a final parallel or series combination needs to be done but there
are still multiple property records. The multiplier was being
incorrectly applied twice, causing an automatic mismatch in
parameter values.
of multiple devices during flattening, that will skip over a node
record at the end of a subcircuit call being flattened and therefore
remove it from the netlist.
list that it prints in the side-by-side element mismatch comparison
for an element, when there is no node record associated with the pin
connection. This makes the output clearer.
swapped, so that if pin names are swapped on the top level, netgen will
report this as a final error message. Otherwise, the mismatch is only
reported back in the pin list where it is not obvious.
add properties across multiple property records in the last matching
step, if there are still multiple properties and the values can be
combined. Previously, netgen had been assuming that there would only
be one property record left at this point, which is not true. This
shows up particularly for BSIM fingered devices, since "nf" is
ignored.
run to the end of the list of circuit elements. Also corrected
another issue caused by the flag to denote multiple no-connect pins,
which can be on an instance pin and so cannot share the data from the
instance record.
device with one or more no-connect pins. The flag that indicates a
no-connect pin was checked incorrectly, potentially causing obscure
and misleading property mismatch messages to be generated.
unconnected pins in the other netlist are marked as "(no pin)"
rather than "(no matching pin)". This allows a script parsint the
JSON file (e.g., count_lvs.py from qflow) to distinguish between a
real pin error and one that can be ignored.
without netgen noticing---this behavior got broken by an
exception for "black box" circuits, but failed to check if the
circuit really was marked as a "black box" or not. Fixing that
revealed another issue with verilog implicit pins. Both issues
have now been corrected.
other devices that do not have a "critical property" that determines
which properties can add together was flawed and messed up the sorting
of devices like transistors and resistors that do have a critical
property. Reworked the sorting order so that it makes sense for both
situations.
Also corrected a superficial issue with an attempt to print out an
instance name that doesn't exist. There is an underlying bug here
related to cells that have no pins and/or no contents which has not
been debugged. The fix just keeps netgen from segfaulting.
different additive properties (like transistor width) to combine;
this is totally wrong and may have been left over from code written
before the routine was split into simple combinations (add similar
devices) and agressive combinations (e.g., add widths together).
class during setup, for the purpose of generating some derived
value that is used for merging and sorting, such as area = l*w.
Note that this likely needs adjusting so that the expression is
evaluated but not replaced for the purpose of sorting, since the
values to the parameter may change after parallel and series
merging.
cause inexplicable output in case of a property error by showing a
netlist topography error instead of a property error (but the output
shows that the netlists match, and there is no reporting of any
property errors). This error was discovered while implementing a
better sorting method for parallel combination. The improved method
sorts on two properties rather than one, and so should not fall into
the error where, say, devices are sorted on W but have different L
for a device like a capacitor where no "critical" property is
specified (and other similar cases, although that is a common one).
parallel and series devices. This was a fairly major error
undermining the property sorting (the case where the same number
of devices are in parallel in both circuits and need to be sorted
by, e.g., width, prior to checking for matches).
sides of the output when presenting side-by-side results. This
matches up net or device names within a partition. Where net or
device names match, the contents are also aligned on either side.
I attempted to also do a "best match" of contents between sides,
but as this involves a lot of analyzing the contents, it is very
computationally expensive, and so the code has been disabled. It
could be added back in as an option. There are also various ways
to optimize it for speed.
pins for enabling parallel combinations, which could cause a crash.
Added a "-force" option to "equate pins" to allow pins to be matched
even on subcircuits that did not correctly match; this was done in
conjuction with an extra option to the "lvs" command "-noflatten="
to pass a list of cellname to not be flattened even if they do not
match. This is generally discouraged, as it prevents netgen from
resolving differences between layout and schematic hierarchy, but it
can be useful for checking that the hierarchy above a certain cell
is correct, given that if a subcell is really unmatched, then its
errors will keep propagating up the top level, making additional
errors hard to diagnose.
devices in parallel with unconnected pins would be confused with
N devices in parallel with those pins all tied together. This is
treated as a property error.
to generate incorrect results on occasion. The method to parallelize
cells with the same no-connect pins should avoid the worst-case
symmetry breaking that was previously plaguing the LVS of large
standard-cell layouts.
to go into an infinite loop and fill memory until it crashes, due
to a complete pin mismatch between devices causing one device to
have its pins removed and replaced with proxy pins.
introduced in revision 150 can result in an incorrect result
reporting a bad match where the match is actually good (as proven
by running the full symmetry breaking on the same netlist).
Because the fast symmetry breaking is orders of magnitude faster
for large circuits, and because the false positive result appears
to be rare, I have introduced a command "symmetry" to switch
methods between fast and full. So fast symmetry breaking can be
run unless the result fails on symmetry breaking, in which case
the method can be switched to full to see if the problem is a
false positive or not. This is not an ideal solution, and some
investigation is needed to determine if there is a way to apply
fast symmetry breaking without encountering a false positive
error.
the top level circuits to be declared matching with no errors even
though the pins do not match. "proxy pins" are fine for subcells
to detect cases where one subcell has an unused pin and the matching
subcell does not declare it, but that should not be allowed on the
top level, as it cannot be known whether the pin is unused or not.
breaking by property was only matching properties between circuits but
not within the same circuit, which is needed for correct symmetry
breaking. But the PropertyMatch() routine assumed that it is passed
one item from each circuit, leading to a segfault when running the
symmetry breaking within a single circuit. This has been fixed.
that are not declared in the verilog netlist because they don't
connect to anything, and their presence is not required by verilog
syntax) and the printing of proxy pins created to act as placeholders
for those implicit pins. Also removed the pinting of the "disconnected
pin" messages for black-box modules (since by definition they have
disconnected pins, because black-box modules have no contents).
black-box circuits, especially those coming from verilog netlists
where a pin does not need to be declared and is implicitly floating.
This prevents the need to have an explicit black-box entry for any
verilog module that may have an instance that does not declare all
the pin connections. Also corrected an error which causes mysterious
failures if a verilog netlist is read before a SPICE netlist,
because the former gets hashed case-sensitive and the latter changes
the hashing to case-insensitive. Modified to force the SPICE
netlist to be treated case-sensitive, which may cause errors, but
is consistent with the reverse order handling, and doesn't cause
unexplained errors.
symmetry of all elements in all symmetric partitions, rather than
(as previously done) all elements in each partition, before re-
running iterations to convergence. This solves the problem of
having a very large number of partitions with a few elements each
taking a long time to run.
automorphisms so that it arbitrarily assigns all pairs from
circuit1 and circuit2 at once rather than assigning one pair at
a time and rerunning to convergence. I'm not sure of the validity
of this, other than that I have never seen a circuit fail to match
after resolving automorphisms, leading me to believe that the way
the symmetry breaking is done is irrelevant.
long run-times even when there are no properties to check. Corrected
a problem with SPICE and verilog netlist reading which arbitrarily
replaces file extensions even when a file extension is given,
resulting in reading the wrong file.
to include type CLASS_MODULE in the list of types to descend into,
since "module" (black-box) types need to be checked for pin
matching even if they have no contents. This allows two verilog
netlists to be compared against each other.
However, I have identified an issue that has not yet been resolved,
which is that there can be automorphisms that are potentially
broken by property matching. Currently, the automorphisms are
arbitrarily resolved, then properties are matched---and may fail
accordingly.
be removed because they do not match pins on the other cell being
compared, are marked with a different number (-2) than the usual
(-1). CleanupPins then only removes those pins that are marked,
rather than all disconnected pins.
<col2_width>" to set the output format width, to avoid the fixed column
widths of 41 characters which can truncate long strings in the output
such as deep cell hierarchies. This command can be placed in the setup
script to widen the output columns to accomodate the result (to-do:
provide an "auto" mode to automatically determine the best width).
a "critical property". This lets a device define multiple critical
properties, all of which must match before additive properties can
be combined in the same device.
re-worked property command, "critical" properties must match
across devices so that all other properties can be combined as
specified (addition, parallel combination, or none). The code was
still based on the older notion of the "critical" property being
the one to add (and thus preventing multiple properties from being
added in different ways). This has now been fixed.
handle verilog syntax. Also: Added SPICE voltage and current
sources as separate classes (as opposed to being converted to
subcircuits, which was how they were previously handled). That
allowed voltage sources to be checked for zero value and removed
by shorting the ends together, as was being done for zero value
resistors (note that like zero-value resistors, removal is only
done if removing the component makes a better match than leaving
it in). In particular, yosys has SPICE netlist output that
converts equality assignments ("assign a = b") into zero-value
voltage sources, so these components need to be treated as
non-physical elements.
the possibility that a device (e.g., resistor or capacitor) may
not be a semiconductor device (in other words, a parasitic or
ideal device), and therefore uses "value" but not width and
length, and therefore "value" is a critical property to merge
both in series and parallel. Corrected the series/parallel
network optimization to prevent it from setting both M and S
records > 1 on the same device (which is ambiguous). To try
to get number of devices to match, where there are both series
and parallel devices, they will be merged across the critical
property early (before property matching).
type double before sorting (previously, property promotion was
being done after parallel sorting). Also, modified the verilog
file reading so that parameters and definitions that are numeric
are stored as numeric (not string) properties.
determine if a parameter is a floating-point number, integer, or
string, and set the parameter accordingly. Found an error in the
parameter comparison if the subcircuit definitions don't agree
on the type of parameter. Now all values are promoted to a single
type based on preference order (double, integer, string). Tested
on a verilog file with a primitive device type defined as a module
with its properties encoded as parameters. This successfully
matched against the SPICE primitive device.
be in any specific order since all ports are named. Also corrected
problem with pin names not using the same string matching function
as used for nets in general (which affects the ability to match
against different bus delimiters).
Tim Edwards