stats: Add support for hierarchical stats

This change makes the stat system aware of the hierarchical nature of
stats. The aim is to achieve the following goals:

* Make the SimObject hierarchy explicit in the stat system (i.e.,
get rid of name() + ".foo"). This makes stat naming less fragile
and makes it possible to implement hierarchical formats like
XML/HDF5/JSON in a clean way.

* Make it more convenient to split stats into a separate
struct/class that can be bound to a SimObject. This makes the
namespace cleaner and makes stat accesses a bit more obvious.

* Make it possible to build groups of stats in C++ that can be used
in subcomponents in a SimObject (similar to what we do for
checkpoint sections). This makes it easier to structure large
components.

* Enable partial stat dumps. Some of our internal users have been
asking for this since a full stat dump can be large.

* Enable better stat access from Python.

This changeset implements solves the first three points by introducing
a class (Stats::Group) that owns statistics belonging to the same
object. SimObjects inherit from Stats::Group since they typically have
statistics.

New-style statistics need to be associated with a parent group at
instantiation time. Instantiation typically sets the name and the
description, other parameters need to be set by overriding
Group::regStats() just like with legacy stats. Simple objects with
scalar stats can typically avoid implementing regStats() altogether
since the stat name and description are both specified in the
constructor.

For convenience reasons, statistics groups can be merged into other
groups. This means that a SimObject can create a stat struct that
inherits from Stats::Group and merge it into the parent group
(SimObject). This can make the code cleaner since statistics tracking
gets grouped into a single object.

Stat visitors have a new API to expose the group structure. The
Output::beginGroup(name) method is called at the beginning of a group
and the Output::endGroup() method is called when all stats, and
sub-groups, have been visited. Flat formats (e.g., the text format)
typically need to maintain a stack to track the full path to a stat.

Legacy, flat, statistics are still supported after applying this
change. These stats don't belong to any group and stat visitors will
not see a Output::beginGroup(name) call before their corresponding
Output::visit() methods are called.

Change-Id: I9025d61dfadeabcc8ecf30813ab2060def455648
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19368
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>

sim: Add a getPort function to SimObject.

This will retrieve a Port object from a given SimObject (which might
not be a MemObject) no matter what flavor of Port it is.

Change-Id: I636b85e9d4929a05a769e165849106bcb5f3e9c1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17037
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

style: [patch 3/22] reduce include dependencies in some headers

Used cppclean to help identify useless includes and removed them. This
involved erroneously included headers, but also cases where forward
declarations could have been used rather than a full include.

misc: Remove redundant compiler-specific defines

This patch moves away from using M5_ATTR_OVERRIDE and the m5::hashmap
(and similar) abstractions, as these are no longer needed with gcc 4.7
and clang 3.1 as minimum compiler versions.

sim: Move SimObject resolver to sim_object.hh

The object resolver isn't serialization specific and shouldn't live in
serialize.hh. Move it to sim_object.hh since it queries to the
SimObject hierarchy.

sim: Refactor and simplify the drain API

The drain() call currently passes around a DrainManager pointer, which
is now completely pointless since there is only ever one global
DrainManager in the system. It also contains vestiges from the time
when SimObjects had to keep track of their child objects that needed
draining.

This changeset moves all of the DrainState handling to the Drainable
base class and changes the drain() and drainResume() calls to reflect
this. Particularly, the drain() call has been updated to take no
parameters (the DrainManager argument isn't needed) and return a
DrainState instead of an unsigned integer (there is no point returning
anything other than 0 or 1 any more). Drainable objects should return
either DrainState::Draining (equivalent to returning 1 in the old
system) if they need more time to drain or DrainState::Drained
(equivalent to returning 0 in the old system) if they are already in a
consistent state. Returning DrainState::Running is considered an
error.

Drain done signalling is now done through the signalDrainDone() method
in the Drainable class instead of using the DrainManager directly. The
new call checks if the state of the object is DrainState::Draining
before notifying the drain manager. This means that it is safe to call
signalDrainDone() without first checking if the simulator has
requested draining. The intention here is to reduce the code needed to
implement draining in simple objects.

sim: Move mem(Writeback|Invalidate) to SimObject

The memWriteback() and memInvalidate() calls used to live in the
Serializable interface. In this series of patches, the Serializable
interface will be redesigned to make serialization independent of the
object graph and always work on the entire simulator. This means that
the Serialization interface won't be useful to perform maintenance of
the caches in a sub-graph of the entire SimObject graph. This
changeset moves these memory maintenance methods to the SimObject
interface instead.

sim: Refactor the serialization base class

Objects that are can be serialized are supposed to inherit from the
Serializable class. This class is meant to provide a unified API for
such objects. However, so far it has mainly been used by SimObjects
due to some fundamental design limitations. This changeset redesigns
to the serialization interface to make it more generic and hide the
underlying checkpoint storage. Specifically:

* Add a set of APIs to serialize into a subsection of the current
object. Previously, objects that needed this functionality would
use ad-hoc solutions using nameOut() and section name
generation. In the new world, an object that implements the
interface has the methods serializeSection() and
unserializeSection() that serialize into a named /subsection/ of
the current object. Calling serialize() serializes an object into
the current section.

* Move the name() method from Serializable to SimObject as it is no
longer needed for serialization. The fully qualified section name
is generated by the main serialization code on the fly as objects
serialize sub-objects.

* Add a scoped ScopedCheckpointSection helper class. Some objects
need to serialize data structures, that are not deriving from
Serializable, into subsections. Previously, this was done using
nameOut() and manual section name generation. To simplify this,
this changeset introduces a ScopedCheckpointSection() helper
class. When this class is instantiated, it adds a new /subsection/
and subsequent serialization calls during the lifetime of this
helper class happen inside this section (or a subsection in case
of nested sections).

* The serialize() call is now const which prevents accidental state
manipulation during serialization. Objects that rely on modifying
state can use the serializeOld() call instead. The default
implementation simply calls serialize(). Note: The old-style calls
need to be explicitly called using the
serializeOld()/serializeSectionOld() style APIs. These are used by
default when serializing SimObjects.

* Both the input and output checkpoints now use their own named
types. This hides underlying checkpoint implementation from
objects that need checkpointing and makes it easier to change the
underlying checkpoint storage code.

misc: Fix issues identified by static analysis

Another bunch of issues addressed.

base: add support for probe points and common probes

The probe patch is motivated by the desire to move analytical and trace code
away from functional code. This is achieved by the probe interface which is
essentially a glorified observer model.

What this means to users:
* add a probe point and a "notify" call at the source of an "event"
* add an isolated module, that is being used to carry out *your* analysis (e.g. generate a trace)
* register that module as a probe listener
Note: an example is given for reference in src/cpu/o3/simple_trace.[hh|cc] and src/cpu/SimpleTrace.py

What is happening under the hood:
* every SimObject maintains has a ProbeManager.
* during initialization (src/python/m5/simulate.py) first regProbePoints and
the regProbeListeners is called on each SimObject. this hooks up the probe
point notify calls with the listeners.

FAQs:
Why did you develop probe points:
* to remove trace, stats gathering, analytical code out of the functional code.
* the belief that probes could be generically useful.

What is a probe point:
* a probe point is used to notify upon a given event (e.g. cpu commits an instruction)

What is a probe listener:
* a class that handles whatever the user wishes to do when they are notified
about an event.

What can be passed on notify:
* probe points are templates, and so the user can generate probes that pass any
type of argument (by const reference) to a listener.

What relationships can be generated (1:1, 1:N, N:M etc):
* there isn't a restriction. You can hook probe points and listeners up in a
1:1, 1:N, N:M relationship. They become useful when a number of modules
listen to the same probe points. The idea being that you can add a small
number of probes into the source code and develop a larger number of useful
analysis modules that use information passed by the probes.

Can you give examples:
* adding a probe point to the cpu's commit method allows you to build a trace
module (outputting assembler), you could re-use this to gather instruction
distribution (arithmetic, load/store, conditional, control flow) stats.

Why is the probe interface currently restricted to passing a const reference:
* the desire, initially at least, is to allow an interface to observe
functionality, but not to change functionality.
* of course this can be subverted by const-casting.

What is the performance impact of adding probes:
* when nothing is actively listening to the probes they should have a
relatively minor impact. Profiling has suggested even with a large number of
probes (60) the impact of them (when not active) is very minimal (<1%).

scons: Add warning for missing declarations

This patch enables warnings for missing declarations. To avoid issues
with SWIG-generated code, the warning is only applied to non-SWIG
code.

sim: have a curTick per eventq
This patch adds a _curTick variable to an eventq. This variable is updated
whenever an event is serviced in function serviceOne(), or all events upto
a particular time are processed in function serviceEvents(). This change
helps when there are eventqs that do not make use of curTick for scheduling
events.

sim: Move the draining interface into a separate base class

This patch moves the draining interface from SimObject to a separate
class that can be used by any object needing draining. However,
objects not visible to the Python code (i.e., objects not deriving
from SimObject) still depend on their parents informing them when to
drain. This patch also gets rid of the CountedDrainEvent (which isn't
really an event) and replaces it with a DrainManager.

sim: Move CPU-specific methods from SimObject to the BaseCPU class

sim: Remove SimObject::setMemoryMode

Remove SimObject::setMemoryMode from the main SimObject class since it
is only valid for the System class. In addition to removing the method
from the C++ sources, this patch also removes getMemoryMode and
changeTiming from SimObject.py and updates the simulation code to call
the (get|set)MemoryMode method on the System object instead.

sim: Update the SimObject documentation

Includes a small change in sim_object.cc that adds the name space to
the output stream parameter in serializeAll. Leaving out the name
space unfortunately confuses Doxygen.

sim: Remove the unused SimObject::regFormulas method

Simulation objects normally register derived statistics, presumably
what regFormulas originally was meant for, in regStats(). This patch
removes regRegformulas since there is no need to have a separate
method call to register formulas.

clang: Enable compiling gem5 using clang 2.9 and 3.0

This patch adds the necessary flags to the SConstruct and SConscript
files for compiling using clang 2.9 and later (on Ubuntu et al and OSX
XCode 4.2), and also cleans up a bunch of compiler warnings found by
clang. Most of the warnings are related to hidden virtual functions,
comparisons with unsigneds >= 0, and if-statements with empty
bodies. A number of mismatches between struct and class are also
fixed. clang 2.8 is not working as it has problems with class names
that occur in multiple namespaces (e.g. Statistics in
kernel_stats.hh).

clang has a bug (http://llvm.org/bugs/show_bug.cgi?id=7247) which
causes confusion between the container std::set and the function
Packet::set, and this is currently addressed by not including the
entire namespace std, but rather selecting e.g. "using std::vector" in
the appropriate places.

sim: add some DPRINTFs for debugging unserialization
Also got rid of unused C++ unserializeAll() method
(this is now handled in Python)

Replace curTick global variable with accessor functions.
This step makes it easy to replace the accessor functions
(which still access a global variable) with ones that access
per-thread curTick values.

misc: add some AMD copyright notices
Meant to add these with the previous batch of csets.

sim: revamp unserialization procedure

Replace direct call to unserialize() on each SimObject with a pair of
calls for better control over initialization in both ckpt and non-ckpt
cases.

If restoring from a checkpoint, loadState(ckpt) is called on each
SimObject. The default implementation simply calls unserialize() if
there is a corresponding checkpoint section, so we get backward
compatibility for existing objects. However, objects can override
loadState() to get other behaviors, e.g., doing other programmed
initializations after unserialize(), or complaining if no checkpoint
section is found. (Note that the default warning for a missing
checkpoint section is now gone.)

If not restoring from a checkpoint, we call the new initState() method
on each SimObject instead. This provides a hook for state
initializations that are only required when *not* restoring from a
checkpoint.

Given this new framework, do some cleanup of LiveProcess subclasses
and X86System, which were (in some cases) emulating initState()
behavior in startup via a local flag or (in other cases) erroneously
doing initializations in startup() that clobbered state loaded earlier
by unserialize().

sim: move iterating over SimObjects into Python.

sim: fold StartupCallback into SimObject
There used to be a reason to have StartupCallback
be a separate object, but not any more. Now
it's just confusing.

stats: get rid of the never-really-used event stuff

eventq: Major API change for the Event and EventQueue structures.

Since the early days of M5, an event needed to know which event queue
it was on, and that data was required at the time of construction of
the event object. In the future parallelized M5, this sort of
requirement does not work well since the proper event queue will not
always be known at the time of construction of an event. Now, events
are created, and the EventQueue itself has the schedule function,
e.g. eventq->schedule(event, when). To simplify the syntax, I created
a class called EventManager which holds a pointer to an EventQueue and
provides the schedule interface that is a proxy for the EventQueue.
The intent is that objects that frequently schedule events can be
derived from EventManager and then they have the schedule interface.
SimObject and Port are examples of objects that will become
EventManagers. The end result is that any SimObject can just call
schedule(event, when) and it will just call that SimObject's
eventq->schedule function. Of course, some objects may have more than
one EventQueue, so this interface might not be perfect for those, but
they should be relatively few.

params: Get rid of the remnants of the old style parameter configuration stuff.

SimObject: Add in missing includes of <string> and fix minor style problem.

Additional comments and helper functions for PrintReq.

Add functional PrintReq command for memory-system debugging.

params: Deprecate old-style constructors; update most SimObject constructors.

SimObjects not yet updated:
- Process and subclasses
- BaseCPU and subclasses

The SimObject(const std::string &name) constructor was removed. Subclasses
that still rely on that behavior must call the parent initializer as
: SimObject(makeParams(name))

Major changes to how SimObjects are created and initialized. Almost all
creation and initialization now happens in python. Parameter objects
are generated and initialized by python. The .ini file is now solely for
debugging purposes and is not used in construction of the objects in any
way.

Remove the event_ignore stuff since it was never really used

remove connectAll() and connect() code since it isn't used anymore. (The python does it all)

since memoryMode was put into the System (from SimObject), things got broken - this fixes it so that changeToTiming/changeToAtomic works.

src/python/m5/SimObject.py:
now that setMemoryMode is a method in System, need to convert the SimObject * _ccObject into a system ptr to call setMemoryMode.
src/sim/main.cc:
need this conversion now.
src/sim/sim_object.hh:
put the enum back into SimObject.
src/sim/system.hh:
memoryMode is now a part of SimObject, need the ::'s

memory mode information now contained in system object
States are now running, draining, or drained. memory state information moved into system object
system parameter is not fs only for cpus
Implement drain() support in devices
Update for drain() call that returns number of times drain_event->process() will be called

Break O3 CPU! No sense in putting in a hack change that kevin is going to remove in a few minutes i imagine

src/cpu/simple/atomic.cc:
src/cpu/simple/atomic.hh:
Since se mode has a system, allow access to it
Verify that the atomic cpu is connected to an atomic system on resume
src/cpu/simple/base.cc:
Since se mode has a system, allow access to it
src/cpu/simple/timing.cc:
src/cpu/simple/timing.hh:
Update for new drain() call that returns number of times drain_event->process() will be called and memory state being moved into the system
Since se mode has a system, allow access to it
Verify that the timing cpu is connected to an timing system on resume
src/dev/ide_disk.cc:
src/dev/io_device.cc:
src/dev/io_device.hh:
src/dev/ns_gige.cc:
src/dev/ns_gige.hh:
src/dev/pcidev.cc:
src/dev/pcidev.hh:
src/dev/sinic.cc:
src/dev/sinic.hh:
Implement drain() support in devices
src/python/m5/config.py:
Allow drain to return number of times drain_event->process() will be called. Normally 0 or 1 but things like O3 cpu or devices with multiple ports may want to call it many times
src/python/m5/objects/BaseCPU.py:
move system parameter out of fs to everyone
src/sim/sim_object.cc:
src/sim/sim_object.hh:
States are now running, draining, or drained. memory state information moved into system object
src/sim/system.cc:
src/sim/system.hh:
memory mode information now contained in system object

Change the return value of drain. False means the object wasn't able to drain yet.

src/python/m5/config.py:
Invert the return value.
src/sim/sim_object.cc:
Invert the return value of drain.
src/sim/sim_object.hh:
Change the return value of drain.

Rename quiesce to drain to avoid confusion with the pseudo instruction.

src/cpu/simple/timing.cc:
src/cpu/simple/timing.hh:
src/python/m5/__init__.py:
src/python/m5/config.py:
src/sim/main.cc:
src/sim/sim_events.cc:
src/sim/sim_events.hh:
src/sim/sim_object.cc:
src/sim/sim_object.hh:
Rename quiesce to drain.

Add in support for quiescing the system, taking checkpoints, restoring from checkpoints, changing memory modes, and switching CPUs.

Key new functions that can be called on the m5 object at the python interpreter:
doQuiesce(root) - A helper function that quiesces the object passed in and all of its children.
resume(root) - Another helper function that tells the object and all of its children that the quiesce is over.
checkpoint(root) - Takes a checkpoint of the system. Checkpoint directory must be set before hand.
setCheckpointDir(name) - Sets the checkpoint directory.
restoreCheckpoint(root) - Restores the values from the checkpoint located in the checkpoint directory.
changeToAtomic(system) - Changes the system and all of its children to atomic memory mode.
changeToTiming(system) - Changes the system and all of its children to timing memory mode.
switchCpus(list) - Takes in a list of tuples, where each tuple is a pair of (old CPU, new CPU). Quiesces the old CPUs, and then switches over to the new CPUs.

src/SConscript:
Remove serializer, replaced by python code.
src/python/m5/__init__.py:
Updates to support quiescing, checkpointing, changing memory modes, and switching CPUs.
src/python/m5/config.py:
Several functions defined on the SimObject for quiescing, changing timing modes, and switching CPUs
src/sim/main.cc:
Add some extra functions that are exported to python through SWIG.
src/sim/serialize.cc:
Change serialization around a bit. Now it is controlled through Python, so there's no need for SerializeEvents or SerializeParams.

Also add in a new unserializeAll() function that loads a checkpoint and handles unserializing all objects.
src/sim/serialize.hh:
Add unserializeAll function and a setCheckpointName function.
src/sim/sim_events.cc:
Add process() function for CountedQuiesceEvent, which calls exitSimLoop() once its counter reaches 0.
src/sim/sim_events.hh:
Add in a CountedQuiesceEvent, which is used when the system is preparing to quiesce. Any objects that can't be quiesced immediately are given a pointer to a CountedQuiesceEvent. The event has its counter set via Python, and as objects finish quiescing they call process() on the event. Eventually the event causes the simulation to stop once all objects have quiesced.
src/sim/sim_object.cc:
Add a few functions for quiescing, checkpointing, and changing memory modes.
src/sim/sim_object.hh:
Add a state variable to all SimObjects that tracks both the timing mode of the object and the quiesce state of the object. Currently this isn't serialized, and I'm not sure it needs to be so long as the timing mode starts up the same after a checkpoint.

Updated Authors from bk prs info

New directory structure:
- simulator source now in 'src' subdirectory
- imported files from 'ext' repository
- support building in arbitrary places, including
outside of the source tree. See comment at top
of SConstruct file for more details.
Regression tests are temporarily disabled; that
syetem needs more extensive revisions.

SConstruct:
Update for new directory structure.
Modify to support build trees that are not subdirectories
of the source tree. See comment at top of file for
more details.
Regression tests are temporarily disabled.
src/arch/SConscript:
src/arch/isa_parser.py:
src/python/SConscript:
Update for new directory structure.