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llvm-mirror/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
Evan Cheng bfd74c6d9c Debug tweak. 
llvm-svn: 30959
2006-10-14 08:34:06 +00:00

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//===----- ScheduleDAGList.cpp - Reg pressure reduction list scheduler ----===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Evan Cheng and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements bottom-up and top-down register pressure reduction list
// schedulers, 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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "sched"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Compiler.h"
#include "llvm/ADT/Statistic.h"
#include <climits>
#include <iostream>
#include <queue>
#include "llvm/Support/CommandLine.h"
using namespace llvm;
static RegisterScheduler
burrListDAGScheduler("list-burr",
" Bottom-up register reduction list scheduling",
createBURRListDAGScheduler);
static RegisterScheduler
tdrListrDAGScheduler("list-tdrr",
" Top-down register reduction list scheduling",
createTDRRListDAGScheduler);
namespace {
//===----------------------------------------------------------------------===//
/// ScheduleDAGRRList - The actual register reduction list scheduler
/// implementation. This supports both top-down and bottom-up scheduling.
///
class VISIBILITY_HIDDEN ScheduleDAGRRList : public ScheduleDAG {
private:
/// isBottomUp - This is true if the scheduling problem is bottom-up, false if
/// it is top-down.
bool isBottomUp;
/// AvailableQueue - The priority queue to use for the available SUnits.
///
SchedulingPriorityQueue *AvailableQueue;
public:
ScheduleDAGRRList(SelectionDAG &dag, MachineBasicBlock *bb,
const TargetMachine &tm, bool isbottomup,
SchedulingPriorityQueue *availqueue)
: ScheduleDAG(dag, bb, tm), isBottomUp(isbottomup),
AvailableQueue(availqueue) {
}
~ScheduleDAGRRList() {
delete AvailableQueue;
}
void Schedule();
private:
void ReleasePred(SUnit *PredSU, bool isChain, unsigned CurCycle);
void ReleaseSucc(SUnit *SuccSU, bool isChain, unsigned CurCycle);
void ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle);
void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle);
void ListScheduleTopDown();
void ListScheduleBottomUp();
void CommuteNodesToReducePressure();
};
} // end anonymous namespace
/// Schedule - Schedule the DAG using list scheduling.
void ScheduleDAGRRList::Schedule() {
DEBUG(std::cerr << "********** List Scheduling **********\n");
// Build scheduling units.
BuildSchedUnits();
DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
SUnits[su].dumpAll(&DAG));
CalculateDepths();
CalculateHeights();
AvailableQueue->initNodes(SUnits);
// Execute the actual scheduling loop Top-Down or Bottom-Up as appropriate.
if (isBottomUp)
ListScheduleBottomUp();
else
ListScheduleTopDown();
AvailableQueue->releaseState();
CommuteNodesToReducePressure();
DEBUG(std::cerr << "*** Final schedule ***\n");
DEBUG(dumpSchedule());
DEBUG(std::cerr << "\n");
// Emit in scheduled order
EmitSchedule();
}
/// CommuteNodesToReducePressure - Is a node is two-address and commutable, and
/// it is not the last use of its first operand, add it to the CommuteSet if
/// possible. It will be commuted when it is translated to a MI.
void ScheduleDAGRRList::CommuteNodesToReducePressure() {
std::set<SUnit *> OperandSeen;
for (unsigned i = Sequence.size()-1; i != 0; --i) { // Ignore first node.
SUnit *SU = Sequence[i];
if (!SU) continue;
if (SU->isTwoAddress && SU->isCommutable) {
SDNode *OpN = SU->Node->getOperand(0).Val;
SUnit *OpSU = SUnitMap[OpN];
if (OpSU && OperandSeen.count(OpSU) == 1) {
// Ok, so SU is not the last use of OpSU, but SU is two-address so
// it will clobber OpSU. Try to commute it if possible.
bool DoCommute = true;
for (unsigned j = 1, e = SU->Node->getNumOperands(); j != e; ++j) {
OpN = SU->Node->getOperand(j).Val;
OpSU = SUnitMap[OpN];
if (OpSU && OperandSeen.count(OpSU) == 1) {
DoCommute = false;
break;
}
}
if (DoCommute)
CommuteSet.insert(SU->Node);
}
}
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (!I->second)
OperandSeen.insert(I->first);
}
}
}
//===----------------------------------------------------------------------===//
// Bottom-Up Scheduling
//===----------------------------------------------------------------------===//
static const TargetRegisterClass *getRegClass(SUnit *SU,
const TargetInstrInfo *TII,
const MRegisterInfo *MRI,
SSARegMap *RegMap) {
if (SU->Node->isTargetOpcode()) {
unsigned Opc = SU->Node->getTargetOpcode();
const TargetInstrDescriptor &II = TII->get(Opc);
return MRI->getRegClass(II.OpInfo->RegClass);
} else {
assert(SU->Node->getOpcode() == ISD::CopyFromReg);
unsigned SrcReg = cast<RegisterSDNode>(SU->Node->getOperand(1))->getReg();
if (MRegisterInfo::isVirtualRegister(SrcReg))
return RegMap->getRegClass(SrcReg);
else {
for (MRegisterInfo::regclass_iterator I = MRI->regclass_begin(),
E = MRI->regclass_end(); I != E; ++I)
if ((*I)->hasType(SU->Node->getValueType(0)) &&
(*I)->contains(SrcReg))
return *I;
assert(false && "Couldn't find register class for reg copy!");
}
return NULL;
}
}
static unsigned getNumResults(SUnit *SU) {
unsigned NumResults = 0;
for (unsigned i = 0, e = SU->Node->getNumValues(); i != e; ++i) {
MVT::ValueType VT = SU->Node->getValueType(i);
if (VT != MVT::Other && VT != MVT::Flag)
NumResults++;
}
return NumResults;
}
/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
/// the Available queue is the count reaches zero. Also update its cycle bound.
void ScheduleDAGRRList::ReleasePred(SUnit *PredSU, bool isChain,
unsigned CurCycle) {
// FIXME: the distance between two nodes is not always == the predecessor's
// latency. For example, the reader can very well read the register written
// by the predecessor later than the issue cycle. It also depends on the
// interrupt model (drain vs. freeze).
PredSU->CycleBound = std::max(PredSU->CycleBound, CurCycle + PredSU->Latency);
if (!isChain)
PredSU->NumSuccsLeft--;
else
PredSU->NumChainSuccsLeft--;
#ifndef NDEBUG
if (PredSU->NumSuccsLeft < 0 || PredSU->NumChainSuccsLeft < 0) {
std::cerr << "*** List scheduling failed! ***\n";
PredSU->dump(&DAG);
std::cerr << " has been released too many times!\n";
assert(0);
}
#endif
if ((PredSU->NumSuccsLeft + PredSU->NumChainSuccsLeft) == 0) {
// EntryToken has to go last! Special case it here.
if (PredSU->Node->getOpcode() != ISD::EntryToken) {
PredSU->isAvailable = true;
AvailableQueue->push(PredSU);
}
}
}
/// ScheduleNodeBottomUp - Add the node to the schedule. Decrement the pending
/// count of its predecessors. If a predecessor pending count is zero, add it to
/// the Available queue.
void ScheduleDAGRRList::ScheduleNodeBottomUp(SUnit *SU, unsigned CurCycle) {
DEBUG(std::cerr << "*** Scheduling [" << CurCycle << "]: ");
DEBUG(SU->dump(&DAG));
SU->Cycle = CurCycle;
AvailableQueue->ScheduledNode(SU);
Sequence.push_back(SU);
// Bottom up: release predecessors
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I)
ReleasePred(I->first, I->second, CurCycle);
SU->isScheduled = true;
}
/// isReady - True if node's lower cycle bound is less or equal to the current
/// scheduling cycle. Always true if all nodes have uniform latency 1.
static inline bool isReady(SUnit *SU, unsigned CurCycle) {
return SU->CycleBound <= CurCycle;
}
/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
/// schedulers.
void ScheduleDAGRRList::ListScheduleBottomUp() {
unsigned CurCycle = 0;
// Add root to Available queue.
AvailableQueue->push(SUnitMap[DAG.getRoot().Val]);
// 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;
SUnit *CurNode = NULL;
while (!AvailableQueue->empty()) {
SUnit *CurNode = AvailableQueue->pop();
while (CurNode && !isReady(CurNode, CurCycle)) {
NotReady.push_back(CurNode);
CurNode = AvailableQueue->pop();
}
// Add the nodes that aren't ready back onto the available list.
AvailableQueue->push_all(NotReady);
NotReady.clear();
if (CurNode != NULL)
ScheduleNodeBottomUp(CurNode, CurCycle);
CurCycle++;
}
// Add entry node last
if (DAG.getEntryNode().Val != DAG.getRoot().Val) {
SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
Sequence.push_back(Entry);
}
// Reverse the order if it is bottom up.
std::reverse(Sequence.begin(), Sequence.end());
#ifndef NDEBUG
// Verify that all SUnits were scheduled.
bool AnyNotSched = false;
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
if (SUnits[i].NumSuccsLeft != 0 || SUnits[i].NumChainSuccsLeft != 0) {
if (!AnyNotSched)
std::cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
std::cerr << "has not been scheduled!\n";
AnyNotSched = true;
}
}
assert(!AnyNotSched);
#endif
}
//===----------------------------------------------------------------------===//
// Top-Down Scheduling
//===----------------------------------------------------------------------===//
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
/// the PendingQueue if the count reaches zero.
void ScheduleDAGRRList::ReleaseSucc(SUnit *SuccSU, bool isChain,
unsigned CurCycle) {
// FIXME: the distance between two nodes is not always == the predecessor's
// latency. For example, the reader can very well read the register written
// by the predecessor later than the issue cycle. It also depends on the
// interrupt model (drain vs. freeze).
SuccSU->CycleBound = std::max(SuccSU->CycleBound, CurCycle + SuccSU->Latency);
if (!isChain)
SuccSU->NumPredsLeft--;
else
SuccSU->NumChainPredsLeft--;
#ifndef NDEBUG
if (SuccSU->NumPredsLeft < 0 || SuccSU->NumChainPredsLeft < 0) {
std::cerr << "*** List scheduling failed! ***\n";
SuccSU->dump(&DAG);
std::cerr << " has been released too many times!\n";
assert(0);
}
#endif
if ((SuccSU->NumPredsLeft + SuccSU->NumChainPredsLeft) == 0) {
SuccSU->isAvailable = true;
AvailableQueue->push(SuccSU);
}
}
/// 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 ScheduleDAGRRList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) {
DEBUG(std::cerr << "*** Scheduling [" << CurCycle << "]: ");
DEBUG(SU->dump(&DAG));
SU->Cycle = CurCycle;
AvailableQueue->ScheduledNode(SU);
Sequence.push_back(SU);
// Top down: release successors
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I)
ReleaseSucc(I->first, I->second, CurCycle);
SU->isScheduled = true;
}
void ScheduleDAGRRList::ListScheduleTopDown() {
unsigned CurCycle = 0;
SUnit *Entry = SUnitMap[DAG.getEntryNode().Val];
// 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.size() == 0 && &SUnits[i] != Entry) {
AvailableQueue->push(&SUnits[i]);
SUnits[i].isAvailable = true;
}
}
// Emit the entry node first.
ScheduleNodeTopDown(Entry, CurCycle);
CurCycle++;
// 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;
SUnit *CurNode = NULL;
while (!AvailableQueue->empty()) {
SUnit *CurNode = AvailableQueue->pop();
while (CurNode && !isReady(CurNode, CurCycle)) {
NotReady.push_back(CurNode);
CurNode = AvailableQueue->pop();
}
// Add the nodes that aren't ready back onto the available list.
AvailableQueue->push_all(NotReady);
NotReady.clear();
if (CurNode != NULL)
ScheduleNodeTopDown(CurNode, CurCycle);
CurCycle++;
}
#ifndef NDEBUG
// Verify that all SUnits were scheduled.
bool AnyNotSched = false;
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
if (!SUnits[i].isScheduled) {
if (!AnyNotSched)
std::cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
std::cerr << "has not been scheduled!\n";
AnyNotSched = true;
}
}
assert(!AnyNotSched);
#endif
}
//===----------------------------------------------------------------------===//
// RegReductionPriorityQueue Implementation
//===----------------------------------------------------------------------===//
//
// This is a SchedulingPriorityQueue that schedules using Sethi Ullman numbers
// to reduce register pressure.
//
namespace {
template<class SF>
class RegReductionPriorityQueue;
/// Sorting functions for the Available queue.
struct bu_ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
RegReductionPriorityQueue<bu_ls_rr_sort> *SPQ;
bu_ls_rr_sort(RegReductionPriorityQueue<bu_ls_rr_sort> *spq) : SPQ(spq) {}
bu_ls_rr_sort(const bu_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
bool operator()(const SUnit* left, const SUnit* right) const;
};
struct td_ls_rr_sort : public std::binary_function<SUnit*, SUnit*, bool> {
RegReductionPriorityQueue<td_ls_rr_sort> *SPQ;
td_ls_rr_sort(RegReductionPriorityQueue<td_ls_rr_sort> *spq) : SPQ(spq) {}
td_ls_rr_sort(const td_ls_rr_sort &RHS) : SPQ(RHS.SPQ) {}
bool operator()(const SUnit* left, const SUnit* right) const;
};
} // end anonymous namespace
namespace {
template<class SF>
class VISIBILITY_HIDDEN RegReductionPriorityQueue
: public SchedulingPriorityQueue {
std::priority_queue<SUnit*, std::vector<SUnit*>, SF> Queue;
public:
RegReductionPriorityQueue() :
Queue(SF(this)) {}
virtual void initNodes(std::vector<SUnit> &sunits) {}
virtual void releaseState() {}
virtual int getSethiUllmanNumber(unsigned NodeNum) const {
return 0;
}
bool empty() const { return Queue.empty(); }
void push(SUnit *U) {
Queue.push(U);
}
void push_all(const std::vector<SUnit *> &Nodes) {
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
Queue.push(Nodes[i]);
}
SUnit *pop() {
if (empty()) return NULL;
SUnit *V = Queue.top();
Queue.pop();
return V;
}
};
template<class SF>
class VISIBILITY_HIDDEN BURegReductionPriorityQueue
: public RegReductionPriorityQueue<SF> {
// SUnits - The SUnits for the current graph.
const std::vector<SUnit> *SUnits;
// SethiUllmanNumbers - The SethiUllman number for each node.
std::vector<int> SethiUllmanNumbers;
public:
BURegReductionPriorityQueue() {}
void initNodes(std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Add pseudo dependency edges for two-address nodes.
AddPseudoTwoAddrDeps();
// Calculate node priorities.
CalculatePriorities();
}
void releaseState() {
SUnits = 0;
SethiUllmanNumbers.clear();
}
int getSethiUllmanNumber(unsigned NodeNum) const {
assert(NodeNum < SethiUllmanNumbers.size());
return SethiUllmanNumbers[NodeNum];
}
private:
void AddPseudoTwoAddrDeps();
void CalculatePriorities();
int CalcNodePriority(const SUnit *SU);
};
template<class SF>
class TDRegReductionPriorityQueue : public RegReductionPriorityQueue<SF> {
// SUnits - The SUnits for the current graph.
const std::vector<SUnit> *SUnits;
// SethiUllmanNumbers - The SethiUllman number for each node.
std::vector<int> SethiUllmanNumbers;
public:
TDRegReductionPriorityQueue() {}
void initNodes(std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Calculate node priorities.
CalculatePriorities();
}
void releaseState() {
SUnits = 0;
SethiUllmanNumbers.clear();
}
int getSethiUllmanNumber(unsigned NodeNum) const {
assert(NodeNum < SethiUllmanNumbers.size());
return SethiUllmanNumbers[NodeNum];
}
private:
void CalculatePriorities();
int CalcNodePriority(const SUnit *SU);
};
}
static bool isFloater(const SUnit *SU) {
if (SU->Node->isTargetOpcode()) {
if (SU->NumPreds == 0)
return true;
if (SU->NumPreds == 1) {
for (SUnit::const_pred_iterator I = SU->Preds.begin(),E = SU->Preds.end();
I != E; ++I) {
if (I->second) continue;
SUnit *PredSU = I->first;
unsigned Opc = PredSU->Node->getOpcode();
if (Opc != ISD::EntryToken && Opc != ISD::TokenFactor &&
Opc != ISD::CopyFromReg && Opc != ISD::CopyToReg)
return false;
}
return true;
}
}
return false;
}
static bool isSimpleFloaterUse(const SUnit *SU) {
unsigned NumOps = 0;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->second) continue;
if (++NumOps > 1)
return false;
if (!isFloater(I->first))
return false;
}
return true;
}
// Bottom up
bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
unsigned LeftNum = left->NodeNum;
unsigned RightNum = right->NodeNum;
bool LIsTarget = left->Node->isTargetOpcode();
bool RIsTarget = right->Node->isTargetOpcode();
int LPriority = SPQ->getSethiUllmanNumber(LeftNum);
int RPriority = SPQ->getSethiUllmanNumber(RightNum);
int LBonus = 0;
int RBonus = 0;
// Schedule floaters (e.g. load from some constant address) and those nodes
// with a single predecessor each first. They maintain / reduce register
// pressure.
if (isFloater(left) || isSimpleFloaterUse(left))
LBonus += 2;
if (isFloater(right) || isSimpleFloaterUse(right))
RBonus += 2;
// Special tie breaker: if two nodes share a operand, the one that use it
// as a def&use operand is preferred.
if (LIsTarget && RIsTarget) {
if (left->isTwoAddress && !right->isTwoAddress) {
SDNode *DUNode = left->Node->getOperand(0).Val;
if (DUNode->isOperand(right->Node))
LBonus += 2;
}
if (!left->isTwoAddress && right->isTwoAddress) {
SDNode *DUNode = right->Node->getOperand(0).Val;
if (DUNode->isOperand(left->Node))
RBonus += 2;
}
}
if (LPriority+LBonus < RPriority+RBonus)
return true;
else if (LPriority+LBonus == RPriority+RBonus)
if (left->Height > right->Height)
return true;
else if (left->Height == right->Height)
if (left->Depth < right->Depth)
return true;
else if (left->Depth == right->Depth)
if (left->CycleBound > right->CycleBound)
return true;
return false;
}
static inline bool isCopyFromLiveIn(const SUnit *SU) {
SDNode *N = SU->Node;
return N->getOpcode() == ISD::CopyFromReg &&
N->getOperand(N->getNumOperands()-1).getValueType() != MVT::Flag;
}
// FIXME: This is probably too slow!
static void isReachable(SUnit *SU, SUnit *TargetSU,
std::set<SUnit *> &Visited, bool &Reached) {
if (Reached) return;
if (SU == TargetSU) {
Reached = true;
return;
}
if (!Visited.insert(SU).second) return;
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); I != E;
++I)
isReachable(I->first, TargetSU, Visited, Reached);
}
static bool isReachable(SUnit *SU, SUnit *TargetSU) {
std::set<SUnit *> Visited;
bool Reached = false;
isReachable(SU, TargetSU, Visited, Reached);
return Reached;
}
static SUnit *getDefUsePredecessor(SUnit *SU) {
SDNode *DU = SU->Node->getOperand(0).Val;
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->second) continue; // ignore chain preds
SUnit *PredSU = I->first;
if (PredSU->Node == DU)
return PredSU;
}
// Must be flagged.
return NULL;
}
static bool canClobber(SUnit *SU, SUnit *Op) {
if (SU->isTwoAddress)
return Op == getDefUsePredecessor(SU);
return false;
}
/// AddPseudoTwoAddrDeps - If two nodes share an operand and one of them uses
/// it as a def&use operand. Add a pseudo control edge from it to the other
/// node (if it won't create a cycle) so the two-address one will be scheduled
/// first (lower in the schedule).
template<class SF>
void BURegReductionPriorityQueue<SF>::AddPseudoTwoAddrDeps() {
for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
SUnit *SU = (SUnit *)&((*SUnits)[i]);
SDNode *Node = SU->Node;
if (!Node->isTargetOpcode())
continue;
if (SU->isTwoAddress) {
SUnit *DUSU = getDefUsePredecessor(SU);
if (!DUSU) continue;
for (SUnit::succ_iterator I = DUSU->Succs.begin(), E = DUSU->Succs.end();
I != E; ++I) {
if (I->second) continue;
SUnit *SuccSU = I->first;
if (SuccSU != SU &&
(!canClobber(SuccSU, DUSU) ||
(!SU->isCommutable && SuccSU->isCommutable))){
if (SuccSU->Depth == SU->Depth && !isReachable(SuccSU, SU)) {
DEBUG(std::cerr << "Adding an edge from SU # " << SU->NodeNum
<< " to SU #" << SuccSU->NodeNum << "\n");
if (SU->addPred(SuccSU, true))
SU->NumChainPredsLeft++;
if (SuccSU->addSucc(SU, true))
SuccSU->NumChainSuccsLeft++;
}
}
}
}
}
}
/// CalcNodePriority - Priority is the Sethi Ullman number.
/// Smaller number is the higher priority.
template<class SF>
int BURegReductionPriorityQueue<SF>::CalcNodePriority(const SUnit *SU) {
int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
if (SethiUllmanNumber != 0)
return SethiUllmanNumber;
unsigned Opc = SU->Node->getOpcode();
if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
SethiUllmanNumber = INT_MAX - 10;
else if (SU->NumSuccsLeft == 0)
// If SU does not have a use, i.e. it doesn't produce a value that would
// be consumed (e.g. store), then it terminates a chain of computation.
// Give it a small SethiUllman number so it will be scheduled right before its
// predecessors that it doesn't lengthen their live ranges.
SethiUllmanNumber = INT_MIN + 10;
// FIXME: remove this else if? It seems to reduce register spills but often
// ends up increasing runtime. Need to investigate.
else if (SU->NumPredsLeft == 0 &&
(Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
SethiUllmanNumber = INT_MAX - 10;
else {
int Extra = 0;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->second) continue; // ignore chain preds
SUnit *PredSU = I->first;
int PredSethiUllman = CalcNodePriority(PredSU);
if (PredSethiUllman > SethiUllmanNumber) {
SethiUllmanNumber = PredSethiUllman;
Extra = 0;
} else if (PredSethiUllman == SethiUllmanNumber && !I->second)
Extra++;
}
SethiUllmanNumber += Extra;
}
return SethiUllmanNumber;
}
/// CalculatePriorities - Calculate priorities of all scheduling units.
template<class SF>
void BURegReductionPriorityQueue<SF>::CalculatePriorities() {
SethiUllmanNumbers.assign(SUnits->size(), 0);
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
CalcNodePriority(&(*SUnits)[i]);
}
static unsigned SumOfUnscheduledPredsOfSuccs(const SUnit *SU) {
unsigned Sum = 0;
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
SUnit *SuccSU = I->first;
for (SUnit::const_pred_iterator II = SuccSU->Preds.begin(),
EE = SuccSU->Preds.end(); II != EE; ++II) {
SUnit *PredSU = II->first;
if (!PredSU->isScheduled)
Sum++;
}
}
return Sum;
}
// Top down
bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
unsigned LeftNum = left->NodeNum;
unsigned RightNum = right->NodeNum;
int LPriority = SPQ->getSethiUllmanNumber(LeftNum);
int RPriority = SPQ->getSethiUllmanNumber(RightNum);
bool LIsTarget = left->Node->isTargetOpcode();
bool RIsTarget = right->Node->isTargetOpcode();
bool LIsFloater = LIsTarget && left->NumPreds == 0;
bool RIsFloater = RIsTarget && right->NumPreds == 0;
unsigned LBonus = (SumOfUnscheduledPredsOfSuccs(left) == 1) ? 2 : 0;
unsigned RBonus = (SumOfUnscheduledPredsOfSuccs(right) == 1) ? 2 : 0;
if (left->NumSuccs == 0 && right->NumSuccs != 0)
return false;
else if (left->NumSuccs != 0 && right->NumSuccs == 0)
return true;
// Special tie breaker: if two nodes share a operand, the one that use it
// as a def&use operand is preferred.
if (LIsTarget && RIsTarget) {
if (left->isTwoAddress && !right->isTwoAddress) {
SDNode *DUNode = left->Node->getOperand(0).Val;
if (DUNode->isOperand(right->Node))
RBonus += 2;
}
if (!left->isTwoAddress && right->isTwoAddress) {
SDNode *DUNode = right->Node->getOperand(0).Val;
if (DUNode->isOperand(left->Node))
LBonus += 2;
}
}
if (LIsFloater)
LBonus -= 2;
if (RIsFloater)
RBonus -= 2;
if (left->NumSuccs == 1)
LBonus += 2;
if (right->NumSuccs == 1)
RBonus += 2;
if (LPriority+LBonus < RPriority+RBonus)
return true;
else if (LPriority == RPriority)
if (left->Depth < right->Depth)
return true;
else if (left->Depth == right->Depth)
if (left->NumSuccsLeft > right->NumSuccsLeft)
return true;
else if (left->NumSuccsLeft == right->NumSuccsLeft)
if (left->CycleBound > right->CycleBound)
return true;
return false;
}
/// CalcNodePriority - Priority is the Sethi Ullman number.
/// Smaller number is the higher priority.
template<class SF>
int TDRegReductionPriorityQueue<SF>::CalcNodePriority(const SUnit *SU) {
int &SethiUllmanNumber = SethiUllmanNumbers[SU->NodeNum];
if (SethiUllmanNumber != 0)
return SethiUllmanNumber;
unsigned Opc = SU->Node->getOpcode();
if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
SethiUllmanNumber = INT_MAX - 10;
else if (SU->NumSuccsLeft == 0)
// If SU does not have a use, i.e. it doesn't produce a value that would
// be consumed (e.g. store), then it terminates a chain of computation.
// Give it a small SethiUllman number so it will be scheduled right before its
// predecessors that it doesn't lengthen their live ranges.
SethiUllmanNumber = INT_MIN + 10;
else if (SU->NumPredsLeft == 0 &&
(Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
SethiUllmanNumber = 1;
else {
int Extra = 0;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->second) continue; // ignore chain preds
SUnit *PredSU = I->first;
int PredSethiUllman = CalcNodePriority(PredSU);
if (PredSethiUllman > SethiUllmanNumber) {
SethiUllmanNumber = PredSethiUllman;
Extra = 0;
} else if (PredSethiUllman == SethiUllmanNumber && !I->second)
Extra++;
}
SethiUllmanNumber += Extra;
}
return SethiUllmanNumber;
}
/// CalculatePriorities - Calculate priorities of all scheduling units.
template<class SF>
void TDRegReductionPriorityQueue<SF>::CalculatePriorities() {
SethiUllmanNumbers.assign(SUnits->size(), 0);
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
CalcNodePriority(&(*SUnits)[i]);
}
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB) {
return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), true,
new BURegReductionPriorityQueue<bu_ls_rr_sort>());
}
llvm::ScheduleDAG* llvm::createTDRRListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB) {
return new ScheduleDAGRRList(*DAG, BB, DAG->getTarget(), false,
new TDRegReductionPriorityQueue<td_ls_rr_sort>());
}
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