1 //===------- llvm/CodeGen/ScheduleDAG.h - Common Base Class------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ScheduleDAG class, which is used as the common
11 // base class for instruction schedulers.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_SCHEDULEDAG_H
16 #define LLVM_CODEGEN_SCHEDULEDAG_H
18 #include "llvm/CodeGen/MachineBasicBlock.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/BitVector.h"
21 #include "llvm/ADT/GraphTraits.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/PointerIntPair.h"
27 class MachineConstantPool;
28 class MachineFunction;
29 class MachineModuleInfo;
30 class MachineRegisterInfo;
32 class TargetRegisterInfo;
36 class TargetInstrInfo;
37 class TargetInstrDesc;
40 class TargetRegisterClass;
41 template<class Graph> class GraphWriter;
43 /// SDep - Scheduling dependency. This represents one direction of an
44 /// edge in the scheduling DAG.
47 /// Kind - These are the different kinds of scheduling dependencies.
49 Data, ///< Regular data dependence (aka true-dependence).
50 Anti, ///< A register anti-dependedence (aka WAR).
51 Output, ///< A register output-dependence (aka WAW).
52 Order ///< Any other ordering dependency.
56 /// Dep - A pointer to the depending/depended-on SUnit, and an enum
57 /// indicating the kind of the dependency.
58 PointerIntPair<SUnit *, 2, Kind> Dep;
60 /// Contents - A union discriminated by the dependence kind.
62 /// Reg - For Data, Anti, and Output dependencies, the associated
63 /// register. For Data dependencies that don't currently have a register
64 /// assigned, this is set to zero.
67 /// Order - Additional information about Order dependencies.
69 /// isNormalMemory - True if both sides of the dependence
70 /// access memory in non-volatile and fully modeled ways.
71 bool isNormalMemory : 1;
73 /// isMustAlias - True if both sides of the dependence are known to
74 /// access the same memory.
77 /// isArtificial - True if this is an artificial dependency, meaning
78 /// it is not necessary for program correctness, and may be safely
79 /// deleted if necessary.
80 bool isArtificial : 1;
84 /// Latency - The time associated with this edge. Often this is just
85 /// the value of the Latency field of the predecessor, however advanced
86 /// models may provide additional information about specific edges.
90 /// SDep - Construct a null SDep. This is only for use by container
91 /// classes which require default constructors. SUnits may not
92 /// have null SDep edges.
93 SDep() : Dep(0, Data) {}
95 /// SDep - Construct an SDep with the specified values.
96 SDep(SUnit *S, Kind kind, unsigned latency = 1, unsigned Reg = 0,
97 bool isNormalMemory = false, bool isMustAlias = false,
98 bool isArtificial = false)
99 : Dep(S, kind), Contents(), Latency(latency) {
104 "SDep::Anti and SDep::Output must use a non-zero Reg!");
107 assert(!isMustAlias && "isMustAlias only applies with SDep::Order!");
108 assert(!isArtificial && "isArtificial only applies with SDep::Order!");
112 assert(Reg == 0 && "Reg given for non-register dependence!");
113 Contents.Order.isNormalMemory = isNormalMemory;
114 Contents.Order.isMustAlias = isMustAlias;
115 Contents.Order.isArtificial = isArtificial;
120 bool operator==(const SDep &Other) const {
121 if (Dep != Other.Dep || Latency != Other.Latency) return false;
122 switch (Dep.getInt()) {
126 return Contents.Reg == Other.Contents.Reg;
128 return Contents.Order.isNormalMemory ==
129 Other.Contents.Order.isNormalMemory &&
130 Contents.Order.isMustAlias == Other.Contents.Order.isMustAlias &&
131 Contents.Order.isArtificial == Other.Contents.Order.isArtificial;
133 assert(0 && "Invalid dependency kind!");
137 bool operator!=(const SDep &Other) const {
138 return !operator==(Other);
141 /// getLatency - Return the latency value for this edge, which roughly
142 /// means the minimum number of cycles that must elapse between the
143 /// predecessor and the successor, given that they have this edge
145 unsigned getLatency() const {
149 //// getSUnit - Return the SUnit to which this edge points.
150 SUnit *getSUnit() const {
151 return Dep.getPointer();
154 //// setSUnit - Assign the SUnit to which this edge points.
155 void setSUnit(SUnit *SU) {
159 /// getKind - Return an enum value representing the kind of the dependence.
160 Kind getKind() const {
164 /// isCtrl - Shorthand for getKind() != SDep::Data.
165 bool isCtrl() const {
166 return getKind() != Data;
169 /// isMustAlias - Test if this is an Order dependence that is marked
170 /// as "must alias", meaning that the SUnits at either end of the edge
171 /// have a memory dependence on a known memory location.
172 bool isMustAlias() const {
173 return getKind() == Order && Contents.Order.isMustAlias;
176 /// isArtificial - Test if this is an Order dependence that is marked
177 /// as "artificial", meaning it isn't necessary for correctness.
178 bool isArtificial() const {
179 return getKind() == Order && Contents.Order.isArtificial;
182 /// isAssignedRegDep - Test if this is a Data dependence that is
183 /// associated with a register.
184 bool isAssignedRegDep() const {
185 return getKind() == Data && Contents.Reg != 0;
188 /// getReg - Return the register associated with this edge. This is
189 /// only valid on Data, Anti, and Output edges. On Data edges, this
190 /// value may be zero, meaning there is no associated register.
191 unsigned getReg() const {
192 assert((getKind() == Data || getKind() == Anti || getKind() == Output) &&
193 "getReg called on non-register dependence edge!");
197 /// setReg - Assign the associated register for this edge. This is
198 /// only valid on Data, Anti, and Output edges. On Anti and Output
199 /// edges, this value must not be zero. On Data edges, the value may
200 /// be zero, which would mean that no specific register is associated
202 void setReg(unsigned Reg) {
203 assert((getKind() == Data || getKind() == Anti || getKind() == Output) &&
204 "setReg called on non-register dependence edge!");
205 assert((getKind() != Anti || Reg != 0) &&
206 "SDep::Anti edge cannot use the zero register!");
207 assert((getKind() != Output || Reg != 0) &&
208 "SDep::Output edge cannot use the zero register!");
213 /// SUnit - Scheduling unit. This is a node in the scheduling DAG.
216 SDNode *Node; // Representative node.
217 MachineInstr *Instr; // Alternatively, a MachineInstr.
219 SUnit *OrigNode; // If not this, the node from which
220 // this node was cloned.
222 // Preds/Succs - The SUnits before/after us in the graph. The boolean value
223 // is true if the edge is a token chain edge, false if it is a value edge.
224 SmallVector<SDep, 4> Preds; // All sunit predecessors.
225 SmallVector<SDep, 4> Succs; // All sunit successors.
227 typedef SmallVector<SDep, 4>::iterator pred_iterator;
228 typedef SmallVector<SDep, 4>::iterator succ_iterator;
229 typedef SmallVector<SDep, 4>::const_iterator const_pred_iterator;
230 typedef SmallVector<SDep, 4>::const_iterator const_succ_iterator;
232 unsigned NodeNum; // Entry # of node in the node vector.
233 unsigned NodeQueueId; // Queue id of node.
234 unsigned short Latency; // Node latency.
235 short NumPreds; // # of SDep::Data preds.
236 short NumSuccs; // # of SDep::Data sucss.
237 short NumPredsLeft; // # of preds not scheduled.
238 short NumSuccsLeft; // # of succs not scheduled.
239 bool isTwoAddress : 1; // Is a two-address instruction.
240 bool isCommutable : 1; // Is a commutable instruction.
241 bool hasPhysRegDefs : 1; // Has physreg defs that are being used.
242 bool isPending : 1; // True once pending.
243 bool isAvailable : 1; // True once available.
244 bool isScheduled : 1; // True once scheduled.
245 bool isScheduleHigh : 1; // True if preferable to schedule high.
247 bool isDepthCurrent : 1; // True if Depth is current.
248 bool isHeightCurrent : 1; // True if Height is current.
249 unsigned Depth; // Node depth.
250 unsigned Height; // Node height.
252 const TargetRegisterClass *CopyDstRC; // Is a special copy node if not null.
253 const TargetRegisterClass *CopySrcRC;
255 /// SUnit - Construct an SUnit for pre-regalloc scheduling to represent
256 /// an SDNode and any nodes flagged to it.
257 SUnit(SDNode *node, unsigned nodenum)
258 : Node(node), Instr(0), OrigNode(0), NodeNum(nodenum), NodeQueueId(0),
259 Latency(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0), NumSuccsLeft(0),
260 isTwoAddress(false), isCommutable(false), hasPhysRegDefs(false),
261 isPending(false), isAvailable(false), isScheduled(false),
262 isScheduleHigh(false), isDepthCurrent(false), isHeightCurrent(false),
264 CopyDstRC(NULL), CopySrcRC(NULL) {}
266 /// SUnit - Construct an SUnit for post-regalloc scheduling to represent
268 SUnit(MachineInstr *instr, unsigned nodenum)
269 : Node(0), Instr(instr), OrigNode(0), NodeNum(nodenum), NodeQueueId(0),
270 Latency(0), NumPreds(0), NumSuccs(0), NumPredsLeft(0), NumSuccsLeft(0),
271 isTwoAddress(false), isCommutable(false), hasPhysRegDefs(false),
272 isPending(false), isAvailable(false), isScheduled(false),
273 isScheduleHigh(false), isDepthCurrent(false), isHeightCurrent(false),
275 CopyDstRC(NULL), CopySrcRC(NULL) {}
277 /// setNode - Assign the representative SDNode for this SUnit.
278 /// This may be used during pre-regalloc scheduling.
279 void setNode(SDNode *N) {
280 assert(!Instr && "Setting SDNode of SUnit with MachineInstr!");
284 /// getNode - Return the representative SDNode for this SUnit.
285 /// This may be used during pre-regalloc scheduling.
286 SDNode *getNode() const {
287 assert(!Instr && "Reading SDNode of SUnit with MachineInstr!");
291 /// setInstr - Assign the instruction for the SUnit.
292 /// This may be used during post-regalloc scheduling.
293 void setInstr(MachineInstr *MI) {
294 assert(!Node && "Setting MachineInstr of SUnit with SDNode!");
298 /// getInstr - Return the representative MachineInstr for this SUnit.
299 /// This may be used during post-regalloc scheduling.
300 MachineInstr *getInstr() const {
301 assert(!Node && "Reading MachineInstr of SUnit with SDNode!");
305 /// addPred - This adds the specified edge as a pred of the current node if
306 /// not already. It also adds the current node as a successor of the
308 void addPred(const SDep &D);
310 /// removePred - This removes the specified edge as a pred of the current
311 /// node if it exists. It also removes the current node as a successor of
312 /// the specified node.
313 void removePred(const SDep &D);
315 /// getDepth - Return the depth of this node, which is the length of the
316 /// maximum path up to any node with has no predecessors.
317 unsigned getDepth() const {
318 if (!isDepthCurrent) const_cast<SUnit *>(this)->ComputeDepth();
322 /// getHeight - Return the height of this node, which is the length of the
323 /// maximum path down to any node with has no successors.
324 unsigned getHeight() const {
325 if (!isHeightCurrent) const_cast<SUnit *>(this)->ComputeHeight();
329 /// setDepthToAtLeast - If NewDepth is greater than this node's depth
330 /// value, set it to be the new depth value. This also recursively
331 /// marks successor nodes dirty.
332 void setDepthToAtLeast(unsigned NewDepth);
334 /// setDepthToAtLeast - If NewDepth is greater than this node's depth
335 /// value, set it to be the new height value. This also recursively
336 /// marks predecessor nodes dirty.
337 void setHeightToAtLeast(unsigned NewHeight);
339 /// setDepthDirty - Set a flag in this node to indicate that its
340 /// stored Depth value will require recomputation the next time
341 /// getDepth() is called.
342 void setDepthDirty();
344 /// setHeightDirty - Set a flag in this node to indicate that its
345 /// stored Height value will require recomputation the next time
346 /// getHeight() is called.
347 void setHeightDirty();
349 /// isPred - Test if node N is a predecessor of this node.
350 bool isPred(SUnit *N) {
351 for (unsigned i = 0, e = (unsigned)Preds.size(); i != e; ++i)
352 if (Preds[i].getSUnit() == N)
357 /// isSucc - Test if node N is a successor of this node.
358 bool isSucc(SUnit *N) {
359 for (unsigned i = 0, e = (unsigned)Succs.size(); i != e; ++i)
360 if (Succs[i].getSUnit() == N)
365 void dump(const ScheduleDAG *G) const;
366 void dumpAll(const ScheduleDAG *G) const;
367 void print(raw_ostream &O, const ScheduleDAG *G) const;
371 void ComputeHeight();
374 //===--------------------------------------------------------------------===//
375 /// SchedulingPriorityQueue - This interface is used to plug different
376 /// priorities computation algorithms into the list scheduler. It implements
377 /// the interface of a standard priority queue, where nodes are inserted in
378 /// arbitrary order and returned in priority order. The computation of the
379 /// priority and the representation of the queue are totally up to the
380 /// implementation to decide.
382 class SchedulingPriorityQueue {
384 virtual ~SchedulingPriorityQueue() {}
386 virtual void initNodes(std::vector<SUnit> &SUnits) = 0;
387 virtual void addNode(const SUnit *SU) = 0;
388 virtual void updateNode(const SUnit *SU) = 0;
389 virtual void releaseState() = 0;
391 virtual unsigned size() const = 0;
392 virtual bool empty() const = 0;
393 virtual void push(SUnit *U) = 0;
395 virtual void push_all(const std::vector<SUnit *> &Nodes) = 0;
396 virtual SUnit *pop() = 0;
398 virtual void remove(SUnit *SU) = 0;
400 /// ScheduledNode - As each node is scheduled, this method is invoked. This
401 /// allows the priority function to adjust the priority of related
402 /// unscheduled nodes, for example.
404 virtual void ScheduledNode(SUnit *) {}
406 virtual void UnscheduledNode(SUnit *) {}
411 SelectionDAG *DAG; // DAG of the current basic block
412 MachineBasicBlock *BB; // Current basic block
413 const TargetMachine &TM; // Target processor
414 const TargetInstrInfo *TII; // Target instruction information
415 const TargetRegisterInfo *TRI; // Target processor register info
416 TargetLowering *TLI; // Target lowering info
417 MachineFunction *MF; // Machine function
418 MachineRegisterInfo &MRI; // Virtual/real register map
419 MachineConstantPool *ConstPool; // Target constant pool
420 std::vector<SUnit*> Sequence; // The schedule. Null SUnit*'s
421 // represent noop instructions.
422 std::vector<SUnit> SUnits; // The scheduling units.
424 ScheduleDAG(SelectionDAG *dag, MachineBasicBlock *bb,
425 const TargetMachine &tm);
427 virtual ~ScheduleDAG();
429 /// viewGraph - Pop up a GraphViz/gv window with the ScheduleDAG rendered
434 /// Run - perform scheduling.
438 /// BuildSchedUnits - Build SUnits and set up their Preds and Succs
439 /// to form the scheduling dependency graph.
441 virtual void BuildSchedUnits() = 0;
443 /// ComputeLatency - Compute node latency.
445 virtual void ComputeLatency(SUnit *SU) = 0;
448 /// EmitNoop - Emit a noop instruction.
453 virtual MachineBasicBlock *EmitSchedule() = 0;
455 void dumpSchedule() const;
457 /// Schedule - Order nodes according to selected style, filling
458 /// in the Sequence member.
460 virtual void Schedule() = 0;
462 virtual void dumpNode(const SUnit *SU) const = 0;
464 /// getGraphNodeLabel - Return a label for an SUnit node in a visualization
465 /// of the ScheduleDAG.
466 virtual std::string getGraphNodeLabel(const SUnit *SU) const = 0;
468 /// addCustomGraphFeatures - Add custom features for a visualization of
470 virtual void addCustomGraphFeatures(GraphWriter<ScheduleDAG*> &) const {}
473 /// VerifySchedule - Verify that all SUnits were scheduled and that
474 /// their state is consistent.
475 void VerifySchedule(bool isBottomUp);
479 void AddMemOperand(MachineInstr *MI, const MachineMemOperand &MO);
481 void EmitCrossRCCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap);
483 /// ForceUnitLatencies - Return true if all scheduling edges should be given a
484 /// latency value of one. The default is to return false; schedulers may
485 /// override this as needed.
486 virtual bool ForceUnitLatencies() const { return false; }
489 /// EmitLiveInCopy - Emit a copy for a live in physical register. If the
490 /// physical register has only a single copy use, then coalesced the copy
492 void EmitLiveInCopy(MachineBasicBlock *MBB,
493 MachineBasicBlock::iterator &InsertPos,
494 unsigned VirtReg, unsigned PhysReg,
495 const TargetRegisterClass *RC,
496 DenseMap<MachineInstr*, unsigned> &CopyRegMap);
498 /// EmitLiveInCopies - If this is the first basic block in the function,
499 /// and if it has live ins that need to be copied into vregs, emit the
500 /// copies into the top of the block.
501 void EmitLiveInCopies(MachineBasicBlock *MBB);
504 class SUnitIterator : public forward_iterator<SUnit, ptrdiff_t> {
508 SUnitIterator(SUnit *N, unsigned Op) : Node(N), Operand(Op) {}
510 bool operator==(const SUnitIterator& x) const {
511 return Operand == x.Operand;
513 bool operator!=(const SUnitIterator& x) const { return !operator==(x); }
515 const SUnitIterator &operator=(const SUnitIterator &I) {
516 assert(I.Node == Node && "Cannot assign iterators to two different nodes!");
521 pointer operator*() const {
522 return Node->Preds[Operand].getSUnit();
524 pointer operator->() const { return operator*(); }
526 SUnitIterator& operator++() { // Preincrement
530 SUnitIterator operator++(int) { // Postincrement
531 SUnitIterator tmp = *this; ++*this; return tmp;
534 static SUnitIterator begin(SUnit *N) { return SUnitIterator(N, 0); }
535 static SUnitIterator end (SUnit *N) {
536 return SUnitIterator(N, (unsigned)N->Preds.size());
539 unsigned getOperand() const { return Operand; }
540 const SUnit *getNode() const { return Node; }
541 /// isCtrlDep - Test if this is not an SDep::Data dependence.
542 bool isCtrlDep() const {
543 return getSDep().isCtrl();
545 bool isArtificialDep() const {
546 return getSDep().isArtificial();
548 const SDep &getSDep() const {
549 return Node->Preds[Operand];
553 template <> struct GraphTraits<SUnit*> {
554 typedef SUnit NodeType;
555 typedef SUnitIterator ChildIteratorType;
556 static inline NodeType *getEntryNode(SUnit *N) { return N; }
557 static inline ChildIteratorType child_begin(NodeType *N) {
558 return SUnitIterator::begin(N);
560 static inline ChildIteratorType child_end(NodeType *N) {
561 return SUnitIterator::end(N);
565 template <> struct GraphTraits<ScheduleDAG*> : public GraphTraits<SUnit*> {
566 typedef std::vector<SUnit>::iterator nodes_iterator;
567 static nodes_iterator nodes_begin(ScheduleDAG *G) {
568 return G->SUnits.begin();
570 static nodes_iterator nodes_end(ScheduleDAG *G) {
571 return G->SUnits.end();
575 /// ScheduleDAGTopologicalSort is a class that computes a topological
576 /// ordering for SUnits and provides methods for dynamically updating
577 /// the ordering as new edges are added.
579 /// This allows a very fast implementation of IsReachable, for example.
581 class ScheduleDAGTopologicalSort {
582 /// SUnits - A reference to the ScheduleDAG's SUnits.
583 std::vector<SUnit> &SUnits;
585 /// Index2Node - Maps topological index to the node number.
586 std::vector<int> Index2Node;
587 /// Node2Index - Maps the node number to its topological index.
588 std::vector<int> Node2Index;
589 /// Visited - a set of nodes visited during a DFS traversal.
592 /// DFS - make a DFS traversal and mark all nodes affected by the
593 /// edge insertion. These nodes will later get new topological indexes
594 /// by means of the Shift method.
595 void DFS(const SUnit *SU, int UpperBound, bool& HasLoop);
597 /// Shift - reassign topological indexes for the nodes in the DAG
598 /// to preserve the topological ordering.
599 void Shift(BitVector& Visited, int LowerBound, int UpperBound);
601 /// Allocate - assign the topological index to the node n.
602 void Allocate(int n, int index);
605 explicit ScheduleDAGTopologicalSort(std::vector<SUnit> &SUnits);
607 /// InitDAGTopologicalSorting - create the initial topological
608 /// ordering from the DAG to be scheduled.
609 void InitDAGTopologicalSorting();
611 /// IsReachable - Checks if SU is reachable from TargetSU.
612 bool IsReachable(const SUnit *SU, const SUnit *TargetSU);
614 /// WillCreateCycle - Returns true if adding an edge from SU to TargetSU
615 /// will create a cycle.
616 bool WillCreateCycle(SUnit *SU, SUnit *TargetSU);
618 /// AddPred - Updates the topological ordering to accomodate an edge
619 /// to be added from SUnit X to SUnit Y.
620 void AddPred(SUnit *Y, SUnit *X);
622 /// RemovePred - Updates the topological ordering to accomodate an
623 /// an edge to be removed from the specified node N from the predecessors
624 /// of the current node M.
625 void RemovePred(SUnit *M, SUnit *N);
627 typedef std::vector<int>::iterator iterator;
628 typedef std::vector<int>::const_iterator const_iterator;
629 iterator begin() { return Index2Node.begin(); }
630 const_iterator begin() const { return Index2Node.begin(); }
631 iterator end() { return Index2Node.end(); }
632 const_iterator end() const { return Index2Node.end(); }
634 typedef std::vector<int>::reverse_iterator reverse_iterator;
635 typedef std::vector<int>::const_reverse_iterator const_reverse_iterator;
636 reverse_iterator rbegin() { return Index2Node.rbegin(); }
637 const_reverse_iterator rbegin() const { return Index2Node.rbegin(); }
638 reverse_iterator rend() { return Index2Node.rend(); }
639 const_reverse_iterator rend() const { return Index2Node.rend(); }