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llvm-6502/lib/CodeGen/MachineScheduler.cpp
Andrew Trick 5dca613978 Dump LIS before regalloc. MI sched changes them. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187107 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-25 07:26:26 +00:00

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//===- MachineScheduler.cpp - Machine Instruction Scheduler ---------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// MachineScheduler schedules machine instructions after phi elimination. It
// preserves LiveIntervals so it can be invoked before register allocation.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "misched"
#include "llvm/CodeGen/MachineScheduler.h"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/PriorityQueue.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegisterClassInfo.h"
#include "llvm/CodeGen/ScheduleDFS.h"
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
#include <queue>
using namespace llvm;
namespace llvm {
cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden,
cl::desc("Force top-down list scheduling"));
cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden,
cl::desc("Force bottom-up list scheduling"));
}
#ifndef NDEBUG
static cl::opt<bool> ViewMISchedDAGs("view-misched-dags", cl::Hidden,
cl::desc("Pop up a window to show MISched dags after they are processed"));
static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden,
cl::desc("Stop scheduling after N instructions"), cl::init(~0U));
#else
static bool ViewMISchedDAGs = false;
#endif // NDEBUG
static cl::opt<bool> EnableLoadCluster("misched-cluster", cl::Hidden,
cl::desc("Enable load clustering."), cl::init(true));
// Experimental heuristics
static cl::opt<bool> EnableMacroFusion("misched-fusion", cl::Hidden,
cl::desc("Enable scheduling for macro fusion."), cl::init(true));
static cl::opt<bool> VerifyScheduling("verify-misched", cl::Hidden,
cl::desc("Verify machine instrs before and after machine scheduling"));
// DAG subtrees must have at least this many nodes.
static const unsigned MinSubtreeSize = 8;
//===----------------------------------------------------------------------===//
// Machine Instruction Scheduling Pass and Registry
//===----------------------------------------------------------------------===//
MachineSchedContext::MachineSchedContext():
MF(0), MLI(0), MDT(0), PassConfig(0), AA(0), LIS(0) {
RegClassInfo = new RegisterClassInfo();
}
MachineSchedContext::~MachineSchedContext() {
delete RegClassInfo;
}
namespace {
/// MachineScheduler runs after coalescing and before register allocation.
class MachineScheduler : public MachineSchedContext,
public MachineFunctionPass {
public:
MachineScheduler();
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
virtual void releaseMemory() {}
virtual bool runOnMachineFunction(MachineFunction&);
virtual void print(raw_ostream &O, const Module* = 0) const;
static char ID; // Class identification, replacement for typeinfo
};
} // namespace
char MachineScheduler::ID = 0;
char &llvm::MachineSchedulerID = MachineScheduler::ID;
INITIALIZE_PASS_BEGIN(MachineScheduler, "misched",
"Machine Instruction Scheduler", false, false)
INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
INITIALIZE_PASS_END(MachineScheduler, "misched",
"Machine Instruction Scheduler", false, false)
MachineScheduler::MachineScheduler()
: MachineFunctionPass(ID) {
initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
}
void MachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequiredID(MachineDominatorsID);
AU.addRequired<MachineLoopInfo>();
AU.addRequired<AliasAnalysis>();
AU.addRequired<TargetPassConfig>();
AU.addRequired<SlotIndexes>();
AU.addPreserved<SlotIndexes>();
AU.addRequired<LiveIntervals>();
AU.addPreserved<LiveIntervals>();
MachineFunctionPass::getAnalysisUsage(AU);
}
MachinePassRegistry MachineSchedRegistry::Registry;
/// A dummy default scheduler factory indicates whether the scheduler
/// is overridden on the command line.
static ScheduleDAGInstrs *useDefaultMachineSched(MachineSchedContext *C) {
return 0;
}
/// MachineSchedOpt allows command line selection of the scheduler.
static cl::opt<MachineSchedRegistry::ScheduleDAGCtor, false,
RegisterPassParser<MachineSchedRegistry> >
MachineSchedOpt("misched",
cl::init(&useDefaultMachineSched), cl::Hidden,
cl::desc("Machine instruction scheduler to use"));
static MachineSchedRegistry
DefaultSchedRegistry("default", "Use the target's default scheduler choice.",
useDefaultMachineSched);
/// Forward declare the standard machine scheduler. This will be used as the
/// default scheduler if the target does not set a default.
static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C);
/// Decrement this iterator until reaching the top or a non-debug instr.
static MachineBasicBlock::iterator
priorNonDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator Beg) {
assert(I != Beg && "reached the top of the region, cannot decrement");
while (--I != Beg) {
if (!I->isDebugValue())
break;
}
return I;
}
/// If this iterator is a debug value, increment until reaching the End or a
/// non-debug instruction.
static MachineBasicBlock::iterator
nextIfDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator End) {
for(; I != End; ++I) {
if (!I->isDebugValue())
break;
}
return I;
}
/// Top-level MachineScheduler pass driver.
///
/// Visit blocks in function order. Divide each block into scheduling regions
/// and visit them bottom-up. Visiting regions bottom-up is not required, but is
/// consistent with the DAG builder, which traverses the interior of the
/// scheduling regions bottom-up.
///
/// This design avoids exposing scheduling boundaries to the DAG builder,
/// simplifying the DAG builder's support for "special" target instructions.
/// At the same time the design allows target schedulers to operate across
/// scheduling boundaries, for example to bundle the boudary instructions
/// without reordering them. This creates complexity, because the target
/// scheduler must update the RegionBegin and RegionEnd positions cached by
/// ScheduleDAGInstrs whenever adding or removing instructions. A much simpler
/// design would be to split blocks at scheduling boundaries, but LLVM has a
/// general bias against block splitting purely for implementation simplicity.
bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) {
DEBUG(dbgs() << "Before MISsched:\n"; mf.print(dbgs()));
// Initialize the context of the pass.
MF = &mf;
MLI = &getAnalysis<MachineLoopInfo>();
MDT = &getAnalysis<MachineDominatorTree>();
PassConfig = &getAnalysis<TargetPassConfig>();
AA = &getAnalysis<AliasAnalysis>();
LIS = &getAnalysis<LiveIntervals>();
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
if (VerifyScheduling) {
DEBUG(LIS->dump());
MF->verify(this, "Before machine scheduling.");
}
RegClassInfo->runOnMachineFunction(*MF);
// Select the scheduler, or set the default.
MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt;
if (Ctor == useDefaultMachineSched) {
// Get the default scheduler set by the target.
Ctor = MachineSchedRegistry::getDefault();
if (!Ctor) {
Ctor = createConvergingSched;
MachineSchedRegistry::setDefault(Ctor);
}
}
// Instantiate the selected scheduler.
OwningPtr<ScheduleDAGInstrs> Scheduler(Ctor(this));
// Visit all machine basic blocks.
//
// TODO: Visit blocks in global postorder or postorder within the bottom-up
// loop tree. Then we can optionally compute global RegPressure.
for (MachineFunction::iterator MBB = MF->begin(), MBBEnd = MF->end();
MBB != MBBEnd; ++MBB) {
Scheduler->startBlock(MBB);
// Break the block into scheduling regions [I, RegionEnd), and schedule each
// region as soon as it is discovered. RegionEnd points the scheduling
// boundary at the bottom of the region. The DAG does not include RegionEnd,
// but the region does (i.e. the next RegionEnd is above the previous
// RegionBegin). If the current block has no terminator then RegionEnd ==
// MBB->end() for the bottom region.
//
// The Scheduler may insert instructions during either schedule() or
// exitRegion(), even for empty regions. So the local iterators 'I' and
// 'RegionEnd' are invalid across these calls.
unsigned RemainingInstrs = MBB->size();
for(MachineBasicBlock::iterator RegionEnd = MBB->end();
RegionEnd != MBB->begin(); RegionEnd = Scheduler->begin()) {
// Avoid decrementing RegionEnd for blocks with no terminator.
if (RegionEnd != MBB->end()
|| TII->isSchedulingBoundary(llvm::prior(RegionEnd), MBB, *MF)) {
--RegionEnd;
// Count the boundary instruction.
--RemainingInstrs;
}
// The next region starts above the previous region. Look backward in the
// instruction stream until we find the nearest boundary.
MachineBasicBlock::iterator I = RegionEnd;
for(;I != MBB->begin(); --I, --RemainingInstrs) {
if (TII->isSchedulingBoundary(llvm::prior(I), MBB, *MF))
break;
}
// Notify the scheduler of the region, even if we may skip scheduling
// it. Perhaps it still needs to be bundled.
Scheduler->enterRegion(MBB, I, RegionEnd, RemainingInstrs);
// Skip empty scheduling regions (0 or 1 schedulable instructions).
if (I == RegionEnd || I == llvm::prior(RegionEnd)) {
// Close the current region. Bundle the terminator if needed.
// This invalidates 'RegionEnd' and 'I'.
Scheduler->exitRegion();
continue;
}
DEBUG(dbgs() << "********** MI Scheduling **********\n");
DEBUG(dbgs() << MF->getName()
<< ":BB#" << MBB->getNumber() << " " << MBB->getName()
<< "\n From: " << *I << " To: ";
if (RegionEnd != MBB->end()) dbgs() << *RegionEnd;
else dbgs() << "End";
dbgs() << " Remaining: " << RemainingInstrs << "\n");
// Schedule a region: possibly reorder instructions.
// This invalidates 'RegionEnd' and 'I'.
Scheduler->schedule();
// Close the current region.
Scheduler->exitRegion();
// Scheduling has invalidated the current iterator 'I'. Ask the
// scheduler for the top of it's scheduled region.
RegionEnd = Scheduler->begin();
}
assert(RemainingInstrs == 0 && "Instruction count mismatch!");
Scheduler->finishBlock();
}
Scheduler->finalizeSchedule();
DEBUG(LIS->dump());
if (VerifyScheduling)
MF->verify(this, "After machine scheduling.");
return true;
}
void MachineScheduler::print(raw_ostream &O, const Module* m) const {
// unimplemented
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void ReadyQueue::dump() {
dbgs() << Name << ": ";
for (unsigned i = 0, e = Queue.size(); i < e; ++i)
dbgs() << Queue[i]->NodeNum << " ";
dbgs() << "\n";
}
#endif
//===----------------------------------------------------------------------===//
// ScheduleDAGMI - Base class for MachineInstr scheduling with LiveIntervals
// preservation.
//===----------------------------------------------------------------------===//
ScheduleDAGMI::~ScheduleDAGMI() {
delete DFSResult;
DeleteContainerPointers(Mutations);
delete SchedImpl;
}
bool ScheduleDAGMI::canAddEdge(SUnit *SuccSU, SUnit *PredSU) {
return SuccSU == &ExitSU || !Topo.IsReachable(PredSU, SuccSU);
}
bool ScheduleDAGMI::addEdge(SUnit *SuccSU, const SDep &PredDep) {
if (SuccSU != &ExitSU) {
// Do not use WillCreateCycle, it assumes SD scheduling.
// If Pred is reachable from Succ, then the edge creates a cycle.
if (Topo.IsReachable(PredDep.getSUnit(), SuccSU))
return false;
Topo.AddPred(SuccSU, PredDep.getSUnit());
}
SuccSU->addPred(PredDep, /*Required=*/!PredDep.isArtificial());
// Return true regardless of whether a new edge needed to be inserted.
return true;
}
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. When
/// NumPredsLeft reaches zero, release the successor node.
///
/// FIXME: Adjust SuccSU height based on MinLatency.
void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) {
SUnit *SuccSU = SuccEdge->getSUnit();
if (SuccEdge->isWeak()) {
--SuccSU->WeakPredsLeft;
if (SuccEdge->isCluster())
NextClusterSucc = SuccSU;
return;
}
#ifndef NDEBUG
if (SuccSU->NumPredsLeft == 0) {
dbgs() << "*** Scheduling failed! ***\n";
SuccSU->dump(this);
dbgs() << " has been released too many times!\n";
llvm_unreachable(0);
}
#endif
--SuccSU->NumPredsLeft;
if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU)
SchedImpl->releaseTopNode(SuccSU);
}
/// releaseSuccessors - Call releaseSucc on each of SU's successors.
void ScheduleDAGMI::releaseSuccessors(SUnit *SU) {
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
releaseSucc(SU, &*I);
}
}
/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. When
/// NumSuccsLeft reaches zero, release the predecessor node.
///
/// FIXME: Adjust PredSU height based on MinLatency.
void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) {
SUnit *PredSU = PredEdge->getSUnit();
if (PredEdge->isWeak()) {
--PredSU->WeakSuccsLeft;
if (PredEdge->isCluster())
NextClusterPred = PredSU;
return;
}
#ifndef NDEBUG
if (PredSU->NumSuccsLeft == 0) {
dbgs() << "*** Scheduling failed! ***\n";
PredSU->dump(this);
dbgs() << " has been released too many times!\n";
llvm_unreachable(0);
}
#endif
--PredSU->NumSuccsLeft;
if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU)
SchedImpl->releaseBottomNode(PredSU);
}
/// releasePredecessors - Call releasePred on each of SU's predecessors.
void ScheduleDAGMI::releasePredecessors(SUnit *SU) {
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
releasePred(SU, &*I);
}
}
/// This is normally called from the main scheduler loop but may also be invoked
/// by the scheduling strategy to perform additional code motion.
void ScheduleDAGMI::moveInstruction(MachineInstr *MI,
MachineBasicBlock::iterator InsertPos) {
// Advance RegionBegin if the first instruction moves down.
if (&*RegionBegin == MI)
++RegionBegin;
// Update the instruction stream.
BB->splice(InsertPos, BB, MI);
// Update LiveIntervals
LIS->handleMove(MI, /*UpdateFlags=*/true);
// Recede RegionBegin if an instruction moves above the first.
if (RegionBegin == InsertPos)
RegionBegin = MI;
}
bool ScheduleDAGMI::checkSchedLimit() {
#ifndef NDEBUG
if (NumInstrsScheduled == MISchedCutoff && MISchedCutoff != ~0U) {
CurrentTop = CurrentBottom;
return false;
}
++NumInstrsScheduled;
#endif
return true;
}
/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after
/// crossing a scheduling boundary. [begin, end) includes all instructions in
/// the region, including the boundary itself and single-instruction regions
/// that don't get scheduled.
void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb,
MachineBasicBlock::iterator begin,
MachineBasicBlock::iterator end,
unsigned endcount)
{
ScheduleDAGInstrs::enterRegion(bb, begin, end, endcount);
// For convenience remember the end of the liveness region.
LiveRegionEnd =
(RegionEnd == bb->end()) ? RegionEnd : llvm::next(RegionEnd);
}
// Setup the register pressure trackers for the top scheduled top and bottom
// scheduled regions.
void ScheduleDAGMI::initRegPressure() {
TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin);
BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
// Close the RPTracker to finalize live ins.
RPTracker.closeRegion();
DEBUG(RPTracker.getPressure().dump(TRI));
// Initialize the live ins and live outs.
TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs);
BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs);
// Close one end of the tracker so we can call
// getMaxUpward/DownwardPressureDelta before advancing across any
// instructions. This converts currently live regs into live ins/outs.
TopRPTracker.closeTop();
BotRPTracker.closeBottom();
// Account for liveness generated by the region boundary.
if (LiveRegionEnd != RegionEnd)
BotRPTracker.recede();
assert(BotRPTracker.getPos() == RegionEnd && "Can't find the region bottom");
// Cache the list of excess pressure sets in this region. This will also track
// the max pressure in the scheduled code for these sets.
RegionCriticalPSets.clear();
const std::vector<unsigned> &RegionPressure =
RPTracker.getPressure().MaxSetPressure;
for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) {
unsigned Limit = RegClassInfo->getRegPressureSetLimit(i);
if (RegionPressure[i] > Limit) {
DEBUG(dbgs() << TRI->getRegPressureSetName(i)
<< " Limit " << Limit
<< " Actual " << RegionPressure[i] << "\n");
RegionCriticalPSets.push_back(PressureElement(i, 0));
}
}
DEBUG(dbgs() << "Excess PSets: ";
for (unsigned i = 0, e = RegionCriticalPSets.size(); i != e; ++i)
dbgs() << TRI->getRegPressureSetName(
RegionCriticalPSets[i].PSetID) << " ";
dbgs() << "\n");
}
// FIXME: When the pressure tracker deals in pressure differences then we won't
// iterate over all RegionCriticalPSets[i].
void ScheduleDAGMI::
updateScheduledPressure(const std::vector<unsigned> &NewMaxPressure) {
for (unsigned i = 0, e = RegionCriticalPSets.size(); i < e; ++i) {
unsigned ID = RegionCriticalPSets[i].PSetID;
int &MaxUnits = RegionCriticalPSets[i].UnitIncrease;
if ((int)NewMaxPressure[ID] > MaxUnits)
MaxUnits = NewMaxPressure[ID];
}
DEBUG(
for (unsigned i = 0, e = NewMaxPressure.size(); i < e; ++i) {
unsigned Limit = RegClassInfo->getRegPressureSetLimit(i);
if (NewMaxPressure[i] > Limit ) {
dbgs() << " " << TRI->getRegPressureSetName(i) << ": "
<< NewMaxPressure[i] << " > " << Limit << "\n";
}
});
}
/// schedule - Called back from MachineScheduler::runOnMachineFunction
/// after setting up the current scheduling region. [RegionBegin, RegionEnd)
/// only includes instructions that have DAG nodes, not scheduling boundaries.
///
/// This is a skeletal driver, with all the functionality pushed into helpers,
/// so that it can be easilly extended by experimental schedulers. Generally,
/// implementing MachineSchedStrategy should be sufficient to implement a new
/// scheduling algorithm. However, if a scheduler further subclasses
/// ScheduleDAGMI then it will want to override this virtual method in order to
/// update any specialized state.
void ScheduleDAGMI::schedule() {
buildDAGWithRegPressure();
Topo.InitDAGTopologicalSorting();
postprocessDAG();
SmallVector<SUnit*, 8> TopRoots, BotRoots;
findRootsAndBiasEdges(TopRoots, BotRoots);
// Initialize the strategy before modifying the DAG.
// This may initialize a DFSResult to be used for queue priority.
SchedImpl->initialize(this);
DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
SUnits[su].dumpAll(this));
if (ViewMISchedDAGs) viewGraph();
// Initialize ready queues now that the DAG and priority data are finalized.
initQueues(TopRoots, BotRoots);
bool IsTopNode = false;
while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) {
assert(!SU->isScheduled && "Node already scheduled");
if (!checkSchedLimit())
break;
scheduleMI(SU, IsTopNode);
updateQueues(SU, IsTopNode);
}
assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone.");
placeDebugValues();
DEBUG({
unsigned BBNum = begin()->getParent()->getNumber();
dbgs() << "*** Final schedule for BB#" << BBNum << " ***\n";
dumpSchedule();
dbgs() << '\n';
});
}
/// Build the DAG and setup three register pressure trackers.
void ScheduleDAGMI::buildDAGWithRegPressure() {
// Initialize the register pressure tracker used by buildSchedGraph.
RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd);
// Account for liveness generate by the region boundary.
if (LiveRegionEnd != RegionEnd)
RPTracker.recede();
// Build the DAG, and compute current register pressure.
buildSchedGraph(AA, &RPTracker);
// Initialize top/bottom trackers after computing region pressure.
initRegPressure();
}
/// Apply each ScheduleDAGMutation step in order.
void ScheduleDAGMI::postprocessDAG() {
for (unsigned i = 0, e = Mutations.size(); i < e; ++i) {
Mutations[i]->apply(this);
}
}
void ScheduleDAGMI::computeDFSResult() {
if (!DFSResult)
DFSResult = new SchedDFSResult(/*BottomU*/true, MinSubtreeSize);
DFSResult->clear();
ScheduledTrees.clear();
DFSResult->resize(SUnits.size());
DFSResult->compute(SUnits);
ScheduledTrees.resize(DFSResult->getNumSubtrees());
}
void ScheduleDAGMI::findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots,
SmallVectorImpl<SUnit*> &BotRoots) {
for (std::vector<SUnit>::iterator
I = SUnits.begin(), E = SUnits.end(); I != E; ++I) {
SUnit *SU = &(*I);
assert(!SU->isBoundaryNode() && "Boundary node should not be in SUnits");
// Order predecessors so DFSResult follows the critical path.
SU->biasCriticalPath();
// A SUnit is ready to top schedule if it has no predecessors.
if (!I->NumPredsLeft)
TopRoots.push_back(SU);
// A SUnit is ready to bottom schedule if it has no successors.
if (!I->NumSuccsLeft)
BotRoots.push_back(SU);
}
ExitSU.biasCriticalPath();
}
/// Identify DAG roots and setup scheduler queues.
void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots,
ArrayRef<SUnit*> BotRoots) {
NextClusterSucc = NULL;
NextClusterPred = NULL;
// Release all DAG roots for scheduling, not including EntrySU/ExitSU.
//
// Nodes with unreleased weak edges can still be roots.
// Release top roots in forward order.
for (SmallVectorImpl<SUnit*>::const_iterator
I = TopRoots.begin(), E = TopRoots.end(); I != E; ++I) {
SchedImpl->releaseTopNode(*I);
}
// Release bottom roots in reverse order so the higher priority nodes appear
// first. This is more natural and slightly more efficient.
for (SmallVectorImpl<SUnit*>::const_reverse_iterator
I = BotRoots.rbegin(), E = BotRoots.rend(); I != E; ++I) {
SchedImpl->releaseBottomNode(*I);
}
releaseSuccessors(&EntrySU);
releasePredecessors(&ExitSU);
SchedImpl->registerRoots();
// Advance past initial DebugValues.
assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker");
CurrentTop = nextIfDebug(RegionBegin, RegionEnd);
TopRPTracker.setPos(CurrentTop);
CurrentBottom = RegionEnd;
}
/// Move an instruction and update register pressure.
void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) {
// Move the instruction to its new location in the instruction stream.
MachineInstr *MI = SU->getInstr();
if (IsTopNode) {
assert(SU->isTopReady() && "node still has unscheduled dependencies");
if (&*CurrentTop == MI)
CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
else {
moveInstruction(MI, CurrentTop);
TopRPTracker.setPos(MI);
}
// Update top scheduled pressure.
TopRPTracker.advance();
assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure);
}
else {
assert(SU->isBottomReady() && "node still has unscheduled dependencies");
MachineBasicBlock::iterator priorII =
priorNonDebug(CurrentBottom, CurrentTop);
if (&*priorII == MI)
CurrentBottom = priorII;
else {
if (&*CurrentTop == MI) {
CurrentTop = nextIfDebug(++CurrentTop, priorII);
TopRPTracker.setPos(CurrentTop);
}
moveInstruction(MI, CurrentBottom);
CurrentBottom = MI;
}
// Update bottom scheduled pressure.
BotRPTracker.recede();
assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure);
}
}
/// Update scheduler queues after scheduling an instruction.
void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) {
// Release dependent instructions for scheduling.
if (IsTopNode)
releaseSuccessors(SU);
else
releasePredecessors(SU);
SU->isScheduled = true;
if (DFSResult) {
unsigned SubtreeID = DFSResult->getSubtreeID(SU);
if (!ScheduledTrees.test(SubtreeID)) {
ScheduledTrees.set(SubtreeID);
DFSResult->scheduleTree(SubtreeID);
SchedImpl->scheduleTree(SubtreeID);
}
}
// Notify the scheduling strategy after updating the DAG.
SchedImpl->schedNode(SU, IsTopNode);
}
/// Reinsert any remaining debug_values, just like the PostRA scheduler.
void ScheduleDAGMI::placeDebugValues() {
// If first instruction was a DBG_VALUE then put it back.
if (FirstDbgValue) {
BB->splice(RegionBegin, BB, FirstDbgValue);
RegionBegin = FirstDbgValue;
}
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 OrigPrevMI = P.second;
if (&*RegionBegin == DbgValue)
++RegionBegin;
BB->splice(++OrigPrevMI, BB, DbgValue);
if (OrigPrevMI == llvm::prior(RegionEnd))
RegionEnd = DbgValue;
}
DbgValues.clear();
FirstDbgValue = NULL;
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
void ScheduleDAGMI::dumpSchedule() const {
for (MachineBasicBlock::iterator MI = begin(), ME = end(); MI != ME; ++MI) {
if (SUnit *SU = getSUnit(&(*MI)))
SU->dump(this);
else
dbgs() << "Missing SUnit\n";
}
}
#endif
//===----------------------------------------------------------------------===//
// LoadClusterMutation - DAG post-processing to cluster loads.
//===----------------------------------------------------------------------===//
namespace {
/// \brief Post-process the DAG to create cluster edges between neighboring
/// loads.
class LoadClusterMutation : public ScheduleDAGMutation {
struct LoadInfo {
SUnit *SU;
unsigned BaseReg;
unsigned Offset;
LoadInfo(SUnit *su, unsigned reg, unsigned ofs)
: SU(su), BaseReg(reg), Offset(ofs) {}
};
static bool LoadInfoLess(const LoadClusterMutation::LoadInfo &LHS,
const LoadClusterMutation::LoadInfo &RHS);
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
public:
LoadClusterMutation(const TargetInstrInfo *tii,
const TargetRegisterInfo *tri)
: TII(tii), TRI(tri) {}
virtual void apply(ScheduleDAGMI *DAG);
protected:
void clusterNeighboringLoads(ArrayRef<SUnit*> Loads, ScheduleDAGMI *DAG);
};
} // anonymous
bool LoadClusterMutation::LoadInfoLess(
const LoadClusterMutation::LoadInfo &LHS,
const LoadClusterMutation::LoadInfo &RHS) {
if (LHS.BaseReg != RHS.BaseReg)
return LHS.BaseReg < RHS.BaseReg;
return LHS.Offset < RHS.Offset;
}
void LoadClusterMutation::clusterNeighboringLoads(ArrayRef<SUnit*> Loads,
ScheduleDAGMI *DAG) {
SmallVector<LoadClusterMutation::LoadInfo,32> LoadRecords;
for (unsigned Idx = 0, End = Loads.size(); Idx != End; ++Idx) {
SUnit *SU = Loads[Idx];
unsigned BaseReg;
unsigned Offset;
if (TII->getLdStBaseRegImmOfs(SU->getInstr(), BaseReg, Offset, TRI))
LoadRecords.push_back(LoadInfo(SU, BaseReg, Offset));
}
if (LoadRecords.size() < 2)
return;
std::sort(LoadRecords.begin(), LoadRecords.end(), LoadInfoLess);
unsigned ClusterLength = 1;
for (unsigned Idx = 0, End = LoadRecords.size(); Idx < (End - 1); ++Idx) {
if (LoadRecords[Idx].BaseReg != LoadRecords[Idx+1].BaseReg) {
ClusterLength = 1;
continue;
}
SUnit *SUa = LoadRecords[Idx].SU;
SUnit *SUb = LoadRecords[Idx+1].SU;
if (TII->shouldClusterLoads(SUa->getInstr(), SUb->getInstr(), ClusterLength)
&& DAG->addEdge(SUb, SDep(SUa, SDep::Cluster))) {
DEBUG(dbgs() << "Cluster loads SU(" << SUa->NodeNum << ") - SU("
<< SUb->NodeNum << ")\n");
// Copy successor edges from SUa to SUb. Interleaving computation
// dependent on SUa can prevent load combining due to register reuse.
// Predecessor edges do not need to be copied from SUb to SUa since nearby
// loads should have effectively the same inputs.
for (SUnit::const_succ_iterator
SI = SUa->Succs.begin(), SE = SUa->Succs.end(); SI != SE; ++SI) {
if (SI->getSUnit() == SUb)
continue;
DEBUG(dbgs() << " Copy Succ SU(" << SI->getSUnit()->NodeNum << ")\n");
DAG->addEdge(SI->getSUnit(), SDep(SUb, SDep::Artificial));
}
++ClusterLength;
}
else
ClusterLength = 1;
}
}
/// \brief Callback from DAG postProcessing to create cluster edges for loads.
void LoadClusterMutation::apply(ScheduleDAGMI *DAG) {
// Map DAG NodeNum to store chain ID.
DenseMap<unsigned, unsigned> StoreChainIDs;
// Map each store chain to a set of dependent loads.
SmallVector<SmallVector<SUnit*,4>, 32> StoreChainDependents;
for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) {
SUnit *SU = &DAG->SUnits[Idx];
if (!SU->getInstr()->mayLoad())
continue;
unsigned ChainPredID = DAG->SUnits.size();
for (SUnit::const_pred_iterator
PI = SU->Preds.begin(), PE = SU->Preds.end(); PI != PE; ++PI) {
if (PI->isCtrl()) {
ChainPredID = PI->getSUnit()->NodeNum;
break;
}
}
// Check if this chain-like pred has been seen
// before. ChainPredID==MaxNodeID for loads at the top of the schedule.
unsigned NumChains = StoreChainDependents.size();
std::pair<DenseMap<unsigned, unsigned>::iterator, bool> Result =
StoreChainIDs.insert(std::make_pair(ChainPredID, NumChains));
if (Result.second)
StoreChainDependents.resize(NumChains + 1);
StoreChainDependents[Result.first->second].push_back(SU);
}
// Iterate over the store chains.
for (unsigned Idx = 0, End = StoreChainDependents.size(); Idx != End; ++Idx)
clusterNeighboringLoads(StoreChainDependents[Idx], DAG);
}
//===----------------------------------------------------------------------===//
// MacroFusion - DAG post-processing to encourage fusion of macro ops.
//===----------------------------------------------------------------------===//
namespace {
/// \brief Post-process the DAG to create cluster edges between instructions
/// that may be fused by the processor into a single operation.
class MacroFusion : public ScheduleDAGMutation {
const TargetInstrInfo *TII;
public:
MacroFusion(const TargetInstrInfo *tii): TII(tii) {}
virtual void apply(ScheduleDAGMI *DAG);
};
} // anonymous
/// \brief Callback from DAG postProcessing to create cluster edges to encourage
/// fused operations.
void MacroFusion::apply(ScheduleDAGMI *DAG) {
// For now, assume targets can only fuse with the branch.
MachineInstr *Branch = DAG->ExitSU.getInstr();
if (!Branch)
return;
for (unsigned Idx = DAG->SUnits.size(); Idx > 0;) {
SUnit *SU = &DAG->SUnits[--Idx];
if (!TII->shouldScheduleAdjacent(SU->getInstr(), Branch))
continue;
// Create a single weak edge from SU to ExitSU. The only effect is to cause
// bottom-up scheduling to heavily prioritize the clustered SU. There is no
// need to copy predecessor edges from ExitSU to SU, since top-down
// scheduling cannot prioritize ExitSU anyway. To defer top-down scheduling
// of SU, we could create an artificial edge from the deepest root, but it
// hasn't been needed yet.
bool Success = DAG->addEdge(&DAG->ExitSU, SDep(SU, SDep::Cluster));
(void)Success;
assert(Success && "No DAG nodes should be reachable from ExitSU");
DEBUG(dbgs() << "Macro Fuse SU(" << SU->NodeNum << ")\n");
break;
}
}
//===----------------------------------------------------------------------===//
// CopyConstrain - DAG post-processing to encourage copy elimination.
//===----------------------------------------------------------------------===//
namespace {
/// \brief Post-process the DAG to create weak edges from all uses of a copy to
/// the one use that defines the copy's source vreg, most likely an induction
/// variable increment.
class CopyConstrain : public ScheduleDAGMutation {
// Transient state.
SlotIndex RegionBeginIdx;
// RegionEndIdx is the slot index of the last non-debug instruction in the
// scheduling region. So we may have RegionBeginIdx == RegionEndIdx.
SlotIndex RegionEndIdx;
public:
CopyConstrain(const TargetInstrInfo *, const TargetRegisterInfo *) {}
virtual void apply(ScheduleDAGMI *DAG);
protected:
void constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG);
};
} // anonymous
/// constrainLocalCopy handles two possibilities:
/// 1) Local src:
/// I0: = dst
/// I1: src = ...
/// I2: = dst
/// I3: dst = src (copy)
/// (create pred->succ edges I0->I1, I2->I1)
///
/// 2) Local copy:
/// I0: dst = src (copy)
/// I1: = dst
/// I2: src = ...
/// I3: = dst
/// (create pred->succ edges I1->I2, I3->I2)
///
/// Although the MachineScheduler is currently constrained to single blocks,
/// this algorithm should handle extended blocks. An EBB is a set of
/// contiguously numbered blocks such that the previous block in the EBB is
/// always the single predecessor.
void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG) {
LiveIntervals *LIS = DAG->getLIS();
MachineInstr *Copy = CopySU->getInstr();
// Check for pure vreg copies.
unsigned SrcReg = Copy->getOperand(1).getReg();
if (!TargetRegisterInfo::isVirtualRegister(SrcReg))
return;
unsigned DstReg = Copy->getOperand(0).getReg();
if (!TargetRegisterInfo::isVirtualRegister(DstReg))
return;
// Check if either the dest or source is local. If it's live across a back
// edge, it's not local. Note that if both vregs are live across the back
// edge, we cannot successfully contrain the copy without cyclic scheduling.
unsigned LocalReg = DstReg;
unsigned GlobalReg = SrcReg;
LiveInterval *LocalLI = &LIS->getInterval(LocalReg);
if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) {
LocalReg = SrcReg;
GlobalReg = DstReg;
LocalLI = &LIS->getInterval(LocalReg);
if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx))
return;
}
LiveInterval *GlobalLI = &LIS->getInterval(GlobalReg);
// Find the global segment after the start of the local LI.
LiveInterval::iterator GlobalSegment = GlobalLI->find(LocalLI->beginIndex());
// If GlobalLI does not overlap LocalLI->start, then a copy directly feeds a
// local live range. We could create edges from other global uses to the local
// start, but the coalescer should have already eliminated these cases, so
// don't bother dealing with it.
if (GlobalSegment == GlobalLI->end())
return;
// If GlobalSegment is killed at the LocalLI->start, the call to find()
// returned the next global segment. But if GlobalSegment overlaps with
// LocalLI->start, then advance to the next segement. If a hole in GlobalLI
// exists in LocalLI's vicinity, GlobalSegment will be the end of the hole.
if (GlobalSegment->contains(LocalLI->beginIndex()))
++GlobalSegment;
if (GlobalSegment == GlobalLI->end())
return;
// Check if GlobalLI contains a hole in the vicinity of LocalLI.
if (GlobalSegment != GlobalLI->begin()) {
// Two address defs have no hole.
if (SlotIndex::isSameInstr(llvm::prior(GlobalSegment)->end,
GlobalSegment->start)) {
return;
}
// If GlobalLI has a prior segment, it must be live into the EBB. Otherwise
// it would be a disconnected component in the live range.
assert(llvm::prior(GlobalSegment)->start < LocalLI->beginIndex() &&
"Disconnected LRG within the scheduling region.");
}
MachineInstr *GlobalDef = LIS->getInstructionFromIndex(GlobalSegment->start);
if (!GlobalDef)
return;
SUnit *GlobalSU = DAG->getSUnit(GlobalDef);
if (!GlobalSU)
return;
// GlobalDef is the bottom of the GlobalLI hole. Open the hole by
// constraining the uses of the last local def to precede GlobalDef.
SmallVector<SUnit*,8> LocalUses;
const VNInfo *LastLocalVN = LocalLI->getVNInfoBefore(LocalLI->endIndex());
MachineInstr *LastLocalDef = LIS->getInstructionFromIndex(LastLocalVN->def);
SUnit *LastLocalSU = DAG->getSUnit(LastLocalDef);
for (SUnit::const_succ_iterator
I = LastLocalSU->Succs.begin(), E = LastLocalSU->Succs.end();
I != E; ++I) {
if (I->getKind() != SDep::Data || I->getReg() != LocalReg)
continue;
if (I->getSUnit() == GlobalSU)
continue;
if (!DAG->canAddEdge(GlobalSU, I->getSUnit()))
return;
LocalUses.push_back(I->getSUnit());
}
// Open the top of the GlobalLI hole by constraining any earlier global uses
// to precede the start of LocalLI.
SmallVector<SUnit*,8> GlobalUses;
MachineInstr *FirstLocalDef =
LIS->getInstructionFromIndex(LocalLI->beginIndex());
SUnit *FirstLocalSU = DAG->getSUnit(FirstLocalDef);
for (SUnit::const_pred_iterator
I = GlobalSU->Preds.begin(), E = GlobalSU->Preds.end(); I != E; ++I) {
if (I->getKind() != SDep::Anti || I->getReg() != GlobalReg)
continue;
if (I->getSUnit() == FirstLocalSU)
continue;
if (!DAG->canAddEdge(FirstLocalSU, I->getSUnit()))
return;
GlobalUses.push_back(I->getSUnit());
}
DEBUG(dbgs() << "Constraining copy SU(" << CopySU->NodeNum << ")\n");
// Add the weak edges.
for (SmallVectorImpl<SUnit*>::const_iterator
I = LocalUses.begin(), E = LocalUses.end(); I != E; ++I) {
DEBUG(dbgs() << " Local use SU(" << (*I)->NodeNum << ") -> SU("
<< GlobalSU->NodeNum << ")\n");
DAG->addEdge(GlobalSU, SDep(*I, SDep::Weak));
}
for (SmallVectorImpl<SUnit*>::const_iterator
I = GlobalUses.begin(), E = GlobalUses.end(); I != E; ++I) {
DEBUG(dbgs() << " Global use SU(" << (*I)->NodeNum << ") -> SU("
<< FirstLocalSU->NodeNum << ")\n");
DAG->addEdge(FirstLocalSU, SDep(*I, SDep::Weak));
}
}
/// \brief Callback from DAG postProcessing to create weak edges to encourage
/// copy elimination.
void CopyConstrain::apply(ScheduleDAGMI *DAG) {
MachineBasicBlock::iterator FirstPos = nextIfDebug(DAG->begin(), DAG->end());
if (FirstPos == DAG->end())
return;
RegionBeginIdx = DAG->getLIS()->getInstructionIndex(&*FirstPos);
RegionEndIdx = DAG->getLIS()->getInstructionIndex(
&*priorNonDebug(DAG->end(), DAG->begin()));
for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) {
SUnit *SU = &DAG->SUnits[Idx];
if (!SU->getInstr()->isCopy())
continue;
constrainLocalCopy(SU, DAG);
}
}
//===----------------------------------------------------------------------===//
// ConvergingScheduler - Implementation of the generic MachineSchedStrategy.
//===----------------------------------------------------------------------===//
namespace {
/// ConvergingScheduler shrinks the unscheduled zone using heuristics to balance
/// the schedule.
class ConvergingScheduler : public MachineSchedStrategy {
public:
/// Represent the type of SchedCandidate found within a single queue.
/// pickNodeBidirectional depends on these listed by decreasing priority.
enum CandReason {
NoCand, PhysRegCopy, RegExcess, RegCritical, Cluster, Weak, RegMax,
ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce,
TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder};
#ifndef NDEBUG
static const char *getReasonStr(ConvergingScheduler::CandReason Reason);
#endif
/// Policy for scheduling the next instruction in the candidate's zone.
struct CandPolicy {
bool ReduceLatency;
unsigned ReduceResIdx;
unsigned DemandResIdx;
CandPolicy(): ReduceLatency(false), ReduceResIdx(0), DemandResIdx(0) {}
};
/// Status of an instruction's critical resource consumption.
struct SchedResourceDelta {
// Count critical resources in the scheduled region required by SU.
unsigned CritResources;
// Count critical resources from another region consumed by SU.
unsigned DemandedResources;
SchedResourceDelta(): CritResources(0), DemandedResources(0) {}
bool operator==(const SchedResourceDelta &RHS) const {
return CritResources == RHS.CritResources
&& DemandedResources == RHS.DemandedResources;
}
bool operator!=(const SchedResourceDelta &RHS) const {
return !operator==(RHS);
}
};
/// Store the state used by ConvergingScheduler heuristics, required for the
/// lifetime of one invocation of pickNode().
struct SchedCandidate {
CandPolicy Policy;
// The best SUnit candidate.
SUnit *SU;
// The reason for this candidate.
CandReason Reason;
// Set of reasons that apply to multiple candidates.
uint32_t RepeatReasonSet;
// Register pressure values for the best candidate.
RegPressureDelta RPDelta;
// Critical resource consumption of the best candidate.
SchedResourceDelta ResDelta;
SchedCandidate(const CandPolicy &policy)
: Policy(policy), SU(NULL), Reason(NoCand), RepeatReasonSet(0) {}
bool isValid() const { return SU; }
// Copy the status of another candidate without changing policy.
void setBest(SchedCandidate &Best) {
assert(Best.Reason != NoCand && "uninitialized Sched candidate");
SU = Best.SU;
Reason = Best.Reason;
RPDelta = Best.RPDelta;
ResDelta = Best.ResDelta;
}
bool isRepeat(CandReason R) { return RepeatReasonSet & (1 << R); }
void setRepeat(CandReason R) { RepeatReasonSet |= (1 << R); }
void initResourceDelta(const ScheduleDAGMI *DAG,
const TargetSchedModel *SchedModel);
};
/// Summarize the unscheduled region.
struct SchedRemainder {
// Critical path through the DAG in expected latency.
unsigned CriticalPath;
// Scaled count of micro-ops left to schedule.
unsigned RemIssueCount;
// Unscheduled resources
SmallVector<unsigned, 16> RemainingCounts;
void reset() {
CriticalPath = 0;
RemIssueCount = 0;
RemainingCounts.clear();
}
SchedRemainder() { reset(); }
void init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel);
};
/// Each Scheduling boundary is associated with ready queues. It tracks the
/// current cycle in the direction of movement, and maintains the state
/// of "hazards" and other interlocks at the current cycle.
struct SchedBoundary {
ScheduleDAGMI *DAG;
const TargetSchedModel *SchedModel;
SchedRemainder *Rem;
ReadyQueue Available;
ReadyQueue Pending;
bool CheckPending;
// For heuristics, keep a list of the nodes that immediately depend on the
// most recently scheduled node.
SmallPtrSet<const SUnit*, 8> NextSUs;
ScheduleHazardRecognizer *HazardRec;
/// Number of cycles it takes to issue the instructions scheduled in this
/// zone. It is defined as: scheduled-micro-ops / issue-width + stalls.
/// See getStalls().
unsigned CurrCycle;
/// Micro-ops issued in the current cycle
unsigned CurrMOps;
/// MinReadyCycle - Cycle of the soonest available instruction.
unsigned MinReadyCycle;
// The expected latency of the critical path in this scheduled zone.
unsigned ExpectedLatency;
// The latency of dependence chains leading into this zone.
// For each node scheduled top-down: DLat = max DLat, N.Depth.
// For each cycle scheduled: DLat -= 1.
unsigned DependentLatency;
/// Count the scheduled (issued) micro-ops that can be retired by
/// time=CurrCycle assuming the first scheduled instr is retired at time=0.
unsigned RetiredMOps;
// Count scheduled resources that have been executed. Resources are
// considered executed if they become ready in the time that it takes to
// saturate any resource including the one in question. Counts are scaled
// for direct comparison with other resources. Counts can be compared with
// MOps * getMicroOpFactor and Latency * getLatencyFactor.
SmallVector<unsigned, 16> ExecutedResCounts;
/// Cache the max count for a single resource.
unsigned MaxExecutedResCount;
// Cache the critical resources ID in this scheduled zone.
unsigned ZoneCritResIdx;
// Is the scheduled region resource limited vs. latency limited.
bool IsResourceLimited;
#ifndef NDEBUG
// Remember the greatest operand latency as an upper bound on the number of
// times we should retry the pending queue because of a hazard.
unsigned MaxObservedLatency;
#endif
void reset() {
// A new HazardRec is created for each DAG and owned by SchedBoundary.
delete HazardRec;
Available.clear();
Pending.clear();
CheckPending = false;
NextSUs.clear();
HazardRec = 0;
CurrCycle = 0;
CurrMOps = 0;
MinReadyCycle = UINT_MAX;
ExpectedLatency = 0;
DependentLatency = 0;
RetiredMOps = 0;
MaxExecutedResCount = 0;
ZoneCritResIdx = 0;
IsResourceLimited = false;
#ifndef NDEBUG
MaxObservedLatency = 0;
#endif
// Reserve a zero-count for invalid CritResIdx.
ExecutedResCounts.resize(1);
assert(!ExecutedResCounts[0] && "nonzero count for bad resource");
}
/// Pending queues extend the ready queues with the same ID and the
/// PendingFlag set.
SchedBoundary(unsigned ID, const Twine &Name):
DAG(0), SchedModel(0), Rem(0), Available(ID, Name+".A"),
Pending(ID << ConvergingScheduler::LogMaxQID, Name+".P"),
HazardRec(0) {
reset();
}
~SchedBoundary() { delete HazardRec; }
void init(ScheduleDAGMI *dag, const TargetSchedModel *smodel,
SchedRemainder *rem);
bool isTop() const {
return Available.getID() == ConvergingScheduler::TopQID;
}
#ifndef NDEBUG
const char *getResourceName(unsigned PIdx) {
if (!PIdx)
return "MOps";
return SchedModel->getProcResource(PIdx)->Name;
}
#endif
/// Get the number of latency cycles "covered" by the scheduled
/// instructions. This is the larger of the critical path within the zone
/// and the number of cycles required to issue the instructions.
unsigned getScheduledLatency() const {
return std::max(ExpectedLatency, CurrCycle);
}
unsigned getUnscheduledLatency(SUnit *SU) const {
return isTop() ? SU->getHeight() : SU->getDepth();
}
unsigned getResourceCount(unsigned ResIdx) const {
return ExecutedResCounts[ResIdx];
}
/// Get the scaled count of scheduled micro-ops and resources, including
/// executed resources.
unsigned getCriticalCount() const {
if (!ZoneCritResIdx)
return RetiredMOps * SchedModel->getMicroOpFactor();
return getResourceCount(ZoneCritResIdx);
}
/// Get a scaled count for the minimum execution time of the scheduled
/// micro-ops that are ready to execute by getExecutedCount. Notice the
/// feedback loop.
unsigned getExecutedCount() const {
return std::max(CurrCycle * SchedModel->getLatencyFactor(),
MaxExecutedResCount);
}
bool checkHazard(SUnit *SU);
unsigned findMaxLatency(ArrayRef<SUnit*> ReadySUs);
unsigned getOtherResourceCount(unsigned &OtherCritIdx);
void setPolicy(CandPolicy &Policy, SchedBoundary &OtherZone);
void releaseNode(SUnit *SU, unsigned ReadyCycle);
void bumpCycle(unsigned NextCycle);
void incExecutedResources(unsigned PIdx, unsigned Count);
unsigned countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle);
void bumpNode(SUnit *SU);
void releasePending();
void removeReady(SUnit *SU);
SUnit *pickOnlyChoice();
#ifndef NDEBUG
void dumpScheduledState();
#endif
};
private:
ScheduleDAGMI *DAG;
const TargetSchedModel *SchedModel;
const TargetRegisterInfo *TRI;
// State of the top and bottom scheduled instruction boundaries.
SchedRemainder Rem;
SchedBoundary Top;
SchedBoundary Bot;
public:
/// SUnit::NodeQueueId: 0 (none), 1 (top), 2 (bot), 3 (both)
enum {
TopQID = 1,
BotQID = 2,
LogMaxQID = 2
};
ConvergingScheduler():
DAG(0), SchedModel(0), TRI(0), Top(TopQID, "TopQ"), Bot(BotQID, "BotQ") {}
virtual void initialize(ScheduleDAGMI *dag);
virtual SUnit *pickNode(bool &IsTopNode);
virtual void schedNode(SUnit *SU, bool IsTopNode);
virtual void releaseTopNode(SUnit *SU);
virtual void releaseBottomNode(SUnit *SU);
virtual void registerRoots();
protected:
void tryCandidate(SchedCandidate &Cand,
SchedCandidate &TryCand,
SchedBoundary &Zone,
const RegPressureTracker &RPTracker,
RegPressureTracker &TempTracker);
SUnit *pickNodeBidirectional(bool &IsTopNode);
void pickNodeFromQueue(SchedBoundary &Zone,
const RegPressureTracker &RPTracker,
SchedCandidate &Candidate);
void reschedulePhysRegCopies(SUnit *SU, bool isTop);
#ifndef NDEBUG
void traceCandidate(const SchedCandidate &Cand);
#endif
};
} // namespace
void ConvergingScheduler::SchedRemainder::
init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) {
reset();
if (!SchedModel->hasInstrSchedModel())
return;
RemainingCounts.resize(SchedModel->getNumProcResourceKinds());
for (std::vector<SUnit>::iterator
I = DAG->SUnits.begin(), E = DAG->SUnits.end(); I != E; ++I) {
const MCSchedClassDesc *SC = DAG->getSchedClass(&*I);
RemIssueCount += SchedModel->getNumMicroOps(I->getInstr(), SC)
* SchedModel->getMicroOpFactor();
for (TargetSchedModel::ProcResIter
PI = SchedModel->getWriteProcResBegin(SC),
PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
unsigned PIdx = PI->ProcResourceIdx;
unsigned Factor = SchedModel->getResourceFactor(PIdx);
RemainingCounts[PIdx] += (Factor * PI->Cycles);
}
}
}
void ConvergingScheduler::SchedBoundary::
init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) {
reset();
DAG = dag;
SchedModel = smodel;
Rem = rem;
if (SchedModel->hasInstrSchedModel())
ExecutedResCounts.resize(SchedModel->getNumProcResourceKinds());
}
void ConvergingScheduler::initialize(ScheduleDAGMI *dag) {
DAG = dag;
SchedModel = DAG->getSchedModel();
TRI = DAG->TRI;
Rem.init(DAG, SchedModel);
Top.init(DAG, SchedModel, &Rem);
Bot.init(DAG, SchedModel, &Rem);
// Initialize resource counts.
// Initialize the HazardRecognizers. If itineraries don't exist, are empty, or
// are disabled, then these HazardRecs will be disabled.
const InstrItineraryData *Itin = SchedModel->getInstrItineraries();
const TargetMachine &TM = DAG->MF.getTarget();
Top.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG);
Bot.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG);
assert((!ForceTopDown || !ForceBottomUp) &&
"-misched-topdown incompatible with -misched-bottomup");
}
void ConvergingScheduler::releaseTopNode(SUnit *SU) {
if (SU->isScheduled)
return;
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isWeak())
continue;
unsigned PredReadyCycle = I->getSUnit()->TopReadyCycle;
unsigned Latency = I->getLatency();
#ifndef NDEBUG
Top.MaxObservedLatency = std::max(Latency, Top.MaxObservedLatency);
#endif
if (SU->TopReadyCycle < PredReadyCycle + Latency)
SU->TopReadyCycle = PredReadyCycle + Latency;
}
Top.releaseNode(SU, SU->TopReadyCycle);
}
void ConvergingScheduler::releaseBottomNode(SUnit *SU) {
if (SU->isScheduled)
return;
assert(SU->getInstr() && "Scheduled SUnit must have instr");
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->isWeak())
continue;
unsigned SuccReadyCycle = I->getSUnit()->BotReadyCycle;
unsigned Latency = I->getLatency();
#ifndef NDEBUG
Bot.MaxObservedLatency = std::max(Latency, Bot.MaxObservedLatency);
#endif
if (SU->BotReadyCycle < SuccReadyCycle + Latency)
SU->BotReadyCycle = SuccReadyCycle + Latency;
}
Bot.releaseNode(SU, SU->BotReadyCycle);
}
void ConvergingScheduler::registerRoots() {
Rem.CriticalPath = DAG->ExitSU.getDepth();
// Some roots may not feed into ExitSU. Check all of them in case.
for (std::vector<SUnit*>::const_iterator
I = Bot.Available.begin(), E = Bot.Available.end(); I != E; ++I) {
if ((*I)->getDepth() > Rem.CriticalPath)
Rem.CriticalPath = (*I)->getDepth();
}
DEBUG(dbgs() << "Critical Path: " << Rem.CriticalPath << '\n');
}
/// Does this SU have a hazard within the current instruction group.
///
/// The scheduler supports two modes of hazard recognition. The first is the
/// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that
/// supports highly complicated in-order reservation tables
/// (ScoreboardHazardRecognizer) and arbitraty target-specific logic.
///
/// The second is a streamlined mechanism that checks for hazards based on
/// simple counters that the scheduler itself maintains. It explicitly checks
/// for instruction dispatch limitations, including the number of micro-ops that
/// can dispatch per cycle.
///
/// TODO: Also check whether the SU must start a new group.
bool ConvergingScheduler::SchedBoundary::checkHazard(SUnit *SU) {
if (HazardRec->isEnabled())
return HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard;
unsigned uops = SchedModel->getNumMicroOps(SU->getInstr());
if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) {
DEBUG(dbgs() << " SU(" << SU->NodeNum << ") uops="
<< SchedModel->getNumMicroOps(SU->getInstr()) << '\n');
return true;
}
return false;
}
// Find the unscheduled node in ReadySUs with the highest latency.
unsigned ConvergingScheduler::SchedBoundary::
findMaxLatency(ArrayRef<SUnit*> ReadySUs) {
SUnit *LateSU = 0;
unsigned RemLatency = 0;
for (ArrayRef<SUnit*>::iterator I = ReadySUs.begin(), E = ReadySUs.end();
I != E; ++I) {
unsigned L = getUnscheduledLatency(*I);
if (L > RemLatency) {
RemLatency = L;
LateSU = *I;
}
}
if (LateSU) {
DEBUG(dbgs() << Available.getName() << " RemLatency SU("
<< LateSU->NodeNum << ") " << RemLatency << "c\n");
}
return RemLatency;
}
// Count resources in this zone and the remaining unscheduled
// instruction. Return the max count, scaled. Set OtherCritIdx to the critical
// resource index, or zero if the zone is issue limited.
unsigned ConvergingScheduler::SchedBoundary::
getOtherResourceCount(unsigned &OtherCritIdx) {
OtherCritIdx = 0;
if (!SchedModel->hasInstrSchedModel())
return 0;
unsigned OtherCritCount = Rem->RemIssueCount
+ (RetiredMOps * SchedModel->getMicroOpFactor());
DEBUG(dbgs() << " " << Available.getName() << " + Remain MOps: "
<< OtherCritCount / SchedModel->getMicroOpFactor() << '\n');
for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds();
PIdx != PEnd; ++PIdx) {
unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx];
if (OtherCount > OtherCritCount) {
OtherCritCount = OtherCount;
OtherCritIdx = PIdx;
}
}
if (OtherCritIdx) {
DEBUG(dbgs() << " " << Available.getName() << " + Remain CritRes: "
<< OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx)
<< " " << getResourceName(OtherCritIdx) << "\n");
}
return OtherCritCount;
}
/// Set the CandPolicy for this zone given the current resources and latencies
/// inside and outside the zone.
void ConvergingScheduler::SchedBoundary::setPolicy(CandPolicy &Policy,
SchedBoundary &OtherZone) {
// Now that potential stalls have been considered, apply preemptive heuristics
// based on the the total latency and resources inside and outside this
// zone.
// Compute remaining latency. We need this both to determine whether the
// overall schedule has become latency-limited and whether the instructions
// outside this zone are resource or latency limited.
//
// The "dependent" latency is updated incrementally during scheduling as the
// max height/depth of scheduled nodes minus the cycles since it was
// scheduled:
// DLat = max (N.depth - (CurrCycle - N.ReadyCycle) for N in Zone
//
// The "independent" latency is the max ready queue depth:
// ILat = max N.depth for N in Available|Pending
//
// RemainingLatency is the greater of independent and dependent latency.
unsigned RemLatency = DependentLatency;
RemLatency = std::max(RemLatency, findMaxLatency(Available.elements()));
RemLatency = std::max(RemLatency, findMaxLatency(Pending.elements()));
// Compute the critical resource outside the zone.
unsigned OtherCritIdx;
unsigned OtherCount = OtherZone.getOtherResourceCount(OtherCritIdx);
bool OtherResLimited = false;
if (SchedModel->hasInstrSchedModel()) {
unsigned LFactor = SchedModel->getLatencyFactor();
OtherResLimited = (int)(OtherCount - (RemLatency * LFactor)) > (int)LFactor;
}
if (!OtherResLimited && (RemLatency + CurrCycle > Rem->CriticalPath)) {
Policy.ReduceLatency |= true;
DEBUG(dbgs() << " " << Available.getName() << " RemainingLatency "
<< RemLatency << " + " << CurrCycle << "c > CritPath "
<< Rem->CriticalPath << "\n");
}
// If the same resource is limiting inside and outside the zone, do nothing.
if (ZoneCritResIdx == OtherCritIdx)
return;
DEBUG(
if (IsResourceLimited) {
dbgs() << " " << Available.getName() << " ResourceLimited: "
<< getResourceName(ZoneCritResIdx) << "\n";
}
if (OtherResLimited)
dbgs() << " RemainingLimit: " << getResourceName(OtherCritIdx) << "\n";
if (!IsResourceLimited && !OtherResLimited)
dbgs() << " Latency limited both directions.\n");
if (IsResourceLimited && !Policy.ReduceResIdx)
Policy.ReduceResIdx = ZoneCritResIdx;
if (OtherResLimited)
Policy.DemandResIdx = OtherCritIdx;
}
void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU,
unsigned ReadyCycle) {
if (ReadyCycle < MinReadyCycle)
MinReadyCycle = ReadyCycle;
// Check for interlocks first. For the purpose of other heuristics, an
// instruction that cannot issue appears as if it's not in the ReadyQueue.
bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0;
if ((!IsBuffered && ReadyCycle > CurrCycle) || checkHazard(SU))
Pending.push(SU);
else
Available.push(SU);
// Record this node as an immediate dependent of the scheduled node.
NextSUs.insert(SU);
}
/// Move the boundary of scheduled code by one cycle.
void ConvergingScheduler::SchedBoundary::bumpCycle(unsigned NextCycle) {
if (SchedModel->getMicroOpBufferSize() == 0) {
assert(MinReadyCycle < UINT_MAX && "MinReadyCycle uninitialized");
if (MinReadyCycle > NextCycle)
NextCycle = MinReadyCycle;
}
// Update the current micro-ops, which will issue in the next cycle.
unsigned DecMOps = SchedModel->getIssueWidth() * (NextCycle - CurrCycle);
CurrMOps = (CurrMOps <= DecMOps) ? 0 : CurrMOps - DecMOps;
// Decrement DependentLatency based on the next cycle.
if ((NextCycle - CurrCycle) > DependentLatency)
DependentLatency = 0;
else
DependentLatency -= (NextCycle - CurrCycle);
if (!HazardRec->isEnabled()) {
// Bypass HazardRec virtual calls.
CurrCycle = NextCycle;
}
else {
// Bypass getHazardType calls in case of long latency.
for (; CurrCycle != NextCycle; ++CurrCycle) {
if (isTop())
HazardRec->AdvanceCycle();
else
HazardRec->RecedeCycle();
}
}
CheckPending = true;
unsigned LFactor = SchedModel->getLatencyFactor();
IsResourceLimited =
(int)(getCriticalCount() - (getScheduledLatency() * LFactor))
> (int)LFactor;
DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName() << '\n');
}
void ConvergingScheduler::SchedBoundary::incExecutedResources(unsigned PIdx,
unsigned Count) {
ExecutedResCounts[PIdx] += Count;
if (ExecutedResCounts[PIdx] > MaxExecutedResCount)
MaxExecutedResCount = ExecutedResCounts[PIdx];
}
/// Add the given processor resource to this scheduled zone.
///
/// \param Cycles indicates the number of consecutive (non-pipelined) cycles
/// during which this resource is consumed.
///
/// \return the next cycle at which the instruction may execute without
/// oversubscribing resources.
unsigned ConvergingScheduler::SchedBoundary::
countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle) {
unsigned Factor = SchedModel->getResourceFactor(PIdx);
unsigned Count = Factor * Cycles;
DEBUG(dbgs() << " " << getResourceName(PIdx)
<< " +" << Cycles << "x" << Factor << "u\n");
// Update Executed resources counts.
incExecutedResources(PIdx, Count);
assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted");
Rem->RemainingCounts[PIdx] -= Count;
// Check if this resource exceeds the current critical resource. If so, it
// becomes the critical resource.
if (ZoneCritResIdx != PIdx && (getResourceCount(PIdx) > getCriticalCount())) {
ZoneCritResIdx = PIdx;
DEBUG(dbgs() << " *** Critical resource "
<< getResourceName(PIdx) << ": "
<< getResourceCount(PIdx) / SchedModel->getLatencyFactor() << "c\n");
}
// TODO: We don't yet model reserved resources. It's not hard though.
return CurrCycle;
}
/// Move the boundary of scheduled code by one SUnit.
void ConvergingScheduler::SchedBoundary::bumpNode(SUnit *SU) {
// Update the reservation table.
if (HazardRec->isEnabled()) {
if (!isTop() && SU->isCall) {
// Calls are scheduled with their preceding instructions. For bottom-up
// scheduling, clear the pipeline state before emitting.
HazardRec->Reset();
}
HazardRec->EmitInstruction(SU);
}
const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr());
CurrMOps += IncMOps;
// checkHazard prevents scheduling multiple instructions per cycle that exceed
// issue width. However, we commonly reach the maximum. In this case
// opportunistically bump the cycle to avoid uselessly checking everything in
// the readyQ. Furthermore, a single instruction may produce more than one
// cycle's worth of micro-ops.
//
// TODO: Also check if this SU must end a dispatch group.
unsigned NextCycle = CurrCycle;
if (CurrMOps >= SchedModel->getIssueWidth()) {
++NextCycle;
DEBUG(dbgs() << " *** Max MOps " << CurrMOps
<< " at cycle " << CurrCycle << '\n');
}
unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle);
DEBUG(dbgs() << " Ready @" << ReadyCycle << "c\n");
switch (SchedModel->getMicroOpBufferSize()) {
case 0:
assert(ReadyCycle <= CurrCycle && "Broken PendingQueue");
break;
case 1:
if (ReadyCycle > NextCycle) {
NextCycle = ReadyCycle;
DEBUG(dbgs() << " *** Stall until: " << ReadyCycle << "\n");
}
break;
default:
// We don't currently model the OOO reorder buffer, so consider all
// scheduled MOps to be "retired".
break;
}
RetiredMOps += IncMOps;
// Update resource counts and critical resource.
if (SchedModel->hasInstrSchedModel()) {
unsigned DecRemIssue = IncMOps * SchedModel->getMicroOpFactor();
assert(Rem->RemIssueCount >= DecRemIssue && "MOps double counted");
Rem->RemIssueCount -= DecRemIssue;
if (ZoneCritResIdx) {
// Scale scheduled micro-ops for comparing with the critical resource.
unsigned ScaledMOps =
RetiredMOps * SchedModel->getMicroOpFactor();
// If scaled micro-ops are now more than the previous critical resource by
// a full cycle, then micro-ops issue becomes critical.
if ((int)(ScaledMOps - getResourceCount(ZoneCritResIdx))
>= (int)SchedModel->getLatencyFactor()) {
ZoneCritResIdx = 0;
DEBUG(dbgs() << " *** Critical resource NumMicroOps: "
<< ScaledMOps / SchedModel->getLatencyFactor() << "c\n");
}
}
for (TargetSchedModel::ProcResIter
PI = SchedModel->getWriteProcResBegin(SC),
PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
unsigned RCycle =
countResource(PI->ProcResourceIdx, PI->Cycles, ReadyCycle);
if (RCycle > NextCycle)
NextCycle = RCycle;
}
}
// Update ExpectedLatency and DependentLatency.
unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency;
unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency;
if (SU->getDepth() > TopLatency) {
TopLatency = SU->getDepth();
DEBUG(dbgs() << " " << Available.getName()
<< " TopLatency SU(" << SU->NodeNum << ") " << TopLatency << "c\n");
}
if (SU->getHeight() > BotLatency) {
BotLatency = SU->getHeight();
DEBUG(dbgs() << " " << Available.getName()
<< " BotLatency SU(" << SU->NodeNum << ") " << BotLatency << "c\n");
}
// If we stall for any reason, bump the cycle.
if (NextCycle > CurrCycle) {
bumpCycle(NextCycle);
}
else {
// After updating ZoneCritResIdx and ExpectedLatency, check if we're
// resource limited. If a stall occured, bumpCycle does this.
unsigned LFactor = SchedModel->getLatencyFactor();
IsResourceLimited =
(int)(getCriticalCount() - (getScheduledLatency() * LFactor))
> (int)LFactor;
}
DEBUG(dumpScheduledState());
}
/// Release pending ready nodes in to the available queue. This makes them
/// visible to heuristics.
void ConvergingScheduler::SchedBoundary::releasePending() {
// If the available queue is empty, it is safe to reset MinReadyCycle.
if (Available.empty())
MinReadyCycle = UINT_MAX;
// Check to see if any of the pending instructions are ready to issue. If
// so, add them to the available queue.
bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0;
for (unsigned i = 0, e = Pending.size(); i != e; ++i) {
SUnit *SU = *(Pending.begin()+i);
unsigned ReadyCycle = isTop() ? SU->TopReadyCycle : SU->BotReadyCycle;
if (ReadyCycle < MinReadyCycle)
MinReadyCycle = ReadyCycle;
if (!IsBuffered && ReadyCycle > CurrCycle)
continue;
if (checkHazard(SU))
continue;
Available.push(SU);
Pending.remove(Pending.begin()+i);
--i; --e;
}
DEBUG(if (!Pending.empty()) Pending.dump());
CheckPending = false;
}
/// Remove SU from the ready set for this boundary.
void ConvergingScheduler::SchedBoundary::removeReady(SUnit *SU) {
if (Available.isInQueue(SU))
Available.remove(Available.find(SU));
else {
assert(Pending.isInQueue(SU) && "bad ready count");
Pending.remove(Pending.find(SU));
}
}
/// If this queue only has one ready candidate, return it. As a side effect,
/// defer any nodes that now hit a hazard, and advance the cycle until at least
/// one node is ready. If multiple instructions are ready, return NULL.
SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() {
if (CheckPending)
releasePending();
if (CurrMOps > 0) {
// Defer any ready instrs that now have a hazard.
for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) {
if (checkHazard(*I)) {
Pending.push(*I);
I = Available.remove(I);
continue;
}
++I;
}
}
for (unsigned i = 0; Available.empty(); ++i) {
assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedLatency) &&
"permanent hazard"); (void)i;
bumpCycle(CurrCycle + 1);
releasePending();
}
if (Available.size() == 1)
return *Available.begin();
return NULL;
}
#ifndef NDEBUG
// This is useful information to dump after bumpNode.
// Note that the Queue contents are more useful before pickNodeFromQueue.
void ConvergingScheduler::SchedBoundary::dumpScheduledState() {
unsigned ResFactor;
unsigned ResCount;
if (ZoneCritResIdx) {
ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx);
ResCount = getResourceCount(ZoneCritResIdx);
}
else {
ResFactor = SchedModel->getMicroOpFactor();
ResCount = RetiredMOps * SchedModel->getMicroOpFactor();
}
unsigned LFactor = SchedModel->getLatencyFactor();
dbgs() << Available.getName() << " @" << CurrCycle << "c\n"
<< " Retired: " << RetiredMOps;
dbgs() << "\n Executed: " << getExecutedCount() / LFactor << "c";
dbgs() << "\n Critical: " << ResCount / LFactor << "c, "
<< ResCount / ResFactor << " " << getResourceName(ZoneCritResIdx)
<< "\n ExpectedLatency: " << ExpectedLatency << "c\n"
<< (IsResourceLimited ? " - Resource" : " - Latency")
<< " limited.\n";
}
#endif
void ConvergingScheduler::SchedCandidate::
initResourceDelta(const ScheduleDAGMI *DAG,
const TargetSchedModel *SchedModel) {
if (!Policy.ReduceResIdx && !Policy.DemandResIdx)
return;
const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
for (TargetSchedModel::ProcResIter
PI = SchedModel->getWriteProcResBegin(SC),
PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
if (PI->ProcResourceIdx == Policy.ReduceResIdx)
ResDelta.CritResources += PI->Cycles;
if (PI->ProcResourceIdx == Policy.DemandResIdx)
ResDelta.DemandedResources += PI->Cycles;
}
}
/// Return true if this heuristic determines order.
static bool tryLess(int TryVal, int CandVal,
ConvergingScheduler::SchedCandidate &TryCand,
ConvergingScheduler::SchedCandidate &Cand,
ConvergingScheduler::CandReason Reason) {
if (TryVal < CandVal) {
TryCand.Reason = Reason;
return true;
}
if (TryVal > CandVal) {
if (Cand.Reason > Reason)
Cand.Reason = Reason;
return true;
}
Cand.setRepeat(Reason);
return false;
}
static bool tryGreater(int TryVal, int CandVal,
ConvergingScheduler::SchedCandidate &TryCand,
ConvergingScheduler::SchedCandidate &Cand,
ConvergingScheduler::CandReason Reason) {
if (TryVal > CandVal) {
TryCand.Reason = Reason;
return true;
}
if (TryVal < CandVal) {
if (Cand.Reason > Reason)
Cand.Reason = Reason;
return true;
}
Cand.setRepeat(Reason);
return false;
}
static unsigned getWeakLeft(const SUnit *SU, bool isTop) {
return (isTop) ? SU->WeakPredsLeft : SU->WeakSuccsLeft;
}
/// Minimize physical register live ranges. Regalloc wants them adjacent to
/// their physreg def/use.
///
/// FIXME: This is an unnecessary check on the critical path. Most are root/leaf
/// copies which can be prescheduled. The rest (e.g. x86 MUL) could be bundled
/// with the operation that produces or consumes the physreg. We'll do this when
/// regalloc has support for parallel copies.
static int biasPhysRegCopy(const SUnit *SU, bool isTop) {
const MachineInstr *MI = SU->getInstr();
if (!MI->isCopy())
return 0;
unsigned ScheduledOper = isTop ? 1 : 0;
unsigned UnscheduledOper = isTop ? 0 : 1;
// If we have already scheduled the physreg produce/consumer, immediately
// schedule the copy.
if (TargetRegisterInfo::isPhysicalRegister(
MI->getOperand(ScheduledOper).getReg()))
return 1;
// If the physreg is at the boundary, defer it. Otherwise schedule it
// immediately to free the dependent. We can hoist the copy later.
bool AtBoundary = isTop ? !SU->NumSuccsLeft : !SU->NumPredsLeft;
if (TargetRegisterInfo::isPhysicalRegister(
MI->getOperand(UnscheduledOper).getReg()))
return AtBoundary ? -1 : 1;
return 0;
}
/// Apply a set of heursitics to a new candidate. Heuristics are currently
/// hierarchical. This may be more efficient than a graduated cost model because
/// we don't need to evaluate all aspects of the model for each node in the
/// queue. But it's really done to make the heuristics easier to debug and
/// statistically analyze.
///
/// \param Cand provides the policy and current best candidate.
/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized.
/// \param Zone describes the scheduled zone that we are extending.
/// \param RPTracker describes reg pressure within the scheduled zone.
/// \param TempTracker is a scratch pressure tracker to reuse in queries.
void ConvergingScheduler::tryCandidate(SchedCandidate &Cand,
SchedCandidate &TryCand,
SchedBoundary &Zone,
const RegPressureTracker &RPTracker,
RegPressureTracker &TempTracker) {
// Always initialize TryCand's RPDelta.
TempTracker.getMaxPressureDelta(TryCand.SU->getInstr(), TryCand.RPDelta,
DAG->getRegionCriticalPSets(),
DAG->getRegPressure().MaxSetPressure);
// Initialize the candidate if needed.
if (!Cand.isValid()) {
TryCand.Reason = NodeOrder;
return;
}
if (tryGreater(biasPhysRegCopy(TryCand.SU, Zone.isTop()),
biasPhysRegCopy(Cand.SU, Zone.isTop()),
TryCand, Cand, PhysRegCopy))
return;
// Avoid exceeding the target's limit.
if (tryLess(TryCand.RPDelta.Excess.UnitIncrease,
Cand.RPDelta.Excess.UnitIncrease, TryCand, Cand, RegExcess))
return;
// Avoid increasing the max critical pressure in the scheduled region.
if (tryLess(TryCand.RPDelta.CriticalMax.UnitIncrease,
Cand.RPDelta.CriticalMax.UnitIncrease,
TryCand, Cand, RegCritical))
return;
// Keep clustered nodes together to encourage downstream peephole
// optimizations which may reduce resource requirements.
//
// This is a best effort to set things up for a post-RA pass. Optimizations
// like generating loads of multiple registers should ideally be done within
// the scheduler pass by combining the loads during DAG postprocessing.
const SUnit *NextClusterSU =
Zone.isTop() ? DAG->getNextClusterSucc() : DAG->getNextClusterPred();
if (tryGreater(TryCand.SU == NextClusterSU, Cand.SU == NextClusterSU,
TryCand, Cand, Cluster))
return;
// Weak edges are for clustering and other constraints.
if (tryLess(getWeakLeft(TryCand.SU, Zone.isTop()),
getWeakLeft(Cand.SU, Zone.isTop()),
TryCand, Cand, Weak)) {
return;
}
// Avoid increasing the max pressure of the entire region.
if (tryLess(TryCand.RPDelta.CurrentMax.UnitIncrease,
Cand.RPDelta.CurrentMax.UnitIncrease, TryCand, Cand, RegMax))
return;
// Avoid critical resource consumption and balance the schedule.
TryCand.initResourceDelta(DAG, SchedModel);
if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources,
TryCand, Cand, ResourceReduce))
return;
if (tryGreater(TryCand.ResDelta.DemandedResources,
Cand.ResDelta.DemandedResources,
TryCand, Cand, ResourceDemand))
return;
// Avoid serializing long latency dependence chains.
if (Cand.Policy.ReduceLatency) {
if (Zone.isTop()) {
if (Cand.SU->getDepth() > Zone.getScheduledLatency()) {
if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(),
TryCand, Cand, TopDepthReduce))
return;
}
if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(),
TryCand, Cand, TopPathReduce))
return;
}
else {
if (Cand.SU->getHeight() > Zone.getScheduledLatency()) {
if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(),
TryCand, Cand, BotHeightReduce))
return;
}
if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(),
TryCand, Cand, BotPathReduce))
return;
}
}
// Prefer immediate defs/users of the last scheduled instruction. This is a
// local pressure avoidance strategy that also makes the machine code
// readable.
if (tryGreater(Zone.NextSUs.count(TryCand.SU), Zone.NextSUs.count(Cand.SU),
TryCand, Cand, NextDefUse))
return;
// Fall through to original instruction order.
if ((Zone.isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum)
|| (!Zone.isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) {
TryCand.Reason = NodeOrder;
}
}
#ifndef NDEBUG
const char *ConvergingScheduler::getReasonStr(
ConvergingScheduler::CandReason Reason) {
switch (Reason) {
case NoCand: return "NOCAND ";
case PhysRegCopy: return "PREG-COPY";
case RegExcess: return "REG-EXCESS";
case RegCritical: return "REG-CRIT ";
case Cluster: return "CLUSTER ";
case Weak: return "WEAK ";
case RegMax: return "REG-MAX ";
case ResourceReduce: return "RES-REDUCE";
case ResourceDemand: return "RES-DEMAND";
case TopDepthReduce: return "TOP-DEPTH ";
case TopPathReduce: return "TOP-PATH ";
case BotHeightReduce:return "BOT-HEIGHT";
case BotPathReduce: return "BOT-PATH ";
case NextDefUse: return "DEF-USE ";
case NodeOrder: return "ORDER ";
};
llvm_unreachable("Unknown reason!");
}
void ConvergingScheduler::traceCandidate(const SchedCandidate &Cand) {
PressureElement P;
unsigned ResIdx = 0;
unsigned Latency = 0;
switch (Cand.Reason) {
default:
break;
case RegExcess:
P = Cand.RPDelta.Excess;
break;
case RegCritical:
P = Cand.RPDelta.CriticalMax;
break;
case RegMax:
P = Cand.RPDelta.CurrentMax;
break;
case ResourceReduce:
ResIdx = Cand.Policy.ReduceResIdx;
break;
case ResourceDemand:
ResIdx = Cand.Policy.DemandResIdx;
break;
case TopDepthReduce:
Latency = Cand.SU->getDepth();
break;
case TopPathReduce:
Latency = Cand.SU->getHeight();
break;
case BotHeightReduce:
Latency = Cand.SU->getHeight();
break;
case BotPathReduce:
Latency = Cand.SU->getDepth();
break;
}
dbgs() << " SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason);
if (P.isValid())
dbgs() << " " << TRI->getRegPressureSetName(P.PSetID)
<< ":" << P.UnitIncrease << " ";
else
dbgs() << " ";
if (ResIdx)
dbgs() << " " << SchedModel->getProcResource(ResIdx)->Name << " ";
else
dbgs() << " ";
if (Latency)
dbgs() << " " << Latency << " cycles ";
else
dbgs() << " ";
dbgs() << '\n';
}
#endif
/// Pick the best candidate from the top queue.
///
/// TODO: getMaxPressureDelta results can be mostly cached for each SUnit during
/// DAG building. To adjust for the current scheduling location we need to
/// maintain the number of vreg uses remaining to be top-scheduled.
void ConvergingScheduler::pickNodeFromQueue(SchedBoundary &Zone,
const RegPressureTracker &RPTracker,
SchedCandidate &Cand) {
ReadyQueue &Q = Zone.Available;
DEBUG(Q.dump());
// getMaxPressureDelta temporarily modifies the tracker.
RegPressureTracker &TempTracker = const_cast<RegPressureTracker&>(RPTracker);
for (ReadyQueue::iterator I = Q.begin(), E = Q.end(); I != E; ++I) {
SchedCandidate TryCand(Cand.Policy);
TryCand.SU = *I;
tryCandidate(Cand, TryCand, Zone, RPTracker, TempTracker);
if (TryCand.Reason != NoCand) {
// Initialize resource delta if needed in case future heuristics query it.
if (TryCand.ResDelta == SchedResourceDelta())
TryCand.initResourceDelta(DAG, SchedModel);
Cand.setBest(TryCand);
DEBUG(traceCandidate(Cand));
}
}
}
static void tracePick(const ConvergingScheduler::SchedCandidate &Cand,
bool IsTop) {
DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ")
<< ConvergingScheduler::getReasonStr(Cand.Reason) << '\n');
}
/// Pick the best candidate node from either the top or bottom queue.
SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) {
// Schedule as far as possible in the direction of no choice. This is most
// efficient, but also provides the best heuristics for CriticalPSets.
if (SUnit *SU = Bot.pickOnlyChoice()) {
IsTopNode = false;
DEBUG(dbgs() << "Pick Bot NOCAND\n");
return SU;
}
if (SUnit *SU = Top.pickOnlyChoice()) {
IsTopNode = true;
DEBUG(dbgs() << "Pick Top NOCAND\n");
return SU;
}
CandPolicy NoPolicy;
SchedCandidate BotCand(NoPolicy);
SchedCandidate TopCand(NoPolicy);
Bot.setPolicy(BotCand.Policy, Top);
Top.setPolicy(TopCand.Policy, Bot);
// Prefer bottom scheduling when heuristics are silent.
pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand);
assert(BotCand.Reason != NoCand && "failed to find the first candidate");
// If either Q has a single candidate that provides the least increase in
// Excess pressure, we can immediately schedule from that Q.
//
// RegionCriticalPSets summarizes the pressure within the scheduled region and
// affects picking from either Q. If scheduling in one direction must
// increase pressure for one of the excess PSets, then schedule in that
// direction first to provide more freedom in the other direction.
if ((BotCand.Reason == RegExcess && !BotCand.isRepeat(RegExcess))
|| (BotCand.Reason == RegCritical
&& !BotCand.isRepeat(RegCritical)))
{
IsTopNode = false;
tracePick(BotCand, IsTopNode);
return BotCand.SU;
}
// Check if the top Q has a better candidate.
pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand);
assert(TopCand.Reason != NoCand && "failed to find the first candidate");
// Choose the queue with the most important (lowest enum) reason.
if (TopCand.Reason < BotCand.Reason) {
IsTopNode = true;
tracePick(TopCand, IsTopNode);
return TopCand.SU;
}
// Otherwise prefer the bottom candidate, in node order if all else failed.
IsTopNode = false;
tracePick(BotCand, IsTopNode);
return BotCand.SU;
}
/// Pick the best node to balance the schedule. Implements MachineSchedStrategy.
SUnit *ConvergingScheduler::pickNode(bool &IsTopNode) {
if (DAG->top() == DAG->bottom()) {
assert(Top.Available.empty() && Top.Pending.empty() &&
Bot.Available.empty() && Bot.Pending.empty() && "ReadyQ garbage");
return NULL;
}
SUnit *SU;
do {
if (ForceTopDown) {
SU = Top.pickOnlyChoice();
if (!SU) {
CandPolicy NoPolicy;
SchedCandidate TopCand(NoPolicy);
pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand);
assert(TopCand.Reason != NoCand && "failed to find the first candidate");
SU = TopCand.SU;
}
IsTopNode = true;
}
else if (ForceBottomUp) {
SU = Bot.pickOnlyChoice();
if (!SU) {
CandPolicy NoPolicy;
SchedCandidate BotCand(NoPolicy);
pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand);
assert(BotCand.Reason != NoCand && "failed to find the first candidate");
SU = BotCand.SU;
}
IsTopNode = false;
}
else {
SU = pickNodeBidirectional(IsTopNode);
}
} while (SU->isScheduled);
if (SU->isTopReady())
Top.removeReady(SU);
if (SU->isBottomReady())
Bot.removeReady(SU);
DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") " << *SU->getInstr());
return SU;
}
void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) {
MachineBasicBlock::iterator InsertPos = SU->getInstr();
if (!isTop)
++InsertPos;
SmallVectorImpl<SDep> &Deps = isTop ? SU->Preds : SU->Succs;
// Find already scheduled copies with a single physreg dependence and move
// them just above the scheduled instruction.
for (SmallVectorImpl<SDep>::iterator I = Deps.begin(), E = Deps.end();
I != E; ++I) {
if (I->getKind() != SDep::Data || !TRI->isPhysicalRegister(I->getReg()))
continue;
SUnit *DepSU = I->getSUnit();
if (isTop ? DepSU->Succs.size() > 1 : DepSU->Preds.size() > 1)
continue;
MachineInstr *Copy = DepSU->getInstr();
if (!Copy->isCopy())
continue;
DEBUG(dbgs() << " Rescheduling physreg copy ";
I->getSUnit()->dump(DAG));
DAG->moveInstruction(Copy, InsertPos);
}
}
/// Update the scheduler's state after scheduling a node. This is the same node
/// that was just returned by pickNode(). However, ScheduleDAGMI needs to update
/// it's state based on the current cycle before MachineSchedStrategy does.
///
/// FIXME: Eventually, we may bundle physreg copies rather than rescheduling
/// them here. See comments in biasPhysRegCopy.
void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) {
if (IsTopNode) {
SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.CurrCycle);
Top.bumpNode(SU);
if (SU->hasPhysRegUses)
reschedulePhysRegCopies(SU, true);
}
else {
SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.CurrCycle);
Bot.bumpNode(SU);
if (SU->hasPhysRegDefs)
reschedulePhysRegCopies(SU, false);
}
}
/// Create the standard converging machine scheduler. This will be used as the
/// default scheduler if the target does not set a default.
static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C) {
assert((!ForceTopDown || !ForceBottomUp) &&
"-misched-topdown incompatible with -misched-bottomup");
ScheduleDAGMI *DAG = new ScheduleDAGMI(C, new ConvergingScheduler());
// Register DAG post-processors.
//
// FIXME: extend the mutation API to allow earlier mutations to instantiate
// data and pass it to later mutations. Have a single mutation that gathers
// the interesting nodes in one pass.
DAG->addMutation(new CopyConstrain(DAG->TII, DAG->TRI));
if (EnableLoadCluster)
DAG->addMutation(new LoadClusterMutation(DAG->TII, DAG->TRI));
if (EnableMacroFusion)
DAG->addMutation(new MacroFusion(DAG->TII));
return DAG;
}
static MachineSchedRegistry
ConvergingSchedRegistry("converge", "Standard converging scheduler.",
createConvergingSched);
//===----------------------------------------------------------------------===//
// ILP Scheduler. Currently for experimental analysis of heuristics.
//===----------------------------------------------------------------------===//
namespace {
/// \brief Order nodes by the ILP metric.
struct ILPOrder {
const SchedDFSResult *DFSResult;
const BitVector *ScheduledTrees;
bool MaximizeILP;
ILPOrder(bool MaxILP): DFSResult(0), ScheduledTrees(0), MaximizeILP(MaxILP) {}
/// \brief Apply a less-than relation on node priority.
///
/// (Return true if A comes after B in the Q.)
bool operator()(const SUnit *A, const SUnit *B) const {
unsigned SchedTreeA = DFSResult->getSubtreeID(A);
unsigned SchedTreeB = DFSResult->getSubtreeID(B);
if (SchedTreeA != SchedTreeB) {
// Unscheduled trees have lower priority.
if (ScheduledTrees->test(SchedTreeA) != ScheduledTrees->test(SchedTreeB))
return ScheduledTrees->test(SchedTreeB);
// Trees with shallower connections have have lower priority.
if (DFSResult->getSubtreeLevel(SchedTreeA)
!= DFSResult->getSubtreeLevel(SchedTreeB)) {
return DFSResult->getSubtreeLevel(SchedTreeA)
< DFSResult->getSubtreeLevel(SchedTreeB);
}
}
if (MaximizeILP)
return DFSResult->getILP(A) < DFSResult->getILP(B);
else
return DFSResult->getILP(A) > DFSResult->getILP(B);
}
};
/// \brief Schedule based on the ILP metric.
class ILPScheduler : public MachineSchedStrategy {
/// In case all subtrees are eventually connected to a common root through
/// data dependence (e.g. reduction), place an upper limit on their size.
///
/// FIXME: A subtree limit is generally good, but in the situation commented
/// above, where multiple similar subtrees feed a common root, we should
/// only split at a point where the resulting subtrees will be balanced.
/// (a motivating test case must be found).
static const unsigned SubtreeLimit = 16;
ScheduleDAGMI *DAG;
ILPOrder Cmp;
std::vector<SUnit*> ReadyQ;
public:
ILPScheduler(bool MaximizeILP): DAG(0), Cmp(MaximizeILP) {}
virtual void initialize(ScheduleDAGMI *dag) {
DAG = dag;
DAG->computeDFSResult();
Cmp.DFSResult = DAG->getDFSResult();
Cmp.ScheduledTrees = &DAG->getScheduledTrees();
ReadyQ.clear();
}
virtual void registerRoots() {
// Restore the heap in ReadyQ with the updated DFS results.
std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
}
/// Implement MachineSchedStrategy interface.
/// -----------------------------------------
/// Callback to select the highest priority node from the ready Q.
virtual SUnit *pickNode(bool &IsTopNode) {
if (ReadyQ.empty()) return NULL;
std::pop_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
SUnit *SU = ReadyQ.back();
ReadyQ.pop_back();
IsTopNode = false;
DEBUG(dbgs() << "Pick node " << "SU(" << SU->NodeNum << ") "
<< " ILP: " << DAG->getDFSResult()->getILP(SU)
<< " Tree: " << DAG->getDFSResult()->getSubtreeID(SU) << " @"
<< DAG->getDFSResult()->getSubtreeLevel(
DAG->getDFSResult()->getSubtreeID(SU)) << '\n'
<< "Scheduling " << *SU->getInstr());
return SU;
}
/// \brief Scheduler callback to notify that a new subtree is scheduled.
virtual void scheduleTree(unsigned SubtreeID) {
std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
}
/// Callback after a node is scheduled. Mark a newly scheduled tree, notify
/// DFSResults, and resort the priority Q.
virtual void schedNode(SUnit *SU, bool IsTopNode) {
assert(!IsTopNode && "SchedDFSResult needs bottom-up");
}
virtual void releaseTopNode(SUnit *) { /*only called for top roots*/ }
virtual void releaseBottomNode(SUnit *SU) {
ReadyQ.push_back(SU);
std::push_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
}
};
} // namespace
static ScheduleDAGInstrs *createILPMaxScheduler(MachineSchedContext *C) {
return new ScheduleDAGMI(C, new ILPScheduler(true));
}
static ScheduleDAGInstrs *createILPMinScheduler(MachineSchedContext *C) {
return new ScheduleDAGMI(C, new ILPScheduler(false));
}
static MachineSchedRegistry ILPMaxRegistry(
"ilpmax", "Schedule bottom-up for max ILP", createILPMaxScheduler);
static MachineSchedRegistry ILPMinRegistry(
"ilpmin", "Schedule bottom-up for min ILP", createILPMinScheduler);
//===----------------------------------------------------------------------===//
// Machine Instruction Shuffler for Correctness Testing
//===----------------------------------------------------------------------===//
#ifndef NDEBUG
namespace {
/// Apply a less-than relation on the node order, which corresponds to the
/// instruction order prior to scheduling. IsReverse implements greater-than.
template<bool IsReverse>
struct SUnitOrder {
bool operator()(SUnit *A, SUnit *B) const {
if (IsReverse)
return A->NodeNum > B->NodeNum;
else
return A->NodeNum < B->NodeNum;
}
};
/// Reorder instructions as much as possible.
class InstructionShuffler : public MachineSchedStrategy {
bool IsAlternating;
bool IsTopDown;
// Using a less-than relation (SUnitOrder<false>) for the TopQ priority
// gives nodes with a higher number higher priority causing the latest
// instructions to be scheduled first.
PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<false> >
TopQ;
// When scheduling bottom-up, use greater-than as the queue priority.
PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<true> >
BottomQ;
public:
InstructionShuffler(bool alternate, bool topdown)
: IsAlternating(alternate), IsTopDown(topdown) {}
virtual void initialize(ScheduleDAGMI *) {
TopQ.clear();
BottomQ.clear();
}
/// Implement MachineSchedStrategy interface.
/// -----------------------------------------
virtual SUnit *pickNode(bool &IsTopNode) {
SUnit *SU;
if (IsTopDown) {
do {
if (TopQ.empty()) return NULL;
SU = TopQ.top();
TopQ.pop();
} while (SU->isScheduled);
IsTopNode = true;
}
else {
do {
if (BottomQ.empty()) return NULL;
SU = BottomQ.top();
BottomQ.pop();
} while (SU->isScheduled);
IsTopNode = false;
}
if (IsAlternating)
IsTopDown = !IsTopDown;
return SU;
}
virtual void schedNode(SUnit *SU, bool IsTopNode) {}
virtual void releaseTopNode(SUnit *SU) {
TopQ.push(SU);
}
virtual void releaseBottomNode(SUnit *SU) {
BottomQ.push(SU);
}
};
} // namespace
static ScheduleDAGInstrs *createInstructionShuffler(MachineSchedContext *C) {
bool Alternate = !ForceTopDown && !ForceBottomUp;
bool TopDown = !ForceBottomUp;
assert((TopDown || !ForceTopDown) &&
"-misched-topdown incompatible with -misched-bottomup");
return new ScheduleDAGMI(C, new InstructionShuffler(Alternate, TopDown));
}
static MachineSchedRegistry ShufflerRegistry(
"shuffle", "Shuffle machine instructions alternating directions",
createInstructionShuffler);
#endif // !NDEBUG
//===----------------------------------------------------------------------===//
// GraphWriter support for ScheduleDAGMI.
//===----------------------------------------------------------------------===//
#ifndef NDEBUG
namespace llvm {
template<> struct GraphTraits<
ScheduleDAGMI*> : public GraphTraits<ScheduleDAG*> {};
template<>
struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits {
DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
static std::string getGraphName(const ScheduleDAG *G) {
return G->MF.getName();
}
static bool renderGraphFromBottomUp() {
return true;
}
static bool isNodeHidden(const SUnit *Node) {
return (Node->NumPreds > 10 || Node->NumSuccs > 10);
}
static bool hasNodeAddressLabel(const SUnit *Node,
const ScheduleDAG *Graph) {
return false;
}
/// If you want to override the dot attributes printed for a particular
/// edge, override this method.
static std::string getEdgeAttributes(const SUnit *Node,
SUnitIterator EI,
const ScheduleDAG *Graph) {
if (EI.isArtificialDep())
return "color=cyan,style=dashed";
if (EI.isCtrlDep())
return "color=blue,style=dashed";
return "";
}
static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) {
std::string Str;
raw_string_ostream SS(Str);
SS << "SU(" << SU->NodeNum << ')';
return SS.str();
}
static std::string getNodeDescription(const SUnit *SU, const ScheduleDAG *G) {
return G->getGraphNodeLabel(SU);
}
static std::string getNodeAttributes(const SUnit *N,
const ScheduleDAG *Graph) {
std::string Str("shape=Mrecord");
const SchedDFSResult *DFS =
static_cast<const ScheduleDAGMI*>(Graph)->getDFSResult();
if (DFS) {
Str += ",style=filled,fillcolor=\"#";
Str += DOT::getColorString(DFS->getSubtreeID(N));
Str += '"';
}
return Str;
}
};
} // namespace llvm
#endif // NDEBUG
/// viewGraph - Pop up a ghostview window with the reachable parts of the DAG
/// rendered using 'dot'.
///
void ScheduleDAGMI::viewGraph(const Twine &Name, const Twine &Title) {
#ifndef NDEBUG
ViewGraph(this, Name, false, Title);
#else
errs() << "ScheduleDAGMI::viewGraph is only available in debug builds on "
<< "systems with Graphviz or gv!\n";
#endif // NDEBUG
}
/// Out-of-line implementation with no arguments is handy for gdb.
void ScheduleDAGMI::viewGraph() {
viewGraph(getDAGName(), "Scheduling-Units Graph for " + getDAGName());
}
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