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Diffstat (limited to 'release_23/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp')
| -rw-r--r-- | release_23/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp | 571 |
1 files changed, 0 insertions, 571 deletions
diff --git a/release_23/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp b/release_23/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp deleted file mode 100644 index c2fae2506794..000000000000 --- a/release_23/lib/CodeGen/SelectionDAG/ScheduleDAGList.cpp +++ /dev/null @@ -1,571 +0,0 @@ -//===---- ScheduleDAGList.cpp - Implement a list scheduler for isel DAG ---===// -// -// The LLVM Compiler Infrastructure -// -// This file is distributed under the University of Illinois Open Source -// License. See LICENSE.TXT for details. -// -//===----------------------------------------------------------------------===// -// -// 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 -// not completed execution. -// -//===----------------------------------------------------------------------===// - -#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/Statistic.h" -#include <climits> -#include <queue> -using namespace llvm; - -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 VISIBILITY_HIDDEN ScheduleDAGList : public ScheduleDAG { -private: - /// AvailableQueue - The priority queue to use for the available SUnits. - /// - SchedulingPriorityQueue *AvailableQueue; - - /// 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; - - /// HazardRec - The hazard recognizer to use. - HazardRecognizer *HazardRec; - -public: - ScheduleDAGList(SelectionDAG &dag, MachineBasicBlock *bb, - const TargetMachine &tm, - SchedulingPriorityQueue *availqueue, - HazardRecognizer *HR) - : ScheduleDAG(dag, bb, tm), - AvailableQueue(availqueue), HazardRec(HR) { - } - - ~ScheduleDAGList() { - delete HazardRec; - delete AvailableQueue; - } - - void Schedule(); - -private: - void ReleaseSucc(SUnit *SuccSU, bool isChain); - void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle); - void ListScheduleTopDown(); -}; -} // end anonymous namespace - -HazardRecognizer::~HazardRecognizer() {} - - -/// Schedule - Schedule the DAG using list scheduling. -void ScheduleDAGList::Schedule() { - DOUT << "********** List Scheduling **********\n"; - - // Build scheduling units. - BuildSchedUnits(); - - AvailableQueue->initNodes(SUnitMap, SUnits); - - ListScheduleTopDown(); - - AvailableQueue->releaseState(); - - DOUT << "*** Final schedule ***\n"; - DEBUG(dumpSchedule()); - DOUT << "\n"; - - // Emit in scheduled order - EmitSchedule(); -} - -//===----------------------------------------------------------------------===// -// Top-Down Scheduling -//===----------------------------------------------------------------------===// - -/// 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) { - SuccSU->NumPredsLeft--; - - assert(SuccSU->NumPredsLeft >= 0 && - "List scheduling internal error"); - - 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)); - } -} - -/// 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, unsigned CurCycle) { - DOUT << "*** Scheduling [" << CurCycle << "]: "; - DEBUG(SU->dump(&DAG)); - - Sequence.push_back(SU); - SU->Cycle = CurCycle; - - // Bottom up: release successors. - 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() { - 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.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 (!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; - 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) { - FoundSUnit = CurSUnit; - break; - } - - // Remember if this is a noop hazard. - HasNoopHazards |= HT == HazardRecognizer::NoopHazard; - - NotReady.push_back(CurSUnit); - } - - // Add the nodes that aren't ready back onto the available list. - if (!NotReady.empty()) { - AvailableQueue->push_all(NotReady); - NotReady.clear(); - } - - // If we found a node to schedule, do it now. - 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. - 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. - DOUT << "*** Emitting noop\n"; - HazardRec->EmitNoop(); - Sequence.push_back(0); // NULL SUnit* -> 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) { - if (!AnyNotSched) - cerr << "*** List scheduling failed! ***\n"; - SUnits[i].dump(&DAG); - cerr << "has not been scheduled!\n"; - AnyNotSched = true; - } - } - assert(!AnyNotSched); -#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. - 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(DenseMap<SDNode*, std::vector<SUnit*> > &sumap, - 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; - 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]; - } - - unsigned size() const { return Queue.size(); } - - 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() { - if (empty()) return NULL; - SUnit *V = Queue.top(); - Queue.pop(); - return V; - } - - /// remove - 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 remove(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]); - } - - // 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); - SUnit *getSingleUnscheduledPred(SUnit *SU); - }; -} - -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; - - 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(); - } - } - - 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)); - } - - 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)); - } - } -} - -/// 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; - - 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 (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; - - // 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 -//===----------------------------------------------------------------------===// - -/// 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) { - return new ScheduleDAGList(*DAG, BB, DAG->getTarget(), - new LatencyPriorityQueue(), - IS->CreateTargetHazardRecognizer()); -} |