This allows compiling the run-time library with optimization even when OPT_FAST is not used in order to imporove model build speed, possibly during debug cycles.
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>
--output-split is now on by default with value 20000.
--output-split-cfuncs and --output-split-ctrace now defaults to the
value of --output-split unless explicitly specified.
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".
* Improve tracing performance.
Various tactics used to improve performance of both VCD and FST tracing:
- Both: Change tracing functions to templates to take variable widths as
template parameters. For VCD, subsequently specialize these to the
values used by Verilator. This avoids redundant instructions and hard
to predict branches.
- Both: Check for value changes via direct pointer access into the
previous signal value buffer. This eliminates a lot of simple pointer
arithmetic instructions form the tracing code.
- Both: Verilator provides clean input, no need to mask out used bits.
- VCD: pre-compute identifier codes and use memory copy instead of
re-computing them every time a code is emitted. This saves a lot of
instructions and hard to predict branches. The added D-cache misses
are cheaper than the removed branches/instructions.
- VCD: re-write the routines emitting the changes to be more efficient.
- FST: Use previous signal value buffer the same way as the VCD tracing
code, and only call the FST API when a change is detected.
Performance as measured on SweRV EH1, with the pre-canned CoreMark
benchmark running from DCCM/ICCM, clang 6.0.0, Intel i7-3770 @ 3.40GHz,
and IO to ramdisk:
+--------------+---------------+----------------------+
| VCD | FST | FST separate thread |
| (--trace) | (--trace-fst) | (--trace-fst-thread) |
------------+-----------------------------------------------------+
Before | 30.2 s | 121.1 s | 69.8 s |
============+==============+===============+======================+
After | 24.7 s | 45.7 s | 32.4 s |
------------+--------------+---------------+----------------------+
Speedup | 22 % | 256 % | 215 % |
------------+--------------+---------------+----------------------+
Rel. to VCD | 1 x | 1.85 x | 1.31 x |
------------+--------------+---------------+----------------------+
In addition, FST trace size for the above reduced by 48%.
This looks like a bits/bytes bug. The affected m_codeInc member
determines how many 32-bit words to allocate in a buffer used to store
previous values of the signal, but this was off by a factor of 8, so
we used to use too much memory.
SweRV VCD tracing speed +6.5% (excluding IO, clang 6.0), due mainly to
reduced D cache misses.
When using the __ALL*.cpp based single compile mode (i.e.: without
VM_PARALLEL_BUILDS), the fast path tracing code used to be included in
__Allsup.cpp, which was compiled with OPT_SLOW, severely harming tracing
performance. We now have __ALLfast.cpp and __ALLslow.cpp instead of
__ALLcls.cpp and __ALLsup.cpp, so we can compile the fast support code
with OPT_FAST as well.
This patch eliminates a major piece of inefficiency in FST tracing
support, by using an array to lookup fstHandle values corresponding
to trace codes, instead of a tree based std::map. With this change, FST
tracing is now only about 3x slower than VCD tracing. We do require
more memory to store the symbol lookup table, but the size of that is
still small, for the speed benefit.
* Add +verilator+noassert flag
This allows to disable the assert check per simulation argument.
* Add AssertOn check for assert
Insert the check AssertOn to allow disabling of asserts.
Asserts can be disabled by not using the `--assert` flag or by calling
`AssertOn(false)`, or passing the "+verilator+noassert" runtime flag.
Add tests for this behavior.
Bad tests check that the assert still causes a stop.
Non bad tests check that asserts are properly disabled and cause no stop
of the simulation.
Fixes#2162.
Signed-off-by: Tobias Wölfel <tobias.woelfel@mailbox.org>
* Correct file location
Signed-off-by: Tobias Wölfel <tobias.woelfel@mailbox.org>
* Add description for single test execution
Without this description it is not obvious how to run a single test from
the regression test suite.
Signed-off-by: Tobias Wölfel <tobias.woelfel@mailbox.org>
The build is now by default configured to link performance critical
libraries (libgcc, libstdc++, libtcmalloc) statically. This improves
Verilation speed by between 4.5-7% based on my measurements as it
eliminates approx 20% of the mispredicted branches from the execution.
With partial static linking, the size of the .text section in
verilator_bin is increased by about 14%, and the binary is itself only
about 800KB bigger on disk, so hopefully this is not a big issue in
exchange for the faster compilation speed. A configure option
"--disable-partial-static" is provided to restore the old behaviour of
linking everything dynamically.
Note: This patch also changes to use libtcmalloc_minimal, which is all
we really need and itself has fewer dependencies.
Replace the virtual type() method on AstNode with a non-virtual, inlined
accessor to a const member variable m_type. This means that in order to be
able to use this for type testing, it needs to be initialized based on the
final type of the node. This is achieved by passing the relevant AstType
value back through the constructor call chain. Most of the boilerplate
involved is auto generated by first feeding V3AstNodes.h through astgen to
get V3AstNodes__gen.h, which is then included in V3Ast.h. No client code
needs to be aware and there is no functional change intended.
Eliminating the virtual function call to fetch the node type identifier
results in measured compilation speed improvement of 5-10% as it
eliminates up to 20% of all mispredicted branches from the execution.
As Verilator continuously allocates and releases small objects (e.g.:
AstNode, V3GraphVertex, V3GraphEdge), it spends a significant amount of
time in malloc/free and friends. This patch adds the --enable-tcmalloc
configure option to link Verilator against the high performance malloc
implementation library libtcmalloc. The default is to use libtcmalloc if
available on the system. Note that there are no source code change, we
are simply replacing the standard library memory allocation functions.
Measured major compilation speed improvement of 27% when running
Verilator with -O3 on a large design.
* Add detailed location to XML output
* Fixing build failures
* less cryptic regulary expressions
* correcting typo in test
* Adding file letter to the location attribute, and cleaning up the regular expression in the tests.
* Add remaining test expected output files for XML changes
* spacing fix, adding documentation on changes
* Add more directives to configuration files
Allow to set the same directives in configuration files that can also
be set by comment attributes (such as /* verilator public */ etc).
* Add support for lint messsage waivers
Add configuration file switch '-match' for lint_off. It takes a string
with wildcards allowed and warnings will be matched against it (if
rule and file also match). If it matches, the warning is waived.
Fixes#1649 and #1514Closes#2072