decided that it is beneficial to break symmetries by net name;
it's just that net names should not be used before all symmetries
related to pins have been broken. So I rewrote the compare
routine to take an argument allowing or disallowing net name
matches, and make one call to break symmetries by pin name
followed by another call to break symmetries by net name. This
still solves the original problem, but does not allow symmetries
to be broken randomly on internal nets if names have been matched
in both netlists. Otherwise the output may report nets that
appear to be swapped, making the output confusing.
some errors failing to list in the output while also being responsible
for a number of non-errors showing up in the output. This fix may
substantially clean up netgen output. Also: Added text to the
output noting that pin matching may be incorrect with respect to
symmetries if the nets have failed to match.
pass the right cell name to the routine which counts the number of
pins. Using this in a setup file will prevent netgen from spending
time matching low-level devices.
with IRSIM including recent changes made to support multiple device
types using the subcircuit "x" component type. This requires
reading in a .prm file, which incidentally can be used with any
SPICE file to inform netgen of the specific component type of any
model defined as a subcircuit.
to have unique class hashes. This has the problem that it prevents
comparing N-to-1 cells because declaring X->X1 as equivalent breaks
the original name equivalence of X->X. The new implementation adds
the switch "-unique" to preserve the original behavior. Otherwise,
the class hashes are made the same as the 2nd cell passed to the
command, and it is the responsibility of the person running LVS to
ensure that this is done in the correct direction.
network parallel/series networks. Instead, added a global option
with command "property tolerance strict|relaxed" to reinstate the
original (strict) behavior on demand, while relaxing it by default.
This allows certain series/parallel networks to match numerically
even though the schematic netlist may have combined individual
devices.
the parallel sorting routine. This fixes occasional property
errors with series-connected devices such as resistors. (2) Added
a method to associate properties with specific pins when pins are
permutable. This allows netgen to properly check a value like
source/drain area when the definition of source and drain has
changed due to permutation of the device. (3) Added a "property"
command extension "associate" to associate a property with a pin,
for use with the method described in (2).
request #59 ("Pin match"). Because the pull request has rather
sweeping modifications, I am doing this in two steps. The change
that most breaks with existing comparison methods is in the
PinMatch() routine in netcmp.c, where the method of generating
proxy pins has been removed. There are specific cases for which
the proxy pin method exists, although these were coping with
issues arising from extraction in magic which have been dealt
with to some extend. Possibly the proxy pin method is no longer
needed. So the PinMatch() changes will be done in a second
commit where it's easier to revert or modify the changes without
affecting the modifications from this commit.
command option "flatten prohibit" (or "flatten deny") to prevent
a subcell from being flattened at any time during the compare
process. Previously, the "-noflatten" option for the "lvs"
script had been used to prevent flattening during initial
pre-match, but if the circuit passed the prematch phase and
subcells were mismatched, they would be flattened regardless of
whether or not they were listed by the "-noflatten" option. This
also codifies a way to prevent subcells from being flattened in
the setup file rather than in the "lvs" command line. Also:
Found and fixed a bug that prevents the use of "-noflatten=" with
a cell name or list of cell names instead of a filename.
should not be called after CreateTwoLists(). CreateTwoLists()
was being called in one case only to print the contents of the
cells, so that part was pulled out into a separate routine.
routine does not have an exact equivalent in PrematchLists() and
needs to be run beforehand. This fix keeps FlattenUnmatched()
from being run on all cells at the beginning and restricts it
to being run on the contents of individual cells during matching,
after checking if either of the cells is a black-box. Avoiding
flattening contents of one side when the other is a black-box
(or simply doesn't contain any subcircuits or devices) prevents
unnecessary flattening of cells that will never get compared.
This fixes crash on macos due to wrong hash() being linked in.
It also makes sure that proper function defs are declared and available
(as required by C99) to make compile possible in newer compilers (e.g.
Apple clang) and to some extend prevent similar linkage issues happening
again.
The algorithm is to run without exhaustive subdivision until the
last step because this is much faster. The final iteration must
be run with exhaustive subdivision on, or else it is possible to
have cells with swapped pins matching. The routines that resolve
automorphisms were setting exhaustive subdivision for the final
iteration. But simple "run converge" and "run resolve" were not.
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).
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.
can be turned on or off from the setup using "property parallel open"
to allow parallelizing devices with no-connect pins vs. "property
parallel connected" to only allow parallelizing of devices with all
pins connected.
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.
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.
with the file number, so that it can get confused between libraries.
Also made a fix to coerce one cell class to be forced to be the
same in both circuits under some circumstances.
are matched on circuits that have no elements. This condition
does not necessarily indicate an error, and matching pins has no
adverse affect (while refusing to match them certainly can).
in an "include" statement in either SPICE or verilog. Modified pin
matching behavior to force cells in both netlists to be marked as
black-box entries if either one is marked as a black-box entry (this
may not be needed, but shouldn't do any harm, either).
a different way of treating "black box" cells. Even when the
"-blackbox" option is specified, any cell that has no definition
will be treated as a black box. This allows comparison of a
black-box netlist against a non-black-box netlist, such as a
verilog netlist vs. a SPICE netlist, without forcing the black-box
attribute on the SPICE netlist. Then, if the SPICE netlist
contains cells without elements such as fill/decap/tap cells,
they can be flattened and removed instead of forcing an error or
requiring the use of "ignore".
<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).
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).
some problems stemming from comparing a case-sensitive netlist
against a case-insensitive one. Verilog netlist reading does
not yet have support for macros other than "`include", and it
does not yet have support for bit vectors constructed with
braces ({}).
calls "equate pins". This could fail because the routine that forces
uniqueness of pins was being called by the "compare" command but
outside of PinMatch. Fixed by duplicating the call to force uniqueness
of pins inside the "equate" function. Redundant calls should not
matter as uniqueness is resolved on the first call and subsequent calls
will need no further action.
for subcircuits (.subckt ... .ends pair with cellname and pin names
and pin order, but no contents) are automatically treated as black-
box circuits if found and if the "-blackbox" option is passed to the
"lvs" (scripted) command. The "equate pins" command can be used
outside of a comparison to force two circuits (black-box or
otherwise) to be matched by pin name (if not a black-box circuit,
then this is a provisional name match, as a circuit comparison will
order based on connectivity first, not pin names). So two sets of
black-box circuit libraries can be used as long as their pin names
match. One hack added to ignore the "!" at the end of global names
when comparing pin names for matching. Otherwise, pin names must
compare by case-insensitive string match.
documentation, and behaves as intended, which is that "-all" is
not a standalone option but is itself an optional qualifier to
the "cells <valid_cellname>" command. So the options are
"cells <valid_cellname>" and "cells -all <valid_cellname>".
treat empty subcircuits as blackbox cells automatically without
requiring specific callse to "model <cell> blackbox" for each.
Enabled in LVS script by giving option "-blackbox" at the end
of the LVS command.
Tim Edwards
Kamyar Mohajerani
D. Mitch Bailey