cpu: `Minor' in-order CPU model

This patch contains a new CPU model named `Minor'. Minor models a four
stage in-order execution pipeline (fetch lines, decompose into
macroops, decompose macroops into microops, execute).

The model was developed to support the ARM ISA but should be fixable
to support all the remaining gem5 ISAs. It currently also works for
Alpha, and regressions are included for ARM and Alpha (including Linux
boot).

Documentation for the model can be found in src/doc/inside-minor.doxygen and
its internal operations can be visualised using the Minorview tool
utils/minorview.py.

Minor was designed to be fairly simple and not to engage in a lot of
instruction annotation. As such, it currently has very few gathered
stats and may lack other gem5 features.

Minor is faster than the o3 model. Sample results:

     Benchmark     |   Stat host_seconds (s)
    ---------------+--------v--------v--------
     (on ARM, opt) | simple | o3     | minor
                   | timing | timing | timing
    ---------------+--------+--------+--------
    10.linux-boot  |   169  |  1883  |  1075
    10.mcf         |   117  |   967  |   491
    20.parser      |   668  |  6315  |  3146
    30.eon         |   542  |  3413  |  2414
    40.perlbmk     |  2339  | 20905  | 11532
    50.vortex      |   122  |  1094  |   588
    60.bzip2       |  2045  | 18061  |  9662
    70.twolf       |   207  |  2736  |  1036

1 files changed, 362 insertions, 0 deletions

diff --git a/src/cpu/minor/cpu.cc b/src/cpu/minor/cpu.cc
new file mode 100644
index 000000000..f7007f6ff
--- /dev/null
+++ b/src/cpu/minor/cpu.cc
@@ -0,0 +1,362 @@
+/*
+ * Copyright (c) 2012-2014 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * 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;
+ * neither the name of the copyright holders 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
+ * OWNER 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: Andrew Bardsley
+ */
+
+#include "arch/utility.hh"
+#include "cpu/minor/cpu.hh"
+#include "cpu/minor/dyn_inst.hh"
+#include "cpu/minor/fetch1.hh"
+#include "cpu/minor/pipeline.hh"
+#include "debug/Drain.hh"
+#include "debug/MinorCPU.hh"
+#include "debug/Quiesce.hh"
+
+MinorCPU::MinorCPU(MinorCPUParams *params) :
+    BaseCPU(params),
+    drainManager(NULL)
+{
+    /* This is only written for one thread at the moment */
+    Minor::MinorThread *thread;
+
+    if (FullSystem) {
+        thread = new Minor::MinorThread(this, 0, params->system, params->itb,
+            params->dtb, params->isa[0]);
+    } else {
+        /* thread_id 0 */
+        thread = new Minor::MinorThread(this, 0, params->system,
+            params->workload[0], params->itb, params->dtb, params->isa[0]);
+    }
+
+    threads.push_back(thread);
+    threadActivateEvents.push_back(new ThreadActivateEvent(*this, 0));
+
+    thread->setStatus(ThreadContext::Halted);
+
+    ThreadContext *tc = thread->getTC();
+
+    if (params->checker) {
+        fatal("The Minor model doesn't support checking (yet)\n");
+    }
+
+    threadContexts.push_back(tc);
+
+    Minor::MinorDynInst::init();
+
+    pipeline = new Minor::Pipeline(*this, *params);
+    activityRecorder = pipeline->getActivityRecorder();
+}
+
+MinorCPU::~MinorCPU()
+{
+    delete pipeline;
+
+    for (ThreadID thread_id = 0; thread_id < threads.size(); thread_id++) {
+        delete threads[thread_id];
+        delete threadActivateEvents[thread_id];
+    }
+}
+
+void
+MinorCPU::init()
+{
+    BaseCPU::init();
+
+    if (!params()->switched_out &&
+        system->getMemoryMode() != Enums::timing)
+    {
+        fatal("The Minor CPU requires the memory system to be in "
+            "'timing' mode.\n");
+    }
+
+    /* Initialise the ThreadContext's memory proxies */
+    for (ThreadID thread_id = 0; thread_id < threads.size(); thread_id++) {
+        ThreadContext *tc = getContext(thread_id);
+
+        tc->initMemProxies(tc);
+    }
+
+    /* Initialise CPUs (== threads in the ISA) */
+    if (FullSystem && !params()->switched_out) {
+        for (ThreadID thread_id = 0; thread_id < threads.size(); thread_id++)
+        {
+            ThreadContext *tc = getContext(thread_id);
+
+            /* Initialize CPU, including PC */
+            TheISA::initCPU(tc, cpuId());
+        }
+    }
+}
+
+/** Stats interface from SimObject (by way of BaseCPU) */
+void
+MinorCPU::regStats()
+{
+    BaseCPU::regStats();
+    stats.regStats(name(), *this);
+    pipeline->regStats();
+}
+
+void
+MinorCPU::serializeThread(std::ostream &os, ThreadID thread_id)
+{
+    threads[thread_id]->serialize(os);
+}
+
+void
+MinorCPU::unserializeThread(Checkpoint *cp, const std::string &section,
+    ThreadID thread_id)
+{
+    if (thread_id != 0)
+        fatal("Trying to load more than one thread into a MinorCPU\n");
+
+    threads[thread_id]->unserialize(cp, section);
+}
+
+void
+MinorCPU::serialize(std::ostream &os)
+{
+    pipeline->serialize(os);
+    BaseCPU::serialize(os);
+}
+
+void
+MinorCPU::unserialize(Checkpoint *cp, const std::string &section)
+{
+    pipeline->unserialize(cp, section);
+    BaseCPU::unserialize(cp, section);
+}
+
+Addr
+MinorCPU::dbg_vtophys(Addr addr)
+{
+    /* Note that this gives you the translation for thread 0 */
+    panic("No implementation for vtophy\n");
+
+    return 0;
+}
+
+void
+MinorCPU::wakeup()
+{
+    DPRINTF(Drain, "MinorCPU wakeup\n");
+
+    for (auto i = threads.begin(); i != threads.end(); i ++) {
+        if ((*i)->status() == ThreadContext::Suspended)
+            (*i)->activate();
+    }
+
+    DPRINTF(Drain,"Suspended Processor awoke\n");
+}
+
+void
+MinorCPU::startup()
+{
+    DPRINTF(MinorCPU, "MinorCPU startup\n");
+
+    BaseCPU::startup();
+
+    for (auto i = threads.begin(); i != threads.end(); i ++)
+        (*i)->startup();
+}
+
+unsigned int
+MinorCPU::drain(DrainManager *drain_manager)
+{
+    DPRINTF(Drain, "MinorCPU drain\n");
+
+    drainManager = drain_manager;
+
+    /* Need to suspend all threads and wait for Execute to idle.
+     * Tell Fetch1 not to fetch */
+    unsigned int ret = pipeline->drain(drain_manager);
+
+    if (ret == 0)
+        DPRINTF(Drain, "MinorCPU drained\n");
+    else
+        DPRINTF(Drain, "MinorCPU not finished draining\n");
+
+    return ret;
+}
+
+void
+MinorCPU::signalDrainDone()
+{
+    DPRINTF(Drain, "MinorCPU drain done\n");
+    setDrainState(Drainable::Drained);
+    drainManager->signalDrainDone();
+    drainManager = NULL;
+}
+
+void
+MinorCPU::drainResume()
+{
+    assert(getDrainState() == Drainable::Drained ||
+        getDrainState() == Drainable::Running);
+
+    if (switchedOut()) {
+        DPRINTF(Drain, "drainResume while switched out.  Ignoring\n");
+        return;
+    }
+
+    DPRINTF(Drain, "MinorCPU drainResume\n");
+
+    if (!system->isTimingMode()) {
+        fatal("The Minor CPU requires the memory system to be in "
+            "'timing' mode.\n");
+    }
+
+    wakeup();
+    pipeline->drainResume();
+
+    setDrainState(Drainable::Running);
+}
+
+void
+MinorCPU::memWriteback()
+{
+    DPRINTF(Drain, "MinorCPU memWriteback\n");
+}
+
+void
+MinorCPU::switchOut()
+{
+    DPRINTF(MinorCPU, "MinorCPU switchOut\n");
+
+    assert(!switchedOut());
+    BaseCPU::switchOut();
+
+    /* Check that the CPU is drained? */
+    activityRecorder->reset();
+}
+
+void
+MinorCPU::takeOverFrom(BaseCPU *old_cpu)
+{
+    DPRINTF(MinorCPU, "MinorCPU takeOverFrom\n");
+
+    BaseCPU::takeOverFrom(old_cpu);
+
+    /* Don't think I need to do anything here */
+}
+
+void
+MinorCPU::activateContext(ThreadID thread_id, Cycles delay)
+{
+    DPRINTF(MinorCPU, "ActivateContext thread: %d delay: %d\n",
+        thread_id, delay);
+
+    if (!threadActivateEvents[thread_id]->scheduled()) {
+        schedule(threadActivateEvents[thread_id], clockEdge(delay));
+    }
+}
+
+void
+MinorCPU::ThreadActivateEvent::process()
+{
+    DPRINTFS(MinorCPU, (&cpu), "Activating thread: %d\n", thread_id);
+
+    /* Do some cycle accounting.  lastStopped is reset to stop the
+     *  wakeup call on the pipeline from adding the quiesce period
+     *  to BaseCPU::numCycles */
+    cpu.stats.quiesceCycles += cpu.pipeline->cyclesSinceLastStopped();
+    cpu.pipeline->resetLastStopped();
+
+    /* Wake up the thread, wakeup the pipeline tick */
+    cpu.threads[thread_id]->activate();
+    cpu.wakeupOnEvent(Minor::Pipeline::CPUStageId);
+    cpu.pipeline->wakeupFetch();
+}
+
+void
+MinorCPU::suspendContext(ThreadID thread_id)
+{
+    DPRINTF(MinorCPU, "SuspendContext %d\n", thread_id);
+
+    threads[thread_id]->suspend();
+}
+
+void
+MinorCPU::wakeupOnEvent(unsigned int stage_id)
+{
+    DPRINTF(Quiesce, "Event wakeup from stage %d\n", stage_id);
+
+    /* Mark that some activity has taken place and start the pipeline */
+    activityRecorder->activateStage(stage_id);
+    pipeline->start();
+}
+
+MinorCPU *
+MinorCPUParams::create()
+{
+    numThreads = 1;
+    if (!FullSystem && workload.size() != 1)
+        panic("only one workload allowed");
+    return new MinorCPU(this);
+}
+
+MasterPort &MinorCPU::getInstPort()
+{
+    return pipeline->getInstPort();
+}
+
+MasterPort &MinorCPU::getDataPort()
+{
+    return pipeline->getDataPort();
+}
+
+Counter
+MinorCPU::totalInsts() const
+{
+    Counter ret = 0;
+
+    for (auto i = threads.begin(); i != threads.end(); i ++)
+        ret += (*i)->numInst;
+
+    return ret;
+}
+
+Counter
+MinorCPU::totalOps() const
+{
+    Counter ret = 0;
+
+    for (auto i = threads.begin(); i != threads.end(); i ++)
+        ret += (*i)->numOp;
+
+    return ret;
+}