yosys/backends/smt2/smtbmc.py

#!/usr/bin/env python3
#
# yosys -- Yosys Open SYnthesis Suite
#
# Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#

import os, sys, getopt, re
##yosys-sys-path##
from smtio import SmtIo, SmtOpts, MkVcd
from collections import defaultdict

got_topt = False
skip_steps = 0
step_size = 1
num_steps = 20
append_steps = 0
vcdfile = None
cexfile = None
aimfile = None
aiwfile = None
aigheader = True
btorwitfile = None
vlogtbfile = None
vlogtbtop = None
inconstr = list()
outconstr = None
gentrace = False
covermode = False
tempind = False
dumpall = False
assume_skipped = None
final_only = False
topmod = None
noinfo = False
presat = False
smtcinit = False
smtctop = None
noinit = False
binarymode = False
so = SmtOpts()


def usage():
    print(os.path.basename(sys.argv[0]) + """ [options] <yosys_smt2_output>

    -t <num_steps>
    -t <skip_steps>:<num_steps>
    -t <skip_steps>:<step_size>:<num_steps>
        default: skip_steps=0, step_size=1, num_steps=20

    -g
        generate an arbitrary trace that satisfies
        all assertions and assumptions.

    -i
        instead of BMC run temporal induction

    -c
        instead of regular BMC run cover analysis

    -m <module_name>
        name of the top module

    --smtc <constr_filename>
        read constraints file

    --cex <cex_filename>
        read cex file as written by ABC's "write_cex -n"

    --aig <prefix>
        read AIGER map file (as written by Yosys' "write_aiger -map")
        and AIGER witness file. The file names are <prefix>.aim for
        the map file and <prefix>.aiw for the witness file.

    --aig <aim_filename>:<aiw_filename>
        like above, but for map files and witness files that do not
        share a filename prefix (or use different file extensions).

    --aig-noheader
        the AIGER witness file does not include the status and
        properties lines.

    --btorwit <btor_witness_filename>
        read a BTOR witness.

    --noinfo
        only run the core proof, do not collect and print any
        additional information (e.g. which assert failed)

    --presat
        check if the design with assumptions but without assertions
        is SAT before checking if assertions are UNSAT. This will
        detect if there are contradicting assumptions. In some cases
        this will also help to "warm up" the solver, potentially
        yielding a speedup.

    --final-only
        only check final constraints, assume base case

    --assume-skipped <start_step>
        assume asserts in skipped steps in BMC.
        no assumptions are created for skipped steps
        before <start_step>.

    --dump-vcd <vcd_filename>
        write trace to this VCD file
        (hint: use 'write_smt2 -wires' for maximum
        coverage of signals in generated VCD file)

    --dump-vlogtb <verilog_filename>
        write trace as Verilog test bench

    --vlogtb-top <hierarchical_name>
        use the given entity as top module for the generated
        Verilog test bench. The <hierarchical_name> is relative
        to the design top module without the top module name.

    --dump-smtc <constr_filename>
        write trace as constraints file

    --smtc-init
        write just the last state as initial constraint to smtc file

    --smtc-top <old>[:<new>]
        replace <old> with <new> in constraints dumped to smtc
        file and only dump object below <old> in design hierarchy.

    --noinit
        do not assume initial conditions in state 0

    --dump-all
        when using -g or -i, create a dump file for each
        step. The character '%' is replaces in all dump
        filenames with the step number.

    --append <num_steps>
        add <num_steps> time steps at the end of the trace
        when creating a counter example (this additional time
        steps will still be constrained by assumptions)

    --binary
        dump anyconst values as raw bit strings
""" + so.helpmsg())
    sys.exit(1)


try:
    opts, args = getopt.getopt(sys.argv[1:], so.shortopts + "t:igcm:", so.longopts +
            ["final-only", "assume-skipped=", "smtc=", "cex=", "aig=", "aig-noheader", "btorwit=", "presat",
             "dump-vcd=", "dump-vlogtb=", "vlogtb-top=", "dump-smtc=", "dump-all", "noinfo", "append=",
             "smtc-init", "smtc-top=", "noinit", "binary"])
except:
    usage()

for o, a in opts:
    if o == "-t":
        got_topt = True
        a = a.split(":")
        if len(a) == 1:
            num_steps = int(a[0])
        elif len(a) == 2:
            skip_steps = int(a[0])
            num_steps = int(a[1])
        elif len(a) == 3:
            skip_steps = int(a[0])
            step_size = int(a[1])
            num_steps = int(a[2])
        else:
            assert False
    elif o == "--assume-skipped":
        assume_skipped = int(a)
    elif o == "--final-only":
        final_only = True
    elif o == "--smtc":
        inconstr.append(a)
    elif o == "--cex":
        cexfile = a
    elif o == "--aig":
        if ":" in a:
            aimfile, aiwfile = a.split(":")
        else:
            aimfile = a + ".aim"
            aiwfile = a + ".aiw"
    elif o == "--aig-noheader":
        aigheader = False
    elif o == "--btorwit":
        btorwitfile = a
    elif o == "--dump-vcd":
        vcdfile = a
    elif o == "--dump-vlogtb":
        vlogtbfile = a
    elif o == "--vlogtb-top":
        vlogtbtop = a
    elif o == "--dump-smtc":
        outconstr = a
    elif o == "--smtc-init":
        smtcinit = True
    elif o == "--smtc-top":
        smtctop = a.split(":")
        if len(smtctop) == 1:
            smtctop.append("")
        assert len(smtctop) == 2
        smtctop = tuple(smtctop)
    elif o == "--dump-all":
        dumpall = True
    elif o == "--presat":
        presat = True
    elif o == "--noinfo":
        noinfo = True
    elif o == "--noinit":
        noinit = True
    elif o == "--append":
        append_steps = int(a)
    elif o == "-i":
        tempind = True
    elif o == "-g":
        gentrace = True
    elif o == "-c":
        covermode = True
    elif o == "-m":
        topmod = a
    elif o == "--binary":
        binarymode = True
    elif so.handle(o, a):
        pass
    else:
        usage()

if len(args) != 1:
    usage()

if sum([tempind, gentrace, covermode]) > 1:
    usage()

constr_final_start = None
constr_asserts = defaultdict(list)
constr_assumes = defaultdict(list)
constr_write = list()

for fn in inconstr:
    current_states = None
    current_line = 0

    with open(fn, "r") as f:
        for line in f:
            current_line += 1

            if line.startswith("#"):
                continue

            tokens = line.split()

            if len(tokens) == 0:
                continue

            if tokens[0] == "initial":
                current_states = set()
                if not tempind:
                    current_states.add(0)
                continue

            if tokens[0] == "final":
                constr_final = True
                if len(tokens) == 1:
                    current_states = set(["final-%d" % i for i in range(0, num_steps+1)])
                    constr_final_start = 0
                elif len(tokens) == 2:
                    arg = abs(int(tokens[1]))
                    current_states = set(["final-%d" % i for i in range(arg, num_steps+1)])
                    constr_final_start = arg if constr_final_start is None else min(constr_final_start, arg)
                else:
                    assert False
                continue

            if tokens[0] == "state":
                current_states = set()
                if not tempind:
                    for token in tokens[1:]:
                        tok = token.split(":")
                        if len(tok) == 1:
                            current_states.add(int(token))
                        elif len(tok) == 2:
                            lower = int(tok[0])
                            if tok[1] == "*":
                                upper = num_steps
                            else:
                                upper = int(tok[1])
                            for i in range(lower, upper+1):
                                current_states.add(i)
                        else:
                            assert False
                continue

            if tokens[0] == "always":
                if len(tokens) == 1:
                    current_states = set(range(0, num_steps+1))
                elif len(tokens) == 2:
                    arg = abs(int(tokens[1]))
                    current_states = set(range(arg, num_steps+1))
                else:
                    assert False
                continue

            if tokens[0] == "assert":
                assert current_states is not None

                for state in current_states:
                    constr_asserts[state].append(("%s:%d" % (fn, current_line), " ".join(tokens[1:])))

                continue

            if tokens[0] == "assume":
                assert current_states is not None

                for state in current_states:
                    constr_assumes[state].append(("%s:%d" % (fn, current_line), " ".join(tokens[1:])))

                continue

            if tokens[0] == "write":
                constr_write.append(" ".join(tokens[1:]))
                continue

            if tokens[0] == "logic":
                so.logic = " ".join(tokens[1:])
                continue

            assert False


def get_constr_expr(db, state, final=False, getvalues=False):
    if final:
        if ("final-%d" % state) not in db:
            return ([], [], []) if getvalues else "true"
    else:
        if state not in db:
            return ([], [], []) if getvalues else "true"

    netref_regex = re.compile(r'(^|[( ])\[(-?[0-9]+:|)([^\]]*|\S*)\](?=[ )]|$)')

    def replace_netref(match):
        state_sel = match.group(2)

        if state_sel == "":
            st = state
        elif state_sel[0] == "-":
            st = state + int(state_sel[:-1])
        else:
            st = int(state_sel[:-1])

        expr = smt.net_expr(topmod, "s%d" % st, smt.get_path(topmod, match.group(3)))

        return match.group(1) + expr

    expr_list = list()
    for loc, expr in db[("final-%d" % state) if final else state]:
        actual_expr = netref_regex.sub(replace_netref, expr)
        if getvalues:
            expr_list.append((loc, expr, actual_expr))
        else:
            expr_list.append(actual_expr)

    if getvalues:
        loc_list, expr_list, acual_expr_list = zip(*expr_list)
        value_list = smt.get_list(acual_expr_list)
        return loc_list, expr_list, value_list

    if len(expr_list) == 0:
        return "true"

    if len(expr_list) == 1:
        return expr_list[0]

    return "(and %s)" % " ".join(expr_list)


smt = SmtIo(opts=so)

if noinfo and vcdfile is None and vlogtbfile is None and outconstr is None:
    smt.produce_models = False

def print_msg(msg):
    print("%s %s" % (smt.timestamp(), msg))
    sys.stdout.flush()

print_msg("Solver: %s" % (so.solver))

with open(args[0], "r") as f:
    for line in f:
        smt.write(line)

for line in constr_write:
    smt.write(line)

if topmod is None:
    topmod = smt.topmod

assert topmod is not None
assert topmod in smt.modinfo

if cexfile is not None:
    if not got_topt:
        assume_skipped = 0
        skip_steps = 0
        num_steps = 0

    with open(cexfile, "r") as f:
        cex_regex = re.compile(r'([^\[@=]+)(\[\d+\])?([^@=]*)(@\d+)=([01])')
        for entry in f.read().split():
            match = cex_regex.match(entry)
            assert match

            name, bit, extra_name, step, val = match.group(1), match.group(2), match.group(3), match.group(4), match.group(5)

            if extra_name != "":
                continue

            if name not in smt.modinfo[topmod].inputs:
                continue

            if bit is None:
                bit = 0
            else:
                bit = int(bit[1:-1])

            step = int(step[1:])
            val = int(val)

            if smt.modinfo[topmod].wsize[name] == 1:
                assert bit == 0
                smtexpr = "(= [%s] %s)" % (name, "true" if val else "false")
            else:
                smtexpr = "(= ((_ extract %d %d) [%s]) #b%d)" % (bit, bit, name, val)

            # print("cex@%d: %s" % (step, smtexpr))
            constr_assumes[step].append((cexfile, smtexpr))

            if not got_topt:
                skip_steps = max(skip_steps, step)
                num_steps = max(num_steps, step+1)

if aimfile is not None:
    input_map = dict()
    init_map = dict()
    latch_map = dict()

    if not got_topt:
        assume_skipped = 0
        skip_steps = 0
        num_steps = 0

    with open(aimfile, "r") as f:
        for entry in f.read().splitlines():
            entry = entry.split()

            if entry[0] == "input":
                input_map[int(entry[1])] = (entry[3], int(entry[2]))
                continue

            if entry[0] == "init":
                init_map[int(entry[1])] = (entry[3], int(entry[2]))
                continue

            if entry[0] in ["latch", "invlatch"]:
                latch_map[int(entry[1])] = (entry[3], int(entry[2]), entry[0] == "invlatch")
                continue

            if entry[0] in ["output", "wire"]:
                continue

            assert False

    with open(aiwfile, "r") as f:
        got_state = False
        got_ffinit = False
        step = 0

        if not aigheader:
            got_state = True

        for entry in f.read().splitlines():
            if len(entry) == 0 or entry[0] in "bcjfu.":
                continue

            if not got_state:
                got_state = True
                assert entry == "1"
                continue

            if not got_ffinit:
                got_ffinit = True
                if len(init_map) == 0:
                    for i in range(len(entry)):
                        if entry[i] == "x":
                            continue

                        if i in latch_map:
                            value = int(entry[i])
                            name = latch_map[i][0]
                            bitidx = latch_map[i][1]
                            invert = latch_map[i][2]

                            if invert:
                                value = 1 - value

                            path = smt.get_path(topmod, name)
                            width = smt.net_width(topmod, path)

                            if width == 1:
                                assert bitidx == 0
                                smtexpr = "(= [%s] %s)" % (name, "true" if value else "false")
                            else:
                                smtexpr = "(= ((_ extract %d %d) [%s]) #b%d)" % (bitidx, bitidx, name, value)

                            constr_assumes[0].append((cexfile, smtexpr))
                continue

            for i in range(len(entry)):
                if entry[i] == "x":
                    continue

                if (step == 0) and (i in init_map):
                    value = int(entry[i])
                    name = init_map[i][0]
                    bitidx = init_map[i][1]

                    path = smt.get_path(topmod, name)

                    if not smt.net_exists(topmod, path):
                        match = re.match(r"(.*)\[(\d+)\]$", path[-1])
                        if match:
                            path[-1] = match.group(1)
                            addr = int(match.group(2))

                        if not match or not smt.mem_exists(topmod, path):
                            print_msg("Ignoring init value for unknown net: %s" % (name))
                            continue

                        meminfo = smt.mem_info(topmod, path)
                        smtexpr = "(select [%s] #b%s)" % (".".join(path), bin(addr)[2:].zfill(meminfo[0]))
                        width = meminfo[1]

                    else:
                        smtexpr = "[%s]" % name
                        width = smt.net_width(topmod, path)

                    if width == 1:
                        assert bitidx == 0
                        smtexpr = "(= %s %s)" % (smtexpr, "true" if value else "false")
                    else:
                        smtexpr = "(= ((_ extract %d %d) %s) #b%d)" % (bitidx, bitidx, smtexpr, value)

                    constr_assumes[0].append((cexfile, smtexpr))

                if i in input_map:
                    value = int(entry[i])
                    name = input_map[i][0]
                    bitidx = input_map[i][1]

                    path = smt.get_path(topmod, name)
                    width = smt.net_width(topmod, path)

                    if width == 1:
                        assert bitidx == 0
                        smtexpr = "(= [%s] %s)" % (name, "true" if value else "false")
                    else:
                        smtexpr = "(= ((_ extract %d %d) [%s]) #b%d)" % (bitidx, bitidx, name, value)

                    constr_assumes[step].append((cexfile, smtexpr))

            if not got_topt:
                skip_steps = max(skip_steps, step)
                num_steps = max(num_steps, step+1)
            step += 1

if btorwitfile is not None:
    with open(btorwitfile, "r") as f:
        step = None
        suffix = None
        altsuffix = None
        header_okay = False

        for line in f:
            line = line.strip()

            if line == "sat":
                header_okay = True
                continue

            if not header_okay:
                continue

            if line == "" or line[0] == "b" or line[0] == "j":
                continue

            if line == ".":
                break

            if line[0] == '#' or line[0] == '@':
                step = int(line[1:])
                suffix = line
                altsuffix = suffix
                if suffix[0] == "@":
                    altsuffix = "#" + suffix[1:]
                else:
                    altsuffix = "@" + suffix[1:]
                continue

            line = line.split()

            if len(line) == 0:
                continue

            if line[-1].endswith(suffix):
                line[-1] = line[-1][0:len(line[-1]) - len(suffix)]

            if line[-1].endswith(altsuffix):
                line[-1] = line[-1][0:len(line[-1]) - len(altsuffix)]

            if line[-1][0] == "$":
                continue

            # BV assignments
            if len(line) == 3 and line[1][0] != "[":
                value = line[1]
                name = line[2]

                path = smt.get_path(topmod, name)

                if not smt.net_exists(topmod, path):
                    continue

                width = smt.net_width(topmod, path)

                if width == 1:
                    assert value in ["0", "1"]
                    value = "true" if value == "1" else "false"
                else:
                    value = "#b" + value

                smtexpr = "(= [%s] %s)" % (name, value)
                constr_assumes[step].append((btorwitfile, smtexpr))

            # Array assignments
            if len(line) == 4 and line[1][0] == "[":
                index = line[1]
                value = line[2]
                name = line[3]

                path = smt.get_path(topmod, name)

                if not smt.mem_exists(topmod, path):
                    continue

                meminfo = smt.mem_info(topmod, path)

                if meminfo[1] == 1:
                    assert value in ["0", "1"]
                    value = "true" if value == "1" else "false"
                else:
                    value = "#b" + value

                assert index[0] == "["
                assert index[-1] == "]"
                index = "#b" + index[1:-1]

                smtexpr = "(= (select [%s] %s) %s)" % (name, index, value)
                constr_assumes[step].append((btorwitfile, smtexpr))

        skip_steps = step
        num_steps = step+1

def write_vcd_trace(steps_start, steps_stop, index):
    filename = vcdfile.replace("%", index)
    print_msg("Writing trace to VCD file: %s" % (filename))

    with open(filename, "w") as vcd_file:
        vcd = MkVcd(vcd_file)
        path_list = list()

        for netpath in sorted(smt.hiernets(topmod)):
            hidden_net = False
            for n in netpath:
                if n.startswith("$"):
                    hidden_net = True
            if not hidden_net:
                edge = smt.net_clock(topmod, netpath)
                if edge is None:
                    vcd.add_net([topmod] + netpath, smt.net_width(topmod, netpath))
                else:
                    vcd.add_clock([topmod] + netpath, edge)
                path_list.append(netpath)

        mem_trace_data = dict()
        for mempath in sorted(smt.hiermems(topmod)):
            abits, width, rports, wports, asyncwr = smt.mem_info(topmod, mempath)

            expr_id = list()
            expr_list = list()
            for i in range(steps_start, steps_stop):
                for j in range(rports):
                    expr_id.append(('R', i-steps_start, j, 'A'))
                    expr_id.append(('R', i-steps_start, j, 'D'))
                    expr_list.append(smt.mem_expr(topmod, "s%d" % i, mempath, "R%dA" % j))
                    expr_list.append(smt.mem_expr(topmod, "s%d" % i, mempath, "R%dD" % j))
                for j in range(wports):
                    expr_id.append(('W', i-steps_start, j, 'A'))
                    expr_id.append(('W', i-steps_start, j, 'D'))
                    expr_id.append(('W', i-steps_start, j, 'M'))
                    expr_list.append(smt.mem_expr(topmod, "s%d" % i, mempath, "W%dA" % j))
                    expr_list.append(smt.mem_expr(topmod, "s%d" % i, mempath, "W%dD" % j))
                    expr_list.append(smt.mem_expr(topmod, "s%d" % i, mempath, "W%dM" % j))

            rdata = list()
            wdata = list()
            addrs = set()

            for eid, edat in zip(expr_id, smt.get_list(expr_list)):
                t, i, j, f = eid

                if t == 'R':
                    c = rdata
                elif t == 'W':
                    c = wdata
                else:
                    assert False

                while len(c) <= i:
                    c.append(list())
                c = c[i]

                while len(c) <= j:
                    c.append(dict())
                c = c[j]

                c[f] = smt.bv2bin(edat)

                if f == 'A':
                    addrs.add(c[f])

            for addr in addrs:
                tdata = list()
                data = ["x"] * width
                gotread = False

                if len(wdata) == 0 and len(rdata) != 0:
                    wdata = [[]] * len(rdata)

                assert len(rdata) == len(wdata)

                for i in range(len(wdata)):
                    if not gotread:
                        for j_data in rdata[i]:
                            if j_data["A"] == addr:
                                data = list(j_data["D"])
                                gotread = True
                                break

                        if gotread:
                            buf = data[:]
                            for i in reversed(range(len(tdata))):
                                for k in range(width):
                                    if tdata[i][k] == "x":
                                        tdata[i][k] = buf[k]
                                    else:
                                        buf[k] = tdata[i][k]

                    if not asyncwr:
                        tdata.append(data[:])

                    for j_data in wdata[i]:
                        if j_data["A"] != addr:
                            continue

                        D = j_data["D"]
                        M = j_data["M"]

                        for k in range(width):
                            if M[k] == "1":
                                data[k] = D[k]

                    if asyncwr:
                        tdata.append(data[:])

                assert len(tdata) == len(rdata)

                netpath = mempath[:]
                netpath[-1] += "<%0*x>" % ((len(addr)+3) // 4, int(addr, 2))
                vcd.add_net([topmod] + netpath, width)

                for i in range(steps_start, steps_stop):
                    if i not in mem_trace_data:
                        mem_trace_data[i] = list()
                    mem_trace_data[i].append((netpath, "".join(tdata[i-steps_start])))

        for i in range(steps_start, steps_stop):
            vcd.set_time(i)
            value_list = smt.get_net_bin_list(topmod, path_list, "s%d" % i)
            for path, value in zip(path_list, value_list):
                vcd.set_net([topmod] + path, value)
            if i in mem_trace_data:
                for path, value in mem_trace_data[i]:
                    vcd.set_net([topmod] + path, value)

        vcd.set_time(steps_stop)


def write_vlogtb_trace(steps_start, steps_stop, index):
    filename = vlogtbfile.replace("%", index)
    print_msg("Writing trace to Verilog testbench: %s" % (filename))

    vlogtb_topmod = topmod
    vlogtb_state = "s@@step_idx@@"

    if vlogtbtop is not None:
        for item in vlogtbtop.split("."):
            if item in smt.modinfo[vlogtb_topmod].cells:
                vlogtb_state = "(|%s_h %s| %s)" % (vlogtb_topmod, item, vlogtb_state)
                vlogtb_topmod = smt.modinfo[vlogtb_topmod].cells[item]
            else:
                print_msg("Vlog top module '%s' not found: no cell '%s' in module '%s'" % (vlogtbtop, item, vlogtb_topmod))
                break

    with open(filename, "w") as f:
        print("`ifndef VERILATOR", file=f)
        print("module testbench;", file=f)
        print("  reg [4095:0] vcdfile;", file=f)
        print("  reg clock;", file=f)
        print("`else", file=f)
        print("module testbench(input clock, output reg genclock);", file=f)
        print("  initial genclock = 1;", file=f)
        print("`endif", file=f)

        print("  reg genclock = 1;", file=f)
        print("  reg [31:0] cycle = 0;", file=f)

        primary_inputs = list()
        clock_inputs = set()

        for name in smt.modinfo[vlogtb_topmod].inputs:
            if name in ["clk", "clock", "CLK", "CLOCK"]:
                clock_inputs.add(name)
            width = smt.modinfo[vlogtb_topmod].wsize[name]
            primary_inputs.append((name, width))

        for name, width in primary_inputs:
            if name in clock_inputs:
                print("  wire [%d:0] PI_%s = clock;" % (width-1, name), file=f)
            else:
                print("  reg [%d:0] PI_%s;" % (width-1, name), file=f)

        print("  %s UUT (" % vlogtb_topmod, file=f)
        print(",\n".join("    .{name}(PI_{name})".format(name=name) for name, _ in primary_inputs), file=f)
        print("  );", file=f)

        print("`ifndef VERILATOR", file=f)
        print("  initial begin", file=f)
        print("    if ($value$plusargs(\"vcd=%s\", vcdfile)) begin", file=f)
        print("      $dumpfile(vcdfile);", file=f)
        print("      $dumpvars(0, testbench);", file=f)
        print("    end", file=f)
        print("    #5 clock = 0;", file=f)
        print("    while (genclock) begin", file=f)
        print("      #5 clock = 0;", file=f)
        print("      #5 clock = 1;", file=f)
        print("    end", file=f)
        print("  end", file=f)
        print("`endif", file=f)

        print("  initial begin", file=f)

        regs = sorted(smt.hiernets(vlogtb_topmod, regs_only=True))
        regvals = smt.get_net_bin_list(vlogtb_topmod, regs, vlogtb_state.replace("@@step_idx@@", str(steps_start)))

        print("`ifndef VERILATOR", file=f)
        print("    #1;", file=f)
        print("`endif", file=f)
        for reg, val in zip(regs, regvals):
            hidden_net = False
            for n in reg:
                if n.startswith("$"):
                    hidden_net = True
            print("    %sUUT.%s = %d'b%s;" % ("// " if hidden_net else "", ".".join(reg), len(val), val), file=f)

        anyconsts = sorted(smt.hieranyconsts(vlogtb_topmod))
        for info in anyconsts:
            if info[3] is not None:
                modstate = smt.net_expr(vlogtb_topmod, vlogtb_state.replace("@@step_idx@@", str(steps_start)), info[0])
                value = smt.bv2bin(smt.get("(|%s| %s)" % (info[1], modstate)))
                print("    UUT.%s = %d'b%s;" % (".".join(info[0] + [info[3]]), len(value), value), file=f);

        mems = sorted(smt.hiermems(vlogtb_topmod))
        for mempath in mems:
            abits, width, rports, wports, asyncwr = smt.mem_info(vlogtb_topmod, mempath)

            addr_expr_list = list()
            data_expr_list = list()
            for i in range(steps_start, steps_stop):
                for j in range(rports):
                    addr_expr_list.append(smt.mem_expr(vlogtb_topmod, vlogtb_state.replace("@@step_idx@@", str(i)), mempath, "R%dA" % j))
                    data_expr_list.append(smt.mem_expr(vlogtb_topmod, vlogtb_state.replace("@@step_idx@@", str(i)), mempath, "R%dD" % j))

            addr_list = smt.get_list(addr_expr_list)
            data_list = smt.get_list(data_expr_list)

            addr_data = dict()
            for addr, data in zip(addr_list, data_list):
                addr = smt.bv2bin(addr)
                data = smt.bv2bin(data)
                if addr not in addr_data:
                    addr_data[addr] = data

            for addr, data in addr_data.items():
                print("    UUT.%s[%d'b%s] = %d'b%s;" % (".".join(mempath), len(addr), addr, len(data), data), file=f)

        print("", file=f)
        anyseqs = sorted(smt.hieranyseqs(vlogtb_topmod))

        for i in range(steps_start, steps_stop):
            pi_names = [[name] for name, _ in primary_inputs if name not in clock_inputs]
            pi_values = smt.get_net_bin_list(vlogtb_topmod, pi_names, vlogtb_state.replace("@@step_idx@@", str(i)))

            print("    // state %d" % i, file=f)

            if i > 0:
                print("    if (cycle == %d) begin" % (i-1), file=f)

            for name, val in zip(pi_names, pi_values):
                if i > 0:
                    print("      PI_%s <= %d'b%s;" % (".".join(name), len(val), val), file=f)
                else:
                    print("    PI_%s = %d'b%s;" % (".".join(name), len(val), val), file=f)

            for info in anyseqs:
                if info[3] is not None:
                    modstate = smt.net_expr(vlogtb_topmod, vlogtb_state.replace("@@step_idx@@", str(i)), info[0])
                    value = smt.bv2bin(smt.get("(|%s| %s)" % (info[1], modstate)))
                    if i > 0:
                        print("      UUT.%s <= %d'b%s;" % (".".join(info[0] + [info[3]]), len(value), value), file=f);
                    else:
                        print("    UUT.%s = %d'b%s;" % (".".join(info[0] + [info[3]]), len(value), value), file=f);

            if i > 0:
                print("    end", file=f)
                print("", file=f)

            if i == 0:
                print("  end", file=f)
                print("  always @(posedge clock) begin", file=f)

        print("    genclock <= cycle < %d;" % (steps_stop-1), file=f)
        print("    cycle <= cycle + 1;", file=f)
        print("  end", file=f)

        print("endmodule", file=f)


def write_constr_trace(steps_start, steps_stop, index):
    filename = outconstr.replace("%", index)
    print_msg("Writing trace to constraints file: %s" % (filename))

    constr_topmod = topmod
    constr_state = "s@@step_idx@@"
    constr_prefix = ""

    if smtctop is not None:
        for item in smtctop[0].split("."):
            assert item in smt.modinfo[constr_topmod].cells
            constr_state = "(|%s_h %s| %s)" % (constr_topmod, item, constr_state)
            constr_topmod = smt.modinfo[constr_topmod].cells[item]
        if smtctop[1] != "":
            constr_prefix = smtctop[1] + "."

    if smtcinit:
        steps_start = steps_stop - 1

    with open(filename, "w") as f:
        primary_inputs = list()

        for name in smt.modinfo[constr_topmod].inputs:
            width = smt.modinfo[constr_topmod].wsize[name]
            primary_inputs.append((name, width))

        if steps_start == 0 or smtcinit:
            print("initial", file=f)
        else:
            print("state %d" % steps_start, file=f)

        regnames = sorted(smt.hiernets(constr_topmod, regs_only=True))
        regvals = smt.get_net_list(constr_topmod, regnames, constr_state.replace("@@step_idx@@", str(steps_start)))

        for name, val in zip(regnames, regvals):
            print("assume (= [%s%s] %s)" % (constr_prefix, ".".join(name), val), file=f)

        mems = sorted(smt.hiermems(constr_topmod))
        for mempath in mems:
            abits, width, rports, wports, asyncwr = smt.mem_info(constr_topmod, mempath)

            addr_expr_list = list()
            data_expr_list = list()
            for i in range(steps_start, steps_stop):
                for j in range(rports):
                    addr_expr_list.append(smt.mem_expr(constr_topmod, constr_state.replace("@@step_idx@@", str(i)), mempath, "R%dA" % j))
                    data_expr_list.append(smt.mem_expr(constr_topmod, constr_state.replace("@@step_idx@@", str(i)), mempath, "R%dD" % j))

            addr_list = smt.get_list(addr_expr_list)
            data_list = smt.get_list(data_expr_list)

            addr_data = dict()
            for addr, data in zip(addr_list, data_list):
                if addr not in addr_data:
                    addr_data[addr] = data

            for addr, data in addr_data.items():
                print("assume (= (select [%s%s] %s) %s)" % (constr_prefix, ".".join(mempath), addr, data), file=f)

        for k in range(steps_start, steps_stop):
            if not smtcinit:
                print("", file=f)
                print("state %d" % k, file=f)

            pi_names = [[name] for name, _ in sorted(primary_inputs)]
            pi_values = smt.get_net_list(constr_topmod, pi_names, constr_state.replace("@@step_idx@@", str(k)))

            for name, val in zip(pi_names, pi_values):
                print("assume (= [%s%s] %s)" % (constr_prefix, ".".join(name), val), file=f)


def write_trace(steps_start, steps_stop, index):
    if vcdfile is not None:
        write_vcd_trace(steps_start, steps_stop, index)

    if vlogtbfile is not None:
        write_vlogtb_trace(steps_start, steps_stop, index)

    if outconstr is not None:
        write_constr_trace(steps_start, steps_stop, index)


def print_failed_asserts_worker(mod, state, path, extrainfo):
    assert mod in smt.modinfo
    found_failed_assert = False

    if smt.get("(|%s_a| %s)" % (mod, state)) in ["true", "#b1"]:
        return

    for cellname, celltype in smt.modinfo[mod].cells.items():
        if print_failed_asserts_worker(celltype, "(|%s_h %s| %s)" % (mod, cellname, state), path + "." + cellname, extrainfo):
            found_failed_assert = True

    for assertfun, assertinfo in smt.modinfo[mod].asserts.items():
        if smt.get("(|%s| %s)" % (assertfun, state)) in ["false", "#b0"]:
            print_msg("Assert failed in %s: %s%s" % (path, assertinfo, extrainfo))
            found_failed_assert = True

    return found_failed_assert


def print_failed_asserts(state, final=False, extrainfo=""):
    if noinfo: return
    loc_list, expr_list, value_list = get_constr_expr(constr_asserts, state, final=final, getvalues=True)
    found_failed_assert = False

    for loc, expr, value in zip(loc_list, expr_list, value_list):
        if smt.bv2int(value) == 0:
            print_msg("Assert %s failed: %s%s" % (loc, expr, extrainfo))
            found_failed_assert = True

    if not final:
        if print_failed_asserts_worker(topmod, "s%d" % state, topmod, extrainfo):
            found_failed_assert = True

    return found_failed_assert


def print_anyconsts_worker(mod, state, path):
    assert mod in smt.modinfo

    for cellname, celltype in smt.modinfo[mod].cells.items():
        print_anyconsts_worker(celltype, "(|%s_h %s| %s)" % (mod, cellname, state), path + "." + cellname)

    for fun, info in smt.modinfo[mod].anyconsts.items():
        if info[1] is None:
            if not binarymode:
                print_msg("Value for anyconst in %s (%s): %d" % (path, info[0], smt.bv2int(smt.get("(|%s| %s)" % (fun, state)))))
            else:
                print_msg("Value for anyconst in %s (%s): %s" % (path, info[0], smt.bv2bin(smt.get("(|%s| %s)" % (fun, state)))))
        else:
            if not binarymode:
                print_msg("Value for anyconst %s.%s (%s): %d" % (path, info[1], info[0], smt.bv2int(smt.get("(|%s| %s)" % (fun, state)))))
            else:
                print_msg("Value for anyconst %s.%s (%s): %s" % (path, info[1], info[0], smt.bv2bin(smt.get("(|%s| %s)" % (fun, state)))))


def print_anyconsts(state):
    if noinfo: return
    print_anyconsts_worker(topmod, "s%d" % state, topmod)


def get_cover_list(mod, base):
    assert mod in smt.modinfo

    cover_expr = list()
    cover_desc = list()

    for expr, desc in smt.modinfo[mod].covers.items():
        cover_expr.append("(ite (|%s| %s) #b1 #b0)" % (expr, base))
        cover_desc.append(desc)

    for cell, submod in smt.modinfo[mod].cells.items():
        e, d = get_cover_list(submod, "(|%s_h %s| %s)" % (mod, cell, base))
        cover_expr += e
        cover_desc += d

    return cover_expr, cover_desc

states = list()
asserts_antecedent_cache = [list()]
asserts_consequent_cache = [list()]
asserts_cache_dirty = False

def smt_state(step):
    smt.write("(declare-fun s%d () |%s_s|)" % (step, topmod))
    states.append("s%d" % step)

def smt_assert(expr):
    if expr == "true":
        return

    smt.write("(assert %s)" % expr)

def smt_assert_antecedent(expr):
    if expr == "true":
        return

    smt.write("(assert %s)" % expr)

    global asserts_cache_dirty
    asserts_cache_dirty = True
    asserts_antecedent_cache[-1].append(expr)

def smt_assert_consequent(expr):
    if expr == "true":
        return

    smt.write("(assert %s)" % expr)

    global asserts_cache_dirty
    asserts_cache_dirty = True
    asserts_consequent_cache[-1].append(expr)

def smt_forall_assert():
    if not smt.forall:
        return

    global asserts_cache_dirty
    asserts_cache_dirty = False

    assert (len(smt.modinfo[topmod].maximize) + len(smt.modinfo[topmod].minimize) <= 1)

    def make_assert_expr(asserts_cache):
        expr = list()
        for lst in asserts_cache:
            expr += lst

        assert len(expr) != 0

        if len(expr) == 1:
            expr = expr[0]
        else:
            expr = "(and %s)" % (" ".join(expr))
        return expr

    antecedent_expr = make_assert_expr(asserts_antecedent_cache)
    consequent_expr = make_assert_expr(asserts_consequent_cache)

    states_db = set(states)
    used_states_db = set()
    new_antecedent_expr = list()
    new_consequent_expr = list()
    assert_expr = list()

    def make_new_expr(new_expr, expr):
        cursor = 0
        while cursor < len(expr):
            l = 1
            if expr[cursor] in '|"':
                while cursor+l+1 < len(expr) and expr[cursor] != expr[cursor+l]:
                    l += 1
                l += 1
            elif expr[cursor] not in '() ':
                while cursor+l < len(expr) and expr[cursor+l] not in '|"() ':
                    l += 1

            word = expr[cursor:cursor+l]
            if word in states_db:
                used_states_db.add(word)
                word += "_"

            new_expr.append(word)
            cursor += l

    make_new_expr(new_antecedent_expr, antecedent_expr)
    make_new_expr(new_consequent_expr, consequent_expr)

    new_antecedent_expr = ["".join(new_antecedent_expr)]
    new_consequent_expr = ["".join(new_consequent_expr)]

    if states[0] in used_states_db:
        new_antecedent_expr.append("(|%s_ex_state_eq| %s %s_)" % (topmod, states[0], states[0]))
    for s in states:
        if s in used_states_db:
            new_antecedent_expr.append("(|%s_ex_input_eq| %s %s_)" % (topmod, s, s))

    if len(new_antecedent_expr) == 0:
        new_antecedent_expr = "true"
    elif len(new_antecedent_expr) == 1:
        new_antecedent_expr = new_antecedent_expr[0]
    else:
        new_antecedent_expr = "(and %s)" % (" ".join(new_antecedent_expr))

    if len(new_consequent_expr) == 0:
        new_consequent_expr = "true"
    elif len(new_consequent_expr) == 1:
        new_consequent_expr = new_consequent_expr[0]
    else:
        new_consequent_expr = "(and %s)" % (" ".join(new_consequent_expr))

    assert_expr.append("(assert (forall (")
    first_state = True
    for s in states:
        if s in used_states_db:
            assert_expr.append("%s(%s_ |%s_s|)" % ("" if first_state else " ", s, topmod))
            first_state = False
    assert_expr.append(") (=> %s %s)))" % (new_antecedent_expr, new_consequent_expr))

    smt.write("".join(assert_expr))

    if len(smt.modinfo[topmod].maximize) > 0:
        for s in states:
            if s in used_states_db:
                smt.write("(maximize (|%s| %s))\n" % (smt.modinfo[topmod].maximize.copy().pop(), s))
                break

    if len(smt.modinfo[topmod].minimize) > 0:
        for s in states:
            if s in used_states_db:
                smt.write("(minimize (|%s| %s))\n" % (smt.modinfo[topmod].minimize.copy().pop(), s))
                break

def smt_push():
    global asserts_cache_dirty
    asserts_cache_dirty = True
    asserts_antecedent_cache.append(list())
    asserts_consequent_cache.append(list())
    smt.write("(push 1)")

def smt_pop():
    global asserts_cache_dirty
    asserts_cache_dirty = True
    asserts_antecedent_cache.pop()
    asserts_consequent_cache.pop()
    smt.write("(pop 1)")

def smt_check_sat():
    if asserts_cache_dirty:
        smt_forall_assert()
    return smt.check_sat()

if tempind:
    retstatus = "FAILED"
    skip_counter = step_size
    for step in range(num_steps, -1, -1):
        if smt.forall:
            print_msg("Temporal induction not supported for exists-forall problems.")
            break

        smt_state(step)
        smt_assert_consequent("(|%s_u| s%d)" % (topmod, step))
        smt_assert_antecedent("(|%s_h| s%d)" % (topmod, step))
        smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, step))
        smt_assert_consequent(get_constr_expr(constr_assumes, step))

        if step == num_steps:
            smt_assert("(not (and (|%s_a| s%d) %s))" % (topmod, step, get_constr_expr(constr_asserts, step)))

        else:
            smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, step, step+1))
            smt_assert("(|%s_a| s%d)" % (topmod, step))
            smt_assert(get_constr_expr(constr_asserts, step))

        if step > num_steps-skip_steps:
            print_msg("Skipping induction in step %d.." % (step))
            continue

        skip_counter += 1
        if skip_counter < step_size:
            print_msg("Skipping induction in step %d.." % (step))
            continue

        skip_counter = 0
        print_msg("Trying induction in step %d.." % (step))

        if smt_check_sat() == "sat":
            if step == 0:
                print_msg("Temporal induction failed!")
                print_anyconsts(num_steps)
                print_failed_asserts(num_steps)
                write_trace(step, num_steps+1, '%')

            elif dumpall:
                print_anyconsts(num_steps)
                print_failed_asserts(num_steps)
                write_trace(step, num_steps+1, "%d" % step)

        else:
            print_msg("Temporal induction successful.")
            retstatus = "PASSED"
            break

elif covermode:
    cover_expr, cover_desc = get_cover_list(topmod, "state")
    cover_mask = "1" * len(cover_desc)

    if len(cover_expr) > 1:
        cover_expr = "(concat %s)" % " ".join(cover_expr)
    elif len(cover_expr) == 1:
        cover_expr = cover_expr[0]
    else:
        cover_expr = "#b0"

    coveridx = 0
    smt.write("(define-fun covers_0 ((state |%s_s|)) (_ BitVec %d) %s)" % (topmod, len(cover_desc), cover_expr))

    step = 0
    retstatus = "FAILED"
    found_failed_assert = False

    assert step_size == 1

    while step < num_steps:
        smt_state(step)
        smt_assert_consequent("(|%s_u| s%d)" % (topmod, step))
        smt_assert_antecedent("(|%s_h| s%d)" % (topmod, step))
        smt_assert_consequent(get_constr_expr(constr_assumes, step))

        if step == 0:
            if noinit:
                smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, step))
            else:
                smt_assert_antecedent("(|%s_i| s0)" % (topmod))
                smt_assert_antecedent("(|%s_is| s0)" % (topmod))

        else:
            smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, step-1, step))
            smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, step))

        while "1" in cover_mask:
            print_msg("Checking cover reachability in step %d.." % (step))
            smt_push()
            smt_assert("(distinct (covers_%d s%d) #b%s)" % (coveridx, step, "0" * len(cover_desc)))

            if smt_check_sat() == "unsat":
                smt_pop()
                break

            if append_steps > 0:
                for i in range(step+1, step+1+append_steps):
                    print_msg("Appending additional step %d." % i)
                    smt_state(i)
                    smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, i))
                    smt_assert_consequent("(|%s_u| s%d)" % (topmod, i))
                    smt_assert_antecedent("(|%s_h| s%d)" % (topmod, i))
                    smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, i-1, i))
                    smt_assert_consequent(get_constr_expr(constr_assumes, i))
                print_msg("Re-solving with appended steps..")
                if smt_check_sat() == "unsat":
                    print("%s Cannot appended steps without violating assumptions!" % smt.timestamp())
                    found_failed_assert = True
                    retstatus = "FAILED"
                    break

            reached_covers = smt.bv2bin(smt.get("(covers_%d s%d)" % (coveridx, step)))
            assert len(reached_covers) == len(cover_desc)

            new_cover_mask = []

            for i in range(len(reached_covers)):
                if reached_covers[i] == "0":
                    new_cover_mask.append(cover_mask[i])
                    continue

                print_msg("Reached cover statement at %s in step %d." % (cover_desc[i], step))
                new_cover_mask.append("0")

            cover_mask = "".join(new_cover_mask)

            for i in range(step+1+append_steps):
                if print_failed_asserts(i, extrainfo=" (step %d)" % i):
                    found_failed_assert = True

            write_trace(0, step+1+append_steps, "%d" % coveridx)

            if found_failed_assert:
                break

            coveridx += 1
            smt_pop()
            smt.write("(define-fun covers_%d ((state |%s_s|)) (_ BitVec %d) (bvand (covers_%d state) #b%s))" % (coveridx, topmod, len(cover_desc), coveridx-1, cover_mask))

        if found_failed_assert:
            break

        if "1" not in cover_mask:
            retstatus = "PASSED"
            break

        step += 1

    if "1" in cover_mask:
        for i in range(len(cover_mask)):
            if cover_mask[i] == "1":
                print_msg("Unreached cover statement at %s." % cover_desc[i])

else:  # not tempind, covermode
    step = 0
    retstatus = "PASSED"
    while step < num_steps:
        smt_state(step)
        smt_assert_consequent("(|%s_u| s%d)" % (topmod, step))
        smt_assert_antecedent("(|%s_h| s%d)" % (topmod, step))
        smt_assert_consequent(get_constr_expr(constr_assumes, step))

        if step == 0:
            if noinit:
                smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, step))
            else:
                smt_assert_antecedent("(|%s_i| s0)" % (topmod))
                smt_assert_antecedent("(|%s_is| s0)" % (topmod))

        else:
            smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, step-1, step))
            smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, step))

        if step < skip_steps:
            if assume_skipped is not None and step >= assume_skipped:
                print_msg("Skipping step %d (and assuming pass).." % (step))
                smt_assert("(|%s_a| s%d)" % (topmod, step))
                smt_assert(get_constr_expr(constr_asserts, step))
            else:
                print_msg("Skipping step %d.." % (step))
            step += 1
            continue

        last_check_step = step
        for i in range(1, step_size):
            if step+i < num_steps:
                smt_state(step+i)
                smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, step+i))
                smt_assert_consequent("(|%s_u| s%d)" % (topmod, step+i))
                smt_assert_antecedent("(|%s_h| s%d)" % (topmod, step+i))
                smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, step+i-1, step+i))
                smt_assert_consequent(get_constr_expr(constr_assumes, step+i))
                last_check_step = step+i

        if not gentrace:
            if presat:
                if last_check_step == step:
                    print_msg("Checking assumptions in step %d.." % (step))
                else:
                    print_msg("Checking assumptions in steps %d to %d.." % (step, last_check_step))

                if smt_check_sat() == "unsat":
                    print("%s Assumptions are unsatisfiable!" % smt.timestamp())
                    retstatus = "PREUNSAT"
                    break

            if not final_only:
                if last_check_step == step:
                    print_msg("Checking assertions in step %d.." % (step))
                else:
                    print_msg("Checking assertions in steps %d to %d.." % (step, last_check_step))
                smt_push()

                smt_assert("(not (and %s))" % " ".join(["(|%s_a| s%d)" % (topmod, i) for i in range(step, last_check_step+1)] +
                        [get_constr_expr(constr_asserts, i) for i in range(step, last_check_step+1)]))

                if smt_check_sat() == "sat":
                    print("%s BMC failed!" % smt.timestamp())
                    if append_steps > 0:
                        for i in range(last_check_step+1, last_check_step+1+append_steps):
                            print_msg("Appending additional step %d." % i)
                            smt_state(i)
                            smt_assert_antecedent("(not (|%s_is| s%d))" % (topmod, i))
                            smt_assert_consequent("(|%s_u| s%d)" % (topmod, i))
                            smt_assert_antecedent("(|%s_h| s%d)" % (topmod, i))
                            smt_assert_antecedent("(|%s_t| s%d s%d)" % (topmod, i-1, i))
                            smt_assert_consequent(get_constr_expr(constr_assumes, i))
                        print_msg("Re-solving with appended steps..")
                        if smt_check_sat() == "unsat":
                            print("%s Cannot append steps without violating assumptions!" % smt.timestamp())
                            retstatus = "FAILED"
                            break
                    print_anyconsts(step)
                    for i in range(step, last_check_step+1):
                        print_failed_asserts(i)
                    write_trace(0, last_check_step+1+append_steps, '%')
                    retstatus = "FAILED"
                    break

                smt_pop()

            if (constr_final_start is not None) or (last_check_step+1 != num_steps):
                for i in range(step, last_check_step+1):
                    smt_assert("(|%s_a| s%d)" % (topmod, i))
                    smt_assert(get_constr_expr(constr_asserts, i))

            if constr_final_start is not None:
                for i in range(step, last_check_step+1):
                    if i < constr_final_start:
                        continue

                    print_msg("Checking final constraints in step %d.." % (i))
                    smt_push()

                    smt_assert_consequent(get_constr_expr(constr_assumes, i, final=True))
                    smt_assert("(not %s)" % get_constr_expr(constr_asserts, i, final=True))

                    if smt_check_sat() == "sat":
                        print("%s BMC failed!" % smt.timestamp())
                        print_anyconsts(i)
                        print_failed_asserts(i, final=True)
                        write_trace(0, i+1, '%')
                        retstatus = "FAILED"
                        break

                    smt_pop()
                if retstatus == "FAILED" or retstatus == "PREUNSAT":
                    break

        else:  # gentrace
            for i in range(step, last_check_step+1):
                smt_assert("(|%s_a| s%d)" % (topmod, i))
                smt_assert(get_constr_expr(constr_asserts, i))

            print_msg("Solving for step %d.." % (last_check_step))
            status = smt_check_sat()
            if status != "sat":
                print("%s No solution found! (%s)" % (smt.timestamp(), status))
                retstatus = "FAILED"
                break

            elif dumpall:
                print_anyconsts(0)
                write_trace(0, last_check_step+1, "%d" % step)

        step += step_size

    if gentrace and retstatus == "PASSED":
        print_anyconsts(0)
        write_trace(0, num_steps, '%')


smt.write("(exit)")
smt.wait()

print_msg("Status: %s" % retstatus)
sys.exit(0 if retstatus == "PASSED" else 1)