//
// 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.
//
//===----------------------------------------------------------------------===//
//
-// This implements bottom-up and top-down list schedulers, using standard
-// algorithms. The basic approach uses a priority queue of available nodes to
-// schedule. One at a time, nodes are taken from the priority queue (thus in
-// priority order), checked for legality to schedule, and emitted if legal.
+// This implements a top-down list scheduler, using standard algorithms.
+// The basic approach uses a priority queue of available nodes to schedule.
+// One at a time, nodes are taken from the priority queue (thus in priority
+// order), checked for legality to schedule, and emitted if legal.
//
// Nodes may not be legal to schedule either due to structural hazards (e.g.
// pipeline or resource constraints) or because an input to the instruction has
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "sched"
+#define DEBUG_TYPE "pre-RA-sched"
#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/CodeGen/SchedulerRegistry.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/PriorityQueue.h"
#include "llvm/ADT/Statistic.h"
#include <climits>
-#include <iostream>
-#include <queue>
-#include <set>
-#include <vector>
-#include "llvm/Support/CommandLine.h"
using namespace llvm;
-namespace {
- // FIXME: UseLatencies is temporary.
- cl::opt<bool> UseLatencies("use-sched-latencies");
- Statistic<> NumNoops ("scheduler", "Number of noops inserted");
- Statistic<> NumStalls("scheduler", "Number of pipeline stalls");
-
- /// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
- /// a group of nodes flagged together.
- struct SUnit {
- SDNode *Node; // Representative node.
- std::vector<SDNode*> FlaggedNodes; // All nodes flagged to Node.
- std::set<SUnit*> Preds; // All real predecessors.
- std::set<SUnit*> ChainPreds; // All chain predecessors.
- std::set<SUnit*> Succs; // All real successors.
- std::set<SUnit*> ChainSuccs; // All chain successors.
- short NumPredsLeft; // # of preds not scheduled.
- short NumSuccsLeft; // # of succs not scheduled.
- short NumChainPredsLeft; // # of chain preds not scheduled.
- short NumChainSuccsLeft; // # of chain succs not scheduled.
- bool isTwoAddress : 1; // Is a two-address instruction.
- bool isDefNUseOperand : 1; // Is a def&use operand.
- unsigned short Latency; // Node latency.
- unsigned CycleBound; // Upper/lower cycle to be scheduled at.
- unsigned NodeNum; // Entry # of node in the node vector.
-
- SUnit(SDNode *node, unsigned nodenum)
- : Node(node), NumPredsLeft(0), NumSuccsLeft(0),
- NumChainPredsLeft(0), NumChainSuccsLeft(0),
- isTwoAddress(false), isDefNUseOperand(false),
- Latency(0), CycleBound(0), NodeNum(nodenum) {}
-
- void dump(const SelectionDAG *G) const;
- void dumpAll(const SelectionDAG *G) const;
- };
-}
-
-void SUnit::dump(const SelectionDAG *G) const {
- std::cerr << "SU: ";
- Node->dump(G);
- std::cerr << "\n";
- if (FlaggedNodes.size() != 0) {
- for (unsigned i = 0, e = FlaggedNodes.size(); i != e; i++) {
- std::cerr << " ";
- FlaggedNodes[i]->dump(G);
- std::cerr << "\n";
- }
- }
-}
-
-void SUnit::dumpAll(const SelectionDAG *G) const {
- dump(G);
-
- std::cerr << " # preds left : " << NumPredsLeft << "\n";
- std::cerr << " # succs left : " << NumSuccsLeft << "\n";
- std::cerr << " # chain preds left : " << NumChainPredsLeft << "\n";
- std::cerr << " # chain succs left : " << NumChainSuccsLeft << "\n";
- std::cerr << " Latency : " << Latency << "\n";
-
- if (Preds.size() != 0) {
- std::cerr << " Predecessors:\n";
- for (std::set<SUnit*>::const_iterator I = Preds.begin(),
- E = Preds.end(); I != E; ++I) {
- std::cerr << " ";
- (*I)->dump(G);
- }
- }
- if (ChainPreds.size() != 0) {
- std::cerr << " Chained Preds:\n";
- for (std::set<SUnit*>::const_iterator I = ChainPreds.begin(),
- E = ChainPreds.end(); I != E; ++I) {
- std::cerr << " ";
- (*I)->dump(G);
- }
- }
- if (Succs.size() != 0) {
- std::cerr << " Successors:\n";
- for (std::set<SUnit*>::const_iterator I = Succs.begin(),
- E = Succs.end(); I != E; ++I) {
- std::cerr << " ";
- (*I)->dump(G);
- }
- }
- if (ChainSuccs.size() != 0) {
- std::cerr << " Chained succs:\n";
- for (std::set<SUnit*>::const_iterator I = ChainSuccs.begin(),
- E = ChainSuccs.end(); I != E; ++I) {
- std::cerr << " ";
- (*I)->dump(G);
- }
- }
- std::cerr << "\n";
-}
-
-//===----------------------------------------------------------------------===//
-/// SchedulingPriorityQueue - This interface is used to plug different
-/// priorities computation algorithms into the list scheduler. It implements the
-/// interface of a standard priority queue, where nodes are inserted in
-/// arbitrary order and returned in priority order. The computation of the
-/// priority and the representation of the queue are totally up to the
-/// implementation to decide.
-///
-namespace {
-class SchedulingPriorityQueue {
-public:
- virtual ~SchedulingPriorityQueue() {}
-
- virtual void initNodes(const std::vector<SUnit> &SUnits) = 0;
- virtual void releaseState() = 0;
-
- virtual bool empty() const = 0;
- virtual void push(SUnit *U) = 0;
- virtual SUnit *pop() = 0;
-};
-}
-
-
+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
-/// both top-down and bottom-up scheduling.
+/// top-down scheduling.
///
-class ScheduleDAGList : public ScheduleDAG {
+class VISIBILITY_HIDDEN ScheduleDAGList : public ScheduleDAG {
private:
- // SDNode to SUnit mapping (many to one).
- std::map<SDNode*, SUnit*> SUnitMap;
- // The schedule. Null SUnit*'s represent noop instructions.
- std::vector<SUnit*> Sequence;
- // Current scheduling cycle.
- unsigned CurrCycle;
+ /// AvailableQueue - The priority queue to use for the available SUnits.
+ ///
+ SchedulingPriorityQueue *AvailableQueue;
- // The scheduling units.
- std::vector<SUnit> 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;
- /// isBottomUp - This is true if the scheduling problem is bottom-up, false if
- /// it is top-down.
- bool isBottomUp;
-
- /// PriorityQueue - The priority queue to use.
- SchedulingPriorityQueue *PriorityQueue;
-
/// HazardRec - The hazard recognizer to use.
HazardRecognizer *HazardRec;
-
+
public:
ScheduleDAGList(SelectionDAG &dag, MachineBasicBlock *bb,
- const TargetMachine &tm, bool isbottomup,
- SchedulingPriorityQueue *priorityqueue,
+ const TargetMachine &tm,
+ SchedulingPriorityQueue *availqueue,
HazardRecognizer *HR)
- : ScheduleDAG(listSchedulingBURR, dag, bb, tm),
- CurrCycle(0), isBottomUp(isbottomup),
- PriorityQueue(priorityqueue), HazardRec(HR) {
+ : ScheduleDAG(dag, bb, tm),
+ AvailableQueue(availqueue), HazardRec(HR) {
}
~ScheduleDAGList() {
delete HazardRec;
- delete PriorityQueue;
+ delete AvailableQueue;
}
void Schedule();
- void dumpSchedule() const;
-
private:
- SUnit *NewSUnit(SDNode *N);
- void ReleasePred(SUnit *PredSU, bool isChain = false);
- void ReleaseSucc(SUnit *SuccSU, bool isChain = false);
- void ScheduleNodeBottomUp(SUnit *SU);
- void ScheduleNodeTopDown(SUnit *SU);
+ void ReleaseSucc(SUnit *SuccSU, bool isChain);
+ void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
void ListScheduleTopDown();
- void ListScheduleBottomUp();
- void BuildSchedUnits();
- void EmitSchedule();
};
} // end anonymous namespace
HazardRecognizer::~HazardRecognizer() {}
-/// NewSUnit - Creates a new SUnit and return a ptr to it.
-SUnit *ScheduleDAGList::NewSUnit(SDNode *N) {
- SUnits.push_back(SUnit(N, SUnits.size()));
- return &SUnits.back();
-}
+/// Schedule - Schedule the DAG using list scheduling.
+void ScheduleDAGList::Schedule() {
+ DOUT << "********** List Scheduling **********\n";
+
+ // Build scheduling units.
+ BuildSchedUnits();
-/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
-/// the Available queue is the count reaches zero. Also update its cycle bound.
-void ScheduleDAGList::ReleasePred(SUnit *PredSU, bool isChain) {
- // FIXME: the distance between two nodes is not always == the predecessor's
- // latency. For example, the reader can very well read the register written
- // by the predecessor later than the issue cycle. It also depends on the
- // interrupt model (drain vs. freeze).
- PredSU->CycleBound = std::max(PredSU->CycleBound,CurrCycle + PredSU->Latency);
-
- if (!isChain)
- PredSU->NumSuccsLeft--;
- else
- PredSU->NumChainSuccsLeft--;
+ AvailableQueue->initNodes(SUnits);
-#ifndef NDEBUG
- if (PredSU->NumSuccsLeft < 0 || PredSU->NumChainSuccsLeft < 0) {
- std::cerr << "*** List scheduling failed! ***\n";
- PredSU->dump(&DAG);
- std::cerr << " has been released too many times!\n";
- assert(0);
- }
-#endif
+ ListScheduleTopDown();
- if ((PredSU->NumSuccsLeft + PredSU->NumChainSuccsLeft) == 0) {
- // EntryToken has to go last! Special case it here.
- if (PredSU->Node->getOpcode() != ISD::EntryToken)
- PriorityQueue->push(PredSU);
- }
+ AvailableQueue->releaseState();
}
+//===----------------------------------------------------------------------===//
+// Top-Down Scheduling
+//===----------------------------------------------------------------------===//
+
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
-/// the Available queue is the count reaches zero. Also update its cycle bound.
+/// the PendingQueue if the count reaches zero.
void ScheduleDAGList::ReleaseSucc(SUnit *SuccSU, bool isChain) {
- // FIXME: the distance between two nodes is not always == the predecessor's
- // latency. For example, the reader can very well read the register written
- // by the predecessor later than the issue cycle. It also depends on the
- // interrupt model (drain vs. freeze).
- SuccSU->CycleBound = std::max(SuccSU->CycleBound,CurrCycle + SuccSU->Latency);
-
- if (!isChain)
- SuccSU->NumPredsLeft--;
- else
- SuccSU->NumChainPredsLeft--;
+ SuccSU->NumPredsLeft--;
-#ifndef NDEBUG
- if (SuccSU->NumPredsLeft < 0 || SuccSU->NumChainPredsLeft < 0) {
- std::cerr << "*** List scheduling failed! ***\n";
- SuccSU->dump(&DAG);
- std::cerr << " has been released too many times!\n";
- abort();
- }
-#endif
+ assert(SuccSU->NumPredsLeft >= 0 &&
+ "List scheduling internal error");
- if ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0)
- PriorityQueue->push(SuccSU);
-}
-
-/// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
-/// count of its predecessors. If a predecessor pending count is zero, add it to
-/// the Available queue.
-void ScheduleDAGList::ScheduleNodeBottomUp(SUnit *SU) {
- DEBUG(std::cerr << "*** Scheduling: ");
- DEBUG(SU->dump(&DAG));
-
- Sequence.push_back(SU);
-
- // Bottom up: release predecessors
- for (std::set<SUnit*>::iterator I1 = SU->Preds.begin(),
- E1 = SU->Preds.end(); I1 != E1; ++I1) {
- ReleasePred(*I1);
- SU->NumPredsLeft--;
+ if (SuccSU->NumPredsLeft == 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 (SUnit::pred_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.
+ SUnit &Pred = *I->Dep;
+ unsigned PredDoneCycle = Pred.Cycle;
+ if (!I->isCtrl)
+ PredDoneCycle += Pred.Latency;
+ else if (Pred.Latency)
+ PredDoneCycle += 1;
+
+ AvailableCycle = std::max(AvailableCycle, PredDoneCycle);
+ }
+
+ PendingQueue.push_back(std::make_pair(AvailableCycle, SuccSU));
}
- for (std::set<SUnit*>::iterator I2 = SU->ChainPreds.begin(),
- E2 = SU->ChainPreds.end(); I2 != E2; ++I2)
- ReleasePred(*I2, true);
-
- CurrCycle++;
}
/// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending
/// count of its successors. If a successor pending count is zero, add it to
/// the Available queue.
-void ScheduleDAGList::ScheduleNodeTopDown(SUnit *SU) {
- DEBUG(std::cerr << "*** Scheduling: ");
+void ScheduleDAGList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
+ DOUT << "*** Scheduling [" << CurCycle << "]: ";
DEBUG(SU->dump(&DAG));
Sequence.push_back(SU);
+ SU->Cycle = CurCycle;
// Bottom up: release successors.
- for (std::set<SUnit*>::iterator I1 = SU->Succs.begin(),
- E1 = SU->Succs.end(); I1 != E1; ++I1) {
- ReleaseSucc(*I1);
- SU->NumSuccsLeft--;
- }
- for (std::set<SUnit*>::iterator I2 = SU->ChainSuccs.begin(),
- E2 = SU->ChainSuccs.end(); I2 != E2; ++I2)
- ReleaseSucc(*I2, true);
-
- CurrCycle++;
-}
-
-/// isReady - True if node's lower cycle bound is less or equal to the current
-/// scheduling cycle. Always true if all nodes have uniform latency 1.
-static inline bool isReady(SUnit *SU, unsigned CurrCycle) {
- return SU->CycleBound <= CurrCycle;
-}
-
-/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
-/// schedulers.
-void ScheduleDAGList::ListScheduleBottomUp() {
- // Add root to Available queue.
- PriorityQueue->push(SUnitMap[DAG.getRoot().Val]);
-
- // 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;
- while (!PriorityQueue->empty()) {
- SUnit *CurrNode = PriorityQueue->pop();
-
- while (!isReady(CurrNode, CurrCycle)) {
- NotReady.push_back(CurrNode);
- CurrNode = PriorityQueue->pop();
- }
-
- // Add the nodes that aren't ready back onto the available list.
- while (!NotReady.empty()) {
- PriorityQueue->push(NotReady.back());
- NotReady.pop_back();
- }
-
- ScheduleNodeBottomUp(CurrNode);
- }
-
- // Add entry node last
- if (DAG.getEntryNode().Val != DAG.getRoot().Val) {
- SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
- Sequence.push_back(Entry);
- }
-
- // Reverse the order if it is bottom up.
- std::reverse(Sequence.begin(), Sequence.end());
-
-
-#ifndef NDEBUG
- // Verify that all SUnits were scheduled.
- bool AnyNotSched = false;
- for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
- if (SUnits[i].NumSuccsLeft != 0 || SUnits[i].NumChainSuccsLeft != 0) {
- if (!AnyNotSched)
- std::cerr << "*** List scheduling failed! ***\n";
- SUnits[i].dump(&DAG);
- std::cerr << "has not been scheduled!\n";
- AnyNotSched = true;
- }
- }
- assert(!AnyNotSched);
-#endif
+ for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I)
+ ReleaseSucc(I->Dep, I->isCtrl);
}
/// ListScheduleTopDown - The main loop of list scheduling for top-down
/// schedulers.
void ScheduleDAGList::ListScheduleTopDown() {
- // Emit the entry node first.
- SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
- ScheduleNodeTopDown(Entry);
- HazardRec->EmitInstruction(Entry->Node);
-
+ unsigned CurCycle = 0;
+
// 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() + SUnits[i].ChainPreds.size()) == 0 &&
- &SUnits[i] != Entry)
- PriorityQueue->push(&SUnits[i]);
+ if (SUnits[i].Preds.empty()) {
+ AvailableQueue->push(&SUnits[i]);
+ SUnits[i].isAvailable = SUnits[i].isPending = true;
+ }
}
// 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;
- while (!PriorityQueue->empty()) {
- SUnit *FoundNode = 0;
+ 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;
+ PendingQueue[i] = PendingQueue.back();
+ PendingQueue.pop_back();
+ --i; --e;
+ } else {
+ assert(PendingQueue[i].first > CurCycle && "Negative latency?");
+ }
+ }
+
+ // If there are no instructions available, don't try to issue anything, and
+ // don't advance the hazard recognizer.
+ if (AvailableQueue->empty()) {
+ ++CurCycle;
+ continue;
+ }
+ SUnit *FoundSUnit = 0;
+ SDNode *FoundNode = 0;
+
bool HasNoopHazards = false;
- do {
- SUnit *CurNode = PriorityQueue->pop();
+ while (!AvailableQueue->empty()) {
+ SUnit *CurSUnit = AvailableQueue->pop();
// Get the node represented by this SUnit.
- SDNode *N = CurNode->Node;
+ 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 = CurNode->FlaggedNodes.size();
- N->getOpcode() < ISD::BUILTIN_OP_END && i != e; ++i)
- N = CurNode->FlaggedNodes[i];
+ for (unsigned i = 0, e = CurSUnit->FlaggedNodes.size();
+ !FoundNode->isMachineOpcode() && i != e; ++i)
+ FoundNode = CurSUnit->FlaggedNodes[i];
- HazardRecognizer::HazardType HT = HazardRec->getHazardType(N);
+ HazardRecognizer::HazardType HT = HazardRec->getHazardType(FoundNode);
if (HT == HazardRecognizer::NoHazard) {
- FoundNode = CurNode;
+ FoundSUnit = CurSUnit;
break;
}
// Remember if this is a noop hazard.
HasNoopHazards |= HT == HazardRecognizer::NoopHazard;
- NotReady.push_back(CurNode);
- } while (!PriorityQueue->empty());
+ NotReady.push_back(CurSUnit);
+ }
// Add the nodes that aren't ready back onto the available list.
- while (!NotReady.empty()) {
- PriorityQueue->push(NotReady.back());
- NotReady.pop_back();
+ if (!NotReady.empty()) {
+ AvailableQueue->push_all(NotReady);
+ NotReady.clear();
}
// If we found a node to schedule, do it now.
- if (FoundNode) {
- ScheduleNodeTopDown(FoundNode);
- HazardRec->EmitInstruction(FoundNode->Node);
+ if (FoundSUnit) {
+ ScheduleNodeTopDown(FoundSUnit, CurCycle);
+ HazardRec->EmitInstruction(FoundNode);
+ FoundSUnit->isScheduled = true;
+ AvailableQueue->ScheduledNode(FoundSUnit);
+
+ // If this is a pseudo-op node, we don't want to increment the current
+ // cycle.
+ if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops!
+ ++CurCycle;
} 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;
} else {
// 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
++NumNoops;
+ ++CurCycle;
}
}
// 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 (SUnits[i].NumPredsLeft != 0) {
if (!AnyNotSched)
- std::cerr << "*** List scheduling failed! ***\n";
+ cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
- std::cerr << "has not been scheduled!\n";
+ cerr << "has not been scheduled!\n";
AnyNotSched = true;
}
}
#endif
}
-
-void ScheduleDAGList::BuildSchedUnits() {
- // Reserve entries in the vector for each of the SUnits we are creating. This
- // ensure that reallocation of the vector won't happen, so SUnit*'s won't get
- // invalidated.
- SUnits.reserve(NodeCount);
-
- const InstrItineraryData &InstrItins = TM.getInstrItineraryData();
-
- // Pass 1: create the SUnit's.
- for (unsigned i = 0, NC = NodeCount; i < NC; i++) {
- NodeInfo *NI = &Info[i];
- SDNode *N = NI->Node;
- if (isPassiveNode(N))
- continue;
-
- SUnit *SU;
- if (NI->isInGroup()) {
- if (NI != NI->Group->getBottom()) // Bottom up, so only look at bottom
- continue; // node of the NodeGroup
-
- SU = NewSUnit(N);
- // Find the flagged nodes.
- SDOperand FlagOp = N->getOperand(N->getNumOperands() - 1);
- SDNode *Flag = FlagOp.Val;
- unsigned ResNo = FlagOp.ResNo;
- while (Flag->getValueType(ResNo) == MVT::Flag) {
- NodeInfo *FNI = getNI(Flag);
- assert(FNI->Group == NI->Group);
- SU->FlaggedNodes.insert(SU->FlaggedNodes.begin(), Flag);
- SUnitMap[Flag] = SU;
-
- FlagOp = Flag->getOperand(Flag->getNumOperands() - 1);
- Flag = FlagOp.Val;
- ResNo = FlagOp.ResNo;
- }
- } else {
- SU = NewSUnit(N);
- }
- SUnitMap[N] = SU;
-
- // Compute the latency for the node. We use the sum of the latencies for
- // all nodes flagged together into this SUnit.
- if (InstrItins.isEmpty() || !UseLatencies) {
- // No latency information.
- SU->Latency = 1;
- } else {
- SU->Latency = 0;
- if (N->isTargetOpcode()) {
- unsigned SchedClass = TII->getSchedClass(N->getTargetOpcode());
- InstrStage *S = InstrItins.begin(SchedClass);
- InstrStage *E = InstrItins.end(SchedClass);
- for (; S != E; ++S)
- SU->Latency += S->Cycles;
- }
- for (unsigned i = 0, e = SU->FlaggedNodes.size(); i != e; ++i) {
- SDNode *FNode = SU->FlaggedNodes[i];
- if (FNode->isTargetOpcode()) {
- unsigned SchedClass = TII->getSchedClass(FNode->getTargetOpcode());
- InstrStage *S = InstrItins.begin(SchedClass);
- InstrStage *E = InstrItins.end(SchedClass);
- for (; S != E; ++S)
- SU->Latency += S->Cycles;
- }
- }
- }
- }
-
- // Pass 2: add the preds, succs, etc.
- for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
- SUnit *SU = &SUnits[i];
- SDNode *N = SU->Node;
- NodeInfo *NI = getNI(N);
-
- if (N->isTargetOpcode() && TII->isTwoAddrInstr(N->getTargetOpcode()))
- SU->isTwoAddress = true;
-
- if (NI->isInGroup()) {
- // Find all predecessors (of the group).
- NodeGroupOpIterator NGOI(NI);
- while (!NGOI.isEnd()) {
- SDOperand Op = NGOI.next();
- SDNode *OpN = Op.Val;
- MVT::ValueType VT = OpN->getValueType(Op.ResNo);
- NodeInfo *OpNI = getNI(OpN);
- if (OpNI->Group != NI->Group && !isPassiveNode(OpN)) {
- assert(VT != MVT::Flag);
- SUnit *OpSU = SUnitMap[OpN];
- if (VT == MVT::Other) {
- if (SU->ChainPreds.insert(OpSU).second)
- SU->NumChainPredsLeft++;
- if (OpSU->ChainSuccs.insert(SU).second)
- OpSU->NumChainSuccsLeft++;
- } else {
- if (SU->Preds.insert(OpSU).second)
- SU->NumPredsLeft++;
- if (OpSU->Succs.insert(SU).second)
- OpSU->NumSuccsLeft++;
- }
- }
- }
- } else {
- // Find node predecessors.
- for (unsigned j = 0, e = N->getNumOperands(); j != e; j++) {
- SDOperand Op = N->getOperand(j);
- SDNode *OpN = Op.Val;
- MVT::ValueType VT = OpN->getValueType(Op.ResNo);
- if (!isPassiveNode(OpN)) {
- assert(VT != MVT::Flag);
- SUnit *OpSU = SUnitMap[OpN];
- if (VT == MVT::Other) {
- if (SU->ChainPreds.insert(OpSU).second)
- SU->NumChainPredsLeft++;
- if (OpSU->ChainSuccs.insert(SU).second)
- OpSU->NumChainSuccsLeft++;
- } else {
- if (SU->Preds.insert(OpSU).second)
- SU->NumPredsLeft++;
- if (OpSU->Succs.insert(SU).second)
- OpSU->NumSuccsLeft++;
- if (j == 0 && SU->isTwoAddress)
- OpSU->isDefNUseOperand = true;
- }
- }
- }
- }
-
- DEBUG(SU->dumpAll(&DAG));
- }
-}
-
-/// EmitSchedule - Emit the machine code in scheduled order.
-void ScheduleDAGList::EmitSchedule() {
- for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
- if (SUnit *SU = Sequence[i]) {
- for (unsigned j = 0, ee = SU->FlaggedNodes.size(); j != ee; j++) {
- SDNode *N = SU->FlaggedNodes[j];
- EmitNode(getNI(N));
- }
- EmitNode(getNI(SU->Node));
- } else {
- // Null SUnit* is a noop.
- EmitNoop();
- }
- }
-}
-
-/// dump - dump the schedule.
-void ScheduleDAGList::dumpSchedule() const {
- for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
- if (SUnit *SU = Sequence[i])
- SU->dump(&DAG);
- else
- std::cerr << "**** NOOP ****\n";
- }
-}
-
-/// Schedule - Schedule the DAG using list scheduling.
-/// FIXME: Right now it only supports the burr (bottom up register reducing)
-/// heuristic.
-void ScheduleDAGList::Schedule() {
- DEBUG(std::cerr << "********** List Scheduling **********\n");
-
- // Build scheduling units.
- BuildSchedUnits();
-
- PriorityQueue->initNodes(SUnits);
-
- // Execute the actual scheduling loop Top-Down or Bottom-Up as appropriate.
- if (isBottomUp)
- ListScheduleBottomUp();
- else
- ListScheduleTopDown();
-
- PriorityQueue->releaseState();
-
- DEBUG(std::cerr << "*** Final schedule ***\n");
- DEBUG(dumpSchedule());
- DEBUG(std::cerr << "\n");
-
- // Emit in scheduled order
- EmitSchedule();
-}
-
//===----------------------------------------------------------------------===//
-// RegReductionPriorityQueue Implementation
+// LatencyPriorityQueue Implementation
//===----------------------------------------------------------------------===//
//
-// This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
-// to reduce register pressure.
+// This is a SchedulingPriorityQueue that schedules using latency information to
+// reduce the length of the critical path through the basic block.
//
namespace {
- class RegReductionPriorityQueue;
+ class LatencyPriorityQueue;
/// Sorting functions for the Available queue.
- struct ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
- RegReductionPriorityQueue *SPQ;
- ls_rr_sort(RegReductionPriorityQueue *spq) : SPQ(spq) {}
- ls_rr_sort(const ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
+ 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 RegReductionPriorityQueue : public SchedulingPriorityQueue {
+ class LatencyPriorityQueue : public SchedulingPriorityQueue {
// SUnits - The SUnits for the current graph.
- const std::vector<SUnit> *SUnits;
-
- // SethiUllmanNumbers - The SethiUllman number for each node.
- std::vector<int> SethiUllmanNumbers;
+ std::vector<SUnit> *SUnits;
- std::priority_queue<SUnit*, std::vector<SUnit*>, ls_rr_sort> Queue;
- public:
- RegReductionPriorityQueue() : Queue(ls_rr_sort(this)) {
+ // 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;
+
+ PriorityQueue<SUnit*, std::vector<SUnit*>, latency_sort> Queue;
+public:
+ LatencyPriorityQueue() : Queue(latency_sort(this)) {
}
- void initNodes(const std::vector<SUnit> &sunits) {
+ void initNodes(std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Calculate node priorities.
CalculatePriorities();
}
+
+ void addNode(const SUnit *SU) {
+ Latencies.resize(SUnits->size(), -1);
+ NumNodesSolelyBlocking.resize(SUnits->size(), 0);
+ CalcLatency(*SU);
+ }
+
+ void updateNode(const SUnit *SU) {
+ Latencies[SU->NodeNum] = -1;
+ CalcLatency(*SU);
+ }
+
void releaseState() {
SUnits = 0;
- SethiUllmanNumbers.clear();
+ Latencies.clear();
}
- unsigned getSethiUllmanNumber(unsigned NodeNum) const {
- assert(NodeNum < SethiUllmanNumbers.size());
- return SethiUllmanNumbers[NodeNum];
+ unsigned getLatency(unsigned NodeNum) const {
+ assert(NodeNum < Latencies.size());
+ return Latencies[NodeNum];
}
+ unsigned getNumSolelyBlockNodes(unsigned NodeNum) const {
+ assert(NodeNum < NumNodesSolelyBlocking.size());
+ return NumNodesSolelyBlocking[NodeNum];
+ }
+
+ unsigned size() const { return Queue.size(); }
+
bool empty() const { return Queue.empty(); }
- void push(SUnit *U) {
- Queue.push(U);
+ 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() {
+ if (empty()) return NULL;
SUnit *V = Queue.top();
Queue.pop();
return V;
}
- private:
+
+ void remove(SUnit *SU) {
+ assert(!Queue.empty() && "Not in queue!");
+ Queue.erase_one(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 ScheduledNode(SUnit *Node);
+
+private:
void CalculatePriorities();
- int CalcNodePriority(const SUnit *SU);
+ int CalcLatency(const SUnit &SU);
+ void AdjustPriorityOfUnscheduledPreds(SUnit *SU);
+ SUnit *getSingleUnscheduledPred(SUnit *SU);
};
}
-bool ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
- unsigned LeftNum = left->NodeNum;
- unsigned RightNum = right->NodeNum;
+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;
- int LBonus = (int)left ->isDefNUseOperand;
- int RBonus = (int)right->isDefNUseOperand;
+ // 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;
- // Special tie breaker: if two nodes share a operand, the one that
- // use it as a def&use operand is preferred.
- if (left->isTwoAddress && !right->isTwoAddress) {
- SDNode *DUNode = left->Node->getOperand(0).Val;
- if (DUNode->isOperand(right->Node))
- LBonus++;
- }
- if (!left->isTwoAddress && right->isTwoAddress) {
- SDNode *DUNode = right->Node->getOperand(0).Val;
- if (DUNode->isOperand(left->Node))
- RBonus++;
+ // 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;
+
+ std::vector<const SUnit*> WorkList;
+ WorkList.push_back(&SU);
+ while (!WorkList.empty()) {
+ const SUnit *Cur = WorkList.back();
+ bool AllDone = true;
+ int MaxSuccLatency = 0;
+ for (SUnit::const_succ_iterator I = Cur->Succs.begin(),E = Cur->Succs.end();
+ I != E; ++I) {
+ int SuccLatency = Latencies[I->Dep->NodeNum];
+ if (SuccLatency == -1) {
+ AllDone = false;
+ WorkList.push_back(I->Dep);
+ } else {
+ MaxSuccLatency = std::max(MaxSuccLatency, SuccLatency);
+ }
+ }
+ if (AllDone) {
+ Latencies[Cur->NodeNum] = MaxSuccLatency + Cur->Latency;
+ WorkList.pop_back();
+ }
}
-
- // Priority1 is just the number of live range genned.
- int LPriority1 = left ->NumPredsLeft - LBonus;
- int RPriority1 = right->NumPredsLeft - RBonus;
- int LPriority2 = SPQ->getSethiUllmanNumber(LeftNum) + LBonus;
- int RPriority2 = SPQ->getSethiUllmanNumber(RightNum) + RBonus;
-
- if (LPriority1 > RPriority1)
- return true;
- else if (LPriority1 == RPriority1)
- if (LPriority2 < RPriority2)
- return true;
- else if (LPriority2 == RPriority2)
- if (left->CycleBound > right->CycleBound)
- return true;
-
- return false;
+
+ return Latency;
}
+/// CalculatePriorities - Calculate priorities of all scheduling units.
+void LatencyPriorityQueue::CalculatePriorities() {
+ Latencies.assign(SUnits->size(), -1);
+ NumNodesSolelyBlocking.assign(SUnits->size(), 0);
+
+ // For each node, calculate the maximal path from the node to the exit.
+ std::vector<std::pair<const SUnit*, unsigned> > WorkList;
+ for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
+ const SUnit *SU = &(*SUnits)[i];
+ if (SU->Succs.empty())
+ WorkList.push_back(std::make_pair(SU, 0U));
+ }
-/// CalcNodePriority - Priority is the Sethi Ullman number.
-/// Smaller number is the higher priority.
-int RegReductionPriorityQueue::CalcNodePriority(const SUnit *SU) {
- int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
- if (SethiUllmanNumber != INT_MIN)
- return SethiUllmanNumber;
-
- if (SU->Preds.size() == 0) {
- SethiUllmanNumber = 1;
- } else {
- int Extra = 0;
- for (std::set<SUnit*>::iterator I = SU->Preds.begin(),
- E = SU->Preds.end(); I != E; ++I) {
- SUnit *PredSU = *I;
- int PredSethiUllman = CalcNodePriority(PredSU);
- if (PredSethiUllman > SethiUllmanNumber) {
- SethiUllmanNumber = PredSethiUllman;
- Extra = 0;
- } else if (PredSethiUllman == SethiUllmanNumber)
- Extra++;
+ while (!WorkList.empty()) {
+ const SUnit *SU = WorkList.back().first;
+ unsigned SuccLat = WorkList.back().second;
+ WorkList.pop_back();
+ int &Latency = Latencies[SU->NodeNum];
+ if (Latency == -1 || (SU->Latency + SuccLat) > (unsigned)Latency) {
+ Latency = SU->Latency + SuccLat;
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
+ I != E; ++I)
+ WorkList.push_back(std::make_pair(I->Dep, Latency));
}
-
- if (SU->Node->getOpcode() != ISD::TokenFactor)
- SethiUllmanNumber += Extra;
- else
- SethiUllmanNumber = (Extra == 1) ? 0 : Extra-1;
}
+}
+
+/// getSingleUnscheduledPred - If there is exactly one unscheduled predecessor
+/// of SU, return it, otherwise return null.
+SUnit *LatencyPriorityQueue::getSingleUnscheduledPred(SUnit *SU) {
+ SUnit *OnlyAvailablePred = 0;
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ SUnit &Pred = *I->Dep;
+ if (!Pred.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 != &Pred)
+ return 0;
+ OnlyAvailablePred = &Pred;
+ }
+ }
+
+ 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 (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I)
+ if (getSingleUnscheduledPred(I->Dep) == SU)
+ ++NumNodesBlocking;
+ NumNodesSolelyBlocking[SU->NodeNum] = NumNodesBlocking;
- return SethiUllmanNumber;
+ Queue.push(SU);
}
-/// CalculatePriorities - Calculate priorities of all scheduling units.
-void RegReductionPriorityQueue::CalculatePriorities() {
- SethiUllmanNumbers.assign(SUnits->size(), INT_MIN);
+
+// 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 (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
+ I != E; ++I)
+ AdjustPriorityOfUnscheduledPreds(I->Dep);
+}
+
+/// 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;
- for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
- CalcNodePriority(&(*SUnits)[i]);
+ // 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.
+ remove(OnlyAvailablePred);
+
+ // Reinsert the node into the priority queue, which recomputes its
+ // NumNodesSolelyBlocking value.
+ push(OnlyAvailablePred);
}
// Public Constructor Functions
//===----------------------------------------------------------------------===//
-llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAG &DAG,
- MachineBasicBlock *BB) {
- return new ScheduleDAGList(DAG, BB, DAG.getTarget(), true,
- new RegReductionPriorityQueue(),
- new HazardRecognizer());
-}
-
-/// 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(), false,
- new RegReductionPriorityQueue(),
- HR);
+/// 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.
+ScheduleDAG* llvm::createTDListDAGScheduler(SelectionDAGISel *IS,
+ SelectionDAG *DAG,
+ MachineBasicBlock *BB, bool Fast) {
+ return new ScheduleDAGList(*DAG, BB, DAG->getTarget(),
+ new LatencyPriorityQueue(),
+ IS->CreateTargetHazardRecognizer());
}
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