ship_rp.cc

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#include "mem/cache/replacement_policies/ship_rp.hh"
 
#include "base/logging.hh"
#include "params/SHiPMemRP.hh"
#include "params/SHiPPCRP.hh"
#include "params/SHiPRP.hh"
 
namespace gem5
{
 
namespace replacement_policy
{
 
SHiP::SHiPReplData::SHiPReplData(int num_bits)
  : BRRIPReplData(num_bits), signature(0), outcome(false)
{
}
 
SHiP::SignatureType
SHiP::SHiPReplData::getSignature() const
{
    return signature;
}
 
void
SHiP::SHiPReplData::setSignature(SignatureType new_signature)
{
    signature = new_signature;
    outcome = false;
}
 
void
SHiP::SHiPReplData::setReReferenced()
{
    outcome = true;
}
 
bool
SHiP::SHiPReplData::wasReReferenced() const
{
    return outcome;
}
 
SHiP::SHiP(const Params &p)
  : BRRIP(p), insertionThreshold(p.insertion_threshold / 100.0),
    SHCT(p.shct_size, SatCounter(numRRPVBits))
{
}
 
void
SHiP::invalidate(const std::shared_ptr<ReplacementData>& replacement_data)
{
    std::shared_ptr<SHiPReplData> casted_replacement_data =
        std::static_pointer_cast<SHiPReplData>(replacement_data);
 
    // The predictor is detrained when an entry that has not been re-
    // referenced since insertion is invalidated
    if (casted_replacement_data->wasReReferenced()) {
        SHCT[casted_replacement_data->getSignature()]--;
    }
 
    BRRIP::invalidate(replacement_data);
}
 
void
SHiP::touch(const std::shared_ptr<ReplacementData>& replacement_data,
    const PacketPtr pkt)
{
    std::shared_ptr<SHiPReplData> casted_replacement_data =
        std::static_pointer_cast<SHiPReplData>(replacement_data);
 
    // When a hit happens the SHCT entry indexed by the signature is
    // incremented
    SHCT[getSignature(pkt)]++;
    casted_replacement_data->setReReferenced();
 
    // This was a hit; update replacement data accordingly
    BRRIP::touch(replacement_data);
}
 
void
SHiP::touch(const std::shared_ptr<ReplacementData>& replacement_data)
    const
{
    panic("Cant train SHiP's predictor without access information.");
}
 
void
SHiP::reset(const std::shared_ptr<ReplacementData>& replacement_data,
    const PacketPtr pkt)
{
    std::shared_ptr<SHiPReplData> casted_replacement_data =
        std::static_pointer_cast<SHiPReplData>(replacement_data);
 
    // Get signature
    const SignatureType signature = getSignature(pkt);
 
    // Store signature
    casted_replacement_data->setSignature(signature);
 
    // If SHCT for signature is set, predict intermediate re-reference.
    // Predict distant re-reference otherwise
    BRRIP::reset(replacement_data);
    if (SHCT[signature].calcSaturation() >= insertionThreshold) {
        casted_replacement_data->rrpv--;
    }
}
 
void
SHiP::reset(const std::shared_ptr<ReplacementData>& replacement_data)
    const
{
    panic("Cant train SHiP's predictor without access information.");
}
 
std::shared_ptr<ReplacementData>
SHiP::instantiateEntry()
{
    return std::shared_ptr<ReplacementData>(new SHiPReplData(numRRPVBits));
}
 
SHiPMem::SHiPMem(const SHiPMemRPParams &p) : SHiP(p) {}
 
SHiP::SignatureType
SHiPMem::getSignature(const PacketPtr pkt) const
{
    return static_cast<SignatureType>(pkt->getAddr() % SHCT.size());
}
 
SHiPPC::SHiPPC(const SHiPPCRPParams &p) : SHiP(p) {}
 
SHiP::SignatureType
SHiPPC::getSignature(const PacketPtr pkt) const
{
    SignatureType signature;
 
    if (pkt->req->hasPC()) {
        signature = static_cast<SignatureType>(pkt->req->getPC());
    } else {
        signature = NO_PC_SIGNATURE;
    }
 
    return signature % SHCT.size();
}
 
} // namespace replacement_policy
} // namespace gem5