Adds timing support to Verilator. It makes it possible to use delays,
event controls within processes (not just at the start), wait
statements, and forks.
Building a design with those constructs requires a compiler that
supports C++20 coroutines (GCC 10, Clang 5).
The basic idea is to have processes and tasks with delays/event controls
implemented as C++20 coroutines. This allows us to suspend and resume
them at any time.
There are five main runtime classes responsible for managing suspended
coroutines:
* `VlCoroutineHandle`, a wrapper over C++20's `std::coroutine_handle`
with move semantics and automatic cleanup.
* `VlDelayScheduler`, for coroutines suspended by delays. It resumes
them at a proper simulation time.
* `VlTriggerScheduler`, for coroutines suspended by event controls. It
resumes them if its corresponding trigger was set.
* `VlForkSync`, used for syncing `fork..join` and `fork..join_any`
blocks.
* `VlCoroutine`, the return type of all verilated coroutines. It allows
for suspending a stack of coroutines (normally, C++ coroutines are
stackless).
There is a new visitor in `V3Timing.cpp` which:
* scales delays according to the timescale,
* simplifies intra-assignment timing controls and net delays into
regular timing controls and assignments,
* simplifies wait statements into loops with event controls,
* marks processes and tasks with timing controls in them as
suspendable,
* creates delay, trigger scheduler, and fork sync variables,
* transforms timing controls and fork joins into C++ awaits
There are new functions in `V3SchedTiming.cpp` (used by `V3Sched.cpp`)
that integrate static scheduling with timing. This involves providing
external domains for variables, so that the necessary combinational
logic gets triggered after coroutine resumption, as well as statements
that need to be injected into the design eval function to perform this
resumption at the correct time.
There is also a function that transforms forked processes into separate
functions.
See the comments in `verilated_timing.h`, `verilated_timing.cpp`,
`V3Timing.cpp`, and `V3SchedTiming.cpp`, as well as the internals
documentation for more details.
Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>
Tests used to silently pass when vcddiff aborted. Now fixed. Updated
large array trace reference files for FST, added same reference files
for VCD.
Developers need to update their local vcddiff.
Prep for adding more CI targets. Building dbg and opt in the same job
(as standard) simplifies caching, debugging and artifact handling. With
ccache it should not take much longer either. Also removes the need to
re-configure in the test job.
* Add the initial version of CI using GitHub Actions
* Update .github/workflows/check_pr.yml
Co-authored-by: Wilson Snyder <wsnyder@wsnyder.org>
* remove setting for travis
* rename travis-*.bash to ci-*.bash
* Rename TRAVIS_ variables to CI_
* install ccache and libsystemc(-dev) in ci-install.bash
* Use CI_ variables and Ubuntu-20.04 that provides SystemC
* call ccache maintenance
Co-authored-by: Wilson Snyder <wsnyder@wsnyder.org>
Change the Travis builds to use workspaces and persistent ccache
We proceed in 2 stages (as before, but using workspaces for
persistence):
1. In the 'build' stage, we clone the repo, build it and
save the whole checkout ($TRAVIS_BUILD_DIR) as a workspace
2. In the 'test' stage, rather than cloning the repo, multiple jobs
pull down the same workspace we built to run the tests from
This enables:
- Reuse of the build in multiple test jobs (this is what we used the Travis
cache for before)
- Each job having a separate persistent Travis cache, which now only
contains the ccache. This means all jobs, including 'build' and 'test'
jobs can make maximum use of ccache across runs. This drastically cuts
down build times when the ccache hits, which is very often the case for
'test' jobs. Also, the separate caches only store the objects build by
the particular job that owns the cache, so we can keep the per job
ccache small.
If the commit message contains '[travis ccache clear]', the ccache will
be cleared at the beginning of the build. This can be used to test build
complete within the 50 minute timeout imposed by Travis, even without a
persistent ccache.
Unify the actions in the Dockerfiles between the runtime environment
and the run containers.
Fixes#2345
Signed-off-by: Stefan Wallentowitz <stefan.wallentowitz@hm.edu>
