1//===-- Instruction.cpp - Implement the Instruction class -----------------===//
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 Instruction class for the IR library.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/IR/Instruction.h"
15#include "llvm/IR/CallSite.h"
16#include "llvm/IR/Constants.h"
17#include "llvm/IR/Instructions.h"
18#include "llvm/IR/Module.h"
19#include "llvm/IR/Operator.h"
20#include "llvm/IR/Type.h"
21using namespace llvm;
22
23Instruction::Instruction(Type *ty, unsigned it, Use *Ops, unsigned NumOps,
24                         Instruction *InsertBefore)
25  : User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(nullptr) {
26
27  // If requested, insert this instruction into a basic block...
28  if (InsertBefore) {
29    BasicBlock *BB = InsertBefore->getParent();
30    assert(BB && "Instruction to insert before is not in a basic block!");
31    BB->getInstList().insert(InsertBefore->getIterator(), this);
32  }
33}
34
35Instruction::Instruction(Type *ty, unsigned it, Use *Ops, unsigned NumOps,
36                         BasicBlock *InsertAtEnd)
37  : User(ty, Value::InstructionVal + it, Ops, NumOps), Parent(nullptr) {
38
39  // append this instruction into the basic block
40  assert(InsertAtEnd && "Basic block to append to may not be NULL!");
41  InsertAtEnd->getInstList().push_back(this);
42}
43
44
45// Out of line virtual method, so the vtable, etc has a home.
46Instruction::~Instruction() {
47  assert(!Parent && "Instruction still linked in the program!");
48  if (hasMetadataHashEntry())
49    clearMetadataHashEntries();
50}
51
52
53void Instruction::setParent(BasicBlock *P) {
54  Parent = P;
55}
56
57const Module *Instruction::getModule() const {
58  return getParent()->getModule();
59}
60
61Module *Instruction::getModule() {
62  return getParent()->getModule();
63}
64
65Function *Instruction::getFunction() { return getParent()->getParent(); }
66
67const Function *Instruction::getFunction() const {
68  return getParent()->getParent();
69}
70
71void Instruction::removeFromParent() {
72  getParent()->getInstList().remove(getIterator());
73}
74
75iplist<Instruction>::iterator Instruction::eraseFromParent() {
76  return getParent()->getInstList().erase(getIterator());
77}
78
79/// Insert an unlinked instruction into a basic block immediately before the
80/// specified instruction.
81void Instruction::insertBefore(Instruction *InsertPos) {
82  InsertPos->getParent()->getInstList().insert(InsertPos->getIterator(), this);
83}
84
85/// Insert an unlinked instruction into a basic block immediately after the
86/// specified instruction.
87void Instruction::insertAfter(Instruction *InsertPos) {
88  InsertPos->getParent()->getInstList().insertAfter(InsertPos->getIterator(),
89                                                    this);
90}
91
92/// Unlink this instruction from its current basic block and insert it into the
93/// basic block that MovePos lives in, right before MovePos.
94void Instruction::moveBefore(Instruction *MovePos) {
95  MovePos->getParent()->getInstList().splice(
96      MovePos->getIterator(), getParent()->getInstList(), getIterator());
97}
98
99void Instruction::setHasNoUnsignedWrap(bool b) {
100  cast<OverflowingBinaryOperator>(this)->setHasNoUnsignedWrap(b);
101}
102
103void Instruction::setHasNoSignedWrap(bool b) {
104  cast<OverflowingBinaryOperator>(this)->setHasNoSignedWrap(b);
105}
106
107void Instruction::setIsExact(bool b) {
108  cast<PossiblyExactOperator>(this)->setIsExact(b);
109}
110
111bool Instruction::hasNoUnsignedWrap() const {
112  return cast<OverflowingBinaryOperator>(this)->hasNoUnsignedWrap();
113}
114
115bool Instruction::hasNoSignedWrap() const {
116  return cast<OverflowingBinaryOperator>(this)->hasNoSignedWrap();
117}
118
119bool Instruction::isExact() const {
120  return cast<PossiblyExactOperator>(this)->isExact();
121}
122
123/// Set or clear the unsafe-algebra flag on this instruction, which must be an
124/// operator which supports this flag. See LangRef.html for the meaning of this
125/// flag.
126void Instruction::setHasUnsafeAlgebra(bool B) {
127  assert(isa<FPMathOperator>(this) && "setting fast-math flag on invalid op");
128  cast<FPMathOperator>(this)->setHasUnsafeAlgebra(B);
129}
130
131/// Set or clear the NoNaNs flag on this instruction, which must be an operator
132/// which supports this flag. See LangRef.html for the meaning of this flag.
133void Instruction::setHasNoNaNs(bool B) {
134  assert(isa<FPMathOperator>(this) && "setting fast-math flag on invalid op");
135  cast<FPMathOperator>(this)->setHasNoNaNs(B);
136}
137
138/// Set or clear the no-infs flag on this instruction, which must be an operator
139/// which supports this flag. See LangRef.html for the meaning of this flag.
140void Instruction::setHasNoInfs(bool B) {
141  assert(isa<FPMathOperator>(this) && "setting fast-math flag on invalid op");
142  cast<FPMathOperator>(this)->setHasNoInfs(B);
143}
144
145/// Set or clear the no-signed-zeros flag on this instruction, which must be an
146/// operator which supports this flag. See LangRef.html for the meaning of this
147/// flag.
148void Instruction::setHasNoSignedZeros(bool B) {
149  assert(isa<FPMathOperator>(this) && "setting fast-math flag on invalid op");
150  cast<FPMathOperator>(this)->setHasNoSignedZeros(B);
151}
152
153/// Set or clear the allow-reciprocal flag on this instruction, which must be an
154/// operator which supports this flag. See LangRef.html for the meaning of this
155/// flag.
156void Instruction::setHasAllowReciprocal(bool B) {
157  assert(isa<FPMathOperator>(this) && "setting fast-math flag on invalid op");
158  cast<FPMathOperator>(this)->setHasAllowReciprocal(B);
159}
160
161/// Convenience function for setting all the fast-math flags on this
162/// instruction, which must be an operator which supports these flags. See
163/// LangRef.html for the meaning of these flats.
164void Instruction::setFastMathFlags(FastMathFlags FMF) {
165  assert(isa<FPMathOperator>(this) && "setting fast-math flag on invalid op");
166  cast<FPMathOperator>(this)->setFastMathFlags(FMF);
167}
168
169void Instruction::copyFastMathFlags(FastMathFlags FMF) {
170  assert(isa<FPMathOperator>(this) && "copying fast-math flag on invalid op");
171  cast<FPMathOperator>(this)->copyFastMathFlags(FMF);
172}
173
174/// Determine whether the unsafe-algebra flag is set.
175bool Instruction::hasUnsafeAlgebra() const {
176  assert(isa<FPMathOperator>(this) && "getting fast-math flag on invalid op");
177  return cast<FPMathOperator>(this)->hasUnsafeAlgebra();
178}
179
180/// Determine whether the no-NaNs flag is set.
181bool Instruction::hasNoNaNs() const {
182  assert(isa<FPMathOperator>(this) && "getting fast-math flag on invalid op");
183  return cast<FPMathOperator>(this)->hasNoNaNs();
184}
185
186/// Determine whether the no-infs flag is set.
187bool Instruction::hasNoInfs() const {
188  assert(isa<FPMathOperator>(this) && "getting fast-math flag on invalid op");
189  return cast<FPMathOperator>(this)->hasNoInfs();
190}
191
192/// Determine whether the no-signed-zeros flag is set.
193bool Instruction::hasNoSignedZeros() const {
194  assert(isa<FPMathOperator>(this) && "getting fast-math flag on invalid op");
195  return cast<FPMathOperator>(this)->hasNoSignedZeros();
196}
197
198/// Determine whether the allow-reciprocal flag is set.
199bool Instruction::hasAllowReciprocal() const {
200  assert(isa<FPMathOperator>(this) && "getting fast-math flag on invalid op");
201  return cast<FPMathOperator>(this)->hasAllowReciprocal();
202}
203
204/// Convenience function for getting all the fast-math flags, which must be an
205/// operator which supports these flags. See LangRef.html for the meaning of
206/// these flags.
207FastMathFlags Instruction::getFastMathFlags() const {
208  assert(isa<FPMathOperator>(this) && "getting fast-math flag on invalid op");
209  return cast<FPMathOperator>(this)->getFastMathFlags();
210}
211
212/// Copy I's fast-math flags
213void Instruction::copyFastMathFlags(const Instruction *I) {
214  copyFastMathFlags(I->getFastMathFlags());
215}
216
217void Instruction::copyIRFlags(const Value *V) {
218  // Copy the wrapping flags.
219  if (auto *OB = dyn_cast<OverflowingBinaryOperator>(V)) {
220    if (isa<OverflowingBinaryOperator>(this)) {
221      setHasNoSignedWrap(OB->hasNoSignedWrap());
222      setHasNoUnsignedWrap(OB->hasNoUnsignedWrap());
223    }
224  }
225
226  // Copy the exact flag.
227  if (auto *PE = dyn_cast<PossiblyExactOperator>(V))
228    if (isa<PossiblyExactOperator>(this))
229      setIsExact(PE->isExact());
230
231  // Copy the fast-math flags.
232  if (auto *FP = dyn_cast<FPMathOperator>(V))
233    if (isa<FPMathOperator>(this))
234      copyFastMathFlags(FP->getFastMathFlags());
235}
236
237void Instruction::andIRFlags(const Value *V) {
238  if (auto *OB = dyn_cast<OverflowingBinaryOperator>(V)) {
239    if (isa<OverflowingBinaryOperator>(this)) {
240      setHasNoSignedWrap(hasNoSignedWrap() & OB->hasNoSignedWrap());
241      setHasNoUnsignedWrap(hasNoUnsignedWrap() & OB->hasNoUnsignedWrap());
242    }
243  }
244
245  if (auto *PE = dyn_cast<PossiblyExactOperator>(V))
246    if (isa<PossiblyExactOperator>(this))
247      setIsExact(isExact() & PE->isExact());
248
249  if (auto *FP = dyn_cast<FPMathOperator>(V)) {
250    if (isa<FPMathOperator>(this)) {
251      FastMathFlags FM = getFastMathFlags();
252      FM &= FP->getFastMathFlags();
253      copyFastMathFlags(FM);
254    }
255  }
256}
257
258const char *Instruction::getOpcodeName(unsigned OpCode) {
259  switch (OpCode) {
260  // Terminators
261  case Ret:    return "ret";
262  case Br:     return "br";
263  case Switch: return "switch";
264  case IndirectBr: return "indirectbr";
265  case Invoke: return "invoke";
266  case Resume: return "resume";
267  case Unreachable: return "unreachable";
268  case CleanupRet: return "cleanupret";
269  case CatchRet: return "catchret";
270  case CatchPad: return "catchpad";
271  case CatchSwitch: return "catchswitch";
272
273  // Standard binary operators...
274  case Add: return "add";
275  case FAdd: return "fadd";
276  case Sub: return "sub";
277  case FSub: return "fsub";
278  case Mul: return "mul";
279  case FMul: return "fmul";
280  case UDiv: return "udiv";
281  case SDiv: return "sdiv";
282  case FDiv: return "fdiv";
283  case URem: return "urem";
284  case SRem: return "srem";
285  case FRem: return "frem";
286
287  // Logical operators...
288  case And: return "and";
289  case Or : return "or";
290  case Xor: return "xor";
291
292  // Memory instructions...
293  case Alloca:        return "alloca";
294  case Load:          return "load";
295  case Store:         return "store";
296  case AtomicCmpXchg: return "cmpxchg";
297  case AtomicRMW:     return "atomicrmw";
298  case Fence:         return "fence";
299  case GetElementPtr: return "getelementptr";
300
301  // Convert instructions...
302  case Trunc:         return "trunc";
303  case ZExt:          return "zext";
304  case SExt:          return "sext";
305  case FPTrunc:       return "fptrunc";
306  case FPExt:         return "fpext";
307  case FPToUI:        return "fptoui";
308  case FPToSI:        return "fptosi";
309  case UIToFP:        return "uitofp";
310  case SIToFP:        return "sitofp";
311  case IntToPtr:      return "inttoptr";
312  case PtrToInt:      return "ptrtoint";
313  case BitCast:       return "bitcast";
314  case AddrSpaceCast: return "addrspacecast";
315
316  // Other instructions...
317  case ICmp:           return "icmp";
318  case FCmp:           return "fcmp";
319  case PHI:            return "phi";
320  case Select:         return "select";
321  case Call:           return "call";
322  case Shl:            return "shl";
323  case LShr:           return "lshr";
324  case AShr:           return "ashr";
325  case VAArg:          return "va_arg";
326  case ExtractElement: return "extractelement";
327  case InsertElement:  return "insertelement";
328  case ShuffleVector:  return "shufflevector";
329  case ExtractValue:   return "extractvalue";
330  case InsertValue:    return "insertvalue";
331  case LandingPad:     return "landingpad";
332  case CleanupPad:     return "cleanuppad";
333
334  default: return "<Invalid operator> ";
335  }
336}
337
338/// Return true if both instructions have the same special state This must be
339/// kept in sync with FunctionComparator::cmpOperations in
340/// lib/Transforms/IPO/MergeFunctions.cpp.
341static bool haveSameSpecialState(const Instruction *I1, const Instruction *I2,
342                                 bool IgnoreAlignment = false) {
343  assert(I1->getOpcode() == I2->getOpcode() &&
344         "Can not compare special state of different instructions");
345
346  if (const AllocaInst *AI = dyn_cast<AllocaInst>(I1))
347    return AI->getAllocatedType() == cast<AllocaInst>(I2)->getAllocatedType() &&
348           (AI->getAlignment() == cast<AllocaInst>(I2)->getAlignment() ||
349            IgnoreAlignment);
350  if (const LoadInst *LI = dyn_cast<LoadInst>(I1))
351    return LI->isVolatile() == cast<LoadInst>(I2)->isVolatile() &&
352           (LI->getAlignment() == cast<LoadInst>(I2)->getAlignment() ||
353            IgnoreAlignment) &&
354           LI->getOrdering() == cast<LoadInst>(I2)->getOrdering() &&
355           LI->getSynchScope() == cast<LoadInst>(I2)->getSynchScope();
356  if (const StoreInst *SI = dyn_cast<StoreInst>(I1))
357    return SI->isVolatile() == cast<StoreInst>(I2)->isVolatile() &&
358           (SI->getAlignment() == cast<StoreInst>(I2)->getAlignment() ||
359            IgnoreAlignment) &&
360           SI->getOrdering() == cast<StoreInst>(I2)->getOrdering() &&
361           SI->getSynchScope() == cast<StoreInst>(I2)->getSynchScope();
362  if (const CmpInst *CI = dyn_cast<CmpInst>(I1))
363    return CI->getPredicate() == cast<CmpInst>(I2)->getPredicate();
364  if (const CallInst *CI = dyn_cast<CallInst>(I1))
365    return CI->isTailCall() == cast<CallInst>(I2)->isTailCall() &&
366           CI->getCallingConv() == cast<CallInst>(I2)->getCallingConv() &&
367           CI->getAttributes() == cast<CallInst>(I2)->getAttributes() &&
368           CI->hasIdenticalOperandBundleSchema(*cast<CallInst>(I2));
369  if (const InvokeInst *CI = dyn_cast<InvokeInst>(I1))
370    return CI->getCallingConv() == cast<InvokeInst>(I2)->getCallingConv() &&
371           CI->getAttributes() == cast<InvokeInst>(I2)->getAttributes() &&
372           CI->hasIdenticalOperandBundleSchema(*cast<InvokeInst>(I2));
373  if (const InsertValueInst *IVI = dyn_cast<InsertValueInst>(I1))
374    return IVI->getIndices() == cast<InsertValueInst>(I2)->getIndices();
375  if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(I1))
376    return EVI->getIndices() == cast<ExtractValueInst>(I2)->getIndices();
377  if (const FenceInst *FI = dyn_cast<FenceInst>(I1))
378    return FI->getOrdering() == cast<FenceInst>(I2)->getOrdering() &&
379           FI->getSynchScope() == cast<FenceInst>(I2)->getSynchScope();
380  if (const AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(I1))
381    return CXI->isVolatile() == cast<AtomicCmpXchgInst>(I2)->isVolatile() &&
382           CXI->isWeak() == cast<AtomicCmpXchgInst>(I2)->isWeak() &&
383           CXI->getSuccessOrdering() ==
384               cast<AtomicCmpXchgInst>(I2)->getSuccessOrdering() &&
385           CXI->getFailureOrdering() ==
386               cast<AtomicCmpXchgInst>(I2)->getFailureOrdering() &&
387           CXI->getSynchScope() == cast<AtomicCmpXchgInst>(I2)->getSynchScope();
388  if (const AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I1))
389    return RMWI->getOperation() == cast<AtomicRMWInst>(I2)->getOperation() &&
390           RMWI->isVolatile() == cast<AtomicRMWInst>(I2)->isVolatile() &&
391           RMWI->getOrdering() == cast<AtomicRMWInst>(I2)->getOrdering() &&
392           RMWI->getSynchScope() == cast<AtomicRMWInst>(I2)->getSynchScope();
393
394  return true;
395}
396
397/// isIdenticalTo - Return true if the specified instruction is exactly
398/// identical to the current one.  This means that all operands match and any
399/// extra information (e.g. load is volatile) agree.
400bool Instruction::isIdenticalTo(const Instruction *I) const {
401  return isIdenticalToWhenDefined(I) &&
402         SubclassOptionalData == I->SubclassOptionalData;
403}
404
405/// isIdenticalToWhenDefined - This is like isIdenticalTo, except that it
406/// ignores the SubclassOptionalData flags, which specify conditions
407/// under which the instruction's result is undefined.
408bool Instruction::isIdenticalToWhenDefined(const Instruction *I) const {
409  if (getOpcode() != I->getOpcode() ||
410      getNumOperands() != I->getNumOperands() ||
411      getType() != I->getType())
412    return false;
413
414  // If both instructions have no operands, they are identical.
415  if (getNumOperands() == 0 && I->getNumOperands() == 0)
416    return haveSameSpecialState(this, I);
417
418  // We have two instructions of identical opcode and #operands.  Check to see
419  // if all operands are the same.
420  if (!std::equal(op_begin(), op_end(), I->op_begin()))
421    return false;
422
423  if (const PHINode *thisPHI = dyn_cast<PHINode>(this)) {
424    const PHINode *otherPHI = cast<PHINode>(I);
425    return std::equal(thisPHI->block_begin(), thisPHI->block_end(),
426                      otherPHI->block_begin());
427  }
428
429  return haveSameSpecialState(this, I);
430}
431
432// Keep this in sync with FunctionComparator::cmpOperations in
433// lib/Transforms/IPO/MergeFunctions.cpp.
434bool Instruction::isSameOperationAs(const Instruction *I,
435                                    unsigned flags) const {
436  bool IgnoreAlignment = flags & CompareIgnoringAlignment;
437  bool UseScalarTypes  = flags & CompareUsingScalarTypes;
438
439  if (getOpcode() != I->getOpcode() ||
440      getNumOperands() != I->getNumOperands() ||
441      (UseScalarTypes ?
442       getType()->getScalarType() != I->getType()->getScalarType() :
443       getType() != I->getType()))
444    return false;
445
446  // We have two instructions of identical opcode and #operands.  Check to see
447  // if all operands are the same type
448  for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
449    if (UseScalarTypes ?
450        getOperand(i)->getType()->getScalarType() !=
451          I->getOperand(i)->getType()->getScalarType() :
452        getOperand(i)->getType() != I->getOperand(i)->getType())
453      return false;
454
455  return haveSameSpecialState(this, I, IgnoreAlignment);
456}
457
458/// isUsedOutsideOfBlock - Return true if there are any uses of I outside of the
459/// specified block.  Note that PHI nodes are considered to evaluate their
460/// operands in the corresponding predecessor block.
461bool Instruction::isUsedOutsideOfBlock(const BasicBlock *BB) const {
462  for (const Use &U : uses()) {
463    // PHI nodes uses values in the corresponding predecessor block.  For other
464    // instructions, just check to see whether the parent of the use matches up.
465    const Instruction *I = cast<Instruction>(U.getUser());
466    const PHINode *PN = dyn_cast<PHINode>(I);
467    if (!PN) {
468      if (I->getParent() != BB)
469        return true;
470      continue;
471    }
472
473    if (PN->getIncomingBlock(U) != BB)
474      return true;
475  }
476  return false;
477}
478
479/// mayReadFromMemory - Return true if this instruction may read memory.
480///
481bool Instruction::mayReadFromMemory() const {
482  switch (getOpcode()) {
483  default: return false;
484  case Instruction::VAArg:
485  case Instruction::Load:
486  case Instruction::Fence: // FIXME: refine definition of mayReadFromMemory
487  case Instruction::AtomicCmpXchg:
488  case Instruction::AtomicRMW:
489  case Instruction::CatchPad:
490  case Instruction::CatchRet:
491    return true;
492  case Instruction::Call:
493    return !cast<CallInst>(this)->doesNotAccessMemory();
494  case Instruction::Invoke:
495    return !cast<InvokeInst>(this)->doesNotAccessMemory();
496  case Instruction::Store:
497    return !cast<StoreInst>(this)->isUnordered();
498  }
499}
500
501/// mayWriteToMemory - Return true if this instruction may modify memory.
502///
503bool Instruction::mayWriteToMemory() const {
504  switch (getOpcode()) {
505  default: return false;
506  case Instruction::Fence: // FIXME: refine definition of mayWriteToMemory
507  case Instruction::Store:
508  case Instruction::VAArg:
509  case Instruction::AtomicCmpXchg:
510  case Instruction::AtomicRMW:
511  case Instruction::CatchPad:
512  case Instruction::CatchRet:
513    return true;
514  case Instruction::Call:
515    return !cast<CallInst>(this)->onlyReadsMemory();
516  case Instruction::Invoke:
517    return !cast<InvokeInst>(this)->onlyReadsMemory();
518  case Instruction::Load:
519    return !cast<LoadInst>(this)->isUnordered();
520  }
521}
522
523bool Instruction::isAtomic() const {
524  switch (getOpcode()) {
525  default:
526    return false;
527  case Instruction::AtomicCmpXchg:
528  case Instruction::AtomicRMW:
529  case Instruction::Fence:
530    return true;
531  case Instruction::Load:
532    return cast<LoadInst>(this)->getOrdering() != AtomicOrdering::NotAtomic;
533  case Instruction::Store:
534    return cast<StoreInst>(this)->getOrdering() != AtomicOrdering::NotAtomic;
535  }
536}
537
538bool Instruction::mayThrow() const {
539  if (const CallInst *CI = dyn_cast<CallInst>(this))
540    return !CI->doesNotThrow();
541  if (const auto *CRI = dyn_cast<CleanupReturnInst>(this))
542    return CRI->unwindsToCaller();
543  if (const auto *CatchSwitch = dyn_cast<CatchSwitchInst>(this))
544    return CatchSwitch->unwindsToCaller();
545  return isa<ResumeInst>(this);
546}
547
548/// isAssociative - Return true if the instruction is associative:
549///
550///   Associative operators satisfy:  x op (y op z) === (x op y) op z
551///
552/// In LLVM, the Add, Mul, And, Or, and Xor operators are associative.
553///
554bool Instruction::isAssociative(unsigned Opcode) {
555  return Opcode == And || Opcode == Or || Opcode == Xor ||
556         Opcode == Add || Opcode == Mul;
557}
558
559bool Instruction::isAssociative() const {
560  unsigned Opcode = getOpcode();
561  if (isAssociative(Opcode))
562    return true;
563
564  switch (Opcode) {
565  case FMul:
566  case FAdd:
567    return cast<FPMathOperator>(this)->hasUnsafeAlgebra();
568  default:
569    return false;
570  }
571}
572
573/// isCommutative - Return true if the instruction is commutative:
574///
575///   Commutative operators satisfy: (x op y) === (y op x)
576///
577/// In LLVM, these are the associative operators, plus SetEQ and SetNE, when
578/// applied to any type.
579///
580bool Instruction::isCommutative(unsigned op) {
581  switch (op) {
582  case Add:
583  case FAdd:
584  case Mul:
585  case FMul:
586  case And:
587  case Or:
588  case Xor:
589    return true;
590  default:
591    return false;
592  }
593}
594
595/// isIdempotent - Return true if the instruction is idempotent:
596///
597///   Idempotent operators satisfy:  x op x === x
598///
599/// In LLVM, the And and Or operators are idempotent.
600///
601bool Instruction::isIdempotent(unsigned Opcode) {
602  return Opcode == And || Opcode == Or;
603}
604
605/// isNilpotent - Return true if the instruction is nilpotent:
606///
607///   Nilpotent operators satisfy:  x op x === Id,
608///
609///   where Id is the identity for the operator, i.e. a constant such that
610///     x op Id === x and Id op x === x for all x.
611///
612/// In LLVM, the Xor operator is nilpotent.
613///
614bool Instruction::isNilpotent(unsigned Opcode) {
615  return Opcode == Xor;
616}
617
618Instruction *Instruction::cloneImpl() const {
619  llvm_unreachable("Subclass of Instruction failed to implement cloneImpl");
620}
621
622Instruction *Instruction::clone() const {
623  Instruction *New = nullptr;
624  switch (getOpcode()) {
625  default:
626    llvm_unreachable("Unhandled Opcode.");
627#define HANDLE_INST(num, opc, clas)                                            \
628  case Instruction::opc:                                                       \
629    New = cast<clas>(this)->cloneImpl();                                       \
630    break;
631#include "llvm/IR/Instruction.def"
632#undef HANDLE_INST
633  }
634
635  New->SubclassOptionalData = SubclassOptionalData;
636  if (!hasMetadata())
637    return New;
638
639  // Otherwise, enumerate and copy over metadata from the old instruction to the
640  // new one.
641  SmallVector<std::pair<unsigned, MDNode *>, 4> TheMDs;
642  getAllMetadataOtherThanDebugLoc(TheMDs);
643  for (const auto &MD : TheMDs)
644    New->setMetadata(MD.first, MD.second);
645
646  New->setDebugLoc(getDebugLoc());
647  return New;
648}
649