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, and
356 /// RHS is true whenever the given FoundCondValue value evaluates to true.
357 bool isImpliedCond(ICmpInst::Predicate Pred,
358 const SCEV *LHS, const SCEV *RHS,
359 Value *FoundCondValue,
362 /// isImpliedCondOperands - Test whether the condition described by Pred,
363 /// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
364 /// and FoundRHS is true.
365 bool isImpliedCondOperands(ICmpInst::Predicate Pred,
366 const SCEV *LHS, const SCEV *RHS,
367 const SCEV *FoundLHS, const SCEV *FoundRHS);
369 /// isImpliedCondOperandsHelper - Test whether the condition described by
370 /// Pred, LHS, and RHS is true whenever the condition described by Pred,
371 /// FoundLHS, and FoundRHS is true.
372 bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
373 const SCEV *LHS, const SCEV *RHS,
374 const SCEV *FoundLHS, const SCEV *FoundRHS);
376 /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
377 /// in the header of its containing loop, we know the loop executes a
378 /// constant number of times, and the PHI node is just a recurrence
379 /// involving constants, fold it.
380 Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs,
383 /// isKnownPredicateWithRanges - Test if the given expression is known to
384 /// satisfy the condition described by Pred and the known constant ranges
387 bool isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
388 const SCEV *LHS, const SCEV *RHS);
391 static char ID; // Pass identification, replacement for typeid
394 LLVMContext &getContext() const { return F->getContext(); }
396 /// isSCEVable - Test if values of the given type are analyzable within
397 /// the SCEV framework. This primarily includes integer types, and it
398 /// can optionally include pointer types if the ScalarEvolution class
399 /// has access to target-specific information.
400 bool isSCEVable(const Type *Ty) const;
402 /// getTypeSizeInBits - Return the size in bits of the specified type,
403 /// for which isSCEVable must return true.
404 uint64_t getTypeSizeInBits(const Type *Ty) const;
406 /// getEffectiveSCEVType - Return a type with the same bitwidth as
407 /// the given type and which represents how SCEV will treat the given
408 /// type, for which isSCEVable must return true. For pointer types,
409 /// this is the pointer-sized integer type.
410 const Type *getEffectiveSCEVType(const Type *Ty) const;
412 /// getSCEV - Return a SCEV expression for the full generality of the
413 /// specified expression.
414 const SCEV *getSCEV(Value *V);
416 const SCEV *getConstant(ConstantInt *V);
417 const SCEV *getConstant(const APInt& Val);
418 const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false);
419 const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty);
420 const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty);
421 const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty);
422 const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty);
423 const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
424 bool HasNUW = false, bool HasNSW = false);
425 const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS,
426 bool HasNUW = false, bool HasNSW = false) {
427 SmallVector<const SCEV *, 2> Ops;
430 return getAddExpr(Ops, HasNUW, HasNSW);
432 const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1,
434 bool HasNUW = false, bool HasNSW = false) {
435 SmallVector<const SCEV *, 3> Ops;
439 return getAddExpr(Ops, HasNUW, HasNSW);
441 const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
442 bool HasNUW = false, bool HasNSW = false);
443 const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS,
444 bool HasNUW = false, bool HasNSW = false) {
445 SmallVector<const SCEV *, 2> Ops;
448 return getMulExpr(Ops, HasNUW, HasNSW);
450 const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS);
451 const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step,
453 bool HasNUW = false, bool HasNSW = false);
454 const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
456 bool HasNUW = false, bool HasNSW = false);
457 const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands,
459 bool HasNUW = false, bool HasNSW = false) {
460 SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end());
461 return getAddRecExpr(NewOp, L, HasNUW, HasNSW);
463 const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS);
464 const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
465 const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS);
466 const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
467 const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
468 const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
469 const SCEV *getUnknown(Value *V);
470 const SCEV *getCouldNotCompute();
472 /// getSizeOfExpr - Return an expression for sizeof on the given type.
474 const SCEV *getSizeOfExpr(const Type *AllocTy);
476 /// getAlignOfExpr - Return an expression for alignof on the given type.
478 const SCEV *getAlignOfExpr(const Type *AllocTy);
480 /// getOffsetOfExpr - Return an expression for offsetof on the given field.
482 const SCEV *getOffsetOfExpr(const StructType *STy, unsigned FieldNo);
484 /// getOffsetOfExpr - Return an expression for offsetof on the given field.
486 const SCEV *getOffsetOfExpr(const Type *CTy, Constant *FieldNo);
488 /// getNegativeSCEV - Return the SCEV object corresponding to -V.
490 const SCEV *getNegativeSCEV(const SCEV *V);
492 /// getNotSCEV - Return the SCEV object corresponding to ~V.
494 const SCEV *getNotSCEV(const SCEV *V);
496 /// getMinusSCEV - Return LHS-RHS.
498 const SCEV *getMinusSCEV(const SCEV *LHS,
501 /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion
502 /// of the input value to the specified type. If the type must be
503 /// extended, it is zero extended.
504 const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty);
506 /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion
507 /// of the input value to the specified type. If the type must be
508 /// extended, it is sign extended.
509 const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty);
511 /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of
512 /// the input value to the specified type. If the type must be extended,
513 /// it is zero extended. The conversion must not be narrowing.
514 const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty);
516 /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of
517 /// the input value to the specified type. If the type must be extended,
518 /// it is sign extended. The conversion must not be narrowing.
519 const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty);
521 /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
522 /// the input value to the specified type. If the type must be extended,
523 /// it is extended with unspecified bits. The conversion must not be
525 const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty);
527 /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
528 /// input value to the specified type. The conversion must not be
530 const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty);
532 /// getUMaxFromMismatchedTypes - Promote the operands to the wider of
533 /// the types using zero-extension, and then perform a umax operation
535 const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS,
538 /// getUMinFromMismatchedTypes - Promote the operands to the wider of
539 /// the types using zero-extension, and then perform a umin operation
541 const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS,
544 /// getSCEVAtScope - Return a SCEV expression for the specified value
545 /// at the specified scope in the program. The L value specifies a loop
546 /// nest to evaluate the expression at, where null is the top-level or a
547 /// specified loop is immediately inside of the loop.
549 /// This method can be used to compute the exit value for a variable defined
550 /// in a loop by querying what the value will hold in the parent loop.
552 /// In the case that a relevant loop exit value cannot be computed, the
553 /// original value V is returned.
554 const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L);
556 /// getSCEVAtScope - This is a convenience function which does
557 /// getSCEVAtScope(getSCEV(V), L).
558 const SCEV *getSCEVAtScope(Value *V, const Loop *L);
560 /// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
561 /// by a conditional between LHS and RHS. This is used to help avoid max
562 /// expressions in loop trip counts, and to eliminate casts.
563 bool isLoopEntryGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
564 const SCEV *LHS, const SCEV *RHS);
566 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
567 /// protected by a conditional between LHS and RHS. This is used to
568 /// to eliminate casts.
569 bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred,
570 const SCEV *LHS, const SCEV *RHS);
572 /// getBackedgeTakenCount - If the specified loop has a predictable
573 /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
574 /// object. The backedge-taken count is the number of times the loop header
575 /// will be branched to from within the loop. This is one less than the
576 /// trip count of the loop, since it doesn't count the first iteration,
577 /// when the header is branched to from outside the loop.
579 /// Note that it is not valid to call this method on a loop without a
580 /// loop-invariant backedge-taken count (see
581 /// hasLoopInvariantBackedgeTakenCount).
583 const SCEV *getBackedgeTakenCount(const Loop *L);
585 /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
586 /// return the least SCEV value that is known never to be less than the
587 /// actual backedge taken count.
588 const SCEV *getMaxBackedgeTakenCount(const Loop *L);
590 /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop
591 /// has an analyzable loop-invariant backedge-taken count.
592 bool hasLoopInvariantBackedgeTakenCount(const Loop *L);
594 /// forgetLoop - This method should be called by the client when it has
595 /// changed a loop in a way that may effect ScalarEvolution's ability to
596 /// compute a trip count, or if the loop is deleted.
597 void forgetLoop(const Loop *L);
599 /// forgetValue - This method should be called by the client when it has
600 /// changed a value in a way that may effect its value, or which may
601 /// disconnect it from a def-use chain linking it to a loop.
602 void forgetValue(Value *V);
604 /// GetMinTrailingZeros - Determine the minimum number of zero bits that S
605 /// is guaranteed to end in (at every loop iteration). It is, at the same
606 /// time, the minimum number of times S is divisible by 2. For example,
607 /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the
609 uint32_t GetMinTrailingZeros(const SCEV *S);
611 /// getUnsignedRange - Determine the unsigned range for a particular SCEV.
613 ConstantRange getUnsignedRange(const SCEV *S);
615 /// getSignedRange - Determine the signed range for a particular SCEV.
617 ConstantRange getSignedRange(const SCEV *S);
619 /// isKnownNegative - Test if the given expression is known to be negative.
621 bool isKnownNegative(const SCEV *S);
623 /// isKnownPositive - Test if the given expression is known to be positive.
625 bool isKnownPositive(const SCEV *S);
627 /// isKnownNonNegative - Test if the given expression is known to be
630 bool isKnownNonNegative(const SCEV *S);
632 /// isKnownNonPositive - Test if the given expression is known to be
635 bool isKnownNonPositive(const SCEV *S);
637 /// isKnownNonZero - Test if the given expression is known to be
640 bool isKnownNonZero(const SCEV *S);
642 /// isKnownPredicate - Test if the given expression is known to satisfy
643 /// the condition described by Pred, LHS, and RHS.
645 bool isKnownPredicate(ICmpInst::Predicate Pred,
646 const SCEV *LHS, const SCEV *RHS);
648 /// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
649 /// predicate Pred. Return true iff any changes were made. If the
650 /// operands are provably equal or inequal, LHS and RHS are set to
651 /// the same value and Pred is set to either ICMP_EQ or ICMP_NE.
653 bool SimplifyICmpOperands(ICmpInst::Predicate &Pred,
657 virtual bool runOnFunction(Function &F);
658 virtual void releaseMemory();
659 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
660 virtual void print(raw_ostream &OS, const Module* = 0) const;
663 FoldingSet<SCEV> UniqueSCEVs;
664 BumpPtrAllocator SCEVAllocator;
666 /// FirstUnknown - The head of a linked list of all SCEVUnknown
667 /// values that have been allocated. This is used by releaseMemory
668 /// to locate them all and call their destructors.
669 SCEVUnknown *FirstUnknown;