be28d96510
The following patches had unexpected interactions with the current upstream code and have been reverted for now: e07fd01651f3: power: Add support for power models 831c7f2f9e39: power: Low-power idle power state for idle CPUs 4f749e00b667: power: Add power states to ClockedObject Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com> --HG-- extra : amend_source : 0b6fb073c6bbc24be533ec431eb51fbf1b269508
164 lines
4.6 KiB
C++
164 lines
4.6 KiB
C++
/*
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* Copyright (c) 2004-2006 The Regents of The University of Michigan
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met: redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer;
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* redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution;
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* neither the name of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* Authors: Kevin Lim
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*/
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#include "base/intmath.hh"
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#include "base/misc.hh"
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#include "base/trace.hh"
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#include "cpu/pred/2bit_local.hh"
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#include "debug/Fetch.hh"
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LocalBP::LocalBP(const LocalBPParams *params)
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: BPredUnit(params),
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localPredictorSize(params->localPredictorSize),
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localCtrBits(params->localCtrBits)
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{
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if (!isPowerOf2(localPredictorSize)) {
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fatal("Invalid local predictor size!\n");
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}
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localPredictorSets = localPredictorSize / localCtrBits;
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if (!isPowerOf2(localPredictorSets)) {
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fatal("Invalid number of local predictor sets! Check localCtrBits.\n");
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}
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// Setup the index mask.
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indexMask = localPredictorSets - 1;
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DPRINTF(Fetch, "index mask: %#x\n", indexMask);
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// Setup the array of counters for the local predictor.
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localCtrs.resize(localPredictorSets);
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for (unsigned i = 0; i < localPredictorSets; ++i)
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localCtrs[i].setBits(localCtrBits);
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DPRINTF(Fetch, "local predictor size: %i\n",
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localPredictorSize);
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DPRINTF(Fetch, "local counter bits: %i\n", localCtrBits);
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DPRINTF(Fetch, "instruction shift amount: %i\n",
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instShiftAmt);
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}
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void
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LocalBP::reset()
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{
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for (unsigned i = 0; i < localPredictorSets; ++i) {
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localCtrs[i].reset();
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}
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}
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void
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LocalBP::btbUpdate(Addr branch_addr, void * &bp_history)
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{
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// Place holder for a function that is called to update predictor history when
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// a BTB entry is invalid or not found.
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}
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bool
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LocalBP::lookup(Addr branch_addr, void * &bp_history)
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{
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bool taken;
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uint8_t counter_val;
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unsigned local_predictor_idx = getLocalIndex(branch_addr);
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DPRINTF(Fetch, "Looking up index %#x\n",
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local_predictor_idx);
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counter_val = localCtrs[local_predictor_idx].read();
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DPRINTF(Fetch, "prediction is %i.\n",
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(int)counter_val);
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taken = getPrediction(counter_val);
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#if 0
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// Speculative update.
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if (taken) {
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DPRINTF(Fetch, "Branch updated as taken.\n");
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localCtrs[local_predictor_idx].increment();
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} else {
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DPRINTF(Fetch, "Branch updated as not taken.\n");
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localCtrs[local_predictor_idx].decrement();
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}
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#endif
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return taken;
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}
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void
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LocalBP::update(Addr branch_addr, bool taken, void *bp_history, bool squashed)
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{
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assert(bp_history == NULL);
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unsigned local_predictor_idx;
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// Update the local predictor.
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local_predictor_idx = getLocalIndex(branch_addr);
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DPRINTF(Fetch, "Looking up index %#x\n", local_predictor_idx);
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if (taken) {
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DPRINTF(Fetch, "Branch updated as taken.\n");
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localCtrs[local_predictor_idx].increment();
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} else {
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DPRINTF(Fetch, "Branch updated as not taken.\n");
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localCtrs[local_predictor_idx].decrement();
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}
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}
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inline
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bool
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LocalBP::getPrediction(uint8_t &count)
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{
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// Get the MSB of the count
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return (count >> (localCtrBits - 1));
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}
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inline
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unsigned
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LocalBP::getLocalIndex(Addr &branch_addr)
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{
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return (branch_addr >> instShiftAmt) & indexMask;
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}
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void
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LocalBP::uncondBranch(Addr pc, void *&bp_history)
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{
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}
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LocalBP*
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LocalBPParams::create()
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{
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return new LocalBP(this);
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}
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