//
// The LLVM Compiler Infrastructure
//
-// This file was developed by Evan Cheng and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "sched"
-#include "llvm/CodeGen/ScheduleDAG.h"
-#include "llvm/CodeGen/SSARegMap.h"
-#include "llvm/Target/MRegisterInfo.h"
-#include "llvm/Target/TargetMachine.h"
+#define DEBUG_TYPE "pre-RA-sched"
+#include "ScheduleDAGSDNodes.h"
+#include "llvm/CodeGen/LatencyPriorityQueue.h"
+#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
+#include "llvm/CodeGen/SchedulerRegistry.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/ADT/PriorityQueue.h"
#include "llvm/ADT/Statistic.h"
#include <climits>
-#include <iostream>
-#include <queue>
using namespace llvm;
-namespace {
- Statistic<> NumNoops ("scheduler", "Number of noops inserted");
- Statistic<> NumStalls("scheduler", "Number of pipeline stalls");
-}
+STATISTIC(NumNoops , "Number of noops inserted");
+STATISTIC(NumStalls, "Number of pipeline stalls");
+static RegisterScheduler
+ tdListDAGScheduler("list-td", "Top-down list scheduler",
+ createTDListDAGScheduler);
+
namespace {
//===----------------------------------------------------------------------===//
/// ScheduleDAGList - The actual list scheduler implementation. This supports
/// top-down scheduling.
///
-class ScheduleDAGList : public ScheduleDAG {
+class VISIBILITY_HIDDEN ScheduleDAGList : public ScheduleDAGSDNodes {
private:
/// AvailableQueue - The priority queue to use for the available SUnits.
///
/// PendingQueue - This contains all of the instructions whose operands have
/// been issued, but their results are not ready yet (due to the latency of
- /// the operation). Once the operands becomes available, the instruction is
- /// added to the AvailableQueue. This keeps track of each SUnit and the
- /// number of cycles left to execute before the operation is available.
- std::vector<std::pair<unsigned, SUnit*> > PendingQueue;
+ /// the operation). Once the operands become available, the instruction is
+ /// added to the AvailableQueue.
+ std::vector<SUnit*> PendingQueue;
/// HazardRec - The hazard recognizer to use.
- HazardRecognizer *HazardRec;
+ ScheduleHazardRecognizer *HazardRec;
public:
- ScheduleDAGList(SelectionDAG &dag, MachineBasicBlock *bb,
- const TargetMachine &tm,
+ ScheduleDAGList(MachineFunction &mf,
SchedulingPriorityQueue *availqueue,
- HazardRecognizer *HR)
- : ScheduleDAG(dag, bb, tm),
+ ScheduleHazardRecognizer *HR)
+ : ScheduleDAGSDNodes(mf),
AvailableQueue(availqueue), HazardRec(HR) {
}
void Schedule();
private:
- void ReleaseSucc(SUnit *SuccSU, bool isChain);
+ void ReleaseSucc(SUnit *SU, const SDep &D);
+ void ReleaseSuccessors(SUnit *SU);
void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
void ListScheduleTopDown();
};
} // end anonymous namespace
-HazardRecognizer::~HazardRecognizer() {}
-
-
/// Schedule - Schedule the DAG using list scheduling.
void ScheduleDAGList::Schedule() {
- DEBUG(std::cerr << "********** List Scheduling **********\n");
+ DOUT << "********** List Scheduling **********\n";
- // Build scheduling units.
- BuildSchedUnits();
+ // Build the scheduling graph.
+ BuildSchedGraph();
AvailableQueue->initNodes(SUnits);
ListScheduleTopDown();
AvailableQueue->releaseState();
-
- DEBUG(std::cerr << "*** Final schedule ***\n");
- DEBUG(dumpSchedule());
- DEBUG(std::cerr << "\n");
-
- // Emit in scheduled order
- EmitSchedule();
}
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
-/// the PendingQueue if the count reaches zero.
-void ScheduleDAGList::ReleaseSucc(SUnit *SuccSU, bool isChain) {
- if (!isChain)
- SuccSU->NumPredsLeft--;
- else
- SuccSU->NumChainPredsLeft--;
+/// the PendingQueue if the count reaches zero. Also update its cycle bound.
+void ScheduleDAGList::ReleaseSucc(SUnit *SU, const SDep &D) {
+ SUnit *SuccSU = D.getSUnit();
+ --SuccSU->NumPredsLeft;
- assert(SuccSU->NumPredsLeft >= 0 && SuccSU->NumChainPredsLeft >= 0 &&
- "List scheduling internal error");
+#ifndef NDEBUG
+ if (SuccSU->NumPredsLeft < 0) {
+ cerr << "*** Scheduling failed! ***\n";
+ SuccSU->dump(this);
+ cerr << " has been released too many times!\n";
+ llvm_unreachable();
+ }
+#endif
- if ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0) {
- // Compute how many cycles it will be before this actually becomes
- // available. This is the max of the start time of all predecessors plus
- // their latencies.
- unsigned AvailableCycle = 0;
- for (std::set<std::pair<SUnit*, bool> >::iterator I = SuccSU->Preds.begin(),
- E = SuccSU->Preds.end(); I != E; ++I) {
- // If this is a token edge, we don't need to wait for the latency of the
- // preceeding instruction (e.g. a long-latency load) unless there is also
- // some other data dependence.
- unsigned PredDoneCycle = I->first->Cycle;
- if (!I->second)
- PredDoneCycle += I->first->Latency;
- else if (I->first->Latency)
- PredDoneCycle += 1;
+ SuccSU->setDepthToAtLeast(SU->getDepth() + D.getLatency());
+
+ // If all the node's predecessors are scheduled, this node is ready
+ // to be scheduled. Ignore the special ExitSU node.
+ if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU)
+ PendingQueue.push_back(SuccSU);
+}
- AvailableCycle = std::max(AvailableCycle, PredDoneCycle);
- }
-
- PendingQueue.push_back(std::make_pair(AvailableCycle, SuccSU));
+void ScheduleDAGList::ReleaseSuccessors(SUnit *SU) {
+ // Top down: release successors.
+ for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I) {
+ assert(!I->isAssignedRegDep() &&
+ "The list-td scheduler doesn't yet support physreg dependencies!");
+
+ ReleaseSucc(SU, *I);
}
}
/// count of its successors. If a successor pending count is zero, add it to
/// the Available queue.
void ScheduleDAGList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
- DEBUG(std::cerr << "*** Scheduling [" << CurCycle << "]: ");
- DEBUG(SU->dump(&DAG));
+ DOUT << "*** Scheduling [" << CurCycle << "]: ";
+ DEBUG(SU->dump(this));
Sequence.push_back(SU);
- SU->Cycle = CurCycle;
-
- // Bottom up: release successors.
- for (std::set<std::pair<SUnit*, bool> >::iterator I = SU->Succs.begin(),
- E = SU->Succs.end(); I != E; ++I)
- ReleaseSucc(I->first, I->second);
+ assert(CurCycle >= SU->getDepth() && "Node scheduled above its depth!");
+ SU->setDepthToAtLeast(CurCycle);
+
+ ReleaseSuccessors(SU);
+ SU->isScheduled = true;
+ AvailableQueue->ScheduledNode(SU);
}
/// ListScheduleTopDown - The main loop of list scheduling for top-down
/// schedulers.
void ScheduleDAGList::ListScheduleTopDown() {
unsigned CurCycle = 0;
- SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
+
+ // Release any successors of the special Entry node.
+ ReleaseSuccessors(&EntrySU);
// All leaves to Available queue.
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
// It is available if it has no predecessors.
- if (SUnits[i].Preds.size() == 0 && &SUnits[i] != Entry) {
+ if (SUnits[i].Preds.empty()) {
AvailableQueue->push(&SUnits[i]);
- SUnits[i].isAvailable = SUnits[i].isPending = true;
+ SUnits[i].isAvailable = true;
}
}
- // Emit the entry node first.
- ScheduleNodeTopDown(Entry, CurCycle);
- HazardRec->EmitInstruction(Entry->Node);
-
// While Available queue is not empty, grab the node with the highest
// priority. If it is not ready put it back. Schedule the node.
std::vector<SUnit*> NotReady;
+ Sequence.reserve(SUnits.size());
while (!AvailableQueue->empty() || !PendingQueue.empty()) {
// Check to see if any of the pending instructions are ready to issue. If
// so, add them to the available queue.
for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
- if (PendingQueue[i].first == CurCycle) {
- AvailableQueue->push(PendingQueue[i].second);
- PendingQueue[i].second->isAvailable = true;
+ if (PendingQueue[i]->getDepth() == CurCycle) {
+ AvailableQueue->push(PendingQueue[i]);
+ PendingQueue[i]->isAvailable = true;
PendingQueue[i] = PendingQueue.back();
PendingQueue.pop_back();
--i; --e;
} else {
- assert(PendingQueue[i].first > CurCycle && "Negative latency?");
+ assert(PendingQueue[i]->getDepth() > CurCycle && "Negative latency?");
}
}
}
SUnit *FoundSUnit = 0;
- SDNode *FoundNode = 0;
bool HasNoopHazards = false;
while (!AvailableQueue->empty()) {
SUnit *CurSUnit = AvailableQueue->pop();
- // Get the node represented by this SUnit.
- FoundNode = CurSUnit->Node;
-
- // If this is a pseudo op, like copyfromreg, look to see if there is a
- // real target node flagged to it. If so, use the target node.
- for (unsigned i = 0, e = CurSUnit->FlaggedNodes.size();
- FoundNode->getOpcode() < ISD::BUILTIN_OP_END && i != e; ++i)
- FoundNode = CurSUnit->FlaggedNodes[i];
-
- HazardRecognizer::HazardType HT = HazardRec->getHazardType(FoundNode);
- if (HT == HazardRecognizer::NoHazard) {
+ ScheduleHazardRecognizer::HazardType HT =
+ HazardRec->getHazardType(CurSUnit);
+ if (HT == ScheduleHazardRecognizer::NoHazard) {
FoundSUnit = CurSUnit;
break;
}
-
+
// Remember if this is a noop hazard.
- HasNoopHazards |= HT == HazardRecognizer::NoopHazard;
+ HasNoopHazards |= HT == ScheduleHazardRecognizer::NoopHazard;
NotReady.push_back(CurSUnit);
}
// If we found a node to schedule, do it now.
if (FoundSUnit) {
ScheduleNodeTopDown(FoundSUnit, CurCycle);
- HazardRec->EmitInstruction(FoundNode);
- FoundSUnit->isScheduled = true;
- AvailableQueue->ScheduledNode(FoundSUnit);
+ HazardRec->EmitInstruction(FoundSUnit);
// If this is a pseudo-op node, we don't want to increment the current
// cycle.
} else if (!HasNoopHazards) {
// Otherwise, we have a pipeline stall, but no other problem, just advance
// the current cycle and try again.
- DEBUG(std::cerr << "*** Advancing cycle, no work to do\n");
+ DOUT << "*** Advancing cycle, no work to do\n";
HazardRec->AdvanceCycle();
++NumStalls;
++CurCycle;
// Otherwise, we have no instructions to issue and we have instructions
// that will fault if we don't do this right. This is the case for
// processors without pipeline interlocks and other cases.
- DEBUG(std::cerr << "*** Emitting noop\n");
+ DOUT << "*** Emitting noop\n";
HazardRec->EmitNoop();
- Sequence.push_back(0); // NULL SUnit* -> noop
+ Sequence.push_back(0); // NULL here means noop
++NumNoops;
++CurCycle;
}
}
#ifndef NDEBUG
- // Verify that all SUnits were scheduled.
- bool AnyNotSched = false;
- for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
- if (SUnits[i].NumPredsLeft != 0 || SUnits[i].NumChainPredsLeft != 0) {
- if (!AnyNotSched)
- std::cerr << "*** List scheduling failed! ***\n";
- SUnits[i].dump(&DAG);
- std::cerr << "has not been scheduled!\n";
- AnyNotSched = true;
- }
- }
- assert(!AnyNotSched);
+ VerifySchedule(/*isBottomUp=*/false);
#endif
}
-//===----------------------------------------------------------------------===//
-// LatencyPriorityQueue Implementation
-//===----------------------------------------------------------------------===//
-//
-// This is a SchedulingPriorityQueue that schedules using latency information to
-// reduce the length of the critical path through the basic block.
-//
-namespace {
- class LatencyPriorityQueue;
-
- /// Sorting functions for the Available queue.
- struct latency_sort : public std::binary_function<SUnit*, SUnit*, bool> {
- LatencyPriorityQueue *PQ;
- latency_sort(LatencyPriorityQueue *pq) : PQ(pq) {}
- latency_sort(const latency_sort &RHS) : PQ(RHS.PQ) {}
-
- bool operator()(const SUnit* left, const SUnit* right) const;
- };
-} // end anonymous namespace
-
-namespace {
- class LatencyPriorityQueue : public SchedulingPriorityQueue {
- // SUnits - The SUnits for the current graph.
- const std::vector<SUnit> *SUnits;
-
- // Latencies - The latency (max of latency from this node to the bb exit)
- // for each node.
- std::vector<int> Latencies;
-
- /// NumNodesSolelyBlocking - This vector contains, for every node in the
- /// Queue, the number of nodes that the node is the sole unscheduled
- /// predecessor for. This is used as a tie-breaker heuristic for better
- /// mobility.
- std::vector<unsigned> NumNodesSolelyBlocking;
-
- std::priority_queue<SUnit*, std::vector<SUnit*>, latency_sort> Queue;
-public:
- LatencyPriorityQueue() : Queue(latency_sort(this)) {
- }
-
- void initNodes(const std::vector<SUnit> &sunits) {
- SUnits = &sunits;
- // Calculate node priorities.
- CalculatePriorities();
- }
- void releaseState() {
- SUnits = 0;
- Latencies.clear();
- }
-
- unsigned getLatency(unsigned NodeNum) const {
- assert(NodeNum < Latencies.size());
- return Latencies[NodeNum];
- }
-
- unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
- assert(NodeNum < NumNodesSolelyBlocking.size());
- return NumNodesSolelyBlocking[NodeNum];
- }
-
- bool empty() const { return Queue.empty(); }
-
- virtual void push(SUnit *U) {
- push_impl(U);
- }
- void push_impl(SUnit *U);
-
- void push_all(const std::vector<SUnit *> &Nodes) {
- for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
- push_impl(Nodes[i]);
- }
-
- SUnit *pop() {
- SUnit *V = Queue.top();
- Queue.pop();
- return V;
- }
-
- // ScheduledNode - As nodes are scheduled, we look to see if there are any
- // successor nodes that have a single unscheduled predecessor. If so, that
- // single predecessor has a higher priority, since scheduling it will make
- // the node available.
- void ScheduledNode(SUnit *Node);
-
-private:
- void CalculatePriorities();
- int CalcLatency(const SUnit &SU);
- void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
-
- /// RemoveFromPriorityQueue - This is a really inefficient way to remove a
- /// node from a priority queue. We should roll our own heap to make this
- /// better or something.
- void RemoveFromPriorityQueue(SUnit *SU) {
- std::vector<SUnit*> Temp;
-
- assert(!Queue.empty() && "Not in queue!");
- while (Queue.top() != SU) {
- Temp.push_back(Queue.top());
- Queue.pop();
- assert(!Queue.empty() && "Not in queue!");
- }
-
- // Remove the node from the PQ.
- Queue.pop();
-
- // Add all the other nodes back.
- for (unsigned i = 0, e = Temp.size(); i != e; ++i)
- Queue.push(Temp[i]);
- }
- };
-}
-
-bool latency_sort::operator()(const SUnit *LHS, const SUnit *RHS) const {
- unsigned LHSNum = LHS->NodeNum;
- unsigned RHSNum = RHS->NodeNum;
-
- // The most important heuristic is scheduling the critical path.
- unsigned LHSLatency = PQ->getLatency(LHSNum);
- unsigned RHSLatency = PQ->getLatency(RHSNum);
- if (LHSLatency < RHSLatency) return true;
- if (LHSLatency > RHSLatency) return false;
-
- // After that, if two nodes have identical latencies, look to see if one will
- // unblock more other nodes than the other.
- unsigned LHSBlocked = PQ->getNumSolelyBlockNodes(LHSNum);
- unsigned RHSBlocked = PQ->getNumSolelyBlockNodes(RHSNum);
- if (LHSBlocked < RHSBlocked) return true;
- if (LHSBlocked > RHSBlocked) return false;
-
- // Finally, just to provide a stable ordering, use the node number as a
- // deciding factor.
- return LHSNum < RHSNum;
-}
-
-
-/// CalcNodePriority - Calculate the maximal path from the node to the exit.
-///
-int LatencyPriorityQueue::CalcLatency(const SUnit &SU) {
- int &Latency = Latencies[SU.NodeNum];
- if (Latency != -1)
- return Latency;
-
- int MaxSuccLatency = 0;
- for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU.Succs.begin(),
- E = SU.Succs.end(); I != E; ++I)
- MaxSuccLatency = std::max(MaxSuccLatency, CalcLatency(*I->first));
-
- return Latency = MaxSuccLatency + SU.Latency;
-}
-
-/// CalculatePriorities - Calculate priorities of all scheduling units.
-void LatencyPriorityQueue::CalculatePriorities() {
- Latencies.assign(SUnits->size(), -1);
- NumNodesSolelyBlocking.assign(SUnits->size(), 0);
-
- for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
- CalcLatency((*SUnits)[i]);
-}
-
-/// getSingleUnscheduledPred - If there is exactly one unscheduled predecessor
-/// of SU, return it, otherwise return null.
-static SUnit *getSingleUnscheduledPred(SUnit *SU) {
- SUnit *OnlyAvailablePred = 0;
- for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU->Preds.begin(),
- E = SU->Preds.end(); I != E; ++I)
- if (!I->first->isScheduled) {
- // We found an available, but not scheduled, predecessor. If it's the
- // only one we have found, keep track of it... otherwise give up.
- if (OnlyAvailablePred && OnlyAvailablePred != I->first)
- return 0;
- OnlyAvailablePred = I->first;
- }
-
- return OnlyAvailablePred;
-}
-
-void LatencyPriorityQueue::push_impl(SUnit *SU) {
- // Look at all of the successors of this node. Count the number of nodes that
- // this node is the sole unscheduled node for.
- unsigned NumNodesBlocking = 0;
- for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU->Succs.begin(),
- E = SU->Succs.end(); I != E; ++I)
- if (getSingleUnscheduledPred(I->first) == SU)
- ++NumNodesBlocking;
- NumNodesSolelyBlocking[SU->NodeNum] = NumNodesBlocking;
-
- Queue.push(SU);
-}
-
-
-// ScheduledNode - As nodes are scheduled, we look to see if there are any
-// successor nodes that have a single unscheduled predecessor. If so, that
-// single predecessor has a higher priority, since scheduling it will make
-// the node available.
-void LatencyPriorityQueue::ScheduledNode(SUnit *SU) {
- for (std::set<std::pair<SUnit*, bool> >::const_iterator I = SU->Succs.begin(),
- E = SU->Succs.end(); I != E; ++I)
- AdjustPriorityOfUnscheduledPreds(I->first);
-}
-
-/// AdjustPriorityOfUnscheduledPreds - One of the predecessors of SU was just
-/// scheduled. If SU is not itself available, then there is at least one
-/// predecessor node that has not been scheduled yet. If SU has exactly ONE
-/// unscheduled predecessor, we want to increase its priority: it getting
-/// scheduled will make this node available, so it is better than some other
-/// node of the same priority that will not make a node available.
-void LatencyPriorityQueue::AdjustPriorityOfUnscheduledPreds(SUnit *SU) {
- if (SU->isPending) return; // All preds scheduled.
-
- SUnit *OnlyAvailablePred = getSingleUnscheduledPred(SU);
- if (OnlyAvailablePred == 0 || !OnlyAvailablePred->isAvailable) return;
-
- // Okay, we found a single predecessor that is available, but not scheduled.
- // Since it is available, it must be in the priority queue. First remove it.
- RemoveFromPriorityQueue(OnlyAvailablePred);
-
- // Reinsert the node into the priority queue, which recomputes its
- // NumNodesSolelyBlocking value.
- push(OnlyAvailablePred);
-}
-
-
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
-/// createTDListDAGScheduler - This creates a top-down list scheduler with the
-/// specified hazard recognizer.
-ScheduleDAG* llvm::createTDListDAGScheduler(SelectionDAG &DAG,
- MachineBasicBlock *BB,
- HazardRecognizer *HR) {
- return new ScheduleDAGList(DAG, BB, DAG.getTarget(),
+/// createTDListDAGScheduler - This creates a top-down list scheduler with a
+/// new hazard recognizer. This scheduler takes ownership of the hazard
+/// recognizer and deletes it when done.
+ScheduleDAGSDNodes *
+llvm::createTDListDAGScheduler(SelectionDAGISel *IS, CodeGenOpt::Level) {
+ return new ScheduleDAGList(*IS->MF,
new LatencyPriorityQueue(),
- HR);
+ IS->CreateTargetHazardRecognizer());
}
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