systemc: Handle exceptions "correctly" even if sc_main hasn't been run.

If sc_main hasn't run, for instance if there isn't an sc_main and gem5
is orchestrating the simulation directly, then exceptions shouldn't be
thrown to the sc_main fiber since it isn't running and may not be able
to run since sc_main may not even exist.

Instead, we need to check whether it makes sense to throw to sc_main,
and if not pass the exception directly to the report handler since
there likely won't be anyone to catch it if we just throw it from the
scheduler or into general purpose gem5.

Since the name throwToScMain is no longer a complete description for
what that function does, this change renames it to throwUp, since it
will now throw exceptions up the stack, either to sc_main or to the
conceptual top level by going directly to the report handler.

Change-Id: Ibdc92c9cf213ec6aa15ad654862057b7bf2e1c8e
Reviewed-on: https://gem5-review.googlesource.com/c/16442
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Seperate out the sc_main fiber and its bookkeeping.

By pulling out the sc_main fiber (scMainFiber), we can make it
available to different entities in the simulator and avoid having to
have parallel bookkeeping.

Also this will make it possible to hook into sc_main without putting
the code in sc_main.cc.

Change-Id: I7689441424238e9b2e4d2b48e945dea35fd8cc5d
Reviewed-on: https://gem5-review.googlesource.com/c/13977
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Change the point where elaboration is considered over.

Make it the end of "before_end_of_elaboration" rather than the end
of "end_of_elaboration". This interpretation fits the behavior expected
by some of the tests.

Change-Id: I3f589147834ab5d5dc8c0e9b4849dd00491c5848
Reviewed-on: https://gem5-review.googlesource.com/c/13287
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Add missing sc_interface::register_port, and add calls to it.

This function is standard and supposed to be on sc_interface, but it
was somehow left out. This change adds it, and makes sure it's called
by the port binding code. The default implementation does nothing, as
it's supposed to according to the spec.

Also note that only the ports farthest from the interfaces are suppose
to call register_port. As the port bindings are completed, we keep
track of whether a port has been bound to another port. If it has, the
source port is farther from the interfaces than the target port (since
it has to go "through" the target port to get to them, and so the
target port should not call register_port.

Change-Id: Ia98f9ff364385fd1699d88a1d99787d205816a08
Reviewed-on: https://gem5-review.googlesource.com/c/13199
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Rework how delayed sensitivities are handled.

Make BindInfo into a more general purpose Port class which mirrors
sc_module and Module, sc_object and Object, etc. This tracks multiple
bindings internally, and also pending sensitivities. Keep a global
list of ports which are added in reverse order to match Accellera, and
which is iterated over to finalize binding and for phase callbacks.
This is as opposed to doing it one module at a time, and is to better
match Accellera's ordering for the regressions.

Also the sensitivity classes are now built with factory functions,
which gets around problems calling virtual functions from their
constructors or forgetting to having to have extra boilerplate each
place they're constructed.

The port class also now finalizes port or event finder sensitivities
when its binding is completed, unless it's already complete in which
case it does so immediately.

Change-Id: I1b01689715c425b94e0f68cf0271f5c1565d8c61
Reviewed-on: https://gem5-review.googlesource.com/c/12806
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Centralize module callbacks and report new warnings.

By centralizing module callbacks, the gem5 module class knows when
different stages of the simulation are happening and can do it's own
extra checks. It also compartmentalizes modules more since the kernel
object doesn't have to reach into them to enumerate ports and exports.

Change-Id: I55887284af9c05150fe9d054f5b6147cad6092a1
Reviewed-on: https://gem5-review.googlesource.com/c/12610
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Catch exceptions during updates, notifications, and callbacks.

Change-Id: I6005c12ce32d24413618e3955625432985f99f69
Reviewed-on: https://gem5-review.googlesource.com/c/12607
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Remove a redundant call to update() from the kernel object.

The t0Handler runs the scheduler's initPhase function which has a call
to update built into it. There's no reason to call that within one of
the kernel's callbacks as well.

Change-Id: I02c755b7d53f93accdacf8149cc1988d7a6e214c
Reviewed-on: https://gem5-review.googlesource.com/c/12604
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Ensure sc_stop during callbacks actually stops.

Make sure calling sc_stop during the appropriate callbacks will
actually skip future action by skipping later callbacks, by flushing
the scheduler before running init (so it doesn't really do anything
but record that it's in running mode now), and schedule the stop event.

Change-Id: I5edfbceda457df88d15bfcac4d97e8578205ec5b
Reviewed-on: https://gem5-review.googlesource.com/c/12468
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Track the module who's end_of_elaboration callback we're in.

Change-Id: Ib5fe3232cfea26df0c3396c583fd80da429cbdd5
Reviewed-on: https://gem5-review.googlesource.com/c/12442
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Fix where we checked if sc_stop was called durig elaboration.

If sc_stop is called during one of the various callbacks, that has
defined behavior and will cause the simulation to stop after the
current batch of callbacks. We were checking whether sc_stop had been
called during one of those batches and killing the system, erroneously
assuming that meant it had called during elaboration.

This change moves the check to before the callbacks which actually
does mean that sc_stop was called during elaboration.

Change-Id: I6876305450e52a407acffb9a2f45ee2ae24a9adf
Reviewed-on: https://gem5-review.googlesource.com/12266
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: If sc_main returns, don't do any more systemc stuff.

When sc_main returns, clear out any pending work in the scheduler and
also block the systemc kernel from doing actions which correspond with
the start of simulation.

It's most likely that work like oustanding timeouts might survive past
the end of sc_main, especially if it never officially called sc_stop.
It's also possible for sc_main to return and never actually call
sc_start. In that case, the kernel should not call callbacks of the
various objects (which may no longer even exist), or go through the
initialization phase.

If sc_main is never called at all, then the kernel's actions aren't
gated.

Change-Id: I49bf094be3283a92d846d2f3da224950bd893a5c
Reviewed-on: https://gem5-review.googlesource.com/12249
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Rework the init phase for the new way delta notes are handled.

The initialization phase had been done in a somewhat adhoc way,
partially because delta notifications were being handled as top level
gem5 events which were ordered based on their priorities. This change
makes the initialization phase happen more explicitly, and more in the
order in the spec.

Change-Id: I91d56b63fefcb81c845c52c97826a976a7559fad
Reviewed-on: https://gem5-review.googlesource.com/12217
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Track exports and prim channels, and call their callbacks.

Also call the callbacks on the ports which were already being tracked.

Change-Id: I5ba8ea366e87fc48b58712f35b93c27bccf92cb3
Reviewed-on: https://gem5-review.googlesource.com/12210
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Implement port binding except positional binding.

This change adds code which keeps track of ports and interfaces which
are being bound to be finalized later, and the actual port binding of
interfaces and recursive binding port ports.

Change-Id: Ifa885ed44b667254762cc101580be4f0a7d7a131
Reviewed-on: https://gem5-review.googlesource.com/12084
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Track the module in the end_of_elaboration callback.

sc_objects constructed during that callback are considered children of
the module the callback belongs to.

Change-Id: I164863a10beef6d0e2c6d9c5e8f2642d80769dca
Reviewed-on: https://gem5-review.googlesource.com/12076
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Set the scheduler's event queue earlier.

The kernel can set the event queue during its own construction which
will ensure that the scheduler can schedule events as early as
possible.

Change-Id: I0e47ca0a667e77d36c97860cd7c6b7577415c801
Reviewed-on: https://gem5-review.googlesource.com/12073
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Make some functions of the kernel static.

This makes it possible to call them without having to have a kernel
instance available. The kernel is a singleton anyway, so there should
only ever be a single instance of any of these values.

Change-Id: I3610d60cc72e9f3114997fe63db94b96ccaac3cd
Reviewed-on: https://gem5-review.googlesource.com/12041
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Implement the various sc_module stage callbacks.

This change also gets rid of the SystemC namespace which was
deprecated in favor of sc_gem5.

A few utility functions which check whether certain callbacks have
finished were also implemented. status tracking moved from a global
variable in sc_main.cc to a member of the kernel simobject.

Change-Id: I50967fae9c576fbe45b1faff587aaa824857a289
Reviewed-on: https://gem5-review.googlesource.com/12033
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Implement the sensitivity mechanism.

This change lets processes be sensitive to events, timeouts, etc.

Change-Id: If30a256dfa8a2e92192c1f9c96b48e2aa28ec27e
Reviewed-on: https://gem5-review.googlesource.com/11713
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Implement channel updates and rework the scheduler.

This change implements channel updates, and also reworks the scheduler
to delegate more to the gem5 event queue by taking advantage of
event priorities to ensure things happen in the right order. There's
a lengthy comment in scheduler.hh describes how that all works.

Change-Id: I5dee71b86b2e612bb720a4429f3a72e4b7c6d01f
Reviewed-on: https://gem5-review.googlesource.com/11710
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Partially implement the scheduler.

This change implements the "evaluate" part of the delta cycles, and
sketches out a function to run delta cycles and the initialization
phase. The kernel object now schedules an event at time zero which
runs the initialization phase.

Also, some small places which were stubbed out pending a way to check
the currently running process have been filled in now that that's
being tracked.

Change-Id: I6899569eb0195ff1c059fa4e68e90ef162b2f2df
Reviewed-on: https://gem5-review.googlesource.com/11709
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Seperate the "external" header interface.

Most (but not all) of the SystemC headers are part of the "external"
interface that an existing, standard compliant module would include
through <systemc.h> or <systemc>. Since those follow slightly different
rules (relative includes, no gem5 includes), this change separates them
out so that they're easier to identify.

Also, this change moves the other files into a "core" subdirectory,
with the intention to add a "dt", aka data type, directory some time in
the future when those standard defined types are implemented.

Change-Id: Ida63f9cc0bc0431024d4dd691cc5b22b944a99a8
Reviewed-on: https://gem5-review.googlesource.com/10835
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>