1 //===- llvm/Analysis/ScalarEvolution.h - Scalar Evolution -------*- 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 // The ScalarEvolution class is an LLVM pass which can be used to analyze and
11 // catagorize scalar expressions in loops. It specializes in recognizing
12 // general induction variables, representing them with the abstract and opaque
13 // SCEV class. Given this analysis, trip counts of loops and other important
14 // properties can be obtained.
16 // This analysis is primarily useful for induction variable substitution and
17 // strength reduction.
19 //===----------------------------------------------------------------------===//
21 #ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H
22 #define LLVM_ANALYSIS_SCALAREVOLUTION_H
24 #include "llvm/Pass.h"
25 #include "llvm/Instructions.h"
26 #include "llvm/Function.h"
27 #include "llvm/System/DataTypes.h"
28 #include "llvm/Support/ValueHandle.h"
29 #include "llvm/Support/Allocator.h"
30 #include "llvm/Support/ConstantRange.h"
31 #include "llvm/ADT/FoldingSet.h"
32 #include "llvm/ADT/DenseMap.h"
41 class ScalarEvolution;
48 /// SCEV - This class represents an analyzed expression in the program. These
49 /// are opaque objects that the client is not allowed to do much with
52 class SCEV : public FastFoldingSetNode {
53 // The SCEV baseclass this node corresponds to
54 const unsigned short SCEVType;
57 /// SubclassData - This field is initialized to zero and may be used in
58 /// subclasses to store miscelaneous information.
59 unsigned short SubclassData;
62 SCEV(const SCEV &); // DO NOT IMPLEMENT
63 void operator=(const SCEV &); // DO NOT IMPLEMENT
67 explicit SCEV(const FoldingSetNodeID &ID, unsigned SCEVTy) :
68 FastFoldingSetNode(ID), SCEVType(SCEVTy), SubclassData(0) {}
70 unsigned getSCEVType() const { return SCEVType; }
72 /// isLoopInvariant - Return true if the value of this SCEV is unchanging in
73 /// the specified loop.
74 virtual bool isLoopInvariant(const Loop *L) const = 0;
76 /// hasComputableLoopEvolution - Return true if this SCEV changes value in a
77 /// known way in the specified loop. This property being true implies that
78 /// the value is variant in the loop AND that we can emit an expression to
79 /// compute the value of the expression at any particular loop iteration.
80 virtual bool hasComputableLoopEvolution(const Loop *L) const = 0;
82 /// getType - Return the LLVM type of this SCEV expression.
84 virtual const Type *getType() const = 0;
86 /// isZero - Return true if the expression is a constant zero.
90 /// isOne - Return true if the expression is a constant one.
94 /// isAllOnesValue - Return true if the expression is a constant
97 bool isAllOnesValue() const;
99 /// hasOperand - Test whether this SCEV has Op as a direct or
100 /// indirect operand.
101 virtual bool hasOperand(const SCEV *Op) const = 0;
103 /// dominates - Return true if elements that makes up this SCEV dominates
104 /// the specified basic block.
105 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0;
107 /// properlyDominates - Return true if elements that makes up this SCEV
108 /// properly dominate the specified basic block.
109 virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const = 0;
111 /// print - Print out the internal representation of this scalar to the
112 /// specified stream. This should really only be used for debugging
114 virtual void print(raw_ostream &OS) const = 0;
116 /// dump - This method is used for debugging.
121 inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
126 /// SCEVCouldNotCompute - An object of this class is returned by queries that
127 /// could not be answered. For example, if you ask for the number of
128 /// iterations of a linked-list traversal loop, you will get one of these.
129 /// None of the standard SCEV operations are valid on this class, it is just a
131 struct SCEVCouldNotCompute : public SCEV {
132 SCEVCouldNotCompute();
134 // None of these methods are valid for this object.
135 virtual bool isLoopInvariant(const Loop *L) const;
136 virtual const Type *getType() const;
137 virtual bool hasComputableLoopEvolution(const Loop *L) const;
138 virtual void print(raw_ostream &OS) const;
139 virtual bool hasOperand(const SCEV *Op) const;
141 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
145 virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
149 /// Methods for support type inquiry through isa, cast, and dyn_cast:
150 static inline bool classof(const SCEVCouldNotCompute *S) { return true; }
151 static bool classof(const SCEV *S);
154 /// ScalarEvolution - This class is the main scalar evolution driver. Because
155 /// client code (intentionally) can't do much with the SCEV objects directly,
156 /// they must ask this class for services.
158 class ScalarEvolution : public FunctionPass {
159 /// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
160 /// notified whenever a Value is deleted.
161 class SCEVCallbackVH : public CallbackVH {
163 virtual void deleted();
164 virtual void allUsesReplacedWith(Value *New);
166 SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
169 friend class SCEVCallbackVH;
170 friend struct SCEVExpander;
172 /// F - The function we are analyzing.
176 /// LI - The loop information for the function we are currently analyzing.
180 /// TD - The target data information for the target we are targetting.
184 /// CouldNotCompute - This SCEV is used to represent unknown trip
185 /// counts and things.
186 SCEVCouldNotCompute CouldNotCompute;
188 /// Scalars - This is a cache of the scalars we have analyzed so far.
190 std::map<SCEVCallbackVH, const SCEV *> Scalars;
192 /// BackedgeTakenInfo - Information about the backedge-taken count
193 /// of a loop. This currently inclues an exact count and a maximum count.
195 struct BackedgeTakenInfo {
196 /// Exact - An expression indicating the exact backedge-taken count of
197 /// the loop if it is known, or a SCEVCouldNotCompute otherwise.
200 /// Max - An expression indicating the least maximum backedge-taken
201 /// count of the loop that is known, or a SCEVCouldNotCompute.
204 /*implicit*/ BackedgeTakenInfo(const SCEV *exact) :
205 Exact(exact), Max(exact) {}
207 BackedgeTakenInfo(const SCEV *exact, const SCEV *max) :
208 Exact(exact), Max(max) {}
210 /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
211 /// computed information, or whether it's all SCEVCouldNotCompute
213 bool hasAnyInfo() const {
214 return !isa<SCEVCouldNotCompute>(Exact) ||
215 !isa<SCEVCouldNotCompute>(Max);
219 /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
220 /// this function as they are computed.
221 std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
223 /// ConstantEvolutionLoopExitValue - This map contains entries for all of
224 /// the PHI instructions that we attempt to compute constant evolutions for.
225 /// This allows us to avoid potentially expensive recomputation of these
226 /// properties. An instruction maps to null if we are unable to compute its
228 std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
230 /// ValuesAtScopes - This map contains entries for all the expressions
231 /// that we attempt to compute getSCEVAtScope information for, which can
232 /// be expensive in extreme cases.
233 std::map<const SCEV *,
234 std::map<const Loop *, const SCEV *> > ValuesAtScopes;
236 /// createSCEV - We know that there is no SCEV for the specified value.
237 /// Analyze the expression.
238 const SCEV *createSCEV(Value *V);
240 /// createNodeForPHI - Provide the special handling we need to analyze PHI
242 const SCEV *createNodeForPHI(PHINode *PN);
244 /// createNodeForGEP - Provide the special handling we need to analyze GEP
246 const SCEV *createNodeForGEP(Operator *GEP);
248 /// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
249 /// at most once for each SCEV+Loop pair.
251 const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
253 /// ForgetSymbolicValue - This looks up computed SCEV values for all
254 /// instructions that depend on the given instruction and removes them from
255 /// the Scalars map if they reference SymName. This is used during PHI
257 void ForgetSymbolicName(Instruction *I, const SCEV *SymName);
259 /// getBECount - Subtract the end and start values and divide by the step,
260 /// rounding up, to get the number of times the backedge is executed. Return
261 /// CouldNotCompute if an intermediate computation overflows.
262 const SCEV *getBECount(const SCEV *Start,
267 /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given
268 /// loop, lazily computing new values if the loop hasn't been analyzed
270 const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L);
272 /// ComputeBackedgeTakenCount - Compute the number of times the specified
273 /// loop will iterate.
274 BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
276 /// ComputeBackedgeTakenCountFromExit - Compute the number of times the
277 /// backedge of the specified loop will execute if it exits via the
279 BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L,
280 BasicBlock *ExitingBlock);
282 /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
283 /// backedge of the specified loop will execute if its exit condition
284 /// were a conditional branch of ExitCond, TBB, and FBB.
286 ComputeBackedgeTakenCountFromExitCond(const Loop *L,
291 /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of
292 /// times the backedge of the specified loop will execute if its exit
293 /// condition were a conditional branch of the ICmpInst ExitCond, TBB,
296 ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
301 /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition
302 /// of 'icmp op load X, cst', try to see if we can compute the
303 /// backedge-taken count.
305 ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI,
308 ICmpInst::Predicate p);
310 /// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute
311 /// a constant number of times (the condition evolves only from constants),
312 /// try to evaluate a few iterations of the loop until we get the exit
313 /// condition gets a value of ExitWhen (true or false). If we cannot
314 /// evaluate the backedge-taken count of the loop, return CouldNotCompute.
315 const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L,
319 /// HowFarToZero - Return the number of times a backedge comparing the
320 /// specified value to zero will execute. If not computable, return
322 const SCEV *HowFarToZero(const SCEV *V, const Loop *L);
324 /// HowFarToNonZero - Return the number of times a backedge checking the
325 /// specified value for nonzero will execute. If not computable, return
327 const SCEV *HowFarToNonZero(const SCEV *V, const Loop *L);
329 /// HowManyLessThans - Return the number of times a backedge containing the
330 /// specified less-than comparison will execute. If not computable, return
331 /// CouldNotCompute. isSigned specifies whether the less-than is signed.
332 BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
333 const Loop *L, bool isSigned);
335 /// getLoopPredecessor - If the given loop's header has exactly one unique
336 /// predecessor outside the loop, return it. Otherwise return null.
337 BasicBlock *getLoopPredecessor(const Loop *L);
339 /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
340 /// (which may not be an immediate predecessor) which has exactly one
341 /// successor from which BB is reachable, or null if no such block is
343 BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
345 /// isImpliedCond - Test whether the condition described by Pred, LHS,
346 /// and RHS is true whenever the given Cond value evaluates to true.
347 bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred,
348 const SCEV *LHS, const SCEV *RHS,
351 /// isImpliedCondOperands - Test whether the condition described by Pred,
352 /// LHS, and RHS is true whenever the condition desribed by Pred, FoundLHS,
353 /// and FoundRHS is true.
354 bool isImpliedCondOperands(ICmpInst::Predicate Pred,
355 const SCEV *LHS, const SCEV *RHS,
356 const SCEV *FoundLHS, const SCEV *FoundRHS);
358 /// isImpliedCondOperandsHelper - Test whether the condition described by
359 /// Pred, LHS, and RHS is true whenever the condition desribed by Pred,
360 /// FoundLHS, and FoundRHS is true.
361 bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
362 const SCEV *LHS, const SCEV *RHS,
363 const SCEV *FoundLHS, const SCEV *FoundRHS);
365 /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
366 /// in the header of its containing loop, we know the loop executes a
367 /// constant number of times, and the PHI node is just a recurrence
368 /// involving constants, fold it.
369 Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
373 static char ID; // Pass identification, replacement for typeid
376 LLVMContext &getContext() const { return F->getContext(); }
378 /// isSCEVable - Test if values of the given type are analyzable within
379 /// the SCEV framework. This primarily includes integer types, and it
380 /// can optionally include pointer types if the ScalarEvolution class
381 /// has access to target-specific information.
382 bool isSCEVable(const Type *Ty) const;
384 /// getTypeSizeInBits - Return the size in bits of the specified type,
385 /// for which isSCEVable must return true.
386 uint64_t getTypeSizeInBits(const Type *Ty) const;
388 /// getEffectiveSCEVType - Return a type with the same bitwidth as
389 /// the given type and which represents how SCEV will treat the given
390 /// type, for which isSCEVable must return true. For pointer types,
391 /// this is the pointer-sized integer type.
392 const Type *getEffectiveSCEVType(const Type *Ty) const;
394 /// getSCEV - Return a SCEV expression for the full generality of the
395 /// specified expression.
396 const SCEV *getSCEV(Value *V);
398 const SCEV *getConstant(ConstantInt *V);
399 const SCEV *getConstant(const APInt& Val);
400 const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false);
401 const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty);
402 const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty);
403 const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty);
404 const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty);
405 const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
406 bool HasNUW = false, bool HasNSW = false);
407 const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
408 bool HasNUW = false, bool HasNSW = false) {
409 SmallVector<const SCEV *, 2> Ops;
412 return getAddExpr(Ops, HasNUW, HasNSW);
414 const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1,
416 bool HasNUW = false, bool HasNSW = false) {
417 SmallVector<const SCEV *, 3> Ops;
421 return getAddExpr(Ops, HasNUW, HasNSW);
423 const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
424 bool HasNUW = false, bool HasNSW = false);
425 const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
426 bool HasNUW = false, bool HasNSW = false) {
427 SmallVector<const SCEV *, 2> Ops;
430 return getMulExpr(Ops, HasNUW, HasNSW);
432 const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
433 const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
435 bool HasNUW = false, bool HasNSW = false);
436 const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
438 bool HasNUW = false, bool HasNSW = false);
439 const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
441 bool HasNUW = false, bool HasNSW = false) {
442 SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
443 return getAddRecExpr(NewOp, L, HasNUW, HasNSW);
445 const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
446 const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
447 const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
448 const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
449 const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
450 const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
451 const SCEV *getFieldOffsetExpr(const StructType *STy, unsigned FieldNo);
452 const SCEV *getAllocSizeExpr(const Type *AllocTy);
453 const SCEV *getUnknown(Value *V);
454 const SCEV *getCouldNotCompute();
456 /// getNegativeSCEV - Return the SCEV object corresponding to -V.
458 const SCEV *getNegativeSCEV(const SCEV *V);
460 /// getNotSCEV - Return the SCEV object corresponding to ~V.
462 const SCEV *getNotSCEV(const SCEV *V);
464 /// getMinusSCEV - Return LHS-RHS.
466 const SCEV *getMinusSCEV(const SCEV *LHS,
469 /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
470 /// of the input value to the specified type. If the type must be
471 /// extended, it is zero extended.
472 const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty);
474 /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
475 /// of the input value to the specified type. If the type must be
476 /// extended, it is sign extended.
477 const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty);
479 /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
480 /// the input value to the specified type. If the type must be extended,
481 /// it is zero extended. The conversion must not be narrowing.
482 const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty);
484 /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
485 /// the input value to the specified type. If the type must be extended,
486 /// it is sign extended. The conversion must not be narrowing.
487 const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty);
489 /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
490 /// the input value to the specified type. If the type must be extended,
491 /// it is extended with unspecified bits. The conversion must not be
493 const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty);
495 /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
496 /// input value to the specified type. The conversion must not be
498 const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty);
500 /// getIntegerSCEV - Given a SCEVable type, create a constant for the
501 /// specified signed integer value and return a SCEV for the constant.
502 const SCEV *getIntegerSCEV(int Val, const Type *Ty);
504 /// getUMaxFromMismatchedTypes - Promote the operands to the wider of
505 /// the types using zero-extension, and then perform a umax operation
507 const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
510 /// getUMinFromMismatchedTypes - Promote the operands to the wider of
511 /// the types using zero-extension, and then perform a umin operation
513 const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
516 /// getSCEVAtScope - Return a SCEV expression for the specified value
517 /// at the specified scope in the program. The L value specifies a loop
518 /// nest to evaluate the expression at, where null is the top-level or a
519 /// specified loop is immediately inside of the loop.
521 /// This method can be used to compute the exit value for a variable defined
522 /// in a loop by querying what the value will hold in the parent loop.
524 /// In the case that a relevant loop exit value cannot be computed, the
525 /// original value V is returned.
526 const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
528 /// getSCEVAtScope - This is a convenience function which does
529 /// getSCEVAtScope(getSCEV(V), L).
530 const SCEV *getSCEVAtScope(Value *V, const Loop *L);
532 /// isLoopGuardedByCond - Test whether entry to the loop is protected by
533 /// a conditional between LHS and RHS. This is used to help avoid max
534 /// expressions in loop trip counts, and to eliminate casts.
535 bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
536 const SCEV *LHS, const SCEV *RHS);
538 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
539 /// protected by a conditional between LHS and RHS. This is used to
540 /// to eliminate casts.
541 bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
542 const SCEV *LHS, const SCEV *RHS);
544 /// getBackedgeTakenCount - If the specified loop has a predictable
545 /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
546 /// object. The backedge-taken count is the number of times the loop header
547 /// will be branched to from within the loop. This is one less than the
548 /// trip count of the loop, since it doesn't count the first iteration,
549 /// when the header is branched to from outside the loop.
551 /// Note that it is not valid to call this method on a loop without a
552 /// loop-invariant backedge-taken count (see
553 /// hasLoopInvariantBackedgeTakenCount).
555 const SCEV *getBackedgeTakenCount(const Loop *L);
557 /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
558 /// return the least SCEV value that is known never to be less than the
559 /// actual backedge taken count.
560 const SCEV *getMaxBackedgeTakenCount(const Loop *L);
562 /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
563 /// has an analyzable loop-invariant backedge-taken count.
564 bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
566 /// forgetLoop - This method should be called by the client when it has
567 /// changed a loop in a way that may effect ScalarEvolution's ability to
568 /// compute a trip count, or if the loop is deleted.
569 void forgetLoop(const Loop *L);
571 /// GetMinTrailingZeros - Determine the minimum number of zero bits that S
572 /// is guaranteed to end in (at every loop iteration). It is, at the same
573 /// time, the minimum number of times S is divisible by 2. For example,
574 /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
576 uint32_t GetMinTrailingZeros(const SCEV *S);
578 /// getUnsignedRange - Determine the unsigned range for a particular SCEV.
580 ConstantRange getUnsignedRange(const SCEV *S);
582 /// getSignedRange - Determine the signed range for a particular SCEV.
584 ConstantRange getSignedRange(const SCEV *S);
586 /// isKnownNegative - Test if the given expression is known to be negative.
588 bool isKnownNegative(const SCEV *S);
590 /// isKnownPositive - Test if the given expression is known to be positive.
592 bool isKnownPositive(const SCEV *S);
594 /// isKnownNonNegative - Test if the given expression is known to be
597 bool isKnownNonNegative(const SCEV *S);
599 /// isKnownNonPositive - Test if the given expression is known to be
602 bool isKnownNonPositive(const SCEV *S);
604 /// isKnownNonZero - Test if the given expression is known to be
607 bool isKnownNonZero(const SCEV *S);
609 /// isKnownNonZero - Test if the given expression is known to satisfy
610 /// the condition described by Pred, LHS, and RHS.
612 bool isKnownPredicate(ICmpInst::Predicate Pred,
613 const SCEV *LHS, const SCEV *RHS);
615 virtual bool runOnFunction(Function &F);
616 virtual void releaseMemory();
617 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
618 virtual void print(raw_ostream &OS, const Module* = 0) const;
621 FoldingSet<SCEV> UniqueSCEVs;
622 BumpPtrAllocator SCEVAllocator;