| /* |
| * Copyright (c) 2014 The University of Wisconsin |
| * |
| * Copyright (c) 2006 INRIA (Institut National de Recherche en |
| * Informatique et en Automatique / French National Research Institute |
| * for Computer Science and Applied Mathematics) |
| * |
| * 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. |
| */ |
| |
| /* @file |
| * Implementation of a TAGE branch predictor. TAGE is a global-history based |
| * branch predictor. It features a PC-indexed bimodal predictor and N |
| * partially tagged tables, indexed with a hash of the PC and the global |
| * branch history. The different lengths of global branch history used to |
| * index the partially tagged tables grow geometrically. A small path history |
| * is also used in the hash. |
| * |
| * All TAGE tables are accessed in parallel, and the one using the longest |
| * history that matches provides the prediction (some exceptions apply). |
| * Entries are allocated in components using a longer history than the |
| * one that predicted when the prediction is incorrect. |
| */ |
| |
| #ifndef __CPU_PRED_TAGE_HH__ |
| #define __CPU_PRED_TAGE_HH__ |
| |
| #include <vector> |
| |
| #include "base/types.hh" |
| #include "cpu/pred/bpred_unit.hh" |
| #include "cpu/pred/tage_base.hh" |
| #include "params/TAGE.hh" |
| |
| namespace gem5 |
| { |
| |
| namespace branch_prediction |
| { |
| |
| class TAGE: public BPredUnit |
| { |
| protected: |
| TAGEBase *tage; |
| |
| struct TageBranchInfo |
| { |
| TAGEBase::BranchInfo *tageBranchInfo; |
| |
| TageBranchInfo(TAGEBase &tage) : tageBranchInfo(tage.makeBranchInfo()) |
| {} |
| |
| virtual ~TageBranchInfo() |
| { |
| delete tageBranchInfo; |
| } |
| }; |
| |
| virtual bool predict(ThreadID tid, Addr branch_pc, bool cond_branch, |
| void* &b); |
| |
| public: |
| |
| TAGE(const TAGEParams ¶ms); |
| |
| // Base class methods. |
| void uncondBranch(ThreadID tid, Addr br_pc, void* &bp_history) override; |
| bool lookup(ThreadID tid, Addr branch_addr, void* &bp_history) override; |
| void btbUpdate(ThreadID tid, Addr branch_addr, void* &bp_history) override; |
| void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history, |
| bool squashed, const StaticInstPtr & inst, |
| Addr corrTarget) override; |
| virtual void squash(ThreadID tid, void *bp_history) override; |
| }; |
| |
| } // namespace branch_prediction |
| } // namespace gem5 |
| |
| #endif // __CPU_PRED_TAGE_HH__ |