src/gpu-compute/scalar_register_file.cc

/*
 * Copyright (c) 2015-2017 Advanced Micro Devices, Inc.
 * All rights reserved.
 *
 * For use for simulation and test purposes only
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. Neither the name of the copyright holder 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 HOLDER 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.
 *
 * Authors: John Kalamatianos,
 *          Mark Wyse
 */

#include "gpu-compute/scalar_register_file.hh"

#include "base/logging.hh"
#include "debug/GPUSRF.hh"
#include "gpu-compute/compute_unit.hh"
#include "gpu-compute/gpu_dyn_inst.hh"
#include "gpu-compute/shader.hh"
#include "gpu-compute/wavefront.hh"
#include "params/ScalarRegisterFile.hh"

ScalarRegisterFile::ScalarRegisterFile(const ScalarRegisterFileParams &p)
    : RegisterFile(p)
{
    regFile.resize(numRegs(), 0);
}

bool
ScalarRegisterFile::operandsReady(Wavefront *w, GPUDynInstPtr ii) const
{
    for (int i = 0; i < ii->getNumOperands(); ++i) {
        if (ii->isScalarRegister(i) && ii->isSrcOperand(i)) {

            int sgprIdx = ii->getRegisterIndex(i, ii);
            int nRegs = ii->getOperandSize(i) <= 4 ? 1 :
                ii->getOperandSize(i) / 4;

            for (int j = 0; j < nRegs; ++j) {
                int pSgpr =
                    computeUnit->registerManager->mapSgpr(w, sgprIdx + j);

                if (regBusy(pSgpr)) {
                    if (ii->isDstOperand(i)) {
                        w->numTimesBlockedDueWAXDependencies++;
                    } else if (ii->isSrcOperand(i)) {
                        DPRINTF(GPUSRF, "RAW stall: WV[%d]: %s: physReg[%d]\n",
                                w->wfDynId, ii->disassemble(), pSgpr);
                        w->numTimesBlockedDueRAWDependencies++;
                    }
                    return false;
                }
            } // nRegs
        } // isScalar
    } // operand
    return true;
}

void
ScalarRegisterFile::scheduleWriteOperands(Wavefront *w, GPUDynInstPtr ii)
{
    // iterate over all register destination operands
    for (int i = 0; i < ii->getNumOperands(); ++i) {
        if (ii->isScalarRegister(i) && ii->isDstOperand(i)) {

            int sgprIdx = ii->getRegisterIndex(i, ii);
            int nRegs = ii->getOperandSize(i) <= 4 ? 1 :
                ii->getOperandSize(i) / 4;

            for (int j = 0; j < nRegs; ++j) {
                int physReg =
                    computeUnit->registerManager->mapSgpr(w, sgprIdx + j);

                // mark the destination scalar register as busy
                markReg(physReg, true);
            }
        }
    }
}

void
ScalarRegisterFile::waveExecuteInst(Wavefront *w, GPUDynInstPtr ii)
{
    for (int i = 0; i < ii->getNumOperands(); i++) {
        if (ii->isScalarRegister(i) && ii->isSrcOperand(i)) {
            int DWORDs = ii->getOperandSize(i) <= 4 ? 1
                : ii->getOperandSize(i) / 4;
            registerReads += DWORDs;
        }
    }

    if (!ii->isLoad() && !(ii->isAtomic() || ii->isMemSync())) {
        Cycles delay(computeUnit->scalarPipeLength());
        Tick tickDelay = computeUnit->cyclesToTicks(delay);

        for (int i = 0; i < ii->getNumOperands(); i++) {
            if (ii->isScalarRegister(i) && ii->isDstOperand(i)) {
                int sgprIdx = ii->getRegisterIndex(i, ii);
                int nRegs = ii->getOperandSize(i) <= 4 ? 1
                    : ii->getOperandSize(i) / 4;
                for (int j = 0; j < nRegs; j++) {
                    int physReg = computeUnit->registerManager->
                        mapSgpr(w, sgprIdx + j);
                    enqRegFreeEvent(physReg, tickDelay);
                }

                registerWrites += nRegs;
            }
        }
    }
}

void
ScalarRegisterFile::scheduleWriteOperandsFromLoad(Wavefront *w,
                                                  GPUDynInstPtr ii)
{
    assert(ii->isLoad() || ii->isAtomicRet());
    for (int i = 0; i < ii->getNumOperands(); ++i) {
        if (ii->isScalarRegister(i) && ii->isDstOperand(i)) {

            int sgprIdx = ii->getRegisterIndex(i, ii);
            int nRegs = ii->getOperandSize(i) <= 4 ? 1 :
                ii->getOperandSize(i) / 4;

            for (int j = 0; j < nRegs; ++j) {
                int physReg = computeUnit->registerManager->
                    mapSgpr(w, sgprIdx + j);
                enqRegFreeEvent(physReg, computeUnit->clockPeriod());
            }

            registerWrites += nRegs;
        }
    }
}