cpu/pred/tage_base.cc

183 TAGEBase::btbUpdate(ThreadID tid, Addr branch_pc, BranchInfo* &bi)
191             tHist.computeIndices[i].comp = bi->ci[i];
192             tHist.computeTags[0][i].comp = bi->ct0[i];
193             tHist.computeTags[1][i].comp = bi->ct1[i];
288 TAGEBase::getBimodePred(Addr pc, BranchInfo* bi) const
290     return btablePrediction[bi->bimodalIndex];
297 TAGEBase::baseUpdate(Addr pc, bool taken, BranchInfo* bi)
299     int inter = (btablePrediction[bi->bimodalIndex] << 1)
300         + btableHysteresis[bi->bimodalIndex >> logRatioBiModalHystEntries];
309     btablePrediction[bi->bimodalIndex] = pred;
310     btableHysteresis[bi->bimodalIndex >> logRatioBiModalHystEntries] = hyst;
336                                   BranchInfo* bi)
341         bi->tableIndices[i] = tableIndices[i];
343         bi->tableTags[i] = tableTags[i];
348 TAGEBase::getUseAltIdx(BranchInfo* bi, Addr branch_pc)
356               bool cond_branch, BranchInfo* bi)
364         calculateIndicesAndTags(tid, pc, bi);
366         bi->bimodalIndex = bindex(pc);
368         bi->hitBank = 0;
369         bi->altBank = 0;
374                 bi->hitBank = i;
375                 bi->hitBankIndex = tableIndices[bi->hitBank];
380         for (int i = bi->hitBank - 1; i > 0; i--) {
383                 bi->altBank = i;
384                 bi->altBankIndex = tableIndices[bi->altBank];
389         if (bi->hitBank > 0) {
390             if (bi->altBank > 0) {
391                 bi->altTaken =
392                     gtable[bi->altBank][tableIndices[bi->altBank]].ctr >= 0;
393                 extraAltCalc(bi);
395                 bi->altTaken = getBimodePred(pc, bi);
398             bi->longestMatchPred =
399                 gtable[bi->hitBank][tableIndices[bi->hitBank]].ctr >= 0;
400             bi->pseudoNewAlloc =
401                 abs(2 * gtable[bi->hitBank][bi->hitBankIndex].ctr + 1) <= 1;
406             if ((useAltPredForNewlyAllocated[getUseAltIdx(bi, branch_pc)] < 0)
407                 || ! bi->pseudoNewAlloc) {
408                 bi->tagePred = bi->longestMatchPred;
409                 bi->provider = TAGE_LONGEST_MATCH;
411                 bi->tagePred = bi->altTaken;
412                 bi->provider = bi->altBank ? TAGE_ALT_MATCH
416             bi->altTaken = getBimodePred(pc, bi);
417             bi->tagePred = bi->altTaken;
418             bi->longestMatchPred = bi->altTaken;
419             bi->provider = BIMODAL_ONLY;
423         pred_taken = (bi->tagePred);
425                 branch_pc, pred_taken, bi->tagePred, bi->altTaken);
427     bi->branchPC = branch_pc;
428     bi->condBranch = cond_branch;
439 TAGEBase::handleAllocAndUReset(bool alloc, bool taken, BranchInfo* bi,
445         for (int i = nHistoryTables; i > bi->hitBank; i--) {
446             if (gtable[i][bi->tableIndices[i]].u < min) {
447                 min = gtable[i][bi->tableIndices[i]].u;
455             ((ULL(1) << (nHistoryTables - bi->hitBank - 1)) - 1);
456         int X = bi->hitBank + 1;
464             gtable[X][bi->tableIndices[X]].u = 0;
471             if ((gtable[i][bi->tableIndices[i]].u == 0)) {
472                 gtable[i][bi->tableIndices[i]].tag = bi->tableTags[i];
473                 gtable[i][bi->tableIndices[i]].ctr = (taken) ? 0 : -1;
510     BranchInfo* bi, int nrand, Addr corrTarget, bool pred, bool preAdjustAlloc)
514     bool alloc = (bi->tagePred != taken) && (bi->hitBank < nHistoryTables);
520     if (bi->hitBank > 0) {
523         bool PseudoNewAlloc = bi->pseudoNewAlloc;
527             if (bi->longestMatchPred == taken) {
532             if (bi->longestMatchPred != bi->altTaken) {
534                     useAltPredForNewlyAllocated[getUseAltIdx(bi, branch_pc)],
535                     bi->altTaken == taken, useAltOnNaBits);
544     handleAllocAndUReset(alloc, taken, bi, nrand);
546     handleTAGEUpdate(branch_pc, taken, bi);
550 TAGEBase::handleTAGEUpdate(Addr branch_pc, bool taken, BranchInfo* bi)
552     if (bi->hitBank > 0) {
554                 bi->hitBank, bi->hitBankIndex, branch_pc);
555         ctrUpdate(gtable[bi->hitBank][bi->hitBankIndex].ctr, taken,
559         if (gtable[bi->hitBank][bi->hitBankIndex].u == 0) {
560             if (bi->altBank > 0) {
561                 ctrUpdate(gtable[bi->altBank][bi->altBankIndex].ctr, taken,
564                         " branch %lx\n", bi->hitBank, bi->hitBankIndex,
567             if (bi->altBank == 0) {
568                 baseUpdate(branch_pc, taken, bi);
573         if (bi->tagePred != bi->altTaken) {
574             unsignedCtrUpdate(gtable[bi->hitBank][bi->hitBankIndex].u,
575                               bi->tagePred == taken, tagTableUBits);
578         baseUpdate(branch_pc, taken, bi);
584                           BranchInfo* bi, bool speculative,
600         bi->ptGhist = tHist.ptGhist;
601         bi->pathHist = tHist.pathHist;
608             bi->ci[i]  = tHist.computeIndices[i].comp;
609             bi->ct0[i] = tHist.computeTags[0][i].comp;
610             bi->ct1[i] = tHist.computeTags[1][i].comp;
624 TAGEBase::squash(ThreadID tid, bool taken, TAGEBase::BranchInfo *bi,
634             "pointer:%d\n", bi->branchPC,taken, bi->pathHist, bi->ptGhist);
635     tHist.pathHist = bi->pathHist;
636     tHist.ptGhist = bi->ptGhist;
640         tHist.computeIndices[i].comp = bi->ci[i];
641         tHist.computeTags[0][i].comp = bi->ct0[i];
642         tHist.computeTags[1][i].comp = bi->ct1[i];
650 TAGEBase::extraAltCalc(BranchInfo* bi)
657 TAGEBase::updateStats(bool taken, BranchInfo* bi)
659     if (taken == bi->tagePred) {
661         switch (bi->provider) {
669         switch (bi->provider) {
673             if (bi->altTaken == taken) {
685         switch (bi->provider) {
688             if (bi->longestMatchPred == taken) {
694     switch (bi->provider) {
697         tageLongestMatchProvider[bi->hitBank]++;
698         tageAltMatchProvider[bi->altBank]++;
704 TAGEBase::getGHR(ThreadID tid, BranchInfo *bi) const
709         int gh_offset = bi->ptGhist + i;