//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "post-RA-sched"
-#include "ExactHazardRecognizer.h"
-#include "SimpleHazardRecognizer.h"
-#include "ScheduleDAGInstrs.h"
+#include "AntiDepBreaker.h"
+#include "AggressiveAntiDepBreaker.h"
+#include "CriticalAntiDepBreaker.h"
+#include "RegisterClassInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/LatencyPriorityQueue.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/ScheduleDAGInstrs.h"
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/Statistic.h"
-#include <map>
-#include <set>
using namespace llvm;
STATISTIC(NumNoops, "Number of noops inserted");
STATISTIC(NumStalls, "Number of pipeline stalls");
+STATISTIC(NumFixedAnti, "Number of fixed anti-dependencies");
+// Post-RA scheduling is enabled with
+// TargetSubtargetInfo.enablePostRAScheduler(). This flag can be used to
+// override the target.
static cl::opt<bool>
+EnablePostRAScheduler("post-RA-scheduler",
+ cl::desc("Enable scheduling after register allocation"),
+ cl::init(false), cl::Hidden);
+static cl::opt<std::string>
EnableAntiDepBreaking("break-anti-dependencies",
- cl::desc("Break post-RA scheduling anti-dependencies"),
- cl::init(true), cl::Hidden);
-
-static cl::opt<bool>
-EnablePostRAHazardAvoidance("avoid-hazards",
- cl::desc("Enable exact hazard avoidance"),
- cl::init(false), cl::Hidden);
+ cl::desc("Break post-RA scheduling anti-dependencies: "
+ "\"critical\", \"all\", or \"none\""),
+ cl::init("none"), cl::Hidden);
// If DebugDiv > 0 then only schedule MBB with (ID % DebugDiv) == DebugMod
static cl::opt<int>
cl::desc("Debug control MBBs that are scheduled"),
cl::init(0), cl::Hidden);
+AntiDepBreaker::~AntiDepBreaker() { }
+
namespace {
- class VISIBILITY_HIDDEN PostRAScheduler : public MachineFunctionPass {
+ class PostRAScheduler : public MachineFunctionPass {
+ AliasAnalysis *AA;
+ const TargetInstrInfo *TII;
+ RegisterClassInfo RegClassInfo;
+
public:
static char ID;
- PostRAScheduler() : MachineFunctionPass(&ID) {}
+ PostRAScheduler() : MachineFunctionPass(ID) {}
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
+ AU.addRequired<AliasAnalysis>();
+ AU.addRequired<TargetPassConfig>();
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
AU.addRequired<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
- const char *getPassName() const {
- return "Post RA top-down list latency scheduler";
- }
-
bool runOnMachineFunction(MachineFunction &Fn);
};
char PostRAScheduler::ID = 0;
- class VISIBILITY_HIDDEN SchedulePostRATDList : public ScheduleDAGInstrs {
+ class SchedulePostRATDList : public ScheduleDAGInstrs {
/// AvailableQueue - The priority queue to use for the available SUnits.
///
LatencyPriorityQueue 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
/// Topo - A topological ordering for SUnits.
ScheduleDAGTopologicalSort Topo;
- /// AllocatableSet - The set of allocatable registers.
- /// We'll be ignoring anti-dependencies on non-allocatable registers,
- /// because they may not be safe to break.
- const BitVector AllocatableSet;
-
/// HazardRec - The hazard recognizer to use.
ScheduleHazardRecognizer *HazardRec;
- /// Classes - For live regs that are only used in one register class in a
- /// live range, the register class. If the register is not live, the
- /// corresponding value is null. If the register is live but used in
- /// multiple register classes, the corresponding value is -1 casted to a
- /// pointer.
- const TargetRegisterClass *
- Classes[TargetRegisterInfo::FirstVirtualRegister];
+ /// AntiDepBreak - Anti-dependence breaking object, or NULL if none
+ AntiDepBreaker *AntiDepBreak;
- /// RegRegs - Map registers to all their references within a live range.
- std::multimap<unsigned, MachineOperand *> RegRefs;
+ /// AA - AliasAnalysis for making memory reference queries.
+ AliasAnalysis *AA;
- /// The index of the most recent kill (proceding bottom-up), or ~0u if
- /// the register is not live.
- unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister];
+ /// LiveRegs - true if the register is live.
+ BitVector LiveRegs;
- /// The index of the most recent complete def (proceding bottom up), or ~0u
- /// if the register is live.
- unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister];
+ /// The schedule. Null SUnit*'s represent noop instructions.
+ std::vector<SUnit*> Sequence;
public:
- SchedulePostRATDList(MachineFunction &MF,
- const MachineLoopInfo &MLI,
- const MachineDominatorTree &MDT,
- ScheduleHazardRecognizer *HR)
- : ScheduleDAGInstrs(MF, MLI, MDT), Topo(SUnits),
- AllocatableSet(TRI->getAllocatableSet(MF)),
- HazardRec(HR) {}
-
- ~SchedulePostRATDList() {
- delete HazardRec;
- }
+ SchedulePostRATDList(
+ MachineFunction &MF, MachineLoopInfo &MLI, MachineDominatorTree &MDT,
+ AliasAnalysis *AA, const RegisterClassInfo&,
+ TargetSubtargetInfo::AntiDepBreakMode AntiDepMode,
+ SmallVectorImpl<const TargetRegisterClass*> &CriticalPathRCs);
- /// StartBlock - Initialize register live-range state for scheduling in
+ ~SchedulePostRATDList();
+
+ /// startBlock - Initialize register live-range state for scheduling in
/// this block.
///
- void StartBlock(MachineBasicBlock *BB);
+ void startBlock(MachineBasicBlock *BB);
+
+ /// Initialize the scheduler state for the next scheduling region.
+ virtual void enterRegion(MachineBasicBlock *bb,
+ MachineBasicBlock::iterator begin,
+ MachineBasicBlock::iterator end,
+ unsigned endcount);
+
+ /// Notify that the scheduler has finished scheduling the current region.
+ virtual void exitRegion();
/// Schedule - Schedule the instruction range using list scheduling.
///
- void Schedule();
-
- /// FixupKills - Fix register kill flags that have been made
- /// invalid due to scheduling
- ///
- void FixupKills(MachineBasicBlock *MBB);
+ void schedule();
+
+ void EmitSchedule();
/// Observe - Update liveness information to account for the current
/// instruction, which will not be scheduled.
///
void Observe(MachineInstr *MI, unsigned Count);
- /// FinishBlock - Clean up register live-range state.
+ /// finishBlock - Clean up register live-range state.
///
- void FinishBlock();
+ void finishBlock();
- /// GenerateLivenessForKills - If true then generate Def/Kill
- /// information for use in updating register kill. If false then
- /// generate Def/Kill information for anti-dependence breaking.
- bool GenerateLivenessForKills;
+ /// FixupKills - Fix register kill flags that have been made
+ /// invalid due to scheduling
+ ///
+ void FixupKills(MachineBasicBlock *MBB);
private:
- void PrescanInstruction(MachineInstr *MI);
- void ScanInstruction(MachineInstr *MI, unsigned Count);
void ReleaseSucc(SUnit *SU, SDep *SuccEdge);
void ReleaseSuccessors(SUnit *SU);
void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
void ListScheduleTopDown();
- bool BreakAntiDependencies();
- unsigned findSuitableFreeRegister(unsigned AntiDepReg,
- unsigned LastNewReg,
- const TargetRegisterClass *);
+ void StartBlockForKills(MachineBasicBlock *BB);
+
+ // ToggleKillFlag - Toggle a register operand kill flag. Other
+ // adjustments may be made to the instruction if necessary. Return
+ // true if the operand has been deleted, false if not.
+ bool ToggleKillFlag(MachineInstr *MI, MachineOperand &MO);
+
+ void dumpSchedule() const;
};
}
-/// isSchedulingBoundary - Test if the given instruction should be
-/// considered a scheduling boundary. This primarily includes labels
-/// and terminators.
-///
-static bool isSchedulingBoundary(const MachineInstr *MI,
- const MachineFunction &MF) {
- // Terminators and labels can't be scheduled around.
- if (MI->getDesc().isTerminator() || MI->isLabel())
- return true;
-
- // Don't attempt to schedule around any instruction that modifies
- // a stack-oriented pointer, as it's unlikely to be profitable. This
- // saves compile time, because it doesn't require every single
- // stack slot reference to depend on the instruction that does the
- // modification.
- const TargetLowering &TLI = *MF.getTarget().getTargetLowering();
- if (MI->modifiesRegister(TLI.getStackPointerRegisterToSaveRestore()))
- return true;
+char &llvm::PostRASchedulerID = PostRAScheduler::ID;
+
+INITIALIZE_PASS(PostRAScheduler, "post-RA-sched",
+ "Post RA top-down list latency scheduler", false, false)
+
+SchedulePostRATDList::SchedulePostRATDList(
+ MachineFunction &MF, MachineLoopInfo &MLI, MachineDominatorTree &MDT,
+ AliasAnalysis *AA, const RegisterClassInfo &RCI,
+ TargetSubtargetInfo::AntiDepBreakMode AntiDepMode,
+ SmallVectorImpl<const TargetRegisterClass*> &CriticalPathRCs)
+ : ScheduleDAGInstrs(MF, MLI, MDT, /*IsPostRA=*/true), Topo(SUnits), AA(AA),
+ LiveRegs(TRI->getNumRegs())
+{
+ const TargetMachine &TM = MF.getTarget();
+ const InstrItineraryData *InstrItins = TM.getInstrItineraryData();
+ HazardRec =
+ TM.getInstrInfo()->CreateTargetPostRAHazardRecognizer(InstrItins, this);
+ AntiDepBreak =
+ ((AntiDepMode == TargetSubtargetInfo::ANTIDEP_ALL) ?
+ (AntiDepBreaker *)new AggressiveAntiDepBreaker(MF, RCI, CriticalPathRCs) :
+ ((AntiDepMode == TargetSubtargetInfo::ANTIDEP_CRITICAL) ?
+ (AntiDepBreaker *)new CriticalAntiDepBreaker(MF, RCI) : NULL));
+}
- return false;
+SchedulePostRATDList::~SchedulePostRATDList() {
+ delete HazardRec;
+ delete AntiDepBreak;
+}
+
+/// Initialize state associated with the next scheduling region.
+void SchedulePostRATDList::enterRegion(MachineBasicBlock *bb,
+ MachineBasicBlock::iterator begin,
+ MachineBasicBlock::iterator end,
+ unsigned endcount) {
+ ScheduleDAGInstrs::enterRegion(bb, begin, end, endcount);
+ Sequence.clear();
+}
+
+/// Print the schedule before exiting the region.
+void SchedulePostRATDList::exitRegion() {
+ DEBUG({
+ dbgs() << "*** Final schedule ***\n";
+ dumpSchedule();
+ dbgs() << '\n';
+ });
+ ScheduleDAGInstrs::exitRegion();
+}
+
+/// dumpSchedule - dump the scheduled Sequence.
+void SchedulePostRATDList::dumpSchedule() const {
+ for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
+ if (SUnit *SU = Sequence[i])
+ SU->dump(this);
+ else
+ dbgs() << "**** NOOP ****\n";
+ }
}
bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
- DEBUG(errs() << "PostRAScheduler\n");
+ TII = Fn.getTarget().getInstrInfo();
+ MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
+ MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
+ AliasAnalysis *AA = &getAnalysis<AliasAnalysis>();
+ TargetPassConfig *PassConfig = &getAnalysis<TargetPassConfig>();
+
+ RegClassInfo.runOnMachineFunction(Fn);
+
+ // Check for explicit enable/disable of post-ra scheduling.
+ TargetSubtargetInfo::AntiDepBreakMode AntiDepMode =
+ TargetSubtargetInfo::ANTIDEP_NONE;
+ SmallVector<const TargetRegisterClass*, 4> CriticalPathRCs;
+ if (EnablePostRAScheduler.getPosition() > 0) {
+ if (!EnablePostRAScheduler)
+ return false;
+ } else {
+ // Check that post-RA scheduling is enabled for this target.
+ // This may upgrade the AntiDepMode.
+ const TargetSubtargetInfo &ST = Fn.getTarget().getSubtarget<TargetSubtargetInfo>();
+ if (!ST.enablePostRAScheduler(PassConfig->getOptLevel(), AntiDepMode,
+ CriticalPathRCs))
+ return false;
+ }
+
+ // Check for antidep breaking override...
+ if (EnableAntiDepBreaking.getPosition() > 0) {
+ AntiDepMode = (EnableAntiDepBreaking == "all")
+ ? TargetSubtargetInfo::ANTIDEP_ALL
+ : ((EnableAntiDepBreaking == "critical")
+ ? TargetSubtargetInfo::ANTIDEP_CRITICAL
+ : TargetSubtargetInfo::ANTIDEP_NONE);
+ }
- const MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
- const MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
- const InstrItineraryData &InstrItins = Fn.getTarget().getInstrItineraryData();
- ScheduleHazardRecognizer *HR = EnablePostRAHazardAvoidance ?
- (ScheduleHazardRecognizer *)new ExactHazardRecognizer(InstrItins) :
- (ScheduleHazardRecognizer *)new SimpleHazardRecognizer();
+ DEBUG(dbgs() << "PostRAScheduler\n");
- SchedulePostRATDList Scheduler(Fn, MLI, MDT, HR);
+ SchedulePostRATDList Scheduler(Fn, MLI, MDT, AA, RegClassInfo, AntiDepMode,
+ CriticalPathRCs);
// Loop over all of the basic blocks
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
static int bbcnt = 0;
if (bbcnt++ % DebugDiv != DebugMod)
continue;
- errs() << "*** DEBUG scheduling " << Fn.getFunction()->getNameStr() <<
- ":MBB ID#" << MBB->getNumber() << " ***\n";
+ dbgs() << "*** DEBUG scheduling " << Fn.getFunction()->getName()
+ << ":BB#" << MBB->getNumber() << " ***\n";
}
#endif
// Initialize register live-range state for scheduling in this block.
- Scheduler.GenerateLivenessForKills = false;
- Scheduler.StartBlock(MBB);
+ Scheduler.startBlock(MBB);
// Schedule each sequence of instructions not interrupted by a label
// or anything else that effectively needs to shut down scheduling.
MachineBasicBlock::iterator Current = MBB->end();
unsigned Count = MBB->size(), CurrentCount = Count;
for (MachineBasicBlock::iterator I = Current; I != MBB->begin(); ) {
- MachineInstr *MI = prior(I);
- if (isSchedulingBoundary(MI, Fn)) {
- Scheduler.Run(MBB, I, Current, CurrentCount);
+ MachineInstr *MI = llvm::prior(I);
+ // Calls are not scheduling boundaries before register allocation, but
+ // post-ra we don't gain anything by scheduling across calls since we
+ // don't need to worry about register pressure.
+ if (MI->isCall() || TII->isSchedulingBoundary(MI, MBB, Fn)) {
+ Scheduler.enterRegion(MBB, I, Current, CurrentCount);
+ Scheduler.schedule();
+ Scheduler.exitRegion();
Scheduler.EmitSchedule();
Current = MI;
CurrentCount = Count - 1;
}
I = MI;
--Count;
+ if (MI->isBundle())
+ Count -= MI->getBundleSize();
}
assert(Count == 0 && "Instruction count mismatch!");
assert((MBB->begin() == Current || CurrentCount != 0) &&
"Instruction count mismatch!");
- Scheduler.Run(MBB, MBB->begin(), Current, CurrentCount);
+ Scheduler.enterRegion(MBB, MBB->begin(), Current, CurrentCount);
+ Scheduler.schedule();
+ Scheduler.exitRegion();
Scheduler.EmitSchedule();
// Clean up register live-range state.
- Scheduler.FinishBlock();
+ Scheduler.finishBlock();
- // Initialize register live-range state again and update register kills
- Scheduler.GenerateLivenessForKills = true;
- Scheduler.StartBlock(MBB);
+ // Update register kills
Scheduler.FixupKills(MBB);
- Scheduler.FinishBlock();
}
return true;
}
-
+
/// StartBlock - Initialize register live-range state for scheduling in
/// this block.
///
-void SchedulePostRATDList::StartBlock(MachineBasicBlock *BB) {
+void SchedulePostRATDList::startBlock(MachineBasicBlock *BB) {
// Call the superclass.
- ScheduleDAGInstrs::StartBlock(BB);
+ ScheduleDAGInstrs::startBlock(BB);
- // Reset the hazard recognizer.
+ // Reset the hazard recognizer and anti-dep breaker.
HazardRec->Reset();
-
- // Clear out the register class data.
- std::fill(Classes, array_endof(Classes),
- static_cast<const TargetRegisterClass *>(0));
-
- // Initialize the indices to indicate that no registers are live.
- std::fill(KillIndices, array_endof(KillIndices), ~0u);
- std::fill(DefIndices, array_endof(DefIndices), BB->size());
-
- // Determine the live-out physregs for this block.
- if (!BB->empty() && BB->back().getDesc().isReturn())
- // In a return block, examine the function live-out regs.
- for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(),
- E = MRI.liveout_end(); I != E; ++I) {
- unsigned Reg = *I;
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[Reg] = BB->size();
- DefIndices[Reg] = ~0u;
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[AliasReg] = BB->size();
- DefIndices[AliasReg] = ~0u;
- }
- }
- else
- // In a non-return block, examine the live-in regs of all successors.
- for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
- SE = BB->succ_end(); SI != SE; ++SI)
- for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(),
- E = (*SI)->livein_end(); I != E; ++I) {
- unsigned Reg = *I;
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[Reg] = BB->size();
- DefIndices[Reg] = ~0u;
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[AliasReg] = BB->size();
- DefIndices[AliasReg] = ~0u;
- }
- }
-
- if (!GenerateLivenessForKills) {
- // Consider callee-saved registers as live-out, since we're running after
- // prologue/epilogue insertion so there's no way to add additional
- // saved registers.
- //
- // TODO: there is a new method
- // MachineFrameInfo::getPristineRegs(MBB). It gives you a list of
- // CSRs that have not been saved when entering the MBB. The
- // remaining CSRs have been saved and can be treated like call
- // clobbered registers.
- for (const unsigned *I = TRI->getCalleeSavedRegs(); *I; ++I) {
- unsigned Reg = *I;
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[Reg] = BB->size();
- DefIndices[Reg] = ~0u;
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- KillIndices[AliasReg] = BB->size();
- DefIndices[AliasReg] = ~0u;
- }
- }
- }
+ if (AntiDepBreak != NULL)
+ AntiDepBreak->StartBlock(BB);
}
/// Schedule - Schedule the instruction range using list scheduling.
///
-void SchedulePostRATDList::Schedule() {
- DEBUG(errs() << "********** List Scheduling **********\n");
-
+void SchedulePostRATDList::schedule() {
// Build the scheduling graph.
- BuildSchedGraph();
+ buildSchedGraph(AA);
- if (EnableAntiDepBreaking) {
- if (BreakAntiDependencies()) {
+ if (AntiDepBreak != NULL) {
+ unsigned Broken =
+ AntiDepBreak->BreakAntiDependencies(SUnits, RegionBegin, RegionEnd,
+ EndIndex, DbgValues);
+
+ if (Broken != 0) {
// We made changes. Update the dependency graph.
// Theoretically we could update the graph in place:
// When a live range is changed to use a different register, remove
// the def's anti-dependence *and* output-dependence edges due to
// that register, and add new anti-dependence and output-dependence
// edges based on the next live range of the register.
- SUnits.clear();
- EntrySU = SUnit();
- ExitSU = SUnit();
- BuildSchedGraph();
+ ScheduleDAG::clearDAG();
+ buildSchedGraph(AA);
+
+ NumFixedAnti += Broken;
}
}
+ DEBUG(dbgs() << "********** List Scheduling **********\n");
DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
SUnits[su].dumpAll(this));
AvailableQueue.initNodes(SUnits);
-
ListScheduleTopDown();
-
AvailableQueue.releaseState();
}
/// instruction, which will not be scheduled.
///
void SchedulePostRATDList::Observe(MachineInstr *MI, unsigned Count) {
- assert(Count < InsertPosIndex && "Instruction index out of expected range!");
-
- // Any register which was defined within the previous scheduling region
- // may have been rescheduled and its lifetime may overlap with registers
- // in ways not reflected in our current liveness state. For each such
- // register, adjust the liveness state to be conservatively correct.
- for (unsigned Reg = 0; Reg != TargetRegisterInfo::FirstVirtualRegister; ++Reg)
- if (DefIndices[Reg] < InsertPosIndex && DefIndices[Reg] >= Count) {
- assert(KillIndices[Reg] == ~0u && "Clobbered register is live!");
- // Mark this register to be non-renamable.
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- // Move the def index to the end of the previous region, to reflect
- // that the def could theoretically have been scheduled at the end.
- DefIndices[Reg] = InsertPosIndex;
- }
-
- PrescanInstruction(MI);
- ScanInstruction(MI, Count);
+ if (AntiDepBreak != NULL)
+ AntiDepBreak->Observe(MI, Count, EndIndex);
}
/// FinishBlock - Clean up register live-range state.
///
-void SchedulePostRATDList::FinishBlock() {
- RegRefs.clear();
+void SchedulePostRATDList::finishBlock() {
+ if (AntiDepBreak != NULL)
+ AntiDepBreak->FinishBlock();
// Call the superclass.
- ScheduleDAGInstrs::FinishBlock();
+ ScheduleDAGInstrs::finishBlock();
}
-/// CriticalPathStep - Return the next SUnit after SU on the bottom-up
-/// critical path.
-static SDep *CriticalPathStep(SUnit *SU) {
- SDep *Next = 0;
- unsigned NextDepth = 0;
- // Find the predecessor edge with the greatest depth.
- for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end();
- P != PE; ++P) {
- SUnit *PredSU = P->getSUnit();
- unsigned PredLatency = P->getLatency();
- unsigned PredTotalLatency = PredSU->getDepth() + PredLatency;
- // In the case of a latency tie, prefer an anti-dependency edge over
- // other types of edges.
- if (NextDepth < PredTotalLatency ||
- (NextDepth == PredTotalLatency && P->getKind() == SDep::Anti)) {
- NextDepth = PredTotalLatency;
- Next = &*P;
- }
- }
- return Next;
-}
-
-void SchedulePostRATDList::PrescanInstruction(MachineInstr *MI) {
- // Scan the register operands for this instruction and update
- // Classes and RegRefs.
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg()) continue;
- unsigned Reg = MO.getReg();
- if (Reg == 0) continue;
- const TargetRegisterClass *NewRC = 0;
-
- if (i < MI->getDesc().getNumOperands())
- NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI);
-
- // For now, only allow the register to be changed if its register
- // class is consistent across all uses.
- if (!Classes[Reg] && NewRC)
- Classes[Reg] = NewRC;
- else if (!NewRC || Classes[Reg] != NewRC)
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
-
- // Now check for aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- // If an alias of the reg is used during the live range, give up.
- // Note that this allows us to skip checking if AntiDepReg
- // overlaps with any of the aliases, among other things.
- unsigned AliasReg = *Alias;
- if (Classes[AliasReg]) {
- Classes[AliasReg] = reinterpret_cast<TargetRegisterClass *>(-1);
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
- }
- }
-
- // If we're still willing to consider this register, note the reference.
- if (Classes[Reg] != reinterpret_cast<TargetRegisterClass *>(-1))
- RegRefs.insert(std::make_pair(Reg, &MO));
- }
-}
+/// StartBlockForKills - Initialize register live-range state for updating kills
+///
+void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) {
+ // Start with no live registers.
+ LiveRegs.reset();
-void SchedulePostRATDList::ScanInstruction(MachineInstr *MI,
- unsigned Count) {
- // Update liveness.
- // Proceding upwards, registers that are defed but not used in this
- // instruction are now dead.
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg()) continue;
- unsigned Reg = MO.getReg();
- if (Reg == 0) continue;
- if (!MO.isDef()) continue;
- // Ignore two-addr defs.
- if (MI->isRegTiedToUseOperand(i)) continue;
-
- DefIndices[Reg] = Count;
- KillIndices[Reg] = ~0u;
- assert(((KillIndices[Reg] == ~0u) !=
- (DefIndices[Reg] == ~0u)) &&
- "Kill and Def maps aren't consistent for Reg!");
- Classes[Reg] = 0;
- RegRefs.erase(Reg);
- // Repeat, for all subregs.
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- unsigned SubregReg = *Subreg;
- DefIndices[SubregReg] = Count;
- KillIndices[SubregReg] = ~0u;
- Classes[SubregReg] = 0;
- RegRefs.erase(SubregReg);
- }
- // Conservatively mark super-registers as unusable.
- for (const unsigned *Super = TRI->getSuperRegisters(Reg);
- *Super; ++Super) {
- unsigned SuperReg = *Super;
- Classes[SuperReg] = reinterpret_cast<TargetRegisterClass *>(-1);
+ // Determine the live-out physregs for this block.
+ if (!BB->empty() && BB->back().isReturn()) {
+ // In a return block, examine the function live-out regs.
+ for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(),
+ E = MRI.liveout_end(); I != E; ++I) {
+ unsigned Reg = *I;
+ LiveRegs.set(Reg);
+ // Repeat, for all subregs.
+ for (const uint16_t *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg)
+ LiveRegs.set(*Subreg);
}
}
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg()) continue;
- unsigned Reg = MO.getReg();
- if (Reg == 0) continue;
- if (!MO.isUse()) continue;
-
- const TargetRegisterClass *NewRC = 0;
- if (i < MI->getDesc().getNumOperands())
- NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI);
-
- // For now, only allow the register to be changed if its register
- // class is consistent across all uses.
- if (!Classes[Reg] && NewRC)
- Classes[Reg] = NewRC;
- else if (!NewRC || Classes[Reg] != NewRC)
- Classes[Reg] = reinterpret_cast<TargetRegisterClass *>(-1);
-
- RegRefs.insert(std::make_pair(Reg, &MO));
-
- // It wasn't previously live but now it is, this is a kill.
- if (KillIndices[Reg] == ~0u) {
- KillIndices[Reg] = Count;
- DefIndices[Reg] = ~0u;
- assert(((KillIndices[Reg] == ~0u) !=
- (DefIndices[Reg] == ~0u)) &&
- "Kill and Def maps aren't consistent for Reg!");
- }
- // Repeat, for all aliases.
- for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
- unsigned AliasReg = *Alias;
- if (KillIndices[AliasReg] == ~0u) {
- KillIndices[AliasReg] = Count;
- DefIndices[AliasReg] = ~0u;
+ else {
+ // In a non-return block, examine the live-in regs of all successors.
+ for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
+ SE = BB->succ_end(); SI != SE; ++SI) {
+ for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(),
+ E = (*SI)->livein_end(); I != E; ++I) {
+ unsigned Reg = *I;
+ LiveRegs.set(Reg);
+ // Repeat, for all subregs.
+ for (const uint16_t *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg)
+ LiveRegs.set(*Subreg);
}
}
}
}
-unsigned
-SchedulePostRATDList::findSuitableFreeRegister(unsigned AntiDepReg,
- unsigned LastNewReg,
- const TargetRegisterClass *RC) {
- for (TargetRegisterClass::iterator R = RC->allocation_order_begin(MF),
- RE = RC->allocation_order_end(MF); R != RE; ++R) {
- unsigned NewReg = *R;
- // Don't replace a register with itself.
- if (NewReg == AntiDepReg) continue;
- // Don't replace a register with one that was recently used to repair
- // an anti-dependence with this AntiDepReg, because that would
- // re-introduce that anti-dependence.
- if (NewReg == LastNewReg) continue;
- // If NewReg is dead and NewReg's most recent def is not before
- // AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg.
- assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u)) &&
- "Kill and Def maps aren't consistent for AntiDepReg!");
- assert(((KillIndices[NewReg] == ~0u) != (DefIndices[NewReg] == ~0u)) &&
- "Kill and Def maps aren't consistent for NewReg!");
- if (KillIndices[NewReg] != ~0u ||
- Classes[NewReg] == reinterpret_cast<TargetRegisterClass *>(-1) ||
- KillIndices[AntiDepReg] > DefIndices[NewReg])
- continue;
- return NewReg;
+bool SchedulePostRATDList::ToggleKillFlag(MachineInstr *MI,
+ MachineOperand &MO) {
+ // Setting kill flag...
+ if (!MO.isKill()) {
+ MO.setIsKill(true);
+ return false;
}
- // No registers are free and available!
- return 0;
-}
-
-/// BreakAntiDependencies - Identifiy anti-dependencies along the critical path
-/// of the ScheduleDAG and break them by renaming registers.
-///
-bool SchedulePostRATDList::BreakAntiDependencies() {
- // The code below assumes that there is at least one instruction,
- // so just duck out immediately if the block is empty.
- if (SUnits.empty()) return false;
-
- // Find the node at the bottom of the critical path.
- SUnit *Max = 0;
- for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
- SUnit *SU = &SUnits[i];
- if (!Max || SU->getDepth() + SU->Latency > Max->getDepth() + Max->Latency)
- Max = SU;
+ // If MO itself is live, clear the kill flag...
+ if (LiveRegs.test(MO.getReg())) {
+ MO.setIsKill(false);
+ return false;
}
- DEBUG(errs() << "Critical path has total latency "
- << (Max->getDepth() + Max->Latency) << "\n");
-
- // Track progress along the critical path through the SUnit graph as we walk
- // the instructions.
- SUnit *CriticalPathSU = Max;
- MachineInstr *CriticalPathMI = CriticalPathSU->getInstr();
-
- // Consider this pattern:
- // A = ...
- // ... = A
- // A = ...
- // ... = A
- // A = ...
- // ... = A
- // A = ...
- // ... = A
- // There are three anti-dependencies here, and without special care,
- // we'd break all of them using the same register:
- // A = ...
- // ... = A
- // B = ...
- // ... = B
- // B = ...
- // ... = B
- // B = ...
- // ... = B
- // because at each anti-dependence, B is the first register that
- // isn't A which is free. This re-introduces anti-dependencies
- // at all but one of the original anti-dependencies that we were
- // trying to break. To avoid this, keep track of the most recent
- // register that each register was replaced with, avoid
- // using it to repair an anti-dependence on the same register.
- // This lets us produce this:
- // A = ...
- // ... = A
- // B = ...
- // ... = B
- // C = ...
- // ... = C
- // B = ...
- // ... = B
- // This still has an anti-dependence on B, but at least it isn't on the
- // original critical path.
- //
- // TODO: If we tracked more than one register here, we could potentially
- // fix that remaining critical edge too. This is a little more involved,
- // because unlike the most recent register, less recent registers should
- // still be considered, though only if no other registers are available.
- unsigned LastNewReg[TargetRegisterInfo::FirstVirtualRegister] = {};
-
- // Attempt to break anti-dependence edges on the critical path. Walk the
- // instructions from the bottom up, tracking information about liveness
- // as we go to help determine which registers are available.
- bool Changed = false;
- unsigned Count = InsertPosIndex - 1;
- for (MachineBasicBlock::iterator I = InsertPos, E = Begin;
- I != E; --Count) {
- MachineInstr *MI = --I;
-
- // After regalloc, IMPLICIT_DEF instructions aren't safe to treat as
- // dependence-breaking. In the case of an INSERT_SUBREG, the IMPLICIT_DEF
- // is left behind appearing to clobber the super-register, while the
- // subregister needs to remain live. So we just ignore them.
- if (MI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
- continue;
-
- // Check if this instruction has a dependence on the critical path that
- // is an anti-dependence that we may be able to break. If it is, set
- // AntiDepReg to the non-zero register associated with the anti-dependence.
- //
- // We limit our attention to the critical path as a heuristic to avoid
- // breaking anti-dependence edges that aren't going to significantly
- // impact the overall schedule. There are a limited number of registers
- // and we want to save them for the important edges.
- //
- // TODO: Instructions with multiple defs could have multiple
- // anti-dependencies. The current code here only knows how to break one
- // edge per instruction. Note that we'd have to be able to break all of
- // the anti-dependencies in an instruction in order to be effective.
- unsigned AntiDepReg = 0;
- if (MI == CriticalPathMI) {
- if (SDep *Edge = CriticalPathStep(CriticalPathSU)) {
- SUnit *NextSU = Edge->getSUnit();
-
- // Only consider anti-dependence edges.
- if (Edge->getKind() == SDep::Anti) {
- AntiDepReg = Edge->getReg();
- assert(AntiDepReg != 0 && "Anti-dependence on reg0?");
- // Don't break anti-dependencies on non-allocatable registers.
- if (!AllocatableSet.test(AntiDepReg))
- AntiDepReg = 0;
- else {
- // If the SUnit has other dependencies on the SUnit that it
- // anti-depends on, don't bother breaking the anti-dependency
- // since those edges would prevent such units from being
- // scheduled past each other regardless.
- //
- // Also, if there are dependencies on other SUnits with the
- // same register as the anti-dependency, don't attempt to
- // break it.
- for (SUnit::pred_iterator P = CriticalPathSU->Preds.begin(),
- PE = CriticalPathSU->Preds.end(); P != PE; ++P)
- if (P->getSUnit() == NextSU ?
- (P->getKind() != SDep::Anti || P->getReg() != AntiDepReg) :
- (P->getKind() == SDep::Data && P->getReg() == AntiDepReg)) {
- AntiDepReg = 0;
- break;
- }
- }
- }
- CriticalPathSU = NextSU;
- CriticalPathMI = CriticalPathSU->getInstr();
- } else {
- // We've reached the end of the critical path.
- CriticalPathSU = 0;
- CriticalPathMI = 0;
- }
- }
-
- PrescanInstruction(MI);
-
- // If this instruction has a use of AntiDepReg, breaking it
- // is invalid.
- for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.isReg()) continue;
- unsigned Reg = MO.getReg();
- if (Reg == 0) continue;
- if (MO.isUse() && AntiDepReg == Reg) {
- AntiDepReg = 0;
- break;
- }
- }
-
- // Determine AntiDepReg's register class, if it is live and is
- // consistently used within a single class.
- const TargetRegisterClass *RC = AntiDepReg != 0 ? Classes[AntiDepReg] : 0;
- assert((AntiDepReg == 0 || RC != NULL) &&
- "Register should be live if it's causing an anti-dependence!");
- if (RC == reinterpret_cast<TargetRegisterClass *>(-1))
- AntiDepReg = 0;
-
- // Look for a suitable register to use to break the anti-depenence.
- //
- // TODO: Instead of picking the first free register, consider which might
- // be the best.
- if (AntiDepReg != 0) {
- if (unsigned NewReg = findSuitableFreeRegister(AntiDepReg,
- LastNewReg[AntiDepReg],
- RC)) {
- DEBUG(errs() << "Breaking anti-dependence edge on "
- << TRI->getName(AntiDepReg)
- << " with " << RegRefs.count(AntiDepReg) << " references"
- << " using " << TRI->getName(NewReg) << "!\n");
-
- // Update the references to the old register to refer to the new
- // register.
- std::pair<std::multimap<unsigned, MachineOperand *>::iterator,
- std::multimap<unsigned, MachineOperand *>::iterator>
- Range = RegRefs.equal_range(AntiDepReg);
- for (std::multimap<unsigned, MachineOperand *>::iterator
- Q = Range.first, QE = Range.second; Q != QE; ++Q)
- Q->second->setReg(NewReg);
-
- // We just went back in time and modified history; the
- // liveness information for the anti-depenence reg is now
- // inconsistent. Set the state as if it were dead.
- Classes[NewReg] = Classes[AntiDepReg];
- DefIndices[NewReg] = DefIndices[AntiDepReg];
- KillIndices[NewReg] = KillIndices[AntiDepReg];
- assert(((KillIndices[NewReg] == ~0u) !=
- (DefIndices[NewReg] == ~0u)) &&
- "Kill and Def maps aren't consistent for NewReg!");
-
- Classes[AntiDepReg] = 0;
- DefIndices[AntiDepReg] = KillIndices[AntiDepReg];
- KillIndices[AntiDepReg] = ~0u;
- assert(((KillIndices[AntiDepReg] == ~0u) !=
- (DefIndices[AntiDepReg] == ~0u)) &&
- "Kill and Def maps aren't consistent for AntiDepReg!");
-
- RegRefs.erase(AntiDepReg);
- Changed = true;
- LastNewReg[AntiDepReg] = NewReg;
- }
+ // If any subreg of MO is live, then create an imp-def for that
+ // subreg and keep MO marked as killed.
+ MO.setIsKill(false);
+ bool AllDead = true;
+ const unsigned SuperReg = MO.getReg();
+ for (const uint16_t *Subreg = TRI->getSubRegisters(SuperReg);
+ *Subreg; ++Subreg) {
+ if (LiveRegs.test(*Subreg)) {
+ MI->addOperand(MachineOperand::CreateReg(*Subreg,
+ true /*IsDef*/,
+ true /*IsImp*/,
+ false /*IsKill*/,
+ false /*IsDead*/));
+ AllDead = false;
}
-
- ScanInstruction(MI, Count);
}
- return Changed;
+ if(AllDead)
+ MO.setIsKill(true);
+ return false;
}
/// FixupKills - Fix the register kill flags, they may have been made
/// incorrect by instruction reordering.
///
void SchedulePostRATDList::FixupKills(MachineBasicBlock *MBB) {
- DEBUG(errs() << "Fixup kills for BB ID#" << MBB->getNumber() << '\n');
+ DEBUG(dbgs() << "Fixup kills for BB#" << MBB->getNumber() << '\n');
- std::set<unsigned> killedRegs;
+ BitVector killedRegs(TRI->getNumRegs());
BitVector ReservedRegs = TRI->getReservedRegs(MF);
-
+
+ StartBlockForKills(MBB);
+
// Examine block from end to start...
unsigned Count = MBB->size();
for (MachineBasicBlock::iterator I = MBB->end(), E = MBB->begin();
I != E; --Count) {
MachineInstr *MI = --I;
+ if (MI->isDebugValue())
+ continue;
// Update liveness. Registers that are defed but not used in this
// instruction are now dead. Mark register and all subregs as they
// are completely defined.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
+ if (MO.isRegMask())
+ LiveRegs.clearBitsNotInMask(MO.getRegMask());
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
if (!MO.isDef()) continue;
// Ignore two-addr defs.
if (MI->isRegTiedToUseOperand(i)) continue;
-
- KillIndices[Reg] = ~0u;
-
+
+ LiveRegs.reset(Reg);
+
// Repeat for all subregs.
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- KillIndices[*Subreg] = ~0u;
- }
+ for (const uint16_t *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg)
+ LiveRegs.reset(*Subreg);
}
- // Examine all used registers and set kill flag. When a register
- // is used multiple times we only set the kill flag on the first
- // use.
- killedRegs.clear();
+ // Examine all used registers and set/clear kill flag. When a
+ // register is used multiple times we only set the kill flag on
+ // the first use.
+ killedRegs.reset();
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isUse()) continue;
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
bool kill = false;
- if (killedRegs.find(Reg) == killedRegs.end()) {
+ if (!killedRegs.test(Reg)) {
kill = true;
// A register is not killed if any subregs are live...
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
+ for (const uint16_t *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
- if (KillIndices[*Subreg] != ~0u) {
+ if (LiveRegs.test(*Subreg)) {
kill = false;
break;
}
// If subreg is not live, then register is killed if it became
// live in this instruction
if (kill)
- kill = (KillIndices[Reg] == ~0u);
+ kill = !LiveRegs.test(Reg);
}
-
+
if (MO.isKill() != kill) {
- MO.setIsKill(kill);
- DEBUG(errs() << "Fixed " << MO << " in ");
+ DEBUG(dbgs() << "Fixing " << MO << " in ");
+ // Warning: ToggleKillFlag may invalidate MO.
+ ToggleKillFlag(MI, MO);
DEBUG(MI->dump());
}
-
- killedRegs.insert(Reg);
+
+ killedRegs.set(Reg);
}
-
+
// Mark any used register (that is not using undef) and subregs as
// now live...
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
unsigned Reg = MO.getReg();
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
- KillIndices[Reg] = Count;
-
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- KillIndices[*Subreg] = Count;
- }
+ LiveRegs.set(Reg);
+
+ for (const uint16_t *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg)
+ LiveRegs.set(*Subreg);
}
}
}
/// the PendingQueue if the count reaches zero. Also update its cycle bound.
void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge) {
SUnit *SuccSU = SuccEdge->getSUnit();
- --SuccSU->NumPredsLeft;
-
+
#ifndef NDEBUG
- if (SuccSU->NumPredsLeft < 0) {
- errs() << "*** Scheduling failed! ***\n";
+ if (SuccSU->NumPredsLeft == 0) {
+ dbgs() << "*** Scheduling failed! ***\n";
SuccSU->dump(this);
- errs() << " has been released too many times!\n";
+ dbgs() << " has been released too many times!\n";
llvm_unreachable(0);
}
#endif
-
- // 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.
- SuccSU->setDepthToAtLeast(SU->getDepth() + SuccEdge->getLatency());
-
+ --SuccSU->NumPredsLeft;
+
+ // Standard scheduler algorithms will recompute the depth of the successor
+ // here as such:
+ // SuccSU->setDepthToAtLeast(SU->getDepth() + SuccEdge->getLatency());
+ //
+ // However, we lazily compute node depth instead. Note that
+ // ScheduleNodeTopDown has already updated the depth of this node which causes
+ // all descendents to be marked dirty. Setting the successor depth explicitly
+ // here would cause depth to be recomputed for all its ancestors. If the
+ // successor is not yet ready (because of a transitively redundant edge) then
+ // this causes depth computation to be quadratic in the size of the DAG.
+
// If all the node's predecessors are scheduled, this node is ready
// to be scheduled. Ignore the special ExitSU node.
if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU)
/// ReleaseSuccessors - Call ReleaseSucc on each of SU's successors.
void SchedulePostRATDList::ReleaseSuccessors(SUnit *SU) {
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
- I != E; ++I)
+ I != E; ++I) {
ReleaseSucc(SU, &*I);
+ }
}
/// 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 SchedulePostRATDList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
- DEBUG(errs() << "*** Scheduling [" << CurCycle << "]: ");
+ DEBUG(dbgs() << "*** Scheduling [" << CurCycle << "]: ");
DEBUG(SU->dump(this));
-
+
Sequence.push_back(SU);
- assert(CurCycle >= SU->getDepth() && "Node scheduled above its depth!");
+ assert(CurCycle >= SU->getDepth() &&
+ "Node scheduled above its depth!");
SU->setDepthToAtLeast(CurCycle);
ReleaseSuccessors(SU);
SU->isScheduled = true;
- AvailableQueue.ScheduledNode(SU);
+ AvailableQueue.scheduledNode(SU);
}
/// ListScheduleTopDown - The main loop of list scheduling for top-down
void SchedulePostRATDList::ListScheduleTopDown() {
unsigned CurCycle = 0;
+ // We're scheduling top-down but we're visiting the regions in
+ // bottom-up order, so we don't know the hazards at the start of a
+ // region. So assume no hazards (this should usually be ok as most
+ // blocks are a single region).
+ HazardRec->Reset();
+
// Release any successors of the special Entry node.
ReleaseSuccessors(&EntrySU);
- // All leaves to Available queue.
+ // Add 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()) {
+ bool available = SUnits[i].Preds.empty();
+ if (available) {
AvailableQueue.push(&SUnits[i]);
SUnits[i].isAvailable = true;
}
// In any cycle where we can't schedule any instructions, we must
// stall or emit a noop, depending on the target.
- bool CycleInstCnt = 0;
+ bool CycleHasInsts = false;
// While Available queue is not empty, grab the node with the highest
// priority. If it is not ready put it back. Schedule the node.
MinDepth = PendingQueue[i]->getDepth();
}
- DEBUG(errs() << "\n*** Examining Available\n";
- LatencyPriorityQueue q = AvailableQueue;
- while (!q.empty()) {
- SUnit *su = q.pop();
- errs() << "Height " << su->getHeight() << ": ";
- su->dump(this);
- });
+ DEBUG(dbgs() << "\n*** Examining Available\n"; AvailableQueue.dump(this));
SUnit *FoundSUnit = 0;
-
bool HasNoopHazards = false;
while (!AvailableQueue.empty()) {
SUnit *CurSUnit = AvailableQueue.pop();
ScheduleHazardRecognizer::HazardType HT =
- HazardRec->getHazardType(CurSUnit);
+ HazardRec->getHazardType(CurSUnit, 0/*no stalls*/);
if (HT == ScheduleHazardRecognizer::NoHazard) {
FoundSUnit = CurSUnit;
break;
NotReady.clear();
}
- // If we found a node to schedule, do it now.
+ // If we found a node to schedule...
if (FoundSUnit) {
+ // ... schedule the node...
ScheduleNodeTopDown(FoundSUnit, CurCycle);
HazardRec->EmitInstruction(FoundSUnit);
- CycleInstCnt++;
-
- // If we are using the target-specific hazards, then don't
- // advance the cycle time just because we schedule a node. If
- // the target allows it we can schedule multiple nodes in the
- // same cycle.
- if (!EnablePostRAHazardAvoidance) {
- if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops!
- ++CurCycle;
+ CycleHasInsts = true;
+ if (HazardRec->atIssueLimit()) {
+ DEBUG(dbgs() << "*** Max instructions per cycle " << CurCycle << '\n');
+ HazardRec->AdvanceCycle();
+ ++CurCycle;
+ CycleHasInsts = false;
}
} else {
- if (CycleInstCnt > 0) {
- DEBUG(errs() << "*** Finished cycle " << CurCycle << '\n');
+ if (CycleHasInsts) {
+ DEBUG(dbgs() << "*** Finished cycle " << CurCycle << '\n');
HazardRec->AdvanceCycle();
} else if (!HasNoopHazards) {
// Otherwise, we have a pipeline stall, but no other problem,
// just advance the current cycle and try again.
- DEBUG(errs() << "*** Stall in cycle " << CurCycle << '\n');
+ DEBUG(dbgs() << "*** Stall in cycle " << CurCycle << '\n');
HazardRec->AdvanceCycle();
++NumStalls;
} 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.
- DEBUG(errs() << "*** Emitting noop in cycle " << CurCycle << '\n');
+ DEBUG(dbgs() << "*** Emitting noop in cycle " << CurCycle << '\n');
HazardRec->EmitNoop();
Sequence.push_back(0); // NULL here means noop
++NumNoops;
}
++CurCycle;
- CycleInstCnt = 0;
+ CycleHasInsts = false;
}
}
#ifndef NDEBUG
- VerifySchedule(/*isBottomUp=*/false);
-#endif
+ unsigned ScheduledNodes = VerifyScheduledDAG(/*isBottomUp=*/false);
+ unsigned Noops = 0;
+ for (unsigned i = 0, e = Sequence.size(); i != e; ++i)
+ if (!Sequence[i])
+ ++Noops;
+ assert(Sequence.size() - Noops == ScheduledNodes &&
+ "The number of nodes scheduled doesn't match the expected number!");
+#endif // NDEBUG
}
-//===----------------------------------------------------------------------===//
-// Public Constructor Functions
-//===----------------------------------------------------------------------===//
+// EmitSchedule - Emit the machine code in scheduled order.
+void SchedulePostRATDList::EmitSchedule() {
+ RegionBegin = RegionEnd;
+
+ // If first instruction was a DBG_VALUE then put it back.
+ if (FirstDbgValue)
+ BB->splice(RegionEnd, BB, FirstDbgValue);
+
+ // Then re-insert them according to the given schedule.
+ for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
+ if (SUnit *SU = Sequence[i])
+ BB->splice(RegionEnd, BB, SU->getInstr());
+ else
+ // Null SUnit* is a noop.
+ TII->insertNoop(*BB, RegionEnd);
+
+ // Update the Begin iterator, as the first instruction in the block
+ // may have been scheduled later.
+ if (i == 0)
+ RegionBegin = prior(RegionEnd);
+ }
-FunctionPass *llvm::createPostRAScheduler() {
- return new PostRAScheduler();
+ // Reinsert any remaining debug_values.
+ for (std::vector<std::pair<MachineInstr *, MachineInstr *> >::iterator
+ DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) {
+ std::pair<MachineInstr *, MachineInstr *> P = *prior(DI);
+ MachineInstr *DbgValue = P.first;
+ MachineBasicBlock::iterator OrigPrivMI = P.second;
+ BB->splice(++OrigPrivMI, BB, DbgValue);
+ }
+ DbgValues.clear();
+ FirstDbgValue = NULL;
}
projects / oota-llvm.git / blobdiff