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 SelectionDAG-based instruction scheduler.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CODEGEN_SCHEDULEDAG_H
16 #define LLVM_CODEGEN_SCHEDULEDAG_H
18 #include "llvm/CodeGen/SelectionDAG.h"
19 #include "llvm/ADT/DenseMap.h"
20 #include "llvm/ADT/GraphTraits.h"
21 #include "llvm/ADT/SmallSet.h"
26 class MachineConstantPool;
27 class MachineModuleInfo;
28 class MachineRegisterInfo;
32 class SelectionDAGISel;
33 class TargetInstrInfo;
34 class TargetInstrDescriptor;
36 class TargetRegisterClass;
38 /// HazardRecognizer - This determines whether or not an instruction can be
39 /// issued this cycle, and whether or not a noop needs to be inserted to handle
41 class HazardRecognizer {
43 virtual ~HazardRecognizer();
46 NoHazard, // This instruction can be emitted at this cycle.
47 Hazard, // This instruction can't be emitted at this cycle.
48 NoopHazard // This instruction can't be emitted, and needs noops.
51 /// getHazardType - Return the hazard type of emitting this node. There are
52 /// three possible results. Either:
53 /// * NoHazard: it is legal to issue this instruction on this cycle.
54 /// * Hazard: issuing this instruction would stall the machine. If some
55 /// other instruction is available, issue it first.
56 /// * NoopHazard: issuing this instruction would break the program. If
57 /// some other instruction can be issued, do so, otherwise issue a noop.
58 virtual HazardType getHazardType(SDNode *Node) {
62 /// EmitInstruction - This callback is invoked when an instruction is
63 /// emitted, to advance the hazard state.
64 virtual void EmitInstruction(SDNode *Node) {
67 /// AdvanceCycle - This callback is invoked when no instructions can be
68 /// issued on this cycle without a hazard. This should increment the
69 /// internal state of the hazard recognizer so that previously "Hazard"
70 /// instructions will now not be hazards.
71 virtual void AdvanceCycle() {
74 /// EmitNoop - This callback is invoked when a noop was added to the
75 /// instruction stream.
76 virtual void EmitNoop() {
80 /// SDep - Scheduling dependency. It keeps track of dependent nodes,
81 /// cost of the depdenency, etc.
83 SUnit *Dep; // Dependent - either a predecessor or a successor.
84 unsigned Reg; // If non-zero, this dep is a phy register dependency.
85 int Cost; // Cost of the dependency.
86 bool isCtrl : 1; // True iff it's a control dependency.
87 bool isSpecial : 1; // True iff it's a special ctrl dep added during sched.
88 SDep(SUnit *d, unsigned r, int t, bool c, bool s)
89 : Dep(d), Reg(r), Cost(t), isCtrl(c), isSpecial(s) {}
92 /// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
93 /// a group of nodes flagged together.
95 SDNode *Node; // Representative node.
96 SmallVector<SDNode*,4> FlaggedNodes;// All nodes flagged to Node.
97 unsigned InstanceNo; // Instance#. One SDNode can be multiple
98 // SUnit due to cloning.
100 // Preds/Succs - The SUnits before/after us in the graph. The boolean value
101 // is true if the edge is a token chain edge, false if it is a value edge.
102 SmallVector<SDep, 4> Preds; // All sunit predecessors.
103 SmallVector<SDep, 4> Succs; // All sunit successors.
105 typedef SmallVector<SDep, 4>::iterator pred_iterator;
106 typedef SmallVector<SDep, 4>::iterator succ_iterator;
107 typedef SmallVector<SDep, 4>::const_iterator const_pred_iterator;
108 typedef SmallVector<SDep, 4>::const_iterator const_succ_iterator;
110 unsigned NodeNum; // Entry # of node in the node vector.
111 unsigned short Latency; // Node latency.
112 short NumPreds; // # of preds.
113 short NumSuccs; // # of sucss.
114 short NumPredsLeft; // # of preds not scheduled.
115 short NumSuccsLeft; // # of succs not scheduled.
116 bool isTwoAddress : 1; // Is a two-address instruction.
117 bool isCommutable : 1; // Is a commutable instruction.
118 bool hasPhysRegDefs : 1; // Has physreg defs that are being used.
119 bool isPending : 1; // True once pending.
120 bool isAvailable : 1; // True once available.
121 bool isScheduled : 1; // True once scheduled.
122 unsigned CycleBound; // Upper/lower cycle to be scheduled at.
123 unsigned Cycle; // Once scheduled, the cycle of the op.
124 unsigned Depth; // Node depth;
125 unsigned Height; // Node height;
126 const TargetRegisterClass *CopyDstRC; // Is a special copy node if not null.
127 const TargetRegisterClass *CopySrcRC;
129 SUnit(SDNode *node, unsigned nodenum)
130 : Node(node), InstanceNo(0), NodeNum(nodenum), Latency(0),
131 NumPreds(0), NumSuccs(0), NumPredsLeft(0), NumSuccsLeft(0),
132 isTwoAddress(false), isCommutable(false), hasPhysRegDefs(false),
133 isPending(false), isAvailable(false), isScheduled(false),
134 CycleBound(0), Cycle(0), Depth(0), Height(0),
135 CopyDstRC(NULL), CopySrcRC(NULL) {}
137 /// addPred - This adds the specified node as a pred of the current node if
138 /// not already. This returns true if this is a new pred.
139 bool addPred(SUnit *N, bool isCtrl, bool isSpecial,
140 unsigned PhyReg = 0, int Cost = 1) {
141 for (unsigned i = 0, e = Preds.size(); i != e; ++i)
142 if (Preds[i].Dep == N &&
143 Preds[i].isCtrl == isCtrl && Preds[i].isSpecial == isSpecial)
145 Preds.push_back(SDep(N, PhyReg, Cost, isCtrl, isSpecial));
146 N->Succs.push_back(SDep(this, PhyReg, Cost, isCtrl, isSpecial));
158 bool removePred(SUnit *N, bool isCtrl, bool isSpecial) {
159 for (SmallVector<SDep, 4>::iterator I = Preds.begin(), E = Preds.end();
161 if (I->Dep == N && I->isCtrl == isCtrl && I->isSpecial == isSpecial) {
162 bool FoundSucc = false;
163 for (SmallVector<SDep, 4>::iterator II = N->Succs.begin(),
164 EE = N->Succs.end(); II != EE; ++II)
165 if (II->Dep == this &&
166 II->isCtrl == isCtrl && II->isSpecial == isSpecial) {
171 assert(FoundSucc && "Mismatching preds / succs lists!");
186 bool isPred(SUnit *N) {
187 for (unsigned i = 0, e = Preds.size(); i != e; ++i)
188 if (Preds[i].Dep == N)
193 bool isSucc(SUnit *N) {
194 for (unsigned i = 0, e = Succs.size(); i != e; ++i)
195 if (Succs[i].Dep == N)
200 void dump(const SelectionDAG *G) const;
201 void dumpAll(const SelectionDAG *G) const;
204 //===--------------------------------------------------------------------===//
205 /// SchedulingPriorityQueue - This interface is used to plug different
206 /// priorities computation algorithms into the list scheduler. It implements
207 /// the interface of a standard priority queue, where nodes are inserted in
208 /// arbitrary order and returned in priority order. The computation of the
209 /// priority and the representation of the queue are totally up to the
210 /// implementation to decide.
212 class SchedulingPriorityQueue {
214 virtual ~SchedulingPriorityQueue() {}
216 virtual void initNodes(DenseMap<SDNode*, std::vector<SUnit*> > &SUMap,
217 std::vector<SUnit> &SUnits) = 0;
218 virtual void addNode(const SUnit *SU) = 0;
219 virtual void updateNode(const SUnit *SU) = 0;
220 virtual void releaseState() = 0;
222 virtual unsigned size() const = 0;
223 virtual bool empty() const = 0;
224 virtual void push(SUnit *U) = 0;
226 virtual void push_all(const std::vector<SUnit *> &Nodes) = 0;
227 virtual SUnit *pop() = 0;
229 virtual void remove(SUnit *SU) = 0;
231 /// ScheduledNode - As each node is scheduled, this method is invoked. This
232 /// allows the priority function to adjust the priority of node that have
233 /// already been emitted.
234 virtual void ScheduledNode(SUnit *Node) {}
236 virtual void UnscheduledNode(SUnit *Node) {}
241 SelectionDAG &DAG; // DAG of the current basic block
242 MachineBasicBlock *BB; // Current basic block
243 const TargetMachine &TM; // Target processor
244 const TargetInstrInfo *TII; // Target instruction information
245 const MRegisterInfo *MRI; // Target processor register info
246 MachineRegisterInfo &RegInfo; // Virtual/real register map
247 MachineConstantPool *ConstPool; // Target constant pool
248 std::vector<SUnit*> Sequence; // The schedule. Null SUnit*'s
249 // represent noop instructions.
250 DenseMap<SDNode*, std::vector<SUnit*> > SUnitMap;
251 // SDNode to SUnit mapping (n -> n).
252 std::vector<SUnit> SUnits; // The scheduling units.
253 SmallSet<SDNode*, 16> CommuteSet; // Nodes the should be commuted.
255 ScheduleDAG(SelectionDAG &dag, MachineBasicBlock *bb,
256 const TargetMachine &tm);
258 virtual ~ScheduleDAG() {}
260 /// viewGraph - Pop up a GraphViz/gv window with the ScheduleDAG rendered
265 /// Run - perform scheduling.
267 MachineBasicBlock *Run();
269 /// isPassiveNode - Return true if the node is a non-scheduled leaf.
271 static bool isPassiveNode(SDNode *Node) {
272 if (isa<ConstantSDNode>(Node)) return true;
273 if (isa<RegisterSDNode>(Node)) return true;
274 if (isa<GlobalAddressSDNode>(Node)) return true;
275 if (isa<BasicBlockSDNode>(Node)) return true;
276 if (isa<FrameIndexSDNode>(Node)) return true;
277 if (isa<ConstantPoolSDNode>(Node)) return true;
278 if (isa<JumpTableSDNode>(Node)) return true;
279 if (isa<ExternalSymbolSDNode>(Node)) return true;
283 /// NewSUnit - Creates a new SUnit and return a ptr to it.
285 SUnit *NewSUnit(SDNode *N) {
286 SUnits.push_back(SUnit(N, SUnits.size()));
287 return &SUnits.back();
290 /// Clone - Creates a clone of the specified SUnit. It does not copy the
291 /// predecessors / successors info nor the temporary scheduling states.
292 SUnit *Clone(SUnit *N);
294 /// BuildSchedUnits - Build SUnits from the selection dag that we are input.
295 /// This SUnit graph is similar to the SelectionDAG, but represents flagged
296 /// together nodes with a single SUnit.
297 void BuildSchedUnits();
299 /// ComputeLatency - Compute node latency.
301 void ComputeLatency(SUnit *SU);
303 /// CalculateDepths, CalculateHeights - Calculate node depth / height.
305 void CalculateDepths();
306 void CalculateHeights();
308 /// CountResults - The results of target nodes have register or immediate
309 /// operands first, then an optional chain, and optional flag operands
310 /// (which do not go into the machine instrs.)
311 static unsigned CountResults(SDNode *Node);
313 /// CountOperands The inputs to target nodes have any actual inputs first,
314 /// followed by an optional chain operand, then flag operands. Compute the
315 /// number of actual operands that will go into the machine instr.
316 static unsigned CountOperands(SDNode *Node);
318 /// EmitNode - Generate machine code for an node and needed dependencies.
319 /// VRBaseMap contains, for each already emitted node, the first virtual
320 /// register number for the results of the node.
322 void EmitNode(SDNode *Node, unsigned InstNo,
323 DenseMap<SDOperand, unsigned> &VRBaseMap);
325 /// EmitNoop - Emit a noop instruction.
329 void EmitCrossRCCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap);
331 /// EmitCopyFromReg - Generate machine code for an CopyFromReg node or an
332 /// implicit physical register output.
333 void EmitCopyFromReg(SDNode *Node, unsigned ResNo, unsigned InstNo,
335 DenseMap<SDOperand, unsigned> &VRBaseMap);
337 void CreateVirtualRegisters(SDNode *Node, MachineInstr *MI,
338 const TargetInstrDescriptor &II,
339 DenseMap<SDOperand, unsigned> &VRBaseMap);
343 void dumpSchedule() const;
345 /// Schedule - Order nodes according to selected style.
347 virtual void Schedule() {}
350 /// EmitSubregNode - Generate machine code for subreg nodes.
352 void EmitSubregNode(SDNode *Node,
353 DenseMap<SDOperand, unsigned> &VRBaseMap);
355 void AddOperand(MachineInstr *MI, SDOperand Op, unsigned IIOpNum,
356 const TargetInstrDescriptor *II,
357 DenseMap<SDOperand, unsigned> &VRBaseMap);
360 /// createBURRListDAGScheduler - This creates a bottom up register usage
361 /// reduction list scheduler.
362 ScheduleDAG* createBURRListDAGScheduler(SelectionDAGISel *IS,
364 MachineBasicBlock *BB);
366 /// createTDRRListDAGScheduler - This creates a top down register usage
367 /// reduction list scheduler.
368 ScheduleDAG* createTDRRListDAGScheduler(SelectionDAGISel *IS,
370 MachineBasicBlock *BB);
372 /// createTDListDAGScheduler - This creates a top-down list scheduler with
373 /// a hazard recognizer.
374 ScheduleDAG* createTDListDAGScheduler(SelectionDAGISel *IS,
376 MachineBasicBlock *BB);
378 /// createDefaultScheduler - This creates an instruction scheduler appropriate
380 ScheduleDAG* createDefaultScheduler(SelectionDAGISel *IS,
382 MachineBasicBlock *BB);
384 class SUnitIterator : public forward_iterator<SUnit, ptrdiff_t> {
388 SUnitIterator(SUnit *N, unsigned Op) : Node(N), Operand(Op) {}
390 bool operator==(const SUnitIterator& x) const {
391 return Operand == x.Operand;
393 bool operator!=(const SUnitIterator& x) const { return !operator==(x); }
395 const SUnitIterator &operator=(const SUnitIterator &I) {
396 assert(I.Node == Node && "Cannot assign iterators to two different nodes!");
401 pointer operator*() const {
402 return Node->Preds[Operand].Dep;
404 pointer operator->() const { return operator*(); }
406 SUnitIterator& operator++() { // Preincrement
410 SUnitIterator operator++(int) { // Postincrement
411 SUnitIterator tmp = *this; ++*this; return tmp;
414 static SUnitIterator begin(SUnit *N) { return SUnitIterator(N, 0); }
415 static SUnitIterator end (SUnit *N) {
416 return SUnitIterator(N, N->Preds.size());
419 unsigned getOperand() const { return Operand; }
420 const SUnit *getNode() const { return Node; }
421 bool isCtrlDep() const { return Node->Preds[Operand].isCtrl; }
424 template <> struct GraphTraits<SUnit*> {
425 typedef SUnit NodeType;
426 typedef SUnitIterator ChildIteratorType;
427 static inline NodeType *getEntryNode(SUnit *N) { return N; }
428 static inline ChildIteratorType child_begin(NodeType *N) {
429 return SUnitIterator::begin(N);
431 static inline ChildIteratorType child_end(NodeType *N) {
432 return SUnitIterator::end(N);
436 template <> struct GraphTraits<ScheduleDAG*> : public GraphTraits<SUnit*> {
437 typedef std::vector<SUnit>::iterator nodes_iterator;
438 static nodes_iterator nodes_begin(ScheduleDAG *G) {
439 return G->SUnits.begin();
441 static nodes_iterator nodes_end(ScheduleDAG *G) {
442 return G->SUnits.end();