store_set.cc

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/*
 * Copyright (c) 2004-2006 The Regents of The University of Michigan
 * All rights reserved.
 *
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 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
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 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#include "base/intmath.hh"
#include "base/logging.hh"
#include "base/trace.hh"
#include "cpu/o3/store_set.hh"
#include "debug/StoreSet.hh"
#include "mem/cache/tags/indexing_policies/base.hh"
#include "mem/cache/replacement_policies/base.hh"
 
namespace gem5
{
 
namespace o3
{
 
StoreSet::StoreSet(std::string_view name_, uint64_t clear_period,
                   size_t _SSIT_entries, int _SSIT_assoc,
                   replacement_policy::Base *_replPolicy,
                   BaseIndexingPolicy *_indexingPolicy, int _LFST_size)
  : Named(name_),
    SSIT("SSIT", _SSIT_entries, _SSIT_assoc,
         _replPolicy, _indexingPolicy,
         SSITEntry(genTagExtractor(_indexingPolicy))),
    clearPeriod(clear_period), SSITSize(_SSIT_entries),
    LFSTSize(_LFST_size)
{
    DPRINTF(StoreSet, "StoreSet: Creating store set object.\n");
    DPRINTF(StoreSet, "StoreSet: SSIT size: %i, LFST size: %i.\n",
            SSITSize, LFSTSize);
 
    if (!isPowerOf2(SSITSize)) {
        fatal("Invalid SSIT size!\n");
    }
 
    if (!isPowerOf2(LFSTSize)) {
        fatal("Invalid LFST size!\n");
    }
 
    LFST.resize(LFSTSize);
 
    validLFST.resize(LFSTSize);
 
    for (int i = 0; i < LFSTSize; ++i) {
        validLFST[i] = false;
        LFST[i] = 0;
    }
 
    memOpsPred = 0;
}
 
StoreSet::~StoreSet()
{
}
 
void
StoreSet::init(uint64_t clear_period, size_t _SSIT_entries,
               int _SSIT_assoc, replacement_policy::Base *_replPolicy,
               BaseIndexingPolicy *_indexingPolicy, int _LFST_size)
{
    SSITSize = _SSIT_entries;
    LFSTSize = _LFST_size;
    clearPeriod = clear_period;
 
    DPRINTF(StoreSet, "StoreSet: Creating store set object.\n");
    DPRINTF(StoreSet, "StoreSet: SSIT size: %i, LFST size: %i.\n",
            SSITSize, LFSTSize);
 
    SSIT.init(SSITSize, _SSIT_assoc, _replPolicy, _indexingPolicy,
              SSITEntry(genTagExtractor(_indexingPolicy)));
 
    LFST.resize(LFSTSize);
 
    validLFST.resize(LFSTSize);
 
    for (int i = 0; i < LFSTSize; ++i) {
        validLFST[i] = false;
        LFST[i] = 0;
    }
 
    memOpsPred = 0;
}
 
 
void
StoreSet::violation(Addr store_PC, Addr load_PC)
{
    auto ld_entry = SSIT.findEntry({load_PC});
    auto st_entry = SSIT.findEntry({store_PC});
 
    bool valid_load_SSID  = ld_entry && ld_entry->isValid();
    bool valid_store_SSID = st_entry && st_entry->isValid();
 
    if (!valid_load_SSID && !valid_store_SSID) {
        // Calculate a new SSID here.
        SSID new_set = calcSSID(load_PC);
 
        assert(new_set < LFSTSize);
 
        SSITEntry *ld_entry = SSIT.findVictim({load_PC});
        ld_entry->setSSID(new_set);
        SSIT.insertEntry({load_PC}, ld_entry);
 
        SSITEntry *st_entry = SSIT.findVictim({store_PC});
        st_entry->setSSID(new_set);
        SSIT.insertEntry({store_PC}, st_entry);
 
        DPRINTF(StoreSet, "StoreSet: Neither load nor store had a valid "
                "storeset, creating a new one: %i for load %#x, store %#x\n",
                new_set, load_PC, store_PC);
    } else if (valid_load_SSID && !valid_store_SSID) {
        SSID load_SSID = ld_entry->getSSID();
        SSITEntry *st_entry = SSIT.findVictim({store_PC});
        st_entry->setSSID(load_SSID);
        SSIT.insertEntry({store_PC}, st_entry);
 
        assert(load_SSID < LFSTSize);
 
        DPRINTF(StoreSet, "StoreSet: Load had a valid store set.  Adding "
                "store to that set: %i for load %#x, store %#x\n",
                load_SSID, load_PC, store_PC);
    } else if (!valid_load_SSID && valid_store_SSID) {
        SSID store_SSID = st_entry->getSSID();
        SSITEntry *ld_entry = SSIT.findVictim({load_PC});
        ld_entry->setSSID(store_SSID);
        SSIT.insertEntry({load_PC}, ld_entry);
 
        DPRINTF(StoreSet, "StoreSet: Store had a valid store set: %i for "
                "load %#x, store %#x\n",
                store_SSID, load_PC, store_PC);
    } else {
        SSID load_SSID = ld_entry->getSSID();
        SSID store_SSID = st_entry->getSSID();
 
        assert(load_SSID < LFSTSize && store_SSID < LFSTSize);
 
        // The store set with the lower number wins
        if (store_SSID > load_SSID) {
            st_entry->setSSID(load_SSID);
 
            DPRINTF(StoreSet, "StoreSet: Load had smaller store set: %i; "
                    "for load %#x, store %#x\n",
                    load_SSID, load_PC, store_PC);
        } else {
            ld_entry->setSSID(store_SSID);
 
            DPRINTF(StoreSet, "StoreSet: Store had smaller store set: %i; "
                    "for load %#x, store %#x\n",
                    store_SSID, load_PC, store_PC);
        }
    }
}
 
void
StoreSet::checkClear()
{
    memOpsPred++;
    if (memOpsPred > clearPeriod) {
        DPRINTF(StoreSet, "Wiping predictor state beacuse %d ld/st executed\n",
                clearPeriod);
        memOpsPred = 0;
        clear();
    }
}
 
void
StoreSet::insertLoad(Addr load_PC, InstSeqNum load_seq_num)
{
    checkClear();
    // Does nothing.
    return;
}
 
void
StoreSet::insertStore(Addr store_PC, InstSeqNum store_seq_num, ThreadID tid)
{
    auto st_entry = SSIT.findEntry({store_PC});
 
    bool valid_entry = st_entry && st_entry->isValid();
 
    int store_SSID;
 
    checkClear();
 
    if (!valid_entry) {
        // Do nothing if there's no valid entry.
        return;
    } else {
        store_SSID = st_entry->getSSID();
 
        assert(store_SSID < LFSTSize);
 
        // Update the last store that was fetched with the current one.
        LFST[store_SSID] = store_seq_num;
 
        validLFST[store_SSID] = 1;
 
        storeList[store_seq_num] = store_SSID;
 
        DPRINTF(StoreSet, "Store %#x updated the LFST, SSID: %i\n",
                store_PC, store_SSID);
    }
}
 
InstSeqNum
StoreSet::checkInst(Addr PC)
{
    auto entry = SSIT.findEntry({PC});
    bool valid_ssit = entry && entry->isValid();
 
    int inst_SSID;
 
    if (!valid_ssit) {
        DPRINTF(StoreSet, "Inst %#x has no SSID\n", PC);
 
        // Return 0 if there's no valid entry.
        return 0;
    } else {
        inst_SSID = entry->getSSID();
 
        assert(inst_SSID < LFSTSize);
 
        if (!validLFST[inst_SSID]) {
 
            DPRINTF(StoreSet, "Inst %#x with SSID %i had no "
                    "dependency\n", PC, inst_SSID);
 
            return 0;
        } else {
            DPRINTF(StoreSet, "Inst %#x with SSID %i had LFST "
                    "inum of %i\n", PC, inst_SSID, LFST[inst_SSID]);
 
            return LFST[inst_SSID];
        }
    }
}
 
void
StoreSet::issued(Addr issued_PC, InstSeqNum issued_seq_num, bool is_store)
{
    // This only is updated upon a store being issued.
    if (!is_store) {
        return;
    }
 
    auto entry = SSIT.findEntry({issued_PC});
    bool valid_ssit = entry && entry->isValid();
 
    int store_SSID;
 
    SeqNumMapIt store_list_it = storeList.find(issued_seq_num);
 
    if (store_list_it != storeList.end()) {
        storeList.erase(store_list_it);
    }
 
    // Make sure the SSIT still has a valid entry for the issued store.
    if (!valid_ssit) {
        return;
    }
 
    store_SSID = entry->getSSID();
 
    assert(store_SSID < LFSTSize);
 
    // If the last fetched store in the store set refers to the store that
    // was just issued, then invalidate the entry.
    if (validLFST[store_SSID] && LFST[store_SSID] == issued_seq_num) {
        DPRINTF(StoreSet, "StoreSet: store invalidated itself in LFST.\n");
        validLFST[store_SSID] = false;
    }
}
 
void
StoreSet::squash(InstSeqNum squashed_num, ThreadID tid)
{
    DPRINTF(StoreSet, "StoreSet: Squashing until inum %i\n",
            squashed_num);
 
    int idx;
    SeqNumMapIt store_list_it = storeList.begin();
 
    //@todo:Fix to only delete from correct thread
    while (!storeList.empty()) {
        idx = (*store_list_it).second;
 
        if ((*store_list_it).first <= squashed_num) {
            break;
        }
 
        bool younger = LFST[idx] > squashed_num;
 
        if (validLFST[idx] && younger) {
            DPRINTF(StoreSet, "Squashed [sn:%lli]\n", LFST[idx]);
            validLFST[idx] = false;
 
            storeList.erase(store_list_it++);
        } else if (!validLFST[idx] && younger) {
            storeList.erase(store_list_it++);
        }
    }
}
 
void
StoreSet::clear()
{
    SSIT.clear();
 
    for (int i = 0; i < LFSTSize; ++i) {
        validLFST[i] = false;
    }
 
    storeList.clear();
}
 
void
StoreSet::dump()
{
    cprintf("storeList.size(): %i\n", storeList.size());
    SeqNumMapIt store_list_it = storeList.begin();
 
    int num = 0;
 
    while (store_list_it != storeList.end()) {
        cprintf("%i: [sn:%lli] SSID:%i\n",
                num, (*store_list_it).first, (*store_list_it).second);
        num++;
        store_list_it++;
    }
}
 
} // namespace o3
} // namespace gem5