Disable MULTIDRIVENPROC for static variables used as loop induction
variables. Same way as we disable similar warning in Dfg. While bad
style and bad for performance, it's common legacy code style.
The loops modelling the SystemVerilog scheduling regions are no longer
generated. They now live in 'VerilatedEvalLoop' in the runtime library.
The generated model holds one as a member, passing itself to it, and
exposes each evaluation entry point to it as a pure virtual method on
VerilatedModel. The model's 'eval' and 'eval_step' remain the top level
entry points, and are backward compatible.
V3Sched no longer emits '_eval' or '_eval_settle', etc.. Instead every
evaluation entry point called from the runtime is enumerated by 'VEval',
Scheduling creates all entry points, for all scheduling regions, even if
they are empty, and the runtime eval loop calls everything
unconditionally. If regions are empty, this is simply a call to an empty
function. This will hurt performance on very small models, but should
not be noticeable on anything meaningful, so it is likely best to keep
to reduce complexity.
A scheduling entry points evaluate a single iteration and returns
whether it did any work, they are effectively the previous
`_eval_phase_*` functions.
Introduce a new DfgPrev vertex, representing the value of a variable
before any in-graph assignments. This can be used to break all remaining
cycles in the graph, so all Dfgs become acyclic after V3DfgBreakCycles.
The circular dataflow is still represented, and is taken care of by the
scheduler, it is just the DfgGraph that represents the logic that
becomes acyclic.
This makes V3DfgBreakCycles a mandatory transform, so drop the disabling
-fno-dfg-break-cycles option (still parsed, but has no effect).
Note the effect of this is small, as most cycles can be fixed up by
driver tracing, which is unchanged, but this is required for some
upcoming work.
Wilson Snyder
David Harris
Tynan McAuley
Shriyans Sahoo
Geza Lore
Kaleb Barrett
Nick Brereton
Jesús Alberto López Soto
Edmund Lam
Mike Murunov
CatalpaEel
Marco Bartoli
Kristof Marien
Drew Risinger
Martijn Wobbes
Marco Frank
Drew Risinger
Paul Rigge
Jakub Wasilewski
Eddie Rydell
Aisha
Artur Bieniek
Aditya Shevade
Sunimali Rathnayake
Demin Han
Sumanth KadiyalaandSumanth Kadiyala
Paul Campbell
Tyrone Marhguy