113626Sjairo.balart@metempsy.com/*
213626Sjairo.balart@metempsy.com * Copyright (c) 2014 The University of Wisconsin
313626Sjairo.balart@metempsy.com *
413626Sjairo.balart@metempsy.com * Copyright (c) 2006 INRIA (Institut National de Recherche en
513626Sjairo.balart@metempsy.com * Informatique et en Automatique  / French National Research Institute
613626Sjairo.balart@metempsy.com * for Computer Science and Applied Mathematics)
713626Sjairo.balart@metempsy.com *
813626Sjairo.balart@metempsy.com * All rights reserved.
913626Sjairo.balart@metempsy.com *
1013626Sjairo.balart@metempsy.com * Redistribution and use in source and binary forms, with or without
1113626Sjairo.balart@metempsy.com * modification, are permitted provided that the following conditions are
1213626Sjairo.balart@metempsy.com * met: redistributions of source code must retain the above copyright
1313626Sjairo.balart@metempsy.com * notice, this list of conditions and the following disclaimer;
1413626Sjairo.balart@metempsy.com * redistributions in binary form must reproduce the above copyright
1513626Sjairo.balart@metempsy.com * notice, this list of conditions and the following disclaimer in the
1613626Sjairo.balart@metempsy.com * documentation and/or other materials provided with the distribution;
1713626Sjairo.balart@metempsy.com * neither the name of the copyright holders nor the names of its
1813626Sjairo.balart@metempsy.com * contributors may be used to endorse or promote products derived from
1913626Sjairo.balart@metempsy.com * this software without specific prior written permission.
2013626Sjairo.balart@metempsy.com *
2113626Sjairo.balart@metempsy.com * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
2213626Sjairo.balart@metempsy.com * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
2313626Sjairo.balart@metempsy.com * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
2413626Sjairo.balart@metempsy.com * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
2513626Sjairo.balart@metempsy.com * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
2613626Sjairo.balart@metempsy.com * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
2713626Sjairo.balart@metempsy.com * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
2813626Sjairo.balart@metempsy.com * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
2913626Sjairo.balart@metempsy.com * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
3013626Sjairo.balart@metempsy.com * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
3113626Sjairo.balart@metempsy.com * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
3213626Sjairo.balart@metempsy.com *
3313626Sjairo.balart@metempsy.com * Authors: Vignyan Reddy, Dibakar Gope and Arthur Perais,
3413626Sjairo.balart@metempsy.com * from André Seznec's code.
3513626Sjairo.balart@metempsy.com */
3613626Sjairo.balart@metempsy.com
3713626Sjairo.balart@metempsy.com/* @file
3813626Sjairo.balart@metempsy.com * Implementation of a TAGE branch predictor
3913626Sjairo.balart@metempsy.com */
4013626Sjairo.balart@metempsy.com
4113626Sjairo.balart@metempsy.com#include "cpu/pred/tage_base.hh"
4213626Sjairo.balart@metempsy.com
4313626Sjairo.balart@metempsy.com#include "base/intmath.hh"
4413626Sjairo.balart@metempsy.com#include "base/logging.hh"
4513626Sjairo.balart@metempsy.com#include "debug/Fetch.hh"
4613626Sjairo.balart@metempsy.com#include "debug/Tage.hh"
4713626Sjairo.balart@metempsy.com
4813626Sjairo.balart@metempsy.comTAGEBase::TAGEBase(const TAGEBaseParams *p)
4913626Sjairo.balart@metempsy.com   : SimObject(p),
5013626Sjairo.balart@metempsy.com     logRatioBiModalHystEntries(p->logRatioBiModalHystEntries),
5113626Sjairo.balart@metempsy.com     nHistoryTables(p->nHistoryTables),
5213626Sjairo.balart@metempsy.com     tagTableCounterBits(p->tagTableCounterBits),
5313626Sjairo.balart@metempsy.com     tagTableUBits(p->tagTableUBits),
5413626Sjairo.balart@metempsy.com     histBufferSize(p->histBufferSize),
5513626Sjairo.balart@metempsy.com     minHist(p->minHist),
5613626Sjairo.balart@metempsy.com     maxHist(p->maxHist),
5713626Sjairo.balart@metempsy.com     pathHistBits(p->pathHistBits),
5813626Sjairo.balart@metempsy.com     tagTableTagWidths(p->tagTableTagWidths),
5913626Sjairo.balart@metempsy.com     logTagTableSizes(p->logTagTableSizes),
6013626Sjairo.balart@metempsy.com     threadHistory(p->numThreads),
6113626Sjairo.balart@metempsy.com     logUResetPeriod(p->logUResetPeriod),
6214081Sjavier.bueno@metempsy.com     initialTCounterValue(p->initialTCounterValue),
6313626Sjairo.balart@metempsy.com     numUseAltOnNa(p->numUseAltOnNa),
6413626Sjairo.balart@metempsy.com     useAltOnNaBits(p->useAltOnNaBits),
6513626Sjairo.balart@metempsy.com     maxNumAlloc(p->maxNumAlloc),
6613626Sjairo.balart@metempsy.com     noSkip(p->noSkip),
6713626Sjairo.balart@metempsy.com     speculativeHistUpdate(p->speculativeHistUpdate),
6814081Sjavier.bueno@metempsy.com     instShiftAmt(p->instShiftAmt),
6914081Sjavier.bueno@metempsy.com     initialized(false)
7013626Sjairo.balart@metempsy.com{
7113626Sjairo.balart@metempsy.com    if (noSkip.empty()) {
7213626Sjairo.balart@metempsy.com        // Set all the table to enabled by default
7313626Sjairo.balart@metempsy.com        noSkip.resize(nHistoryTables + 1, true);
7413626Sjairo.balart@metempsy.com    }
7513626Sjairo.balart@metempsy.com}
7613626Sjairo.balart@metempsy.com
7713626Sjairo.balart@metempsy.comTAGEBase::BranchInfo*
7813626Sjairo.balart@metempsy.comTAGEBase::makeBranchInfo() {
7913626Sjairo.balart@metempsy.com    return new BranchInfo(*this);
8013626Sjairo.balart@metempsy.com}
8113626Sjairo.balart@metempsy.com
8213626Sjairo.balart@metempsy.comvoid
8313626Sjairo.balart@metempsy.comTAGEBase::init()
8413626Sjairo.balart@metempsy.com{
8514081Sjavier.bueno@metempsy.com    if (initialized) {
8614081Sjavier.bueno@metempsy.com       return;
8714081Sjavier.bueno@metempsy.com    }
8813626Sjairo.balart@metempsy.com    // Current method for periodically resetting the u counter bits only
8913626Sjairo.balart@metempsy.com    // works for 1 or 2 bits
9013626Sjairo.balart@metempsy.com    // Also make sure that it is not 0
9113626Sjairo.balart@metempsy.com    assert(tagTableUBits <= 2 && (tagTableUBits > 0));
9213626Sjairo.balart@metempsy.com
9313626Sjairo.balart@metempsy.com    // we use int type for the path history, so it cannot be more than
9413626Sjairo.balart@metempsy.com    // its size
9513626Sjairo.balart@metempsy.com    assert(pathHistBits <= (sizeof(int)*8));
9613626Sjairo.balart@metempsy.com
9713626Sjairo.balart@metempsy.com    // initialize the counter to half of the period
9813626Sjairo.balart@metempsy.com    assert(logUResetPeriod != 0);
9914081Sjavier.bueno@metempsy.com    tCounter = initialTCounterValue;
10013626Sjairo.balart@metempsy.com
10113626Sjairo.balart@metempsy.com    assert(histBufferSize > maxHist * 2);
10213626Sjairo.balart@metempsy.com
10313626Sjairo.balart@metempsy.com    useAltPredForNewlyAllocated.resize(numUseAltOnNa, 0);
10413626Sjairo.balart@metempsy.com
10513626Sjairo.balart@metempsy.com    for (auto& history : threadHistory) {
10613626Sjairo.balart@metempsy.com        history.pathHist = 0;
10713626Sjairo.balart@metempsy.com        history.globalHistory = new uint8_t[histBufferSize];
10813626Sjairo.balart@metempsy.com        history.gHist = history.globalHistory;
10913626Sjairo.balart@metempsy.com        memset(history.gHist, 0, histBufferSize);
11013626Sjairo.balart@metempsy.com        history.ptGhist = 0;
11113626Sjairo.balart@metempsy.com    }
11213626Sjairo.balart@metempsy.com
11313626Sjairo.balart@metempsy.com    histLengths = new int [nHistoryTables+1];
11413626Sjairo.balart@metempsy.com
11513626Sjairo.balart@metempsy.com    calculateParameters();
11613626Sjairo.balart@metempsy.com
11713626Sjairo.balart@metempsy.com    assert(tagTableTagWidths.size() == (nHistoryTables+1));
11813626Sjairo.balart@metempsy.com    assert(logTagTableSizes.size() == (nHistoryTables+1));
11913626Sjairo.balart@metempsy.com
12013626Sjairo.balart@metempsy.com    // First entry is for the Bimodal table and it is untagged in this
12113626Sjairo.balart@metempsy.com    // implementation
12213626Sjairo.balart@metempsy.com    assert(tagTableTagWidths[0] == 0);
12313626Sjairo.balart@metempsy.com
12413626Sjairo.balart@metempsy.com    for (auto& history : threadHistory) {
12513626Sjairo.balart@metempsy.com        history.computeIndices = new FoldedHistory[nHistoryTables+1];
12613626Sjairo.balart@metempsy.com        history.computeTags[0] = new FoldedHistory[nHistoryTables+1];
12713626Sjairo.balart@metempsy.com        history.computeTags[1] = new FoldedHistory[nHistoryTables+1];
12813626Sjairo.balart@metempsy.com
12913626Sjairo.balart@metempsy.com        initFoldedHistories(history);
13013626Sjairo.balart@metempsy.com    }
13113626Sjairo.balart@metempsy.com
13213626Sjairo.balart@metempsy.com    const uint64_t bimodalTableSize = ULL(1) << logTagTableSizes[0];
13313626Sjairo.balart@metempsy.com    btablePrediction.resize(bimodalTableSize, false);
13413626Sjairo.balart@metempsy.com    btableHysteresis.resize(bimodalTableSize >> logRatioBiModalHystEntries,
13513626Sjairo.balart@metempsy.com                            true);
13613626Sjairo.balart@metempsy.com
13713626Sjairo.balart@metempsy.com    gtable = new TageEntry*[nHistoryTables + 1];
13813626Sjairo.balart@metempsy.com    buildTageTables();
13913626Sjairo.balart@metempsy.com
14013626Sjairo.balart@metempsy.com    tableIndices = new int [nHistoryTables+1];
14113626Sjairo.balart@metempsy.com    tableTags = new int [nHistoryTables+1];
14214081Sjavier.bueno@metempsy.com    initialized = true;
14313626Sjairo.balart@metempsy.com}
14413626Sjairo.balart@metempsy.com
14513626Sjairo.balart@metempsy.comvoid
14613626Sjairo.balart@metempsy.comTAGEBase::initFoldedHistories(ThreadHistory & history)
14713626Sjairo.balart@metempsy.com{
14813626Sjairo.balart@metempsy.com    for (int i = 1; i <= nHistoryTables; i++) {
14913626Sjairo.balart@metempsy.com        history.computeIndices[i].init(
15013626Sjairo.balart@metempsy.com            histLengths[i], (logTagTableSizes[i]));
15113626Sjairo.balart@metempsy.com        history.computeTags[0][i].init(
15213626Sjairo.balart@metempsy.com            history.computeIndices[i].origLength, tagTableTagWidths[i]);
15313626Sjairo.balart@metempsy.com        history.computeTags[1][i].init(
15413626Sjairo.balart@metempsy.com            history.computeIndices[i].origLength, tagTableTagWidths[i]-1);
15513626Sjairo.balart@metempsy.com        DPRINTF(Tage, "HistLength:%d, TTSize:%d, TTTWidth:%d\n",
15613626Sjairo.balart@metempsy.com                histLengths[i], logTagTableSizes[i], tagTableTagWidths[i]);
15713626Sjairo.balart@metempsy.com    }
15813626Sjairo.balart@metempsy.com}
15913626Sjairo.balart@metempsy.com
16013626Sjairo.balart@metempsy.comvoid
16113626Sjairo.balart@metempsy.comTAGEBase::buildTageTables()
16213626Sjairo.balart@metempsy.com{
16313626Sjairo.balart@metempsy.com    for (int i = 1; i <= nHistoryTables; i++) {
16413626Sjairo.balart@metempsy.com        gtable[i] = new TageEntry[1<<(logTagTableSizes[i])];
16513626Sjairo.balart@metempsy.com    }
16613626Sjairo.balart@metempsy.com}
16713626Sjairo.balart@metempsy.com
16813626Sjairo.balart@metempsy.comvoid
16913626Sjairo.balart@metempsy.comTAGEBase::calculateParameters()
17013626Sjairo.balart@metempsy.com{
17113626Sjairo.balart@metempsy.com    histLengths[1] = minHist;
17213626Sjairo.balart@metempsy.com    histLengths[nHistoryTables] = maxHist;
17313626Sjairo.balart@metempsy.com
17413626Sjairo.balart@metempsy.com    for (int i = 2; i <= nHistoryTables; i++) {
17513626Sjairo.balart@metempsy.com        histLengths[i] = (int) (((double) minHist *
17613626Sjairo.balart@metempsy.com                       pow ((double) (maxHist) / (double) minHist,
17713626Sjairo.balart@metempsy.com                           (double) (i - 1) / (double) ((nHistoryTables- 1))))
17813626Sjairo.balart@metempsy.com                       + 0.5);
17913626Sjairo.balart@metempsy.com    }
18013626Sjairo.balart@metempsy.com}
18113626Sjairo.balart@metempsy.com
18213626Sjairo.balart@metempsy.comvoid
18313626Sjairo.balart@metempsy.comTAGEBase::btbUpdate(ThreadID tid, Addr branch_pc, BranchInfo* &bi)
18413626Sjairo.balart@metempsy.com{
18513626Sjairo.balart@metempsy.com    if (speculativeHistUpdate) {
18613626Sjairo.balart@metempsy.com        ThreadHistory& tHist = threadHistory[tid];
18713626Sjairo.balart@metempsy.com        DPRINTF(Tage, "BTB miss resets prediction: %lx\n", branch_pc);
18813626Sjairo.balart@metempsy.com        assert(tHist.gHist == &tHist.globalHistory[tHist.ptGhist]);
18913626Sjairo.balart@metempsy.com        tHist.gHist[0] = 0;
19013626Sjairo.balart@metempsy.com        for (int i = 1; i <= nHistoryTables; i++) {
19113626Sjairo.balart@metempsy.com            tHist.computeIndices[i].comp = bi->ci[i];
19213626Sjairo.balart@metempsy.com            tHist.computeTags[0][i].comp = bi->ct0[i];
19313626Sjairo.balart@metempsy.com            tHist.computeTags[1][i].comp = bi->ct1[i];
19413626Sjairo.balart@metempsy.com            tHist.computeIndices[i].update(tHist.gHist);
19513626Sjairo.balart@metempsy.com            tHist.computeTags[0][i].update(tHist.gHist);
19613626Sjairo.balart@metempsy.com            tHist.computeTags[1][i].update(tHist.gHist);
19713626Sjairo.balart@metempsy.com        }
19813626Sjairo.balart@metempsy.com    }
19913626Sjairo.balart@metempsy.com}
20013626Sjairo.balart@metempsy.com
20113626Sjairo.balart@metempsy.comint
20213626Sjairo.balart@metempsy.comTAGEBase::bindex(Addr pc_in) const
20313626Sjairo.balart@metempsy.com{
20413626Sjairo.balart@metempsy.com    return ((pc_in >> instShiftAmt) & ((ULL(1) << (logTagTableSizes[0])) - 1));
20513626Sjairo.balart@metempsy.com}
20613626Sjairo.balart@metempsy.com
20713626Sjairo.balart@metempsy.comint
20813626Sjairo.balart@metempsy.comTAGEBase::F(int A, int size, int bank) const
20913626Sjairo.balart@metempsy.com{
21013626Sjairo.balart@metempsy.com    int A1, A2;
21113626Sjairo.balart@metempsy.com
21213626Sjairo.balart@metempsy.com    A = A & ((ULL(1) << size) - 1);
21313626Sjairo.balart@metempsy.com    A1 = (A & ((ULL(1) << logTagTableSizes[bank]) - 1));
21413626Sjairo.balart@metempsy.com    A2 = (A >> logTagTableSizes[bank]);
21513626Sjairo.balart@metempsy.com    A2 = ((A2 << bank) & ((ULL(1) << logTagTableSizes[bank]) - 1))
21613626Sjairo.balart@metempsy.com       + (A2 >> (logTagTableSizes[bank] - bank));
21713626Sjairo.balart@metempsy.com    A = A1 ^ A2;
21813626Sjairo.balart@metempsy.com    A = ((A << bank) & ((ULL(1) << logTagTableSizes[bank]) - 1))
21913626Sjairo.balart@metempsy.com      + (A >> (logTagTableSizes[bank] - bank));
22013626Sjairo.balart@metempsy.com    return (A);
22113626Sjairo.balart@metempsy.com}
22213626Sjairo.balart@metempsy.com
22313626Sjairo.balart@metempsy.com// gindex computes a full hash of pc, ghist and pathHist
22413626Sjairo.balart@metempsy.comint
22513626Sjairo.balart@metempsy.comTAGEBase::gindex(ThreadID tid, Addr pc, int bank) const
22613626Sjairo.balart@metempsy.com{
22713626Sjairo.balart@metempsy.com    int index;
22813626Sjairo.balart@metempsy.com    int hlen = (histLengths[bank] > pathHistBits) ? pathHistBits :
22913626Sjairo.balart@metempsy.com                                                    histLengths[bank];
23013626Sjairo.balart@metempsy.com    const unsigned int shiftedPc = pc >> instShiftAmt;
23113626Sjairo.balart@metempsy.com    index =
23213626Sjairo.balart@metempsy.com        shiftedPc ^
23313626Sjairo.balart@metempsy.com        (shiftedPc >> ((int) abs(logTagTableSizes[bank] - bank) + 1)) ^
23413626Sjairo.balart@metempsy.com        threadHistory[tid].computeIndices[bank].comp ^
23513626Sjairo.balart@metempsy.com        F(threadHistory[tid].pathHist, hlen, bank);
23613626Sjairo.balart@metempsy.com
23713626Sjairo.balart@metempsy.com    return (index & ((ULL(1) << (logTagTableSizes[bank])) - 1));
23813626Sjairo.balart@metempsy.com}
23913626Sjairo.balart@metempsy.com
24013626Sjairo.balart@metempsy.com
24113626Sjairo.balart@metempsy.com// Tag computation
24213626Sjairo.balart@metempsy.comuint16_t
24313626Sjairo.balart@metempsy.comTAGEBase::gtag(ThreadID tid, Addr pc, int bank) const
24413626Sjairo.balart@metempsy.com{
24513626Sjairo.balart@metempsy.com    int tag = (pc >> instShiftAmt) ^
24613626Sjairo.balart@metempsy.com              threadHistory[tid].computeTags[0][bank].comp ^
24713626Sjairo.balart@metempsy.com              (threadHistory[tid].computeTags[1][bank].comp << 1);
24813626Sjairo.balart@metempsy.com
24913626Sjairo.balart@metempsy.com    return (tag & ((ULL(1) << tagTableTagWidths[bank]) - 1));
25013626Sjairo.balart@metempsy.com}
25113626Sjairo.balart@metempsy.com
25213626Sjairo.balart@metempsy.com
25313626Sjairo.balart@metempsy.com// Up-down saturating counter
25413626Sjairo.balart@metempsy.comtemplate<typename T>
25513626Sjairo.balart@metempsy.comvoid
25613626Sjairo.balart@metempsy.comTAGEBase::ctrUpdate(T & ctr, bool taken, int nbits)
25713626Sjairo.balart@metempsy.com{
25813626Sjairo.balart@metempsy.com    assert(nbits <= sizeof(T) << 3);
25913626Sjairo.balart@metempsy.com    if (taken) {
26013626Sjairo.balart@metempsy.com        if (ctr < ((1 << (nbits - 1)) - 1))
26113626Sjairo.balart@metempsy.com            ctr++;
26213626Sjairo.balart@metempsy.com    } else {
26313626Sjairo.balart@metempsy.com        if (ctr > -(1 << (nbits - 1)))
26413626Sjairo.balart@metempsy.com            ctr--;
26513626Sjairo.balart@metempsy.com    }
26613626Sjairo.balart@metempsy.com}
26713626Sjairo.balart@metempsy.com
26813626Sjairo.balart@metempsy.com// int8_t and int versions of this function may be needed
26913626Sjairo.balart@metempsy.comtemplate void TAGEBase::ctrUpdate(int8_t & ctr, bool taken, int nbits);
27013626Sjairo.balart@metempsy.comtemplate void TAGEBase::ctrUpdate(int & ctr, bool taken, int nbits);
27113626Sjairo.balart@metempsy.com
27213626Sjairo.balart@metempsy.com// Up-down unsigned saturating counter
27313626Sjairo.balart@metempsy.comvoid
27413626Sjairo.balart@metempsy.comTAGEBase::unsignedCtrUpdate(uint8_t & ctr, bool up, unsigned nbits)
27513626Sjairo.balart@metempsy.com{
27613626Sjairo.balart@metempsy.com    assert(nbits <= sizeof(uint8_t) << 3);
27713626Sjairo.balart@metempsy.com    if (up) {
27813626Sjairo.balart@metempsy.com        if (ctr < ((1 << nbits) - 1))
27913626Sjairo.balart@metempsy.com            ctr++;
28013626Sjairo.balart@metempsy.com    } else {
28113626Sjairo.balart@metempsy.com        if (ctr)
28213626Sjairo.balart@metempsy.com            ctr--;
28313626Sjairo.balart@metempsy.com    }
28413626Sjairo.balart@metempsy.com}
28513626Sjairo.balart@metempsy.com
28613626Sjairo.balart@metempsy.com// Bimodal prediction
28713626Sjairo.balart@metempsy.combool
28813626Sjairo.balart@metempsy.comTAGEBase::getBimodePred(Addr pc, BranchInfo* bi) const
28913626Sjairo.balart@metempsy.com{
29013626Sjairo.balart@metempsy.com    return btablePrediction[bi->bimodalIndex];
29113626Sjairo.balart@metempsy.com}
29213626Sjairo.balart@metempsy.com
29313626Sjairo.balart@metempsy.com
29413626Sjairo.balart@metempsy.com// Update the bimodal predictor: a hysteresis bit is shared among N prediction
29513626Sjairo.balart@metempsy.com// bits (N = 2 ^ logRatioBiModalHystEntries)
29613626Sjairo.balart@metempsy.comvoid
29713626Sjairo.balart@metempsy.comTAGEBase::baseUpdate(Addr pc, bool taken, BranchInfo* bi)
29813626Sjairo.balart@metempsy.com{
29913626Sjairo.balart@metempsy.com    int inter = (btablePrediction[bi->bimodalIndex] << 1)
30013626Sjairo.balart@metempsy.com        + btableHysteresis[bi->bimodalIndex >> logRatioBiModalHystEntries];
30113626Sjairo.balart@metempsy.com    if (taken) {
30213626Sjairo.balart@metempsy.com        if (inter < 3)
30313626Sjairo.balart@metempsy.com            inter++;
30413626Sjairo.balart@metempsy.com    } else if (inter > 0) {
30513626Sjairo.balart@metempsy.com        inter--;
30613626Sjairo.balart@metempsy.com    }
30713626Sjairo.balart@metempsy.com    const bool pred = inter >> 1;
30813626Sjairo.balart@metempsy.com    const bool hyst = inter & 1;
30913626Sjairo.balart@metempsy.com    btablePrediction[bi->bimodalIndex] = pred;
31013626Sjairo.balart@metempsy.com    btableHysteresis[bi->bimodalIndex >> logRatioBiModalHystEntries] = hyst;
31113626Sjairo.balart@metempsy.com    DPRINTF(Tage, "Updating branch %lx, pred:%d, hyst:%d\n", pc, pred, hyst);
31213626Sjairo.balart@metempsy.com}
31313626Sjairo.balart@metempsy.com
31413626Sjairo.balart@metempsy.com// shifting the global history:  we manage the history in a big table in order
31513626Sjairo.balart@metempsy.com// to reduce simulation time
31613626Sjairo.balart@metempsy.comvoid
31713626Sjairo.balart@metempsy.comTAGEBase::updateGHist(uint8_t * &h, bool dir, uint8_t * tab, int &pt)
31813626Sjairo.balart@metempsy.com{
31913626Sjairo.balart@metempsy.com    if (pt == 0) {
32013626Sjairo.balart@metempsy.com        DPRINTF(Tage, "Rolling over the histories\n");
32113626Sjairo.balart@metempsy.com         // Copy beginning of globalHistoryBuffer to end, such that
32213626Sjairo.balart@metempsy.com         // the last maxHist outcomes are still reachable
32313626Sjairo.balart@metempsy.com         // through pt[0 .. maxHist - 1].
32413626Sjairo.balart@metempsy.com         for (int i = 0; i < maxHist; i++)
32513626Sjairo.balart@metempsy.com             tab[histBufferSize - maxHist + i] = tab[i];
32613626Sjairo.balart@metempsy.com         pt =  histBufferSize - maxHist;
32713626Sjairo.balart@metempsy.com         h = &tab[pt];
32813626Sjairo.balart@metempsy.com    }
32913626Sjairo.balart@metempsy.com    pt--;
33013626Sjairo.balart@metempsy.com    h--;
33113626Sjairo.balart@metempsy.com    h[0] = (dir) ? 1 : 0;
33213626Sjairo.balart@metempsy.com}
33313626Sjairo.balart@metempsy.com
33413626Sjairo.balart@metempsy.comvoid
33513626Sjairo.balart@metempsy.comTAGEBase::calculateIndicesAndTags(ThreadID tid, Addr branch_pc,
33613626Sjairo.balart@metempsy.com                                  BranchInfo* bi)
33713626Sjairo.balart@metempsy.com{
33813626Sjairo.balart@metempsy.com    // computes the table addresses and the partial tags
33913626Sjairo.balart@metempsy.com    for (int i = 1; i <= nHistoryTables; i++) {
34013626Sjairo.balart@metempsy.com        tableIndices[i] = gindex(tid, branch_pc, i);
34113626Sjairo.balart@metempsy.com        bi->tableIndices[i] = tableIndices[i];
34213626Sjairo.balart@metempsy.com        tableTags[i] = gtag(tid, branch_pc, i);
34313626Sjairo.balart@metempsy.com        bi->tableTags[i] = tableTags[i];
34413626Sjairo.balart@metempsy.com    }
34513626Sjairo.balart@metempsy.com}
34613626Sjairo.balart@metempsy.com
34713626Sjairo.balart@metempsy.comunsigned
34814081Sjavier.bueno@metempsy.comTAGEBase::getUseAltIdx(BranchInfo* bi, Addr branch_pc)
34913626Sjairo.balart@metempsy.com{
35013626Sjairo.balart@metempsy.com    // There is only 1 counter on the base TAGE implementation
35113626Sjairo.balart@metempsy.com    return 0;
35213626Sjairo.balart@metempsy.com}
35313626Sjairo.balart@metempsy.com
35413626Sjairo.balart@metempsy.combool
35513626Sjairo.balart@metempsy.comTAGEBase::tagePredict(ThreadID tid, Addr branch_pc,
35613626Sjairo.balart@metempsy.com              bool cond_branch, BranchInfo* bi)
35713626Sjairo.balart@metempsy.com{
35813626Sjairo.balart@metempsy.com    Addr pc = branch_pc;
35913626Sjairo.balart@metempsy.com    bool pred_taken = true;
36013626Sjairo.balart@metempsy.com
36113626Sjairo.balart@metempsy.com    if (cond_branch) {
36213626Sjairo.balart@metempsy.com        // TAGE prediction
36313626Sjairo.balart@metempsy.com
36413626Sjairo.balart@metempsy.com        calculateIndicesAndTags(tid, pc, bi);
36513626Sjairo.balart@metempsy.com
36613626Sjairo.balart@metempsy.com        bi->bimodalIndex = bindex(pc);
36713626Sjairo.balart@metempsy.com
36813626Sjairo.balart@metempsy.com        bi->hitBank = 0;
36913626Sjairo.balart@metempsy.com        bi->altBank = 0;
37013626Sjairo.balart@metempsy.com        //Look for the bank with longest matching history
37113626Sjairo.balart@metempsy.com        for (int i = nHistoryTables; i > 0; i--) {
37213626Sjairo.balart@metempsy.com            if (noSkip[i] &&
37313626Sjairo.balart@metempsy.com                gtable[i][tableIndices[i]].tag == tableTags[i]) {
37413626Sjairo.balart@metempsy.com                bi->hitBank = i;
37513626Sjairo.balart@metempsy.com                bi->hitBankIndex = tableIndices[bi->hitBank];
37613626Sjairo.balart@metempsy.com                break;
37713626Sjairo.balart@metempsy.com            }
37813626Sjairo.balart@metempsy.com        }
37913626Sjairo.balart@metempsy.com        //Look for the alternate bank
38013626Sjairo.balart@metempsy.com        for (int i = bi->hitBank - 1; i > 0; i--) {
38113626Sjairo.balart@metempsy.com            if (noSkip[i] &&
38213626Sjairo.balart@metempsy.com                gtable[i][tableIndices[i]].tag == tableTags[i]) {
38313626Sjairo.balart@metempsy.com                bi->altBank = i;
38413626Sjairo.balart@metempsy.com                bi->altBankIndex = tableIndices[bi->altBank];
38513626Sjairo.balart@metempsy.com                break;
38613626Sjairo.balart@metempsy.com            }
38713626Sjairo.balart@metempsy.com        }
38813626Sjairo.balart@metempsy.com        //computes the prediction and the alternate prediction
38913626Sjairo.balart@metempsy.com        if (bi->hitBank > 0) {
39013626Sjairo.balart@metempsy.com            if (bi->altBank > 0) {
39113626Sjairo.balart@metempsy.com                bi->altTaken =
39213626Sjairo.balart@metempsy.com                    gtable[bi->altBank][tableIndices[bi->altBank]].ctr >= 0;
39313626Sjairo.balart@metempsy.com                extraAltCalc(bi);
39413626Sjairo.balart@metempsy.com            }else {
39513626Sjairo.balart@metempsy.com                bi->altTaken = getBimodePred(pc, bi);
39613626Sjairo.balart@metempsy.com            }
39713626Sjairo.balart@metempsy.com
39813626Sjairo.balart@metempsy.com            bi->longestMatchPred =
39913626Sjairo.balart@metempsy.com                gtable[bi->hitBank][tableIndices[bi->hitBank]].ctr >= 0;
40013626Sjairo.balart@metempsy.com            bi->pseudoNewAlloc =
40113626Sjairo.balart@metempsy.com                abs(2 * gtable[bi->hitBank][bi->hitBankIndex].ctr + 1) <= 1;
40213626Sjairo.balart@metempsy.com
40313626Sjairo.balart@metempsy.com            //if the entry is recognized as a newly allocated entry and
40413626Sjairo.balart@metempsy.com            //useAltPredForNewlyAllocated is positive use the alternate
40513626Sjairo.balart@metempsy.com            //prediction
40614081Sjavier.bueno@metempsy.com            if ((useAltPredForNewlyAllocated[getUseAltIdx(bi, branch_pc)] < 0)
40714081Sjavier.bueno@metempsy.com                || ! bi->pseudoNewAlloc) {
40813626Sjairo.balart@metempsy.com                bi->tagePred = bi->longestMatchPred;
40913626Sjairo.balart@metempsy.com                bi->provider = TAGE_LONGEST_MATCH;
41013626Sjairo.balart@metempsy.com            } else {
41113626Sjairo.balart@metempsy.com                bi->tagePred = bi->altTaken;
41213626Sjairo.balart@metempsy.com                bi->provider = bi->altBank ? TAGE_ALT_MATCH
41313626Sjairo.balart@metempsy.com                                           : BIMODAL_ALT_MATCH;
41413626Sjairo.balart@metempsy.com            }
41513626Sjairo.balart@metempsy.com        } else {
41613626Sjairo.balart@metempsy.com            bi->altTaken = getBimodePred(pc, bi);
41713626Sjairo.balart@metempsy.com            bi->tagePred = bi->altTaken;
41813626Sjairo.balart@metempsy.com            bi->longestMatchPred = bi->altTaken;
41913626Sjairo.balart@metempsy.com            bi->provider = BIMODAL_ONLY;
42013626Sjairo.balart@metempsy.com        }
42113626Sjairo.balart@metempsy.com        //end TAGE prediction
42213626Sjairo.balart@metempsy.com
42313626Sjairo.balart@metempsy.com        pred_taken = (bi->tagePred);
42413626Sjairo.balart@metempsy.com        DPRINTF(Tage, "Predict for %lx: taken?:%d, tagePred:%d, altPred:%d\n",
42513626Sjairo.balart@metempsy.com                branch_pc, pred_taken, bi->tagePred, bi->altTaken);
42613626Sjairo.balart@metempsy.com    }
42713626Sjairo.balart@metempsy.com    bi->branchPC = branch_pc;
42813626Sjairo.balart@metempsy.com    bi->condBranch = cond_branch;
42913626Sjairo.balart@metempsy.com    return pred_taken;
43013626Sjairo.balart@metempsy.com}
43113626Sjairo.balart@metempsy.com
43213626Sjairo.balart@metempsy.comvoid
43313685Sjavier.bueno@metempsy.comTAGEBase::adjustAlloc(bool & alloc, bool taken, bool pred_taken)
43413626Sjairo.balart@metempsy.com{
43513626Sjairo.balart@metempsy.com    // Nothing for this base class implementation
43613626Sjairo.balart@metempsy.com}
43713626Sjairo.balart@metempsy.com
43813626Sjairo.balart@metempsy.comvoid
43913626Sjairo.balart@metempsy.comTAGEBase::handleAllocAndUReset(bool alloc, bool taken, BranchInfo* bi,
44013626Sjairo.balart@metempsy.com                           int nrand)
44113626Sjairo.balart@metempsy.com{
44213626Sjairo.balart@metempsy.com    if (alloc) {
44313626Sjairo.balart@metempsy.com        // is there some "unuseful" entry to allocate
44413626Sjairo.balart@metempsy.com        uint8_t min = 1;
44513626Sjairo.balart@metempsy.com        for (int i = nHistoryTables; i > bi->hitBank; i--) {
44613626Sjairo.balart@metempsy.com            if (gtable[i][bi->tableIndices[i]].u < min) {
44713626Sjairo.balart@metempsy.com                min = gtable[i][bi->tableIndices[i]].u;
44813626Sjairo.balart@metempsy.com            }
44913626Sjairo.balart@metempsy.com        }
45013626Sjairo.balart@metempsy.com
45113626Sjairo.balart@metempsy.com        // we allocate an entry with a longer history
45213626Sjairo.balart@metempsy.com        // to  avoid ping-pong, we do not choose systematically the next
45313626Sjairo.balart@metempsy.com        // entry, but among the 3 next entries
45413626Sjairo.balart@metempsy.com        int Y = nrand &
45513626Sjairo.balart@metempsy.com            ((ULL(1) << (nHistoryTables - bi->hitBank - 1)) - 1);
45613626Sjairo.balart@metempsy.com        int X = bi->hitBank + 1;
45713626Sjairo.balart@metempsy.com        if (Y & 1) {
45813626Sjairo.balart@metempsy.com            X++;
45913626Sjairo.balart@metempsy.com            if (Y & 2)
46013626Sjairo.balart@metempsy.com                X++;
46113626Sjairo.balart@metempsy.com        }
46213626Sjairo.balart@metempsy.com        // No entry available, forces one to be available
46313626Sjairo.balart@metempsy.com        if (min > 0) {
46413626Sjairo.balart@metempsy.com            gtable[X][bi->tableIndices[X]].u = 0;
46513626Sjairo.balart@metempsy.com        }
46613626Sjairo.balart@metempsy.com
46713626Sjairo.balart@metempsy.com
46813626Sjairo.balart@metempsy.com        //Allocate entries
46913626Sjairo.balart@metempsy.com        unsigned numAllocated = 0;
47013626Sjairo.balart@metempsy.com        for (int i = X; i <= nHistoryTables; i++) {
47113626Sjairo.balart@metempsy.com            if ((gtable[i][bi->tableIndices[i]].u == 0)) {
47213626Sjairo.balart@metempsy.com                gtable[i][bi->tableIndices[i]].tag = bi->tableTags[i];
47313626Sjairo.balart@metempsy.com                gtable[i][bi->tableIndices[i]].ctr = (taken) ? 0 : -1;
47413626Sjairo.balart@metempsy.com                ++numAllocated;
47513626Sjairo.balart@metempsy.com                if (numAllocated == maxNumAlloc) {
47613626Sjairo.balart@metempsy.com                    break;
47713626Sjairo.balart@metempsy.com                }
47813626Sjairo.balart@metempsy.com            }
47913626Sjairo.balart@metempsy.com        }
48013626Sjairo.balart@metempsy.com    }
48113626Sjairo.balart@metempsy.com
48213626Sjairo.balart@metempsy.com    tCounter++;
48313626Sjairo.balart@metempsy.com
48413626Sjairo.balart@metempsy.com    handleUReset();
48513626Sjairo.balart@metempsy.com}
48613626Sjairo.balart@metempsy.com
48713626Sjairo.balart@metempsy.comvoid
48813626Sjairo.balart@metempsy.comTAGEBase::handleUReset()
48913626Sjairo.balart@metempsy.com{
49013626Sjairo.balart@metempsy.com    //periodic reset of u: reset is not complete but bit by bit
49113626Sjairo.balart@metempsy.com    if ((tCounter & ((ULL(1) << logUResetPeriod) - 1)) == 0) {
49213626Sjairo.balart@metempsy.com        // reset least significant bit
49313626Sjairo.balart@metempsy.com        // most significant bit becomes least significant bit
49413626Sjairo.balart@metempsy.com        for (int i = 1; i <= nHistoryTables; i++) {
49513626Sjairo.balart@metempsy.com            for (int j = 0; j < (ULL(1) << logTagTableSizes[i]); j++) {
49613626Sjairo.balart@metempsy.com                resetUctr(gtable[i][j].u);
49713626Sjairo.balart@metempsy.com            }
49813626Sjairo.balart@metempsy.com        }
49913626Sjairo.balart@metempsy.com    }
50013626Sjairo.balart@metempsy.com}
50113626Sjairo.balart@metempsy.com
50213626Sjairo.balart@metempsy.comvoid
50313626Sjairo.balart@metempsy.comTAGEBase::resetUctr(uint8_t & u)
50413626Sjairo.balart@metempsy.com{
50513626Sjairo.balart@metempsy.com    u >>= 1;
50613626Sjairo.balart@metempsy.com}
50713626Sjairo.balart@metempsy.com
50813626Sjairo.balart@metempsy.comvoid
50913626Sjairo.balart@metempsy.comTAGEBase::condBranchUpdate(ThreadID tid, Addr branch_pc, bool taken,
51014081Sjavier.bueno@metempsy.com    BranchInfo* bi, int nrand, Addr corrTarget, bool pred, bool preAdjustAlloc)
51113626Sjairo.balart@metempsy.com{
51213626Sjairo.balart@metempsy.com    // TAGE UPDATE
51313626Sjairo.balart@metempsy.com    // try to allocate a  new entries only if prediction was wrong
51413626Sjairo.balart@metempsy.com    bool alloc = (bi->tagePred != taken) && (bi->hitBank < nHistoryTables);
51514081Sjavier.bueno@metempsy.com
51614081Sjavier.bueno@metempsy.com    if (preAdjustAlloc) {
51714081Sjavier.bueno@metempsy.com        adjustAlloc(alloc, taken, pred);
51814081Sjavier.bueno@metempsy.com    }
51914081Sjavier.bueno@metempsy.com
52013626Sjairo.balart@metempsy.com    if (bi->hitBank > 0) {
52113626Sjairo.balart@metempsy.com        // Manage the selection between longest matching and alternate
52213626Sjairo.balart@metempsy.com        // matching for "pseudo"-newly allocated longest matching entry
52313626Sjairo.balart@metempsy.com        bool PseudoNewAlloc = bi->pseudoNewAlloc;
52413626Sjairo.balart@metempsy.com        // an entry is considered as newly allocated if its prediction
52513626Sjairo.balart@metempsy.com        // counter is weak
52613626Sjairo.balart@metempsy.com        if (PseudoNewAlloc) {
52713626Sjairo.balart@metempsy.com            if (bi->longestMatchPred == taken) {
52813626Sjairo.balart@metempsy.com                alloc = false;
52913626Sjairo.balart@metempsy.com            }
53013626Sjairo.balart@metempsy.com            // if it was delivering the correct prediction, no need to
53113626Sjairo.balart@metempsy.com            // allocate new entry even if the overall prediction was false
53213626Sjairo.balart@metempsy.com            if (bi->longestMatchPred != bi->altTaken) {
53314081Sjavier.bueno@metempsy.com                ctrUpdate(
53414081Sjavier.bueno@metempsy.com                    useAltPredForNewlyAllocated[getUseAltIdx(bi, branch_pc)],
53514081Sjavier.bueno@metempsy.com                    bi->altTaken == taken, useAltOnNaBits);
53613626Sjairo.balart@metempsy.com            }
53713626Sjairo.balart@metempsy.com        }
53813626Sjairo.balart@metempsy.com    }
53913626Sjairo.balart@metempsy.com
54014081Sjavier.bueno@metempsy.com    if (!preAdjustAlloc) {
54114081Sjavier.bueno@metempsy.com        adjustAlloc(alloc, taken, pred);
54214081Sjavier.bueno@metempsy.com    }
54313626Sjairo.balart@metempsy.com
54413626Sjairo.balart@metempsy.com    handleAllocAndUReset(alloc, taken, bi, nrand);
54513626Sjairo.balart@metempsy.com
54613626Sjairo.balart@metempsy.com    handleTAGEUpdate(branch_pc, taken, bi);
54713626Sjairo.balart@metempsy.com}
54813626Sjairo.balart@metempsy.com
54913626Sjairo.balart@metempsy.comvoid
55013626Sjairo.balart@metempsy.comTAGEBase::handleTAGEUpdate(Addr branch_pc, bool taken, BranchInfo* bi)
55113626Sjairo.balart@metempsy.com{
55213626Sjairo.balart@metempsy.com    if (bi->hitBank > 0) {
55313626Sjairo.balart@metempsy.com        DPRINTF(Tage, "Updating tag table entry (%d,%d) for branch %lx\n",
55413626Sjairo.balart@metempsy.com                bi->hitBank, bi->hitBankIndex, branch_pc);
55513626Sjairo.balart@metempsy.com        ctrUpdate(gtable[bi->hitBank][bi->hitBankIndex].ctr, taken,
55613626Sjairo.balart@metempsy.com                  tagTableCounterBits);
55713626Sjairo.balart@metempsy.com        // if the provider entry is not certified to be useful also update
55813626Sjairo.balart@metempsy.com        // the alternate prediction
55913626Sjairo.balart@metempsy.com        if (gtable[bi->hitBank][bi->hitBankIndex].u == 0) {
56013626Sjairo.balart@metempsy.com            if (bi->altBank > 0) {
56113626Sjairo.balart@metempsy.com                ctrUpdate(gtable[bi->altBank][bi->altBankIndex].ctr, taken,
56213626Sjairo.balart@metempsy.com                          tagTableCounterBits);
56313626Sjairo.balart@metempsy.com                DPRINTF(Tage, "Updating tag table entry (%d,%d) for"
56413626Sjairo.balart@metempsy.com                        " branch %lx\n", bi->hitBank, bi->hitBankIndex,
56513626Sjairo.balart@metempsy.com                        branch_pc);
56613626Sjairo.balart@metempsy.com            }
56713626Sjairo.balart@metempsy.com            if (bi->altBank == 0) {
56813626Sjairo.balart@metempsy.com                baseUpdate(branch_pc, taken, bi);
56913626Sjairo.balart@metempsy.com            }
57013626Sjairo.balart@metempsy.com        }
57113626Sjairo.balart@metempsy.com
57213626Sjairo.balart@metempsy.com        // update the u counter
57313626Sjairo.balart@metempsy.com        if (bi->tagePred != bi->altTaken) {
57413626Sjairo.balart@metempsy.com            unsignedCtrUpdate(gtable[bi->hitBank][bi->hitBankIndex].u,
57513626Sjairo.balart@metempsy.com                              bi->tagePred == taken, tagTableUBits);
57613626Sjairo.balart@metempsy.com        }
57713626Sjairo.balart@metempsy.com    } else {
57813626Sjairo.balart@metempsy.com        baseUpdate(branch_pc, taken, bi);
57913626Sjairo.balart@metempsy.com    }
58013626Sjairo.balart@metempsy.com}
58113626Sjairo.balart@metempsy.com
58213626Sjairo.balart@metempsy.comvoid
58313626Sjairo.balart@metempsy.comTAGEBase::updateHistories(ThreadID tid, Addr branch_pc, bool taken,
58413626Sjairo.balart@metempsy.com                          BranchInfo* bi, bool speculative,
58513626Sjairo.balart@metempsy.com                          const StaticInstPtr &inst, Addr target)
58613626Sjairo.balart@metempsy.com{
58713626Sjairo.balart@metempsy.com    if (speculative != speculativeHistUpdate) {
58813626Sjairo.balart@metempsy.com        return;
58913626Sjairo.balart@metempsy.com    }
59013626Sjairo.balart@metempsy.com    ThreadHistory& tHist = threadHistory[tid];
59113626Sjairo.balart@metempsy.com    //  UPDATE HISTORIES
59213626Sjairo.balart@metempsy.com    bool pathbit = ((branch_pc >> instShiftAmt) & 1);
59313626Sjairo.balart@metempsy.com    //on a squash, return pointers to this and recompute indices.
59413626Sjairo.balart@metempsy.com    //update user history
59513626Sjairo.balart@metempsy.com    updateGHist(tHist.gHist, taken, tHist.globalHistory, tHist.ptGhist);
59613626Sjairo.balart@metempsy.com    tHist.pathHist = (tHist.pathHist << 1) + pathbit;
59713626Sjairo.balart@metempsy.com    tHist.pathHist = (tHist.pathHist & ((ULL(1) << pathHistBits) - 1));
59813626Sjairo.balart@metempsy.com
59913626Sjairo.balart@metempsy.com    if (speculative) {
60013626Sjairo.balart@metempsy.com        bi->ptGhist = tHist.ptGhist;
60113626Sjairo.balart@metempsy.com        bi->pathHist = tHist.pathHist;
60213626Sjairo.balart@metempsy.com    }
60313626Sjairo.balart@metempsy.com
60413626Sjairo.balart@metempsy.com    //prepare next index and tag computations for user branchs
60513626Sjairo.balart@metempsy.com    for (int i = 1; i <= nHistoryTables; i++)
60613626Sjairo.balart@metempsy.com    {
60713626Sjairo.balart@metempsy.com        if (speculative) {
60813626Sjairo.balart@metempsy.com            bi->ci[i]  = tHist.computeIndices[i].comp;
60913626Sjairo.balart@metempsy.com            bi->ct0[i] = tHist.computeTags[0][i].comp;
61013626Sjairo.balart@metempsy.com            bi->ct1[i] = tHist.computeTags[1][i].comp;
61113626Sjairo.balart@metempsy.com        }
61213626Sjairo.balart@metempsy.com        tHist.computeIndices[i].update(tHist.gHist);
61313626Sjairo.balart@metempsy.com        tHist.computeTags[0][i].update(tHist.gHist);
61413626Sjairo.balart@metempsy.com        tHist.computeTags[1][i].update(tHist.gHist);
61513626Sjairo.balart@metempsy.com    }
61613626Sjairo.balart@metempsy.com    DPRINTF(Tage, "Updating global histories with branch:%lx; taken?:%d, "
61713626Sjairo.balart@metempsy.com            "path Hist: %x; pointer:%d\n", branch_pc, taken, tHist.pathHist,
61813626Sjairo.balart@metempsy.com            tHist.ptGhist);
61913626Sjairo.balart@metempsy.com    assert(threadHistory[tid].gHist ==
62013626Sjairo.balart@metempsy.com            &threadHistory[tid].globalHistory[threadHistory[tid].ptGhist]);
62113626Sjairo.balart@metempsy.com}
62213626Sjairo.balart@metempsy.com
62313626Sjairo.balart@metempsy.comvoid
62413626Sjairo.balart@metempsy.comTAGEBase::squash(ThreadID tid, bool taken, TAGEBase::BranchInfo *bi,
62513626Sjairo.balart@metempsy.com                 Addr target)
62613626Sjairo.balart@metempsy.com{
62713626Sjairo.balart@metempsy.com    if (!speculativeHistUpdate) {
62813626Sjairo.balart@metempsy.com        /* If there are no speculative updates, no actions are needed */
62913626Sjairo.balart@metempsy.com        return;
63013626Sjairo.balart@metempsy.com    }
63113626Sjairo.balart@metempsy.com
63213626Sjairo.balart@metempsy.com    ThreadHistory& tHist = threadHistory[tid];
63313626Sjairo.balart@metempsy.com    DPRINTF(Tage, "Restoring branch info: %lx; taken? %d; PathHistory:%x, "
63413626Sjairo.balart@metempsy.com            "pointer:%d\n", bi->branchPC,taken, bi->pathHist, bi->ptGhist);
63513626Sjairo.balart@metempsy.com    tHist.pathHist = bi->pathHist;
63613626Sjairo.balart@metempsy.com    tHist.ptGhist = bi->ptGhist;
63713626Sjairo.balart@metempsy.com    tHist.gHist = &(tHist.globalHistory[tHist.ptGhist]);
63813626Sjairo.balart@metempsy.com    tHist.gHist[0] = (taken ? 1 : 0);
63913626Sjairo.balart@metempsy.com    for (int i = 1; i <= nHistoryTables; i++) {
64013626Sjairo.balart@metempsy.com        tHist.computeIndices[i].comp = bi->ci[i];
64113626Sjairo.balart@metempsy.com        tHist.computeTags[0][i].comp = bi->ct0[i];
64213626Sjairo.balart@metempsy.com        tHist.computeTags[1][i].comp = bi->ct1[i];
64313626Sjairo.balart@metempsy.com        tHist.computeIndices[i].update(tHist.gHist);
64413626Sjairo.balart@metempsy.com        tHist.computeTags[0][i].update(tHist.gHist);
64513626Sjairo.balart@metempsy.com        tHist.computeTags[1][i].update(tHist.gHist);
64613626Sjairo.balart@metempsy.com    }
64713626Sjairo.balart@metempsy.com}
64813626Sjairo.balart@metempsy.com
64913626Sjairo.balart@metempsy.comvoid
65013626Sjairo.balart@metempsy.comTAGEBase::extraAltCalc(BranchInfo* bi)
65113626Sjairo.balart@metempsy.com{
65213626Sjairo.balart@metempsy.com    // do nothing. This is only used in some derived classes
65313626Sjairo.balart@metempsy.com    return;
65413626Sjairo.balart@metempsy.com}
65513626Sjairo.balart@metempsy.com
65613626Sjairo.balart@metempsy.comvoid
65713626Sjairo.balart@metempsy.comTAGEBase::updateStats(bool taken, BranchInfo* bi)
65813626Sjairo.balart@metempsy.com{
65913626Sjairo.balart@metempsy.com    if (taken == bi->tagePred) {
66013626Sjairo.balart@metempsy.com        // correct prediction
66113626Sjairo.balart@metempsy.com        switch (bi->provider) {
66213626Sjairo.balart@metempsy.com          case BIMODAL_ONLY: tageBimodalProviderCorrect++; break;
66313626Sjairo.balart@metempsy.com          case TAGE_LONGEST_MATCH: tageLongestMatchProviderCorrect++; break;
66413626Sjairo.balart@metempsy.com          case BIMODAL_ALT_MATCH: bimodalAltMatchProviderCorrect++; break;
66513626Sjairo.balart@metempsy.com          case TAGE_ALT_MATCH: tageAltMatchProviderCorrect++; break;
66613626Sjairo.balart@metempsy.com        }
66713626Sjairo.balart@metempsy.com    } else {
66813626Sjairo.balart@metempsy.com        // wrong prediction
66913626Sjairo.balart@metempsy.com        switch (bi->provider) {
67013626Sjairo.balart@metempsy.com          case BIMODAL_ONLY: tageBimodalProviderWrong++; break;
67113626Sjairo.balart@metempsy.com          case TAGE_LONGEST_MATCH:
67213626Sjairo.balart@metempsy.com            tageLongestMatchProviderWrong++;
67313626Sjairo.balart@metempsy.com            if (bi->altTaken == taken) {
67413626Sjairo.balart@metempsy.com                tageAltMatchProviderWouldHaveHit++;
67513626Sjairo.balart@metempsy.com            }
67613626Sjairo.balart@metempsy.com            break;
67713626Sjairo.balart@metempsy.com          case BIMODAL_ALT_MATCH:
67813626Sjairo.balart@metempsy.com            bimodalAltMatchProviderWrong++;
67913626Sjairo.balart@metempsy.com            break;
68013626Sjairo.balart@metempsy.com          case TAGE_ALT_MATCH:
68113626Sjairo.balart@metempsy.com            tageAltMatchProviderWrong++;
68213626Sjairo.balart@metempsy.com            break;
68313626Sjairo.balart@metempsy.com        }
68413626Sjairo.balart@metempsy.com
68513626Sjairo.balart@metempsy.com        switch (bi->provider) {
68613626Sjairo.balart@metempsy.com          case BIMODAL_ALT_MATCH:
68713626Sjairo.balart@metempsy.com          case TAGE_ALT_MATCH:
68813626Sjairo.balart@metempsy.com            if (bi->longestMatchPred == taken) {
68913626Sjairo.balart@metempsy.com                tageLongestMatchProviderWouldHaveHit++;
69013626Sjairo.balart@metempsy.com            }
69113626Sjairo.balart@metempsy.com        }
69213626Sjairo.balart@metempsy.com    }
69313626Sjairo.balart@metempsy.com
69413626Sjairo.balart@metempsy.com    switch (bi->provider) {
69513626Sjairo.balart@metempsy.com      case TAGE_LONGEST_MATCH:
69613626Sjairo.balart@metempsy.com      case TAGE_ALT_MATCH:
69713626Sjairo.balart@metempsy.com        tageLongestMatchProvider[bi->hitBank]++;
69813626Sjairo.balart@metempsy.com        tageAltMatchProvider[bi->altBank]++;
69913626Sjairo.balart@metempsy.com        break;
70013626Sjairo.balart@metempsy.com    }
70113626Sjairo.balart@metempsy.com}
70213626Sjairo.balart@metempsy.com
70313626Sjairo.balart@metempsy.comunsigned
70413626Sjairo.balart@metempsy.comTAGEBase::getGHR(ThreadID tid, BranchInfo *bi) const
70513626Sjairo.balart@metempsy.com{
70613626Sjairo.balart@metempsy.com    unsigned val = 0;
70713626Sjairo.balart@metempsy.com    for (unsigned i = 0; i < 32; i++) {
70813626Sjairo.balart@metempsy.com        // Make sure we don't go out of bounds
70913626Sjairo.balart@metempsy.com        int gh_offset = bi->ptGhist + i;
71013626Sjairo.balart@metempsy.com        assert(&(threadHistory[tid].globalHistory[gh_offset]) <
71113626Sjairo.balart@metempsy.com               threadHistory[tid].globalHistory + histBufferSize);
71213626Sjairo.balart@metempsy.com        val |= ((threadHistory[tid].globalHistory[gh_offset] & 0x1) << i);
71313626Sjairo.balart@metempsy.com    }
71413626Sjairo.balart@metempsy.com
71513626Sjairo.balart@metempsy.com    return val;
71613626Sjairo.balart@metempsy.com}
71713626Sjairo.balart@metempsy.com
71813626Sjairo.balart@metempsy.comvoid
71913626Sjairo.balart@metempsy.comTAGEBase::regStats()
72013626Sjairo.balart@metempsy.com{
72113626Sjairo.balart@metempsy.com    tageLongestMatchProviderCorrect
72213626Sjairo.balart@metempsy.com        .name(name() + ".tageLongestMatchProviderCorrect")
72313626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Longest Match is the provider and "
72413626Sjairo.balart@metempsy.com              "the prediction is correct");
72513626Sjairo.balart@metempsy.com
72613626Sjairo.balart@metempsy.com    tageAltMatchProviderCorrect
72713626Sjairo.balart@metempsy.com        .name(name() + ".tageAltMatchProviderCorrect")
72813626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Alt Match is the provider and "
72913626Sjairo.balart@metempsy.com              "the prediction is correct");
73013626Sjairo.balart@metempsy.com
73113626Sjairo.balart@metempsy.com    bimodalAltMatchProviderCorrect
73213626Sjairo.balart@metempsy.com        .name(name() + ".bimodalAltMatchProviderCorrect")
73313626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Alt Match is the bimodal and it is the "
73413626Sjairo.balart@metempsy.com              "provider and the prediction is correct");
73513626Sjairo.balart@metempsy.com
73613626Sjairo.balart@metempsy.com    tageBimodalProviderCorrect
73713626Sjairo.balart@metempsy.com        .name(name() + ".tageBimodalProviderCorrect")
73813626Sjairo.balart@metempsy.com        .desc("Number of times there are no hits on the TAGE tables "
73913626Sjairo.balart@metempsy.com              "and the bimodal prediction is correct");
74013626Sjairo.balart@metempsy.com
74113626Sjairo.balart@metempsy.com    tageLongestMatchProviderWrong
74213626Sjairo.balart@metempsy.com        .name(name() + ".tageLongestMatchProviderWrong")
74313626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Longest Match is the provider and "
74413626Sjairo.balart@metempsy.com              "the prediction is wrong");
74513626Sjairo.balart@metempsy.com
74613626Sjairo.balart@metempsy.com    tageAltMatchProviderWrong
74713626Sjairo.balart@metempsy.com        .name(name() + ".tageAltMatchProviderWrong")
74813626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Alt Match is the provider and "
74913626Sjairo.balart@metempsy.com              "the prediction is wrong");
75013626Sjairo.balart@metempsy.com
75113626Sjairo.balart@metempsy.com    bimodalAltMatchProviderWrong
75213626Sjairo.balart@metempsy.com        .name(name() + ".bimodalAltMatchProviderWrong")
75313626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Alt Match is the bimodal and it is the "
75413626Sjairo.balart@metempsy.com              "provider and the prediction is wrong");
75513626Sjairo.balart@metempsy.com
75613626Sjairo.balart@metempsy.com    tageBimodalProviderWrong
75713626Sjairo.balart@metempsy.com        .name(name() + ".tageBimodalProviderWrong")
75813626Sjairo.balart@metempsy.com        .desc("Number of times there are no hits on the TAGE tables "
75913626Sjairo.balart@metempsy.com              "and the bimodal prediction is wrong");
76013626Sjairo.balart@metempsy.com
76113626Sjairo.balart@metempsy.com    tageAltMatchProviderWouldHaveHit
76213626Sjairo.balart@metempsy.com        .name(name() + ".tageAltMatchProviderWouldHaveHit")
76313626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Longest Match is the provider, "
76413626Sjairo.balart@metempsy.com              "the prediction is wrong and Alt Match prediction was correct");
76513626Sjairo.balart@metempsy.com
76613626Sjairo.balart@metempsy.com    tageLongestMatchProviderWouldHaveHit
76713626Sjairo.balart@metempsy.com        .name(name() + ".tageLongestMatchProviderWouldHaveHit")
76813626Sjairo.balart@metempsy.com        .desc("Number of times TAGE Alt Match is the provider, the "
76913626Sjairo.balart@metempsy.com              "prediction is wrong and Longest Match prediction was correct");
77013626Sjairo.balart@metempsy.com
77113626Sjairo.balart@metempsy.com    tageLongestMatchProvider
77213626Sjairo.balart@metempsy.com        .init(nHistoryTables + 1)
77313626Sjairo.balart@metempsy.com        .name(name() + ".tageLongestMatchProvider")
77413626Sjairo.balart@metempsy.com        .desc("TAGE provider for longest match");
77513626Sjairo.balart@metempsy.com
77613626Sjairo.balart@metempsy.com    tageAltMatchProvider
77713626Sjairo.balart@metempsy.com        .init(nHistoryTables + 1)
77813626Sjairo.balart@metempsy.com        .name(name() + ".tageAltMatchProvider")
77913626Sjairo.balart@metempsy.com        .desc("TAGE provider for alt match");
78013626Sjairo.balart@metempsy.com}
78113626Sjairo.balart@metempsy.com
78213626Sjairo.balart@metempsy.comint8_t
78313626Sjairo.balart@metempsy.comTAGEBase::getCtr(int hitBank, int hitBankIndex) const
78413626Sjairo.balart@metempsy.com{
78513626Sjairo.balart@metempsy.com    return gtable[hitBank][hitBankIndex].ctr;
78613626Sjairo.balart@metempsy.com}
78713626Sjairo.balart@metempsy.com
78813626Sjairo.balart@metempsy.comunsigned
78913626Sjairo.balart@metempsy.comTAGEBase::getTageCtrBits() const
79013626Sjairo.balart@metempsy.com{
79113626Sjairo.balart@metempsy.com    return tagTableCounterBits;
79213626Sjairo.balart@metempsy.com}
79313626Sjairo.balart@metempsy.com
79413626Sjairo.balart@metempsy.comint
79513626Sjairo.balart@metempsy.comTAGEBase::getPathHist(ThreadID tid) const
79613626Sjairo.balart@metempsy.com{
79713626Sjairo.balart@metempsy.com    return threadHistory[tid].pathHist;
79813626Sjairo.balart@metempsy.com}
79913626Sjairo.balart@metempsy.com
80013626Sjairo.balart@metempsy.combool
80113626Sjairo.balart@metempsy.comTAGEBase::isSpeculativeUpdateEnabled() const
80213626Sjairo.balart@metempsy.com{
80313626Sjairo.balart@metempsy.com    return speculativeHistUpdate;
80413626Sjairo.balart@metempsy.com}
80513626Sjairo.balart@metempsy.com
80614081Sjavier.bueno@metempsy.comsize_t
80714081Sjavier.bueno@metempsy.comTAGEBase::getSizeInBits() const {
80814081Sjavier.bueno@metempsy.com    size_t bits = 0;
80914081Sjavier.bueno@metempsy.com    for (int i = 1; i <= nHistoryTables; i++) {
81014081Sjavier.bueno@metempsy.com        bits += (1 << logTagTableSizes[i]) *
81114081Sjavier.bueno@metempsy.com            (tagTableCounterBits + tagTableUBits + tagTableTagWidths[i]);
81214081Sjavier.bueno@metempsy.com    }
81314081Sjavier.bueno@metempsy.com    uint64_t bimodalTableSize = ULL(1) << logTagTableSizes[0];
81414081Sjavier.bueno@metempsy.com    bits += numUseAltOnNa * useAltOnNaBits;
81514081Sjavier.bueno@metempsy.com    bits += bimodalTableSize;
81614081Sjavier.bueno@metempsy.com    bits += (bimodalTableSize >> logRatioBiModalHystEntries);
81714081Sjavier.bueno@metempsy.com    bits += histLengths[nHistoryTables];
81814081Sjavier.bueno@metempsy.com    bits += pathHistBits;
81914081Sjavier.bueno@metempsy.com    bits += logUResetPeriod;
82014081Sjavier.bueno@metempsy.com    return bits;
82114081Sjavier.bueno@metempsy.com}
82214081Sjavier.bueno@metempsy.com
82313626Sjairo.balart@metempsy.comTAGEBase*
82413626Sjairo.balart@metempsy.comTAGEBaseParams::create()
82513626Sjairo.balart@metempsy.com{
82613626Sjairo.balart@metempsy.com    return new TAGEBase(this);
82713626Sjairo.balart@metempsy.com}
828