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 // categorize 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;
49 /// SCEV - This class represents an analyzed expression in the program. These
50 /// are opaque objects that the client is not allowed to do much with
53 class SCEV : public FoldingSetNode {
54 /// FastID - A reference to an Interned FoldingSetNodeID for this node.
55 /// The ScalarEvolution's BumpPtrAllocator holds the data.
56 FoldingSetNodeIDRef FastID;
58 // The SCEV baseclass this node corresponds to
59 const unsigned short SCEVType;
62 /// SubclassData - This field is initialized to zero and may be used in
63 /// subclasses to store miscellaneous information.
64 unsigned short SubclassData;
67 SCEV(const SCEV &); // DO NOT IMPLEMENT
68 void operator=(const SCEV &); // DO NOT IMPLEMENT
72 explicit SCEV(const FoldingSetNodeIDRef ID, unsigned SCEVTy) :
73 FastID(ID), SCEVType(SCEVTy), SubclassData(0) {}
75 unsigned getSCEVType() const { return SCEVType; }
77 /// Profile - FoldingSet support.
78 void Profile(FoldingSetNodeID& ID) { ID = FastID; }
80 /// isLoopInvariant - Return true if the value of this SCEV is unchanging in
81 /// the specified loop.
82 virtual bool isLoopInvariant(const Loop *L) const = 0;
84 /// hasComputableLoopEvolution - Return true if this SCEV changes value in a
85 /// known way in the specified loop. This property being true implies that
86 /// the value is variant in the loop AND that we can emit an expression to
87 /// compute the value of the expression at any particular loop iteration.
88 virtual bool hasComputableLoopEvolution(const Loop *L) const = 0;
90 /// getType - Return the LLVM type of this SCEV expression.
92 virtual const Type *getType() const = 0;
94 /// isZero - Return true if the expression is a constant zero.
98 /// isOne - Return true if the expression is a constant one.
102 /// isAllOnesValue - Return true if the expression is a constant
105 bool isAllOnesValue() const;
107 /// hasOperand - Test whether this SCEV has Op as a direct or
108 /// indirect operand.
109 virtual bool hasOperand(const SCEV *Op) const = 0;
111 /// dominates - Return true if elements that makes up this SCEV dominates
112 /// the specified basic block.
113 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0;
115 /// properlyDominates - Return true if elements that makes up this SCEV
116 /// properly dominate the specified basic block.
117 virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const = 0;
119 /// print - Print out the internal representation of this scalar to the
120 /// specified stream. This should really only be used for debugging
122 virtual void print(raw_ostream &OS) const = 0;
124 /// dump - This method is used for debugging.
129 inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) {
134 /// SCEVCouldNotCompute - An object of this class is returned by queries that
135 /// could not be answered. For example, if you ask for the number of
136 /// iterations of a linked-list traversal loop, you will get one of these.
137 /// None of the standard SCEV operations are valid on this class, it is just a
139 struct SCEVCouldNotCompute : public SCEV {
140 SCEVCouldNotCompute();
142 // None of these methods are valid for this object.
143 virtual bool isLoopInvariant(const Loop *L) const;
144 virtual const Type *getType() const;
145 virtual bool hasComputableLoopEvolution(const Loop *L) const;
146 virtual void print(raw_ostream &OS) const;
147 virtual bool hasOperand(const SCEV *Op) const;
149 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const {
153 virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
157 /// Methods for support type inquiry through isa, cast, and dyn_cast:
158 static inline bool classof(const SCEVCouldNotCompute *S) { return true; }
159 static bool classof(const SCEV *S);
162 /// ScalarEvolution - This class is the main scalar evolution driver. Because
163 /// client code (intentionally) can't do much with the SCEV objects directly,
164 /// they must ask this class for services.
166 class ScalarEvolution : public FunctionPass {
167 /// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be
168 /// notified whenever a Value is deleted.
169 class SCEVCallbackVH : public CallbackVH {
171 virtual void deleted();
172 virtual void allUsesReplacedWith(Value *New);
174 SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0);
177 friend class SCEVCallbackVH;
178 friend class SCEVExpander;
179 friend class SCEVUnknown;
181 /// F - The function we are analyzing.
185 /// LI - The loop information for the function we are currently analyzing.
189 /// TD - The target data information for the target we are targeting.
193 /// DT - The dominator tree.
197 /// CouldNotCompute - This SCEV is used to represent unknown trip
198 /// counts and things.
199 SCEVCouldNotCompute CouldNotCompute;
201 /// Scalars - This is a cache of the scalars we have analyzed so far.
203 std::map<SCEVCallbackVH, const SCEV *> Scalars;
205 /// BackedgeTakenInfo - Information about the backedge-taken count
206 /// of a loop. This currently includes an exact count and a maximum count.
208 struct BackedgeTakenInfo {
209 /// Exact - An expression indicating the exact backedge-taken count of
210 /// the loop if it is known, or a SCEVCouldNotCompute otherwise.
213 /// Max - An expression indicating the least maximum backedge-taken
214 /// count of the loop that is known, or a SCEVCouldNotCompute.
217 /*implicit*/ BackedgeTakenInfo(const SCEV *exact) :
218 Exact(exact), Max(exact) {}
220 BackedgeTakenInfo(const SCEV *exact, const SCEV *max) :
221 Exact(exact), Max(max) {}
223 /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any
224 /// computed information, or whether it's all SCEVCouldNotCompute
226 bool hasAnyInfo() const {
227 return !isa<SCEVCouldNotCompute>(Exact) ||
228 !isa<SCEVCouldNotCompute>(Max);
232 /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for
233 /// this function as they are computed.
234 std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts;
236 /// ConstantEvolutionLoopExitValue - This map contains entries for all of
237 /// the PHI instructions that we attempt to compute constant evolutions for.
238 /// This allows us to avoid potentially expensive recomputation of these
239 /// properties. An instruction maps to null if we are unable to compute its
241 std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue;
243 /// ValuesAtScopes - This map contains entries for all the expressions
244 /// that we attempt to compute getSCEVAtScope information for, which can
245 /// be expensive in extreme cases.
246 std::map<const SCEV *,
247 std::map<const Loop *, const SCEV *> > ValuesAtScopes;
249 /// createSCEV - We know that there is no SCEV for the specified value.
250 /// Analyze the expression.
251 const SCEV *createSCEV(Value *V);
253 /// createNodeForPHI - Provide the special handling we need to analyze PHI
255 const SCEV *createNodeForPHI(PHINode *PN);
257 /// createNodeForGEP - Provide the special handling we need to analyze GEP
259 const SCEV *createNodeForGEP(GEPOperator *GEP);
261 /// computeSCEVAtScope - Implementation code for getSCEVAtScope; called
262 /// at most once for each SCEV+Loop pair.
264 const SCEV *computeSCEVAtScope(const SCEV *S, const Loop *L);
266 /// ForgetSymbolicValue - This looks up computed SCEV values for all
267 /// instructions that depend on the given instruction and removes them from
268 /// the Scalars map if they reference SymName. This is used during PHI
270 void ForgetSymbolicName(Instruction *I, const SCEV *SymName);
272 /// getBECount - Subtract the end and start values and divide by the step,
273 /// rounding up, to get the number of times the backedge is executed. Return
274 /// CouldNotCompute if an intermediate computation overflows.
275 const SCEV *getBECount(const SCEV *Start,
280 /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given
281 /// loop, lazily computing new values if the loop hasn't been analyzed
283 const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L);
285 /// ComputeBackedgeTakenCount - Compute the number of times the specified
286 /// loop will iterate.
287 BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L);
289 /// ComputeBackedgeTakenCountFromExit - Compute the number of times the
290 /// backedge of the specified loop will execute if it exits via the
292 BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L,
293 BasicBlock *ExitingBlock);
295 /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
296 /// backedge of the specified loop will execute if its exit condition
297 /// were a conditional branch of ExitCond, TBB, and FBB.
299 ComputeBackedgeTakenCountFromExitCond(const Loop *L,
304 /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of
305 /// times the backedge of the specified loop will execute if its exit
306 /// condition were a conditional branch of the ICmpInst ExitCond, TBB,
309 ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
314 /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition
315 /// of 'icmp op load X, cst', try to see if we can compute the
316 /// backedge-taken count.
318 ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI,
321 ICmpInst::Predicate p);
323 /// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute
324 /// a constant number of times (the condition evolves only from constants),
325 /// try to evaluate a few iterations of the loop until we get the exit
326 /// condition gets a value of ExitWhen (true or false). If we cannot
327 /// evaluate the backedge-taken count of the loop, return CouldNotCompute.
328 const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L,
332 /// HowFarToZero - Return the number of times a backedge comparing the
333 /// specified value to zero will execute. If not computable, return
335 BackedgeTakenInfo HowFarToZero(const SCEV *V, const Loop *L);
337 /// HowFarToNonZero - Return the number of times a backedge checking the
338 /// specified value for nonzero will execute. If not computable, return
340 BackedgeTakenInfo HowFarToNonZero(const SCEV *V, const Loop *L);
342 /// HowManyLessThans - Return the number of times a backedge containing the
343 /// specified less-than comparison will execute. If not computable, return
344 /// CouldNotCompute. isSigned specifies whether the less-than is signed.
345 BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
346 const Loop *L, bool isSigned);
348 /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
349 /// (which may not be an immediate predecessor) which has exactly one
350 /// successor from which BB is reachable, or null if no such block is
352 std::pair<BasicBlock *, BasicBlock *>
353 getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB);
355 /// isImpliedCond - Test whether the condition described by Pred, LHS,
356 /// and RHS is true whenever the given Cond value evaluates to true.
357 bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred,
358 const SCEV *LHS, const SCEV *RHS,
361 /// isImpliedCondOperands - Test whether the condition described by Pred,
362 /// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
363 /// and FoundRHS is true.
364 bool isImpliedCondOperands(ICmpInst::Predicate Pred,
365 const SCEV *LHS, const SCEV *RHS,
366 const SCEV *FoundLHS, const SCEV *FoundRHS);
368 /// isImpliedCondOperandsHelper - Test whether the condition described by
369 /// Pred, LHS, and RHS is true whenever the condition described by Pred,
370 /// FoundLHS, and FoundRHS is true.
371 bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
372 const SCEV *LHS, const SCEV *RHS,
373 const SCEV *FoundLHS, const SCEV *FoundRHS);
375 /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
376 /// in the header of its containing loop, we know the loop executes a
377 /// constant number of times, and the PHI node is just a recurrence
378 /// involving constants, fold it.
379 Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
382 /// isKnownPredicateWithRanges - Test if the given expression is known to
383 /// satisfy the condition described by Pred and the known constant ranges
386 bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
387 const SCEV *LHS, const SCEV *RHS);
390 static char ID; // Pass identification, replacement for typeid
393 LLVMContext &getContext() const { return F->getContext(); }
395 /// isSCEVable - Test if values of the given type are analyzable within
396 /// the SCEV framework. This primarily includes integer types, and it
397 /// can optionally include pointer types if the ScalarEvolution class
398 /// has access to target-specific information.
399 bool isSCEVable(const Type *Ty) const;
401 /// getTypeSizeInBits - Return the size in bits of the specified type,
402 /// for which isSCEVable must return true.
403 uint64_t getTypeSizeInBits(const Type *Ty) const;
405 /// getEffectiveSCEVType - Return a type with the same bitwidth as
406 /// the given type and which represents how SCEV will treat the given
407 /// type, for which isSCEVable must return true. For pointer types,
408 /// this is the pointer-sized integer type.
409 const Type *getEffectiveSCEVType(const Type *Ty) const;
411 /// getSCEV - Return a SCEV expression for the full generality of the
412 /// specified expression.
413 const SCEV *getSCEV(Value *V);
415 const SCEV *getConstant(ConstantInt *V);
416 const SCEV *getConstant(const APInt& Val);
417 const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false);
418 const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty);
419 const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty);
420 const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty);
421 const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty);
422 const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
423 bool HasNUW = false, bool HasNSW = false);
424 const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
425 bool HasNUW = false, bool HasNSW = false) {
426 SmallVector<const SCEV *, 2> Ops;
429 return getAddExpr(Ops, HasNUW, HasNSW);
431 const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1,
433 bool HasNUW = false, bool HasNSW = false) {
434 SmallVector<const SCEV *, 3> Ops;
438 return getAddExpr(Ops, HasNUW, HasNSW);
440 const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
441 bool HasNUW = false, bool HasNSW = false);
442 const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
443 bool HasNUW = false, bool HasNSW = false) {
444 SmallVector<const SCEV *, 2> Ops;
447 return getMulExpr(Ops, HasNUW, HasNSW);
449 const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
450 const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
452 bool HasNUW = false, bool HasNSW = false);
453 const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
455 bool HasNUW = false, bool HasNSW = false);
456 const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
458 bool HasNUW = false, bool HasNSW = false) {
459 SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
460 return getAddRecExpr(NewOp, L, HasNUW, HasNSW);
462 const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
463 const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
464 const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
465 const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
466 const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
467 const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
468 const SCEV *getUnknown(Value *V);
469 const SCEV *getCouldNotCompute();
471 /// getSizeOfExpr - Return an expression for sizeof on the given type.
473 const SCEV *getSizeOfExpr(const Type *AllocTy);
475 /// getAlignOfExpr - Return an expression for alignof on the given type.
477 const SCEV *getAlignOfExpr(const Type *AllocTy);
479 /// getOffsetOfExpr - Return an expression for offsetof on the given field.
481 const SCEV *getOffsetOfExpr(const StructType *STy, unsigned FieldNo);
483 /// getOffsetOfExpr - Return an expression for offsetof on the given field.
485 const SCEV *getOffsetOfExpr(const Type *CTy, Constant *FieldNo);
487 /// getNegativeSCEV - Return the SCEV object corresponding to -V.
489 const SCEV *getNegativeSCEV(const SCEV *V);
491 /// getNotSCEV - Return the SCEV object corresponding to ~V.
493 const SCEV *getNotSCEV(const SCEV *V);
495 /// getMinusSCEV - Return LHS-RHS.
497 const SCEV *getMinusSCEV(const SCEV *LHS,
500 /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
501 /// of the input value to the specified type. If the type must be
502 /// extended, it is zero extended.
503 const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty);
505 /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
506 /// of the input value to the specified type. If the type must be
507 /// extended, it is sign extended.
508 const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty);
510 /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
511 /// the input value to the specified type. If the type must be extended,
512 /// it is zero extended. The conversion must not be narrowing.
513 const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty);
515 /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
516 /// the input value to the specified type. If the type must be extended,
517 /// it is sign extended. The conversion must not be narrowing.
518 const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty);
520 /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
521 /// the input value to the specified type. If the type must be extended,
522 /// it is extended with unspecified bits. The conversion must not be
524 const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty);
526 /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
527 /// input value to the specified type. The conversion must not be
529 const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty);
531 /// getUMaxFromMismatchedTypes - Promote the operands to the wider of
532 /// the types using zero-extension, and then perform a umax operation
534 const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
537 /// getUMinFromMismatchedTypes - Promote the operands to the wider of
538 /// the types using zero-extension, and then perform a umin operation
540 const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
543 /// getSCEVAtScope - Return a SCEV expression for the specified value
544 /// at the specified scope in the program. The L value specifies a loop
545 /// nest to evaluate the expression at, where null is the top-level or a
546 /// specified loop is immediately inside of the loop.
548 /// This method can be used to compute the exit value for a variable defined
549 /// in a loop by querying what the value will hold in the parent loop.
551 /// In the case that a relevant loop exit value cannot be computed, the
552 /// original value V is returned.
553 const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
555 /// getSCEVAtScope - This is a convenience function which does
556 /// getSCEVAtScope(getSCEV(V), L).
557 const SCEV *getSCEVAtScope(Value *V, const Loop *L);
559 /// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
560 /// by a conditional between LHS and RHS. This is used to help avoid max
561 /// expressions in loop trip counts, and to eliminate casts.
562 bool isLoopEntryGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
563 const SCEV *LHS, const SCEV *RHS);
565 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
566 /// protected by a conditional between LHS and RHS. This is used to
567 /// to eliminate casts.
568 bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
569 const SCEV *LHS, const SCEV *RHS);
571 /// getBackedgeTakenCount - If the specified loop has a predictable
572 /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
573 /// object. The backedge-taken count is the number of times the loop header
574 /// will be branched to from within the loop. This is one less than the
575 /// trip count of the loop, since it doesn't count the first iteration,
576 /// when the header is branched to from outside the loop.
578 /// Note that it is not valid to call this method on a loop without a
579 /// loop-invariant backedge-taken count (see
580 /// hasLoopInvariantBackedgeTakenCount).
582 const SCEV *getBackedgeTakenCount(const Loop *L);
584 /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
585 /// return the least SCEV value that is known never to be less than the
586 /// actual backedge taken count.
587 const SCEV *getMaxBackedgeTakenCount(const Loop *L);
589 /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
590 /// has an analyzable loop-invariant backedge-taken count.
591 bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
593 /// forgetLoop - This method should be called by the client when it has
594 /// changed a loop in a way that may effect ScalarEvolution's ability to
595 /// compute a trip count, or if the loop is deleted.
596 void forgetLoop(const Loop *L);
598 /// forgetValue - This method should be called by the client when it has
599 /// changed a value in a way that may effect its value, or which may
600 /// disconnect it from a def-use chain linking it to a loop.
601 void forgetValue(Value *V);
603 /// GetMinTrailingZeros - Determine the minimum number of zero bits that S
604 /// is guaranteed to end in (at every loop iteration). It is, at the same
605 /// time, the minimum number of times S is divisible by 2. For example,
606 /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
608 uint32_t GetMinTrailingZeros(const SCEV *S);
610 /// getUnsignedRange - Determine the unsigned range for a particular SCEV.
612 ConstantRange getUnsignedRange(const SCEV *S);
614 /// getSignedRange - Determine the signed range for a particular SCEV.
616 ConstantRange getSignedRange(const SCEV *S);
618 /// isKnownNegative - Test if the given expression is known to be negative.
620 bool isKnownNegative(const SCEV *S);
622 /// isKnownPositive - Test if the given expression is known to be positive.
624 bool isKnownPositive(const SCEV *S);
626 /// isKnownNonNegative - Test if the given expression is known to be
629 bool isKnownNonNegative(const SCEV *S);
631 /// isKnownNonPositive - Test if the given expression is known to be
634 bool isKnownNonPositive(const SCEV *S);
636 /// isKnownNonZero - Test if the given expression is known to be
639 bool isKnownNonZero(const SCEV *S);
641 /// isKnownPredicate - Test if the given expression is known to satisfy
642 /// the condition described by Pred, LHS, and RHS.
644 bool isKnownPredicate(ICmpInst::Predicate Pred,
645 const SCEV *LHS, const SCEV *RHS);
647 /// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
648 /// predicate Pred. Return true iff any changes were made. If the
649 /// operands are provably equal or inequal, LHS and RHS are set to
650 /// the same value and Pred is set to either ICMP_EQ or ICMP_NE.
652 bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
656 virtual bool runOnFunction(Function &F);
657 virtual void releaseMemory();
658 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
659 virtual void print(raw_ostream &OS, const Module* = 0) const;
662 FoldingSet<SCEV> UniqueSCEVs;
663 BumpPtrAllocator SCEVAllocator;
665 /// FirstUnknown - The head of a linked list of all SCEVUnknown
666 /// values that have been allocated. This is used by releaseMemory
667 /// to locate them all and call their destructors.
668 SCEVUnknown *FirstUnknown;