#define DEBUG_TYPE "pre-RA-sched"
#include "llvm/CodeGen/ScheduleDAG.h"
+#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/Debug.h"
+#include <climits>
using namespace llvm;
-ScheduleDAG::ScheduleDAG(SelectionDAG *dag, MachineBasicBlock *bb,
- const TargetMachine &tm)
- : DAG(dag), BB(bb), TM(tm), MRI(BB->getParent()->getRegInfo()) {
- TII = TM.getInstrInfo();
- MF = BB->getParent();
- TRI = TM.getRegisterInfo();
- TLI = TM.getTargetLowering();
- ConstPool = MF->getConstantPool();
+ScheduleDAG::ScheduleDAG(MachineFunction &mf)
+ : TM(mf.getTarget()),
+ TII(TM.getInstrInfo()),
+ TRI(TM.getRegisterInfo()),
+ TLI(TM.getTargetLowering()),
+ MF(mf), MRI(mf.getRegInfo()),
+ ConstPool(MF.getConstantPool()),
+ EntrySU(), ExitSU() {
}
ScheduleDAG::~ScheduleDAG() {}
-/// CalculateDepths - compute depths using algorithms for the longest
-/// paths in the DAG
-void ScheduleDAG::CalculateDepths() {
- unsigned DAGSize = SUnits.size();
- std::vector<SUnit*> WorkList;
- WorkList.reserve(DAGSize);
+/// dump - dump the schedule.
+void ScheduleDAG::dumpSchedule() const {
+ for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
+ if (SUnit *SU = Sequence[i])
+ SU->dump(this);
+ else
+ cerr << "**** NOOP ****\n";
+ }
+}
- // Initialize the data structures
- for (unsigned i = 0, e = DAGSize; i != e; ++i) {
- SUnit *SU = &SUnits[i];
- unsigned Degree = SU->Preds.size();
- // Temporarily use the Depth field as scratch space for the degree count.
- SU->Depth = Degree;
- // Is it a node without dependencies?
- if (Degree == 0) {
- assert(SU->Preds.empty() && "SUnit should have no predecessors");
- // Collect leaf nodes
- WorkList.push_back(SU);
- }
- }
+/// Run - perform scheduling.
+///
+void ScheduleDAG::Run(MachineBasicBlock *bb,
+ MachineBasicBlock::iterator insertPos) {
+ BB = bb;
+ InsertPos = insertPos;
- // Process nodes in the topological order
- while (!WorkList.empty()) {
- SUnit *SU = WorkList.back();
- WorkList.pop_back();
- unsigned SUDepth = 0;
+ SUnits.clear();
+ Sequence.clear();
+ EntrySU = SUnit();
+ ExitSU = SUnit();
- // Use dynamic programming:
- // When current node is being processed, all of its dependencies
- // are already processed.
- // So, just iterate over all predecessors and take the longest path
- for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
- I != E; ++I) {
- unsigned PredDepth = I->Dep->Depth;
- if (PredDepth+1 > SUDepth) {
- SUDepth = PredDepth + 1;
- }
- }
+ Schedule();
- SU->Depth = SUDepth;
+ DOUT << "*** Final schedule ***\n";
+ DEBUG(dumpSchedule());
+ DOUT << "\n";
+}
- // Update degrees of all nodes depending on current SUnit
- for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
- I != E; ++I) {
- SUnit *SU = I->Dep;
- if (!--SU->Depth)
- // If all dependencies of the node are processed already,
- // then the longest path for the node can be computed now
- WorkList.push_back(SU);
- }
+/// addPred - This adds the specified edge as a pred of the current node if
+/// not already. It also adds the current node as a successor of the
+/// specified node.
+void SUnit::addPred(const SDep &D) {
+ // If this node already has this depenence, don't add a redundant one.
+ for (SmallVector<SDep, 4>::const_iterator I = Preds.begin(), E = Preds.end();
+ I != E; ++I)
+ if (*I == D)
+ return;
+ // Now add a corresponding succ to N.
+ SDep P = D;
+ P.setSUnit(this);
+ SUnit *N = D.getSUnit();
+ // Update the bookkeeping.
+ if (D.getKind() == SDep::Data) {
+ ++NumPreds;
+ ++N->NumSuccs;
+ }
+ if (!N->isScheduled)
+ ++NumPredsLeft;
+ if (!isScheduled)
+ ++N->NumSuccsLeft;
+ Preds.push_back(D);
+ N->Succs.push_back(P);
+ if (P.getLatency() != 0) {
+ this->setDepthDirty();
+ N->setHeightDirty();
}
}
-/// CalculateHeights - compute heights using algorithms for the longest
-/// paths in the DAG
-void ScheduleDAG::CalculateHeights() {
- unsigned DAGSize = SUnits.size();
- std::vector<SUnit*> WorkList;
- WorkList.reserve(DAGSize);
+/// removePred - This removes the specified edge as a pred of the current
+/// node if it exists. It also removes the current node as a successor of
+/// the specified node.
+void SUnit::removePred(const SDep &D) {
+ // Find the matching predecessor.
+ for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
+ I != E; ++I)
+ if (*I == D) {
+ bool FoundSucc = false;
+ // Find the corresponding successor in N.
+ SDep P = D;
+ P.setSUnit(this);
+ SUnit *N = D.getSUnit();
+ for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(),
+ EE = N->Succs.end(); II != EE; ++II)
+ if (*II == P) {
+ FoundSucc = true;
+ N->Succs.erase(II);
+ break;
+ }
+ assert(FoundSucc && "Mismatching preds / succs lists!");
+ Preds.erase(I);
+ // Update the bookkeeping.
+ if (P.getKind() == SDep::Data) {
+ --NumPreds;
+ --N->NumSuccs;
+ }
+ if (!N->isScheduled)
+ --NumPredsLeft;
+ if (!isScheduled)
+ --N->NumSuccsLeft;
+ if (P.getLatency() != 0) {
+ this->setDepthDirty();
+ N->setHeightDirty();
+ }
+ return;
+ }
+}
- // Initialize the data structures
- for (unsigned i = 0, e = DAGSize; i != e; ++i) {
- SUnit *SU = &SUnits[i];
- unsigned Degree = SU->Succs.size();
- // Temporarily use the Height field as scratch space for the degree count.
- SU->Height = Degree;
+void SUnit::setDepthDirty() {
+ if (!isDepthCurrent) return;
+ SmallVector<SUnit*, 8> WorkList;
+ WorkList.push_back(this);
+ do {
+ SUnit *SU = WorkList.pop_back_val();
+ SU->isDepthCurrent = false;
+ for (SUnit::const_succ_iterator I = SU->Succs.begin(),
+ E = SU->Succs.end(); I != E; ++I) {
+ SUnit *SuccSU = I->getSUnit();
+ if (SuccSU->isDepthCurrent)
+ WorkList.push_back(SuccSU);
+ }
+ } while (!WorkList.empty());
+}
- // Is it a node without dependencies?
- if (Degree == 0) {
- assert(SU->Succs.empty() && "Something wrong");
- assert(WorkList.empty() && "Should be empty");
- // Collect leaf nodes
- WorkList.push_back(SU);
+void SUnit::setHeightDirty() {
+ if (!isHeightCurrent) return;
+ SmallVector<SUnit*, 8> WorkList;
+ WorkList.push_back(this);
+ do {
+ SUnit *SU = WorkList.pop_back_val();
+ SU->isHeightCurrent = false;
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(),
+ E = SU->Preds.end(); I != E; ++I) {
+ SUnit *PredSU = I->getSUnit();
+ if (PredSU->isHeightCurrent)
+ WorkList.push_back(PredSU);
}
- }
+ } while (!WorkList.empty());
+}
- // Process nodes in the topological order
- while (!WorkList.empty()) {
- SUnit *SU = WorkList.back();
- WorkList.pop_back();
- unsigned SUHeight = 0;
+/// setDepthToAtLeast - Update this node's successors to reflect the
+/// fact that this node's depth just increased.
+///
+void SUnit::setDepthToAtLeast(unsigned NewDepth) {
+ if (NewDepth <= getDepth())
+ return;
+ setDepthDirty();
+ Depth = NewDepth;
+ isDepthCurrent = true;
+}
- // Use dynamic programming:
- // When current node is being processed, all of its dependencies
- // are already processed.
- // So, just iterate over all successors and take the longest path
- for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
- I != E; ++I) {
- unsigned SuccHeight = I->Dep->Height;
- if (SuccHeight+1 > SUHeight) {
- SUHeight = SuccHeight + 1;
+/// setHeightToAtLeast - Update this node's predecessors to reflect the
+/// fact that this node's height just increased.
+///
+void SUnit::setHeightToAtLeast(unsigned NewHeight) {
+ if (NewHeight <= getHeight())
+ return;
+ setHeightDirty();
+ Height = NewHeight;
+ isHeightCurrent = true;
+}
+
+/// ComputeDepth - Calculate the maximal path from the node to the exit.
+///
+void SUnit::ComputeDepth() {
+ SmallVector<SUnit*, 8> WorkList;
+ WorkList.push_back(this);
+ do {
+ SUnit *Cur = WorkList.back();
+
+ bool Done = true;
+ unsigned MaxPredDepth = 0;
+ for (SUnit::const_pred_iterator I = Cur->Preds.begin(),
+ E = Cur->Preds.end(); I != E; ++I) {
+ SUnit *PredSU = I->getSUnit();
+ if (PredSU->isDepthCurrent)
+ MaxPredDepth = std::max(MaxPredDepth,
+ PredSU->Depth + I->getLatency());
+ else {
+ Done = false;
+ WorkList.push_back(PredSU);
}
}
- SU->Height = SUHeight;
-
- // Update degrees of all nodes depending on current SUnit
- for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
- I != E; ++I) {
- SUnit *SU = I->Dep;
- if (!--SU->Height)
- // If all dependencies of the node are processed already,
- // then the longest path for the node can be computed now
- WorkList.push_back(SU);
+ if (Done) {
+ WorkList.pop_back();
+ if (MaxPredDepth != Cur->Depth) {
+ Cur->setDepthDirty();
+ Cur->Depth = MaxPredDepth;
+ }
+ Cur->isDepthCurrent = true;
}
- }
+ } while (!WorkList.empty());
}
-/// dump - dump the schedule.
-void ScheduleDAG::dumpSchedule() const {
- for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
- if (SUnit *SU = Sequence[i])
- SU->dump(this);
- else
- cerr << "**** NOOP ****\n";
- }
-}
+/// ComputeHeight - Calculate the maximal path from the node to the entry.
+///
+void SUnit::ComputeHeight() {
+ SmallVector<SUnit*, 8> WorkList;
+ WorkList.push_back(this);
+ do {
+ SUnit *Cur = WorkList.back();
+ bool Done = true;
+ unsigned MaxSuccHeight = 0;
+ for (SUnit::const_succ_iterator I = Cur->Succs.begin(),
+ E = Cur->Succs.end(); I != E; ++I) {
+ SUnit *SuccSU = I->getSUnit();
+ if (SuccSU->isHeightCurrent)
+ MaxSuccHeight = std::max(MaxSuccHeight,
+ SuccSU->Height + I->getLatency());
+ else {
+ Done = false;
+ WorkList.push_back(SuccSU);
+ }
+ }
-/// Run - perform scheduling.
-///
-void ScheduleDAG::Run() {
- Schedule();
-
- DOUT << "*** Final schedule ***\n";
- DEBUG(dumpSchedule());
- DOUT << "\n";
+ if (Done) {
+ WorkList.pop_back();
+ if (MaxSuccHeight != Cur->Height) {
+ Cur->setHeightDirty();
+ Cur->Height = MaxSuccHeight;
+ }
+ Cur->isHeightCurrent = true;
+ }
+ } while (!WorkList.empty());
}
/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
cerr << " Predecessors:\n";
for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
I != E; ++I) {
- if (I->isCtrl)
- cerr << " ch #";
- else
- cerr << " val #";
- cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
- if (I->isSpecial)
+ cerr << " ";
+ switch (I->getKind()) {
+ case SDep::Data: cerr << "val "; break;
+ case SDep::Anti: cerr << "anti"; break;
+ case SDep::Output: cerr << "out "; break;
+ case SDep::Order: cerr << "ch "; break;
+ }
+ cerr << "#";
+ cerr << I->getSUnit() << " - SU(" << I->getSUnit()->NodeNum << ")";
+ if (I->isArtificial())
cerr << " *";
cerr << "\n";
}
cerr << " Successors:\n";
for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
I != E; ++I) {
- if (I->isCtrl)
- cerr << " ch #";
- else
- cerr << " val #";
- cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
- if (I->isSpecial)
+ cerr << " ";
+ switch (I->getKind()) {
+ case SDep::Data: cerr << "val "; break;
+ case SDep::Anti: cerr << "anti"; break;
+ case SDep::Output: cerr << "out "; break;
+ case SDep::Order: cerr << "ch "; break;
+ }
+ cerr << "#";
+ cerr << I->getSUnit() << " - SU(" << I->getSUnit()->NodeNum << ")";
+ if (I->isArtificial())
cerr << " *";
cerr << "\n";
}
}
cerr << "\n";
}
+
+#ifndef NDEBUG
+/// VerifySchedule - Verify that all SUnits were scheduled and that
+/// their state is consistent.
+///
+void ScheduleDAG::VerifySchedule(bool isBottomUp) {
+ bool AnyNotSched = false;
+ unsigned DeadNodes = 0;
+ unsigned Noops = 0;
+ for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
+ if (!SUnits[i].isScheduled) {
+ if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
+ ++DeadNodes;
+ continue;
+ }
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has not been scheduled!\n";
+ AnyNotSched = true;
+ }
+ if (SUnits[i].isScheduled &&
+ (isBottomUp ? SUnits[i].getHeight() : SUnits[i].getHeight()) >
+ unsigned(INT_MAX)) {
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has an unexpected "
+ << (isBottomUp ? "Height" : "Depth") << " value!\n";
+ AnyNotSched = true;
+ }
+ if (isBottomUp) {
+ if (SUnits[i].NumSuccsLeft != 0) {
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has successors left!\n";
+ AnyNotSched = true;
+ }
+ } else {
+ if (SUnits[i].NumPredsLeft != 0) {
+ if (!AnyNotSched)
+ cerr << "*** Scheduling failed! ***\n";
+ SUnits[i].dump(this);
+ cerr << "has predecessors left!\n";
+ AnyNotSched = true;
+ }
+ }
+ }
+ for (unsigned i = 0, e = Sequence.size(); i != e; ++i)
+ if (!Sequence[i])
+ ++Noops;
+ assert(!AnyNotSched);
+ assert(Sequence.size() + DeadNodes - Noops == SUnits.size() &&
+ "The number of nodes scheduled doesn't match the expected number!");
+}
+#endif
+
+/// InitDAGTopologicalSorting - create the initial topological
+/// ordering from the DAG to be scheduled.
+///
+/// The idea of the algorithm is taken from
+/// "Online algorithms for managing the topological order of
+/// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
+/// This is the MNR algorithm, which was first introduced by
+/// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
+/// "Maintaining a topological order under edge insertions".
+///
+/// Short description of the algorithm:
+///
+/// Topological ordering, ord, of a DAG maps each node to a topological
+/// index so that for all edges X->Y it is the case that ord(X) < ord(Y).
+///
+/// This means that if there is a path from the node X to the node Z,
+/// then ord(X) < ord(Z).
+///
+/// This property can be used to check for reachability of nodes:
+/// if Z is reachable from X, then an insertion of the edge Z->X would
+/// create a cycle.
+///
+/// The algorithm first computes a topological ordering for the DAG by
+/// initializing the Index2Node and Node2Index arrays and then tries to keep
+/// the ordering up-to-date after edge insertions by reordering the DAG.
+///
+/// On insertion of the edge X->Y, the algorithm first marks by calling DFS
+/// the nodes reachable from Y, and then shifts them using Shift to lie
+/// immediately after X in Index2Node.
+void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() {
+ unsigned DAGSize = SUnits.size();
+ std::vector<SUnit*> WorkList;
+ WorkList.reserve(DAGSize);
+
+ Index2Node.resize(DAGSize);
+ Node2Index.resize(DAGSize);
+
+ // Initialize the data structures.
+ for (unsigned i = 0, e = DAGSize; i != e; ++i) {
+ SUnit *SU = &SUnits[i];
+ int NodeNum = SU->NodeNum;
+ unsigned Degree = SU->Succs.size();
+ // Temporarily use the Node2Index array as scratch space for degree counts.
+ Node2Index[NodeNum] = Degree;
+
+ // Is it a node without dependencies?
+ if (Degree == 0) {
+ assert(SU->Succs.empty() && "SUnit should have no successors");
+ // Collect leaf nodes.
+ WorkList.push_back(SU);
+ }
+ }
+
+ int Id = DAGSize;
+ while (!WorkList.empty()) {
+ SUnit *SU = WorkList.back();
+ WorkList.pop_back();
+ Allocate(SU->NodeNum, --Id);
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ SUnit *SU = I->getSUnit();
+ if (!--Node2Index[SU->NodeNum])
+ // If all dependencies of the node are processed already,
+ // then the node can be computed now.
+ WorkList.push_back(SU);
+ }
+ }
+
+ Visited.resize(DAGSize);
+
+#ifndef NDEBUG
+ // Check correctness of the ordering
+ for (unsigned i = 0, e = DAGSize; i != e; ++i) {
+ SUnit *SU = &SUnits[i];
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ assert(Node2Index[SU->NodeNum] > Node2Index[I->getSUnit()->NodeNum] &&
+ "Wrong topological sorting");
+ }
+ }
+#endif
+}
+
+/// AddPred - Updates the topological ordering to accomodate an edge
+/// to be added from SUnit X to SUnit Y.
+void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) {
+ int UpperBound, LowerBound;
+ LowerBound = Node2Index[Y->NodeNum];
+ UpperBound = Node2Index[X->NodeNum];
+ bool HasLoop = false;
+ // Is Ord(X) < Ord(Y) ?
+ if (LowerBound < UpperBound) {
+ // Update the topological order.
+ Visited.reset();
+ DFS(Y, UpperBound, HasLoop);
+ assert(!HasLoop && "Inserted edge creates a loop!");
+ // Recompute topological indexes.
+ Shift(Visited, LowerBound, UpperBound);
+ }
+}
+
+/// RemovePred - Updates the topological ordering to accomodate an
+/// an edge to be removed from the specified node N from the predecessors
+/// of the current node M.
+void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) {
+ // InitDAGTopologicalSorting();
+}
+
+/// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark
+/// all nodes affected by the edge insertion. These nodes will later get new
+/// topological indexes by means of the Shift method.
+void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound,
+ bool& HasLoop) {
+ std::vector<const SUnit*> WorkList;
+ WorkList.reserve(SUnits.size());
+
+ WorkList.push_back(SU);
+ do {
+ SU = WorkList.back();
+ WorkList.pop_back();
+ Visited.set(SU->NodeNum);
+ for (int I = SU->Succs.size()-1; I >= 0; --I) {
+ int s = SU->Succs[I].getSUnit()->NodeNum;
+ if (Node2Index[s] == UpperBound) {
+ HasLoop = true;
+ return;
+ }
+ // Visit successors if not already and in affected region.
+ if (!Visited.test(s) && Node2Index[s] < UpperBound) {
+ WorkList.push_back(SU->Succs[I].getSUnit());
+ }
+ }
+ } while (!WorkList.empty());
+}
+
+/// Shift - Renumber the nodes so that the topological ordering is
+/// preserved.
+void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound,
+ int UpperBound) {
+ std::vector<int> L;
+ int shift = 0;
+ int i;
+
+ 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) {}
+
+ScheduleHazardRecognizer::~ScheduleHazardRecognizer() {}
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