This is a major re-design of the way code is scheduled in Verilator,
with the goal of properly supporting the Active and NBA regions of the
SystemVerilog scheduling model, as defined in IEEE 1800-2017 chapter 4.
With this change, all internally generated clocks should simulate
correctly, and there should be no more need for the `clock_enable` and
`clocker` attributes for correctness in the absence of Verilator
generated library models (`--lib-create`).
Details of the new scheduling model and algorithm are provided in
docs/internals.rst.
Implements #3278
The --prof-threads option has been split into two independent options:
1. --prof-exec, for collecting verilator_gantt and other execution
related profiling data, and
2. --prof-pgo, for collecting data needed for PGO
The implementation of execution profiling is extricated from
VlThreadPool and is now a separate class VlExecutionProfiler. This means
--prof-exec can now be used for single-threaded models (though it does
not measure a lot of things just yet). For consistency VerilatedProfiler
is renamed VlPgoProfiler. Both VlExecutionProfiler and VlPgoProfiler are
in verilated_profiler.{h/cpp}, but can be used completely independently.
Also re-worked the execution profile format so it now only emits events
without holding onto any temporaries. This is in preparation for some
future optimizations that would be hindered by the introduction of function
locals via AstText.
Also removed the Barrier event. Clearing the profile buffers is not
notably more expensive as the profiling records are trivially
destructible.
debug() declared by VL_DEGUB_FUNC used to cache the result of the debug
level lookup (which depends on options) in a static. This meant that if
the debug() function was called before option parsing, the default debug
level of 0 would be used for the rest of the program, even if a --debug
option was given. Fixed by not caching the debug level until after
option parsing is complete.
What previously used to be per module static constants created in
V3Table and V3Prelim are now merged globally within the whole model and
emitted as part of a separate constant pool. Members of the constant
pool are global variables which are declared lazily when used (similar to
loose methods).
Add V3OptionsParser that can suggest correct option.
Co-authored-by: Wilson Snyder <wsnyder@wsnyder.org>
Co-authored-by: github action <action@example.com>
This provides minor simulation performance benefit, but can provide
large C++ compilation time improvement, notably with Clang (4x).
This patch implements #2366 .
This adds the flag --generate-waivefile <filename>. This will generate
a verilator config file with the proper lint_off statemens to turn off
warnings emitted during this particular run.
This feature can be used to start with using Verilator as linter and
systematically capture all known lint warning for further
elimination. It hopefully helps people turning of -Wno-fatal or
-Wno-lint and gradually improve their code base.
Signed-off-by: Stefan Wallentowitz <stefan.wallentowitz@hm.edu>
Convert trace buffer to 32-bit entries, rather than a union containing a
pointer type. Also tweaked trace entry layouts for a bit more
performance. This gains another 10% on SweRV EH1 CoreMark.
The --trace-threads option can now be used to perform tracing on a
thread separate from the main thread when using VCD tracing (with
--trace-threads 1). For FST tracing --trace-threads can be 1 or 2, and
--trace-fst --trace-threads 1 is the same a what --trace-fst-threads
used to be (which is now deprecated).
Performance numbers on SweRV EH1 CoreMark, clang 6.0.0, Intel i7-3770 @
3.40GHz, IO to ramdisk, with numactl set to schedule threads on different
physical cores. Relative speedup:
--trace -> --trace --trace-threads 1 +22%
--trace-fst -> --trace-fst --trace-threads 1 +38% (as --trace-fst-thread)
--trace-fst -> --trace-fst --trace-threads 2 +93%
Speed relative to --trace with no threaded tracing:
--trace 1.00 x
--trace --trace-threads 1 0.82 x
--trace-fst 1.79 x
--trace-fst --trace-threads 1 1.23 x
--trace-fst --trace-threads 2 0.87 x
This means FST tracing with 2 extra threads is now faster than single
threaded VCD tracing, and is on par with threaded VCD tracing. You do
pay for it in total compute though as --trace-fst --trace-threads 2 uses
about 240% CPU vs 150% for --trace-fst --trace-threads 1, and 155% for
--trace --trace threads 1. Still for interactive use it should be
helpful with large designs.
Includes `timescale, $printtimescale, $timeformat.
VL_TIME_MULTIPLIER, VL_TIME_PRECISION, VL_TIME_UNIT have been removed
and the time precision must now match the SystemC time precision.
To get closer behavior to older versions, use e.g. --timescale-override
"1ps/1ps".
This switch exposes VARs, PORTs and WIREs to C++ code. It must be use
with care as it has a significant performance impact and may result in
mis-simulation of generated clocks. Anyhow, it is prefered over
--public and useful for VPI.
Signed-off-by: Lukasz Dalek <ldalek@antmicro.com>
Signed-off-by: Stefan Wallentowitz <stefan@wallentowitz.de>
Signed-off-by: Wilson Snyder <wsnyder@wsnyder.org>
Experimental and disabled unless -OD or -O3 used (for now),
Please try it as may get some significant speedups.
Signed-off-by: Wilson Snyder <wsnyder@wsnyder.org>
Geza Lore
Wilson Snyder
Yutetsu TAKATSUKASA
Stefan Wallentowitz
James Hanlon
Stefan Wallentowitz
Patrick Stewart
Todd Strader
Lukasz Dalek
Sergi Granell
johnjohnlin
John Coiner
Jeremy Bennett
Varun Koyyalagunta