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computation code. Also, avoid adding output-depenency edges when both defs are dead, which frequently happens with EFLAGS defs. Compute Depth and Height lazily, and always in terms of edge latency values. For the schedulers that don't care about latency, edge latencies are set to 1. Eliminate Cycle and CycleBound, and LatencyPriorityQueue's Latencies array. These are all subsumed by the Depth and Height fields. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61073 91177308-0d34-0410-b5e6-96231b3b80d8
552 lines
16 KiB
C++
552 lines
16 KiB
C++
//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This implements the ScheduleDAG class, which is a base class used by
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// scheduling implementation classes.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "pre-RA-sched"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Support/Debug.h"
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#include <climits>
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using namespace llvm;
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ScheduleDAG::ScheduleDAG(SelectionDAG *dag, MachineBasicBlock *bb,
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const TargetMachine &tm)
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: DAG(dag), BB(bb), TM(tm), MRI(BB->getParent()->getRegInfo()) {
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TII = TM.getInstrInfo();
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MF = BB->getParent();
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TRI = TM.getRegisterInfo();
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TLI = TM.getTargetLowering();
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ConstPool = MF->getConstantPool();
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}
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ScheduleDAG::~ScheduleDAG() {}
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/// dump - dump the schedule.
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void ScheduleDAG::dumpSchedule() const {
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for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
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if (SUnit *SU = Sequence[i])
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SU->dump(this);
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else
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cerr << "**** NOOP ****\n";
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}
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}
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/// Run - perform scheduling.
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///
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void ScheduleDAG::Run() {
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Schedule();
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DOUT << "*** Final schedule ***\n";
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DEBUG(dumpSchedule());
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DOUT << "\n";
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}
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/// addPred - This adds the specified edge as a pred of the current node if
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/// not already. It also adds the current node as a successor of the
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/// specified node.
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void SUnit::addPred(const SDep &D) {
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// If this node already has this depenence, don't add a redundant one.
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for (unsigned i = 0, e = (unsigned)Preds.size(); i != e; ++i)
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if (Preds[i] == D)
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return;
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// Now add a corresponding succ to N.
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SDep P = D;
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P.setSUnit(this);
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SUnit *N = D.getSUnit();
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// Update the bookkeeping.
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if (D.getKind() == SDep::Data) {
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++NumPreds;
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++N->NumSuccs;
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}
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if (!N->isScheduled)
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++NumPredsLeft;
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if (!isScheduled)
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++N->NumSuccsLeft;
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N->Succs.push_back(P);
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Preds.push_back(D);
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this->setDepthDirty();
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N->setHeightDirty();
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}
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/// removePred - This removes the specified edge as a pred of the current
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/// node if it exists. It also removes the current node as a successor of
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/// the specified node.
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void SUnit::removePred(const SDep &D) {
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// Find the matching predecessor.
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for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
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I != E; ++I)
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if (*I == D) {
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bool FoundSucc = false;
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// Find the corresponding successor in N.
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SDep P = D;
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P.setSUnit(this);
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SUnit *N = D.getSUnit();
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for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(),
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EE = N->Succs.end(); II != EE; ++II)
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if (*II == P) {
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FoundSucc = true;
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N->Succs.erase(II);
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break;
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}
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assert(FoundSucc && "Mismatching preds / succs lists!");
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Preds.erase(I);
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// Update the bookkeeping;
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if (D.getKind() == SDep::Data) {
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--NumPreds;
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--N->NumSuccs;
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}
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if (!N->isScheduled)
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--NumPredsLeft;
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if (!isScheduled)
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--N->NumSuccsLeft;
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this->setDepthDirty();
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N->setHeightDirty();
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return;
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}
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}
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void SUnit::setDepthDirty() {
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SmallVector<SUnit*, 8> WorkList;
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WorkList.push_back(this);
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while (!WorkList.empty()) {
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SUnit *SU = WorkList.back();
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WorkList.pop_back();
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if (!SU->isDepthCurrent) continue;
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SU->isDepthCurrent = false;
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for (SUnit::const_succ_iterator I = Succs.begin(),
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E = Succs.end(); I != E; ++I)
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WorkList.push_back(I->getSUnit());
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}
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}
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void SUnit::setHeightDirty() {
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SmallVector<SUnit*, 8> WorkList;
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WorkList.push_back(this);
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while (!WorkList.empty()) {
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SUnit *SU = WorkList.back();
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WorkList.pop_back();
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if (!SU->isHeightCurrent) continue;
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SU->isHeightCurrent = false;
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for (SUnit::const_pred_iterator I = Preds.begin(),
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E = Preds.end(); I != E; ++I)
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WorkList.push_back(I->getSUnit());
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}
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}
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/// setDepthToAtLeast - Update this node's successors to reflect the
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/// fact that this node's depth just increased.
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///
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void SUnit::setDepthToAtLeast(unsigned NewDepth) {
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if (NewDepth <= Depth)
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return;
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setDepthDirty();
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Depth = NewDepth;
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isDepthCurrent = true;
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}
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/// setHeightToAtLeast - Update this node's predecessors to reflect the
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/// fact that this node's height just increased.
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///
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void SUnit::setHeightToAtLeast(unsigned NewHeight) {
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if (NewHeight <= Height)
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return;
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setHeightDirty();
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Height = NewHeight;
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isHeightCurrent = true;
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}
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/// ComputeDepth - Calculate the maximal path from the node to the exit.
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///
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void SUnit::ComputeDepth() {
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SmallVector<SUnit*, 8> WorkList;
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WorkList.push_back(this);
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while (!WorkList.empty()) {
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SUnit *Cur = WorkList.back();
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bool Done = true;
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unsigned MaxPredDepth = 0;
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for (SUnit::const_pred_iterator I = Cur->Preds.begin(),
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E = Cur->Preds.end(); I != E; ++I) {
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SUnit *PredSU = I->getSUnit();
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if (PredSU->isDepthCurrent)
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MaxPredDepth = std::max(MaxPredDepth,
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PredSU->Depth + I->getLatency());
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else {
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Done = false;
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WorkList.push_back(PredSU);
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}
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}
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if (Done) {
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WorkList.pop_back();
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if (MaxPredDepth != Cur->Depth) {
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Cur->setDepthDirty();
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Cur->Depth = MaxPredDepth;
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}
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Cur->isDepthCurrent = true;
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}
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}
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}
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/// ComputeHeight - Calculate the maximal path from the node to the entry.
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///
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void SUnit::ComputeHeight() {
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SmallVector<SUnit*, 8> WorkList;
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WorkList.push_back(this);
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while (!WorkList.empty()) {
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SUnit *Cur = WorkList.back();
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bool Done = true;
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unsigned MaxSuccHeight = 0;
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for (SUnit::const_succ_iterator I = Cur->Succs.begin(),
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E = Cur->Succs.end(); I != E; ++I) {
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SUnit *SuccSU = I->getSUnit();
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if (SuccSU->isHeightCurrent)
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MaxSuccHeight = std::max(MaxSuccHeight,
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SuccSU->Height + I->getLatency());
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else {
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Done = false;
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WorkList.push_back(SuccSU);
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}
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}
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if (Done) {
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WorkList.pop_back();
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if (MaxSuccHeight != Cur->Height) {
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Cur->setHeightDirty();
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Cur->Height = MaxSuccHeight;
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}
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Cur->isHeightCurrent = true;
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}
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}
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}
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/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
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/// a group of nodes flagged together.
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void SUnit::dump(const ScheduleDAG *G) const {
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cerr << "SU(" << NodeNum << "): ";
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G->dumpNode(this);
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}
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void SUnit::dumpAll(const ScheduleDAG *G) const {
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dump(G);
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cerr << " # preds left : " << NumPredsLeft << "\n";
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cerr << " # succs left : " << NumSuccsLeft << "\n";
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cerr << " Latency : " << Latency << "\n";
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cerr << " Depth : " << Depth << "\n";
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cerr << " Height : " << Height << "\n";
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if (Preds.size() != 0) {
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cerr << " Predecessors:\n";
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for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
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I != E; ++I) {
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cerr << " ";
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switch (I->getKind()) {
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case SDep::Data: cerr << "val "; break;
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case SDep::Anti: cerr << "anti"; break;
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case SDep::Output: cerr << "out "; break;
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case SDep::Order: cerr << "ch "; break;
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}
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cerr << "#";
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cerr << I->getSUnit() << " - SU(" << I->getSUnit()->NodeNum << ")";
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if (I->isArtificial())
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cerr << " *";
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cerr << "\n";
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}
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}
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if (Succs.size() != 0) {
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cerr << " Successors:\n";
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for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
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I != E; ++I) {
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cerr << " ";
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switch (I->getKind()) {
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case SDep::Data: cerr << "val "; break;
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case SDep::Anti: cerr << "anti"; break;
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case SDep::Output: cerr << "out "; break;
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case SDep::Order: cerr << "ch "; break;
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}
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cerr << "#";
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cerr << I->getSUnit() << " - SU(" << I->getSUnit()->NodeNum << ")";
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if (I->isArtificial())
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cerr << " *";
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cerr << "\n";
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}
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}
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cerr << "\n";
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}
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#ifndef NDEBUG
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/// VerifySchedule - Verify that all SUnits were scheduled and that
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/// their state is consistent.
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///
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void ScheduleDAG::VerifySchedule(bool isBottomUp) {
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bool AnyNotSched = false;
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unsigned DeadNodes = 0;
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unsigned Noops = 0;
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for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
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if (!SUnits[i].isScheduled) {
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if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
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++DeadNodes;
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continue;
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}
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if (!AnyNotSched)
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cerr << "*** Scheduling failed! ***\n";
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SUnits[i].dump(this);
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cerr << "has not been scheduled!\n";
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AnyNotSched = true;
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}
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if (SUnits[i].isScheduled &&
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(isBottomUp ? SUnits[i].getHeight() : SUnits[i].getHeight()) >
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unsigned(INT_MAX)) {
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if (!AnyNotSched)
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cerr << "*** Scheduling failed! ***\n";
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SUnits[i].dump(this);
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cerr << "has an unexpected "
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<< (isBottomUp ? "Height" : "Depth") << " value!\n";
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AnyNotSched = true;
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}
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if (isBottomUp) {
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if (SUnits[i].NumSuccsLeft != 0) {
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if (!AnyNotSched)
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cerr << "*** Scheduling failed! ***\n";
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SUnits[i].dump(this);
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cerr << "has successors left!\n";
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AnyNotSched = true;
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}
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} else {
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if (SUnits[i].NumPredsLeft != 0) {
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if (!AnyNotSched)
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cerr << "*** Scheduling failed! ***\n";
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SUnits[i].dump(this);
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cerr << "has predecessors left!\n";
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AnyNotSched = true;
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}
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}
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}
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for (unsigned i = 0, e = Sequence.size(); i != e; ++i)
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if (!Sequence[i])
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++Noops;
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assert(!AnyNotSched);
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assert(Sequence.size() + DeadNodes - Noops == SUnits.size() &&
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"The number of nodes scheduled doesn't match the expected number!");
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}
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#endif
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/// InitDAGTopologicalSorting - create the initial topological
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/// ordering from the DAG to be scheduled.
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///
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/// The idea of the algorithm is taken from
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/// "Online algorithms for managing the topological order of
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/// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
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/// This is the MNR algorithm, which was first introduced by
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/// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
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/// "Maintaining a topological order under edge insertions".
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///
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/// Short description of the algorithm:
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///
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/// Topological ordering, ord, of a DAG maps each node to a topological
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/// index so that for all edges X->Y it is the case that ord(X) < ord(Y).
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///
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/// This means that if there is a path from the node X to the node Z,
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/// then ord(X) < ord(Z).
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///
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/// This property can be used to check for reachability of nodes:
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/// if Z is reachable from X, then an insertion of the edge Z->X would
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/// create a cycle.
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///
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/// The algorithm first computes a topological ordering for the DAG by
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/// initializing the Index2Node and Node2Index arrays and then tries to keep
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/// the ordering up-to-date after edge insertions by reordering the DAG.
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///
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/// On insertion of the edge X->Y, the algorithm first marks by calling DFS
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/// the nodes reachable from Y, and then shifts them using Shift to lie
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/// immediately after X in Index2Node.
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void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
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unsigned DAGSize = SUnits.size();
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std::vector<SUnit*> WorkList;
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WorkList.reserve(DAGSize);
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Index2Node.resize(DAGSize);
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Node2Index.resize(DAGSize);
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// Initialize the data structures.
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for (unsigned i = 0, e = DAGSize; i != e; ++i) {
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SUnit *SU = &SUnits[i];
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int NodeNum = SU->NodeNum;
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unsigned Degree = SU->Succs.size();
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// Temporarily use the Node2Index array as scratch space for degree counts.
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Node2Index[NodeNum] = Degree;
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// Is it a node without dependencies?
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if (Degree == 0) {
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assert(SU->Succs.empty() && "SUnit should have no successors");
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// Collect leaf nodes.
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WorkList.push_back(SU);
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}
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}
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int Id = DAGSize;
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while (!WorkList.empty()) {
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SUnit *SU = WorkList.back();
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WorkList.pop_back();
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Allocate(SU->NodeNum, --Id);
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for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
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I != E; ++I) {
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SUnit *SU = I->getSUnit();
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if (!--Node2Index[SU->NodeNum])
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// If all dependencies of the node are processed already,
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// then the node can be computed now.
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WorkList.push_back(SU);
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}
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}
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Visited.resize(DAGSize);
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#ifndef NDEBUG
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// Check correctness of the ordering
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for (unsigned i = 0, e = DAGSize; i != e; ++i) {
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SUnit *SU = &SUnits[i];
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for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
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I != E; ++I) {
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assert(Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] &&
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"Wrong topological sorting");
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}
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}
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#endif
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}
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/// AddPred - Updates the topological ordering to accomodate an edge
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/// to be added from SUnit X to SUnit Y.
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void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) {
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int UpperBound, LowerBound;
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LowerBound = Node2Index[Y->NodeNum];
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UpperBound = Node2Index[X->NodeNum];
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bool HasLoop = false;
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// Is Ord(X) < Ord(Y) ?
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if (LowerBound < UpperBound) {
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// Update the topological order.
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Visited.reset();
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DFS(Y, UpperBound, HasLoop);
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assert(!HasLoop && "Inserted edge creates a loop!");
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// Recompute topological indexes.
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Shift(Visited, LowerBound, UpperBound);
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}
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}
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/// RemovePred - Updates the topological ordering to accomodate an
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/// an edge to be removed from the specified node N from the predecessors
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/// of the current node M.
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void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) {
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// InitDAGTopologicalSorting();
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}
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/// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark
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/// all nodes affected by the edge insertion. These nodes will later get new
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/// topological indexes by means of the Shift method.
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void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
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bool& HasLoop) {
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std::vector<const SUnit*> WorkList;
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WorkList.reserve(SUnits.size());
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WorkList.push_back(SU);
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while (!WorkList.empty()) {
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SU = WorkList.back();
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WorkList.pop_back();
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Visited.set(SU->NodeNum);
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for (int I = SU->Succs.size()-1; I >= 0; --I) {
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int s = SU->Succs[I].getSUnit()->NodeNum;
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if (Node2Index[s] == UpperBound) {
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HasLoop = true;
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return;
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}
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// Visit successors if not already and in affected region.
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if (!Visited.test(s) && Node2Index[s] < UpperBound) {
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WorkList.push_back(SU->Succs[I].getSUnit());
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}
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}
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}
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}
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/// Shift - Renumber the nodes so that the topological ordering is
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/// preserved.
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void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound,
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int UpperBound) {
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std::vector<int> L;
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int shift = 0;
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int i;
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|
|
|
for (i = LowerBound; i <= UpperBound; ++i) {
|
|
// w is node at topological index i.
|
|
int w = Index2Node[i];
|
|
if (Visited.test(w)) {
|
|
// Unmark.
|
|
Visited.reset(w);
|
|
L.push_back(w);
|
|
shift = shift + 1;
|
|
} else {
|
|
Allocate(w, i - shift);
|
|
}
|
|
}
|
|
|
|
for (unsigned j = 0; j < L.size(); ++j) {
|
|
Allocate(L[j], i - shift);
|
|
i = i + 1;
|
|
}
|
|
}
|
|
|
|
|
|
/// WillCreateCycle - Returns true if adding an edge from SU to TargetSU will
|
|
/// create a cycle.
|
|
bool ScheduleDAGTopologicalSort::WillCreateCycle(SUnit *SU, SUnit *TargetSU) {
|
|
if (IsReachable(TargetSU, SU))
|
|
return true;
|
|
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
|
|
I != E; ++I)
|
|
if (I->isAssignedRegDep() &&
|
|
IsReachable(TargetSU, I->getSUnit()))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
/// IsReachable - Checks if SU is reachable from TargetSU.
|
|
bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU,
|
|
const SUnit *TargetSU) {
|
|
// If insertion of the edge SU->TargetSU would create a cycle
|
|
// then there is a path from TargetSU to SU.
|
|
int UpperBound, LowerBound;
|
|
LowerBound = Node2Index[TargetSU->NodeNum];
|
|
UpperBound = Node2Index[SU->NodeNum];
|
|
bool HasLoop = false;
|
|
// Is Ord(TargetSU) < Ord(SU) ?
|
|
if (LowerBound < UpperBound) {
|
|
Visited.reset();
|
|
// There may be a path from TargetSU to SU. Check for it.
|
|
DFS(TargetSU, UpperBound, HasLoop);
|
|
}
|
|
return HasLoop;
|
|
}
|
|
|
|
/// Allocate - assign the topological index to the node n.
|
|
void ScheduleDAGTopologicalSort::Allocate(int n, int index) {
|
|
Node2Index[n] = index;
|
|
Index2Node[index] = n;
|
|
}
|
|
|
|
ScheduleDAGTopologicalSort::ScheduleDAGTopologicalSort(
|
|
std::vector<SUnit> &sunits)
|
|
: SUnits(sunits) {}
|