2014-07-23 23:09:04 +02:00
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/*
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* Copyright (c) 2013-2014 ARM Limited
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* All rights reserved
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*
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* The license below extends only to copyright in the software and shall
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* not be construed as granting a license to any other intellectual
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* property including but not limited to intellectual property relating
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* to a hardware implementation of the functionality of the software
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* licensed hereunder. You may use the software subject to the license
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* terms below provided that you ensure that this notice is replicated
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* unmodified and in its entirety in all distributions of the software,
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* modified or unmodified, in source code or in binary form.
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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: Andrew Bardsley
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*/
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#include "cpu/minor/decode.hh"
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#include "cpu/minor/pipeline.hh"
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#include "debug/Decode.hh"
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namespace Minor
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{
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Decode::Decode(const std::string &name,
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MinorCPU &cpu_,
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MinorCPUParams ¶ms,
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Latch<ForwardInstData>::Output inp_,
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Latch<ForwardInstData>::Input out_,
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Reservable &next_stage_input_buffer) :
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Named(name),
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cpu(cpu_),
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inp(inp_),
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out(out_),
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nextStageReserve(next_stage_input_buffer),
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outputWidth(params.executeInputWidth),
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processMoreThanOneInput(params.decodeCycleInput),
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inputBuffer(name + ".inputBuffer", "insts", params.decodeInputBufferSize),
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inputIndex(0),
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inMacroop(false),
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2014-11-14 09:53:51 +01:00
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execSeqNum(InstId::firstExecSeqNum),
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blocked(false)
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2014-07-23 23:09:04 +02:00
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{
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if (outputWidth < 1)
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fatal("%s: executeInputWidth must be >= 1 (%d)\n", name, outputWidth);
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if (params.decodeInputBufferSize < 1) {
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fatal("%s: decodeInputBufferSize must be >= 1 (%d)\n", name,
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params.decodeInputBufferSize);
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}
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}
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const ForwardInstData *
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Decode::getInput()
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{
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/* Get insts from the inputBuffer to work with */
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if (!inputBuffer.empty()) {
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const ForwardInstData &head = inputBuffer.front();
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return (head.isBubble() ? NULL : &(inputBuffer.front()));
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} else {
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return NULL;
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}
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}
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void
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Decode::popInput()
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{
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if (!inputBuffer.empty())
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inputBuffer.pop();
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inputIndex = 0;
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inMacroop = false;
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}
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#if TRACING_ON
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/** Add the tracing data to an instruction. This originates in
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* decode because this is the first place that execSeqNums are known
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* (these are used as the 'FetchSeq' in tracing data) */
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static void
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dynInstAddTracing(MinorDynInstPtr inst, StaticInstPtr static_inst,
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MinorCPU &cpu)
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{
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inst->traceData = cpu.getTracer()->getInstRecord(curTick(),
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cpu.getContext(inst->id.threadId),
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inst->staticInst, inst->pc, static_inst);
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/* Use the execSeqNum as the fetch sequence number as this most closely
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* matches the other processor models' idea of fetch sequence */
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if (inst->traceData)
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inst->traceData->setFetchSeq(inst->id.execSeqNum);
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}
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#endif
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void
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Decode::evaluate()
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{
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inputBuffer.setTail(*inp.outputWire);
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ForwardInstData &insts_out = *out.inputWire;
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assert(insts_out.isBubble());
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blocked = false;
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if (!nextStageReserve.canReserve()) {
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blocked = true;
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} else {
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const ForwardInstData *insts_in = getInput();
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unsigned int output_index = 0;
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/* Pack instructions into the output while we can. This may involve
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* using more than one input line */
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while (insts_in &&
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inputIndex < insts_in->width() && /* Still more input */
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output_index < outputWidth /* Still more output to fill */)
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{
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MinorDynInstPtr inst = insts_in->insts[inputIndex];
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if (inst->isBubble()) {
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/* Skip */
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inputIndex++;
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inMacroop = false;
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} else {
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StaticInstPtr static_inst = inst->staticInst;
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/* Static inst of a macro-op above the output_inst */
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StaticInstPtr parent_static_inst = NULL;
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MinorDynInstPtr output_inst = inst;
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if (inst->isFault()) {
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DPRINTF(Decode, "Fault being passed: %d\n",
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inst->fault->name());
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inputIndex++;
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inMacroop = false;
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} else if (static_inst->isMacroop()) {
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/* Generate a new micro-op */
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StaticInstPtr static_micro_inst;
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/* Set up PC for the next micro-op emitted */
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if (!inMacroop) {
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microopPC = inst->pc;
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inMacroop = true;
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}
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/* Get the micro-op static instruction from the
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* static_inst. */
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static_micro_inst =
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static_inst->fetchMicroop(microopPC.microPC());
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output_inst = new MinorDynInst(inst->id);
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output_inst->pc = microopPC;
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output_inst->staticInst = static_micro_inst;
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output_inst->fault = NoFault;
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/* Allow a predicted next address only on the last
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* microop */
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if (static_micro_inst->isLastMicroop()) {
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output_inst->predictedTaken = inst->predictedTaken;
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output_inst->predictedTarget = inst->predictedTarget;
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}
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DPRINTF(Decode, "Microop decomposition inputIndex:"
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" %d output_index: %d lastMicroop: %s microopPC:"
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" %d.%d inst: %d\n",
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inputIndex, output_index,
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(static_micro_inst->isLastMicroop() ?
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"true" : "false"),
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microopPC.instAddr(), microopPC.microPC(),
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*output_inst);
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/* Acknowledge that the static_inst isn't mine, it's my
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* parent macro-op's */
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parent_static_inst = static_inst;
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static_micro_inst->advancePC(microopPC);
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/* Step input if this is the last micro-op */
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if (static_micro_inst->isLastMicroop()) {
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inputIndex++;
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inMacroop = false;
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}
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} else {
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/* Doesn't need decomposing, pass on instruction */
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DPRINTF(Decode, "Passing on inst: %s inputIndex:"
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" %d output_index: %d\n",
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*output_inst, inputIndex, output_index);
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parent_static_inst = static_inst;
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/* Step input */
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inputIndex++;
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inMacroop = false;
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}
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/* Set execSeqNum of output_inst */
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output_inst->id.execSeqNum = execSeqNum;
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/* Add tracing */
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#if TRACING_ON
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dynInstAddTracing(output_inst, parent_static_inst, cpu);
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#endif
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/* Step to next sequence number */
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execSeqNum++;
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/* Correctly size the output before writing */
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2016-02-07 02:21:19 +01:00
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if (output_index == 0) insts_out.resize(outputWidth);
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2014-07-23 23:09:04 +02:00
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/* Push into output */
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insts_out.insts[output_index] = output_inst;
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output_index++;
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}
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/* Have we finished with the input? */
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if (inputIndex == insts_in->width()) {
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/* If we have just been producing micro-ops, we *must* have
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* got to the end of that for inputIndex to be pushed past
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* insts_in->width() */
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assert(!inMacroop);
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popInput();
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insts_in = NULL;
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if (processMoreThanOneInput) {
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DPRINTF(Decode, "Wrapping\n");
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insts_in = getInput();
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}
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}
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}
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/* The rest of the output (if any) should already have been packed
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* with bubble instructions by insts_out's initialisation
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*
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* for (; output_index < outputWidth; output_index++)
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* assert(insts_out.insts[output_index]->isBubble());
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*/
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}
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/* If we generated output, reserve space for the result in the next stage
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* and mark the stage as being active this cycle */
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if (!insts_out.isBubble()) {
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/* Note activity of following buffer */
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cpu.activityRecorder->activity();
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nextStageReserve.reserve();
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}
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/* If we still have input to process and somewhere to put it,
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* mark stage as active */
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if (getInput() && nextStageReserve.canReserve())
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cpu.activityRecorder->activateStage(Pipeline::DecodeStageId);
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/* Make sure the input (if any left) is pushed */
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inputBuffer.pushTail();
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}
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bool
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Decode::isDrained()
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{
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return inputBuffer.empty() && (*inp.outputWire).isBubble();
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}
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void
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Decode::minorTrace() const
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{
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std::ostringstream data;
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if (blocked)
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data << 'B';
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else
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(*out.inputWire).reportData(data);
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MINORTRACE("insts=%s\n", data.str());
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inputBuffer.minorTrace();
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}
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}
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