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llvm-mirror/lib/CodeGen/SelectionDAG/ScheduleDAGRRList.cpp
Dan Gohman 291ea92cc4 In ScheduleDAGRRList::CopyAndMoveSuccessors, create the SUnit for the load 
before creating the SUnit for the operation that it was unfolded from. This
allows each SUnit to have all of its predecessor SUnits available at the time
it is created. I don't know yet if this will be absolutely required, but it
is a little tidier to do it this way.

llvm-svn: 59083
2008-11-11 21:34:44 +00:00

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//===----- ScheduleDAGRRList.cpp - Reg pressure reduction 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 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 "pre-RA-sched"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/SchedulerRegistry.h"
#include "llvm/Target/TargetRegisterInfo.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/BitVector.h"
#include "llvm/ADT/PriorityQueue.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include <climits>
#include "llvm/Support/CommandLine.h"
using namespace llvm;
STATISTIC(NumBacktracks, "Number of times scheduler backtracked");
STATISTIC(NumUnfolds, "Number of nodes unfolded");
STATISTIC(NumDups, "Number of duplicated nodes");
STATISTIC(NumCCCopies, "Number of cross class copies");
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;
/// Fast - True if we are performing fast scheduling.
///
bool Fast;
/// AvailableQueue - The priority queue to use for the available SUnits.
SchedulingPriorityQueue *AvailableQueue;
/// LiveRegDefs - A set of physical registers and their definition
/// that are "live". These nodes must be scheduled before any other nodes that
/// modifies the registers can be scheduled.
unsigned NumLiveRegs;
std::vector<SUnit*> LiveRegDefs;
std::vector<unsigned> LiveRegCycles;
public:
ScheduleDAGRRList(SelectionDAG &dag, MachineBasicBlock *bb,
const TargetMachine &tm, bool isbottomup, bool f,
SchedulingPriorityQueue *availqueue)
: ScheduleDAG(dag, bb, tm), isBottomUp(isbottomup), Fast(f),
AvailableQueue(availqueue) {
}
~ScheduleDAGRRList() {
delete AvailableQueue;
}
void Schedule();
/// IsReachable - Checks if SU is reachable from TargetSU.
bool IsReachable(const SUnit *SU, const SUnit *TargetSU);
/// willCreateCycle - Returns true if adding an edge from SU to TargetSU will
/// create a cycle.
bool WillCreateCycle(SUnit *SU, SUnit *TargetSU);
/// AddPred - This adds the specified node X as a predecessor of
/// the current node Y if not already.
/// This returns true if this is a new predecessor.
/// Updates the topological ordering if required.
bool AddPred(SUnit *Y, SUnit *X, bool isCtrl, bool isSpecial,
unsigned PhyReg = 0, int Cost = 1);
/// RemovePred - This removes the specified node N from the predecessors of
/// the current node M. Updates the topological ordering if required.
bool RemovePred(SUnit *M, SUnit *N, bool isCtrl, bool isSpecial);
private:
void ReleasePred(SUnit*, bool, unsigned);
void ReleaseSucc(SUnit*, bool isChain, unsigned);
void CapturePred(SUnit*, SUnit*, bool);
void ScheduleNodeBottomUp(SUnit*, unsigned);
void ScheduleNodeTopDown(SUnit*, unsigned);
void UnscheduleNodeBottomUp(SUnit*);
void BacktrackBottomUp(SUnit*, unsigned, unsigned&);
SUnit *CopyAndMoveSuccessors(SUnit*);
void InsertCCCopiesAndMoveSuccs(SUnit*, unsigned,
const TargetRegisterClass*,
const TargetRegisterClass*,
SmallVector<SUnit*, 2>&);
bool DelayForLiveRegsBottomUp(SUnit*, SmallVector<unsigned, 4>&);
void ListScheduleTopDown();
void ListScheduleBottomUp();
void CommuteNodesToReducePressure();
/// CreateNewSUnit - Creates a new SUnit and returns a pointer to it.
/// Updates the topological ordering if required.
SUnit *CreateNewSUnit(SDNode *N) {
SUnit *NewNode = NewSUnit(N);
// Update the topological ordering.
if (NewNode->NodeNum >= Node2Index.size())
InitDAGTopologicalSorting();
return NewNode;
}
/// CreateClone - Creates a new SUnit from an existing one.
/// Updates the topological ordering if required.
SUnit *CreateClone(SUnit *N) {
SUnit *NewNode = Clone(N);
// Update the topological ordering.
if (NewNode->NodeNum >= Node2Index.size())
InitDAGTopologicalSorting();
return NewNode;
}
/// Functions for preserving the topological ordering
/// even after dynamic insertions of new edges.
/// This allows a very fast implementation of IsReachable.
/// InitDAGTopologicalSorting - create the initial topological
/// ordering from the DAG to be scheduled.
void InitDAGTopologicalSorting();
/// DFS - make a DFS traversal and mark all nodes affected by the
/// edge insertion. These nodes will later get new topological indexes
/// by means of the Shift method.
void DFS(const SUnit *SU, int UpperBound, bool& HasLoop);
/// Shift - reassign topological indexes for the nodes in the DAG
/// to preserve the topological ordering.
void Shift(BitVector& Visited, int LowerBound, int UpperBound);
/// Allocate - assign the topological index to the node n.
void Allocate(int n, int index);
/// Index2Node - Maps topological index to the node number.
std::vector<int> Index2Node;
/// Node2Index - Maps the node number to its topological index.
std::vector<int> Node2Index;
/// Visited - a set of nodes visited during a DFS traversal.
BitVector Visited;
};
} // end anonymous namespace
/// Schedule - Schedule the DAG using list scheduling.
void ScheduleDAGRRList::Schedule() {
DOUT << "********** List Scheduling **********\n";
NumLiveRegs = 0;
LiveRegDefs.resize(TRI->getNumRegs(), NULL);
LiveRegCycles.resize(TRI->getNumRegs(), 0);
// Build scheduling units.
BuildSchedUnits();
DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su)
SUnits[su].dumpAll(&DAG));
if (!Fast) {
CalculateDepths();
CalculateHeights();
}
InitDAGTopologicalSorting();
AvailableQueue->initNodes(SUnits);
// Execute the actual scheduling loop Top-Down or Bottom-Up as appropriate.
if (isBottomUp)
ListScheduleBottomUp();
else
ListScheduleTopDown();
AvailableQueue->releaseState();
if (!Fast)
CommuteNodesToReducePressure();
}
/// CommuteNodesToReducePressure - If 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() {
SmallPtrSet<SUnit*, 4> OperandSeen;
for (unsigned i = Sequence.size(); i != 0; ) {
--i;
SUnit *SU = Sequence[i];
if (!SU || !SU->Node) continue;
if (SU->isCommutable) {
unsigned Opc = SU->Node->getMachineOpcode();
const TargetInstrDesc &TID = TII->get(Opc);
unsigned NumRes = TID.getNumDefs();
unsigned NumOps = TID.getNumOperands() - NumRes;
for (unsigned j = 0; j != NumOps; ++j) {
if (TID.getOperandConstraint(j+NumRes, TOI::TIED_TO) == -1)
continue;
SDNode *OpN = SU->Node->getOperand(j).getNode();
SUnit *OpSU = isPassiveNode(OpN) ? NULL : &SUnits[OpN->getNodeId()];
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 SU if no other source operands
// are live below.
bool DoCommute = true;
for (unsigned k = 0; k < NumOps; ++k) {
if (k != j) {
OpN = SU->Node->getOperand(k).getNode();
OpSU = isPassiveNode(OpN) ? NULL : &SUnits[OpN->getNodeId()];
if (OpSU && OperandSeen.count(OpSU) == 1) {
DoCommute = false;
break;
}
}
}
if (DoCommute)
CommuteSet.insert(SU->Node);
}
// Only look at the first use&def node for now.
break;
}
}
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (!I->isCtrl)
OperandSeen.insert(I->Dep->OrigNode);
}
}
}
//===----------------------------------------------------------------------===//
// Bottom-Up Scheduling
//===----------------------------------------------------------------------===//
/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. Add it to
/// the AvailableQueue if 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);
--PredSU->NumSuccsLeft;
#ifndef NDEBUG
if (PredSU->NumSuccsLeft < 0) {
cerr << "*** List scheduling failed! ***\n";
PredSU->dump(&DAG);
cerr << " has been released too many times!\n";
assert(0);
}
#endif
if (PredSU->NumSuccsLeft == 0) {
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) {
DOUT << "*** Scheduling [" << CurCycle << "]: ";
DEBUG(SU->dump(&DAG));
SU->Cycle = CurCycle;
AvailableQueue->ScheduledNode(SU);
// Bottom up: release predecessors
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
ReleasePred(I->Dep, I->isCtrl, CurCycle);
if (I->Cost < 0) {
// This is a physical register dependency and it's impossible or
// expensive to copy the register. Make sure nothing that can
// clobber the register is scheduled between the predecessor and
// this node.
if (!LiveRegDefs[I->Reg]) {
++NumLiveRegs;
LiveRegDefs[I->Reg] = I->Dep;
LiveRegCycles[I->Reg] = CurCycle;
}
}
}
// Release all the implicit physical register defs that are live.
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->Cost < 0) {
if (LiveRegCycles[I->Reg] == I->Dep->Cycle) {
assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!");
assert(LiveRegDefs[I->Reg] == SU &&
"Physical register dependency violated?");
--NumLiveRegs;
LiveRegDefs[I->Reg] = NULL;
LiveRegCycles[I->Reg] = 0;
}
}
}
SU->isScheduled = true;
}
/// CapturePred - This does the opposite of ReleasePred. Since SU is being
/// unscheduled, incrcease the succ left count of its predecessors. Remove
/// them from AvailableQueue if necessary.
void ScheduleDAGRRList::CapturePred(SUnit *PredSU, SUnit *SU, bool isChain) {
unsigned CycleBound = 0;
for (SUnit::succ_iterator I = PredSU->Succs.begin(), E = PredSU->Succs.end();
I != E; ++I) {
if (I->Dep == SU)
continue;
CycleBound = std::max(CycleBound,
I->Dep->Cycle + PredSU->Latency);
}
if (PredSU->isAvailable) {
PredSU->isAvailable = false;
if (!PredSU->isPending)
AvailableQueue->remove(PredSU);
}
PredSU->CycleBound = CycleBound;
++PredSU->NumSuccsLeft;
}
/// UnscheduleNodeBottomUp - Remove the node from the schedule, update its and
/// its predecessor states to reflect the change.
void ScheduleDAGRRList::UnscheduleNodeBottomUp(SUnit *SU) {
DOUT << "*** Unscheduling [" << SU->Cycle << "]: ";
DEBUG(SU->dump(&DAG));
AvailableQueue->UnscheduledNode(SU);
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
CapturePred(I->Dep, SU, I->isCtrl);
if (I->Cost < 0 && SU->Cycle == LiveRegCycles[I->Reg]) {
assert(NumLiveRegs > 0 && "NumLiveRegs is already zero!");
assert(LiveRegDefs[I->Reg] == I->Dep &&
"Physical register dependency violated?");
--NumLiveRegs;
LiveRegDefs[I->Reg] = NULL;
LiveRegCycles[I->Reg] = 0;
}
}
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->Cost < 0) {
if (!LiveRegDefs[I->Reg]) {
LiveRegDefs[I->Reg] = SU;
++NumLiveRegs;
}
if (I->Dep->Cycle < LiveRegCycles[I->Reg])
LiveRegCycles[I->Reg] = I->Dep->Cycle;
}
}
SU->Cycle = 0;
SU->isScheduled = false;
SU->isAvailable = true;
AvailableQueue->push(SU);
}
/// IsReachable - Checks if SU is reachable from TargetSU.
bool ScheduleDAGRRList::IsReachable(const SUnit *SU, const SUnit *TargetSU) {
// If insertion of the edge SU->TargetSU would create a cycle
// then there is a path from TargetSU to SU.
int UpperBound, LowerBound;
LowerBound = Node2Index[TargetSU->NodeNum];
UpperBound = Node2Index[SU->NodeNum];
bool HasLoop = false;
// Is Ord(TargetSU) < Ord(SU) ?
if (LowerBound < UpperBound) {
Visited.reset();
// There may be a path from TargetSU to SU. Check for it.
DFS(TargetSU, UpperBound, HasLoop);
}
return HasLoop;
}
/// Allocate - assign the topological index to the node n.
inline void ScheduleDAGRRList::Allocate(int n, int index) {
Node2Index[n] = index;
Index2Node[index] = n;
}
/// InitDAGTopologicalSorting - create the initial topological
/// ordering from the DAG to be scheduled.
/// The idea of the algorithm is taken from
/// "Online algorithms for managing the topological order of
/// a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly
/// This is the MNR algorithm, which was first introduced by
/// A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in
/// "Maintaining a topological order under edge insertions".
///
/// Short description of the algorithm:
///
/// Topological ordering, ord, of a DAG maps each node to a topological
/// index so that for all edges X->Y it is the case that ord(X) < ord(Y).
///
/// This means that if there is a path from the node X to the node Z,
/// then ord(X) < ord(Z).
///
/// This property can be used to check for reachability of nodes:
/// if Z is reachable from X, then an insertion of the edge Z->X would
/// create a cycle.
///
/// The algorithm first computes a topological ordering for the DAG by
/// initializing the Index2Node and Node2Index arrays and then tries to keep
/// the ordering up-to-date after edge insertions by reordering the DAG.
///
/// On insertion of the edge X->Y, the algorithm first marks by calling DFS
/// the nodes reachable from Y, and then shifts them using Shift to lie
/// immediately after X in Index2Node.
void ScheduleDAGRRList::InitDAGTopologicalSorting() {
unsigned DAGSize = SUnits.size();
std::vector<SUnit*> WorkList;
WorkList.reserve(DAGSize);
Index2Node.resize(DAGSize);
Node2Index.resize(DAGSize);
// Initialize the data structures.
for (unsigned i = 0, e = DAGSize; i != e; ++i) {
SUnit *SU = &SUnits[i];
int NodeNum = SU->NodeNum;
unsigned Degree = SU->Succs.size();
// Temporarily use the Node2Index array as scratch space for degree counts.
Node2Index[NodeNum] = Degree;
// Is it a node without dependencies?
if (Degree == 0) {
assert(SU->Succs.empty() && "SUnit should have no successors");
// Collect leaf nodes.
WorkList.push_back(SU);
}
}
int Id = DAGSize;
while (!WorkList.empty()) {
SUnit *SU = WorkList.back();
WorkList.pop_back();
Allocate(SU->NodeNum, --Id);
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
SUnit *SU = I->Dep;
if (!--Node2Index[SU->NodeNum])
// If all dependencies of the node are processed already,
// then the node can be computed now.
WorkList.push_back(SU);
}
}
Visited.resize(DAGSize);
#ifndef NDEBUG
// Check correctness of the ordering
for (unsigned i = 0, e = DAGSize; i != e; ++i) {
SUnit *SU = &SUnits[i];
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
assert(Node2Index[SU->NodeNum] > Node2Index[I->Dep->NodeNum] &&
"Wrong topological sorting");
}
}
#endif
}
/// AddPred - adds an edge from SUnit X to SUnit Y.
/// Updates the topological ordering if required.
bool ScheduleDAGRRList::AddPred(SUnit *Y, SUnit *X, bool isCtrl, bool isSpecial,
unsigned PhyReg, int Cost) {
int UpperBound, LowerBound;
LowerBound = Node2Index[Y->NodeNum];
UpperBound = Node2Index[X->NodeNum];
bool HasLoop = false;
// Is Ord(X) < Ord(Y) ?
if (LowerBound < UpperBound) {
// Update the topological order.
Visited.reset();
DFS(Y, UpperBound, HasLoop);
assert(!HasLoop && "Inserted edge creates a loop!");
// Recompute topological indexes.
Shift(Visited, LowerBound, UpperBound);
}
// Now really insert the edge.
return Y->addPred(X, isCtrl, isSpecial, PhyReg, Cost);
}
/// RemovePred - This removes the specified node N from the predecessors of
/// the current node M. Updates the topological ordering if required.
bool ScheduleDAGRRList::RemovePred(SUnit *M, SUnit *N,
bool isCtrl, bool isSpecial) {
// InitDAGTopologicalSorting();
return M->removePred(N, isCtrl, isSpecial);
}
/// DFS - Make a DFS traversal to mark all nodes reachable from SU and mark
/// all nodes affected by the edge insertion. These nodes will later get new
/// topological indexes by means of the Shift method.
void ScheduleDAGRRList::DFS(const SUnit *SU, int UpperBound, bool& HasLoop) {
std::vector<const SUnit*> WorkList;
WorkList.reserve(SUnits.size());
WorkList.push_back(SU);
while (!WorkList.empty()) {
SU = WorkList.back();
WorkList.pop_back();
Visited.set(SU->NodeNum);
for (int I = SU->Succs.size()-1; I >= 0; --I) {
int s = SU->Succs[I].Dep->NodeNum;
if (Node2Index[s] == UpperBound) {
HasLoop = true;
return;
}
// Visit successors if not already and in affected region.
if (!Visited.test(s) && Node2Index[s] < UpperBound) {
WorkList.push_back(SU->Succs[I].Dep);
}
}
}
}
/// Shift - Renumber the nodes so that the topological ordering is
/// preserved.
void ScheduleDAGRRList::Shift(BitVector& Visited, int LowerBound,
int UpperBound) {
std::vector<int> L;
int shift = 0;
int i;
for (i = LowerBound; i <= UpperBound; ++i) {
// w is node at topological index i.
int w = Index2Node[i];
if (Visited.test(w)) {
// Unmark.
Visited.reset(w);
L.push_back(w);
shift = shift + 1;
} else {
Allocate(w, i - shift);
}
}
for (unsigned j = 0; j < L.size(); ++j) {
Allocate(L[j], i - shift);
i = i + 1;
}
}
/// WillCreateCycle - Returns true if adding an edge from SU to TargetSU will
/// create a cycle.
bool ScheduleDAGRRList::WillCreateCycle(SUnit *SU, SUnit *TargetSU) {
if (IsReachable(TargetSU, SU))
return true;
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I)
if (I->Cost < 0 && IsReachable(TargetSU, I->Dep))
return true;
return false;
}
/// BacktrackBottomUp - Backtrack scheduling to a previous cycle specified in
/// BTCycle in order to schedule a specific node. Returns the last unscheduled
/// SUnit. Also returns if a successor is unscheduled in the process.
void ScheduleDAGRRList::BacktrackBottomUp(SUnit *SU, unsigned BtCycle,
unsigned &CurCycle) {
SUnit *OldSU = NULL;
while (CurCycle > BtCycle) {
OldSU = Sequence.back();
Sequence.pop_back();
if (SU->isSucc(OldSU))
// Don't try to remove SU from AvailableQueue.
SU->isAvailable = false;
UnscheduleNodeBottomUp(OldSU);
--CurCycle;
}
if (SU->isSucc(OldSU)) {
assert(false && "Something is wrong!");
abort();
}
++NumBacktracks;
}
/// CopyAndMoveSuccessors - Clone the specified node and move its scheduled
/// successors to the newly created node.
SUnit *ScheduleDAGRRList::CopyAndMoveSuccessors(SUnit *SU) {
if (SU->FlaggedNodes.size())
return NULL;
SDNode *N = SU->Node;
if (!N)
return NULL;
SUnit *NewSU;
bool TryUnfold = false;
for (unsigned i = 0, e = N->getNumValues(); i != e; ++i) {
MVT VT = N->getValueType(i);
if (VT == MVT::Flag)
return NULL;
else if (VT == MVT::Other)
TryUnfold = true;
}
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
const SDValue &Op = N->getOperand(i);
MVT VT = Op.getNode()->getValueType(Op.getResNo());
if (VT == MVT::Flag)
return NULL;
}
if (TryUnfold) {
SmallVector<SDNode*, 2> NewNodes;
if (!TII->unfoldMemoryOperand(DAG, N, NewNodes))
return NULL;
DOUT << "Unfolding SU # " << SU->NodeNum << "\n";
assert(NewNodes.size() == 2 && "Expected a load folding node!");
N = NewNodes[1];
SDNode *LoadNode = NewNodes[0];
unsigned NumVals = N->getNumValues();
unsigned OldNumVals = SU->Node->getNumValues();
for (unsigned i = 0; i != NumVals; ++i)
DAG.ReplaceAllUsesOfValueWith(SDValue(SU->Node, i), SDValue(N, i));
DAG.ReplaceAllUsesOfValueWith(SDValue(SU->Node, OldNumVals-1),
SDValue(LoadNode, 1));
// LoadNode may already exist. This can happen when there is another
// load from the same location and producing the same type of value
// but it has different alignment or volatileness.
bool isNewLoad = true;
SUnit *LoadSU;
if (LoadNode->getNodeId() != -1) {
LoadSU = &SUnits[LoadNode->getNodeId()];
isNewLoad = false;
} else {
LoadSU = CreateNewSUnit(LoadNode);
LoadNode->setNodeId(LoadSU->NodeNum);
LoadSU->Depth = SU->Depth;
LoadSU->Height = SU->Height;
ComputeLatency(LoadSU);
}
SUnit *NewSU = CreateNewSUnit(N);
assert(N->getNodeId() == -1 && "Node already inserted!");
N->setNodeId(NewSU->NodeNum);
const TargetInstrDesc &TID = TII->get(N->getMachineOpcode());
for (unsigned i = 0; i != TID.getNumOperands(); ++i) {
if (TID.getOperandConstraint(i, TOI::TIED_TO) != -1) {
NewSU->isTwoAddress = true;
break;
}
}
if (TID.isCommutable())
NewSU->isCommutable = true;
// FIXME: Calculate height / depth and propagate the changes?
NewSU->Depth = SU->Depth;
NewSU->Height = SU->Height;
ComputeLatency(NewSU);
SUnit *ChainPred = NULL;
SmallVector<SDep, 4> ChainSuccs;
SmallVector<SDep, 4> LoadPreds;
SmallVector<SDep, 4> NodePreds;
SmallVector<SDep, 4> NodeSuccs;
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl)
ChainPred = I->Dep;
else if (I->Dep->Node && I->Dep->Node->isOperandOf(LoadNode))
LoadPreds.push_back(SDep(I->Dep, I->Reg, I->Cost, false, false));
else
NodePreds.push_back(SDep(I->Dep, I->Reg, I->Cost, false, false));
}
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->isCtrl)
ChainSuccs.push_back(SDep(I->Dep, I->Reg, I->Cost,
I->isCtrl, I->isSpecial));
else
NodeSuccs.push_back(SDep(I->Dep, I->Reg, I->Cost,
I->isCtrl, I->isSpecial));
}
if (ChainPred) {
RemovePred(SU, ChainPred, true, false);
if (isNewLoad)
AddPred(LoadSU, ChainPred, true, false);
}
for (unsigned i = 0, e = LoadPreds.size(); i != e; ++i) {
SDep *Pred = &LoadPreds[i];
RemovePred(SU, Pred->Dep, Pred->isCtrl, Pred->isSpecial);
if (isNewLoad) {
AddPred(LoadSU, Pred->Dep, Pred->isCtrl, Pred->isSpecial,
Pred->Reg, Pred->Cost);
}
}
for (unsigned i = 0, e = NodePreds.size(); i != e; ++i) {
SDep *Pred = &NodePreds[i];
RemovePred(SU, Pred->Dep, Pred->isCtrl, Pred->isSpecial);
AddPred(NewSU, Pred->Dep, Pred->isCtrl, Pred->isSpecial,
Pred->Reg, Pred->Cost);
}
for (unsigned i = 0, e = NodeSuccs.size(); i != e; ++i) {
SDep *Succ = &NodeSuccs[i];
RemovePred(Succ->Dep, SU, Succ->isCtrl, Succ->isSpecial);
AddPred(Succ->Dep, NewSU, Succ->isCtrl, Succ->isSpecial,
Succ->Reg, Succ->Cost);
}
for (unsigned i = 0, e = ChainSuccs.size(); i != e; ++i) {
SDep *Succ = &ChainSuccs[i];
RemovePred(Succ->Dep, SU, Succ->isCtrl, Succ->isSpecial);
if (isNewLoad) {
AddPred(Succ->Dep, LoadSU, Succ->isCtrl, Succ->isSpecial,
Succ->Reg, Succ->Cost);
}
}
if (isNewLoad) {
AddPred(NewSU, LoadSU, false, false);
}
if (isNewLoad)
AvailableQueue->addNode(LoadSU);
AvailableQueue->addNode(NewSU);
++NumUnfolds;
if (NewSU->NumSuccsLeft == 0) {
NewSU->isAvailable = true;
return NewSU;
}
SU = NewSU;
}
DOUT << "Duplicating SU # " << SU->NodeNum << "\n";
NewSU = CreateClone(SU);
// New SUnit has the exact same predecessors.
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I)
if (!I->isSpecial) {
AddPred(NewSU, I->Dep, I->isCtrl, false, I->Reg, I->Cost);
NewSU->Depth = std::max(NewSU->Depth, I->Dep->Depth+1);
}
// Only copy scheduled successors. Cut them from old node's successor
// list and move them over.
SmallVector<std::pair<SUnit*, bool>, 4> DelDeps;
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->isSpecial)
continue;
if (I->Dep->isScheduled) {
NewSU->Height = std::max(NewSU->Height, I->Dep->Height+1);
AddPred(I->Dep, NewSU, I->isCtrl, false, I->Reg, I->Cost);
DelDeps.push_back(std::make_pair(I->Dep, I->isCtrl));
}
}
for (unsigned i = 0, e = DelDeps.size(); i != e; ++i) {
SUnit *Succ = DelDeps[i].first;
bool isCtrl = DelDeps[i].second;
RemovePred(Succ, SU, isCtrl, false);
}
AvailableQueue->updateNode(SU);
AvailableQueue->addNode(NewSU);
++NumDups;
return NewSU;
}
/// InsertCCCopiesAndMoveSuccs - Insert expensive cross register class copies
/// and move all scheduled successors of the given SUnit to the last copy.
void ScheduleDAGRRList::InsertCCCopiesAndMoveSuccs(SUnit *SU, unsigned Reg,
const TargetRegisterClass *DestRC,
const TargetRegisterClass *SrcRC,
SmallVector<SUnit*, 2> &Copies) {
SUnit *CopyFromSU = CreateNewSUnit(NULL);
CopyFromSU->CopySrcRC = SrcRC;
CopyFromSU->CopyDstRC = DestRC;
CopyFromSU->Depth = SU->Depth;
CopyFromSU->Height = SU->Height;
SUnit *CopyToSU = CreateNewSUnit(NULL);
CopyToSU->CopySrcRC = DestRC;
CopyToSU->CopyDstRC = SrcRC;
// Only copy scheduled successors. Cut them from old node's successor
// list and move them over.
SmallVector<std::pair<SUnit*, bool>, 4> DelDeps;
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->isSpecial)
continue;
if (I->Dep->isScheduled) {
CopyToSU->Height = std::max(CopyToSU->Height, I->Dep->Height+1);
AddPred(I->Dep, CopyToSU, I->isCtrl, false, I->Reg, I->Cost);
DelDeps.push_back(std::make_pair(I->Dep, I->isCtrl));
}
}
for (unsigned i = 0, e = DelDeps.size(); i != e; ++i) {
SUnit *Succ = DelDeps[i].first;
bool isCtrl = DelDeps[i].second;
RemovePred(Succ, SU, isCtrl, false);
}
AddPred(CopyFromSU, SU, false, false, Reg, -1);
AddPred(CopyToSU, CopyFromSU, false, false, Reg, 1);
AvailableQueue->updateNode(SU);
AvailableQueue->addNode(CopyFromSU);
AvailableQueue->addNode(CopyToSU);
Copies.push_back(CopyFromSU);
Copies.push_back(CopyToSU);
++NumCCCopies;
}
/// getPhysicalRegisterVT - Returns the ValueType of the physical register
/// definition of the specified node.
/// FIXME: Move to SelectionDAG?
static MVT getPhysicalRegisterVT(SDNode *N, unsigned Reg,
const TargetInstrInfo *TII) {
const TargetInstrDesc &TID = TII->get(N->getMachineOpcode());
assert(TID.ImplicitDefs && "Physical reg def must be in implicit def list!");
unsigned NumRes = TID.getNumDefs();
for (const unsigned *ImpDef = TID.getImplicitDefs(); *ImpDef; ++ImpDef) {
if (Reg == *ImpDef)
break;
++NumRes;
}
return N->getValueType(NumRes);
}
/// DelayForLiveRegsBottomUp - Returns true if it is necessary to delay
/// scheduling of the given node to satisfy live physical register dependencies.
/// If the specific node is the last one that's available to schedule, do
/// whatever is necessary (i.e. backtracking or cloning) to make it possible.
bool ScheduleDAGRRList::DelayForLiveRegsBottomUp(SUnit *SU,
SmallVector<unsigned, 4> &LRegs){
if (NumLiveRegs == 0)
return false;
SmallSet<unsigned, 4> RegAdded;
// If this node would clobber any "live" register, then it's not ready.
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->Cost < 0) {
unsigned Reg = I->Reg;
if (LiveRegDefs[Reg] && LiveRegDefs[Reg] != I->Dep) {
if (RegAdded.insert(Reg))
LRegs.push_back(Reg);
}
for (const unsigned *Alias = TRI->getAliasSet(Reg);
*Alias; ++Alias)
if (LiveRegDefs[*Alias] && LiveRegDefs[*Alias] != I->Dep) {
if (RegAdded.insert(*Alias))
LRegs.push_back(*Alias);
}
}
}
for (unsigned i = 0, e = SU->FlaggedNodes.size()+1; i != e; ++i) {
SDNode *Node = (i == 0) ? SU->Node : SU->FlaggedNodes[i-1];
if (!Node || !Node->isMachineOpcode())
continue;
const TargetInstrDesc &TID = TII->get(Node->getMachineOpcode());
if (!TID.ImplicitDefs)
continue;
for (const unsigned *Reg = TID.ImplicitDefs; *Reg; ++Reg) {
if (LiveRegDefs[*Reg] && LiveRegDefs[*Reg] != SU) {
if (RegAdded.insert(*Reg))
LRegs.push_back(*Reg);
}
for (const unsigned *Alias = TRI->getAliasSet(*Reg);
*Alias; ++Alias)
if (LiveRegDefs[*Alias] && LiveRegDefs[*Alias] != SU) {
if (RegAdded.insert(*Alias))
LRegs.push_back(*Alias);
}
}
}
return !LRegs.empty();
}
/// ListScheduleBottomUp - The main loop of list scheduling for bottom-up
/// schedulers.
void ScheduleDAGRRList::ListScheduleBottomUp() {
unsigned CurCycle = 0;
// Add root to Available queue.
if (!SUnits.empty()) {
SUnit *RootSU = &SUnits[DAG.getRoot().getNode()->getNodeId()];
assert(RootSU->Succs.empty() && "Graph root shouldn't have successors!");
RootSU->isAvailable = true;
AvailableQueue->push(RootSU);
}
// While Available queue is not empty, grab the node with the highest
// priority. If it is not ready put it back. Schedule the node.
SmallVector<SUnit*, 4> NotReady;
DenseMap<SUnit*, SmallVector<unsigned, 4> > LRegsMap;
Sequence.reserve(SUnits.size());
while (!AvailableQueue->empty()) {
bool Delayed = false;
LRegsMap.clear();
SUnit *CurSU = AvailableQueue->pop();
while (CurSU) {
if (CurSU->CycleBound <= CurCycle) {
SmallVector<unsigned, 4> LRegs;
if (!DelayForLiveRegsBottomUp(CurSU, LRegs))
break;
Delayed = true;
LRegsMap.insert(std::make_pair(CurSU, LRegs));
}
CurSU->isPending = true; // This SU is not in AvailableQueue right now.
NotReady.push_back(CurSU);
CurSU = AvailableQueue->pop();
}
// All candidates are delayed due to live physical reg dependencies.
// Try backtracking, code duplication, or inserting cross class copies
// to resolve it.
if (Delayed && !CurSU) {
for (unsigned i = 0, e = NotReady.size(); i != e; ++i) {
SUnit *TrySU = NotReady[i];
SmallVector<unsigned, 4> &LRegs = LRegsMap[TrySU];
// Try unscheduling up to the point where it's safe to schedule
// this node.
unsigned LiveCycle = CurCycle;
for (unsigned j = 0, ee = LRegs.size(); j != ee; ++j) {
unsigned Reg = LRegs[j];
unsigned LCycle = LiveRegCycles[Reg];
LiveCycle = std::min(LiveCycle, LCycle);
}
SUnit *OldSU = Sequence[LiveCycle];
if (!WillCreateCycle(TrySU, OldSU)) {
BacktrackBottomUp(TrySU, LiveCycle, CurCycle);
// Force the current node to be scheduled before the node that
// requires the physical reg dep.
if (OldSU->isAvailable) {
OldSU->isAvailable = false;
AvailableQueue->remove(OldSU);
}
AddPred(TrySU, OldSU, true, true);
// If one or more successors has been unscheduled, then the current
// node is no longer avaialable. Schedule a successor that's now
// available instead.
if (!TrySU->isAvailable)
CurSU = AvailableQueue->pop();
else {
CurSU = TrySU;
TrySU->isPending = false;
NotReady.erase(NotReady.begin()+i);
}
break;
}
}
if (!CurSU) {
// Can't backtrack. Try duplicating the nodes that produces these
// "expensive to copy" values to break the dependency. In case even
// that doesn't work, insert cross class copies.
SUnit *TrySU = NotReady[0];
SmallVector<unsigned, 4> &LRegs = LRegsMap[TrySU];
assert(LRegs.size() == 1 && "Can't handle this yet!");
unsigned Reg = LRegs[0];
SUnit *LRDef = LiveRegDefs[Reg];
SUnit *NewDef = CopyAndMoveSuccessors(LRDef);
if (!NewDef) {
// Issue expensive cross register class copies.
MVT VT = getPhysicalRegisterVT(LRDef->Node, Reg, TII);
const TargetRegisterClass *RC =
TRI->getPhysicalRegisterRegClass(Reg, VT);
const TargetRegisterClass *DestRC = TRI->getCrossCopyRegClass(RC);
if (!DestRC) {
assert(false && "Don't know how to copy this physical register!");
abort();
}
SmallVector<SUnit*, 2> Copies;
InsertCCCopiesAndMoveSuccs(LRDef, Reg, DestRC, RC, Copies);
DOUT << "Adding an edge from SU # " << TrySU->NodeNum
<< " to SU #" << Copies.front()->NodeNum << "\n";
AddPred(TrySU, Copies.front(), true, true);
NewDef = Copies.back();
}
DOUT << "Adding an edge from SU # " << NewDef->NodeNum
<< " to SU #" << TrySU->NodeNum << "\n";
LiveRegDefs[Reg] = NewDef;
AddPred(NewDef, TrySU, true, true);
TrySU->isAvailable = false;
CurSU = NewDef;
}
if (!CurSU) {
assert(false && "Unable to resolve live physical register dependencies!");
abort();
}
}
// Add the nodes that aren't ready back onto the available list.
for (unsigned i = 0, e = NotReady.size(); i != e; ++i) {
NotReady[i]->isPending = false;
// May no longer be available due to backtracking.
if (NotReady[i]->isAvailable)
AvailableQueue->push(NotReady[i]);
}
NotReady.clear();
if (!CurSU)
Sequence.push_back(0);
else {
ScheduleNodeBottomUp(CurSU, CurCycle);
Sequence.push_back(CurSU);
}
++CurCycle;
}
// 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;
unsigned DeadNodes = 0;
unsigned Noops = 0;
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
if (!SUnits[i].isScheduled) {
if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
++DeadNodes;
continue;
}
if (!AnyNotSched)
cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
cerr << "has not been scheduled!\n";
AnyNotSched = true;
}
if (SUnits[i].NumSuccsLeft != 0) {
if (!AnyNotSched)
cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
cerr << "has successors left!\n";
AnyNotSched = true;
}
}
for (unsigned i = 0, e = Sequence.size(); i != e; ++i)
if (!Sequence[i])
++Noops;
assert(!AnyNotSched);
assert(Sequence.size() + DeadNodes - Noops == SUnits.size() &&
"The number of nodes scheduled doesn't match the expected number!");
#endif
}
//===----------------------------------------------------------------------===//
// Top-Down Scheduling
//===----------------------------------------------------------------------===//
/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to
/// the AvailableQueue if the count reaches zero. Also update its cycle bound.
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);
--SuccSU->NumPredsLeft;
#ifndef NDEBUG
if (SuccSU->NumPredsLeft < 0) {
cerr << "*** List scheduling failed! ***\n";
SuccSU->dump(&DAG);
cerr << " has been released too many times!\n";
assert(0);
}
#endif
if (SuccSU->NumPredsLeft == 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) {
DOUT << "*** Scheduling [" << CurCycle << "]: ";
DEBUG(SU->dump(&DAG));
SU->Cycle = CurCycle;
AvailableQueue->ScheduledNode(SU);
// Top down: release successors
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I)
ReleaseSucc(I->Dep, I->isCtrl, CurCycle);
SU->isScheduled = true;
}
/// ListScheduleTopDown - The main loop of list scheduling for top-down
/// schedulers.
void ScheduleDAGRRList::ListScheduleTopDown() {
unsigned CurCycle = 0;
// 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;
}
}
// 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()) {
SUnit *CurSU = AvailableQueue->pop();
while (CurSU && CurSU->CycleBound > CurCycle) {
NotReady.push_back(CurSU);
CurSU = AvailableQueue->pop();
}
// Add the nodes that aren't ready back onto the available list.
AvailableQueue->push_all(NotReady);
NotReady.clear();
if (!CurSU)
Sequence.push_back(0);
else {
ScheduleNodeTopDown(CurSU, CurCycle);
Sequence.push_back(CurSU);
}
++CurCycle;
}
#ifndef NDEBUG
// Verify that all SUnits were scheduled.
bool AnyNotSched = false;
unsigned DeadNodes = 0;
unsigned Noops = 0;
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
if (!SUnits[i].isScheduled) {
if (SUnits[i].NumPreds == 0 && SUnits[i].NumSuccs == 0) {
++DeadNodes;
continue;
}
if (!AnyNotSched)
cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
cerr << "has not been scheduled!\n";
AnyNotSched = true;
}
if (SUnits[i].NumPredsLeft != 0) {
if (!AnyNotSched)
cerr << "*** List scheduling failed! ***\n";
SUnits[i].dump(&DAG);
cerr << "has predecessors left!\n";
AnyNotSched = true;
}
}
for (unsigned i = 0, e = Sequence.size(); i != e; ++i)
if (!Sequence[i])
++Noops;
assert(!AnyNotSched);
assert(Sequence.size() + DeadNodes - Noops == SUnits.size() &&
"The number of nodes scheduled doesn't match the expected number!");
#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 bu_ls_rr_fast_sort : public std::binary_function<SUnit*, SUnit*, bool>{
RegReductionPriorityQueue<bu_ls_rr_fast_sort> *SPQ;
bu_ls_rr_fast_sort(RegReductionPriorityQueue<bu_ls_rr_fast_sort> *spq)
: SPQ(spq) {}
bu_ls_rr_fast_sort(const bu_ls_rr_fast_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
static inline bool isCopyFromLiveIn(const SUnit *SU) {
SDNode *N = SU->Node;
return N && N->getOpcode() == ISD::CopyFromReg &&
N->getOperand(N->getNumOperands()-1).getValueType() != MVT::Flag;
}
/// CalcNodeBUSethiUllmanNumber - Compute Sethi Ullman number for bottom up
/// scheduling. Smaller number is the higher priority.
static unsigned
CalcNodeBUSethiUllmanNumber(const SUnit *SU, std::vector<unsigned> &SUNumbers) {
unsigned &SethiUllmanNumber = SUNumbers[SU->NodeNum];
if (SethiUllmanNumber != 0)
return SethiUllmanNumber;
unsigned Extra = 0;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl) continue; // ignore chain preds
SUnit *PredSU = I->Dep;
unsigned PredSethiUllman = CalcNodeBUSethiUllmanNumber(PredSU, SUNumbers);
if (PredSethiUllman > SethiUllmanNumber) {
SethiUllmanNumber = PredSethiUllman;
Extra = 0;
} else if (PredSethiUllman == SethiUllmanNumber && !I->isCtrl)
++Extra;
}
SethiUllmanNumber += Extra;
if (SethiUllmanNumber == 0)
SethiUllmanNumber = 1;
return SethiUllmanNumber;
}
/// CalcNodeTDSethiUllmanNumber - Compute Sethi Ullman number for top down
/// scheduling. Smaller number is the higher priority.
static unsigned
CalcNodeTDSethiUllmanNumber(const SUnit *SU, std::vector<unsigned> &SUNumbers) {
unsigned &SethiUllmanNumber = SUNumbers[SU->NodeNum];
if (SethiUllmanNumber != 0)
return SethiUllmanNumber;
unsigned Opc = SU->Node ? SU->Node->getOpcode() : 0;
if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
SethiUllmanNumber = 0xffff;
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 = 0;
else if (SU->NumPredsLeft == 0 &&
(Opc != ISD::CopyFromReg || isCopyFromLiveIn(SU)))
SethiUllmanNumber = 0xffff;
else {
int Extra = 0;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl) continue; // ignore chain preds
SUnit *PredSU = I->Dep;
unsigned PredSethiUllman = CalcNodeTDSethiUllmanNumber(PredSU, SUNumbers);
if (PredSethiUllman > SethiUllmanNumber) {
SethiUllmanNumber = PredSethiUllman;
Extra = 0;
} else if (PredSethiUllman == SethiUllmanNumber && !I->isCtrl)
++Extra;
}
SethiUllmanNumber += Extra;
}
return SethiUllmanNumber;
}
namespace {
template<class SF>
class VISIBILITY_HIDDEN RegReductionPriorityQueue
: public SchedulingPriorityQueue {
PriorityQueue<SUnit*, std::vector<SUnit*>, SF> Queue;
unsigned currentQueueId;
public:
RegReductionPriorityQueue() :
Queue(SF(this)), currentQueueId(0) {}
virtual void initNodes(std::vector<SUnit> &sunits) = 0;
virtual void addNode(const SUnit *SU) = 0;
virtual void updateNode(const SUnit *SU) = 0;
virtual void releaseState() = 0;
virtual unsigned getNodePriority(const SUnit *SU) const = 0;
unsigned size() const { return Queue.size(); }
bool empty() const { return Queue.empty(); }
void push(SUnit *U) {
assert(!U->NodeQueueId && "Node in the queue already");
U->NodeQueueId = ++currentQueueId;
Queue.push(U);
}
void push_all(const std::vector<SUnit *> &Nodes) {
for (unsigned i = 0, e = Nodes.size(); i != e; ++i)
push(Nodes[i]);
}
SUnit *pop() {
if (empty()) return NULL;
SUnit *V = Queue.top();
Queue.pop();
V->NodeQueueId = 0;
return V;
}
void remove(SUnit *SU) {
assert(!Queue.empty() && "Queue is empty!");
assert(SU->NodeQueueId != 0 && "Not in queue!");
Queue.erase_one(SU);
SU->NodeQueueId = 0;
}
};
class VISIBILITY_HIDDEN BURegReductionPriorityQueue
: public RegReductionPriorityQueue<bu_ls_rr_sort> {
// SUnits - The SUnits for the current graph.
std::vector<SUnit> *SUnits;
// SethiUllmanNumbers - The SethiUllman number for each node.
std::vector<unsigned> SethiUllmanNumbers;
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
ScheduleDAGRRList *scheduleDAG;
public:
explicit BURegReductionPriorityQueue(const TargetInstrInfo *tii,
const TargetRegisterInfo *tri)
: TII(tii), TRI(tri), scheduleDAG(NULL) {}
void initNodes(std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Add pseudo dependency edges for two-address nodes.
AddPseudoTwoAddrDeps();
// Calculate node priorities.
CalculateSethiUllmanNumbers();
}
void addNode(const SUnit *SU) {
unsigned SUSize = SethiUllmanNumbers.size();
if (SUnits->size() > SUSize)
SethiUllmanNumbers.resize(SUSize*2, 0);
CalcNodeBUSethiUllmanNumber(SU, SethiUllmanNumbers);
}
void updateNode(const SUnit *SU) {
SethiUllmanNumbers[SU->NodeNum] = 0;
CalcNodeBUSethiUllmanNumber(SU, SethiUllmanNumbers);
}
void releaseState() {
SUnits = 0;
SethiUllmanNumbers.clear();
}
unsigned getNodePriority(const SUnit *SU) const {
assert(SU->NodeNum < SethiUllmanNumbers.size());
unsigned Opc = SU->Node ? SU->Node->getOpcode() : 0;
if (Opc == ISD::CopyFromReg && !isCopyFromLiveIn(SU))
// CopyFromReg should be close to its def because it restricts
// allocation choices. But if it is a livein then perhaps we want it
// closer to its uses so it can be coalesced.
return 0xffff;
else if (Opc == ISD::TokenFactor || Opc == ISD::CopyToReg)
// CopyToReg should be close to its uses to facilitate coalescing and
// avoid spilling.
return 0;
else if (Opc == TargetInstrInfo::EXTRACT_SUBREG ||
Opc == TargetInstrInfo::INSERT_SUBREG)
// EXTRACT_SUBREG / INSERT_SUBREG should be close to its use to
// facilitate coalescing.
return 0;
else if (SU->NumSuccs == 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 large SethiUllman number so it will be scheduled right
// before its predecessors that it doesn't lengthen their live ranges.
return 0xffff;
else if (SU->NumPreds == 0)
// If SU does not have a def, schedule it close to its uses because it
// does not lengthen any live ranges.
return 0;
else
return SethiUllmanNumbers[SU->NodeNum];
}
void setScheduleDAG(ScheduleDAGRRList *scheduleDag) {
scheduleDAG = scheduleDag;
}
private:
bool canClobber(const SUnit *SU, const SUnit *Op);
void AddPseudoTwoAddrDeps();
void CalculateSethiUllmanNumbers();
};
class VISIBILITY_HIDDEN BURegReductionFastPriorityQueue
: public RegReductionPriorityQueue<bu_ls_rr_fast_sort> {
// SUnits - The SUnits for the current graph.
const std::vector<SUnit> *SUnits;
// SethiUllmanNumbers - The SethiUllman number for each node.
std::vector<unsigned> SethiUllmanNumbers;
public:
explicit BURegReductionFastPriorityQueue() {}
void initNodes(std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Calculate node priorities.
CalculateSethiUllmanNumbers();
}
void addNode(const SUnit *SU) {
unsigned SUSize = SethiUllmanNumbers.size();
if (SUnits->size() > SUSize)
SethiUllmanNumbers.resize(SUSize*2, 0);
CalcNodeBUSethiUllmanNumber(SU, SethiUllmanNumbers);
}
void updateNode(const SUnit *SU) {
SethiUllmanNumbers[SU->NodeNum] = 0;
CalcNodeBUSethiUllmanNumber(SU, SethiUllmanNumbers);
}
void releaseState() {
SUnits = 0;
SethiUllmanNumbers.clear();
}
unsigned getNodePriority(const SUnit *SU) const {
return SethiUllmanNumbers[SU->NodeNum];
}
private:
void CalculateSethiUllmanNumbers();
};
class VISIBILITY_HIDDEN TDRegReductionPriorityQueue
: public RegReductionPriorityQueue<td_ls_rr_sort> {
// SUnits - The SUnits for the current graph.
const std::vector<SUnit> *SUnits;
// SethiUllmanNumbers - The SethiUllman number for each node.
std::vector<unsigned> SethiUllmanNumbers;
public:
TDRegReductionPriorityQueue() {}
void initNodes(std::vector<SUnit> &sunits) {
SUnits = &sunits;
// Calculate node priorities.
CalculateSethiUllmanNumbers();
}
void addNode(const SUnit *SU) {
unsigned SUSize = SethiUllmanNumbers.size();
if (SUnits->size() > SUSize)
SethiUllmanNumbers.resize(SUSize*2, 0);
CalcNodeTDSethiUllmanNumber(SU, SethiUllmanNumbers);
}
void updateNode(const SUnit *SU) {
SethiUllmanNumbers[SU->NodeNum] = 0;
CalcNodeTDSethiUllmanNumber(SU, SethiUllmanNumbers);
}
void releaseState() {
SUnits = 0;
SethiUllmanNumbers.clear();
}
unsigned getNodePriority(const SUnit *SU) const {
assert(SU->NodeNum < SethiUllmanNumbers.size());
return SethiUllmanNumbers[SU->NodeNum];
}
private:
void CalculateSethiUllmanNumbers();
};
}
/// closestSucc - Returns the scheduled cycle of the successor which is
/// closet to the current cycle.
static unsigned closestSucc(const SUnit *SU) {
unsigned MaxCycle = 0;
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
unsigned Cycle = I->Dep->Cycle;
// If there are bunch of CopyToRegs stacked up, they should be considered
// to be at the same position.
if (I->Dep->Node && I->Dep->Node->getOpcode() == ISD::CopyToReg)
Cycle = closestSucc(I->Dep)+1;
if (Cycle > MaxCycle)
MaxCycle = Cycle;
}
return MaxCycle;
}
/// calcMaxScratches - Returns an cost estimate of the worse case requirement
/// for scratch registers. Live-in operands and live-out results don't count
/// since they are "fixed".
static unsigned calcMaxScratches(const SUnit *SU) {
unsigned Scratches = 0;
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl) continue; // ignore chain preds
if (!I->Dep->Node || I->Dep->Node->getOpcode() != ISD::CopyFromReg)
Scratches++;
}
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->isCtrl) continue; // ignore chain succs
if (!I->Dep->Node || I->Dep->Node->getOpcode() != ISD::CopyToReg)
Scratches += 10;
}
return Scratches;
}
// Bottom up
bool bu_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
unsigned LPriority = SPQ->getNodePriority(left);
unsigned RPriority = SPQ->getNodePriority(right);
if (LPriority != RPriority)
return LPriority > RPriority;
// Try schedule def + use closer when Sethi-Ullman numbers are the same.
// e.g.
// t1 = op t2, c1
// t3 = op t4, c2
//
// and the following instructions are both ready.
// t2 = op c3
// t4 = op c4
//
// Then schedule t2 = op first.
// i.e.
// t4 = op c4
// t2 = op c3
// t1 = op t2, c1
// t3 = op t4, c2
//
// This creates more short live intervals.
unsigned LDist = closestSucc(left);
unsigned RDist = closestSucc(right);
if (LDist != RDist)
return LDist < RDist;
// Intuitively, it's good to push down instructions whose results are
// liveout so their long live ranges won't conflict with other values
// which are needed inside the BB. Further prioritize liveout instructions
// by the number of operands which are calculated within the BB.
unsigned LScratch = calcMaxScratches(left);
unsigned RScratch = calcMaxScratches(right);
if (LScratch != RScratch)
return LScratch > RScratch;
if (left->Height != right->Height)
return left->Height > right->Height;
if (left->Depth != right->Depth)
return left->Depth < right->Depth;
if (left->CycleBound != right->CycleBound)
return left->CycleBound > right->CycleBound;
assert(left->NodeQueueId && right->NodeQueueId &&
"NodeQueueId cannot be zero");
return (left->NodeQueueId > right->NodeQueueId);
}
bool
bu_ls_rr_fast_sort::operator()(const SUnit *left, const SUnit *right) const {
unsigned LPriority = SPQ->getNodePriority(left);
unsigned RPriority = SPQ->getNodePriority(right);
if (LPriority != RPriority)
return LPriority > RPriority;
assert(left->NodeQueueId && right->NodeQueueId &&
"NodeQueueId cannot be zero");
return (left->NodeQueueId > right->NodeQueueId);
}
bool
BURegReductionPriorityQueue::canClobber(const SUnit *SU, const SUnit *Op) {
if (SU->isTwoAddress) {
unsigned Opc = SU->Node->getMachineOpcode();
const TargetInstrDesc &TID = TII->get(Opc);
unsigned NumRes = TID.getNumDefs();
unsigned NumOps = TID.getNumOperands() - NumRes;
for (unsigned i = 0; i != NumOps; ++i) {
if (TID.getOperandConstraint(i+NumRes, TOI::TIED_TO) != -1) {
SDNode *DU = SU->Node->getOperand(i).getNode();
if (DU->getNodeId() != -1 &&
Op->OrigNode == &(*SUnits)[DU->getNodeId()])
return true;
}
}
}
return false;
}
/// hasCopyToRegUse - Return true if SU has a value successor that is a
/// CopyToReg node.
static bool hasCopyToRegUse(const SUnit *SU) {
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
if (I->isCtrl) continue;
const SUnit *SuccSU = I->Dep;
if (SuccSU->Node && SuccSU->Node->getOpcode() == ISD::CopyToReg)
return true;
}
return false;
}
/// canClobberPhysRegDefs - True if SU would clobber one of SuccSU's
/// physical register defs.
static bool canClobberPhysRegDefs(const SUnit *SuccSU, const SUnit *SU,
const TargetInstrInfo *TII,
const TargetRegisterInfo *TRI) {
SDNode *N = SuccSU->Node;
unsigned NumDefs = TII->get(N->getMachineOpcode()).getNumDefs();
const unsigned *ImpDefs = TII->get(N->getMachineOpcode()).getImplicitDefs();
assert(ImpDefs && "Caller should check hasPhysRegDefs");
const unsigned *SUImpDefs =
TII->get(SU->Node->getMachineOpcode()).getImplicitDefs();
if (!SUImpDefs)
return false;
for (unsigned i = NumDefs, e = N->getNumValues(); i != e; ++i) {
MVT VT = N->getValueType(i);
if (VT == MVT::Flag || VT == MVT::Other)
continue;
if (!N->hasAnyUseOfValue(i))
continue;
unsigned Reg = ImpDefs[i - NumDefs];
for (;*SUImpDefs; ++SUImpDefs) {
unsigned SUReg = *SUImpDefs;
if (TRI->regsOverlap(Reg, SUReg))
return true;
}
}
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). If both nodes are two-address, favor the
/// one that has a CopyToReg use (more likely to be a loop induction update).
/// If both are two-address, but one is commutable while the other is not
/// commutable, favor the one that's not commutable.
void BURegReductionPriorityQueue::AddPseudoTwoAddrDeps() {
for (unsigned i = 0, e = SUnits->size(); i != e; ++i) {
SUnit *SU = &(*SUnits)[i];
if (!SU->isTwoAddress)
continue;
SDNode *Node = SU->Node;
if (!Node || !Node->isMachineOpcode() || SU->FlaggedNodes.size() > 0)
continue;
unsigned Opc = Node->getMachineOpcode();
const TargetInstrDesc &TID = TII->get(Opc);
unsigned NumRes = TID.getNumDefs();
unsigned NumOps = TID.getNumOperands() - NumRes;
for (unsigned j = 0; j != NumOps; ++j) {
if (TID.getOperandConstraint(j+NumRes, TOI::TIED_TO) != -1) {
SDNode *DU = SU->Node->getOperand(j).getNode();
if (DU->getNodeId() == -1)
continue;
const SUnit *DUSU = &(*SUnits)[DU->getNodeId()];
if (!DUSU) continue;
for (SUnit::const_succ_iterator I = DUSU->Succs.begin(),
E = DUSU->Succs.end(); I != E; ++I) {
if (I->isCtrl) continue;
SUnit *SuccSU = I->Dep;
if (SuccSU == SU)
continue;
// Be conservative. Ignore if nodes aren't at roughly the same
// depth and height.
if (SuccSU->Height < SU->Height && (SU->Height - SuccSU->Height) > 1)
continue;
if (!SuccSU->Node || !SuccSU->Node->isMachineOpcode())
continue;
// Don't constrain nodes with physical register defs if the
// predecessor can clobber them.
if (SuccSU->hasPhysRegDefs) {
if (canClobberPhysRegDefs(SuccSU, SU, TII, TRI))
continue;
}
// Don't constraint extract_subreg / insert_subreg these may be
// coalesced away. We don't them close to their uses.
unsigned SuccOpc = SuccSU->Node->getMachineOpcode();
if (SuccOpc == TargetInstrInfo::EXTRACT_SUBREG ||
SuccOpc == TargetInstrInfo::INSERT_SUBREG)
continue;
if ((!canClobber(SuccSU, DUSU) ||
(hasCopyToRegUse(SU) && !hasCopyToRegUse(SuccSU)) ||
(!SU->isCommutable && SuccSU->isCommutable)) &&
!scheduleDAG->IsReachable(SuccSU, SU)) {
DOUT << "Adding an edge from SU # " << SU->NodeNum
<< " to SU #" << SuccSU->NodeNum << "\n";
scheduleDAG->AddPred(SU, SuccSU, true, true);
}
}
}
}
}
}
/// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
/// scheduling units.
void BURegReductionPriorityQueue::CalculateSethiUllmanNumbers() {
SethiUllmanNumbers.assign(SUnits->size(), 0);
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
CalcNodeBUSethiUllmanNumber(&(*SUnits)[i], SethiUllmanNumbers);
}
void BURegReductionFastPriorityQueue::CalculateSethiUllmanNumbers() {
SethiUllmanNumbers.assign(SUnits->size(), 0);
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
CalcNodeBUSethiUllmanNumber(&(*SUnits)[i], SethiUllmanNumbers);
}
/// LimitedSumOfUnscheduledPredsOfSuccs - Compute the sum of the unscheduled
/// predecessors of the successors of the SUnit SU. Stop when the provided
/// limit is exceeded.
static unsigned LimitedSumOfUnscheduledPredsOfSuccs(const SUnit *SU,
unsigned Limit) {
unsigned Sum = 0;
for (SUnit::const_succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I) {
const SUnit *SuccSU = I->Dep;
for (SUnit::const_pred_iterator II = SuccSU->Preds.begin(),
EE = SuccSU->Preds.end(); II != EE; ++II) {
SUnit *PredSU = II->Dep;
if (!PredSU->isScheduled)
if (++Sum > Limit)
return Sum;
}
}
return Sum;
}
// Top down
bool td_ls_rr_sort::operator()(const SUnit *left, const SUnit *right) const {
unsigned LPriority = SPQ->getNodePriority(left);
unsigned RPriority = SPQ->getNodePriority(right);
bool LIsTarget = left->Node && left->Node->isMachineOpcode();
bool RIsTarget = right->Node && right->Node->isMachineOpcode();
bool LIsFloater = LIsTarget && left->NumPreds == 0;
bool RIsFloater = RIsTarget && right->NumPreds == 0;
unsigned LBonus = (LimitedSumOfUnscheduledPredsOfSuccs(left,1) == 1) ? 2 : 0;
unsigned RBonus = (LimitedSumOfUnscheduledPredsOfSuccs(right,1) == 1) ? 2 : 0;
if (left->NumSuccs == 0 && right->NumSuccs != 0)
return false;
else if (left->NumSuccs != 0 && right->NumSuccs == 0)
return true;
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 LPriority+LBonus < RPriority+RBonus;
if (left->Depth != right->Depth)
return left->Depth < right->Depth;
if (left->NumSuccsLeft != right->NumSuccsLeft)
return left->NumSuccsLeft > right->NumSuccsLeft;
if (left->CycleBound != right->CycleBound)
return left->CycleBound > right->CycleBound;
assert(left->NodeQueueId && right->NodeQueueId &&
"NodeQueueId cannot be zero");
return (left->NodeQueueId > right->NodeQueueId);
}
/// CalculateSethiUllmanNumbers - Calculate Sethi-Ullman numbers of all
/// scheduling units.
void TDRegReductionPriorityQueue::CalculateSethiUllmanNumbers() {
SethiUllmanNumbers.assign(SUnits->size(), 0);
for (unsigned i = 0, e = SUnits->size(); i != e; ++i)
CalcNodeTDSethiUllmanNumber(&(*SUnits)[i], SethiUllmanNumbers);
}
//===----------------------------------------------------------------------===//
// Public Constructor Functions
//===----------------------------------------------------------------------===//
llvm::ScheduleDAG* llvm::createBURRListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
const TargetMachine *TM,
MachineBasicBlock *BB,
bool Fast) {
if (Fast)
return new ScheduleDAGRRList(*DAG, BB, *TM, true, true,
new BURegReductionFastPriorityQueue());
const TargetInstrInfo *TII = TM->getInstrInfo();
const TargetRegisterInfo *TRI = TM->getRegisterInfo();
BURegReductionPriorityQueue *PQ = new BURegReductionPriorityQueue(TII, TRI);
ScheduleDAGRRList *SD =
new ScheduleDAGRRList(*DAG, BB, *TM, true, false, PQ);
PQ->setScheduleDAG(SD);
return SD;
}
llvm::ScheduleDAG* llvm::createTDRRListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
const TargetMachine *TM,
MachineBasicBlock *BB,
bool Fast) {
return new ScheduleDAGRRList(*DAG, BB, *TM, false, Fast,
new TDRegReductionPriorityQueue());
}
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