"disable-sched-cycles", cl::Hidden, cl::init(false),
cl::desc("Disable cycle-level precision during preRA scheduling"));
+// Temporary sched=list-ilp flags until the heuristics are robust.
+// Some options are also available under sched=list-hybrid.
+static cl::opt<bool> DisableSchedRegPressure(
+ "disable-sched-reg-pressure", cl::Hidden, cl::init(false),
+ cl::desc("Disable regpressure priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedLiveUses(
+ "disable-sched-live-uses", cl::Hidden, cl::init(true),
+ cl::desc("Disable live use priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedVRegCycle(
+ "disable-sched-vrcycle", cl::Hidden, cl::init(false),
+ cl::desc("Disable virtual register cycle interference checks"));
+static cl::opt<bool> DisableSchedPhysRegJoin(
+ "disable-sched-physreg-join", cl::Hidden, cl::init(false),
+ cl::desc("Disable physreg def-use affinity"));
+static cl::opt<bool> DisableSchedStalls(
+ "disable-sched-stalls", cl::Hidden, cl::init(true),
+ cl::desc("Disable no-stall priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedCriticalPath(
+ "disable-sched-critical-path", cl::Hidden, cl::init(false),
+ cl::desc("Disable critical path priority in sched=list-ilp"));
+static cl::opt<bool> DisableSchedHeight(
+ "disable-sched-height", cl::Hidden, cl::init(false),
+ cl::desc("Disable scheduled-height priority in sched=list-ilp"));
+
+static cl::opt<int> MaxReorderWindow(
+ "max-sched-reorder", cl::Hidden, cl::init(6),
+ cl::desc("Number of instructions to allow ahead of the critical path "
+ "in sched=list-ilp"));
+
+static cl::opt<unsigned> AvgIPC(
+ "sched-avg-ipc", cl::Hidden, cl::init(1),
+ cl::desc("Average inst/cycle whan no target itinerary exists."));
+
+#ifndef NDEBUG
+namespace {
+ // For sched=list-ilp, Count the number of times each factor comes into play.
+ enum { FactPressureDiff, FactRegUses, FactStall, FactHeight, FactDepth,
+ FactStatic, FactOther, NumFactors };
+}
+static const char *FactorName[NumFactors] =
+{"PressureDiff", "RegUses", "Stall", "Height", "Depth","Static", "Other"};
+static int FactorCount[NumFactors];
+#endif //!NDEBUG
+
namespace {
//===----------------------------------------------------------------------===//
/// ScheduleDAGRRList - The actual register reduction list scheduler
/// MinAvailableCycle - Cycle of the soonest available instruction.
unsigned MinAvailableCycle;
+ /// IssueCount - Count instructions issued in this cycle
+ /// Currently valid only for bottom-up scheduling.
+ unsigned IssueCount;
+
/// LiveRegDefs - A set of physical registers and their definition
/// that are "live". These nodes must be scheduled before any other nodes that
/// modifies the registers can be scheduled.
DEBUG(dbgs()
<< "********** List Scheduling BB#" << BB->getNumber()
<< " '" << BB->getName() << "' **********\n");
+#ifndef NDEBUG
+ for (int i = 0; i < NumFactors; ++i) {
+ FactorCount[i] = 0;
+ }
+#endif //!NDEBUG
CurCycle = 0;
+ IssueCount = 0;
MinAvailableCycle = DisableSchedCycles ? 0 : UINT_MAX;
NumLiveRegs = 0;
LiveRegDefs.resize(TRI->getNumRegs(), NULL);
else
ListScheduleTopDown();
+#ifndef NDEBUG
+ for (int i = 0; i < NumFactors; ++i) {
+ DEBUG(dbgs() << FactorName[i] << "\t" << FactorCount[i] << "\n");
+ }
+#endif // !NDEBUG
AvailableQueue->releaseState();
}
if (Height < MinAvailableCycle)
MinAvailableCycle = Height;
- if (isReady(SU)) {
+ if (isReady(PredSU)) {
AvailableQueue->push(PredSU);
}
// CapturePred and others may have left the node in the pending queue, avoid
if (NextCycle <= CurCycle)
return;
+ IssueCount = 0;
AvailableQueue->setCurCycle(NextCycle);
if (!HazardRec->isEnabled()) {
// Bypass lots of virtual calls in case of long latency.
if (DisableSchedCycles)
return;
+ // FIXME: Nodes such as CopyFromReg probably should not advance the current
+ // cycle. Otherwise, we can wrongly mask real stalls. If the non-machine node
+ // has predecessors the cycle will be advanced when they are scheduled.
+ // But given the crude nature of modeling latency though such nodes, we
+ // currently need to treat these nodes like real instructions.
+ // if (!SU->getNode() || !SU->getNode()->isMachineOpcode()) return;
+
unsigned ReadyCycle = isBottomUp ? SU->getHeight() : SU->getDepth();
// Bump CurCycle to account for latency. We assume the latency of other
}
}
+static void resetVRegCycle(SUnit *SU);
+
/// 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.
#ifndef NDEBUG
if (CurCycle < SU->getHeight())
- DEBUG(dbgs() << " Height [" << SU->getHeight() << "] pipeline stall!\n");
+ DEBUG(dbgs() << " Height [" << SU->getHeight()
+ << "] pipeline stall!\n");
#endif
// FIXME: Do not modify node height. It may interfere with
// backtracking. Instead add a "ready cycle" to SUnit. Before scheduling the
- // node it's ready cycle can aid heuristics, and after scheduling it can
+ // node its ready cycle can aid heuristics, and after scheduling it can
// indicate the scheduled cycle.
SU->setHeightToAtLeast(CurCycle);
AvailableQueue->ScheduledNode(SU);
+ // If HazardRec is disabled, and each inst counts as one cycle, then
+ // advance CurCycle before ReleasePredecessors to avoid useless pushes to
+ // PendingQueue for schedulers that implement HasReadyFilter.
+ if (!HazardRec->isEnabled() && AvgIPC < 2)
+ AdvanceToCycle(CurCycle + 1);
+
// Update liveness of predecessors before successors to avoid treating a
// two-address node as a live range def.
ReleasePredecessors(SU);
}
}
+ resetVRegCycle(SU);
+
SU->isScheduled = true;
// Conditions under which the scheduler should eagerly advance the cycle:
// (1) No available instructions
// (2) All pipelines full, so available instructions must have hazards.
//
- // If HazardRec is disabled, count each inst as one cycle.
- if (!HazardRec->isEnabled() || HazardRec->atIssueLimit()
- || AvailableQueue->empty())
- AdvanceToCycle(CurCycle + 1);
+ // If HazardRec is disabled, the cycle was pre-advanced before calling
+ // ReleasePredecessors. In that case, IssueCount should remain 0.
+ //
+ // Check AvailableQueue after ReleasePredecessors in case of zero latency.
+ if (HazardRec->isEnabled() || AvgIPC > 1) {
+ if (SU->getNode() && SU->getNode()->isMachineOpcode())
+ ++IssueCount;
+ if ((HazardRec->isEnabled() && HazardRec->atIssueLimit())
+ || (!HazardRec->isEnabled() && IssueCount == AvgIPC))
+ AdvanceToCycle(CurCycle + 1);
+ }
}
/// CapturePred - This does the opposite of ReleasePred. Since SU is being
AddPred(SuccSU, D);
DelDeps.push_back(std::make_pair(SuccSU, *I));
}
+ else {
+ // Avoid scheduling the def-side copy before other successors. Otherwise
+ // we could introduce another physreg interference on the copy and
+ // continue inserting copies indefinitely.
+ SDep D(CopyFromSU, SDep::Order, /*Latency=*/0,
+ /*Reg=*/0, /*isNormalMemory=*/false,
+ /*isMustAlias=*/false, /*isArtificial=*/true);
+ AddPred(SuccSU, D);
+ }
}
for (unsigned i = 0, e = DelDeps.size(); i != e; ++i)
RemovePred(DelDeps[i].first, DelDeps[i].second);
TRI->getMinimalPhysRegClass(Reg, VT);
const TargetRegisterClass *DestRC = TRI->getCrossCopyRegClass(RC);
- // If cross copy register class is null, then it must be possible copy
- // the value directly. Do not try duplicate the def.
+ // If cross copy register class is the same as RC, then it must be possible
+ // copy the value directly. Do not try duplicate the def.
+ // If cross copy register class is not the same as RC, then it's possible to
+ // copy the value but it require cross register class copies and it is
+ // expensive.
+ // If cross copy register class is null, then it's not possible to copy
+ // the value at all.
SUnit *NewDef = 0;
- if (DestRC)
+ if (DestRC != RC) {
NewDef = CopyAndMoveSuccessors(LRDef);
- else
- DestRC = RC;
+ if (!DestRC && !NewDef)
+ report_fatal_error("Can't handle live physical register dependency!");
+ }
if (!NewDef) {
// Issue copies, these can be expensive cross register class copies.
SmallVector<SUnit*, 2> Copies;
// priority. If it is not ready put it back. Schedule the node.
Sequence.reserve(SUnits.size());
while (!AvailableQueue->empty()) {
- DEBUG(dbgs() << "\n*** Examining Available\n";
+ DEBUG(dbgs() << "\nExamining Available:\n";
AvailableQueue->dump(this));
// Pick the best node to schedule taking all constraints into
struct hybrid_ls_rr_sort : public queue_sort {
enum {
IsBottomUp = true,
- HasReadyFilter = true
+ HasReadyFilter = false
};
RegReductionPQBase *SPQ;
struct ilp_ls_rr_sort : public queue_sort {
enum {
IsBottomUp = true,
- HasReadyFilter = true
+ HasReadyFilter = false
};
RegReductionPQBase *SPQ;
std::fill(RegPressure.begin(), RegPressure.end(), 0);
for (TargetRegisterInfo::regclass_iterator I = TRI->regclass_begin(),
E = TRI->regclass_end(); I != E; ++I)
- RegLimit[(*I)->getID()] = tli->getRegPressureLimit(*I, MF);
+ RegLimit[(*I)->getID()] = tri->getRegPressureLimit(*I, MF);
}
}
unsigned getNodePriority(const SUnit *SU) const;
unsigned getNodeOrdering(const SUnit *SU) const {
+ if (!SU->getNode()) return 0;
+
return scheduleDAG->DAG->GetOrdering(SU->getNode());
}
bool HighRegPressure(const SUnit *SU) const;
- bool MayReduceRegPressure(SUnit *SU);
+ bool MayReduceRegPressure(SUnit *SU) const;
+
+ int RegPressureDiff(SUnit *SU, unsigned &LiveUses) const;
void ScheduledNode(SUnit *SU);
// Static Node Priority for Register Pressure Reduction
//===----------------------------------------------------------------------===//
+// Check for special nodes that bypass scheduling heuristics.
+// Currently this pushes TokenFactor nodes down, but may be used for other
+// pseudo-ops as well.
+//
+// Return -1 to schedule right above left, 1 for left above right.
+// Return 0 if no bias exists.
+static int checkSpecialNodes(const SUnit *left, const SUnit *right) {
+ bool LSchedLow = left->isScheduleLow;
+ bool RSchedLow = right->isScheduleLow;
+ if (LSchedLow != RSchedLow)
+ return LSchedLow < RSchedLow ? 1 : -1;
+ return 0;
+}
+
/// CalcNodeSethiUllmanNumber - Compute Sethi Ullman number.
/// Smaller number is the higher priority.
static unsigned
CalcNodeSethiUllmanNumber(&(*SUnits)[i], SethiUllmanNumbers);
}
-void RegReductionPQBase::initNodes(std::vector<SUnit> &sunits) {
- SUnits = &sunits;
- // Add pseudo dependency edges for two-address nodes.
- AddPseudoTwoAddrDeps();
- // Reroute edges to nodes with multiple uses.
- if (!TracksRegPressure)
- PrescheduleNodesWithMultipleUses();
- // Calculate node priorities.
- CalculateSethiUllmanNumbers();
-}
-
void RegReductionPQBase::addNode(const SUnit *SU) {
unsigned SUSize = SethiUllmanNumbers.size();
if (SUnits->size() > SUSize)
// If SU does not have a register def, schedule it close to its uses
// because it does not lengthen any live ranges.
return 0;
+#if 1
return SethiUllmanNumbers[SU->NodeNum];
+#else
+ unsigned Priority = SethiUllmanNumbers[SU->NodeNum];
+ if (SU->isCallOp) {
+ // FIXME: This assumes all of the defs are used as call operands.
+ int NP = (int)Priority - SU->getNode()->getNumValues();
+ return (NP > 0) ? NP : 0;
+ }
+ return Priority;
+#endif
}
//===----------------------------------------------------------------------===//
return false;
}
-bool RegReductionPQBase::MayReduceRegPressure(SUnit *SU) {
+bool RegReductionPQBase::MayReduceRegPressure(SUnit *SU) const {
const SDNode *N = SU->getNode();
if (!N->isMachineOpcode() || !SU->NumSuccs)
return false;
}
+// Compute the register pressure contribution by this instruction by count up
+// for uses that are not live and down for defs. Only count register classes
+// that are already under high pressure. As a side effect, compute the number of
+// uses of registers that are already live.
+//
+// FIXME: This encompasses the logic in HighRegPressure and MayReduceRegPressure
+// so could probably be factored.
+int RegReductionPQBase::RegPressureDiff(SUnit *SU, unsigned &LiveUses) const {
+ LiveUses = 0;
+ int PDiff = 0;
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
+ I != E; ++I) {
+ if (I->isCtrl())
+ continue;
+ SUnit *PredSU = I->getSUnit();
+ // NumRegDefsLeft is zero when enough uses of this node have been scheduled
+ // to cover the number of registers defined (they are all live).
+ if (PredSU->NumRegDefsLeft == 0) {
+ if (PredSU->getNode()->isMachineOpcode())
+ ++LiveUses;
+ continue;
+ }
+ for (ScheduleDAGSDNodes::RegDefIter RegDefPos(PredSU, scheduleDAG);
+ RegDefPos.IsValid(); RegDefPos.Advance()) {
+ EVT VT = RegDefPos.GetValue();
+ unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+ if (RegPressure[RCId] >= RegLimit[RCId])
+ ++PDiff;
+ }
+ }
+ const SDNode *N = SU->getNode();
+
+ if (!N || !N->isMachineOpcode() || !SU->NumSuccs)
+ return PDiff;
+
+ unsigned NumDefs = TII->get(N->getMachineOpcode()).getNumDefs();
+ for (unsigned i = 0; i != NumDefs; ++i) {
+ EVT VT = N->getValueType(i);
+ if (!N->hasAnyUseOfValue(i))
+ continue;
+ unsigned RCId = TLI->getRepRegClassFor(VT)->getID();
+ if (RegPressure[RCId] >= RegLimit[RCId])
+ --PDiff;
+ }
+ return PDiff;
+}
+
void RegReductionPQBase::ScheduledNode(SUnit *SU) {
if (!TracksRegPressure)
return;
+ if (!SU->getNode())
+ return;
+
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl())
return;
const SDNode *N = SU->getNode();
+ if (!N) return;
+
if (!N->isMachineOpcode()) {
if (N->getOpcode() != ISD::CopyToReg)
return;
return Scratches;
}
-/// hasOnlyLiveOutUse - Return true if SU has a single value successor that is a
+/// hasOnlyLiveInOpers - Return true if SU has only value predecessors that are
+/// CopyFromReg from a virtual register.
+static bool hasOnlyLiveInOpers(const SUnit *SU) {
+ bool RetVal = false;
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ if (I->isCtrl()) continue;
+ const SUnit *PredSU = I->getSUnit();
+ if (PredSU->getNode() &&
+ PredSU->getNode()->getOpcode() == ISD::CopyFromReg) {
+ unsigned Reg =
+ cast<RegisterSDNode>(PredSU->getNode()->getOperand(1))->getReg();
+ if (TargetRegisterInfo::isVirtualRegister(Reg)) {
+ RetVal = true;
+ continue;
+ }
+ }
+ return false;
+ }
+ return RetVal;
+}
+
+/// hasOnlyLiveOutUses - Return true if SU has only value successors that are
/// CopyToReg to a virtual register. This SU def is probably a liveout and
/// it has no other use. It should be scheduled closer to the terminator.
static bool hasOnlyLiveOutUses(const SUnit *SU) {
return RetVal;
}
-/// UnitsSharePred - Return true if the two scheduling units share a common
-/// data predecessor.
-static bool UnitsSharePred(const SUnit *left, const SUnit *right) {
- SmallSet<const SUnit*, 4> Preds;
- for (SUnit::const_pred_iterator I = left->Preds.begin(),E = left->Preds.end();
+// Set isVRegCycle for a node with only live in opers and live out uses. Also
+// set isVRegCycle for its CopyFromReg operands.
+//
+// This is only relevant for single-block loops, in which case the VRegCycle
+// node is likely an induction variable in which the operand and target virtual
+// registers should be coalesced (e.g. pre/post increment values). Setting the
+// isVRegCycle flag helps the scheduler prioritize other uses of the same
+// CopyFromReg so that this node becomes the virtual register "kill". This
+// avoids interference between the values live in and out of the block and
+// eliminates a copy inside the loop.
+static void initVRegCycle(SUnit *SU) {
+ if (DisableSchedVRegCycle)
+ return;
+
+ if (!hasOnlyLiveInOpers(SU) || !hasOnlyLiveOutUses(SU))
+ return;
+
+ DEBUG(dbgs() << "VRegCycle: SU(" << SU->NodeNum << ")\n");
+
+ SU->isVRegCycle = true;
+
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
+ I != E; ++I) {
+ if (I->isCtrl()) continue;
+ I->getSUnit()->isVRegCycle = true;
+ }
+}
+
+// After scheduling the definition of a VRegCycle, clear the isVRegCycle flag of
+// CopyFromReg operands. We should no longer penalize other uses of this VReg.
+static void resetVRegCycle(SUnit *SU) {
+ if (!SU->isVRegCycle)
+ return;
+
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl()) continue; // ignore chain preds
- Preds.insert(I->getSUnit());
+ SUnit *PredSU = I->getSUnit();
+ if (PredSU->isVRegCycle) {
+ assert(PredSU->getNode()->getOpcode() == ISD::CopyFromReg &&
+ "VRegCycle def must be CopyFromReg");
+ I->getSUnit()->isVRegCycle = 0;
+ }
}
- for (SUnit::const_pred_iterator I = right->Preds.begin(),E = right->Preds.end();
+}
+
+// Return true if this SUnit uses a CopyFromReg node marked as a VRegCycle. This
+// means a node that defines the VRegCycle has not been scheduled yet.
+static bool hasVRegCycleUse(const SUnit *SU) {
+ // If this SU also defines the VReg, don't hoist it as a "use".
+ if (SU->isVRegCycle)
+ return false;
+
+ for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl()) continue; // ignore chain preds
- if (Preds.count(I->getSUnit()))
+ if (I->getSUnit()->isVRegCycle &&
+ I->getSUnit()->getNode()->getOpcode() == ISD::CopyFromReg) {
+ DEBUG(dbgs() << " VReg cycle use: SU (" << SU->NodeNum << ")\n");
return true;
+ }
}
return false;
}
// Return 0 if latency-based priority is equivalent.
static int BUCompareLatency(SUnit *left, SUnit *right, bool checkPref,
RegReductionPQBase *SPQ) {
- // If the two nodes share an operand and one of them has a single
- // use that is a live out copy, favor the one that is live out. Otherwise
- // it will be difficult to eliminate the copy if the instruction is a
- // loop induction variable update. e.g.
- // BB:
- // sub r1, r3, #1
- // str r0, [r2, r3]
- // mov r3, r1
- // cmp
- // bne BB
- bool SharePred = UnitsSharePred(left, right);
- // FIXME: Only adjust if BB is a loop back edge.
- // FIXME: What's the cost of a copy?
- int LBonus = (SharePred && hasOnlyLiveOutUses(left)) ? 1 : 0;
- int RBonus = (SharePred && hasOnlyLiveOutUses(right)) ? 1 : 0;
- int LHeight = (int)left->getHeight() - LBonus;
- int RHeight = (int)right->getHeight() - RBonus;
+ // Scheduling an instruction that uses a VReg whose postincrement has not yet
+ // been scheduled will induce a copy. Model this as an extra cycle of latency.
+ int LPenalty = hasVRegCycleUse(left) ? 1 : 0;
+ int RPenalty = hasVRegCycleUse(right) ? 1 : 0;
+ int LHeight = (int)left->getHeight() + LPenalty;
+ int RHeight = (int)right->getHeight() + RPenalty;
bool LStall = (!checkPref || left->SchedulingPref == Sched::Latency) &&
BUHasStall(left, LHeight, SPQ);
// If scheduling either one of the node will cause a pipeline stall, sort
// them according to their height.
if (LStall) {
- if (!RStall)
+ if (!RStall) {
+ DEBUG(++FactorCount[FactStall]);
return 1;
- if (LHeight != RHeight)
+ }
+ if (LHeight != RHeight) {
+ DEBUG(++FactorCount[FactStall]);
return LHeight > RHeight ? 1 : -1;
- } else if (RStall)
+ }
+ } else if (RStall) {
+ DEBUG(++FactorCount[FactStall]);
return -1;
+ }
// If either node is scheduling for latency, sort them by height/depth
// and latency.
if (!checkPref || (left->SchedulingPref == Sched::Latency ||
right->SchedulingPref == Sched::Latency)) {
if (DisableSchedCycles) {
- if (LHeight != RHeight)
+ if (LHeight != RHeight) {
+ DEBUG(++FactorCount[FactHeight]);
return LHeight > RHeight ? 1 : -1;
+ }
}
else {
// If neither instruction stalls (!LStall && !RStall) then
- // it's height is already covered so only its depth matters. We also reach
+ // its height is already covered so only its depth matters. We also reach
// this if both stall but have the same height.
- unsigned LDepth = left->getDepth();
- unsigned RDepth = right->getDepth();
+ int LDepth = left->getDepth() - LPenalty;
+ int RDepth = right->getDepth() - RPenalty;
if (LDepth != RDepth) {
+ DEBUG(++FactorCount[FactDepth]);
DEBUG(dbgs() << " Comparing latency of SU (" << left->NodeNum
<< ") depth " << LDepth << " vs SU (" << right->NodeNum
<< ") depth " << RDepth << "\n");
return LDepth < RDepth ? 1 : -1;
}
}
- if (left->Latency != right->Latency)
+ if (left->Latency != right->Latency) {
+ DEBUG(++FactorCount[FactOther]);
return left->Latency > right->Latency ? 1 : -1;
+ }
}
return 0;
}
static bool BURRSort(SUnit *left, SUnit *right, RegReductionPQBase *SPQ) {
+ // Schedule physical register definitions close to their use. This is
+ // motivated by microarchitectures that can fuse cmp+jump macro-ops. But as
+ // long as shortening physreg live ranges is generally good, we can defer
+ // creating a subtarget hook.
+ if (!DisableSchedPhysRegJoin) {
+ bool LHasPhysReg = left->hasPhysRegDefs;
+ bool RHasPhysReg = right->hasPhysRegDefs;
+ if (LHasPhysReg != RHasPhysReg) {
+ DEBUG(++FactorCount[FactRegUses]);
+ #ifndef NDEBUG
+ const char *PhysRegMsg[] = {" has no physreg", " defines a physreg"};
+ #endif
+ DEBUG(dbgs() << " SU (" << left->NodeNum << ") "
+ << PhysRegMsg[LHasPhysReg] << " SU(" << right->NodeNum << ") "
+ << PhysRegMsg[RHasPhysReg] << "\n");
+ return LHasPhysReg < RHasPhysReg;
+ }
+ }
+
+ // Prioritize by Sethi-Ulmann number and push CopyToReg nodes down.
unsigned LPriority = SPQ->getNodePriority(left);
unsigned RPriority = SPQ->getNodePriority(right);
- if (LPriority != RPriority)
+
+ // Be really careful about hoisting call operands above previous calls.
+ // Only allows it if it would reduce register pressure.
+ if (left->isCall && right->isCallOp) {
+ unsigned RNumVals = right->getNode()->getNumValues();
+ RPriority = (RPriority > RNumVals) ? (RPriority - RNumVals) : 0;
+ }
+ if (right->isCall && left->isCallOp) {
+ unsigned LNumVals = left->getNode()->getNumValues();
+ LPriority = (LPriority > LNumVals) ? (LPriority - LNumVals) : 0;
+ }
+
+ if (LPriority != RPriority) {
+ DEBUG(++FactorCount[FactStatic]);
return LPriority > RPriority;
+ }
+
+ // One or both of the nodes are calls and their sethi-ullman numbers are the
+ // same, then keep source order.
+ if (left->isCall || right->isCall) {
+ unsigned LOrder = SPQ->getNodeOrdering(left);
+ unsigned ROrder = SPQ->getNodeOrdering(right);
+
+ // Prefer an ordering where the lower the non-zero order number, the higher
+ // the preference.
+ if ((LOrder || ROrder) && LOrder != ROrder)
+ return LOrder != 0 && (LOrder < ROrder || ROrder == 0);
+ }
// Try schedule def + use closer when Sethi-Ullman numbers are the same.
// e.g.
// This creates more short live intervals.
unsigned LDist = closestSucc(left);
unsigned RDist = closestSucc(right);
- if (LDist != RDist)
+ if (LDist != RDist) {
+ DEBUG(++FactorCount[FactOther]);
return LDist < RDist;
+ }
// How many registers becomes live when the node is scheduled.
unsigned LScratch = calcMaxScratches(left);
unsigned RScratch = calcMaxScratches(right);
- if (LScratch != RScratch)
+ if (LScratch != RScratch) {
+ DEBUG(++FactorCount[FactOther]);
return LScratch > RScratch;
+ }
+
+ // Comparing latency against a call makes little sense unless the node
+ // is register pressure-neutral.
+ if ((left->isCall && RPriority > 0) || (right->isCall && LPriority > 0))
+ return (left->NodeQueueId > right->NodeQueueId);
- if (!DisableSchedCycles) {
+ // Do not compare latencies when one or both of the nodes are calls.
+ if (!DisableSchedCycles &&
+ !(left->isCall || right->isCall)) {
int result = BUCompareLatency(left, right, false /*checkPref*/, SPQ);
if (result != 0)
return result > 0;
}
else {
- if (left->getHeight() != right->getHeight())
+ if (left->getHeight() != right->getHeight()) {
+ DEBUG(++FactorCount[FactHeight]);
return left->getHeight() > right->getHeight();
+ }
- if (left->getDepth() != right->getDepth())
+ if (left->getDepth() != right->getDepth()) {
+ DEBUG(++FactorCount[FactDepth]);
return left->getDepth() < right->getDepth();
+ }
}
assert(left->NodeQueueId && right->NodeQueueId &&
"NodeQueueId cannot be zero");
+ DEBUG(++FactorCount[FactOther]);
return (left->NodeQueueId > right->NodeQueueId);
}
// Bottom up
bool bu_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+ if (int res = checkSpecialNodes(left, right))
+ return res > 0;
+
return BURRSort(left, right, SPQ);
}
// Source order, otherwise bottom up.
bool src_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+ if (int res = checkSpecialNodes(left, right))
+ return res > 0;
+
unsigned LOrder = SPQ->getNodeOrdering(left);
unsigned ROrder = SPQ->getNodeOrdering(right);
// Return true if right should be scheduled with higher priority than left.
bool hybrid_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+ if (int res = checkSpecialNodes(left, right))
+ return res > 0;
+
if (left->isCall || right->isCall)
// No way to compute latency of calls.
return BURRSort(left, right, SPQ);
// Avoid causing spills. If register pressure is high, schedule for
// register pressure reduction.
if (LHigh && !RHigh) {
+ DEBUG(++FactorCount[FactPressureDiff]);
DEBUG(dbgs() << " pressure SU(" << left->NodeNum << ") > SU("
<< right->NodeNum << ")\n");
return true;
}
else if (!LHigh && RHigh) {
+ DEBUG(++FactorCount[FactPressureDiff]);
DEBUG(dbgs() << " pressure SU(" << right->NodeNum << ") > SU("
<< left->NodeNum << ")\n");
return false;
}
- else if (!LHigh && !RHigh) {
+ if (!LHigh && !RHigh) {
int result = BUCompareLatency(left, right, true /*checkPref*/, SPQ);
if (result != 0)
return result > 0;
!= ScheduleHazardRecognizer::NoHazard)
return false;
- return SU->getHeight() <= CurCycle;
+ return true;
}
+static bool canEnableCoalescing(SUnit *SU) {
+ unsigned Opc = SU->getNode() ? SU->getNode()->getOpcode() : 0;
+ if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
+ // CopyToReg should be close to its uses to facilitate coalescing and
+ // avoid spilling.
+ return true;
+
+ if (Opc == TargetOpcode::EXTRACT_SUBREG ||
+ Opc == TargetOpcode::SUBREG_TO_REG ||
+ Opc == TargetOpcode::INSERT_SUBREG)
+ // EXTRACT_SUBREG, INSERT_SUBREG, and SUBREG_TO_REG nodes should be
+ // close to their uses to facilitate coalescing.
+ return true;
+
+ if (SU->NumPreds == 0 && SU->NumSuccs != 0)
+ // If SU does not have a register def, schedule it close to its uses
+ // because it does not lengthen any live ranges.
+ return true;
+
+ return false;
+}
+
+// list-ilp is currently an experimental scheduler that allows various
+// heuristics to be enabled prior to the normal register reduction logic.
bool ilp_ls_rr_sort::operator()(SUnit *left, SUnit *right) const {
+ if (int res = checkSpecialNodes(left, right))
+ return res > 0;
+
if (left->isCall || right->isCall)
// No way to compute latency of calls.
return BURRSort(left, right, SPQ);
- bool LHigh = SPQ->HighRegPressure(left);
- bool RHigh = SPQ->HighRegPressure(right);
- // Avoid causing spills. If register pressure is high, schedule for
- // register pressure reduction.
- if (LHigh && !RHigh)
- return true;
- else if (!LHigh && RHigh)
- return false;
- else if (!LHigh && !RHigh) {
- // Low register pressure situation, schedule to maximize instruction level
- // parallelism.
- if (left->NumPreds > right->NumPreds)
- return false;
- else if (left->NumPreds < right->NumPreds)
- return false;
+ unsigned LLiveUses = 0, RLiveUses = 0;
+ int LPDiff = 0, RPDiff = 0;
+ if (!DisableSchedRegPressure || !DisableSchedLiveUses) {
+ LPDiff = SPQ->RegPressureDiff(left, LLiveUses);
+ RPDiff = SPQ->RegPressureDiff(right, RLiveUses);
+ }
+ if (!DisableSchedRegPressure && LPDiff != RPDiff) {
+ DEBUG(++FactorCount[FactPressureDiff]);
+ DEBUG(dbgs() << "RegPressureDiff SU(" << left->NodeNum << "): " << LPDiff
+ << " != SU(" << right->NodeNum << "): " << RPDiff << "\n");
+ return LPDiff > RPDiff;
+ }
+
+ if (!DisableSchedRegPressure && (LPDiff > 0 || RPDiff > 0)) {
+ bool LReduce = canEnableCoalescing(left);
+ bool RReduce = canEnableCoalescing(right);
+ DEBUG(if (LReduce != RReduce) ++FactorCount[FactPressureDiff]);
+ if (LReduce && !RReduce) return false;
+ if (RReduce && !LReduce) return true;
+ }
+
+ if (!DisableSchedLiveUses && (LLiveUses != RLiveUses)) {
+ DEBUG(dbgs() << "Live uses SU(" << left->NodeNum << "): " << LLiveUses
+ << " != SU(" << right->NodeNum << "): " << RLiveUses << "\n");
+ DEBUG(++FactorCount[FactRegUses]);
+ return LLiveUses < RLiveUses;
+ }
+
+ if (!DisableSchedStalls) {
+ bool LStall = BUHasStall(left, left->getHeight(), SPQ);
+ bool RStall = BUHasStall(right, right->getHeight(), SPQ);
+ if (LStall != RStall) {
+ DEBUG(++FactorCount[FactHeight]);
+ return left->getHeight() > right->getHeight();
+ }
+ }
+
+ if (!DisableSchedCriticalPath) {
+ int spread = (int)left->getDepth() - (int)right->getDepth();
+ if (std::abs(spread) > MaxReorderWindow) {
+ DEBUG(dbgs() << "Depth of SU(" << left->NodeNum << "): "
+ << left->getDepth() << " != SU(" << right->NodeNum << "): "
+ << right->getDepth() << "\n");
+ DEBUG(++FactorCount[FactDepth]);
+ return left->getDepth() < right->getDepth();
+ }
+ }
+
+ if (!DisableSchedHeight && left->getHeight() != right->getHeight()) {
+ int spread = (int)left->getHeight() - (int)right->getHeight();
+ if (std::abs(spread) > MaxReorderWindow) {
+ DEBUG(++FactorCount[FactHeight]);
+ return left->getHeight() > right->getHeight();
+ }
}
return BURRSort(left, right, SPQ);
}
+void RegReductionPQBase::initNodes(std::vector<SUnit> &sunits) {
+ SUnits = &sunits;
+ // Add pseudo dependency edges for two-address nodes.
+ AddPseudoTwoAddrDeps();
+ // Reroute edges to nodes with multiple uses.
+ if (!TracksRegPressure)
+ PrescheduleNodesWithMultipleUses();
+ // Calculate node priorities.
+ CalculateSethiUllmanNumbers();
+
+ // For single block loops, mark nodes that look like canonical IV increments.
+ if (scheduleDAG->BB->isSuccessor(scheduleDAG->BB)) {
+ for (unsigned i = 0, e = sunits.size(); i != e; ++i) {
+ initVRegCycle(&sunits[i]);
+ }
+ }
+}
+
//===----------------------------------------------------------------------===//
// Preschedule for Register Pressure
//===----------------------------------------------------------------------===//
// Top down
bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
+ if (int res = checkSpecialNodes(left, right))
+ return res < 0;
+
unsigned LPriority = SPQ->getNodePriority(left);
unsigned RPriority = SPQ->getNodePriority(right);
bool LIsTarget = left->getNode() && left->getNode()->isMachineOpcode();
projects / oota-llvm.git / blobdiff