-//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
+//===---- ScheduleDAGInstrs.cpp - MachineInstr Rescheduling ---------------===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
//
-// This implements the ScheduleDAG class, which is a base class used by
-// scheduling implementation classes.
+// This implements the ScheduleDAGInstrs class, which implements re-scheduling
+// of MachineInstrs.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "sched-instrs"
-#include "llvm/CodeGen/ScheduleDAGInstrs.h"
+#include "ScheduleDAGInstrs.h"
+#include "llvm/Operator.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineMemOperand.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtarget.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/SmallSet.h"
using namespace llvm;
-ScheduleDAGInstrs::ScheduleDAGInstrs(MachineBasicBlock *bb,
- const TargetMachine &tm)
- : ScheduleDAG(0, bb, tm) {}
+ScheduleDAGInstrs::ScheduleDAGInstrs(MachineFunction &mf,
+ const MachineLoopInfo &mli,
+ const MachineDominatorTree &mdt)
+ : ScheduleDAG(mf), MLI(mli), MDT(mdt), Defs(TRI->getNumRegs()),
+ Uses(TRI->getNumRegs()), LoopRegs(MLI, MDT) {
+ MFI = mf.getFrameInfo();
+ DbgValueVec.clear();
+}
+
+/// Run - perform scheduling.
+///
+void ScheduleDAGInstrs::Run(MachineBasicBlock *bb,
+ MachineBasicBlock::iterator begin,
+ MachineBasicBlock::iterator end,
+ unsigned endcount) {
+ BB = bb;
+ Begin = begin;
+ InsertPosIndex = endcount;
+
+ ScheduleDAG::Run(bb, end);
+}
+
+/// getUnderlyingObjectFromInt - This is the function that does the work of
+/// looking through basic ptrtoint+arithmetic+inttoptr sequences.
+static const Value *getUnderlyingObjectFromInt(const Value *V) {
+ do {
+ if (const Operator *U = dyn_cast<Operator>(V)) {
+ // If we find a ptrtoint, we can transfer control back to the
+ // regular getUnderlyingObjectFromInt.
+ if (U->getOpcode() == Instruction::PtrToInt)
+ return U->getOperand(0);
+ // If we find an add of a constant or a multiplied value, it's
+ // likely that the other operand will lead us to the base
+ // object. We don't have to worry about the case where the
+ // object address is somehow being computed by the multiply,
+ // because our callers only care when the result is an
+ // identifibale object.
+ if (U->getOpcode() != Instruction::Add ||
+ (!isa<ConstantInt>(U->getOperand(1)) &&
+ Operator::getOpcode(U->getOperand(1)) != Instruction::Mul))
+ return V;
+ V = U->getOperand(0);
+ } else {
+ return V;
+ }
+ assert(V->getType()->isIntegerTy() && "Unexpected operand type!");
+ } while (1);
+}
+
+/// getUnderlyingObject - This is a wrapper around Value::getUnderlyingObject
+/// and adds support for basic ptrtoint+arithmetic+inttoptr sequences.
+static const Value *getUnderlyingObject(const Value *V) {
+ // First just call Value::getUnderlyingObject to let it do what it does.
+ do {
+ V = V->getUnderlyingObject();
+ // If it found an inttoptr, use special code to continue climing.
+ if (Operator::getOpcode(V) != Instruction::IntToPtr)
+ break;
+ const Value *O = getUnderlyingObjectFromInt(cast<User>(V)->getOperand(0));
+ // If that succeeded in finding a pointer, continue the search.
+ if (!O->getType()->isPointerTy())
+ break;
+ V = O;
+ } while (1);
+ return V;
+}
-void ScheduleDAGInstrs::BuildSchedUnits() {
- SUnits.clear();
+/// getUnderlyingObjectForInstr - If this machine instr has memory reference
+/// information and it can be tracked to a normal reference to a known
+/// object, return the Value for that object. Otherwise return null.
+static const Value *getUnderlyingObjectForInstr(const MachineInstr *MI,
+ const MachineFrameInfo *MFI,
+ bool &MayAlias) {
+ MayAlias = true;
+ if (!MI->hasOneMemOperand() ||
+ !(*MI->memoperands_begin())->getValue() ||
+ (*MI->memoperands_begin())->isVolatile())
+ return 0;
+
+ const Value *V = (*MI->memoperands_begin())->getValue();
+ if (!V)
+ return 0;
+
+ V = getUnderlyingObject(V);
+ if (const PseudoSourceValue *PSV = dyn_cast<PseudoSourceValue>(V)) {
+ // For now, ignore PseudoSourceValues which may alias LLVM IR values
+ // because the code that uses this function has no way to cope with
+ // such aliases.
+ if (PSV->isAliased(MFI))
+ return 0;
+
+ MayAlias = PSV->mayAlias(MFI);
+ return V;
+ }
+
+ if (isIdentifiedObject(V))
+ return V;
+
+ return 0;
+}
+
+void ScheduleDAGInstrs::StartBlock(MachineBasicBlock *BB) {
+ if (MachineLoop *ML = MLI.getLoopFor(BB))
+ if (BB == ML->getLoopLatch()) {
+ MachineBasicBlock *Header = ML->getHeader();
+ for (MachineBasicBlock::livein_iterator I = Header->livein_begin(),
+ E = Header->livein_end(); I != E; ++I)
+ LoopLiveInRegs.insert(*I);
+ LoopRegs.VisitLoop(ML);
+ }
+}
+
+void ScheduleDAGInstrs::BuildSchedGraph(AliasAnalysis *AA) {
+ // We'll be allocating one SUnit for each instruction, plus one for
+ // the region exit node.
SUnits.reserve(BB->size());
- std::vector<SUnit *> PendingLoads;
- SUnit *Terminator = 0;
- SUnit *Chain = 0;
- SUnit *Defs[TargetRegisterInfo::FirstVirtualRegister] = {};
- std::vector<SUnit *> Uses[TargetRegisterInfo::FirstVirtualRegister] = {};
- int Cost = 1; // FIXME
+ // We build scheduling units by walking a block's instruction list from bottom
+ // to top.
+
+ // Remember where a generic side-effecting instruction is as we procede.
+ SUnit *BarrierChain = 0, *AliasChain = 0;
+
+ // Memory references to specific known memory locations are tracked
+ // so that they can be given more precise dependencies. We track
+ // separately the known memory locations that may alias and those
+ // that are known not to alias
+ std::map<const Value *, SUnit *> AliasMemDefs, NonAliasMemDefs;
+ std::map<const Value *, std::vector<SUnit *> > AliasMemUses, NonAliasMemUses;
+
+ // Keep track of dangling debug references to registers.
+ std::vector<std::pair<MachineInstr*, unsigned> >
+ DanglingDebugValue(TRI->getNumRegs(),
+ std::make_pair(static_cast<MachineInstr*>(0), 0));
+
+ // Check to see if the scheduler cares about latencies.
+ bool UnitLatencies = ForceUnitLatencies();
- for (MachineBasicBlock::iterator MII = BB->end(), MIE = BB->begin();
+ // Ask the target if address-backscheduling is desirable, and if so how much.
+ const TargetSubtarget &ST = TM.getSubtarget<TargetSubtarget>();
+ unsigned SpecialAddressLatency = ST.getSpecialAddressLatency();
+
+ // Remove any stale debug info; sometimes BuildSchedGraph is called again
+ // without emitting the info from the previous call.
+ DbgValueVec.clear();
+
+ // Walk the list of instructions, from bottom moving up.
+ for (MachineBasicBlock::iterator MII = InsertPos, MIE = Begin;
MII != MIE; --MII) {
MachineInstr *MI = prior(MII);
+ // DBG_VALUE does not have SUnit's built, so just remember these for later
+ // reinsertion.
+ if (MI->isDebugValue()) {
+ if (MI->getNumOperands()==3 && MI->getOperand(0).isReg() &&
+ MI->getOperand(0).getReg())
+ DanglingDebugValue[MI->getOperand(0).getReg()] =
+ std::make_pair(MI, DbgValueVec.size());
+ DbgValueVec.push_back(MI);
+ continue;
+ }
+ const TargetInstrDesc &TID = MI->getDesc();
+ assert(!TID.isTerminator() && !MI->isLabel() &&
+ "Cannot schedule terminators or labels!");
+ // Create the SUnit for this MI.
SUnit *SU = NewSUnit(MI);
+ // Assign the Latency field of SU using target-provided information.
+ if (UnitLatencies)
+ SU->Latency = 1;
+ else
+ ComputeLatency(SU);
+
+ // Add register-based dependencies (data, anti, and output).
for (unsigned j = 0, n = MI->getNumOperands(); j != n; ++j) {
const MachineOperand &MO = MI->getOperand(j);
if (!MO.isReg()) continue;
if (Reg == 0) continue;
assert(TRI->isPhysicalRegister(Reg) && "Virtual register encountered!");
+
+ if (MO.isDef() && DanglingDebugValue[Reg].first!=0) {
+ SU->DbgInstrList.push_back(DanglingDebugValue[Reg].first);
+ DbgValueVec[DanglingDebugValue[Reg].second] = 0;
+ DanglingDebugValue[Reg] = std::make_pair((MachineInstr*)0, 0);
+ }
+
std::vector<SUnit *> &UseList = Uses[Reg];
- SUnit *&Def = Defs[Reg];
- // Optionally add output and anti dependences.
- if (Def && Def != SU)
- Def->addPred(SU, /*isCtrl=*/true, /*isSpecial=*/false,
- /*PhyReg=*/Reg, Cost);
+ std::vector<SUnit *> &DefList = Defs[Reg];
+ // Optionally add output and anti dependencies. For anti
+ // dependencies we use a latency of 0 because for a multi-issue
+ // target we want to allow the defining instruction to issue
+ // in the same cycle as the using instruction.
+ // TODO: Using a latency of 1 here for output dependencies assumes
+ // there's no cost for reusing registers.
+ SDep::Kind Kind = MO.isUse() ? SDep::Anti : SDep::Output;
+ unsigned AOLatency = (Kind == SDep::Anti) ? 0 : 1;
+ for (unsigned i = 0, e = DefList.size(); i != e; ++i) {
+ SUnit *DefSU = DefList[i];
+ if (DefSU != SU &&
+ (Kind != SDep::Output || !MO.isDead() ||
+ !DefSU->getInstr()->registerDefIsDead(Reg)))
+ DefSU->addPred(SDep(SU, Kind, AOLatency, /*Reg=*/Reg));
+ }
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- SUnit *&Def = Defs[*Alias];
- if (Def && Def != SU)
- Def->addPred(SU, /*isCtrl=*/true, /*isSpecial=*/false,
- /*PhyReg=*/*Alias, Cost);
+ std::vector<SUnit *> &DefList = Defs[*Alias];
+ for (unsigned i = 0, e = DefList.size(); i != e; ++i) {
+ SUnit *DefSU = DefList[i];
+ if (DefSU != SU &&
+ (Kind != SDep::Output || !MO.isDead() ||
+ !DefSU->getInstr()->registerDefIsDead(*Alias)))
+ DefSU->addPred(SDep(SU, Kind, AOLatency, /*Reg=*/ *Alias));
+ }
}
if (MO.isDef()) {
// Add any data dependencies.
- for (unsigned i = 0, e = UseList.size(); i != e; ++i)
- if (UseList[i] != SU)
- UseList[i]->addPred(SU, /*isCtrl=*/false, /*isSpecial=*/false,
- /*PhysReg=*/Reg, Cost);
+ unsigned DataLatency = SU->Latency;
+ for (unsigned i = 0, e = UseList.size(); i != e; ++i) {
+ SUnit *UseSU = UseList[i];
+ if (UseSU == SU)
+ continue;
+ unsigned LDataLatency = DataLatency;
+ // Optionally add in a special extra latency for nodes that
+ // feed addresses.
+ // TODO: Do this for register aliases too.
+ // TODO: Perhaps we should get rid of
+ // SpecialAddressLatency and just move this into
+ // adjustSchedDependency for the targets that care about it.
+ if (SpecialAddressLatency != 0 && !UnitLatencies) {
+ MachineInstr *UseMI = UseSU->getInstr();
+ const TargetInstrDesc &UseTID = UseMI->getDesc();
+ int RegUseIndex = UseMI->findRegisterUseOperandIdx(Reg);
+ assert(RegUseIndex >= 0 && "UseMI doesn's use register!");
+ if ((UseTID.mayLoad() || UseTID.mayStore()) &&
+ (unsigned)RegUseIndex < UseTID.getNumOperands() &&
+ UseTID.OpInfo[RegUseIndex].isLookupPtrRegClass())
+ LDataLatency += SpecialAddressLatency;
+ }
+ // Adjust the dependence latency using operand def/use
+ // information (if any), and then allow the target to
+ // perform its own adjustments.
+ const SDep& dep = SDep(SU, SDep::Data, LDataLatency, Reg);
+ if (!UnitLatencies) {
+ ComputeOperandLatency(SU, UseSU, const_cast<SDep &>(dep));
+ ST.adjustSchedDependency(SU, UseSU, const_cast<SDep &>(dep));
+ }
+ UseSU->addPred(dep);
+ }
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
std::vector<SUnit *> &UseList = Uses[*Alias];
- for (unsigned i = 0, e = UseList.size(); i != e; ++i)
- if (UseList[i] != SU)
- UseList[i]->addPred(SU, /*isCtrl=*/false, /*isSpecial=*/false,
- /*PhysReg=*/*Alias, Cost);
+ for (unsigned i = 0, e = UseList.size(); i != e; ++i) {
+ SUnit *UseSU = UseList[i];
+ if (UseSU == SU)
+ continue;
+ const SDep& dep = SDep(SU, SDep::Data, DataLatency, *Alias);
+ if (!UnitLatencies) {
+ ComputeOperandLatency(SU, UseSU, const_cast<SDep &>(dep));
+ ST.adjustSchedDependency(SU, UseSU, const_cast<SDep &>(dep));
+ }
+ UseSU->addPred(dep);
+ }
+ }
+
+ // If a def is going to wrap back around to the top of the loop,
+ // backschedule it.
+ if (!UnitLatencies && DefList.empty()) {
+ LoopDependencies::LoopDeps::iterator I = LoopRegs.Deps.find(Reg);
+ if (I != LoopRegs.Deps.end()) {
+ const MachineOperand *UseMO = I->second.first;
+ unsigned Count = I->second.second;
+ const MachineInstr *UseMI = UseMO->getParent();
+ unsigned UseMOIdx = UseMO - &UseMI->getOperand(0);
+ const TargetInstrDesc &UseTID = UseMI->getDesc();
+ // TODO: If we knew the total depth of the region here, we could
+ // handle the case where the whole loop is inside the region but
+ // is large enough that the isScheduleHigh trick isn't needed.
+ if (UseMOIdx < UseTID.getNumOperands()) {
+ // Currently, we only support scheduling regions consisting of
+ // single basic blocks. Check to see if the instruction is in
+ // the same region by checking to see if it has the same parent.
+ if (UseMI->getParent() != MI->getParent()) {
+ unsigned Latency = SU->Latency;
+ if (UseTID.OpInfo[UseMOIdx].isLookupPtrRegClass())
+ Latency += SpecialAddressLatency;
+ // This is a wild guess as to the portion of the latency which
+ // will be overlapped by work done outside the current
+ // scheduling region.
+ Latency -= std::min(Latency, Count);
+ // Add the artifical edge.
+ ExitSU.addPred(SDep(SU, SDep::Order, Latency,
+ /*Reg=*/0, /*isNormalMemory=*/false,
+ /*isMustAlias=*/false,
+ /*isArtificial=*/true));
+ } else if (SpecialAddressLatency > 0 &&
+ UseTID.OpInfo[UseMOIdx].isLookupPtrRegClass()) {
+ // The entire loop body is within the current scheduling region
+ // and the latency of this operation is assumed to be greater
+ // than the latency of the loop.
+ // TODO: Recursively mark data-edge predecessors as
+ // isScheduleHigh too.
+ SU->isScheduleHigh = true;
+ }
+ }
+ LoopRegs.Deps.erase(I);
+ }
}
UseList.clear();
- Def = SU;
+ if (!MO.isDead())
+ DefList.clear();
+ DefList.push_back(SU);
} else {
UseList.push_back(SU);
}
}
- bool False = false;
- bool True = true;
- if (!MI->isSafeToMove(TII, False)) {
- if (Chain)
- Chain->addPred(SU, /*isCtrl=*/false, /*isSpecial=*/false);
+
+ // Add chain dependencies.
+ // Chain dependencies used to enforce memory order should have
+ // latency of 0 (except for true dependency of Store followed by
+ // aliased Load... we estimate that with a single cycle of latency
+ // assuming the hardware will bypass)
+ // Note that isStoreToStackSlot and isLoadFromStackSLot are not usable
+ // after stack slots are lowered to actual addresses.
+ // TODO: Use an AliasAnalysis and do real alias-analysis queries, and
+ // produce more precise dependence information.
+#define STORE_LOAD_LATENCY 1
+ unsigned TrueMemOrderLatency = 0;
+ if (TID.isCall() || TID.hasUnmodeledSideEffects() ||
+ (MI->hasVolatileMemoryRef() &&
+ (!TID.mayLoad() || !MI->isInvariantLoad(AA)))) {
+ // Be conservative with these and add dependencies on all memory
+ // references, even those that are known to not alias.
+ for (std::map<const Value *, SUnit *>::iterator I =
+ NonAliasMemDefs.begin(), E = NonAliasMemDefs.end(); I != E; ++I) {
+ I->second->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ }
+ for (std::map<const Value *, std::vector<SUnit *> >::iterator I =
+ NonAliasMemUses.begin(), E = NonAliasMemUses.end(); I != E; ++I) {
+ for (unsigned i = 0, e = I->second.size(); i != e; ++i)
+ I->second[i]->addPred(SDep(SU, SDep::Order, TrueMemOrderLatency));
+ }
+ NonAliasMemDefs.clear();
+ NonAliasMemUses.clear();
+ // Add SU to the barrier chain.
+ if (BarrierChain)
+ BarrierChain->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ BarrierChain = SU;
+
+ // fall-through
+ new_alias_chain:
+ // Chain all possibly aliasing memory references though SU.
+ if (AliasChain)
+ AliasChain->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ AliasChain = SU;
for (unsigned k = 0, m = PendingLoads.size(); k != m; ++k)
- PendingLoads[k]->addPred(SU, /*isCtrl=*/false, /*isSpecial=*/false);
+ PendingLoads[k]->addPred(SDep(SU, SDep::Order, TrueMemOrderLatency));
+ for (std::map<const Value *, SUnit *>::iterator I = AliasMemDefs.begin(),
+ E = AliasMemDefs.end(); I != E; ++I) {
+ I->second->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ }
+ for (std::map<const Value *, std::vector<SUnit *> >::iterator I =
+ AliasMemUses.begin(), E = AliasMemUses.end(); I != E; ++I) {
+ for (unsigned i = 0, e = I->second.size(); i != e; ++i)
+ I->second[i]->addPred(SDep(SU, SDep::Order, TrueMemOrderLatency));
+ }
PendingLoads.clear();
- Chain = SU;
- } else if (!MI->isSafeToMove(TII, True)) {
- if (Chain)
- Chain->addPred(SU, /*isCtrl=*/false, /*isSpecial=*/false);
- PendingLoads.push_back(SU);
+ AliasMemDefs.clear();
+ AliasMemUses.clear();
+ } else if (TID.mayStore()) {
+ bool MayAlias = true;
+ TrueMemOrderLatency = STORE_LOAD_LATENCY;
+ if (const Value *V = getUnderlyingObjectForInstr(MI, MFI, MayAlias)) {
+ // A store to a specific PseudoSourceValue. Add precise dependencies.
+ // Record the def in MemDefs, first adding a dep if there is
+ // an existing def.
+ std::map<const Value *, SUnit *>::iterator I =
+ ((MayAlias) ? AliasMemDefs.find(V) : NonAliasMemDefs.find(V));
+ std::map<const Value *, SUnit *>::iterator IE =
+ ((MayAlias) ? AliasMemDefs.end() : NonAliasMemDefs.end());
+ if (I != IE) {
+ I->second->addPred(SDep(SU, SDep::Order, /*Latency=*/0, /*Reg=*/0,
+ /*isNormalMemory=*/true));
+ I->second = SU;
+ } else {
+ if (MayAlias)
+ AliasMemDefs[V] = SU;
+ else
+ NonAliasMemDefs[V] = SU;
+ }
+ // Handle the uses in MemUses, if there are any.
+ std::map<const Value *, std::vector<SUnit *> >::iterator J =
+ ((MayAlias) ? AliasMemUses.find(V) : NonAliasMemUses.find(V));
+ std::map<const Value *, std::vector<SUnit *> >::iterator JE =
+ ((MayAlias) ? AliasMemUses.end() : NonAliasMemUses.end());
+ if (J != JE) {
+ for (unsigned i = 0, e = J->second.size(); i != e; ++i)
+ J->second[i]->addPred(SDep(SU, SDep::Order, TrueMemOrderLatency,
+ /*Reg=*/0, /*isNormalMemory=*/true));
+ J->second.clear();
+ }
+ if (MayAlias) {
+ // Add dependencies from all the PendingLoads, i.e. loads
+ // with no underlying object.
+ for (unsigned k = 0, m = PendingLoads.size(); k != m; ++k)
+ PendingLoads[k]->addPred(SDep(SU, SDep::Order, TrueMemOrderLatency));
+ // Add dependence on alias chain, if needed.
+ if (AliasChain)
+ AliasChain->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ }
+ // Add dependence on barrier chain, if needed.
+ if (BarrierChain)
+ BarrierChain->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ } else {
+ // Treat all other stores conservatively.
+ goto new_alias_chain;
+ }
+ } else if (TID.mayLoad()) {
+ bool MayAlias = true;
+ TrueMemOrderLatency = 0;
+ if (MI->isInvariantLoad(AA)) {
+ // Invariant load, no chain dependencies needed!
+ } else {
+ if (const Value *V =
+ getUnderlyingObjectForInstr(MI, MFI, MayAlias)) {
+ // A load from a specific PseudoSourceValue. Add precise dependencies.
+ std::map<const Value *, SUnit *>::iterator I =
+ ((MayAlias) ? AliasMemDefs.find(V) : NonAliasMemDefs.find(V));
+ std::map<const Value *, SUnit *>::iterator IE =
+ ((MayAlias) ? AliasMemDefs.end() : NonAliasMemDefs.end());
+ if (I != IE)
+ I->second->addPred(SDep(SU, SDep::Order, /*Latency=*/0, /*Reg=*/0,
+ /*isNormalMemory=*/true));
+ if (MayAlias)
+ AliasMemUses[V].push_back(SU);
+ else
+ NonAliasMemUses[V].push_back(SU);
+ } else {
+ // A load with no underlying object. Depend on all
+ // potentially aliasing stores.
+ for (std::map<const Value *, SUnit *>::iterator I =
+ AliasMemDefs.begin(), E = AliasMemDefs.end(); I != E; ++I)
+ I->second->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+
+ PendingLoads.push_back(SU);
+ MayAlias = true;
+ }
+
+ // Add dependencies on alias and barrier chains, if needed.
+ if (MayAlias && AliasChain)
+ AliasChain->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ if (BarrierChain)
+ BarrierChain->addPred(SDep(SU, SDep::Order, /*Latency=*/0));
+ }
}
- if (Terminator && SU->Succs.empty())
- Terminator->addPred(SU, /*isCtrl=*/false, /*isSpecial=*/false);
- if (MI->getDesc().isTerminator() || MI->isLabel())
- Terminator = SU;
+ }
- // Assign the Latency field of SU using target-provided information.
- ComputeLatency(SU);
+ for (int i = 0, e = TRI->getNumRegs(); i != e; ++i) {
+ Defs[i].clear();
+ Uses[i].clear();
}
+ PendingLoads.clear();
+}
+
+void ScheduleDAGInstrs::FinishBlock() {
+ // Nothing to do.
}
void ScheduleDAGInstrs::ComputeLatency(SUnit *SU) {
const InstrItineraryData &InstrItins = TM.getInstrItineraryData();
- // Compute the latency for the node. We use the sum of the latencies for
- // all nodes flagged together into this SUnit.
+ // Compute the latency for the node.
SU->Latency =
- InstrItins.getLatency(SU->getInstr()->getDesc().getSchedClass());
+ InstrItins.getStageLatency(SU->getInstr()->getDesc().getSchedClass());
+
+ // Simplistic target-independent heuristic: assume that loads take
+ // extra time.
+ if (InstrItins.isEmpty())
+ if (SU->getInstr()->getDesc().mayLoad())
+ SU->Latency += 2;
+}
+
+void ScheduleDAGInstrs::ComputeOperandLatency(SUnit *Def, SUnit *Use,
+ SDep& dep) const {
+ const InstrItineraryData &InstrItins = TM.getInstrItineraryData();
+ if (InstrItins.isEmpty())
+ return;
+
+ // For a data dependency with a known register...
+ if ((dep.getKind() != SDep::Data) || (dep.getReg() == 0))
+ return;
+
+ const unsigned Reg = dep.getReg();
+
+ // ... find the definition of the register in the defining
+ // instruction
+ MachineInstr *DefMI = Def->getInstr();
+ int DefIdx = DefMI->findRegisterDefOperandIdx(Reg);
+ if (DefIdx != -1) {
+ int DefCycle = InstrItins.getOperandCycle(DefMI->getDesc().getSchedClass(),
+ DefIdx);
+ if (DefCycle >= 0) {
+ MachineInstr *UseMI = Use->getInstr();
+ const unsigned UseClass = UseMI->getDesc().getSchedClass();
+
+ // For all uses of the register, calculate the maxmimum latency
+ int Latency = -1;
+ for (unsigned i = 0, e = UseMI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = UseMI->getOperand(i);
+ if (!MO.isReg() || !MO.isUse())
+ continue;
+ unsigned MOReg = MO.getReg();
+ if (MOReg != Reg)
+ continue;
+
+ int UseCycle = InstrItins.getOperandCycle(UseClass, i);
+ if (UseCycle >= 0)
+ Latency = std::max(Latency, DefCycle - UseCycle + 1);
+ }
+
+ // If we found a latency, then replace the existing dependence latency.
+ if (Latency >= 0)
+ dep.setLatency(Latency);
+ }
+ }
}
void ScheduleDAGInstrs::dumpNode(const SUnit *SU) const {
std::string ScheduleDAGInstrs::getGraphNodeLabel(const SUnit *SU) const {
std::string s;
raw_string_ostream oss(s);
- SU->getInstr()->print(oss);
+ if (SU == &EntrySU)
+ oss << "<entry>";
+ else if (SU == &ExitSU)
+ oss << "<exit>";
+ else
+ SU->getInstr()->print(oss);
return oss.str();
}
MachineBasicBlock *ScheduleDAGInstrs::EmitSchedule() {
// For MachineInstr-based scheduling, we're rescheduling the instructions in
// the block, so start by removing them from the block.
- while (!BB->empty())
- BB->remove(BB->begin());
+ while (Begin != InsertPos) {
+ MachineBasicBlock::iterator I = Begin;
+ ++Begin;
+ BB->remove(I);
+ }
+
+ // First reinsert any remaining debug_values; these are either constants,
+ // or refer to live-in registers. The beginning of the block is the right
+ // place for the latter. The former might reasonably be placed elsewhere
+ // using some kind of ordering algorithm, but right now it doesn't matter.
+ for (int i = DbgValueVec.size()-1; i>=0; --i)
+ if (DbgValueVec[i])
+ BB->insert(InsertPos, DbgValueVec[i]);
+ // Then re-insert them according to the given schedule.
for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
SUnit *SU = Sequence[i];
if (!SU) {
continue;
}
- BB->push_back(SU->getInstr());
+ BB->insert(InsertPos, SU->getInstr());
+ for (unsigned i = 0, e = SU->DbgInstrList.size() ; i < e ; ++i)
+ BB->insert(InsertPos, SU->DbgInstrList[i]);
}
+ // Update the Begin iterator, as the first instruction in the block
+ // may have been scheduled later.
+ if (!DbgValueVec.empty()) {
+ for (int i = DbgValueVec.size()-1; i>=0; --i)
+ if (DbgValueVec[i]!=0) {
+ Begin = DbgValueVec[DbgValueVec.size()-1];
+ break;
+ }
+ } else if (!Sequence.empty())
+ Begin = Sequence[0]->getInstr();
+
+ DbgValueVec.clear();
return BB;
}
projects / oota-llvm.git / blobdiff