branch predictor: move out of o3 and inorder cpus

This patch moves the branch predictor files in the o3 and inorder directories
to src/cpu/pred. This allows sharing the branch predictor across different
cpu models.

This patch was originally posted by Timothy Jones in July 2010
but never made it to the repository.

--HG--
rename : src/cpu/o3/bpred_unit.cc => src/cpu/pred/bpred_unit.cc
rename : src/cpu/o3/bpred_unit.hh => src/cpu/pred/bpred_unit.hh
rename : src/cpu/o3/bpred_unit_impl.hh => src/cpu/pred/bpred_unit_impl.hh
rename : src/cpu/o3/sat_counter.hh => src/cpu/pred/sat_counter.hh

1 files changed, 0 insertions, 515 deletions

diff --git a/src/cpu/o3/bpred_unit_impl.hh b/src/cpu/o3/bpred_unit_impl.hh
deleted file mode 100644
index 43e801710..000000000
--- a/src/cpu/o3/bpred_unit_impl.hh
+++ /dev/null
@@ -1,515 +0,0 @@
-/*
- * Copyright (c) 2011-2012 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) 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 <algorithm>
-
-#include "arch/isa_traits.hh"
-#include "arch/types.hh"
-#include "arch/utility.hh"
-#include "base/trace.hh"
-#include "config/the_isa.hh"
-#include "cpu/o3/bpred_unit.hh"
-#include "debug/Fetch.hh"
-#include "params/DerivO3CPU.hh"
-
-template<class Impl>
-BPredUnit<Impl>::BPredUnit(DerivO3CPUParams *params)
-    : _name(params->name + ".BPredUnit"),
-      BTB(params->BTBEntries,
-          params->BTBTagSize,
-          params->instShiftAmt)
-{
-    // Setup the selected predictor.
-    if (params->predType == "local") {
-        localBP = new LocalBP(params->localPredictorSize,
-                              params->localCtrBits,
-                              params->instShiftAmt);
-        predictor = Local;
-    } else if (params->predType == "tournament") {
-        tournamentBP = new TournamentBP(params->localCtrBits,
-                                        params->localHistoryTableSize,
-                                        params->localHistoryBits,
-                                        params->globalPredictorSize,
-                                        params->globalHistoryBits,
-                                        params->globalCtrBits,
-                                        params->choicePredictorSize,
-                                        params->choiceCtrBits,
-                                        params->instShiftAmt);
-        predictor = Tournament;
-    } else {
-        fatal("Invalid BP selected!");
-    }
-
-    for (int i=0; i < Impl::MaxThreads; i++)
-        RAS[i].init(params->RASSize);
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::regStats()
-{
-    lookups
-        .name(name() + ".lookups")
-        .desc("Number of BP lookups")
-        ;
-
-    condPredicted
-        .name(name() + ".condPredicted")
-        .desc("Number of conditional branches predicted")
-        ;
-
-    condIncorrect
-        .name(name() + ".condIncorrect")
-        .desc("Number of conditional branches incorrect")
-        ;
-
-    BTBLookups
-        .name(name() + ".BTBLookups")
-        .desc("Number of BTB lookups")
-        ;
-
-    BTBHits
-        .name(name() + ".BTBHits")
-        .desc("Number of BTB hits")
-        ;
-
-    BTBCorrect
-        .name(name() + ".BTBCorrect")
-        .desc("Number of correct BTB predictions (this stat may not "
-              "work properly.")
-        ;
-
-    usedRAS
-        .name(name() + ".usedRAS")
-        .desc("Number of times the RAS was used to get a target.")
-        ;
-
-    RASIncorrect
-        .name(name() + ".RASInCorrect")
-        .desc("Number of incorrect RAS predictions.")
-        ;
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::drainSanityCheck() const
-{
-    // We shouldn't have any outstanding requests when we resume from
-    // a drained system.
-    for (int i = 0; i < Impl::MaxThreads; ++i)
-        assert(predHist[i].empty());
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::takeOverFrom()
-{
-    // Can reset all predictor state, but it's not necessarily better
-    // than leaving it be.
-/*
-    for (int i = 0; i < Impl::MaxThreads; ++i)
-        RAS[i].reset();
-
-    BP.reset();
-    BTB.reset();
-*/
-}
-
-template <class Impl>
-bool
-BPredUnit<Impl>::predict(DynInstPtr &inst, TheISA::PCState &pc, ThreadID tid)
-{
-    // See if branch predictor predicts taken.
-    // If so, get its target addr either from the BTB or the RAS.
-    // Save off record of branch stuff so the RAS can be fixed
-    // up once it's done.
-
-    bool pred_taken = false;
-    TheISA::PCState target = pc;
-
-    ++lookups;
-
-    void *bp_history = NULL;
-
-    if (inst->isUncondCtrl()) {
-        DPRINTF(Fetch, "BranchPred: [tid:%i]: Unconditional control.\n", tid);
-        pred_taken = true;
-        // Tell the BP there was an unconditional branch.
-        BPUncond(bp_history);
-    } else {
-        ++condPredicted;
-        pred_taken = BPLookup(pc.instAddr(), bp_history);
-
-        DPRINTF(Fetch, "BranchPred:[tid:%i]: [sn:%i] Branch predictor"
-                " predicted %i for PC %s\n",
-                tid, inst->seqNum,  pred_taken, inst->pcState());
-    }
-
-    DPRINTF(Fetch, "BranchPred: [tid:%i]: [sn:%i] Creating prediction history "
-                "for PC %s\n",
-            tid, inst->seqNum, inst->pcState());
-
-    PredictorHistory predict_record(inst->seqNum, pc.instAddr(),
-                                    pred_taken, bp_history, tid);
-
-    // Now lookup in the BTB or RAS.
-    if (pred_taken) {
-        if (inst->isReturn()) {
-            ++usedRAS;
-            predict_record.wasReturn = true;
-            // If it's a function return call, then look up the address
-            // in the RAS.
-            TheISA::PCState rasTop = RAS[tid].top();
-            target = TheISA::buildRetPC(pc, rasTop);
-
-            // Record the top entry of the RAS, and its index.
-            predict_record.usedRAS = true;
-            predict_record.RASIndex = RAS[tid].topIdx();
-            predict_record.RASTarget = rasTop;
-
-            RAS[tid].pop();
-
-            DPRINTF(Fetch, "BranchPred: [tid:%i]: Instruction %s is a return, "
-                    "RAS predicted target: %s, RAS index: %i.\n",
-                    tid, inst->pcState(), target, predict_record.RASIndex);
-        } else {
-            ++BTBLookups;
-
-            if (inst->isCall()) {
-                RAS[tid].push(pc);
-                predict_record.pushedRAS = true;
-                // Record that it was a call so that the top RAS entry can
-                // be popped off if the speculation is incorrect.
-                predict_record.wasCall = true;
-
-                DPRINTF(Fetch, "BranchPred: [tid:%i]: Instruction %s was a "
-                        "call, adding %s to the RAS index: %i.\n",
-                        tid, inst->pcState(), pc, RAS[tid].topIdx());
-            }
-
-            if (BTB.valid(pc.instAddr(), tid)) {
-                ++BTBHits;
-                predict_record.validBTB = true;
-
-                // If it's not a return, use the BTB to get the target addr.
-                target = BTB.lookup(pc.instAddr(), tid);
-
-                DPRINTF(Fetch, "BranchPred: [tid:%i]: Instruction %s predicted"
-                        " target is %s.\n", tid, inst->pcState(), target);
-
-            } else {
-                DPRINTF(Fetch, "BranchPred: [tid:%i]: BTB doesn't have a "
-                        "valid entry.\n",tid);
-                pred_taken = false;
-                // The Direction of the branch predictor is altered because the
-                // BTB did not have an entry
-                // The predictor needs to be updated accordingly
-                if (!inst->isCall() && !inst->isReturn()) {
-                      BPBTBUpdate(pc.instAddr(), bp_history);
-                      DPRINTF(Fetch, "BranchPred: [tid:%i]:[sn:%i] BPBTBUpdate"
-                              " called for %s\n",
-                              tid, inst->seqNum, inst->pcState());
-                } else if (inst->isCall() && !inst->isUncondCtrl()) {
-                      RAS[tid].pop();
-                      predict_record.pushedRAS = false;
-                }
-                TheISA::advancePC(target, inst->staticInst);
-            }
-
-        }
-    } else {
-        if (inst->isReturn()) {
-           predict_record.wasReturn = true;
-        }
-        TheISA::advancePC(target, inst->staticInst);
-    }
-
-    pc = target;
-
-    predHist[tid].push_front(predict_record);
-
-    DPRINTF(Fetch, "BranchPred: [tid:%i]: [sn:%i]: History entry added."
-            "predHist.size(): %i\n", tid, inst->seqNum, predHist[tid].size());
-
-    return pred_taken;
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::update(const InstSeqNum &done_sn, ThreadID tid)
-{
-    DPRINTF(Fetch, "BranchPred: [tid:%i]: Committing branches until "
-            "[sn:%lli].\n", tid, done_sn);
-
-    while (!predHist[tid].empty() &&
-           predHist[tid].back().seqNum <= done_sn) {
-        // Update the branch predictor with the correct results.
-        BPUpdate(predHist[tid].back().pc,
-                 predHist[tid].back().predTaken,
-                 predHist[tid].back().bpHistory, false);
-
-        predHist[tid].pop_back();
-    }
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::squash(const InstSeqNum &squashed_sn, ThreadID tid)
-{
-    History &pred_hist = predHist[tid];
-
-    while (!pred_hist.empty() &&
-           pred_hist.front().seqNum > squashed_sn) {
-        if (pred_hist.front().usedRAS) {
-            DPRINTF(Fetch, "BranchPred: [tid:%i]: Restoring top of RAS to: %i,"
-                    " target: %s.\n", tid,
-                    pred_hist.front().RASIndex, pred_hist.front().RASTarget);
-
-            RAS[tid].restore(pred_hist.front().RASIndex,
-                             pred_hist.front().RASTarget);
-        } else if(pred_hist.front().wasCall && pred_hist.front().pushedRAS) {
-                 // Was a call but predicated false. Pop RAS here
-                 DPRINTF(Fetch, "BranchPred: [tid: %i] Squashing"
-                         "  Call [sn:%i] PC: %s Popping RAS\n", tid,
-                         pred_hist.front().seqNum, pred_hist.front().pc);
-                 RAS[tid].pop();
-           }
-
-        // This call should delete the bpHistory.
-        BPSquash(pred_hist.front().bpHistory);
-
-        DPRINTF(Fetch, "BranchPred: [tid:%i]: Removing history for [sn:%i] "
-                "PC %s.\n", tid, pred_hist.front().seqNum,
-                pred_hist.front().pc);
-
-        pred_hist.pop_front();
-
-        DPRINTF(Fetch, "[tid:%i]: predHist.size(): %i\n",
-                tid, predHist[tid].size());
-    }
-
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::squash(const InstSeqNum &squashed_sn,
-                        const TheISA::PCState &corrTarget,
-                        bool actually_taken,
-                        ThreadID tid)
-{
-    // Now that we know that a branch was mispredicted, we need to undo
-    // all the branches that have been seen up until this branch and
-    // fix up everything.
-    // NOTE: This should be call conceivably in 2 scenarios:
-    // (1) After an branch is executed, it updates its status in the ROB
-    //     The commit stage then checks the ROB update and sends a signal to
-    //     the fetch stage to squash history after the mispredict
-    // (2) In the decode stage, you can find out early if a unconditional
-    //     PC-relative, branch was predicted incorrectly. If so, a signal
-    //     to the fetch stage is sent to squash history after the mispredict
-
-    History &pred_hist = predHist[tid];
-
-    ++condIncorrect;
-
-    DPRINTF(Fetch, "BranchPred: [tid:%i]: Squashing from sequence number %i, "
-            "setting target to %s.\n",
-            tid, squashed_sn, corrTarget);
-
-    // Squash All Branches AFTER this mispredicted branch
-    squash(squashed_sn, tid);
-
-    // If there's a squash due to a syscall, there may not be an entry
-    // corresponding to the squash.  In that case, don't bother trying to
-    // fix up the entry.
-    if (!pred_hist.empty()) {
-
-        HistoryIt hist_it = pred_hist.begin();
-        //HistoryIt hist_it = find(pred_hist.begin(), pred_hist.end(),
-        //                       squashed_sn);
-
-        //assert(hist_it != pred_hist.end());
-        if (pred_hist.front().seqNum != squashed_sn) {
-            DPRINTF(Fetch, "Front sn %i != Squash sn %i\n",
-                    pred_hist.front().seqNum, squashed_sn);
-
-            assert(pred_hist.front().seqNum == squashed_sn);
-        }
-
-
-        if ((*hist_it).usedRAS) {
-            ++RASIncorrect;
-        }
-
-        BPUpdate((*hist_it).pc, actually_taken,
-                 pred_hist.front().bpHistory, true);
-        if (actually_taken) {
-            if (hist_it->wasReturn && !hist_it->usedRAS) {
-                 DPRINTF(Fetch, "BranchPred: [tid: %i] Incorrectly predicted"
-                           "  return [sn:%i] PC: %s\n", tid, hist_it->seqNum,
-                            hist_it->pc);
-                 RAS[tid].pop();
-            }
-           DPRINTF(Fetch,"BranchPred: [tid: %i] BTB Update called for [sn:%i]"
-                            " PC: %s\n", tid,hist_it->seqNum, hist_it->pc);
-
-
-            BTB.update((*hist_it).pc, corrTarget, tid);
-
-        } else {
-           //Actually not Taken
-           if (hist_it->usedRAS) {
-                DPRINTF(Fetch,"BranchPred: [tid: %i] Incorrectly predicted"
-                           "  return [sn:%i] PC: %s Restoring RAS\n", tid,
-                           hist_it->seqNum, hist_it->pc);
-                DPRINTF(Fetch, "BranchPred: [tid:%i]: Restoring top of RAS"
-                               " to: %i, target: %s.\n", tid,
-                              hist_it->RASIndex, hist_it->RASTarget);
-                RAS[tid].restore(hist_it->RASIndex, hist_it->RASTarget);
-
-           } else if (hist_it->wasCall && hist_it->pushedRAS) {
-                 //Was a Call but predicated false. Pop RAS here
-                 DPRINTF(Fetch, "BranchPred: [tid: %i] Incorrectly predicted"
-                           "  Call [sn:%i] PC: %s Popping RAS\n", tid,
-                           hist_it->seqNum, hist_it->pc);
-                 RAS[tid].pop();
-           }
-        }
-        DPRINTF(Fetch, "BranchPred: [tid:%i]: Removing history for [sn:%i]"
-                       " PC %s  Actually Taken: %i\n", tid, hist_it->seqNum,
-                       hist_it->pc, actually_taken);
-
-        pred_hist.erase(hist_it);
-
-        DPRINTF(Fetch, "[tid:%i]: predHist.size(): %i\n", tid,
-                                         predHist[tid].size());
-    }
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::BPUncond(void * &bp_history)
-{
-    // Only the tournament predictor cares about unconditional branches.
-    if (predictor == Tournament) {
-        tournamentBP->uncondBr(bp_history);
-    }
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::BPSquash(void *bp_history)
-{
-    if (predictor == Local) {
-        localBP->squash(bp_history);
-    } else if (predictor == Tournament) {
-        tournamentBP->squash(bp_history);
-    } else {
-        panic("Predictor type is unexpected value!");
-    }
-}
-
-template <class Impl>
-bool
-BPredUnit<Impl>::BPLookup(Addr instPC, void * &bp_history)
-{
-    if (predictor == Local) {
-        return localBP->lookup(instPC, bp_history);
-    } else if (predictor == Tournament) {
-        return tournamentBP->lookup(instPC, bp_history);
-    } else {
-        panic("Predictor type is unexpected value!");
-    }
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::BPBTBUpdate(Addr instPC, void * &bp_history)
-{
-    if (predictor == Local) {
-        return localBP->BTBUpdate(instPC, bp_history);
-    } else if (predictor == Tournament) {
-        return tournamentBP->BTBUpdate(instPC, bp_history);
-    } else {
-        panic("Predictor type is unexpected value!");
-    }
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::BPUpdate(Addr instPC, bool taken, void *bp_history,
-                 bool squashed)
-{
-    if (predictor == Local) {
-        localBP->update(instPC, taken, bp_history);
-    } else if (predictor == Tournament) {
-        tournamentBP->update(instPC, taken, bp_history, squashed);
-    } else {
-        panic("Predictor type is unexpected value!");
-    }
-}
-
-template <class Impl>
-void
-BPredUnit<Impl>::dump()
-{
-    HistoryIt pred_hist_it;
-
-    for (int i = 0; i < Impl::MaxThreads; ++i) {
-        if (!predHist[i].empty()) {
-            pred_hist_it = predHist[i].begin();
-
-            cprintf("predHist[%i].size(): %i\n", i, predHist[i].size());
-
-            while (pred_hist_it != predHist[i].end()) {
-                cprintf("[sn:%lli], PC:%#x, tid:%i, predTaken:%i, "
-                        "bpHistory:%#x\n",
-                        pred_hist_it->seqNum, pred_hist_it->pc,
-                        pred_hist_it->tid, pred_hist_it->predTaken,
-                        pred_hist_it->bpHistory);
-                pred_hist_it++;
-            }
-
-            cprintf("\n");
-        }
-    }
-}