LLVM  3.7.0
PHITransAddr.cpp
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1 //===- PHITransAddr.cpp - PHI Translation for Addresses -------------------===//
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 PHITransAddr class.
11 //
12 //===----------------------------------------------------------------------===//
13 
17 #include "llvm/IR/Constants.h"
18 #include "llvm/IR/Dominators.h"
19 #include "llvm/IR/Instructions.h"
20 #include "llvm/Support/Debug.h"
23 using namespace llvm;
24 
25 static bool CanPHITrans(Instruction *Inst) {
26  if (isa<PHINode>(Inst) ||
27  isa<GetElementPtrInst>(Inst))
28  return true;
29 
30  if (isa<CastInst>(Inst) &&
32  return true;
33 
34  if (Inst->getOpcode() == Instruction::Add &&
35  isa<ConstantInt>(Inst->getOperand(1)))
36  return true;
37 
38  // cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
39  // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst))
40  // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0);
41  return false;
42 }
43 
44 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
45 void PHITransAddr::dump() const {
46  if (!Addr) {
47  dbgs() << "PHITransAddr: null\n";
48  return;
49  }
50  dbgs() << "PHITransAddr: " << *Addr << "\n";
51  for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)
52  dbgs() << " Input #" << i << " is " << *InstInputs[i] << "\n";
53 }
54 #endif
55 
56 
57 static bool VerifySubExpr(Value *Expr,
58  SmallVectorImpl<Instruction*> &InstInputs) {
59  // If this is a non-instruction value, there is nothing to do.
61  if (!I) return true;
62 
63  // If it's an instruction, it is either in Tmp or its operands recursively
64  // are.
66  std::find(InstInputs.begin(), InstInputs.end(), I);
67  if (Entry != InstInputs.end()) {
68  InstInputs.erase(Entry);
69  return true;
70  }
71 
72  // If it isn't in the InstInputs list it is a subexpr incorporated into the
73  // address. Sanity check that it is phi translatable.
74  if (!CanPHITrans(I)) {
75  errs() << "Instruction in PHITransAddr is not phi-translatable:\n";
76  errs() << *I << '\n';
77  llvm_unreachable("Either something is missing from InstInputs or "
78  "CanPHITrans is wrong.");
79  }
80 
81  // Validate the operands of the instruction.
82  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
83  if (!VerifySubExpr(I->getOperand(i), InstInputs))
84  return false;
85 
86  return true;
87 }
88 
89 /// Verify - Check internal consistency of this data structure. If the
90 /// structure is valid, it returns true. If invalid, it prints errors and
91 /// returns false.
92 bool PHITransAddr::Verify() const {
93  if (!Addr) return true;
94 
95  SmallVector<Instruction*, 8> Tmp(InstInputs.begin(), InstInputs.end());
96 
97  if (!VerifySubExpr(Addr, Tmp))
98  return false;
99 
100  if (!Tmp.empty()) {
101  errs() << "PHITransAddr contains extra instructions:\n";
102  for (unsigned i = 0, e = InstInputs.size(); i != e; ++i)
103  errs() << " InstInput #" << i << " is " << *InstInputs[i] << "\n";
104  llvm_unreachable("This is unexpected.");
105  }
106 
107  // a-ok.
108  return true;
109 }
110 
111 
112 /// IsPotentiallyPHITranslatable - If this needs PHI translation, return true
113 /// if we have some hope of doing it. This should be used as a filter to
114 /// avoid calling PHITranslateValue in hopeless situations.
116  // If the input value is not an instruction, or if it is not defined in CurBB,
117  // then we don't need to phi translate it.
118  Instruction *Inst = dyn_cast<Instruction>(Addr);
119  return !Inst || CanPHITrans(Inst);
120 }
121 
122 
123 static void RemoveInstInputs(Value *V,
124  SmallVectorImpl<Instruction*> &InstInputs) {
126  if (!I) return;
127 
128  // If the instruction is in the InstInputs list, remove it.
130  std::find(InstInputs.begin(), InstInputs.end(), I);
131  if (Entry != InstInputs.end()) {
132  InstInputs.erase(Entry);
133  return;
134  }
135 
136  assert(!isa<PHINode>(I) && "Error, removing something that isn't an input");
137 
138  // Otherwise, it must have instruction inputs itself. Zap them recursively.
139  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
140  if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
141  RemoveInstInputs(Op, InstInputs);
142  }
143 }
144 
145 Value *PHITransAddr::PHITranslateSubExpr(Value *V, BasicBlock *CurBB,
146  BasicBlock *PredBB,
147  const DominatorTree *DT) {
148  // If this is a non-instruction value, it can't require PHI translation.
149  Instruction *Inst = dyn_cast<Instruction>(V);
150  if (!Inst) return V;
151 
152  // Determine whether 'Inst' is an input to our PHI translatable expression.
153  bool isInput =
154  std::find(InstInputs.begin(), InstInputs.end(), Inst) != InstInputs.end();
155 
156  // Handle inputs instructions if needed.
157  if (isInput) {
158  if (Inst->getParent() != CurBB) {
159  // If it is an input defined in a different block, then it remains an
160  // input.
161  return Inst;
162  }
163 
164  // If 'Inst' is defined in this block and is an input that needs to be phi
165  // translated, we need to incorporate the value into the expression or fail.
166 
167  // In either case, the instruction itself isn't an input any longer.
168  InstInputs.erase(std::find(InstInputs.begin(), InstInputs.end(), Inst));
169 
170  // If this is a PHI, go ahead and translate it.
171  if (PHINode *PN = dyn_cast<PHINode>(Inst))
172  return AddAsInput(PN->getIncomingValueForBlock(PredBB));
173 
174  // If this is a non-phi value, and it is analyzable, we can incorporate it
175  // into the expression by making all instruction operands be inputs.
176  if (!CanPHITrans(Inst))
177  return nullptr;
178 
179  // All instruction operands are now inputs (and of course, they may also be
180  // defined in this block, so they may need to be phi translated themselves.
181  for (unsigned i = 0, e = Inst->getNumOperands(); i != e; ++i)
182  if (Instruction *Op = dyn_cast<Instruction>(Inst->getOperand(i)))
183  InstInputs.push_back(Op);
184  }
185 
186  // Ok, it must be an intermediate result (either because it started that way
187  // or because we just incorporated it into the expression). See if its
188  // operands need to be phi translated, and if so, reconstruct it.
189 
190  if (CastInst *Cast = dyn_cast<CastInst>(Inst)) {
191  if (!isSafeToSpeculativelyExecute(Cast)) return nullptr;
192  Value *PHIIn = PHITranslateSubExpr(Cast->getOperand(0), CurBB, PredBB, DT);
193  if (!PHIIn) return nullptr;
194  if (PHIIn == Cast->getOperand(0))
195  return Cast;
196 
197  // Find an available version of this cast.
198 
199  // Constants are trivial to find.
200  if (Constant *C = dyn_cast<Constant>(PHIIn))
201  return AddAsInput(ConstantExpr::getCast(Cast->getOpcode(),
202  C, Cast->getType()));
203 
204  // Otherwise we have to see if a casted version of the incoming pointer
205  // is available. If so, we can use it, otherwise we have to fail.
206  for (User *U : PHIIn->users()) {
207  if (CastInst *CastI = dyn_cast<CastInst>(U))
208  if (CastI->getOpcode() == Cast->getOpcode() &&
209  CastI->getType() == Cast->getType() &&
210  (!DT || DT->dominates(CastI->getParent(), PredBB)))
211  return CastI;
212  }
213  return nullptr;
214  }
215 
216  // Handle getelementptr with at least one PHI translatable operand.
217  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
218  SmallVector<Value*, 8> GEPOps;
219  bool AnyChanged = false;
220  for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
221  Value *GEPOp = PHITranslateSubExpr(GEP->getOperand(i), CurBB, PredBB, DT);
222  if (!GEPOp) return nullptr;
223 
224  AnyChanged |= GEPOp != GEP->getOperand(i);
225  GEPOps.push_back(GEPOp);
226  }
227 
228  if (!AnyChanged)
229  return GEP;
230 
231  // Simplify the GEP to handle 'gep x, 0' -> x etc.
232  if (Value *V = SimplifyGEPInst(GEPOps, DL, TLI, DT, AC)) {
233  for (unsigned i = 0, e = GEPOps.size(); i != e; ++i)
234  RemoveInstInputs(GEPOps[i], InstInputs);
235 
236  return AddAsInput(V);
237  }
238 
239  // Scan to see if we have this GEP available.
240  Value *APHIOp = GEPOps[0];
241  for (User *U : APHIOp->users()) {
242  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(U))
243  if (GEPI->getType() == GEP->getType() &&
244  GEPI->getNumOperands() == GEPOps.size() &&
245  GEPI->getParent()->getParent() == CurBB->getParent() &&
246  (!DT || DT->dominates(GEPI->getParent(), PredBB))) {
247  if (std::equal(GEPOps.begin(), GEPOps.end(), GEPI->op_begin()))
248  return GEPI;
249  }
250  }
251  return nullptr;
252  }
253 
254  // Handle add with a constant RHS.
255  if (Inst->getOpcode() == Instruction::Add &&
256  isa<ConstantInt>(Inst->getOperand(1))) {
257  // PHI translate the LHS.
258  Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
259  bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
260  bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
261 
262  Value *LHS = PHITranslateSubExpr(Inst->getOperand(0), CurBB, PredBB, DT);
263  if (!LHS) return nullptr;
264 
265  // If the PHI translated LHS is an add of a constant, fold the immediates.
266  if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
267  if (BOp->getOpcode() == Instruction::Add)
268  if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
269  LHS = BOp->getOperand(0);
270  RHS = ConstantExpr::getAdd(RHS, CI);
271  isNSW = isNUW = false;
272 
273  // If the old 'LHS' was an input, add the new 'LHS' as an input.
274  if (std::find(InstInputs.begin(), InstInputs.end(), BOp) !=
275  InstInputs.end()) {
276  RemoveInstInputs(BOp, InstInputs);
277  AddAsInput(LHS);
278  }
279  }
280 
281  // See if the add simplifies away.
282  if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, DL, TLI, DT, AC)) {
283  // If we simplified the operands, the LHS is no longer an input, but Res
284  // is.
285  RemoveInstInputs(LHS, InstInputs);
286  return AddAsInput(Res);
287  }
288 
289  // If we didn't modify the add, just return it.
290  if (LHS == Inst->getOperand(0) && RHS == Inst->getOperand(1))
291  return Inst;
292 
293  // Otherwise, see if we have this add available somewhere.
294  for (User *U : LHS->users()) {
295  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U))
296  if (BO->getOpcode() == Instruction::Add &&
297  BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
298  BO->getParent()->getParent() == CurBB->getParent() &&
299  (!DT || DT->dominates(BO->getParent(), PredBB)))
300  return BO;
301  }
302 
303  return nullptr;
304  }
305 
306  // Otherwise, we failed.
307  return nullptr;
308 }
309 
310 
311 /// PHITranslateValue - PHI translate the current address up the CFG from
312 /// CurBB to Pred, updating our state to reflect any needed changes. If
313 /// 'MustDominate' is true, the translated value must dominate
314 /// PredBB. This returns true on failure and sets Addr to null.
316  const DominatorTree *DT,
317  bool MustDominate) {
318  assert(DT || !MustDominate);
319  assert(Verify() && "Invalid PHITransAddr!");
320  if (DT && DT->isReachableFromEntry(PredBB))
321  Addr =
322  PHITranslateSubExpr(Addr, CurBB, PredBB, MustDominate ? DT : nullptr);
323  else
324  Addr = nullptr;
325  assert(Verify() && "Invalid PHITransAddr!");
326 
327  if (MustDominate)
328  // Make sure the value is live in the predecessor.
329  if (Instruction *Inst = dyn_cast_or_null<Instruction>(Addr))
330  if (!DT->dominates(Inst->getParent(), PredBB))
331  Addr = nullptr;
332 
333  return Addr == nullptr;
334 }
335 
336 /// PHITranslateWithInsertion - PHI translate this value into the specified
337 /// predecessor block, inserting a computation of the value if it is
338 /// unavailable.
339 ///
340 /// All newly created instructions are added to the NewInsts list. This
341 /// returns null on failure.
342 ///
345  const DominatorTree &DT,
346  SmallVectorImpl<Instruction*> &NewInsts) {
347  unsigned NISize = NewInsts.size();
348 
349  // Attempt to PHI translate with insertion.
350  Addr = InsertPHITranslatedSubExpr(Addr, CurBB, PredBB, DT, NewInsts);
351 
352  // If successful, return the new value.
353  if (Addr) return Addr;
354 
355  // If not, destroy any intermediate instructions inserted.
356  while (NewInsts.size() != NISize)
357  NewInsts.pop_back_val()->eraseFromParent();
358  return nullptr;
359 }
360 
361 
362 /// InsertPHITranslatedPointer - Insert a computation of the PHI translated
363 /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB
364 /// block. All newly created instructions are added to the NewInsts list.
365 /// This returns null on failure.
366 ///
367 Value *PHITransAddr::
368 InsertPHITranslatedSubExpr(Value *InVal, BasicBlock *CurBB,
369  BasicBlock *PredBB, const DominatorTree &DT,
370  SmallVectorImpl<Instruction*> &NewInsts) {
371  // See if we have a version of this value already available and dominating
372  // PredBB. If so, there is no need to insert a new instance of it.
373  PHITransAddr Tmp(InVal, DL, AC);
374  if (!Tmp.PHITranslateValue(CurBB, PredBB, &DT, /*MustDominate=*/true))
375  return Tmp.getAddr();
376 
377  // We don't need to PHI translate values which aren't instructions.
378  auto *Inst = dyn_cast<Instruction>(InVal);
379  if (!Inst)
380  return nullptr;
381 
382  // Handle cast of PHI translatable value.
383  if (CastInst *Cast = dyn_cast<CastInst>(Inst)) {
384  if (!isSafeToSpeculativelyExecute(Cast)) return nullptr;
385  Value *OpVal = InsertPHITranslatedSubExpr(Cast->getOperand(0),
386  CurBB, PredBB, DT, NewInsts);
387  if (!OpVal) return nullptr;
388 
389  // Otherwise insert a cast at the end of PredBB.
390  CastInst *New = CastInst::Create(Cast->getOpcode(), OpVal, InVal->getType(),
391  InVal->getName() + ".phi.trans.insert",
392  PredBB->getTerminator());
393  New->setDebugLoc(Inst->getDebugLoc());
394  NewInsts.push_back(New);
395  return New;
396  }
397 
398  // Handle getelementptr with at least one PHI operand.
399  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
400  SmallVector<Value*, 8> GEPOps;
401  BasicBlock *CurBB = GEP->getParent();
402  for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
403  Value *OpVal = InsertPHITranslatedSubExpr(GEP->getOperand(i),
404  CurBB, PredBB, DT, NewInsts);
405  if (!OpVal) return nullptr;
406  GEPOps.push_back(OpVal);
407  }
408 
410  GEP->getSourceElementType(), GEPOps[0], makeArrayRef(GEPOps).slice(1),
411  InVal->getName() + ".phi.trans.insert", PredBB->getTerminator());
412  Result->setDebugLoc(Inst->getDebugLoc());
413  Result->setIsInBounds(GEP->isInBounds());
414  NewInsts.push_back(Result);
415  return Result;
416  }
417 
418 #if 0
419  // FIXME: This code works, but it is unclear that we actually want to insert
420  // a big chain of computation in order to make a value available in a block.
421  // This needs to be evaluated carefully to consider its cost trade offs.
422 
423  // Handle add with a constant RHS.
424  if (Inst->getOpcode() == Instruction::Add &&
425  isa<ConstantInt>(Inst->getOperand(1))) {
426  // PHI translate the LHS.
427  Value *OpVal = InsertPHITranslatedSubExpr(Inst->getOperand(0),
428  CurBB, PredBB, DT, NewInsts);
429  if (OpVal == 0) return 0;
430 
431  BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1),
432  InVal->getName()+".phi.trans.insert",
433  PredBB->getTerminator());
434  Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap());
435  Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap());
436  NewInsts.push_back(Res);
437  return Res;
438  }
439 #endif
440 
441  return nullptr;
442 }
iplist< Instruction >::iterator eraseFromParent()
eraseFromParent - This method unlinks 'this' from the containing basic block and deletes it...
Definition: Instruction.cpp:70
void setHasNoSignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag...
raw_ostream & errs()
This returns a reference to a raw_ostream for standard error.
Value * PHITranslateWithInsertion(BasicBlock *CurBB, BasicBlock *PredBB, const DominatorTree &DT, SmallVectorImpl< Instruction * > &NewInsts)
PHITranslateWithInsertion - PHI translate this value into the specified predecessor block...
unsigned getNumOperands() const
Definition: User.h:138
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:111
Hexagon Common GEP
Value * SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr)
SimplifyAddInst - Given operands for an Add, see if we can fold the result.
StringRef getName() const
Return a constant reference to the value's name.
Definition: Value.cpp:188
static Constant * getAdd(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2258
static bool isInput(const llvm::StringSet<> &Prefixes, StringRef Arg)
Definition: OptTable.cpp:164
This is the base class for all instructions that perform data casts.
Definition: InstrTypes.h:389
ArrayRef< T > makeArrayRef(const T &OneElt)
Construct an ArrayRef from a single element.
Definition: ArrayRef.h:308
T LLVM_ATTRIBUTE_UNUSED_RESULT pop_back_val()
Definition: SmallVector.h:406
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
void setHasNoUnsignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag...
void setIsInBounds(bool b=true)
setIsInBounds - Set or clear the inbounds flag on this GEP instruction.
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APInt.h:33
void dump() const
bool isReachableFromEntry(const Use &U) const
Provide an overload for a Use.
Definition: Dominators.cpp:265
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:67
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
GetElementPtrInst - an instruction for type-safe pointer arithmetic to access elements of arrays and ...
Definition: Instructions.h:830
void setDebugLoc(DebugLoc Loc)
setDebugLoc - Set the debug location information for this instruction.
Definition: Instruction.h:227
LLVM Basic Block Representation.
Definition: BasicBlock.h:65
PHITransAddr - An address value which tracks and handles phi translation.
Definition: PHITransAddr.h:36
This is an important base class in LLVM.
Definition: Constant.h:41
This file contains the declarations for the subclasses of Constant, which represent the different fla...
const DebugLoc & getDebugLoc() const
getDebugLoc - Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:230
Value * getOperand(unsigned i) const
Definition: User.h:118
iterator erase(iterator I)
Definition: SmallVector.h:455
static GetElementPtrInst * Create(Type *PointeeType, Value *Ptr, ArrayRef< Value * > IdxList, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Definition: Instructions.h:854
bool IsPotentiallyPHITranslatable() const
IsPotentiallyPHITranslatable - If this needs PHI translation, return true if we have some hope of doi...
static void RemoveInstInputs(Value *V, SmallVectorImpl< Instruction * > &InstInputs)
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:214
This is the shared class of boolean and integer constants.
Definition: Constants.h:47
bool PHITranslateValue(BasicBlock *CurBB, BasicBlock *PredBB, const DominatorTree *DT, bool MustDominate)
PHITranslateValue - PHI translate the current address up the CFG from CurBB to Pred, updating our state to reflect any needed changes.
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:222
static bool VerifySubExpr(Value *Expr, SmallVectorImpl< Instruction * > &InstInputs)
Value * SimplifyGEPInst(ArrayRef< Value * > Ops, const DataLayout &DL, const TargetLibraryInfo *TLI=nullptr, const DominatorTree *DT=nullptr, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr)
SimplifyGEPInst - Given operands for an GetElementPtrInst, see if we can fold the result...
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
iterator_range< user_iterator > users()
Definition: Value.h:300
static Constant * getCast(unsigned ops, Constant *C, Type *Ty, bool OnlyIfReduced=false)
Convenience function for getting a Cast operation.
Definition: Constants.cpp:1591
LLVM_ATTRIBUTE_UNUSED_RESULT std::enable_if< !is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:285
static bool CanPHITrans(Instruction *Inst)
static CastInst * Create(Instruction::CastOps, Value *S, Type *Ty, const Twine &Name="", Instruction *InsertBefore=nullptr)
Provides a way to construct any of the CastInst subclasses using an opcode instead of the subclass's ...
#define I(x, y, z)
Definition: MD5.cpp:54
LLVM Value Representation.
Definition: Value.h:69
unsigned getOpcode() const
getOpcode() returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:112
bool isSafeToSpeculativelyExecute(const Value *V, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr, const TargetLibraryInfo *TLI=nullptr)
isSafeToSpeculativelyExecute - Return true if the instruction does not have any effects besides calcu...
bool Verify() const
Verify - Check internal consistency of this data structure.
const BasicBlock * getParent() const
Definition: Instruction.h:72