423 lines
12 KiB
C++
423 lines
12 KiB
C++
// OpenSTA, Static Timing Analyzer
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// Copyright (c) 2025, Parallax Software, Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//
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// The origin of this software must not be misrepresented; you must not
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// claim that you wrote the original software.
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//
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// Altered source versions must be plainly marked as such, and must not be
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// misrepresented as being the original software.
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//
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// This notice may not be removed or altered from any source distribution.
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#include "CheckSlewLimits.hh"
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#include "Fuzzy.hh"
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#include "Liberty.hh"
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#include "Network.hh"
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#include "Sdc.hh"
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#include "InputDrive.hh"
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#include "Graph.hh"
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#include "DcalcAnalysisPt.hh"
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#include "GraphDelayCalc.hh"
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#include "StaState.hh"
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#include "Corner.hh"
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#include "Path.hh"
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#include "PortDirection.hh"
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#include "Search.hh"
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#include "ClkNetwork.hh"
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namespace sta {
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class PinSlewLimitSlackLess
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{
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public:
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PinSlewLimitSlackLess(const Corner *corner,
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const MinMax *min_max,
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CheckSlewLimits *check_slew_limit,
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const StaState *sta);
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bool operator()(const Pin *pin1,
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const Pin *pin2) const;
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private:
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const Corner *corner_;
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const MinMax *min_max_;
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CheckSlewLimits *check_slew_limit_;
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const StaState *sta_;
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};
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PinSlewLimitSlackLess::PinSlewLimitSlackLess(const Corner *corner,
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const MinMax *min_max,
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CheckSlewLimits *check_slew_limit,
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const StaState *sta) :
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corner_(corner),
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min_max_(min_max),
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check_slew_limit_(check_slew_limit),
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sta_(sta)
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{
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}
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bool
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PinSlewLimitSlackLess::operator()(const Pin *pin1,
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const Pin *pin2) const
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{
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const Corner *corner1, *corner2;
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const RiseFall *rf1, *rf2;
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Slew slew1, slew2;
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float limit1, limit2, slack1, slack2;
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check_slew_limit_->checkSlew(pin1, corner_, min_max_, true,
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corner1, rf1, slew1, limit1, slack1);
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check_slew_limit_->checkSlew(pin2, corner_, min_max_, true,
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corner2, rf2, slew2, limit2, slack2);
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return fuzzyLess(slack1, slack2)
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|| (fuzzyEqual(slack1, slack2)
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// Break ties for the sake of regression stability.
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&& sta_->network()->pinLess(pin1, pin2));
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}
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////////////////////////////////////////////////////////////////
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CheckSlewLimits::CheckSlewLimits(const StaState *sta) :
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sta_(sta)
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{
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}
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void
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CheckSlewLimits::checkSlewLimits(const Pin *pin,
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bool violators,
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const Corner *corner,
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const MinMax *min_max,
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PinSeq &slew_pins,
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float &min_slack)
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{
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const Corner *corner1;
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const RiseFall *rf;
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Slew slew;
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float limit, slack;
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checkSlew(pin, corner, min_max, true, corner1, rf, slew, limit, slack);
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if (!fuzzyInf(slack)) {
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if (violators) {
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if (slack < 0.0)
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slew_pins.push_back(pin);
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}
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else {
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if (slew_pins.empty()
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|| slack < min_slack) {
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slew_pins.push_back(pin);
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min_slack = slack;
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}
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}
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}
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}
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void
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CheckSlewLimits::checkSlew(const Pin *pin,
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const Corner *corner,
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const MinMax *min_max,
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bool check_clks,
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// Return values.
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const Corner *&corner1,
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const RiseFall *&rf1,
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Slew &slew1,
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float &limit1,
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float &slack1) const
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{
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corner1 = nullptr;
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rf1 = nullptr;
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slew1 = 0.0;
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limit1 = 0.0;
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slack1 = MinMax::min()->initValue();
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Vertex *vertex, *bidirect_drvr_vertex;
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sta_->graph()->pinVertices(pin, vertex, bidirect_drvr_vertex);
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if (vertex)
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checkSlew1(pin, vertex, corner, min_max, check_clks,
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corner1, rf1, slew1, limit1, slack1);
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if (bidirect_drvr_vertex)
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checkSlew1(pin, bidirect_drvr_vertex, corner, min_max, check_clks,
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corner1, rf1, slew1, limit1, slack1);
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}
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void
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CheckSlewLimits::checkSlew1(const Pin *pin,
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const Vertex *vertex,
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const Corner *corner,
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const MinMax *min_max,
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bool check_clks,
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// Return values.
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const Corner *&corner1,
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const RiseFall *&rf1,
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Slew &slew1,
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float &limit1,
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float &slack1) const
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{
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if (!vertex->isDisabledConstraint()
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&& !vertex->isConstant()
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&& !sta_->clkNetwork()->isIdealClock(pin)) {
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ClockSet clks;
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if (check_clks)
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clks = clockDomains(vertex);
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if (corner)
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checkSlew2(pin, vertex, corner, min_max, clks,
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corner1, rf1, slew1, limit1, slack1);
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else {
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for (auto corner : *sta_->corners()) {
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checkSlew2(pin, vertex, corner, min_max, clks,
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corner1, rf1, slew1, limit1, slack1);
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}
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}
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}
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}
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void
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CheckSlewLimits::checkSlew2(const Pin *pin,
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const Vertex *vertex,
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const Corner *corner,
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const MinMax *min_max,
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const ClockSet &clks,
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// Return values.
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const Corner *&corner1,
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const RiseFall *&rf1,
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Slew &slew1,
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float &limit1,
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float &slack1) const
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{
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for (const RiseFall *rf : RiseFall::range()) {
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float limit;
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bool exists;
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findLimit(pin, corner, rf, min_max, clks,
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limit, exists);
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if (exists) {
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checkSlew3(vertex, corner, rf, min_max, limit,
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corner1, rf1, slew1, slack1, limit1);
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}
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}
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}
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void
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CheckSlewLimits::checkSlew3(const Vertex *vertex,
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const Corner *corner,
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const RiseFall *rf,
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const MinMax *min_max,
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float limit,
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// Return values.
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const Corner *&corner1,
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const RiseFall *&rf1,
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Slew &slew1,
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float &slack1,
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float &limit1) const
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{
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const DcalcAnalysisPt *dcalc_ap = corner->findDcalcAnalysisPt(min_max);
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Slew slew = sta_->graph()->slew(vertex, rf, dcalc_ap->index());
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float slew2 = delayAsFloat(slew);
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float slack = (min_max == MinMax::max())
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? limit - slew2 : slew2 - limit;
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if (corner1 == nullptr
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|| (slack < slack1
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// Break ties for the sake of regression stability.
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|| (fuzzyEqual(slack, slack1)
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&& rf->index() < rf1->index()))) {
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corner1 = corner;
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rf1 = rf;
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slew1 = slew;
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slack1 = slack;
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limit1 = limit;
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}
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}
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// Return the tightest limit.
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void
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CheckSlewLimits::findLimit(const Pin *pin,
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const Corner *corner,
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const RiseFall *rf,
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const MinMax *min_max,
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const ClockSet &clks,
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// Return values.
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float &limit,
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bool &exists) const
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{
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const Network *network = sta_->network();
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Sdc *sdc = sta_->sdc();
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LibertyPort *port = network->libertyPort(pin);
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findLimit(port, corner, min_max,
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limit, exists);
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float limit1;
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bool exists1;
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if (!clks.empty()) {
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// Look for clock slew limits.
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bool is_clk = sta_->clkNetwork()->isIdealClock(pin);
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for (Clock *clk : clks) {
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PathClkOrData clk_data = is_clk ? PathClkOrData::clk : PathClkOrData::data;
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sdc->slewLimit(clk, rf, clk_data, min_max,
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limit1, exists1);
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if (exists1
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&& (!exists
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|| min_max->compare(limit, limit1))) {
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limit = limit1;
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exists = true;
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}
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}
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}
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if (network->isTopLevelPort(pin)) {
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Port *port = network->port(pin);
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sdc->slewLimit(port, min_max, limit1, exists1);
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if (exists1
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&& (!exists
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|| min_max->compare(limit, limit1))) {
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limit = limit1;
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exists = true;
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}
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InputDrive *drive = sdc->findInputDrive(port);
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if (drive) {
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for (auto rf : RiseFall::range()) {
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const LibertyCell *cell;
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const LibertyPort *from_port;
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float *from_slews;
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const LibertyPort *to_port;
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drive->driveCell(rf, min_max, cell, from_port, from_slews, to_port);
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if (to_port) {
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const LibertyPort *corner_port = to_port->cornerPort(corner, min_max);
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corner_port->slewLimit(min_max, limit1, exists1);
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if (!exists1
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&& corner_port->direction()->isAnyOutput()
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&& min_max == MinMax::max())
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corner_port->libertyLibrary()->defaultMaxSlew(limit1, exists1);
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if (exists1
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&& (!exists
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|| min_max->compare(limit, limit1))) {
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limit = limit1;
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exists = true;
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}
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}
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}
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}
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}
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}
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void
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CheckSlewLimits::findLimit(const LibertyPort *port,
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const Corner *corner,
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const MinMax *min_max,
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// Return values.
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float &limit,
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bool &exists) const
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{
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limit = INF;
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exists = false;
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const Network *network = sta_->network();
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Sdc *sdc = sta_->sdc();
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float limit1;
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bool exists1;
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// Default to top ("design") limit.
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Cell *top_cell = network->cell(network->topInstance());
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sdc->slewLimit(top_cell, min_max,
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limit1, exists1);
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if (exists1) {
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limit = limit1;
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exists = true;
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}
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if (port) {
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const LibertyPort *corner_port = port->cornerPort(corner, min_max);
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corner_port->slewLimit(min_max, limit1, exists1);
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if (!exists1
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// default_max_transition only applies to outputs.
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&& corner_port->direction()->isAnyOutput()
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&& min_max == MinMax::max())
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corner_port->libertyLibrary()->defaultMaxSlew(limit1, exists1);
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if (exists1
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&& (!exists
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|| min_max->compare(limit, limit1))) {
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limit = limit1;
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exists = true;
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}
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}
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}
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ClockSet
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CheckSlewLimits::clockDomains(const Vertex *vertex) const
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{
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ClockSet clks;
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VertexPathIterator path_iter(const_cast<Vertex*>(vertex), sta_);
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while (path_iter.hasNext()) {
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Path *path = path_iter.next();
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const Clock *clk = path->clock(sta_);
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if (clk)
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clks.insert(const_cast<Clock*>(clk));
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}
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return clks;
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}
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////////////////////////////////////////////////////////////////
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PinSeq
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CheckSlewLimits::checkSlewLimits(const Net *net,
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bool violators,
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const Corner *corner,
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const MinMax *min_max)
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{
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const Network *network = sta_->network();
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PinSeq slew_pins;
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float min_slack = MinMax::min()->initValue();
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if (net) {
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NetPinIterator *pin_iter = network->pinIterator(net);
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while (pin_iter->hasNext()) {
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const Pin *pin = pin_iter->next();
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checkSlewLimits(pin, violators, corner, min_max, slew_pins, min_slack);
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}
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delete pin_iter;
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}
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else {
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LeafInstanceIterator *inst_iter = network->leafInstanceIterator();
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while (inst_iter->hasNext()) {
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const Instance *inst = inst_iter->next();
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checkSlewLimits(inst, violators,corner, min_max, slew_pins, min_slack);
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}
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delete inst_iter;
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// Check top level ports.
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checkSlewLimits(network->topInstance(), violators, corner, min_max,
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slew_pins, min_slack);
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}
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sort(slew_pins, PinSlewLimitSlackLess(corner, min_max, this, sta_));
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// Keep the min slack pin unless all violators or net pins.
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if (!slew_pins.empty() && !violators && net == nullptr)
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slew_pins.resize(1);
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return slew_pins;
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}
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void
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CheckSlewLimits::checkSlewLimits(const Instance *inst,
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bool violators,
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const Corner *corner,
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const MinMax *min_max,
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PinSeq &slew_pins,
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float &min_slack)
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{
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const Network *network = sta_->network();
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InstancePinIterator *pin_iter = network->pinIterator(inst);
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while (pin_iter->hasNext()) {
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Pin *pin = pin_iter->next();
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checkSlewLimits(pin, violators, corner, min_max, slew_pins, min_slack);
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}
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delete pin_iter;
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}
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} // namespace
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