In vvp, the __vpiSignal object holds a pointer to the scope containing
the signal. This was getting set to the current scope when the net was
finally resolved, rather than to the scope where the net was declared.
If a thread becomes detached due to a join_any statement, that
thread must not attempt to join its parent, even if the parent
is waiting on a subsequent join statement.
Normally there is at most one signal attached to a vvp functor, but
due to port collapsing, there can be more than one. If these signals
are array words, we need to trigger vpi callbacks on all the associated
arrays when the functor value changes.
Change cbReadWriteSynch and cbReadOnlySynch to interpret the passed
time value as a relative delay, not an absolute time. This matches
the behaviour of other simulators.
SystemVerilog allows tasks, functions, and classes to be defined at the
root level or inside packages, so we can't rely on an enclosing module
being present to provide the timescale.
SystemVerilog allows a mixture of procedural and continuous assignments
to be applied to different parts of the same vector. The previous attempt
to make this work for non-blocking assignments was flawed (see preceding
fix for vvp_fun_part_pv::recv_vec4_pv). Instead, handle this case by
converting the non-blocking assignment into a delayed force statement,
which matches the way mixed continuous and blocking assignments are
handled.
Most vvp functors need to support recv_vec4_pv. Any that are strength-aware
also need to support recv_vec8_pv. Note the simplifying assumption that is
documented in the base class recv_vec4_pv_ implementation.
Flip-flops are generally modelled in behavioural code using non-blocking
assignments. This change makes the synthesised code behave the same as
the behavioural code. It's a more realistic model of a real flip-flop
too, which will always have some clock-to-output delay.
The .scope needs to be aware of return types so that the %call/vec4
function knows how to intialize the return value. We also need to
extend the %ret/vec4 to support writing parts of the return value.