yosys/kernel/qcsat.h

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/* -*- c++ -*-
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2021 Marcelina Kościelnicka <mwk@0x04.net>
*
* 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.
*
*/
#ifndef QCSAT_H
#define QCSAT_H
#include "kernel/satgen.h"
#include "kernel/modtools.h"
YOSYS_NAMESPACE_BEGIN
// This is a helper class meant for easy construction of quick SAT queries
// to a combinatorial input cone of some set of signals, meant for SAT-based
// optimizations. Various knobs are provided to set just how much of the
// cone should be included in the model — since this class is meant for
// optimization, it should not be a correctness problem when some cells are
// skipped and the solver spuriously returns SAT with a solution that
// cannot exist in reality due to skipped constraints (ie. only UNSAT results
// from this class should be considered binding).
struct QuickConeSat {
ModWalker &modwalker;
ezSatPtr ez;
SatGen satgen;
// The effort level knobs.
// The maximum "complexity level" of cells that will be imported.
// - 1: bitwise operations, muxes, equality comparisons, lut, sop, fa
// - 2: addition, subtraction, greater/less than comparisons, lcu
// - 3: shifts
// - 4: multiplication, division, power
int max_cell_complexity = 2;
// The maximum number of cells to import, or 0 for no limit.
int max_cell_count = 0;
// If non-0, skip importing cells with more than this number of output bits.
int max_cell_outs = 0;
// Internal state.
pool<RTLIL::Cell*> imported_cells;
pool<RTLIL::Wire*> imported_onehot;
pool<RTLIL::SigBit> bits_queue;
QuickConeSat(ModWalker &modwalker) : modwalker(modwalker), ez(), satgen(ez.get(), &modwalker.sigmap) {}
// Imports a signal into the SAT solver, queues its input cone to be
// imported in the next prepare() call.
std::vector<int> importSig(SigSpec sig);
int importSigBit(SigBit bit);
// Imports the input cones of all previously importSig'd signals into
// the SAT solver.
void prepare();
// Returns the "complexity level" of a given cell.
static int cell_complexity(RTLIL::Cell *cell);
};
YOSYS_NAMESPACE_END
#endif