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d25b9088c8
This also aligns the functionality: - in all cases, the onehot attribute is used to create appropriate constraints (previously, opt_dff didn't do it at all, and share created one-hot constraints based on $pmux presence alone, which is unsound) - in all cases, shift and mul/div/pow cells are now skipped when importing the SAT problem (previously only memory_share did this) — this avoids creating clauses for hard cells that are unlikely to help with proving the UNSATness needed for optimization
76 lines
2.7 KiB
C++
76 lines
2.7 KiB
C++
/* -*- c++ -*-
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* yosys -- Yosys Open SYnthesis Suite
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*
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* Copyright (C) 2021 Marcelina Kościelnicka <mwk@0x04.net>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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*/
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#ifndef QCSAT_H
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#define QCSAT_H
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#include "kernel/satgen.h"
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#include "kernel/modtools.h"
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YOSYS_NAMESPACE_BEGIN
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// This is a helper class meant for easy construction of quick SAT queries
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// to a combinatorial input cone of some set of signals, meant for SAT-based
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// optimizations. Various knobs are provided to set just how much of the
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// cone should be included in the model — since this class is meant for
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// optimization, it should not be a correctness problem when some cells are
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// skipped and the solver spuriously returns SAT with a solution that
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// cannot exist in reality due to skipped constraints (ie. only UNSAT results
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// from this class should be considered binding).
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struct QuickConeSat {
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ModWalker &modwalker;
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ezSatPtr ez;
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SatGen satgen;
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// The effort level knobs.
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// The maximum "complexity level" of cells that will be imported.
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// - 1: bitwise operations, muxes, equality comparisons, lut, sop, fa
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// - 2: addition, subtraction, greater/less than comparisons, lcu
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// - 3: shifts
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// - 4: multiplication, division, power
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int max_cell_complexity = 2;
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// The maximum number of cells to import, or 0 for no limit.
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int max_cell_count = 0;
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// If non-0, skip importing cells with more than this number of output bits.
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int max_cell_outs = 0;
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// Internal state.
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pool<RTLIL::Cell*> imported_cells;
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pool<RTLIL::Wire*> imported_onehot;
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pool<RTLIL::SigBit> bits_queue;
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QuickConeSat(ModWalker &modwalker) : modwalker(modwalker), ez(), satgen(ez.get(), &modwalker.sigmap) {}
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// Imports a signal into the SAT solver, queues its input cone to be
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// imported in the next prepare() call.
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std::vector<int> importSig(SigSpec sig);
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int importSigBit(SigBit bit);
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// Imports the input cones of all previously importSig'd signals into
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// the SAT solver.
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void prepare();
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// Returns the "complexity level" of a given cell.
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static int cell_complexity(RTLIL::Cell *cell);
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};
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YOSYS_NAMESPACE_END
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#endif
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