TargetInstrInfo.cpp revision b86a0cdb674549d8493043331cecd9cbf53b80da 
1//===-- TargetInstrInfo.cpp - Target Instruction Information --------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the TargetInstrInfo class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Target/TargetInstrInfo.h"
15#include "llvm/CodeGen/MachineFrameInfo.h"
16#include "llvm/CodeGen/MachineMemOperand.h"
17#include "llvm/CodeGen/MachineRegisterInfo.h"
18#include "llvm/CodeGen/PseudoSourceValue.h"
19#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
20#include "llvm/MC/MCAsmInfo.h"
21#include "llvm/MC/MCInstrItineraries.h"
22#include "llvm/Support/CommandLine.h"
23#include "llvm/Support/ErrorHandling.h"
24#include "llvm/Support/raw_ostream.h"
25#include "llvm/Target/TargetLowering.h"
26#include "llvm/Target/TargetMachine.h"
27#include "llvm/Target/TargetRegisterInfo.h"
28#include <cctype>
29using namespace llvm;
30
31static cl::opt<bool> DisableHazardRecognizer(
32  "disable-sched-hazard", cl::Hidden, cl::init(false),
33  cl::desc("Disable hazard detection during preRA scheduling"));
34
35TargetInstrInfo::~TargetInstrInfo() {
36}
37
38const TargetRegisterClass*
39TargetInstrInfo::getRegClass(const MCInstrDesc &MCID, unsigned OpNum,
40                             const TargetRegisterInfo *TRI,
41                             const MachineFunction &MF) const {
42  if (OpNum >= MCID.getNumOperands())
43    return 0;
44
45  short RegClass = MCID.OpInfo[OpNum].RegClass;
46  if (MCID.OpInfo[OpNum].isLookupPtrRegClass())
47    return TRI->getPointerRegClass(MF, RegClass);
48
49  // Instructions like INSERT_SUBREG do not have fixed register classes.
50  if (RegClass < 0)
51    return 0;
52
53  // Otherwise just look it up normally.
54  return TRI->getRegClass(RegClass);
55}
56
57/// insertNoop - Insert a noop into the instruction stream at the specified
58/// point.
59void TargetInstrInfo::insertNoop(MachineBasicBlock &MBB,
60                                 MachineBasicBlock::iterator MI) const {
61  llvm_unreachable("Target didn't implement insertNoop!");
62}
63
64/// Measure the specified inline asm to determine an approximation of its
65/// length.
66/// Comments (which run till the next SeparatorString or newline) do not
67/// count as an instruction.
68/// Any other non-whitespace text is considered an instruction, with
69/// multiple instructions separated by SeparatorString or newlines.
70/// Variable-length instructions are not handled here; this function
71/// may be overloaded in the target code to do that.
72unsigned TargetInstrInfo::getInlineAsmLength(const char *Str,
73                                             const MCAsmInfo &MAI) const {
74
75
76  // Count the number of instructions in the asm.
77  bool atInsnStart = true;
78  unsigned Length = 0;
79  for (; *Str; ++Str) {
80    if (*Str == '\n' || strncmp(Str, MAI.getSeparatorString(),
81                                strlen(MAI.getSeparatorString())) == 0)
82      atInsnStart = true;
83    if (atInsnStart && !std::isspace(static_cast<unsigned char>(*Str))) {
84      Length += MAI.getMaxInstLength();
85      atInsnStart = false;
86    }
87    if (atInsnStart && strncmp(Str, MAI.getCommentString(),
88                               strlen(MAI.getCommentString())) == 0)
89      atInsnStart = false;
90  }
91
92  return Length;
93}
94
95/// ReplaceTailWithBranchTo - Delete the instruction OldInst and everything
96/// after it, replacing it with an unconditional branch to NewDest.
97void
98TargetInstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
99                                         MachineBasicBlock *NewDest) const {
100  MachineBasicBlock *MBB = Tail->getParent();
101
102  // Remove all the old successors of MBB from the CFG.
103  while (!MBB->succ_empty())
104    MBB->removeSuccessor(MBB->succ_begin());
105
106  // Remove all the dead instructions from the end of MBB.
107  MBB->erase(Tail, MBB->end());
108
109  // If MBB isn't immediately before MBB, insert a branch to it.
110  if (++MachineFunction::iterator(MBB) != MachineFunction::iterator(NewDest))
111    InsertBranch(*MBB, NewDest, 0, SmallVector<MachineOperand, 0>(),
112                 Tail->getDebugLoc());
113  MBB->addSuccessor(NewDest);
114}
115
116// commuteInstruction - The default implementation of this method just exchanges
117// the two operands returned by findCommutedOpIndices.
118MachineInstr *TargetInstrInfo::commuteInstruction(MachineInstr *MI,
119                                                  bool NewMI) const {
120  const MCInstrDesc &MCID = MI->getDesc();
121  bool HasDef = MCID.getNumDefs();
122  if (HasDef && !MI->getOperand(0).isReg())
123    // No idea how to commute this instruction. Target should implement its own.
124    return 0;
125  unsigned Idx1, Idx2;
126  if (!findCommutedOpIndices(MI, Idx1, Idx2)) {
127    std::string msg;
128    raw_string_ostream Msg(msg);
129    Msg << "Don't know how to commute: " << *MI;
130    report_fatal_error(Msg.str());
131  }
132
133  assert(MI->getOperand(Idx1).isReg() && MI->getOperand(Idx2).isReg() &&
134         "This only knows how to commute register operands so far");
135  unsigned Reg0 = HasDef ? MI->getOperand(0).getReg() : 0;
136  unsigned Reg1 = MI->getOperand(Idx1).getReg();
137  unsigned Reg2 = MI->getOperand(Idx2).getReg();
138  unsigned SubReg0 = HasDef ? MI->getOperand(0).getSubReg() : 0;
139  unsigned SubReg1 = MI->getOperand(Idx1).getSubReg();
140  unsigned SubReg2 = MI->getOperand(Idx2).getSubReg();
141  bool Reg1IsKill = MI->getOperand(Idx1).isKill();
142  bool Reg2IsKill = MI->getOperand(Idx2).isKill();
143  // If destination is tied to either of the commuted source register, then
144  // it must be updated.
145  if (HasDef && Reg0 == Reg1 &&
146      MI->getDesc().getOperandConstraint(Idx1, MCOI::TIED_TO) == 0) {
147    Reg2IsKill = false;
148    Reg0 = Reg2;
149    SubReg0 = SubReg2;
150  } else if (HasDef && Reg0 == Reg2 &&
151             MI->getDesc().getOperandConstraint(Idx2, MCOI::TIED_TO) == 0) {
152    Reg1IsKill = false;
153    Reg0 = Reg1;
154    SubReg0 = SubReg1;
155  }
156
157  if (NewMI) {
158    // Create a new instruction.
159    MachineFunction &MF = *MI->getParent()->getParent();
160    MI = MF.CloneMachineInstr(MI);
161  }
162
163  if (HasDef) {
164    MI->getOperand(0).setReg(Reg0);
165    MI->getOperand(0).setSubReg(SubReg0);
166  }
167  MI->getOperand(Idx2).setReg(Reg1);
168  MI->getOperand(Idx1).setReg(Reg2);
169  MI->getOperand(Idx2).setSubReg(SubReg1);
170  MI->getOperand(Idx1).setSubReg(SubReg2);
171  MI->getOperand(Idx2).setIsKill(Reg1IsKill);
172  MI->getOperand(Idx1).setIsKill(Reg2IsKill);
173  return MI;
174}
175
176/// findCommutedOpIndices - If specified MI is commutable, return the two
177/// operand indices that would swap value. Return true if the instruction
178/// is not in a form which this routine understands.
179bool TargetInstrInfo::findCommutedOpIndices(MachineInstr *MI,
180                                            unsigned &SrcOpIdx1,
181                                            unsigned &SrcOpIdx2) const {
182  assert(!MI->isBundle() &&
183         "TargetInstrInfo::findCommutedOpIndices() can't handle bundles");
184
185  const MCInstrDesc &MCID = MI->getDesc();
186  if (!MCID.isCommutable())
187    return false;
188  // This assumes v0 = op v1, v2 and commuting would swap v1 and v2. If this
189  // is not true, then the target must implement this.
190  SrcOpIdx1 = MCID.getNumDefs();
191  SrcOpIdx2 = SrcOpIdx1 + 1;
192  if (!MI->getOperand(SrcOpIdx1).isReg() ||
193      !MI->getOperand(SrcOpIdx2).isReg())
194    // No idea.
195    return false;
196  return true;
197}
198
199
200bool
201TargetInstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
202  if (!MI->isTerminator()) return false;
203
204  // Conditional branch is a special case.
205  if (MI->isBranch() && !MI->isBarrier())
206    return true;
207  if (!MI->isPredicable())
208    return true;
209  return !isPredicated(MI);
210}
211
212
213bool TargetInstrInfo::PredicateInstruction(MachineInstr *MI,
214                            const SmallVectorImpl<MachineOperand> &Pred) const {
215  bool MadeChange = false;
216
217  assert(!MI->isBundle() &&
218         "TargetInstrInfo::PredicateInstruction() can't handle bundles");
219
220  const MCInstrDesc &MCID = MI->getDesc();
221  if (!MI->isPredicable())
222    return false;
223
224  for (unsigned j = 0, i = 0, e = MI->getNumOperands(); i != e; ++i) {
225    if (MCID.OpInfo[i].isPredicate()) {
226      MachineOperand &MO = MI->getOperand(i);
227      if (MO.isReg()) {
228        MO.setReg(Pred[j].getReg());
229        MadeChange = true;
230      } else if (MO.isImm()) {
231        MO.setImm(Pred[j].getImm());
232        MadeChange = true;
233      } else if (MO.isMBB()) {
234        MO.setMBB(Pred[j].getMBB());
235        MadeChange = true;
236      }
237      ++j;
238    }
239  }
240  return MadeChange;
241}
242
243bool TargetInstrInfo::hasLoadFromStackSlot(const MachineInstr *MI,
244                                           const MachineMemOperand *&MMO,
245                                           int &FrameIndex) const {
246  for (MachineInstr::mmo_iterator o = MI->memoperands_begin(),
247         oe = MI->memoperands_end();
248       o != oe;
249       ++o) {
250    if ((*o)->isLoad() && (*o)->getValue())
251      if (const FixedStackPseudoSourceValue *Value =
252          dyn_cast<const FixedStackPseudoSourceValue>((*o)->getValue())) {
253        FrameIndex = Value->getFrameIndex();
254        MMO = *o;
255        return true;
256      }
257  }
258  return false;
259}
260
261bool TargetInstrInfo::hasStoreToStackSlot(const MachineInstr *MI,
262                                          const MachineMemOperand *&MMO,
263                                          int &FrameIndex) const {
264  for (MachineInstr::mmo_iterator o = MI->memoperands_begin(),
265         oe = MI->memoperands_end();
266       o != oe;
267       ++o) {
268    if ((*o)->isStore() && (*o)->getValue())
269      if (const FixedStackPseudoSourceValue *Value =
270          dyn_cast<const FixedStackPseudoSourceValue>((*o)->getValue())) {
271        FrameIndex = Value->getFrameIndex();
272        MMO = *o;
273        return true;
274      }
275  }
276  return false;
277}
278
279void TargetInstrInfo::reMaterialize(MachineBasicBlock &MBB,
280                                    MachineBasicBlock::iterator I,
281                                    unsigned DestReg,
282                                    unsigned SubIdx,
283                                    const MachineInstr *Orig,
284                                    const TargetRegisterInfo &TRI) const {
285  MachineInstr *MI = MBB.getParent()->CloneMachineInstr(Orig);
286  MI->substituteRegister(MI->getOperand(0).getReg(), DestReg, SubIdx, TRI);
287  MBB.insert(I, MI);
288}
289
290bool
291TargetInstrInfo::produceSameValue(const MachineInstr *MI0,
292                                  const MachineInstr *MI1,
293                                  const MachineRegisterInfo *MRI) const {
294  return MI0->isIdenticalTo(MI1, MachineInstr::IgnoreVRegDefs);
295}
296
297MachineInstr *TargetInstrInfo::duplicate(MachineInstr *Orig,
298                                         MachineFunction &MF) const {
299  assert(!Orig->isNotDuplicable() &&
300         "Instruction cannot be duplicated");
301  return MF.CloneMachineInstr(Orig);
302}
303
304// If the COPY instruction in MI can be folded to a stack operation, return
305// the register class to use.
306static const TargetRegisterClass *canFoldCopy(const MachineInstr *MI,
307                                              unsigned FoldIdx) {
308  assert(MI->isCopy() && "MI must be a COPY instruction");
309  if (MI->getNumOperands() != 2)
310    return 0;
311  assert(FoldIdx<2 && "FoldIdx refers no nonexistent operand");
312
313  const MachineOperand &FoldOp = MI->getOperand(FoldIdx);
314  const MachineOperand &LiveOp = MI->getOperand(1-FoldIdx);
315
316  if (FoldOp.getSubReg() || LiveOp.getSubReg())
317    return 0;
318
319  unsigned FoldReg = FoldOp.getReg();
320  unsigned LiveReg = LiveOp.getReg();
321
322  assert(TargetRegisterInfo::isVirtualRegister(FoldReg) &&
323         "Cannot fold physregs");
324
325  const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
326  const TargetRegisterClass *RC = MRI.getRegClass(FoldReg);
327
328  if (TargetRegisterInfo::isPhysicalRegister(LiveOp.getReg()))
329    return RC->contains(LiveOp.getReg()) ? RC : 0;
330
331  if (RC->hasSubClassEq(MRI.getRegClass(LiveReg)))
332    return RC;
333
334  // FIXME: Allow folding when register classes are memory compatible.
335  return 0;
336}
337
338bool TargetInstrInfo::
339canFoldMemoryOperand(const MachineInstr *MI,
340                     const SmallVectorImpl<unsigned> &Ops) const {
341  return MI->isCopy() && Ops.size() == 1 && canFoldCopy(MI, Ops[0]);
342}
343
344/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
345/// slot into the specified machine instruction for the specified operand(s).
346/// If this is possible, a new instruction is returned with the specified
347/// operand folded, otherwise NULL is returned. The client is responsible for
348/// removing the old instruction and adding the new one in the instruction
349/// stream.
350MachineInstr*
351TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
352                                   const SmallVectorImpl<unsigned> &Ops,
353                                   int FI) const {
354  unsigned Flags = 0;
355  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
356    if (MI->getOperand(Ops[i]).isDef())
357      Flags |= MachineMemOperand::MOStore;
358    else
359      Flags |= MachineMemOperand::MOLoad;
360
361  MachineBasicBlock *MBB = MI->getParent();
362  assert(MBB && "foldMemoryOperand needs an inserted instruction");
363  MachineFunction &MF = *MBB->getParent();
364
365  // Ask the target to do the actual folding.
366  if (MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, FI)) {
367    // Add a memory operand, foldMemoryOperandImpl doesn't do that.
368    assert((!(Flags & MachineMemOperand::MOStore) ||
369            NewMI->mayStore()) &&
370           "Folded a def to a non-store!");
371    assert((!(Flags & MachineMemOperand::MOLoad) ||
372            NewMI->mayLoad()) &&
373           "Folded a use to a non-load!");
374    const MachineFrameInfo &MFI = *MF.getFrameInfo();
375    assert(MFI.getObjectOffset(FI) != -1);
376    MachineMemOperand *MMO =
377      MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FI),
378                              Flags, MFI.getObjectSize(FI),
379                              MFI.getObjectAlignment(FI));
380    NewMI->addMemOperand(MF, MMO);
381
382    // FIXME: change foldMemoryOperandImpl semantics to also insert NewMI.
383    return MBB->insert(MI, NewMI);
384  }
385
386  // Straight COPY may fold as load/store.
387  if (!MI->isCopy() || Ops.size() != 1)
388    return 0;
389
390  const TargetRegisterClass *RC = canFoldCopy(MI, Ops[0]);
391  if (!RC)
392    return 0;
393
394  const MachineOperand &MO = MI->getOperand(1-Ops[0]);
395  MachineBasicBlock::iterator Pos = MI;
396  const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo();
397
398  if (Flags == MachineMemOperand::MOStore)
399    storeRegToStackSlot(*MBB, Pos, MO.getReg(), MO.isKill(), FI, RC, TRI);
400  else
401    loadRegFromStackSlot(*MBB, Pos, MO.getReg(), FI, RC, TRI);
402  return --Pos;
403}
404
405/// foldMemoryOperand - Same as the previous version except it allows folding
406/// of any load and store from / to any address, not just from a specific
407/// stack slot.
408MachineInstr*
409TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
410                                   const SmallVectorImpl<unsigned> &Ops,
411                                   MachineInstr* LoadMI) const {
412  assert(LoadMI->canFoldAsLoad() && "LoadMI isn't foldable!");
413#ifndef NDEBUG
414  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
415    assert(MI->getOperand(Ops[i]).isUse() && "Folding load into def!");
416#endif
417  MachineBasicBlock &MBB = *MI->getParent();
418  MachineFunction &MF = *MBB.getParent();
419
420  // Ask the target to do the actual folding.
421  MachineInstr *NewMI = foldMemoryOperandImpl(MF, MI, Ops, LoadMI);
422  if (!NewMI) return 0;
423
424  NewMI = MBB.insert(MI, NewMI);
425
426  // Copy the memoperands from the load to the folded instruction.
427  NewMI->setMemRefs(LoadMI->memoperands_begin(),
428                    LoadMI->memoperands_end());
429
430  return NewMI;
431}
432
433bool TargetInstrInfo::
434isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
435                                         AliasAnalysis *AA) const {
436  const MachineFunction &MF = *MI->getParent()->getParent();
437  const MachineRegisterInfo &MRI = MF.getRegInfo();
438  const TargetMachine &TM = MF.getTarget();
439  const TargetInstrInfo &TII = *TM.getInstrInfo();
440
441  // Remat clients assume operand 0 is the defined register.
442  if (!MI->getNumOperands() || !MI->getOperand(0).isReg())
443    return false;
444  unsigned DefReg = MI->getOperand(0).getReg();
445
446  // A sub-register definition can only be rematerialized if the instruction
447  // doesn't read the other parts of the register.  Otherwise it is really a
448  // read-modify-write operation on the full virtual register which cannot be
449  // moved safely.
450  if (TargetRegisterInfo::isVirtualRegister(DefReg) &&
451      MI->getOperand(0).getSubReg() && MI->readsVirtualRegister(DefReg))
452    return false;
453
454  // A load from a fixed stack slot can be rematerialized. This may be
455  // redundant with subsequent checks, but it's target-independent,
456  // simple, and a common case.
457  int FrameIdx = 0;
458  if (TII.isLoadFromStackSlot(MI, FrameIdx) &&
459      MF.getFrameInfo()->isImmutableObjectIndex(FrameIdx))
460    return true;
461
462  // Avoid instructions obviously unsafe for remat.
463  if (MI->isNotDuplicable() || MI->mayStore() ||
464      MI->hasUnmodeledSideEffects())
465    return false;
466
467  // Don't remat inline asm. We have no idea how expensive it is
468  // even if it's side effect free.
469  if (MI->isInlineAsm())
470    return false;
471
472  // Avoid instructions which load from potentially varying memory.
473  if (MI->mayLoad() && !MI->isInvariantLoad(AA))
474    return false;
475
476  // If any of the registers accessed are non-constant, conservatively assume
477  // the instruction is not rematerializable.
478  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
479    const MachineOperand &MO = MI->getOperand(i);
480    if (!MO.isReg()) continue;
481    unsigned Reg = MO.getReg();
482    if (Reg == 0)
483      continue;
484
485    // Check for a well-behaved physical register.
486    if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
487      if (MO.isUse()) {
488        // If the physreg has no defs anywhere, it's just an ambient register
489        // and we can freely move its uses. Alternatively, if it's allocatable,
490        // it could get allocated to something with a def during allocation.
491        if (!MRI.isConstantPhysReg(Reg, MF))
492          return false;
493      } else {
494        // A physreg def. We can't remat it.
495        return false;
496      }
497      continue;
498    }
499
500    // Only allow one virtual-register def.  There may be multiple defs of the
501    // same virtual register, though.
502    if (MO.isDef() && Reg != DefReg)
503      return false;
504
505    // Don't allow any virtual-register uses. Rematting an instruction with
506    // virtual register uses would length the live ranges of the uses, which
507    // is not necessarily a good idea, certainly not "trivial".
508    if (MO.isUse())
509      return false;
510  }
511
512  // Everything checked out.
513  return true;
514}
515
516/// isSchedulingBoundary - Test if the given instruction should be
517/// considered a scheduling boundary. This primarily includes labels
518/// and terminators.
519bool TargetInstrInfo::isSchedulingBoundary(const MachineInstr *MI,
520                                           const MachineBasicBlock *MBB,
521                                           const MachineFunction &MF) const {
522  // Terminators and labels can't be scheduled around.
523  if (MI->isTerminator() || MI->isLabel())
524    return true;
525
526  // Don't attempt to schedule around any instruction that defines
527  // a stack-oriented pointer, as it's unlikely to be profitable. This
528  // saves compile time, because it doesn't require every single
529  // stack slot reference to depend on the instruction that does the
530  // modification.
531  const TargetLowering &TLI = *MF.getTarget().getTargetLowering();
532  const TargetRegisterInfo *TRI = MF.getTarget().getRegisterInfo();
533  if (MI->modifiesRegister(TLI.getStackPointerRegisterToSaveRestore(), TRI))
534    return true;
535
536  return false;
537}
538
539// Provide a global flag for disabling the PreRA hazard recognizer that targets
540// may choose to honor.
541bool TargetInstrInfo::usePreRAHazardRecognizer() const {
542  return !DisableHazardRecognizer;
543}
544
545// Default implementation of CreateTargetRAHazardRecognizer.
546ScheduleHazardRecognizer *TargetInstrInfo::
547CreateTargetHazardRecognizer(const TargetMachine *TM,
548                             const ScheduleDAG *DAG) const {
549  // Dummy hazard recognizer allows all instructions to issue.
550  return new ScheduleHazardRecognizer();
551}
552
553// Default implementation of CreateTargetMIHazardRecognizer.
554ScheduleHazardRecognizer *TargetInstrInfo::
555CreateTargetMIHazardRecognizer(const InstrItineraryData *II,
556                               const ScheduleDAG *DAG) const {
557  return (ScheduleHazardRecognizer *)
558    new ScoreboardHazardRecognizer(II, DAG, "misched");
559}
560
561// Default implementation of CreateTargetPostRAHazardRecognizer.
562ScheduleHazardRecognizer *TargetInstrInfo::
563CreateTargetPostRAHazardRecognizer(const InstrItineraryData *II,
564                                   const ScheduleDAG *DAG) const {
565  return (ScheduleHazardRecognizer *)
566    new ScoreboardHazardRecognizer(II, DAG, "post-RA-sched");
567}
568
569//===----------------------------------------------------------------------===//
570//  SelectionDAG latency interface.
571//===----------------------------------------------------------------------===//
572
573int
574TargetInstrInfo::getOperandLatency(const InstrItineraryData *ItinData,
575                                   SDNode *DefNode, unsigned DefIdx,
576                                   SDNode *UseNode, unsigned UseIdx) const {
577  if (!ItinData || ItinData->isEmpty())
578    return -1;
579
580  if (!DefNode->isMachineOpcode())
581    return -1;
582
583  unsigned DefClass = get(DefNode->getMachineOpcode()).getSchedClass();
584  if (!UseNode->isMachineOpcode())
585    return ItinData->getOperandCycle(DefClass, DefIdx);
586  unsigned UseClass = get(UseNode->getMachineOpcode()).getSchedClass();
587  return ItinData->getOperandLatency(DefClass, DefIdx, UseClass, UseIdx);
588}
589
590int TargetInstrInfo::getInstrLatency(const InstrItineraryData *ItinData,
591                                     SDNode *N) const {
592  if (!ItinData || ItinData->isEmpty())
593    return 1;
594
595  if (!N->isMachineOpcode())
596    return 1;
597
598  return ItinData->getStageLatency(get(N->getMachineOpcode()).getSchedClass());
599}
600
601//===----------------------------------------------------------------------===//
602//  MachineInstr latency interface.
603//===----------------------------------------------------------------------===//
604
605unsigned
606TargetInstrInfo::getNumMicroOps(const InstrItineraryData *ItinData,
607                                const MachineInstr *MI) const {
608  if (!ItinData || ItinData->isEmpty())
609    return 1;
610
611  unsigned Class = MI->getDesc().getSchedClass();
612  int UOps = ItinData->Itineraries[Class].NumMicroOps;
613  if (UOps >= 0)
614    return UOps;
615
616  // The # of u-ops is dynamically determined. The specific target should
617  // override this function to return the right number.
618  return 1;
619}
620
621/// Return the default expected latency for a def based on it's opcode.
622unsigned TargetInstrInfo::defaultDefLatency(const MCSchedModel *SchedModel,
623                                            const MachineInstr *DefMI) const {
624  if (DefMI->isTransient())
625    return 0;
626  if (DefMI->mayLoad())
627    return SchedModel->LoadLatency;
628  if (isHighLatencyDef(DefMI->getOpcode()))
629    return SchedModel->HighLatency;
630  return 1;
631}
632
633unsigned TargetInstrInfo::
634getInstrLatency(const InstrItineraryData *ItinData,
635                const MachineInstr *MI,
636                unsigned *PredCost) const {
637  // Default to one cycle for no itinerary. However, an "empty" itinerary may
638  // still have a MinLatency property, which getStageLatency checks.
639  if (!ItinData)
640    return MI->mayLoad() ? 2 : 1;
641
642  return ItinData->getStageLatency(MI->getDesc().getSchedClass());
643}
644
645bool TargetInstrInfo::hasLowDefLatency(const InstrItineraryData *ItinData,
646                                       const MachineInstr *DefMI,
647                                       unsigned DefIdx) const {
648  if (!ItinData || ItinData->isEmpty())
649    return false;
650
651  unsigned DefClass = DefMI->getDesc().getSchedClass();
652  int DefCycle = ItinData->getOperandCycle(DefClass, DefIdx);
653  return (DefCycle != -1 && DefCycle <= 1);
654}
655
656/// Both DefMI and UseMI must be valid.  By default, call directly to the
657/// itinerary. This may be overriden by the target.
658int TargetInstrInfo::
659getOperandLatency(const InstrItineraryData *ItinData,
660                  const MachineInstr *DefMI, unsigned DefIdx,
661                  const MachineInstr *UseMI, unsigned UseIdx) const {
662  unsigned DefClass = DefMI->getDesc().getSchedClass();
663  unsigned UseClass = UseMI->getDesc().getSchedClass();
664  return ItinData->getOperandLatency(DefClass, DefIdx, UseClass, UseIdx);
665}
666
667/// If we can determine the operand latency from the def only, without itinerary
668/// lookup, do so. Otherwise return -1.
669int TargetInstrInfo::computeDefOperandLatency(
670  const InstrItineraryData *ItinData,
671  const MachineInstr *DefMI) const {
672
673  // Let the target hook getInstrLatency handle missing itineraries.
674  if (!ItinData)
675    return getInstrLatency(ItinData, DefMI);
676
677  if(ItinData->isEmpty())
678    return defaultDefLatency(ItinData->SchedModel, DefMI);
679
680  // ...operand lookup required
681  return -1;
682}
683
684/// computeOperandLatency - Compute and return the latency of the given data
685/// dependent def and use when the operand indices are already known. UseMI may
686/// be NULL for an unknown use.
687///
688/// FindMin may be set to get the minimum vs. expected latency. Minimum
689/// latency is used for scheduling groups, while expected latency is for
690/// instruction cost and critical path.
691///
692/// Depending on the subtarget's itinerary properties, this may or may not need
693/// to call getOperandLatency(). For most subtargets, we don't need DefIdx or
694/// UseIdx to compute min latency.
695unsigned TargetInstrInfo::
696computeOperandLatency(const InstrItineraryData *ItinData,
697                      const MachineInstr *DefMI, unsigned DefIdx,
698                      const MachineInstr *UseMI, unsigned UseIdx) const {
699
700  int DefLatency = computeDefOperandLatency(ItinData, DefMI);
701  if (DefLatency >= 0)
702    return DefLatency;
703
704  assert(ItinData && !ItinData->isEmpty() && "computeDefOperandLatency fail");
705
706  int OperLatency = 0;
707  if (UseMI)
708    OperLatency = getOperandLatency(ItinData, DefMI, DefIdx, UseMI, UseIdx);
709  else {
710    unsigned DefClass = DefMI->getDesc().getSchedClass();
711    OperLatency = ItinData->getOperandCycle(DefClass, DefIdx);
712  }
713  if (OperLatency >= 0)
714    return OperLatency;
715
716  // No operand latency was found.
717  unsigned InstrLatency = getInstrLatency(ItinData, DefMI);
718
719  // Expected latency is the max of the stage latency and itinerary props.
720  InstrLatency = std::max(InstrLatency,
721                          defaultDefLatency(ItinData->SchedModel, DefMI));
722  return InstrLatency;
723}
724