Multiple edge timing controls in class methods would cause compilation errors on
the generated C++ code. This is because the `SenExprBuilder` used for these
would get recreated per timing control, resulting in duplicate variable names.
The fix is to have a single `SenExprBuilder` per scope.
Multiple edge timing controls in class methods would cause compilation errors on the generated C++ code. This is because the `SenExprBuilder` used for these would get recreated per timing control, resulting in duplicate variable names. The fix is to have a single `SenExprBuilder` per scope.
Given nested forks, if the inner fork had a `join` or `join_any` at the end,
`V3Sched::transformForks()` would decide that the fork's `VlForkSync` variable
should be passed in from the outside. This resulted in the `VlForkSync` getting
redeclared as a function argument. Ultimately, it led to C++ compilation errors
due to variable redeclaration.
Fixed by rearranging the `if`s that decide whether a variable should be passed
in or left as-is.
This patch fixes two cases where methods in base classes were not being marked
as coroutines, even though they were being overridden by coroutines.
- One case is the class member cache not getting refreshed for searched classes.
- The other is when the overriding methods are not declared as `virtual`. In
that case, the `isVirtual()` getter on such a method returns false, which led
to `V3Timing` skipping the step of searching for overridden methods.
Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>
In non-static contexts like class objects or stack frames, the use of
global trigger evaluation is not feasible. The concept of dynamic
triggers allows for trigger evaluation in such cases. These triggers are
simply local variables, and coroutines are themselves responsible for
evaluating them. They await the global dynamic trigger scheduler object,
which is responsible for resuming them during the trigger evaluation
step in the 'act' eval region. Once the trigger is set, they await the
dynamic trigger scheduler once again, and then get resumed during the
resumption step in the 'act' eval region.
Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>
This change introduces a custom reference-counting pointer class that
allows creating such pointers from 'this'. This lets us keep the
receiver object around even if all references to it outside of a class
method no longer exist. Useful for coroutine methods, which may outlive
all external references to the object.
The deletion of objects is deferred until the next time slot. This is to
make clearing the triggered flag on named events in classes safe
(otherwise freed memory could be accessed).
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>
Krzysztof Bieganski
Wilson Snyder