systemc: Ensure resets and edges are notified when signaling a change.

Boolean sc_buffers (either pure bool or sc_dt::sc_logic) should signal
positive and negative edges and resets even when their value doesn't
change, unlike sc_signals. The spec doesn't actually say that and just
mentions the value changed event, but it may have been implied that the
other types of events also happen, they just made special mention of
the value change event.

This change moves some code around a bit so that when _signalChange()
is called, if the underlying type is a boolean signal, it will
automatically notify the appropriate edge event and signal any reset.
Putting the functionality in _signalChange instead of delegating it to
the sc_buffer lets us have a single template for sc_buffer and makes
the base class template specialization handle whether the edge events
exist, and if so which should be notified.

Change-Id: Ic4ca86afc3fde6a9df5c15a0a7386e24ac89a9e2
Reviewed-on: https://gem5-review.googlesource.com/c/14916
Reviewed-by: Matthias Jung <jungma@eit.uni-kl.de>
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Switch to using predefined messages for channels.

Create and use predefined messages for channels which match the ones
Accellera uses.

Change-Id: I179214838bbd83604e50225926cdc6b5b1b16923
Reviewed-on: https://gem5-review.googlesource.com/c/13330
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Change how signal based resets work.

The previous implementation used the value changed event to track when
signals changed value, but there were a couple problems with this
approach. First, this piggybacked on the sensitivity mechanism in some
ways, but diverged in others. The sensitivity didn't notify a process
when it was satisfied like other sensitivity types would, and it also
ignored whether the process was disabled.

Second, the value_changed_event is notified by a signal instance as a
delta notification, but reset signals are supposed to act immediately.
That means they should happen before all delta notifications, or in
other words all delta notifications should see the reset status of a
given process. That's particularly important in the case of wait(int n)
where setting the reset clears the reset count, and the count is
checked when determining whether or not to wake up a process when its
sensitivity is satisfied, potentially by a delta notification.

Third, by removing the middle man and not trying to repurpose the
sensitivity mechanism, the code gets simpler and easier to understand.

Change-Id: I0d05d11437291d368b060f6a45a207813615f113
Reviewed-on: https://gem5-review.googlesource.com/c/13294
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Fix a typo in one of the error messages.

This typo was added purposefully to match Accellera's output, but then
it was discovered that some test's golden output had the typo, and some
didn't. That must mean that not all tests have up to date output, and
that Accellera couldn't possibly pass all of their own tests.

To resolve this conflict, this change fixes the typo and manually
updates all the golden output.

Change-Id: I3d80f74ff21e844609e7bde5dfcd99fc56c085b0
Reviewed-on: https://gem5-review.googlesource.com/c/13204
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

systemc: Implement writer policies.

This includes the nonstandard SC_NO_WRITE_CHECK #define which the
Accellera tests use and depend on.

Change-Id: I106c4c16160325725a00d5c337047251817dca32
Reviewed-on: https://gem5-review.googlesource.com/c/13203
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>