//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "scheduler"
#include "llvm/CodeGen/LatencyPriorityQueue.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
using namespace llvm;
+#define DEBUG_TYPE "scheduler"
+
bool latency_sort::operator()(const SUnit *LHS, const SUnit *RHS) const {
+ // The isScheduleHigh flag allows nodes with wraparound dependencies that
+ // cannot easily be modeled as edges with latencies to be scheduled as
+ // soon as possible in a top-down schedule.
+ if (LHS->isScheduleHigh && !RHS->isScheduleHigh)
+ return false;
+ if (!LHS->isScheduleHigh && RHS->isScheduleHigh)
+ return true;
+
unsigned LHSNum = LHS->NodeNum;
unsigned RHSNum = RHS->NodeNum;
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;
+ return RHSNum < LHSNum;
}
-/// 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;
+ SUnit *OnlyAvailablePred = nullptr;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
- SUnit &Pred = *I->Dep;
+ SUnit &Pred = *I->getSUnit();
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;
+ return nullptr;
OnlyAvailablePred = &Pred;
}
}
-
+
return OnlyAvailablePred;
}
-void LatencyPriorityQueue::push_impl(SUnit *SU) {
+void LatencyPriorityQueue::push(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)
+ I != E; ++I) {
+ if (getSingleUnscheduledPred(I->getSUnit()) == SU)
++NumNodesBlocking;
+ }
NumNodesSolelyBlocking[SU->NodeNum] = NumNodesBlocking;
-
- Queue.push(SU);
+
+ Queue.push_back(SU);
}
-// ScheduledNode - As nodes are scheduled, we look to see if there are any
+// 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) {
+void LatencyPriorityQueue::scheduledNode(SUnit *SU) {
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
- I != E; ++I)
- AdjustPriorityOfUnscheduledPreds(I->Dep);
+ I != E; ++I) {
+ AdjustPriorityOfUnscheduledPreds(I->getSUnit());
+ }
}
/// AdjustPriorityOfUnscheduledPreds - One of the predecessors of SU was just
/// node of the same priority that will not make a node available.
void LatencyPriorityQueue::AdjustPriorityOfUnscheduledPreds(SUnit *SU) {
if (SU->isAvailable) return; // All preds scheduled.
-
+
SUnit *OnlyAvailablePred = getSingleUnscheduledPred(SU);
- if (OnlyAvailablePred == 0 || !OnlyAvailablePred->isAvailable) return;
-
+ if (!OnlyAvailablePred || !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);
// NumNodesSolelyBlocking value.
push(OnlyAvailablePred);
}
+
+SUnit *LatencyPriorityQueue::pop() {
+ if (empty()) return nullptr;
+ std::vector<SUnit *>::iterator Best = Queue.begin();
+ for (std::vector<SUnit *>::iterator I = std::next(Queue.begin()),
+ E = Queue.end(); I != E; ++I)
+ if (Picker(*Best, *I))
+ Best = I;
+ SUnit *V = *Best;
+ if (Best != std::prev(Queue.end()))
+ std::swap(*Best, Queue.back());
+ Queue.pop_back();
+ return V;
+}
+
+void LatencyPriorityQueue::remove(SUnit *SU) {
+ assert(!Queue.empty() && "Queue is empty!");
+ std::vector<SUnit *>::iterator I = std::find(Queue.begin(), Queue.end(), SU);
+ if (I != std::prev(Queue.end()))
+ std::swap(*I, Queue.back());
+ Queue.pop_back();
+}
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