup the array of counters for the choice predictor
+ choiceCtrs.resize(choicePredictorSize);
+
+ for (int i = 0; i < choicePredictorSize; ++i)
+ choiceCtrs[i].setBits(choiceCtrBits);
+
+ // @todo: Allow for different thresholds between the predictors.
+ threshold = (1 << (localCtrBits - 1)) - 1;
+ threshold = threshold / 2;
+}
+
+inline
+unsigned
+TournamentBP::calcLocHistIdx(Addr &branch_addr)
+{
+ // Get low order bits after removing instruction offset.
+ return (branch_addr >> instShiftAmt) & (localHistoryTableSize - 1);
+}
+
+inline
+void
+TournamentBP::updateGlobalHistTaken()
+{
+ globalHistory = (globalHistory << 1) | 1;
+ globalHistory = globalHistory & globalHistoryMask;
+}
+
+inline
+void
+TournamentBP::updateGlobalHistNotTaken()
+{
+ globalHistory = (globalHistory << 1);
+ globalHistory = globalHistory & globalHistoryMask;
+}
+
+inline
+void
+TournamentBP::updateLocalHistTaken(unsigned local_history_idx)
+{
+ localHistoryTable[local_history_idx] =
+ (localHistoryTable[local_history_idx] << 1) | 1;
+}
+
+inline
+void
+TournamentBP::updateLocalHistNotTaken(unsigned local_history_idx)
+{
+ localHistoryTable[local_history_idx] =
+ (localHistoryTable[local_history_idx] << 1);
+}
+
+bool
+TournamentBP::lookup(Addr &branch_addr, void * &bp_history)
+{
+ bool local_prediction;
+ unsigned local_history_idx;
+ unsigned local_predictor_idx;
+
+ bool global_prediction;
+ bool choice_prediction;
+
+ //Lookup in the local predictor to get its branch prediction
+ local_history_idx = calcLocHistIdx(branch_addr);
+ local_predictor_idx = localHistoryTable[local_history_idx]
+ & localPredictorMask;
+ local_prediction = localCtrs[local_predictor_idx].read() > threshold;
+
+ //Lookup in the global predictor to get its branch prediction
+ global_prediction = globalCtrs[globalHistory].read() > threshold;
+
+ //Lookup in the choice predictor to see which one to use
+ choice_prediction = choiceCtrs[globalHistory].read() > threshold;
+
+ // Create BPHistory and pass it back to be recorded.
+ BPHistory *history = new BPHistory;
+ history->globalHistory = globalHistory;
+ history->localPredTaken = local_prediction;
+ history->globalPredTaken = global_prediction;
+ history->globalUsed = choice_prediction;
+ bp_history = (void *)history;
+
+ assert(globalHistory < globalPredictorSize &&
+ local_history_idx < localHistoryTableSize &&
+ local_predictor_idx < localPredictorSize);
+
+ // Commented code is for doing speculative update of counters and
+ // all histories.
+ if (choice_prediction) {
+ if (global_prediction) {
+// updateHistoriesTaken(local_history_idx);
+// globalCtrs[globalHistory].increment();
+// localCtrs[local_history_idx].increment();
+ updateGlobalHistTaken();
+ return true;
+ } else {
+// updateHistoriesNotTaken(local_history_idx);
+// globalCtrs[globalHistory].decrement();
+// localCtrs[local_history_idx].decrement();
+ updateGlobalHistNotTaken();
+ return false;
+ }
+ } else {
+ if (local_prediction) {
+// updateHistoriesTaken(local_history_idx);
+// globalCtrs[globalHistory].increment();
+// localCtrs[local_history_idx].increment();
+ updateGlobalHistTaken();
+ return true;
+ } else {
+// updateHistoriesNotTaken(local_history_idx);
+// globalCtrs[globalHistory].decrement();
+// localCtrs[local_history_idx].decrement();
+ updateGlobalHistNotTaken();
+ return false;
+ }
+ }
+}
+
+void
+TournamentBP::uncondBr(void * &bp_history)
+{
+ // Create BPHistory and pass it back to be recorded.
+ BPHistory *history = new BPHistory;
+ history->globalHistory = globalHistory;
+ history->localPredTaken = true;
+ history->globalPredTaken = true;
+ bp_history = static_cast<void *>(history);
+
+ updateGlobalHistTaken();
+}
+
+void
+TournamentBP::update(Addr &branch_addr, bool taken, void *bp_history)
+{
+ unsigned local_history_idx;
+ unsigned local_predictor_idx;
+ unsigned local_predictor_hist;
+
+ // Get the local predictor's current prediction
+ local_history_idx = calcLocHistIdx(branch_addr);
+ local_predictor_hist = localHistoryTable[local_history_idx];
+ local_predictor_idx = local_predictor_hist & localPredictorMask;
+
+ // Update the choice predictor to tell it which one was correct if
+ // there was a prediction.
+ if (bp_history) {
+ BPHistory *history = static_cast<BPHistory *>(bp_history);
+ if (history->localPredTaken != history->globalPredTaken) {
+ // If the local prediction matches the actual outcome,
+ // decerement the counter. Otherwise increment the
+ // counter.
+ if (history->localPredTaken == taken) {
+ choiceCtrs[globalHistory].decrement();
+ } else if (history->globalPredTaken == taken){
+ choiceCtrs[globalHistory].increment();
+ }
+ }
+
+ // We're done with this history, now delete it.
+ delete history;
+ }
+
+ assert(globalHistory < globalPredictorSize &&
+ local_history_idx < localHistoryTableSize &&
+ local_predictor_idx < localPredictorSize);
+
+ // Update the counters and local history with the proper
+ // resolution of the branch. Global history is updated
+ // speculatively and restored upon squash() calls, so it does not
+ // need to be updated.
+ if (taken) {
+ localCtrs[local_predictor_idx].increment();
+ globalCtrs[globalHistory].increment();
+
+ updateLocalHistTaken(local_history_idx);
+ } else {
+ localCtrs[local_predictor_idx].decrement();
+ globalCtrs[globalHistory].decrement();
+
+ updateLocalHistNotTaken(local_history_idx);
+ }
+}
+
+void
+TournamentBP::squash(void *bp_history)
+{
+ BPHistory *history = static_cast<BPHistory *>(bp_history);
+
+ // Restore global history to state prior to this branch.
+ globalHistory = history->globalHistory;
+
+ // Delete this BPHistory now that we're done with it.
+ delete history;
+}
+
+#ifdef DEBUG
+int
+TournamentBP::BPHistory::newCount = 0;
+#endif
--- /dev/null
+/*
+ * Copyright (c) 2004-2006 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_TOURNAMENT_PRED_HH__
+#define __CPU_O3_TOURNAMENT_PRED_HH__
+
+#include <vector>
+
+#include "base/types.hh"
+#include "cpu/o3/sat_counter.hh"
+
+/**
+ * Implements a tournament branch predictor, hopefully identical to the one
+ * used in the 21264. It has a local predictor, which uses a local history
+ * table to index into a table of counters, and a global predictor, which
+ * uses a global history to index into a table of counters. A choice
+ * predictor chooses between the two. Only the global history register
+ * is speculatively updated, the rest are updated upon branches committing
+ * or misspeculating.
+ */
+class TournamentBP
+{
+ public:
+ /**
+ * Default branch predictor constructor.
+ */
+ TournamentBP(unsigned localPredictorSize,
+ unsigned localCtrBits,
+ unsigned localHistoryTableSize,
+ unsigned localHistoryBits,
+ unsigned globalPredictorSize,
+ unsigned globalHistoryBits,
+ unsigned globalCtrBits,
+ unsigned choicePredictorSize,
+ unsigned choiceCtrBits,
+ unsigned instShiftAmt);
+
+ /**
+ * Looks up the given address in the branch predictor and returns
+ * a true/false value as to whether it is taken. Also creates a
+ * BPHistory object to store any state it will need on squash/update.
+ * @param branch_addr The address of the branch to look up.
+ * @param bp_history Pointer that will be set to the BPHistory object.
+ * @return Whether or not the branch is taken.
+ */
+ bool lookup(Addr &branch_addr, void * &bp_history);
+
+ /**
+ * Records that there was an unconditional branch, and modifies
+ * the bp history to point to an object that has the previous
+ * global history stored in it.
+ * @param bp_history Pointer that will be set to the BPHistory object.
+ */
+ void uncondBr(void * &bp_history);
+
+ /**
+ * Updates the branch predictor with the actual result of a branch.
+ * @param branch_addr The address of the branch to update.
+ * @param taken Whether or not the branch was taken.
+ * @param bp_history Pointer to the BPHistory object that was created
+ * when the branch was predicted.
+ */
+ void update(Addr &branch_addr, bool taken, void *bp_history);
+
+ /**
+ * Restores the global branch history on a squash.
+ * @param bp_history Pointer to the BPHistory object that has the
+ * previous global branch history in it.
+ */
+ void squash(void *bp_history);
+
+ /** Returns the global history. */
+ inline unsigned readGlobalHist() { return globalHistory; }
+
+ private:
+ /**
+ * Returns if the branch should be taken or not, given a counter
+ * value.
+ * @param count The counter value.
+ */
+ inline bool getPrediction(uint8_t &count);
+
+ /**
+ * Returns the local history index, given a branch address.
+ * @param branch_addr The branch's PC address.
+ */
+ inline unsigned calcLocHistIdx(Addr &branch_addr);
+
+ /** Updates global history as taken. */
+ inline void updateGlobalHistTaken();
+
+ /** Updates global history as not taken. */
+ inline void updateGlobalHistNotTaken();
+
+ /**
+ * Updates local histories as taken.
+ * @param local_history_idx The local history table entry that
+ * will be updated.
+ */
+ inline void updateLocalHistTaken(unsigned local_history_idx);
+
+ /**
+ * Updates local histories as not taken.
+ * @param local_history_idx The local history table entry that
+ * will be updated.
+ */
+ inline void updateLocalHistNotTaken(unsigned local_history_idx);
+
+ /**
+ * The branch history information that is created upon predicting
+ * a branch. It will be passed back upon updating and squashing,
+ * when the BP can use this information to update/restore its
+ * state properly.
+ */
+ struct BPHistory {
+#ifdef DEBUG
+ BPHistory()
+ { newCount++; }
+ ~BPHistory()
+ { newCount--; }
+
+ static int newCount;
+#endif
+ unsigned globalHistory;
+ bool localPredTaken;
+ bool globalPredTaken;
+ bool globalUsed;
+ };
+
+ /** Local counters. */
+ std::vector<SatCounter> localCtrs;
+
+ /** Size of the local predictor. */
+ unsigned localPredictorSize;
+
+ /** Mask to get the proper index bits into the predictor. */
+ unsigned localPredictorMask;
+
+ /** Number of bits of the local predictor's counters. */
+ unsigned localCtrBits;
+
+ /** Array of local history table entries. */
+ std::vector<unsigned> localHistoryTable;
+
+ /** Size of the local history table. */
+ unsigned localHistoryTableSize;
+
+ /** Number of bits for each entry of the local history table.
+ * @todo Doesn't this come from the size of the local predictor?
+ */
+ unsigned localHistoryBits;
+
+ /** Mask to get the proper local history. */
+ unsigned localHistoryMask;
+
+ /** Array of counters that make up the global predictor. */
+ std::vector<SatCounter> globalCtrs;
+
+ /** Size of the global predictor. */
+ unsigned globalPredictorSize;
+
+ /** Number of bits of the global predictor's counters. */
+ unsigned globalCtrBits;
+
+ /** Global history register. */
+ unsigned globalHistory;
+
+ /** Number of bits for the global history. */
+ unsigned globalHistoryBits;
+
+ /** Mask to get the proper global history. */
+ unsigned globalHistoryMask;
+
+ /** Array of counters that make up the choice predictor. */
+ std::vector<SatCounter> choiceCtrs;
+
+ /** Size of the choice predictor (identical to the global predictor). */
+ unsigned choicePredictorSize;
+
+ /** Number of bits of the choice predictor's counters. */
+ unsigned choiceCtrBits;
+
+ /** Number of bits to shift the instruction over to get rid of the word
+ * offset.
+ */
+ unsigned instShiftAmt;
+
+ /** Threshold for the counter value; above the threshold is taken,
+ * equal to or below the threshold is not taken.
+ */
+ unsigned threshold;
+};
+
+#endif // __CPU_O3_TOURNAMENT_PRED_HH__
+++ /dev/null
-/*
- * 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
- */
-
-#include "cpu/o3/ras.hh"
-
-void
-ReturnAddrStack::init(unsigned _numEntries)
-{
- numEntries = _numEntries;
- usedEntries = 0;
- tos = 0;
-
- addrStack.resize(numEntries);
-
- for (int i = 0; i < numEntries; ++i)
- addrStack[i] = 0;
-}
-
-void
-ReturnAddrStack::reset()
-{
- usedEntries = 0;
- tos = 0;
- for (int i = 0; i < numEntries; ++i)
- addrStack[i] = 0;
-}
-
-void
-ReturnAddrStack::push(const Addr &return_addr)
-{
- incrTos();
-
- addrStack[tos] = return_addr;
-
- if (usedEntries != numEntries) {
- ++usedEntries;
- }
-}
-
-void
-ReturnAddrStack::pop()
-{
- if (usedEntries > 0) {
- --usedEntries;
- }
-
- decrTos();
-}
-
-void
-ReturnAddrStack::restore(unsigned top_entry_idx,
- const Addr &restored_target)
-{
- tos = top_entry_idx;
-
- addrStack[tos] = restored_target;
-}
+++ /dev/null
-/*
- * Copyright (c) 2004-2006 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
- */
-
-#include "base/intmath.hh"
-#include "cpu/o3/tournament_pred.hh"
-
-TournamentBP::TournamentBP(unsigned _localPredictorSize,
- unsigned _localCtrBits,
- unsigned _localHistoryTableSize,
- unsigned _localHistoryBits,
- unsigned _globalPredictorSize,
- unsigned _globalCtrBits,
- unsigned _globalHistoryBits,
- unsigned _choicePredictorSize,
- unsigned _choiceCtrBits,
- unsigned _instShiftAmt)
- : localPredictorSize(_localPredictorSize),
- localCtrBits(_localCtrBits),
- localHistoryTableSize(_localHistoryTableSize),
- localHistoryBits(_localHistoryBits),
- globalPredictorSize(_globalPredictorSize),
- globalCtrBits(_globalCtrBits),
- globalHistoryBits(_globalHistoryBits),
- choicePredictorSize(_globalPredictorSize),
- choiceCtrBits(_choiceCtrBits),
- instShiftAmt(_instShiftAmt)
-{
- if (!isPowerOf2(localPredictorSize)) {
- fatal("Invalid local predictor size!\n");
- }
-
- //Setup the array of counters for the local predictor
- localCtrs.resize(localPredictorSize);
-
- for (int i = 0; i < localPredictorSize; ++i)
- localCtrs[i].setBits(localCtrBits);
-
- localPredictorMask = floorPow2(localPredictorSize) - 1;
-
- if (!isPowerOf2(localHistoryTableSize)) {
- fatal("Invalid local history table size!\n");
- }
-
- //Setup the history table for the local table
- localHistoryTable.resize(localHistoryTableSize);
-
- for (int i = 0; i < localHistoryTableSize; ++i)
- localHistoryTable[i] = 0;
-
- // Setup the local history mask
- localHistoryMask = (1 << localHistoryBits) - 1;
-
- if (!isPowerOf2(globalPredictorSize)) {
- fatal("Invalid global predictor size!\n");
- }
-
- //Setup the array of counters for the global predictor
- globalCtrs.resize(globalPredictorSize);
-
- for (int i = 0; i < globalPredictorSize; ++i)
- globalCtrs[i].setBits(globalCtrBits);
-
- //Clear the global history
- globalHistory = 0;
- // Setup the global history mask
- globalHistoryMask = (1 << globalHistoryBits) - 1;
-
- if (!isPowerOf2(choicePredictorSize)) {
- fatal("Invalid choice predictor size!\n");
- }
-
- //Setup the array of counters for the choice predictor
- choiceCtrs.resize(choicePredictorSize);
-
- for (int i = 0; i < choicePredictorSize; ++i)
- choiceCtrs[i].setBits(choiceCtrBits);
-
- // @todo: Allow for different thresholds between the predictors.
- threshold = (1 << (localCtrBits - 1)) - 1;
- threshold = threshold / 2;
-}
-
-inline
-unsigned
-TournamentBP::calcLocHistIdx(Addr &branch_addr)
-{
- // Get low order bits after removing instruction offset.
- return (branch_addr >> instShiftAmt) & (localHistoryTableSize - 1);
-}
-
-inline
-void
-TournamentBP::updateGlobalHistTaken()
-{
- globalHistory = (globalHistory << 1) | 1;
- globalHistory = globalHistory & globalHistoryMask;
-}
-
-inline
-void
-TournamentBP::updateGlobalHistNotTaken()
-{
- globalHistory = (globalHistory << 1);
- globalHistory = globalHistory & globalHistoryMask;
-}
-
-inline
-void
-TournamentBP::updateLocalHistTaken(unsigned local_history_idx)
-{
- localHistoryTable[local_history_idx] =
- (localHistoryTable[local_history_idx] << 1) | 1;
-}
-
-inline
-void
-TournamentBP::updateLocalHistNotTaken(unsigned local_history_idx)
-{
- localHistoryTable[local_history_idx] =
- (localHistoryTable[local_history_idx] << 1);
-}
-
-bool
-TournamentBP::lookup(Addr &branch_addr, void * &bp_history)
-{
- bool local_prediction;
- unsigned local_history_idx;
- unsigned local_predictor_idx;
-
- bool global_prediction;
- bool choice_prediction;
-
- //Lookup in the local predictor to get its branch prediction
- local_history_idx = calcLocHistIdx(branch_addr);
- local_predictor_idx = localHistoryTable[local_history_idx]
- & localPredictorMask;
- local_prediction = localCtrs[local_predictor_idx].read() > threshold;
-
- //Lookup in the global predictor to get its branch prediction
- global_prediction = globalCtrs[globalHistory].read() > threshold;
-
- //Lookup in the choice predictor to see which one to use
- choice_prediction = choiceCtrs[globalHistory].read() > threshold;
-
- // Create BPHistory and pass it back to be recorded.
- BPHistory *history = new BPHistory;
- history->globalHistory = globalHistory;
- history->localPredTaken = local_prediction;
- history->globalPredTaken = global_prediction;
- history->globalUsed = choice_prediction;
- bp_history = (void *)history;
-
- assert(globalHistory < globalPredictorSize &&
- local_history_idx < localHistoryTableSize &&
- local_predictor_idx < localPredictorSize);
-
- // Commented code is for doing speculative update of counters and
- // all histories.
- if (choice_prediction) {
- if (global_prediction) {
-// updateHistoriesTaken(local_history_idx);
-// globalCtrs[globalHistory].increment();
-// localCtrs[local_history_idx].increment();
- updateGlobalHistTaken();
- return true;
- } else {
-// updateHistoriesNotTaken(local_history_idx);
-// globalCtrs[globalHistory].decrement();
-// localCtrs[local_history_idx].decrement();
- updateGlobalHistNotTaken();
- return false;
- }
- } else {
- if (local_prediction) {
-// updateHistoriesTaken(local_history_idx);
-// globalCtrs[globalHistory].increment();
-// localCtrs[local_history_idx].increment();
- updateGlobalHistTaken();
- return true;
- } else {
-// updateHistoriesNotTaken(local_history_idx);
-// globalCtrs[globalHistory].decrement();
-// localCtrs[local_history_idx].decrement();
- updateGlobalHistNotTaken();
- return false;
- }
- }
-}
-
-void
-TournamentBP::uncondBr(void * &bp_history)
-{
- // Create BPHistory and pass it back to be recorded.
- BPHistory *history = new BPHistory;
- history->globalHistory = globalHistory;
- history->localPredTaken = true;
- history->globalPredTaken = true;
- bp_history = static_cast<void *>(history);
-
- updateGlobalHistTaken();
-}
-
-void
-TournamentBP::update(Addr &branch_addr, bool taken, void *bp_history)
-{
- unsigned local_history_idx;
- unsigned local_predictor_idx;
- unsigned local_predictor_hist;
-
- // Get the local predictor's current prediction
- local_history_idx = calcLocHistIdx(branch_addr);
- local_predictor_hist = localHistoryTable[local_history_idx];
- local_predictor_idx = local_predictor_hist & localPredictorMask;
-
- // Update the choice predictor to tell it which one was correct if
- // there was a prediction.
- if (bp_history) {
- BPHistory *history = static_cast<BPHistory *>(bp_history);
- if (history->localPredTaken != history->globalPredTaken) {
- // If the local prediction matches the actual outcome,
- // decerement the counter. Otherwise increment the
- // counter.
- if (history->localPredTaken == taken) {
- choiceCtrs[globalHistory].decrement();
- } else if (history->globalPredTaken == taken){
- choiceCtrs[globalHistory].increment();
- }
- }
-
- // We're done with this history, now delete it.
- delete history;
- }
-
- assert(globalHistory < globalPredictorSize &&
- local_history_idx < localHistoryTableSize &&
- local_predictor_idx < localPredictorSize);
-
- // Update the counters and local history with the proper
- // resolution of the branch. Global history is updated
- // speculatively and restored upon squash() calls, so it does not
- // need to be updated.
- if (taken) {
- localCtrs[local_predictor_idx].increment();
- globalCtrs[globalHistory].increment();
-
- updateLocalHistTaken(local_history_idx);
- } else {
- localCtrs[local_predictor_idx].decrement();
- globalCtrs[globalHistory].decrement();
-
- updateLocalHistNotTaken(local_history_idx);
- }
-}
-
-void
-TournamentBP::squash(void *bp_history)
-{
- BPHistory *history = static_cast<BPHistory *>(bp_history);
-
- // Restore global history to state prior to this branch.
- globalHistory = history->globalHistory;
-
- // Delete this BPHistory now that we're done with it.
- delete history;
-}
-
-#ifdef DEBUG
-int
-TournamentBP::BPHistory::newCount = 0;
-#endif
projects / gem5.git / commitdiff