//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "post-RA-sched"
+#include "AntiDepBreaker.h"
#include "AggressiveAntiDepBreaker.h"
#include "CriticalAntiDepBreaker.h"
-#include "ExactHazardRecognizer.h"
-#include "SimpleHazardRecognizer.h"
+#include "RegisterClassInfo.h"
#include "ScheduleDAGInstrs.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/LatencyPriorityQueue.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Target/TargetSubtarget.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(NumFixedAnti, "Number of fixed anti-dependencies");
// Post-RA scheduling is enabled with
-// TargetSubtarget.enablePostRAScheduler(). This flag can be used to
+// TargetSubtargetInfo.enablePostRAScheduler(). This flag can be used to
// override the target.
static cl::opt<bool>
EnablePostRAScheduler("post-RA-scheduler",
cl::desc("Break post-RA scheduling anti-dependencies: "
"\"critical\", \"all\", or \"none\""),
cl::init("none"), cl::Hidden);
-static cl::opt<bool>
-EnablePostRAHazardAvoidance("avoid-hazards",
- cl::desc("Enable exact hazard avoidance"),
- cl::init(true), 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 PostRAScheduler : public MachineFunctionPass {
AliasAnalysis *AA;
+ const TargetInstrInfo *TII;
+ RegisterClassInfo RegClassInfo;
CodeGenOpt::Level OptLevel;
public:
static char ID;
PostRAScheduler(CodeGenOpt::Level ol) :
- MachineFunctionPass(&ID), OptLevel(ol) {}
+ MachineFunctionPass(ID), OptLevel(ol) {}
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
/// 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
/// KillIndices - The index of the most recent kill (proceding bottom-up),
/// or ~0u if the register is not live.
- unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister];
+ std::vector<unsigned> KillIndices;
public:
- SchedulePostRATDList(MachineFunction &MF,
- const MachineLoopInfo &MLI,
- const MachineDominatorTree &MDT,
- ScheduleHazardRecognizer *HR,
- AntiDepBreaker *ADB,
- AliasAnalysis *aa)
- : ScheduleDAGInstrs(MF, MLI, MDT), Topo(SUnits),
- HazardRec(HR), AntiDepBreak(ADB), AA(aa) {}
-
- ~SchedulePostRATDList() {
- }
+ SchedulePostRATDList(
+ MachineFunction &MF, MachineLoopInfo &MLI, MachineDominatorTree &MDT,
+ AliasAnalysis *AA, const RegisterClassInfo&,
+ TargetSubtargetInfo::AntiDepBreakMode AntiDepMode,
+ SmallVectorImpl<TargetRegisterClass*> &CriticalPathRCs);
+
+ ~SchedulePostRATDList();
/// StartBlock - Initialize register live-range state for scheduling in
/// this block.
/// Schedule - Schedule the instruction range using list scheduling.
///
void Schedule();
-
+
/// Observe - Update liveness information to account for the current
/// instruction, which will not be scheduled.
///
void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
void ListScheduleTopDown();
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.
};
}
-/// 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;
+SchedulePostRATDList::SchedulePostRATDList(
+ MachineFunction &MF, MachineLoopInfo &MLI, MachineDominatorTree &MDT,
+ AliasAnalysis *AA, const RegisterClassInfo &RCI,
+ TargetSubtargetInfo::AntiDepBreakMode AntiDepMode,
+ SmallVectorImpl<TargetRegisterClass*> &CriticalPathRCs)
+ : ScheduleDAGInstrs(MF, MLI, MDT), Topo(SUnits), AA(AA),
+ KillIndices(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;
}
bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
- AA = &getAnalysis<AliasAnalysis>();
+ TII = Fn.getTarget().getInstrInfo();
+ MachineLoopInfo &MLI = getAnalysis<MachineLoopInfo>();
+ MachineDominatorTree &MDT = getAnalysis<MachineDominatorTree>();
+ AliasAnalysis *AA = &getAnalysis<AliasAnalysis>();
+ RegClassInfo.runOnMachineFunction(Fn);
// Check for explicit enable/disable of post-ra scheduling.
- TargetSubtarget::AntiDepBreakMode AntiDepMode = TargetSubtarget::ANTIDEP_NONE;
+ TargetSubtargetInfo::AntiDepBreakMode AntiDepMode = TargetSubtargetInfo::ANTIDEP_NONE;
+ SmallVector<TargetRegisterClass*, 4> CriticalPathRCs;
if (EnablePostRAScheduler.getPosition() > 0) {
if (!EnablePostRAScheduler)
return false;
} else {
// Check that post-RA scheduling is enabled for this target.
- const TargetSubtarget &ST = Fn.getTarget().getSubtarget<TargetSubtarget>();
- if (!ST.enablePostRAScheduler(OptLevel, AntiDepMode))
+ // This may upgrade the AntiDepMode.
+ const TargetSubtargetInfo &ST = Fn.getTarget().getSubtarget<TargetSubtargetInfo>();
+ if (!ST.enablePostRAScheduler(OptLevel, AntiDepMode, CriticalPathRCs))
return false;
}
// Check for antidep breaking override...
if (EnableAntiDepBreaking.getPosition() > 0) {
- AntiDepMode = (EnableAntiDepBreaking == "all") ? TargetSubtarget::ANTIDEP_ALL :
- (EnableAntiDepBreaking == "critical") ? TargetSubtarget::ANTIDEP_CRITICAL :
- TargetSubtarget::ANTIDEP_NONE;
+ AntiDepMode = (EnableAntiDepBreaking == "all")
+ ? TargetSubtargetInfo::ANTIDEP_ALL
+ : ((EnableAntiDepBreaking == "critical")
+ ? TargetSubtargetInfo::ANTIDEP_CRITICAL
+ : TargetSubtargetInfo::ANTIDEP_NONE);
}
- DEBUG(errs() << "PostRAScheduler\n");
+ DEBUG(dbgs() << "PostRAScheduler\n");
- 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();
- AntiDepBreaker *ADB =
- ((AntiDepMode == TargetSubtarget::ANTIDEP_ALL) ?
- (AntiDepBreaker *)new AggressiveAntiDepBreaker(Fn) :
- ((AntiDepMode == TargetSubtarget::ANTIDEP_CRITICAL) ?
- (AntiDepBreaker *)new CriticalAntiDepBreaker(Fn) : NULL));
-
- SchedulePostRATDList Scheduler(Fn, MLI, MDT, HR, ADB, AA);
+ 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()->getNameStr() <<
+ ":BB#" << MBB->getNumber() << " ***\n";
}
#endif
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)) {
+ MachineInstr *MI = llvm::prior(I);
+ if (TII->isSchedulingBoundary(MI, MBB, Fn)) {
Scheduler.Run(MBB, I, Current, CurrentCount);
- Scheduler.EmitSchedule(0);
+ Scheduler.EmitSchedule();
Current = MI;
CurrentCount = Count - 1;
Scheduler.Observe(MI, CurrentCount);
assert((MBB->begin() == Current || CurrentCount != 0) &&
"Instruction count mismatch!");
Scheduler.Run(MBB, MBB->begin(), Current, CurrentCount);
- Scheduler.EmitSchedule(0);
+ Scheduler.EmitSchedule();
// Clean up register live-range state.
Scheduler.FinishBlock();
Scheduler.FixupKills(MBB);
}
- delete HR;
- delete ADB;
-
return true;
}
-
+
/// StartBlock - Initialize register live-range state for scheduling in
/// this block.
///
/// Schedule - Schedule the instruction range using list scheduling.
///
void SchedulePostRATDList::Schedule() {
- DEBUG(errs() << "********** List Scheduling **********\n");
-
// Build the scheduling graph.
BuildSchedGraph(AA);
if (AntiDepBreak != NULL) {
- unsigned Broken =
+ unsigned Broken =
AntiDepBreak->BreakAntiDependencies(SUnits, Begin, InsertPos,
- InsertPosIndex);
- if (Broken > 0) {
+ InsertPosIndex, 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
// that register, and add new anti-dependence and output-dependence
// edges based on the next live range of the register.
SUnits.clear();
+ Sequence.clear();
EntrySU = SUnit();
ExitSU = SUnit();
BuildSchedGraph(AA);
}
}
+ 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();
}
///
void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) {
// Initialize the indices to indicate that no registers are live.
- std::fill(KillIndices, array_endof(KillIndices), ~0u);
+ for (unsigned i = 0; i < TRI->getNumRegs(); ++i)
+ KillIndices[i] = ~0u;
// Determine the live-out physregs for this block.
if (!BB->empty() && BB->back().getDesc().isReturn()) {
MO.setIsKill(true);
return false;
}
-
+
// If MO itself is live, clear the kill flag...
if (KillIndices[MO.getReg()] != ~0u) {
MO.setIsKill(false);
/// 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 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
if (!MO.isDef()) continue;
// Ignore two-addr defs.
if (MI->isRegTiedToUseOperand(i)) continue;
-
+
KillIndices[Reg] = ~0u;
-
+
// Repeat for all subregs.
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
if (kill)
kill = (KillIndices[Reg] == ~0u);
}
-
+
if (MO.isKill() != kill) {
- bool removed = ToggleKillFlag(MI, MO);
- if (removed) {
- DEBUG(errs() << "Fixed <removed> in ");
- } else {
- DEBUG(errs() << "Fixed " << MO << " in ");
- }
+ DEBUG(dbgs() << "Fixing " << MO << " in ");
+ // Warning: ToggleKillFlag may invalidate MO.
+ ToggleKillFlag(MI, MO);
DEBUG(MI->dump());
}
-
+
killedRegs.insert(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) {
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
KillIndices[Reg] = Count;
-
+
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
KillIndices[*Subreg] = Count;
#ifndef NDEBUG
if (SuccSU->NumPredsLeft == 0) {
- errs() << "*** Scheduling failed! ***\n";
+ 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
--SuccSU->NumPredsLeft;
- // 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());
-
+ // 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);
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;
}
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);
CycleHasInsts = true;
-
- // 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;
+ if (HazardRec->atIssueLimit()) {
+ DEBUG(dbgs() << "*** Max instructions per cycle " << CurCycle << '\n');
+ HazardRec->AdvanceCycle();
+ ++CurCycle;
+ CycleHasInsts = false;
}
} else {
if (CycleHasInsts) {
- DEBUG(errs() << "*** Finished cycle " << CurCycle << '\n');
+ 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;
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