llvm-6502/include/llvm/CodeGen/ScheduleDAG.h
Evan Cheng f10c973797 If a node that defines a physical register that is expensive to copy. The
scheduler will try a number of tricks in order to avoid generating the
copies. This may not be possible in case the node produces a chain value
that prevent movement. Try unfolding the load from the node before to allow
it to be moved / cloned.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42625 91177308-0d34-0410-b5e6-96231b3b80d8
2007-10-05 01:39:18 +00:00

449 lines
17 KiB
C++

//===------- llvm/CodeGen/ScheduleDAG.h - Common Base Class------*- C++ -*-===//
//
// 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 file implements the ScheduleDAG class, which is used as the common
// base class for SelectionDAG-based instruction scheduler.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_SCHEDULEDAG_H
#define LLVM_CODEGEN_SCHEDULEDAG_H
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/SmallSet.h"
namespace llvm {
struct InstrStage;
struct SUnit;
class MachineConstantPool;
class MachineModuleInfo;
class MachineInstr;
class MRegisterInfo;
class SelectionDAG;
class SelectionDAGISel;
class SSARegMap;
class TargetInstrInfo;
class TargetInstrDescriptor;
class TargetMachine;
class TargetRegisterClass;
/// HazardRecognizer - This determines whether or not an instruction can be
/// issued this cycle, and whether or not a noop needs to be inserted to handle
/// the hazard.
class HazardRecognizer {
public:
virtual ~HazardRecognizer();
enum HazardType {
NoHazard, // This instruction can be emitted at this cycle.
Hazard, // This instruction can't be emitted at this cycle.
NoopHazard // This instruction can't be emitted, and needs noops.
};
/// getHazardType - Return the hazard type of emitting this node. There are
/// three possible results. Either:
/// * NoHazard: it is legal to issue this instruction on this cycle.
/// * Hazard: issuing this instruction would stall the machine. If some
/// other instruction is available, issue it first.
/// * NoopHazard: issuing this instruction would break the program. If
/// some other instruction can be issued, do so, otherwise issue a noop.
virtual HazardType getHazardType(SDNode *Node) {
return NoHazard;
}
/// EmitInstruction - This callback is invoked when an instruction is
/// emitted, to advance the hazard state.
virtual void EmitInstruction(SDNode *Node) {
}
/// AdvanceCycle - This callback is invoked when no instructions can be
/// issued on this cycle without a hazard. This should increment the
/// internal state of the hazard recognizer so that previously "Hazard"
/// instructions will now not be hazards.
virtual void AdvanceCycle() {
}
/// EmitNoop - This callback is invoked when a noop was added to the
/// instruction stream.
virtual void EmitNoop() {
}
};
/// SDep - Scheduling dependency. It keeps track of dependent nodes,
/// cost of the depdenency, etc.
struct SDep {
SUnit *Dep; // Dependent - either a predecessor or a successor.
unsigned Reg; // If non-zero, this dep is a phy register dependency.
int Cost; // Cost of the dependency.
bool isCtrl : 1; // True iff it's a control dependency.
bool isSpecial : 1; // True iff it's a special ctrl dep added during sched.
SDep(SUnit *d, unsigned r, int t, bool c, bool s)
: Dep(d), Reg(r), Cost(t), isCtrl(c), isSpecial(s) {}
};
/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
/// a group of nodes flagged together.
struct SUnit {
SDNode *Node; // Representative node.
SmallVector<SDNode*,4> FlaggedNodes;// All nodes flagged to Node.
unsigned InstanceNo; // Instance#. One SDNode can be multiple
// SUnit due to cloning.
// Preds/Succs - The SUnits before/after us in the graph. The boolean value
// is true if the edge is a token chain edge, false if it is a value edge.
SmallVector<SDep, 4> Preds; // All sunit predecessors.
SmallVector<SDep, 4> Succs; // All sunit successors.
typedef SmallVector<SDep, 4>::iterator pred_iterator;
typedef SmallVector<SDep, 4>::iterator succ_iterator;
typedef SmallVector<SDep, 4>::const_iterator const_pred_iterator;
typedef SmallVector<SDep, 4>::const_iterator const_succ_iterator;
unsigned NodeNum; // Entry # of node in the node vector.
unsigned short Latency; // Node latency.
short NumPreds; // # of preds.
short NumSuccs; // # of sucss.
short NumPredsLeft; // # of preds not scheduled.
short NumSuccsLeft; // # of succs not scheduled.
bool isTwoAddress : 1; // Is a two-address instruction.
bool isCommutable : 1; // Is a commutable instruction.
bool hasPhysRegDefs : 1; // Has physreg defs that are being used.
bool isPending : 1; // True once pending.
bool isAvailable : 1; // True once available.
bool isScheduled : 1; // True once scheduled.
unsigned CycleBound; // Upper/lower cycle to be scheduled at.
unsigned Cycle; // Once scheduled, the cycle of the op.
unsigned Depth; // Node depth;
unsigned Height; // Node height;
const TargetRegisterClass *CopyDstRC; // Is a special copy node if not null.
const TargetRegisterClass *CopySrcRC;
SUnit(SDNode *node, unsigned nodenum)
: Node(node), InstanceNo(0), NodeNum(nodenum), Latency(0),
NumPreds(0), NumSuccs(0), NumPredsLeft(0), NumSuccsLeft(0),
isTwoAddress(false), isCommutable(false), hasPhysRegDefs(false),
isPending(false), isAvailable(false), isScheduled(false),
CycleBound(0), Cycle(0), Depth(0), Height(0),
CopyDstRC(NULL), CopySrcRC(NULL) {}
/// addPred - This adds the specified node as a pred of the current node if
/// not already. This returns true if this is a new pred.
bool addPred(SUnit *N, bool isCtrl, bool isSpecial,
unsigned PhyReg = 0, int Cost = 1) {
for (unsigned i = 0, e = Preds.size(); i != e; ++i)
if (Preds[i].Dep == N &&
Preds[i].isCtrl == isCtrl && Preds[i].isSpecial == isSpecial)
return false;
Preds.push_back(SDep(N, PhyReg, Cost, isCtrl, isSpecial));
N->Succs.push_back(SDep(this, PhyReg, Cost, isCtrl, isSpecial));
if (!isCtrl) {
++NumPreds;
++N->NumSuccs;
}
if (!N->isScheduled)
++NumPredsLeft;
if (!isScheduled)
++N->NumSuccsLeft;
return true;
}
bool removePred(SUnit *N, bool isCtrl, bool isSpecial) {
for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
I != E; ++I)
if (I->Dep == N && I->isCtrl == isCtrl && I->isSpecial == isSpecial) {
bool FoundSucc = false;
for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(),
EE = N->Succs.end(); II != EE; ++II)
if (II->Dep == this &&
II->isCtrl == isCtrl && II->isSpecial == isSpecial) {
FoundSucc = true;
N->Succs.erase(II);
break;
}
assert(FoundSucc && "Mismatching preds / succs lists!");
Preds.erase(I);
if (!isCtrl) {
--NumPreds;
--N->NumSuccs;
}
if (!N->isScheduled)
--NumPredsLeft;
if (!isScheduled)
--N->NumSuccsLeft;
return true;
}
return false;
}
bool isPred(SUnit *N) {
for (unsigned i = 0, e = Preds.size(); i != e; ++i)
if (Preds[i].Dep == N)
return true;
return false;
}
bool isSucc(SUnit *N) {
for (unsigned i = 0, e = Succs.size(); i != e; ++i)
if (Succs[i].Dep == N)
return true;
return false;
}
void dump(const SelectionDAG *G) const;
void dumpAll(const SelectionDAG *G) const;
};
//===--------------------------------------------------------------------===//
/// SchedulingPriorityQueue - This interface is used to plug different
/// priorities computation algorithms into the list scheduler. It implements
/// the interface of a standard priority queue, where nodes are inserted in
/// arbitrary order and returned in priority order. The computation of the
/// priority and the representation of the queue are totally up to the
/// implementation to decide.
///
class SchedulingPriorityQueue {
public:
virtual ~SchedulingPriorityQueue() {}
virtual void initNodes(DenseMap<SDNode*, std::vector<SUnit*> > &SUMap,
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 size() const = 0;
virtual bool empty() const = 0;
virtual void push(SUnit *U) = 0;
virtual void push_all(const std::vector<SUnit *> &Nodes) = 0;
virtual SUnit *pop() = 0;
virtual void remove(SUnit *SU) = 0;
/// ScheduledNode - As each node is scheduled, this method is invoked. This
/// allows the priority function to adjust the priority of node that have
/// already been emitted.
virtual void ScheduledNode(SUnit *Node) {}
virtual void UnscheduledNode(SUnit *Node) {}
};
class ScheduleDAG {
public:
SelectionDAG &DAG; // DAG of the current basic block
MachineBasicBlock *BB; // Current basic block
const TargetMachine &TM; // Target processor
const TargetInstrInfo *TII; // Target instruction information
const MRegisterInfo *MRI; // Target processor register info
SSARegMap *RegMap; // Virtual/real register map
MachineConstantPool *ConstPool; // Target constant pool
std::vector<SUnit*> Sequence; // The schedule. Null SUnit*'s
// represent noop instructions.
DenseMap<SDNode*, std::vector<SUnit*> > SUnitMap;
// SDNode to SUnit mapping (n -> n).
std::vector<SUnit> SUnits; // The scheduling units.
SmallSet<SDNode*, 16> CommuteSet; // Nodes the should be commuted.
ScheduleDAG(SelectionDAG &dag, MachineBasicBlock *bb,
const TargetMachine &tm)
: DAG(dag), BB(bb), TM(tm) {}
virtual ~ScheduleDAG() {}
/// viewGraph - Pop up a GraphViz/gv window with the ScheduleDAG rendered
/// using 'dot'.
///
void viewGraph();
/// Run - perform scheduling.
///
MachineBasicBlock *Run();
/// isPassiveNode - Return true if the node is a non-scheduled leaf.
///
static bool isPassiveNode(SDNode *Node) {
if (isa<ConstantSDNode>(Node)) return true;
if (isa<RegisterSDNode>(Node)) return true;
if (isa<GlobalAddressSDNode>(Node)) return true;
if (isa<BasicBlockSDNode>(Node)) return true;
if (isa<FrameIndexSDNode>(Node)) return true;
if (isa<ConstantPoolSDNode>(Node)) return true;
if (isa<JumpTableSDNode>(Node)) return true;
if (isa<ExternalSymbolSDNode>(Node)) return true;
return false;
}
/// NewSUnit - Creates a new SUnit and return a ptr to it.
///
SUnit *NewSUnit(SDNode *N) {
SUnits.push_back(SUnit(N, SUnits.size()));
return &SUnits.back();
}
/// Clone - Creates a clone of the specified SUnit. It does not copy the
/// predecessors / successors info nor the temporary scheduling states.
SUnit *Clone(SUnit *N);
/// BuildSchedUnits - Build SUnits from the selection dag that we are input.
/// This SUnit graph is similar to the SelectionDAG, but represents flagged
/// together nodes with a single SUnit.
void BuildSchedUnits();
/// ComputeLatency - Compute node latency.
///
void ComputeLatency(SUnit *SU);
/// CalculateDepths, CalculateHeights - Calculate node depth / height.
///
void CalculateDepths();
void CalculateHeights();
/// CountResults - The results of target nodes have register or immediate
/// operands first, then an optional chain, and optional flag operands
/// (which do not go into the machine instrs.)
static unsigned CountResults(SDNode *Node);
/// CountOperands The inputs to target nodes have any actual inputs first,
/// followed by an optional chain operand, then flag operands. Compute the
/// number of actual operands that will go into the machine instr.
static unsigned CountOperands(SDNode *Node);
/// EmitNode - Generate machine code for an node and needed dependencies.
/// VRBaseMap contains, for each already emitted node, the first virtual
/// register number for the results of the node.
///
void EmitNode(SDNode *Node, unsigned InstNo,
DenseMap<SDOperand, unsigned> &VRBaseMap);
/// EmitNoop - Emit a noop instruction.
///
void EmitNoop();
void EmitCrossRCCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap);
/// EmitCopyFromReg - Generate machine code for an CopyFromReg node or an
/// implicit physical register output.
void EmitCopyFromReg(SDNode *Node, unsigned ResNo, unsigned InstNo,
unsigned SrcReg,
DenseMap<SDOperand, unsigned> &VRBaseMap);
void CreateVirtualRegisters(SDNode *Node, MachineInstr *MI,
const TargetInstrDescriptor &II,
DenseMap<SDOperand, unsigned> &VRBaseMap);
void EmitSchedule();
void dumpSchedule() const;
/// Schedule - Order nodes according to selected style.
///
virtual void Schedule() {}
private:
/// EmitSubregNode - Generate machine code for subreg nodes.
///
void EmitSubregNode(SDNode *Node,
DenseMap<SDOperand, unsigned> &VRBaseMap);
void AddOperand(MachineInstr *MI, SDOperand Op, unsigned IIOpNum,
const TargetInstrDescriptor *II,
DenseMap<SDOperand, unsigned> &VRBaseMap);
};
/// createBURRListDAGScheduler - This creates a bottom up register usage
/// reduction list scheduler.
ScheduleDAG* createBURRListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB);
/// createTDRRListDAGScheduler - This creates a top down register usage
/// reduction list scheduler.
ScheduleDAG* createTDRRListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB);
/// createTDListDAGScheduler - This creates a top-down list scheduler with
/// a hazard recognizer.
ScheduleDAG* createTDListDAGScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB);
/// createDefaultScheduler - This creates an instruction scheduler appropriate
/// for the target.
ScheduleDAG* createDefaultScheduler(SelectionDAGISel *IS,
SelectionDAG *DAG,
MachineBasicBlock *BB);
class SUnitIterator : public forward_iterator<SUnit, ptrdiff_t> {
SUnit *Node;
unsigned Operand;
SUnitIterator(SUnit *N, unsigned Op) : Node(N), Operand(Op) {}
public:
bool operator==(const SUnitIterator& x) const {
return Operand == x.Operand;
}
bool operator!=(const SUnitIterator& x) const { return !operator==(x); }
const SUnitIterator &operator=(const SUnitIterator &I) {
assert(I.Node == Node && "Cannot assign iterators to two different nodes!");
Operand = I.Operand;
return *this;
}
pointer operator*() const {
return Node->Preds[Operand].Dep;
}
pointer operator->() const { return operator*(); }
SUnitIterator& operator++() { // Preincrement
++Operand;
return *this;
}
SUnitIterator operator++(int) { // Postincrement
SUnitIterator tmp = *this; ++*this; return tmp;
}
static SUnitIterator begin(SUnit *N) { return SUnitIterator(N, 0); }
static SUnitIterator end (SUnit *N) {
return SUnitIterator(N, N->Preds.size());
}
unsigned getOperand() const { return Operand; }
const SUnit *getNode() const { return Node; }
bool isCtrlDep() const { return Node->Preds[Operand].isCtrl; }
};
template <> struct GraphTraits<SUnit*> {
typedef SUnit NodeType;
typedef SUnitIterator ChildIteratorType;
static inline NodeType *getEntryNode(SUnit *N) { return N; }
static inline ChildIteratorType child_begin(NodeType *N) {
return SUnitIterator::begin(N);
}
static inline ChildIteratorType child_end(NodeType *N) {
return SUnitIterator::end(N);
}
};
template <> struct GraphTraits<ScheduleDAG*> : public GraphTraits<SUnit*> {
typedef std::vector<SUnit>::iterator nodes_iterator;
static nodes_iterator nodes_begin(ScheduleDAG *G) {
return G->SUnits.begin();
}
static nodes_iterator nodes_end(ScheduleDAG *G) {
return G->SUnits.end();
}
};
}
#endif