ltage.hh revision 11784
111784Sarthur.perais@inria.fr/* 211784Sarthur.perais@inria.fr * Copyright (c) 2014 The University of Wisconsin 311784Sarthur.perais@inria.fr * 411784Sarthur.perais@inria.fr * Copyright (c) 2006 INRIA (Institut National de Recherche en 511784Sarthur.perais@inria.fr * Informatique et en Automatique / French National Research Institute 611784Sarthur.perais@inria.fr * for Computer Science and Applied Mathematics) 711784Sarthur.perais@inria.fr * 811784Sarthur.perais@inria.fr * All rights reserved. 911784Sarthur.perais@inria.fr * 1011784Sarthur.perais@inria.fr * Redistribution and use in source and binary forms, with or without 1111784Sarthur.perais@inria.fr * modification, are permitted provided that the following conditions are 1211784Sarthur.perais@inria.fr * met: redistributions of source code must retain the above copyright 1311784Sarthur.perais@inria.fr * notice, this list of conditions and the following disclaimer; 1411784Sarthur.perais@inria.fr * redistributions in binary form must reproduce the above copyright 1511784Sarthur.perais@inria.fr * notice, this list of conditions and the following disclaimer in the 1611784Sarthur.perais@inria.fr * documentation and/or other materials provided with the distribution; 1711784Sarthur.perais@inria.fr * neither the name of the copyright holders nor the names of its 1811784Sarthur.perais@inria.fr * contributors may be used to endorse or promote products derived from 1911784Sarthur.perais@inria.fr * this software without specific prior written permission. 2011784Sarthur.perais@inria.fr * 2111784Sarthur.perais@inria.fr * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 2211784Sarthur.perais@inria.fr * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 2311784Sarthur.perais@inria.fr * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 2411784Sarthur.perais@inria.fr * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 2511784Sarthur.perais@inria.fr * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 2611784Sarthur.perais@inria.fr * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 2711784Sarthur.perais@inria.fr * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 2811784Sarthur.perais@inria.fr * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 2911784Sarthur.perais@inria.fr * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 3011784Sarthur.perais@inria.fr * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 3111784Sarthur.perais@inria.fr * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 3211784Sarthur.perais@inria.fr * 3311784Sarthur.perais@inria.fr * Authors: Vignyan Reddy, Dibakar Gope and Arthur Perais, 3411784Sarthur.perais@inria.fr * from André Seznec's code. 3511784Sarthur.perais@inria.fr */ 3611784Sarthur.perais@inria.fr 3711784Sarthur.perais@inria.fr/* @file 3811784Sarthur.perais@inria.fr * Implementation of a L-TAGE branch predictor. TAGE is a global-history based 3911784Sarthur.perais@inria.fr * branch predictor. It features a PC-indexed bimodal predictor and N 4011784Sarthur.perais@inria.fr * partially tagged tables, indexed with a hash of the PC and the global 4111784Sarthur.perais@inria.fr * branch history. The different lengths of global branch history used to 4211784Sarthur.perais@inria.fr * index the partially tagged tables grow geometrically. A small path history 4311784Sarthur.perais@inria.fr * is also used in the hash. L-TAGE also features a loop predictor that records 4411784Sarthur.perais@inria.fr * iteration count of loops and predicts accordingly. 4511784Sarthur.perais@inria.fr * 4611784Sarthur.perais@inria.fr * All TAGE tables are accessed in parallel, and the one using the longest 4711784Sarthur.perais@inria.fr * history that matches provides the prediction (some exceptions apply). 4811784Sarthur.perais@inria.fr * Entries are allocated in components using a longer history than the 4911784Sarthur.perais@inria.fr * one that predicted when the prediction is incorrect. 5011784Sarthur.perais@inria.fr */ 5111784Sarthur.perais@inria.fr 5211784Sarthur.perais@inria.fr#ifndef __CPU_PRED_LTAGE 5311784Sarthur.perais@inria.fr#define __CPU_PRED_LTAGE 5411784Sarthur.perais@inria.fr 5511784Sarthur.perais@inria.fr#include <vector> 5611784Sarthur.perais@inria.fr 5711784Sarthur.perais@inria.fr#include "base/types.hh" 5811784Sarthur.perais@inria.fr#include "cpu/pred/bpred_unit.hh" 5911784Sarthur.perais@inria.fr#include "params/LTAGE.hh" 6011784Sarthur.perais@inria.fr 6111784Sarthur.perais@inria.frclass LTAGE: public BPredUnit 6211784Sarthur.perais@inria.fr{ 6311784Sarthur.perais@inria.fr public: 6411784Sarthur.perais@inria.fr LTAGE(const LTAGEParams *params); 6511784Sarthur.perais@inria.fr 6611784Sarthur.perais@inria.fr // Base class methods. 6711784Sarthur.perais@inria.fr void uncondBranch(ThreadID tid, Addr br_pc, void* &bp_history) override; 6811784Sarthur.perais@inria.fr bool lookup(ThreadID tid, Addr branch_addr, void* &bp_history) override; 6911784Sarthur.perais@inria.fr void btbUpdate(ThreadID tid, Addr branch_addr, void* &bp_history) override; 7011784Sarthur.perais@inria.fr void update(ThreadID tid, Addr branch_addr, bool taken, void *bp_history, 7111784Sarthur.perais@inria.fr bool squashed) override; 7211784Sarthur.perais@inria.fr void squash(ThreadID tid, void *bp_history) override; 7311784Sarthur.perais@inria.fr unsigned getGHR(ThreadID tid, void *bp_history) const override; 7411784Sarthur.perais@inria.fr 7511784Sarthur.perais@inria.fr private: 7611784Sarthur.perais@inria.fr // Prediction Structures 7711784Sarthur.perais@inria.fr // Loop Predictor Entry 7811784Sarthur.perais@inria.fr struct LoopEntry 7911784Sarthur.perais@inria.fr { 8011784Sarthur.perais@inria.fr uint16_t numIter; 8111784Sarthur.perais@inria.fr uint16_t currentIter; 8211784Sarthur.perais@inria.fr uint16_t currentIterSpec; 8311784Sarthur.perais@inria.fr uint8_t confidence; 8411784Sarthur.perais@inria.fr uint16_t tag; 8511784Sarthur.perais@inria.fr uint8_t age; 8611784Sarthur.perais@inria.fr bool dir; 8711784Sarthur.perais@inria.fr 8811784Sarthur.perais@inria.fr LoopEntry() : numIter(0), currentIter(0), currentIterSpec(0), 8911784Sarthur.perais@inria.fr confidence(0), tag(0), age(0), dir(0) { } 9011784Sarthur.perais@inria.fr }; 9111784Sarthur.perais@inria.fr 9211784Sarthur.perais@inria.fr // Bimodal Predictor Entry 9311784Sarthur.perais@inria.fr struct BimodalEntry 9411784Sarthur.perais@inria.fr { 9511784Sarthur.perais@inria.fr uint8_t pred; 9611784Sarthur.perais@inria.fr uint8_t hyst; 9711784Sarthur.perais@inria.fr 9811784Sarthur.perais@inria.fr BimodalEntry() : pred(0), hyst(1) { } 9911784Sarthur.perais@inria.fr }; 10011784Sarthur.perais@inria.fr 10111784Sarthur.perais@inria.fr // Tage Entry 10211784Sarthur.perais@inria.fr struct TageEntry 10311784Sarthur.perais@inria.fr { 10411784Sarthur.perais@inria.fr int8_t ctr; 10511784Sarthur.perais@inria.fr uint16_t tag; 10611784Sarthur.perais@inria.fr int8_t u; 10711784Sarthur.perais@inria.fr TageEntry() : ctr(0), tag(0), u(0) { } 10811784Sarthur.perais@inria.fr }; 10911784Sarthur.perais@inria.fr 11011784Sarthur.perais@inria.fr // Folded History Table - compressed history 11111784Sarthur.perais@inria.fr // to mix with instruction PC to index partially 11211784Sarthur.perais@inria.fr // tagged tables. 11311784Sarthur.perais@inria.fr struct FoldedHistory 11411784Sarthur.perais@inria.fr { 11511784Sarthur.perais@inria.fr unsigned comp; 11611784Sarthur.perais@inria.fr int compLength; 11711784Sarthur.perais@inria.fr int origLength; 11811784Sarthur.perais@inria.fr int outpoint; 11911784Sarthur.perais@inria.fr 12011784Sarthur.perais@inria.fr void init(int original_length, int compressed_length) 12111784Sarthur.perais@inria.fr { 12211784Sarthur.perais@inria.fr comp = 0; 12311784Sarthur.perais@inria.fr origLength = original_length; 12411784Sarthur.perais@inria.fr compLength = compressed_length; 12511784Sarthur.perais@inria.fr outpoint = original_length % compressed_length; 12611784Sarthur.perais@inria.fr } 12711784Sarthur.perais@inria.fr 12811784Sarthur.perais@inria.fr void update(uint8_t * h) 12911784Sarthur.perais@inria.fr { 13011784Sarthur.perais@inria.fr comp = (comp << 1) | h[0]; 13111784Sarthur.perais@inria.fr comp ^= h[origLength] << outpoint; 13211784Sarthur.perais@inria.fr comp ^= (comp >> compLength); 13311784Sarthur.perais@inria.fr comp &= (ULL(1) << compLength) - 1; 13411784Sarthur.perais@inria.fr } 13511784Sarthur.perais@inria.fr }; 13611784Sarthur.perais@inria.fr 13711784Sarthur.perais@inria.fr // Primary branch history entry 13811784Sarthur.perais@inria.fr struct BranchInfo 13911784Sarthur.perais@inria.fr { 14011784Sarthur.perais@inria.fr int pathHist; 14111784Sarthur.perais@inria.fr int ptGhist; 14211784Sarthur.perais@inria.fr int hitBank; 14311784Sarthur.perais@inria.fr int hitBankIndex; 14411784Sarthur.perais@inria.fr int altBank; 14511784Sarthur.perais@inria.fr int altBankIndex; 14611784Sarthur.perais@inria.fr int bimodalIndex; 14711784Sarthur.perais@inria.fr int loopTag; 14811784Sarthur.perais@inria.fr uint16_t currentIter; 14911784Sarthur.perais@inria.fr 15011784Sarthur.perais@inria.fr bool tagePred; 15111784Sarthur.perais@inria.fr bool altTaken; 15211784Sarthur.perais@inria.fr bool loopPred; 15311784Sarthur.perais@inria.fr bool loopPredValid; 15411784Sarthur.perais@inria.fr int loopIndex; 15511784Sarthur.perais@inria.fr int loopHit; 15611784Sarthur.perais@inria.fr bool condBranch; 15711784Sarthur.perais@inria.fr bool longestMatchPred; 15811784Sarthur.perais@inria.fr bool pseudoNewAlloc; 15911784Sarthur.perais@inria.fr Addr branchPC; 16011784Sarthur.perais@inria.fr 16111784Sarthur.perais@inria.fr // Pointer to dynamically allocated storage 16211784Sarthur.perais@inria.fr // to save table indices and folded histories. 16311784Sarthur.perais@inria.fr // To do one call to new instead of five. 16411784Sarthur.perais@inria.fr int *storage; 16511784Sarthur.perais@inria.fr 16611784Sarthur.perais@inria.fr // Pointers to actual saved array within the dynamically 16711784Sarthur.perais@inria.fr // allocated storage. 16811784Sarthur.perais@inria.fr int *tableIndices; 16911784Sarthur.perais@inria.fr int *tableTags; 17011784Sarthur.perais@inria.fr int *ci; 17111784Sarthur.perais@inria.fr int *ct0; 17211784Sarthur.perais@inria.fr int *ct1; 17311784Sarthur.perais@inria.fr 17411784Sarthur.perais@inria.fr BranchInfo(int sz) 17511784Sarthur.perais@inria.fr : pathHist(0), ptGhist(0), 17611784Sarthur.perais@inria.fr hitBank(0), hitBankIndex(0), 17711784Sarthur.perais@inria.fr altBank(0), altBankIndex(0), 17811784Sarthur.perais@inria.fr bimodalIndex(0), loopTag(0), currentIter(0), 17911784Sarthur.perais@inria.fr tagePred(false), altTaken(false), loopPred(false), 18011784Sarthur.perais@inria.fr loopPredValid(false), loopIndex(0), loopHit(0), 18111784Sarthur.perais@inria.fr condBranch(false), longestMatchPred(false), 18211784Sarthur.perais@inria.fr pseudoNewAlloc(false), branchPC(0) 18311784Sarthur.perais@inria.fr { 18411784Sarthur.perais@inria.fr storage = new int [sz * 5]; 18511784Sarthur.perais@inria.fr tableIndices = storage; 18611784Sarthur.perais@inria.fr tableTags = storage + sz; 18711784Sarthur.perais@inria.fr ci = tableTags + sz; 18811784Sarthur.perais@inria.fr ct0 = ci + sz; 18911784Sarthur.perais@inria.fr ct1 = ct0 + sz; 19011784Sarthur.perais@inria.fr } 19111784Sarthur.perais@inria.fr 19211784Sarthur.perais@inria.fr ~BranchInfo() 19311784Sarthur.perais@inria.fr { 19411784Sarthur.perais@inria.fr delete[] storage; 19511784Sarthur.perais@inria.fr } 19611784Sarthur.perais@inria.fr }; 19711784Sarthur.perais@inria.fr 19811784Sarthur.perais@inria.fr /** 19911784Sarthur.perais@inria.fr * Computes the index used to access the 20011784Sarthur.perais@inria.fr * bimodal table. 20111784Sarthur.perais@inria.fr * @param pc_in The unshifted branch PC. 20211784Sarthur.perais@inria.fr */ 20311784Sarthur.perais@inria.fr int bindex(Addr pc_in) const; 20411784Sarthur.perais@inria.fr 20511784Sarthur.perais@inria.fr /** 20611784Sarthur.perais@inria.fr * Computes the index used to access the 20711784Sarthur.perais@inria.fr * loop predictor. 20811784Sarthur.perais@inria.fr * @param pc_in The unshifted branch PC. 20911784Sarthur.perais@inria.fr */ 21011784Sarthur.perais@inria.fr int lindex(Addr pc_in) const; 21111784Sarthur.perais@inria.fr 21211784Sarthur.perais@inria.fr /** 21311784Sarthur.perais@inria.fr * Computes the index used to access a 21411784Sarthur.perais@inria.fr * partially tagged table. 21511784Sarthur.perais@inria.fr * @param tid The thread ID used to select the 21611784Sarthur.perais@inria.fr * global histories to use. 21711784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 21811784Sarthur.perais@inria.fr * @param bank The partially tagged table to access. 21911784Sarthur.perais@inria.fr */ 22011784Sarthur.perais@inria.fr inline int gindex(ThreadID tid, Addr pc, int bank) const; 22111784Sarthur.perais@inria.fr 22211784Sarthur.perais@inria.fr /** 22311784Sarthur.perais@inria.fr * Utility function to shuffle the path history 22411784Sarthur.perais@inria.fr * depending on which tagged table we are accessing. 22511784Sarthur.perais@inria.fr * @param phist The path history. 22611784Sarthur.perais@inria.fr * @param size Number of path history bits to use. 22711784Sarthur.perais@inria.fr * @param bank The partially tagged table to access. 22811784Sarthur.perais@inria.fr */ 22911784Sarthur.perais@inria.fr int F(int phist, int size, int bank) const; 23011784Sarthur.perais@inria.fr 23111784Sarthur.perais@inria.fr /** 23211784Sarthur.perais@inria.fr * Computes the partial tag of a tagged table. 23311784Sarthur.perais@inria.fr * @param tid the thread ID used to select the 23411784Sarthur.perais@inria.fr * global histories to use. 23511784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 23611784Sarthur.perais@inria.fr * @param bank The partially tagged table to access. 23711784Sarthur.perais@inria.fr */ 23811784Sarthur.perais@inria.fr inline uint16_t gtag(ThreadID tid, Addr pc, int bank) const; 23911784Sarthur.perais@inria.fr 24011784Sarthur.perais@inria.fr /** 24111784Sarthur.perais@inria.fr * Updates a direction counter based on the actual 24211784Sarthur.perais@inria.fr * branch outcome. 24311784Sarthur.perais@inria.fr * @param ctr Reference to counter to update. 24411784Sarthur.perais@inria.fr * @param taken Actual branch outcome. 24511784Sarthur.perais@inria.fr * @param nbits Counter width. 24611784Sarthur.perais@inria.fr */ 24711784Sarthur.perais@inria.fr void ctrUpdate(int8_t & ctr, bool taken, int nbits); 24811784Sarthur.perais@inria.fr 24911784Sarthur.perais@inria.fr /** 25011784Sarthur.perais@inria.fr * Get a branch prediction from the bimodal 25111784Sarthur.perais@inria.fr * predictor. 25211784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 25311784Sarthur.perais@inria.fr * @param bi Pointer to information on the 25411784Sarthur.perais@inria.fr * prediction. 25511784Sarthur.perais@inria.fr */ 25611784Sarthur.perais@inria.fr bool getBimodePred(Addr pc, BranchInfo* bi) const; 25711784Sarthur.perais@inria.fr 25811784Sarthur.perais@inria.fr /** 25911784Sarthur.perais@inria.fr * Updates the bimodal predictor. 26011784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 26111784Sarthur.perais@inria.fr * @param taken The actual branch outcome. 26211784Sarthur.perais@inria.fr * @param bi Pointer to information on the prediction 26311784Sarthur.perais@inria.fr * recorded at prediction time. 26411784Sarthur.perais@inria.fr */ 26511784Sarthur.perais@inria.fr void baseUpdate(Addr pc, bool taken, BranchInfo* bi); 26611784Sarthur.perais@inria.fr 26711784Sarthur.perais@inria.fr /** 26811784Sarthur.perais@inria.fr * Get a branch prediction from the loop 26911784Sarthur.perais@inria.fr * predictor. 27011784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 27111784Sarthur.perais@inria.fr * @param bi Pointer to information on the 27211784Sarthur.perais@inria.fr * prediction. 27311784Sarthur.perais@inria.fr */ 27411784Sarthur.perais@inria.fr bool getLoop(Addr pc, BranchInfo* bi) const; 27511784Sarthur.perais@inria.fr 27611784Sarthur.perais@inria.fr /** 27711784Sarthur.perais@inria.fr * Updates the loop predictor. 27811784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 27911784Sarthur.perais@inria.fr * @param taken The actual branch outcome. 28011784Sarthur.perais@inria.fr * @param bi Pointer to information on the 28111784Sarthur.perais@inria.fr * prediction recorded at prediction time. 28211784Sarthur.perais@inria.fr */ 28311784Sarthur.perais@inria.fr void loopUpdate(Addr pc, bool Taken, BranchInfo* bi); 28411784Sarthur.perais@inria.fr 28511784Sarthur.perais@inria.fr /** 28611784Sarthur.perais@inria.fr * (Speculatively) updates the global branch history. 28711784Sarthur.perais@inria.fr * @param h Reference to pointer to global branch history. 28811784Sarthur.perais@inria.fr * @param dir (Predicted) outcome to update the histories 28911784Sarthur.perais@inria.fr * with. 29011784Sarthur.perais@inria.fr * @param tab 29111784Sarthur.perais@inria.fr * @param PT Reference to path history. 29211784Sarthur.perais@inria.fr */ 29311784Sarthur.perais@inria.fr void updateGHist(uint8_t * &h, bool dir, uint8_t * tab, int &PT); 29411784Sarthur.perais@inria.fr 29511784Sarthur.perais@inria.fr /** 29611784Sarthur.perais@inria.fr * Get a branch prediction from L-TAGE. *NOT* an override of 29711784Sarthur.perais@inria.fr * BpredUnit::predict(). 29811784Sarthur.perais@inria.fr * @param tid The thread ID to select the global 29911784Sarthur.perais@inria.fr * histories to use. 30011784Sarthur.perais@inria.fr * @param branch_pc The unshifted branch PC. 30111784Sarthur.perais@inria.fr * @param cond_branch True if the branch is conditional. 30211784Sarthur.perais@inria.fr * @param b Reference to wrapping pointer to allow storing 30311784Sarthur.perais@inria.fr * derived class prediction information in the base class. 30411784Sarthur.perais@inria.fr */ 30511784Sarthur.perais@inria.fr bool predict(ThreadID tid, Addr branch_pc, bool cond_branch, void* &b); 30611784Sarthur.perais@inria.fr 30711784Sarthur.perais@inria.fr /** 30811784Sarthur.perais@inria.fr * Update L-TAGE. Called at execute to repair histories on a misprediction 30911784Sarthur.perais@inria.fr * and at commit to update the tables. 31011784Sarthur.perais@inria.fr * @param tid The thread ID to select the global 31111784Sarthur.perais@inria.fr * histories to use. 31211784Sarthur.perais@inria.fr * @param branch_pc The unshifted branch PC. 31311784Sarthur.perais@inria.fr * @param taken Actual branch outcome. 31411784Sarthur.perais@inria.fr * @param bi Pointer to information on the prediction 31511784Sarthur.perais@inria.fr * recorded at prediction time. 31611784Sarthur.perais@inria.fr */ 31711784Sarthur.perais@inria.fr void update(ThreadID tid, Addr branch_pc, bool taken, BranchInfo* bi); 31811784Sarthur.perais@inria.fr 31911784Sarthur.perais@inria.fr /** 32011784Sarthur.perais@inria.fr * (Speculatively) updates global histories (path and direction). 32111784Sarthur.perais@inria.fr * Also recomputes compressed (folded) histories based on the 32211784Sarthur.perais@inria.fr * branch direction. 32311784Sarthur.perais@inria.fr * @param tid The thread ID to select the histories 32411784Sarthur.perais@inria.fr * to update. 32511784Sarthur.perais@inria.fr * @param branch_pc The unshifted branch PC. 32611784Sarthur.perais@inria.fr * @param taken (Predicted) branch direction. 32711784Sarthur.perais@inria.fr * @param b Wrapping pointer to BranchInfo (to allow 32811784Sarthur.perais@inria.fr * storing derived class prediction information in the 32911784Sarthur.perais@inria.fr * base class). 33011784Sarthur.perais@inria.fr */ 33111784Sarthur.perais@inria.fr void updateHistories(ThreadID tid, Addr branch_pc, bool taken, void* b); 33211784Sarthur.perais@inria.fr 33311784Sarthur.perais@inria.fr /** 33411784Sarthur.perais@inria.fr * Restores speculatively updated path and direction histories. 33511784Sarthur.perais@inria.fr * Also recomputes compressed (folded) histories based on the 33611784Sarthur.perais@inria.fr * correct branch outcome. 33711784Sarthur.perais@inria.fr * This version of squash() is called once on a branch misprediction. 33811784Sarthur.perais@inria.fr * @param tid The Thread ID to select the histories to rollback. 33911784Sarthur.perais@inria.fr * @param taken The correct branch outcome. 34011784Sarthur.perais@inria.fr * @param bp_history Wrapping pointer to BranchInfo (to allow 34111784Sarthur.perais@inria.fr * storing derived class prediction information in the 34211784Sarthur.perais@inria.fr * base class). 34311784Sarthur.perais@inria.fr * @post bp_history points to valid memory. 34411784Sarthur.perais@inria.fr */ 34511784Sarthur.perais@inria.fr void squash(ThreadID tid, bool taken, void *bp_history); 34611784Sarthur.perais@inria.fr 34711784Sarthur.perais@inria.fr /** 34811784Sarthur.perais@inria.fr * Speculatively updates the loop predictor 34911784Sarthur.perais@inria.fr * iteration count. 35011784Sarthur.perais@inria.fr * @param pc The unshifted branch PC. 35111784Sarthur.perais@inria.fr * @param taken The predicted branch outcome. 35211784Sarthur.perais@inria.fr * @param bi Pointer to information on the prediction 35311784Sarthur.perais@inria.fr * recorded at prediction time. 35411784Sarthur.perais@inria.fr */ 35511784Sarthur.perais@inria.fr void specLoopUpdate(Addr pc, bool taken, BranchInfo* bi); 35611784Sarthur.perais@inria.fr 35711784Sarthur.perais@inria.fr const unsigned logSizeBiMP; 35811784Sarthur.perais@inria.fr const unsigned logSizeTagTables; 35911784Sarthur.perais@inria.fr const unsigned logSizeLoopPred; 36011784Sarthur.perais@inria.fr const unsigned nHistoryTables; 36111784Sarthur.perais@inria.fr const unsigned tagTableCounterBits; 36211784Sarthur.perais@inria.fr const unsigned histBufferSize; 36311784Sarthur.perais@inria.fr const unsigned minHist; 36411784Sarthur.perais@inria.fr const unsigned maxHist; 36511784Sarthur.perais@inria.fr const unsigned minTagWidth; 36611784Sarthur.perais@inria.fr 36711784Sarthur.perais@inria.fr BimodalEntry *btable; 36811784Sarthur.perais@inria.fr TageEntry **gtable; 36911784Sarthur.perais@inria.fr LoopEntry *ltable; 37011784Sarthur.perais@inria.fr 37111784Sarthur.perais@inria.fr // Keep per-thread histories to 37211784Sarthur.perais@inria.fr // support SMT. 37311784Sarthur.perais@inria.fr struct ThreadHistory { 37411784Sarthur.perais@inria.fr // Speculative path history 37511784Sarthur.perais@inria.fr // (LSB of branch address) 37611784Sarthur.perais@inria.fr int pathHist; 37711784Sarthur.perais@inria.fr 37811784Sarthur.perais@inria.fr // Speculative branch direction 37911784Sarthur.perais@inria.fr // history (circular buffer) 38011784Sarthur.perais@inria.fr // @TODO Convert to std::vector<bool> 38111784Sarthur.perais@inria.fr uint8_t *globalHistory; 38211784Sarthur.perais@inria.fr 38311784Sarthur.perais@inria.fr // Pointer to most recent branch outcome 38411784Sarthur.perais@inria.fr uint8_t* gHist; 38511784Sarthur.perais@inria.fr 38611784Sarthur.perais@inria.fr // Index to most recent branch outcome 38711784Sarthur.perais@inria.fr int ptGhist; 38811784Sarthur.perais@inria.fr 38911784Sarthur.perais@inria.fr // Speculative folded histories. 39011784Sarthur.perais@inria.fr FoldedHistory *computeIndices; 39111784Sarthur.perais@inria.fr FoldedHistory *computeTags[2]; 39211784Sarthur.perais@inria.fr }; 39311784Sarthur.perais@inria.fr 39411784Sarthur.perais@inria.fr std::vector<ThreadHistory> threadHistory; 39511784Sarthur.perais@inria.fr 39611784Sarthur.perais@inria.fr int tagWidths[15]; 39711784Sarthur.perais@inria.fr int tagTableSizes[15]; 39811784Sarthur.perais@inria.fr int *histLengths; 39911784Sarthur.perais@inria.fr int *tableIndices; 40011784Sarthur.perais@inria.fr int *tableTags; 40111784Sarthur.perais@inria.fr 40211784Sarthur.perais@inria.fr int8_t loopUseCounter; 40311784Sarthur.perais@inria.fr int8_t useAltPredForNewlyAllocated; 40411784Sarthur.perais@inria.fr int tCounter; 40511784Sarthur.perais@inria.fr int logTick; 40611784Sarthur.perais@inria.fr}; 40711784Sarthur.perais@inria.fr 40811784Sarthur.perais@inria.fr#endif // __CPU_PRED_LTAGE 409