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llvm-mirror/lib/CodeGen/PostRASchedulerList.cpp

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//===----- SchedulePostRAList.cpp - list scheduler ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements a top-down list scheduler, using standard algorithms.
// The basic approach uses a priority queue of available nodes to schedule.
// One at a time, nodes are taken from the priority queue (thus in priority
// order), checked for legality to schedule, and emitted if legal.
//
// Nodes may not be legal to schedule either due to structural hazards (e.g.
// pipeline or resource constraints) or because an input to the instruction has
// not completed execution.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "post-RA-sched"
#include "ExactHazardRecognizer.h"
#include "SimpleHazardRecognizer.h"
#include "ScheduleDAGInstrs.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/LatencyPriorityQueue.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtarget.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/Statistic.h"
#include <map>
#include <set>
using namespace llvm;
STATISTIC(NumNoops, "Number of noops inserted");
STATISTIC(NumStalls, "Number of pipeline stalls");
STATISTIC(NumFixedAnti, "Number of fixed anti-dependencies");
// Post-RA scheduling is enabled with
// TargetSubtarget.enablePostRAScheduler(). This flag can be used to
// override the target.
static cl::opt<bool>
EnablePostRAScheduler("post-RA-scheduler",
cl::desc("Enable scheduling after register allocation"),
cl::init(false), cl::Hidden);
static cl::opt<std::string>
EnableAntiDepBreaking("break-anti-dependencies",
cl::desc("Break post-RA scheduling anti-dependencies: "
"\"critical\", \"all\", or \"none\""),
cl::init("critical"), 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>
DebugDiv("postra-sched-debugdiv",
cl::desc("Debug control MBBs that are scheduled"),
cl::init(0), cl::Hidden);
static cl::opt<int>
DebugMod("postra-sched-debugmod",
cl::desc("Debug control MBBs that are scheduled"),
cl::init(0), cl::Hidden);
namespace {
class VISIBILITY_HIDDEN PostRAScheduler : public MachineFunctionPass {
AliasAnalysis *AA;
CodeGenOpt::Level OptLevel;
public:
static char ID;
PostRAScheduler(CodeGenOpt::Level ol) :
MachineFunctionPass(&ID), OptLevel(ol) {}
void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<AliasAnalysis>();
AU.addRequired<MachineDominatorTree>();
AU.addPreserved<MachineDominatorTree>();
AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
const char *getPassName() const {
return "Post RA top-down list latency scheduler";
}
bool runOnMachineFunction(MachineFunction &Fn);
};
char PostRAScheduler::ID = 0;
class VISIBILITY_HIDDEN SchedulePostRATDList : public ScheduleDAGInstrs {
/// RegisterReference - Information about a register reference
/// within a liverange
typedef struct {
/// Operand - The registers operand
MachineOperand *Operand;
/// RC - The register class
const TargetRegisterClass *RC;
} RegisterReference;
/// 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
/// added to the AvailableQueue.
std::vector<SUnit*> PendingQueue;
/// Topo - A topological ordering for SUnits.
ScheduleDAGTopologicalSort Topo;
/// HazardRec - The hazard recognizer to use.
ScheduleHazardRecognizer *HazardRec;
/// AA - AliasAnalysis for making memory reference queries.
AliasAnalysis *AA;
/// AllocatableSet - The set of allocatable registers.
/// We'll be ignoring anti-dependencies on non-allocatable registers,
/// because they may not be safe to break.
const BitVector AllocatableSet;
/// GroupNodes - Implements a disjoint-union data structure to
/// form register groups. A node is represented by an index into
/// the vector. A node can "point to" itself to indicate that it
/// is the parent of a group, or point to another node to indicate
/// that it is a member of the same group as that node.
std::vector<unsigned> GroupNodes;
/// GroupNodeIndices - For each register, the index of the GroupNode
/// currently representing the group that the register belongs to.
/// Register 0 is always represented by the 0 group, a group
/// composed of registers that are not eligible for anti-aliasing.
unsigned GroupNodeIndices[TargetRegisterInfo::FirstVirtualRegister];
/// RegRegs - Map registers to all their references within a live range.
std::multimap<unsigned, RegisterReference> RegRefs;
/// KillIndices - The index of the most recent kill (proceding
/// bottom-up), or ~0u if no kill of the register has been
/// seen. The register is live if this index != ~0u and DefIndices
/// == ~0u.
unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister];
/// DefIndices - The index of the most recent complete def (proceding bottom
/// up), or ~0u if the register is live.
unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister];
public:
SchedulePostRATDList(MachineFunction &MF,
const MachineLoopInfo &MLI,
const MachineDominatorTree &MDT,
ScheduleHazardRecognizer *HR,
AliasAnalysis *aa)
: ScheduleDAGInstrs(MF, MLI, MDT), Topo(SUnits),
HazardRec(HR), AA(aa),
AllocatableSet(TRI->getAllocatableSet(MF)),
GroupNodes(TargetRegisterInfo::FirstVirtualRegister, 0) {}
~SchedulePostRATDList() {
delete HazardRec;
}
/// StartBlock - Initialize register live-range state for scheduling in
/// this block.
///
void StartBlock(MachineBasicBlock *BB);
/// FinishBlock - Clean up register live-range state.
///
void FinishBlock();
/// Observe - Update liveness information to account for the current
/// instruction, which will not be scheduled.
///
void Observe(MachineInstr *MI, unsigned Count);
/// Schedule - Schedule the instruction range using list scheduling.
///
void Schedule();
/// FixupKills - Fix register kill flags that have been made
/// invalid due to scheduling
///
void FixupKills(MachineBasicBlock *MBB);
private:
/// IsLive - Return true if Reg is live
bool IsLive(unsigned Reg);
void PrescanInstruction(MachineInstr *MI, unsigned Count);
void ScanInstruction(MachineInstr *MI, unsigned Count);
bool BreakAntiDependencies(bool CriticalPathOnly);
unsigned FindSuitableFreeRegister(unsigned AntiDepReg);
void ReleaseSucc(SUnit *SU, SDep *SuccEdge);
void ReleaseSuccessors(SUnit *SU);
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.
bool ToggleKillFlag(MachineInstr *MI, MachineOperand &MO);
// GetGroup - Get the group for a register. The returned value is
// the index of the GroupNode representing the group.
unsigned GetGroup(unsigned Reg);
// GetGroupRegs - Return a vector of the registers belonging to a
// group.
void GetGroupRegs(unsigned Group, std::vector<unsigned> &Regs);
// UnionGroups - Union Reg1's and Reg2's groups to form a new
// group. Return the index of the GroupNode representing the
// group.
unsigned UnionGroups(unsigned Reg1, unsigned Reg2);
// LeaveGroup - Remove a register from its current group and place
// it alone in its own group. Return the index of the GroupNode
// representing the registers new group.
unsigned LeaveGroup(unsigned Reg);
};
}
/// 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;
return false;
}
bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) {
AA = &getAnalysis<AliasAnalysis>();
// Check for explicit enable/disable of post-ra scheduling.
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))
return false;
}
DEBUG(errs() << "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();
SchedulePostRATDList Scheduler(Fn, MLI, MDT, HR, AA);
// Loop over all of the basic blocks
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
MBB != MBBe; ++MBB) {
#ifndef NDEBUG
// If DebugDiv > 0 then only schedule MBB with (ID % DebugDiv) == DebugMod
if (DebugDiv > 0) {
static int bbcnt = 0;
if (bbcnt++ % DebugDiv != DebugMod)
continue;
errs() << "*** DEBUG scheduling " << Fn.getFunction()->getNameStr() <<
":MBB ID#" << MBB->getNumber() << " ***\n";
}
#endif
// Initialize register live-range state for scheduling in this block.
Scheduler.StartBlock(MBB);
// Schedule each sequence of instructions not interrupted by a label
// or anything else that effectively needs to shut down scheduling.
MachineBasicBlock::iterator Current = MBB->end();
unsigned Count = MBB->size(), CurrentCount = Count;
for (MachineBasicBlock::iterator I = Current; I != MBB->begin(); ) {
MachineInstr *MI = prior(I);
if (isSchedulingBoundary(MI, Fn)) {
Scheduler.Run(MBB, I, Current, CurrentCount);
Scheduler.EmitSchedule(0);
Current = MI;
CurrentCount = Count - 1;
Scheduler.Observe(MI, CurrentCount);
}
I = MI;
--Count;
}
assert(Count == 0 && "Instruction count mismatch!");
assert((MBB->begin() == Current || CurrentCount != 0) &&
"Instruction count mismatch!");
Scheduler.Run(MBB, MBB->begin(), Current, CurrentCount);
Scheduler.EmitSchedule(0);
// Clean up register live-range state.
Scheduler.FinishBlock();
// Update register kills
Scheduler.FixupKills(MBB);
}
return true;
}
unsigned SchedulePostRATDList::GetGroup(unsigned Reg)
{
unsigned Node = GroupNodeIndices[Reg];
while (GroupNodes[Node] != Node)
Node = GroupNodes[Node];
return Node;
}
void SchedulePostRATDList::GetGroupRegs(unsigned Group, std::vector<unsigned> &Regs)
{
for (unsigned Reg = 0; Reg != TargetRegisterInfo::FirstVirtualRegister; ++Reg) {
if (GetGroup(Reg) == Group)
Regs.push_back(Reg);
}
}
unsigned SchedulePostRATDList::UnionGroups(unsigned Reg1, unsigned Reg2)
{
assert(GroupNodes[0] == 0 && "GroupNode 0 not parent!");
assert(GroupNodeIndices[0] == 0 && "Reg 0 not in Group 0!");
// find group for each register
unsigned Group1 = GetGroup(Reg1);
unsigned Group2 = GetGroup(Reg2);
// if either group is 0, then that must become the parent
unsigned Parent = (Group1 == 0) ? Group1 : Group2;
unsigned Other = (Parent == Group1) ? Group2 : Group1;
GroupNodes.at(Other) = Parent;
return Parent;
}
unsigned SchedulePostRATDList::LeaveGroup(unsigned Reg)
{
// Create a new GroupNode for Reg. Reg's existing GroupNode must
// stay as is because there could be other GroupNodes referring to
// it.
unsigned idx = GroupNodes.size();
GroupNodes.push_back(idx);
GroupNodeIndices[Reg] = idx;
return idx;
}
bool SchedulePostRATDList::IsLive(unsigned Reg)
{
// KillIndex must be defined and DefIndex not defined for a register
// to be live.
return((KillIndices[Reg] != ~0u) && (DefIndices[Reg] == ~0u));
}
/// StartBlock - Initialize register live-range state for scheduling in
/// this block.
///
void SchedulePostRATDList::StartBlock(MachineBasicBlock *BB) {
// Call the superclass.
ScheduleDAGInstrs::StartBlock(BB);
// Reset the hazard recognizer.
HazardRec->Reset();
// Initialize all registers to be in their own group. Initially we
// assign the register to the same-indexed GroupNode.
for (unsigned i = 0; i < TargetRegisterInfo::FirstVirtualRegister; ++i)
GroupNodeIndices[i] = i;
// Initialize the indices to indicate that no registers are live.
std::fill(KillIndices, array_endof(KillIndices), ~0u);
std::fill(DefIndices, array_endof(DefIndices), BB->size());
bool IsReturnBlock = (!BB->empty() && BB->back().getDesc().isReturn());
// Determine the live-out physregs for this block.
if (IsReturnBlock) {
// In a return block, examine the function live-out regs.
for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(),
E = MRI.liveout_end(); I != E; ++I) {
unsigned Reg = *I;
UnionGroups(Reg, 0);
KillIndices[Reg] = BB->size();
DefIndices[Reg] = ~0u;
// Repeat, for all aliases.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
UnionGroups(AliasReg, 0);
KillIndices[AliasReg] = BB->size();
DefIndices[AliasReg] = ~0u;
}
}
} else {
// In a non-return block, examine the live-in regs of all successors.
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
SE = BB->succ_end(); SI != SE; ++SI)
for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(),
E = (*SI)->livein_end(); I != E; ++I) {
unsigned Reg = *I;
UnionGroups(Reg, 0);
KillIndices[Reg] = BB->size();
DefIndices[Reg] = ~0u;
// Repeat, for all aliases.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
UnionGroups(AliasReg, 0);
KillIndices[AliasReg] = BB->size();
DefIndices[AliasReg] = ~0u;
}
}
}
// Mark live-out callee-saved registers. In a return block this is
// all callee-saved registers. In non-return this is any
// callee-saved register that is not saved in the prolog.
const MachineFrameInfo *MFI = MF.getFrameInfo();
BitVector Pristine = MFI->getPristineRegs(BB);
for (const unsigned *I = TRI->getCalleeSavedRegs(); *I; ++I) {
unsigned Reg = *I;
if (!IsReturnBlock && !Pristine.test(Reg)) continue;
UnionGroups(Reg, 0);
KillIndices[Reg] = BB->size();
DefIndices[Reg] = ~0u;
// Repeat, for all aliases.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
UnionGroups(AliasReg, 0);
KillIndices[AliasReg] = BB->size();
DefIndices[AliasReg] = ~0u;
}
}
}
/// Schedule - Schedule the instruction range using list scheduling.
///
void SchedulePostRATDList::Schedule() {
DEBUG(errs() << "********** List Scheduling **********\n");
// Build the scheduling graph.
BuildSchedGraph(AA);
if (EnableAntiDepBreaking != "none") {
if (BreakAntiDependencies((EnableAntiDepBreaking == "all") ? false : true)) {
// We made changes. Update the dependency graph.
// Theoretically we could update the graph in place:
// When a live range is changed to use a different register, remove
// the def's anti-dependence *and* output-dependence edges due to
// that register, and add new anti-dependence and output-dependence
// edges based on the next live range of the register.
SUnits.clear();
EntrySU = SUnit();
ExitSU = SUnit();
BuildSchedGraph(AA);
}
}
DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
SUnits[su].dumpAll(this));
AvailableQueue.initNodes(SUnits);
ListScheduleTopDown();
AvailableQueue.releaseState();
}
/// Observe - Update liveness information to account for the current
/// instruction, which will not be scheduled.
///
void SchedulePostRATDList::Observe(MachineInstr *MI, unsigned Count) {
assert(Count < InsertPosIndex && "Instruction index out of expected range!");
DEBUG(errs() << "Observe: ");
DEBUG(MI->dump());
for (unsigned Reg = 0; Reg != TargetRegisterInfo::FirstVirtualRegister; ++Reg) {
// If Reg is current live, then mark that it can't be renamed as
// we don't know the extent of its live-range anymore (now that it
// has been scheduled). If it is not live but was defined in the
// previous schedule region, then set its def index to the most
// conservative location (i.e. the beginning of the previous
// schedule region).
if (IsLive(Reg)) {
DEBUG(if (GetGroup(Reg) != 0)
errs() << " " << TRI->getName(Reg) << "=g" <<
GetGroup(Reg) << "->g0(region live-out)");
UnionGroups(Reg, 0);
} else if ((DefIndices[Reg] < InsertPosIndex) && (DefIndices[Reg] >= Count)) {
DefIndices[Reg] = Count;
}
}
PrescanInstruction(MI, Count);
ScanInstruction(MI, Count);
}
/// FinishBlock - Clean up register live-range state.
///
void SchedulePostRATDList::FinishBlock() {
RegRefs.clear();
// Call the superclass.
ScheduleDAGInstrs::FinishBlock();
}
/// CriticalPathStep - Return the next SUnit after SU on the bottom-up
/// critical path.
static SDep *CriticalPathStep(SUnit *SU) {
SDep *Next = 0;
unsigned NextDepth = 0;
// Find the predecessor edge with the greatest depth.
for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end();
P != PE; ++P) {
SUnit *PredSU = P->getSUnit();
unsigned PredLatency = P->getLatency();
unsigned PredTotalLatency = PredSU->getDepth() + PredLatency;
// In the case of a latency tie, prefer an anti-dependency edge over
// other types of edges.
if (NextDepth < PredTotalLatency ||
(NextDepth == PredTotalLatency && P->getKind() == SDep::Anti)) {
NextDepth = PredTotalLatency;
Next = &*P;
}
}
return Next;
}
/// AntiDepPathStep - Return SUnit that SU has an anti-dependence on.
static SDep *AntiDepPathStep(SUnit *SU) {
for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end();
P != PE; ++P) {
if (P->getKind() == SDep::Anti) {
return &*P;
}
}
return 0;
}
void SchedulePostRATDList::PrescanInstruction(MachineInstr *MI, unsigned Count) {
// Scan the register defs for this instruction and update
// live-ranges, groups and RegRefs.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isDef()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
// Ignore two-addr defs for liveness...
if (MI->isRegTiedToUseOperand(i)) continue;
// Update Def for Reg and subregs.
DefIndices[Reg] = Count;
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
unsigned SubregReg = *Subreg;
DefIndices[SubregReg] = Count;
}
}
DEBUG(errs() << "\tDef Groups:");
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isDef()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
DEBUG(errs() << " " << TRI->getName(Reg) << "=g" << GetGroup(Reg));
// If MI's defs have special allocation requirement, don't allow
// any def registers to be changed. Also assume all registers
// defined in a call must not be changed (ABI).
if (MI->getDesc().isCall() || MI->getDesc().hasExtraDefRegAllocReq()) {
DEBUG(if (GetGroup(Reg) != 0) errs() << "->g0(alloc-req)");
UnionGroups(Reg, 0);
}
// Any subregisters that are live at this point are defined here,
// so group those subregisters with Reg.
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
unsigned SubregReg = *Subreg;
if (IsLive(SubregReg)) {
UnionGroups(Reg, SubregReg);
DEBUG(errs() << "->g" << GetGroup(Reg) << "(via " <<
TRI->getName(SubregReg) << ")");
}
}
// Note register reference...
const TargetRegisterClass *RC = NULL;
if (i < MI->getDesc().getNumOperands())
RC = MI->getDesc().OpInfo[i].getRegClass(TRI);
RegisterReference RR = { &MO, RC };
RegRefs.insert(std::make_pair(Reg, RR));
}
DEBUG(errs() << '\n');
}
void SchedulePostRATDList::ScanInstruction(MachineInstr *MI,
unsigned Count) {
DEBUG(errs() << "\tUse Groups:");
// Scan the register uses for this instruction and update
// live-ranges, groups and RegRefs.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isUse()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
DEBUG(errs() << " " << TRI->getName(Reg) << "=g" << GetGroup(Reg));
// It wasn't previously live but now it is, this is a kill. Forget
// the previous live-range information and start a new live-range
// for the register.
if (!IsLive(Reg)) {
KillIndices[Reg] = Count;
DefIndices[Reg] = ~0u;
RegRefs.erase(Reg);
LeaveGroup(Reg);
DEBUG(errs() << "->g" << GetGroup(Reg) << "(last-use)");
}
// Repeat, for subregisters.
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
unsigned SubregReg = *Subreg;
if (!IsLive(SubregReg)) {
KillIndices[SubregReg] = Count;
DefIndices[SubregReg] = ~0u;
RegRefs.erase(SubregReg);
LeaveGroup(SubregReg);
DEBUG(errs() << "->g" << GetGroup(SubregReg) << "(last-use)");
}
}
// If MI's uses have special allocation requirement, don't allow
// any use registers to be changed. Also assume all registers
// used in a call must not be changed (ABI).
if (MI->getDesc().isCall() || MI->getDesc().hasExtraSrcRegAllocReq()) {
DEBUG(if (GetGroup(Reg) != 0) errs() << "->g0(alloc-req)");
UnionGroups(Reg, 0);
}
// Note register reference...
const TargetRegisterClass *RC = NULL;
if (i < MI->getDesc().getNumOperands())
RC = MI->getDesc().OpInfo[i].getRegClass(TRI);
RegisterReference RR = { &MO, RC };
RegRefs.insert(std::make_pair(Reg, RR));
}
DEBUG(errs() << '\n');
// Form a group of all defs and uses of a KILL instruction to ensure
// that all registers are renamed as a group.
if (MI->getOpcode() == TargetInstrInfo::KILL) {
unsigned FirstReg = 0;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
if (FirstReg != 0)
UnionGroups(FirstReg, Reg);
FirstReg = Reg;
}
DEBUG(if (FirstReg != 0) errs() << "\tKill Group: g" <<
GetGroup(FirstReg) << '\n');
}
}
unsigned SchedulePostRATDList::FindSuitableFreeRegister(unsigned AntiDepReg) {
// Collect all registers in the same group as AntiDepReg. These all
// need to be renamed together if we are to break the
// anti-dependence.
std::vector<unsigned> Regs;
GetGroupRegs(GetGroup(AntiDepReg), Regs);
DEBUG(errs() << "\tRename Register Group:");
DEBUG(for (unsigned i = 0, e = Regs.size(); i != e; ++i)
DEBUG(errs() << " " << TRI->getName(Regs[i])));
DEBUG(errs() << "\n");
// If there is a single register that needs to be renamed then we
// can do it ourselves.
if (Regs.size() == 1) {
assert(Regs[0] == AntiDepReg && "Register group does not contain register!");
// Check all references that need rewriting. Gather up all the
// register classes for the register references.
const TargetRegisterClass *FirstRC = NULL;
std::set<const TargetRegisterClass *> RCs;
std::pair<std::multimap<unsigned, RegisterReference>::iterator,
std::multimap<unsigned, RegisterReference>::iterator>
Range = RegRefs.equal_range(AntiDepReg);
for (std::multimap<unsigned, RegisterReference>::iterator
Q = Range.first, QE = Range.second; Q != QE; ++Q) {
const TargetRegisterClass *RC = Q->second.RC;
if (RC == NULL) continue;
if (FirstRC == NULL)
FirstRC = RC;
else if (FirstRC != RC)
RCs.insert(RC);
}
if (FirstRC == NULL)
return 0;
DEBUG(errs() << "\tChecking Regclasses: " << FirstRC->getName());
DEBUG(for (std::set<const TargetRegisterClass *>::iterator S =
RCs.begin(), E = RCs.end(); S != E; ++S)
errs() << " " << (*S)->getName());
DEBUG(errs() << '\n');
// Using the allocation order for one of the register classes,
// find the first register that belongs to all the register
// classes that is available over the liverange of the register.
DEBUG(errs() << "\tFind Register:");
for (TargetRegisterClass::iterator R = FirstRC->allocation_order_begin(MF),
RE = FirstRC->allocation_order_end(MF); R != RE; ++R) {
unsigned NewReg = *R;
// Don't replace a register with itself.
if (NewReg == AntiDepReg) continue;
DEBUG(errs() << " " << TRI->getName(NewReg));
// Make sure NewReg is in all required register classes.
for (std::set<const TargetRegisterClass *>::iterator S =
RCs.begin(), E = RCs.end(); S != E; ++S) {
const TargetRegisterClass *RC = *S;
if (!RC->contains(NewReg)) {
DEBUG(errs() << "(not in " << RC->getName() << ")");
NewReg = 0;
break;
}
}
// If NewReg is dead and NewReg's most recent def is not before
// AntiDepReg's kill, it's safe to replace AntiDepReg with
// NewReg. We must also check all subregisters of NewReg.
if (IsLive(NewReg) || (KillIndices[AntiDepReg] > DefIndices[NewReg])) {
DEBUG(errs() << "(live)");
continue;
}
{
bool found = false;
for (const unsigned *Subreg = TRI->getSubRegisters(NewReg);
*Subreg; ++Subreg) {
unsigned SubregReg = *Subreg;
if (IsLive(SubregReg) || (KillIndices[AntiDepReg] > DefIndices[SubregReg])) {
DEBUG(errs() << "(subreg " << TRI->getName(SubregReg) << " live)");
found = true;
}
}
if (found)
continue;
}
if (NewReg != 0) {
DEBUG(errs() << '\n');
return NewReg;
}
}
DEBUG(errs() << '\n');
}
// No registers are free and available!
return 0;
}
/// BreakAntiDependencies - Identifiy anti-dependencies along the critical path
/// of the ScheduleDAG and break them by renaming registers.
///
bool SchedulePostRATDList::BreakAntiDependencies(bool CriticalPathOnly) {
// The code below assumes that there is at least one instruction,
// so just duck out immediately if the block is empty.
if (SUnits.empty()) return false;
// If breaking anti-dependencies only along the critical path, track
// progress along the critical path through the SUnit graph as we
// walk the instructions.
SUnit *CriticalPathSU = 0;
MachineInstr *CriticalPathMI = 0;
// If breaking all anti-dependencies need a map from MI to SUnit.
std::map<MachineInstr *, SUnit *> MISUnitMap;
// Find the node at the bottom of the critical path.
if (CriticalPathOnly) {
SUnit *Max = 0;
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
SUnit *SU = &SUnits[i];
if (!Max || SU->getDepth() + SU->Latency > Max->getDepth() + Max->Latency)
Max = SU;
}
DEBUG(errs() << "Critical path has total latency "
<< (Max->getDepth() + Max->Latency) << "\n");
CriticalPathSU = Max;
CriticalPathMI = CriticalPathSU->getInstr();
} else {
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
SUnit *SU = &SUnits[i];
MISUnitMap.insert(std::pair<MachineInstr *, SUnit *>(SU->getInstr(), SU));
}
DEBUG(errs() << "Breaking all anti-dependencies\n");
}
#ifndef NDEBUG
{
DEBUG(errs() << "Available regs:");
for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) {
if (!IsLive(Reg))
DEBUG(errs() << " " << TRI->getName(Reg));
}
DEBUG(errs() << '\n');
}
std::string dbgStr;
#endif
// Attempt to break anti-dependence edges. Walk the instructions
// from the bottom up, tracking information about liveness as we go
// to help determine which registers are available.
bool Changed = false;
unsigned Count = InsertPosIndex - 1;
for (MachineBasicBlock::iterator I = InsertPos, E = Begin;
I != E; --Count) {
MachineInstr *MI = --I;
DEBUG(errs() << "Anti: ");
DEBUG(MI->dump());
// Process the defs in MI...
PrescanInstruction(MI, Count);
// Check if this instruction has an anti-dependence that we may be
// able to break. If it is, set AntiDepReg to the non-zero
// register associated with the anti-dependence.
//
unsigned AntiDepReg = 0;
// Limiting our attention to the critical path is a heuristic to avoid
// breaking anti-dependence edges that aren't going to significantly
// impact the overall schedule. There are a limited number of registers
// and we want to save them for the important edges.
//
// We can also break all anti-dependencies because they can
// occur along the non-critical path but are still detrimental for
// scheduling.
//
// TODO: Instructions with multiple defs could have multiple
// anti-dependencies. The current code here only knows how to break one
// edge per instruction. Note that we'd have to be able to break all of
// the anti-dependencies in an instruction in order to be effective.
if (!CriticalPathOnly || (MI == CriticalPathMI)) {
DEBUG(dbgStr.clear());
SUnit *PathSU;
SDep *Edge;
if (CriticalPathOnly) {
PathSU = CriticalPathSU;
Edge = CriticalPathStep(PathSU);
} else {
PathSU = MISUnitMap[MI];
Edge = (PathSU) ? AntiDepPathStep(PathSU) : 0;
}
if (Edge) {
SUnit *NextSU = Edge->getSUnit();
// Only consider anti-dependence edges, and ignore KILL
// instructions (they form a group in ScanInstruction but
// don't cause any anti-dependence breaking themselves)
if ((Edge->getKind() == SDep::Anti) &&
(MI->getOpcode() != TargetInstrInfo::KILL)) {
AntiDepReg = Edge->getReg();
DEBUG(dbgStr += "\tAntidep reg: ");
DEBUG(dbgStr += TRI->getName(AntiDepReg));
assert(AntiDepReg != 0 && "Anti-dependence on reg0?");
if (!AllocatableSet.test(AntiDepReg)) {
// Don't break anti-dependencies on non-allocatable registers.
DEBUG(dbgStr += " (non-allocatable)");
AntiDepReg = 0;
} else {
int OpIdx = MI->findRegisterDefOperandIdx(AntiDepReg);
assert(OpIdx != -1 && "Can't find index for defined register operand");
if (MI->isRegTiedToUseOperand(OpIdx)) {
// If the anti-dep register is tied to a use, then don't try to
// change it. It will be changed along with the use if required
// to break an earlier antidep.
DEBUG(dbgStr += " (tied-to-use)");
AntiDepReg = 0;
} else {
// If the SUnit has other dependencies on the SUnit that
// it anti-depends on, don't bother breaking the
// anti-dependency since those edges would prevent such
// units from being scheduled past each other
// regardless.
//
// Also, if there are dependencies on other SUnits with
// the same register as the anti-dependency, don't
// attempt to break it.
for (SUnit::pred_iterator P = PathSU->Preds.begin(),
PE = PathSU->Preds.end(); P != PE; ++P) {
if (P->getSUnit() == NextSU ?
(P->getKind() != SDep::Anti || P->getReg() != AntiDepReg) :
(P->getKind() == SDep::Data && P->getReg() == AntiDepReg)) {
DEBUG(dbgStr += " (real dependency)");
AntiDepReg = 0;
break;
}
}
}
}
}
if (CriticalPathOnly) {
CriticalPathSU = NextSU;
CriticalPathMI = CriticalPathSU->getInstr();
}
} else {
// We've reached the end of the critical path.
CriticalPathSU = 0;
CriticalPathMI = 0;
}
}
// Determine AntiDepReg's register group.
const unsigned GroupIndex = AntiDepReg != 0 ? GetGroup(AntiDepReg) : 0;
if (GroupIndex == 0) {
DEBUG(if (AntiDepReg != 0) dbgStr += " (zero group)");
AntiDepReg = 0;
}
DEBUG(if (!dbgStr.empty()) errs() << dbgStr << '\n');
// Look for a suitable register to use to break the anti-dependence.
if (AntiDepReg != 0) {
if (unsigned NewReg = FindSuitableFreeRegister(AntiDepReg)) {
DEBUG(errs() << "\tBreaking anti-dependence edge on "
<< TRI->getName(AntiDepReg)
<< " with " << RegRefs.count(AntiDepReg) << " references"
<< " using " << TRI->getName(NewReg) << "!\n");
// Update the references to the old register to refer to the new
// register.
std::pair<std::multimap<unsigned, RegisterReference>::iterator,
std::multimap<unsigned, RegisterReference>::iterator>
Range = RegRefs.equal_range(AntiDepReg);
for (std::multimap<unsigned, RegisterReference>::iterator
Q = Range.first, QE = Range.second; Q != QE; ++Q)
Q->second.Operand->setReg(NewReg);
// We just went back in time and modified history; the
// liveness information for the anti-dependence reg is now
// inconsistent. Set the state as if it were dead.
// FIXME forall in group
UnionGroups(NewReg, 0);
RegRefs.erase(NewReg);
DefIndices[NewReg] = DefIndices[AntiDepReg];
KillIndices[NewReg] = KillIndices[AntiDepReg];
// FIXME forall in group
UnionGroups(AntiDepReg, 0);
RegRefs.erase(AntiDepReg);
DefIndices[AntiDepReg] = KillIndices[AntiDepReg];
KillIndices[AntiDepReg] = ~0u;
assert(((KillIndices[AntiDepReg] == ~0u) !=
(DefIndices[AntiDepReg] == ~0u)) &&
"Kill and Def maps aren't consistent for AntiDepReg!");
Changed = true;
++NumFixedAnti;
}
}
ScanInstruction(MI, Count);
}
return Changed;
}
/// StartBlockForKills - Initialize register live-range state for updating kills
///
void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) {
// Initialize the indices to indicate that no registers are live.
std::fill(KillIndices, array_endof(KillIndices), ~0u);
// Determine the live-out physregs for this block.
if (!BB->empty() && BB->back().getDesc().isReturn()) {
// In a return block, examine the function live-out regs.
for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(),
E = MRI.liveout_end(); I != E; ++I) {
unsigned Reg = *I;
KillIndices[Reg] = BB->size();
// Repeat, for all subregs.
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
KillIndices[*Subreg] = BB->size();
}
}
}
else {
// In a non-return block, examine the live-in regs of all successors.
for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(),
SE = BB->succ_end(); SI != SE; ++SI) {
for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(),
E = (*SI)->livein_end(); I != E; ++I) {
unsigned Reg = *I;
KillIndices[Reg] = BB->size();
// Repeat, for all subregs.
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
KillIndices[*Subreg] = BB->size();
}
}
}
}
}
bool SchedulePostRATDList::ToggleKillFlag(MachineInstr *MI,
MachineOperand &MO) {
// Setting kill flag...
if (!MO.isKill()) {
MO.setIsKill(true);
return false;
}
// If MO itself is live, clear the kill flag...
if (KillIndices[MO.getReg()] != ~0u) {
MO.setIsKill(false);
return false;
}
// If any subreg of MO is live, then create an imp-def for that
// subreg and keep MO marked as killed.
MO.setIsKill(false);
bool AllDead = true;
const unsigned SuperReg = MO.getReg();
for (const unsigned *Subreg = TRI->getSubRegisters(SuperReg);
*Subreg; ++Subreg) {
if (KillIndices[*Subreg] != ~0u) {
MI->addOperand(MachineOperand::CreateReg(*Subreg,
true /*IsDef*/,
true /*IsImp*/,
false /*IsKill*/,
false /*IsDead*/));
AllDead = false;
}
}
if (AllDead)
MO.setIsKill(true);
return false;
}
/// FixupKills - Fix the register kill flags, they may have been made
/// incorrect by instruction reordering.
///
void SchedulePostRATDList::FixupKills(MachineBasicBlock *MBB) {
DEBUG(errs() << "Fixup kills for BB ID#" << MBB->getNumber() << '\n');
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;
// Update liveness. Registers that are defed but not used in this
// instruction are now dead. Mark register and all subregs as they
// are completely defined.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
if (!MO.isDef()) continue;
// Ignore two-addr defs.
if (MI->isRegTiedToUseOperand(i)) continue;
KillIndices[Reg] = ~0u;
// Repeat for all subregs.
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
KillIndices[*Subreg] = ~0u;
}
}
// Examine all used registers and set/clear kill flag. When a
// register is used multiple times we only set the kill flag on
// the first use.
killedRegs.clear();
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isUse()) continue;
unsigned Reg = MO.getReg();
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
bool kill = false;
if (killedRegs.find(Reg) == killedRegs.end()) {
kill = true;
// A register is not killed if any subregs are live...
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
if (KillIndices[*Subreg] != ~0u) {
kill = false;
break;
}
}
// If subreg is not live, then register is killed if it became
// live in this instruction
if (kill)
kill = (KillIndices[Reg] == ~0u);
}
if (MO.isKill() != kill) {
bool removed = ToggleKillFlag(MI, MO);
if (removed) {
DEBUG(errs() << "Fixed <removed> in ");
} else {
DEBUG(errs() << "Fixed " << MO << " in ");
}
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) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg() || !MO.isUse() || MO.isUndef()) continue;
unsigned Reg = MO.getReg();
if ((Reg == 0) || ReservedRegs.test(Reg)) continue;
KillIndices[Reg] = Count;
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
KillIndices[*Subreg] = Count;
}
}
}
}
//===----------------------------------------------------------------------===//
// Top-Down Scheduling
//===----------------------------------------------------------------------===//
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
/// the PendingQueue if the count reaches zero. Also update its cycle bound.
void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge) {
SUnit *SuccSU = SuccEdge->getSUnit();
#ifndef NDEBUG
if (SuccSU->NumPredsLeft == 0) {
errs() << "*** Scheduling failed! ***\n";
SuccSU->dump(this);
errs() << " 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());
// 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)
PendingQueue.push_back(SuccSU);
}
/// 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)
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(SU->dump(this));
Sequence.push_back(SU);
assert(CurCycle >= SU->getDepth() && "Node scheduled above its depth!");
SU->setDepthToAtLeast(CurCycle);
ReleaseSuccessors(SU);
SU->isScheduled = true;
AvailableQueue.ScheduledNode(SU);
}
/// ListScheduleTopDown - The main loop of list scheduling for top-down
/// schedulers.
void SchedulePostRATDList::ListScheduleTopDown() {
unsigned CurCycle = 0;
// Release any successors of the special Entry node.
ReleaseSuccessors(&EntrySU);
// 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()) {
AvailableQueue.push(&SUnits[i]);
SUnits[i].isAvailable = true;
}
}
// In any cycle where we can't schedule any instructions, we must
// stall or emit a noop, depending on the target.
bool CycleHasInsts = false;
// While Available queue is not empty, grab the node with the highest
// priority. If it is not ready put it back. Schedule the node.
std::vector<SUnit*> NotReady;
Sequence.reserve(SUnits.size());
while (!AvailableQueue.empty() || !PendingQueue.empty()) {
// Check to see if any of the pending instructions are ready to issue. If
// so, add them to the available queue.
unsigned MinDepth = ~0u;
for (unsigned i = 0, e = PendingQueue.size(); i != e; ++i) {
if (PendingQueue[i]->getDepth() <= CurCycle) {
AvailableQueue.push(PendingQueue[i]);
PendingQueue[i]->isAvailable = true;
PendingQueue[i] = PendingQueue.back();
PendingQueue.pop_back();
--i; --e;
} else if (PendingQueue[i]->getDepth() < MinDepth)
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);
});
SUnit *FoundSUnit = 0;
bool HasNoopHazards = false;
while (!AvailableQueue.empty()) {
SUnit *CurSUnit = AvailableQueue.pop();
ScheduleHazardRecognizer::HazardType HT =
HazardRec->getHazardType(CurSUnit);
if (HT == ScheduleHazardRecognizer::NoHazard) {
FoundSUnit = CurSUnit;
break;
}
// Remember if this is a noop hazard.
HasNoopHazards |= HT == ScheduleHazardRecognizer::NoopHazard;
NotReady.push_back(CurSUnit);
}
// Add the nodes that aren't ready back onto the available list.
if (!NotReady.empty()) {
AvailableQueue.push_all(NotReady);
NotReady.clear();
}
// If we found a node to schedule, do it now.
if (FoundSUnit) {
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;
}
} else {
if (CycleHasInsts) {
DEBUG(errs() << "*** 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');
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');
HazardRec->EmitNoop();
Sequence.push_back(0); // NULL here means noop
++NumNoops;
}
++CurCycle;
CycleHasInsts = false;
}
}
#ifndef NDEBUG
VerifySchedule(/*isBottomUp=*/false);
#endif
}
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
FunctionPass *llvm::createPostRAScheduler(CodeGenOpt::Level OptLevel) {
return new PostRAScheduler(OptLevel);
}
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