ScalarEvolution.h revision 7e77f7959162a601291fd5400a88908d021033d3
1//===- llvm/Analysis/ScalarEvolution.h - Scalar Evolution -------*- C++ -*-===// 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// 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. 15// 16// This analysis is primarily useful for induction variable substitution and 17// strength reduction. 18// 19//===----------------------------------------------------------------------===// 20 21#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_H 22#define LLVM_ANALYSIS_SCALAREVOLUTION_H 23 24#include "llvm/Pass.h" 25#include "llvm/Instructions.h" 26#include "llvm/Support/DataTypes.h" 27#include "llvm/Support/ValueHandle.h" 28#include "llvm/Support/Allocator.h" 29#include "llvm/Support/ConstantRange.h" 30#include "llvm/ADT/FoldingSet.h" 31#include "llvm/ADT/DenseMap.h" 32#include <iosfwd> 33#include <map> 34 35namespace llvm { 36 class APInt; 37 class Constant; 38 class ConstantInt; 39 class DominatorTree; 40 class Type; 41 class ScalarEvolution; 42 class TargetData; 43 class LLVMContext; 44 class Loop; 45 class LoopInfo; 46 class Operator; 47 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 50 /// directly. 51 /// 52 class SCEV : public FastFoldingSetNode { 53 // The SCEV baseclass this node corresponds to 54 const unsigned short SCEVType; 55 56 protected: 57 /// SubclassData - This field is initialized to zero and may be used in 58 /// subclasses to store miscelaneous information. 59 unsigned short SubclassData; 60 61 private: 62 SCEV(const SCEV &); // DO NOT IMPLEMENT 63 void operator=(const SCEV &); // DO NOT IMPLEMENT 64 protected: 65 virtual ~SCEV(); 66 public: 67 explicit SCEV(const FoldingSetNodeID &ID, unsigned SCEVTy) : 68 FastFoldingSetNode(ID), SCEVType(SCEVTy), SubclassData(0) {} 69 70 unsigned getSCEVType() const { return SCEVType; } 71 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; 75 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; 81 82 /// getType - Return the LLVM type of this SCEV expression. 83 /// 84 virtual const Type *getType() const = 0; 85 86 /// isZero - Return true if the expression is a constant zero. 87 /// 88 bool isZero() const; 89 90 /// isOne - Return true if the expression is a constant one. 91 /// 92 bool isOne() const; 93 94 /// isAllOnesValue - Return true if the expression is a constant 95 /// all-ones value. 96 /// 97 bool isAllOnesValue() const; 98 99 /// hasOperand - Test whether this SCEV has Op as a direct or 100 /// indirect operand. 101 virtual bool hasOperand(const SCEV *Op) const = 0; 102 103 /// 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; 106 107 /// print - Print out the internal representation of this scalar to the 108 /// specified stream. This should really only be used for debugging 109 /// purposes. 110 virtual void print(raw_ostream &OS) const = 0; 111 void print(std::ostream &OS) const; 112 void print(std::ostream *OS) const { if (OS) print(*OS); } 113 114 /// dump - This method is used for debugging. 115 /// 116 void dump() const; 117 }; 118 119 inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) { 120 S.print(OS); 121 return OS; 122 } 123 124 inline std::ostream &operator<<(std::ostream &OS, const SCEV &S) { 125 S.print(OS); 126 return OS; 127 } 128 129 /// SCEVCouldNotCompute - An object of this class is returned by queries that 130 /// could not be answered. For example, if you ask for the number of 131 /// iterations of a linked-list traversal loop, you will get one of these. 132 /// None of the standard SCEV operations are valid on this class, it is just a 133 /// marker. 134 struct SCEVCouldNotCompute : public SCEV { 135 SCEVCouldNotCompute(); 136 137 // None of these methods are valid for this object. 138 virtual bool isLoopInvariant(const Loop *L) const; 139 virtual const Type *getType() const; 140 virtual bool hasComputableLoopEvolution(const Loop *L) const; 141 virtual void print(raw_ostream &OS) const; 142 virtual bool hasOperand(const SCEV *Op) const; 143 144 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const { 145 return true; 146 } 147 148 /// Methods for support type inquiry through isa, cast, and dyn_cast: 149 static inline bool classof(const SCEVCouldNotCompute *S) { return true; } 150 static bool classof(const SCEV *S); 151 }; 152 153 /// ScalarEvolution - This class is the main scalar evolution driver. Because 154 /// client code (intentionally) can't do much with the SCEV objects directly, 155 /// they must ask this class for services. 156 /// 157 class ScalarEvolution : public FunctionPass { 158 /// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be 159 /// notified whenever a Value is deleted. 160 class SCEVCallbackVH : public CallbackVH { 161 ScalarEvolution *SE; 162 virtual void deleted(); 163 virtual void allUsesReplacedWith(Value *New); 164 public: 165 SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0); 166 }; 167 168 friend class SCEVCallbackVH; 169 friend struct SCEVExpander; 170 171 /// F - The function we are analyzing. 172 /// 173 Function *F; 174 175 /// LI - The loop information for the function we are currently analyzing. 176 /// 177 LoopInfo *LI; 178 179 /// TD - The target data information for the target we are targetting. 180 /// 181 TargetData *TD; 182 183 /// CouldNotCompute - This SCEV is used to represent unknown trip 184 /// counts and things. 185 SCEVCouldNotCompute CouldNotCompute; 186 187 /// Scalars - This is a cache of the scalars we have analyzed so far. 188 /// 189 std::map<SCEVCallbackVH, const SCEV *> Scalars; 190 191 /// BackedgeTakenInfo - Information about the backedge-taken count 192 /// of a loop. This currently inclues an exact count and a maximum count. 193 /// 194 struct BackedgeTakenInfo { 195 /// Exact - An expression indicating the exact backedge-taken count of 196 /// the loop if it is known, or a SCEVCouldNotCompute otherwise. 197 const SCEV *Exact; 198 199 /// Max - An expression indicating the least maximum backedge-taken 200 /// count of the loop that is known, or a SCEVCouldNotCompute. 201 const SCEV *Max; 202 203 /*implicit*/ BackedgeTakenInfo(const SCEV *exact) : 204 Exact(exact), Max(exact) {} 205 206 BackedgeTakenInfo(const SCEV *exact, const SCEV *max) : 207 Exact(exact), Max(max) {} 208 209 /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any 210 /// computed information, or whether it's all SCEVCouldNotCompute 211 /// values. 212 bool hasAnyInfo() const { 213 return !isa<SCEVCouldNotCompute>(Exact) || 214 !isa<SCEVCouldNotCompute>(Max); 215 } 216 }; 217 218 /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for 219 /// this function as they are computed. 220 std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts; 221 222 /// ConstantEvolutionLoopExitValue - This map contains entries for all of 223 /// the PHI instructions that we attempt to compute constant evolutions for. 224 /// This allows us to avoid potentially expensive recomputation of these 225 /// properties. An instruction maps to null if we are unable to compute its 226 /// exit value. 227 std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue; 228 229 /// ValuesAtScopes - This map contains entries for all the instructions 230 /// that we attempt to compute getSCEVAtScope information for without 231 /// using SCEV techniques, which can be expensive. 232 std::map<Instruction *, std::map<const Loop *, Constant *> > ValuesAtScopes; 233 234 /// createSCEV - We know that there is no SCEV for the specified value. 235 /// Analyze the expression. 236 const SCEV *createSCEV(Value *V); 237 238 /// createNodeForPHI - Provide the special handling we need to analyze PHI 239 /// SCEVs. 240 const SCEV *createNodeForPHI(PHINode *PN); 241 242 /// createNodeForGEP - Provide the special handling we need to analyze GEP 243 /// SCEVs. 244 const SCEV *createNodeForGEP(Operator *GEP); 245 246 /// ForgetSymbolicValue - This looks up computed SCEV values for all 247 /// instructions that depend on the given instruction and removes them from 248 /// the Scalars map if they reference SymName. This is used during PHI 249 /// resolution. 250 void ForgetSymbolicName(Instruction *I, const SCEV *SymName); 251 252 /// getBECount - Subtract the end and start values and divide by the step, 253 /// rounding up, to get the number of times the backedge is executed. Return 254 /// CouldNotCompute if an intermediate computation overflows. 255 const SCEV *getBECount(const SCEV *Start, 256 const SCEV *End, 257 const SCEV *Step); 258 259 /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given 260 /// loop, lazily computing new values if the loop hasn't been analyzed 261 /// yet. 262 const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L); 263 264 /// ComputeBackedgeTakenCount - Compute the number of times the specified 265 /// loop will iterate. 266 BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L); 267 268 /// ComputeBackedgeTakenCountFromExit - Compute the number of times the 269 /// backedge of the specified loop will execute if it exits via the 270 /// specified block. 271 BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L, 272 BasicBlock *ExitingBlock); 273 274 /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the 275 /// backedge of the specified loop will execute if its exit condition 276 /// were a conditional branch of ExitCond, TBB, and FBB. 277 BackedgeTakenInfo 278 ComputeBackedgeTakenCountFromExitCond(const Loop *L, 279 Value *ExitCond, 280 BasicBlock *TBB, 281 BasicBlock *FBB); 282 283 /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of 284 /// times the backedge of the specified loop will execute if its exit 285 /// condition were a conditional branch of the ICmpInst ExitCond, TBB, 286 /// and FBB. 287 BackedgeTakenInfo 288 ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L, 289 ICmpInst *ExitCond, 290 BasicBlock *TBB, 291 BasicBlock *FBB); 292 293 /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition 294 /// of 'icmp op load X, cst', try to see if we can compute the 295 /// backedge-taken count. 296 const SCEV * 297 ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI, 298 Constant *RHS, 299 const Loop *L, 300 ICmpInst::Predicate p); 301 302 /// ComputeBackedgeTakenCountExhaustively - If the trip is known to execute 303 /// a constant number of times (the condition evolves only from constants), 304 /// try to evaluate a few iterations of the loop until we get the exit 305 /// condition gets a value of ExitWhen (true or false). If we cannot 306 /// evaluate the backedge-taken count of the loop, return CouldNotCompute. 307 const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L, 308 Value *Cond, 309 bool ExitWhen); 310 311 /// HowFarToZero - Return the number of times a backedge comparing the 312 /// specified value to zero will execute. If not computable, return 313 /// CouldNotCompute. 314 const SCEV *HowFarToZero(const SCEV *V, const Loop *L); 315 316 /// HowFarToNonZero - Return the number of times a backedge checking the 317 /// specified value for nonzero will execute. If not computable, return 318 /// CouldNotCompute. 319 const SCEV *HowFarToNonZero(const SCEV *V, const Loop *L); 320 321 /// HowManyLessThans - Return the number of times a backedge containing the 322 /// specified less-than comparison will execute. If not computable, return 323 /// CouldNotCompute. isSigned specifies whether the less-than is signed. 324 BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS, 325 const Loop *L, bool isSigned); 326 327 /// getLoopPredecessor - If the given loop's header has exactly one unique 328 /// predecessor outside the loop, return it. Otherwise return null. 329 BasicBlock *getLoopPredecessor(const Loop *L); 330 331 /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB 332 /// (which may not be an immediate predecessor) which has exactly one 333 /// successor from which BB is reachable, or null if no such block is 334 /// found. 335 BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB); 336 337 /// isImpliedCond - Test whether the condition described by Pred, LHS, 338 /// and RHS is true whenever the given Cond value evaluates to true. 339 bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred, 340 const SCEV *LHS, const SCEV *RHS, 341 bool Inverse); 342 343 /// isImpliedCondOperands - Test whether the condition described by Pred, 344 /// LHS, and RHS is true whenever the condition desribed by Pred, FoundLHS, 345 /// and FoundRHS is true. 346 bool isImpliedCondOperands(ICmpInst::Predicate Pred, 347 const SCEV *LHS, const SCEV *RHS, 348 const SCEV *FoundLHS, const SCEV *FoundRHS); 349 350 /// isImpliedCondOperandsHelper - Test whether the condition described by 351 /// Pred, LHS, and RHS is true whenever the condition desribed by Pred, 352 /// FoundLHS, and FoundRHS is true. 353 bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, 354 const SCEV *LHS, const SCEV *RHS, 355 const SCEV *FoundLHS, const SCEV *FoundRHS); 356 357 /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is 358 /// in the header of its containing loop, we know the loop executes a 359 /// constant number of times, and the PHI node is just a recurrence 360 /// involving constants, fold it. 361 Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs, 362 const Loop *L); 363 364 public: 365 static char ID; // Pass identification, replacement for typeid 366 ScalarEvolution(); 367 368 LLVMContext &getContext() const { return F->getContext(); } 369 370 /// isSCEVable - Test if values of the given type are analyzable within 371 /// the SCEV framework. This primarily includes integer types, and it 372 /// can optionally include pointer types if the ScalarEvolution class 373 /// has access to target-specific information. 374 bool isSCEVable(const Type *Ty) const; 375 376 /// getTypeSizeInBits - Return the size in bits of the specified type, 377 /// for which isSCEVable must return true. 378 uint64_t getTypeSizeInBits(const Type *Ty) const; 379 380 /// getEffectiveSCEVType - Return a type with the same bitwidth as 381 /// the given type and which represents how SCEV will treat the given 382 /// type, for which isSCEVable must return true. For pointer types, 383 /// this is the pointer-sized integer type. 384 const Type *getEffectiveSCEVType(const Type *Ty) const; 385 386 /// getSCEV - Return a SCEV expression handle for the full generality of the 387 /// specified expression. 388 const SCEV *getSCEV(Value *V); 389 390 const SCEV *getConstant(ConstantInt *V); 391 const SCEV *getConstant(const APInt& Val); 392 const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false); 393 const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty); 394 const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty); 395 const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty); 396 const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty); 397 const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops); 398 const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS) { 399 SmallVector<const SCEV *, 2> Ops; 400 Ops.push_back(LHS); 401 Ops.push_back(RHS); 402 return getAddExpr(Ops); 403 } 404 const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1, 405 const SCEV *Op2) { 406 SmallVector<const SCEV *, 3> Ops; 407 Ops.push_back(Op0); 408 Ops.push_back(Op1); 409 Ops.push_back(Op2); 410 return getAddExpr(Ops); 411 } 412 const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops); 413 const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS) { 414 SmallVector<const SCEV *, 2> Ops; 415 Ops.push_back(LHS); 416 Ops.push_back(RHS); 417 return getMulExpr(Ops); 418 } 419 const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS); 420 const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step, 421 const Loop *L); 422 const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, 423 const Loop *L); 424 const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands, 425 const Loop *L) { 426 SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end()); 427 return getAddRecExpr(NewOp, L); 428 } 429 const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS); 430 const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands); 431 const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS); 432 const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands); 433 const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS); 434 const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS); 435 const SCEV *getUnknown(Value *V); 436 const SCEV *getCouldNotCompute(); 437 438 /// getNegativeSCEV - Return the SCEV object corresponding to -V. 439 /// 440 const SCEV *getNegativeSCEV(const SCEV *V); 441 442 /// getNotSCEV - Return the SCEV object corresponding to ~V. 443 /// 444 const SCEV *getNotSCEV(const SCEV *V); 445 446 /// getMinusSCEV - Return LHS-RHS. 447 /// 448 const SCEV *getMinusSCEV(const SCEV *LHS, 449 const SCEV *RHS); 450 451 /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion 452 /// of the input value to the specified type. If the type must be 453 /// extended, it is zero extended. 454 const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty); 455 456 /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion 457 /// of the input value to the specified type. If the type must be 458 /// extended, it is sign extended. 459 const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty); 460 461 /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of 462 /// the input value to the specified type. If the type must be extended, 463 /// it is zero extended. The conversion must not be narrowing. 464 const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty); 465 466 /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of 467 /// the input value to the specified type. If the type must be extended, 468 /// it is sign extended. The conversion must not be narrowing. 469 const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty); 470 471 /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of 472 /// the input value to the specified type. If the type must be extended, 473 /// it is extended with unspecified bits. The conversion must not be 474 /// narrowing. 475 const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty); 476 477 /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the 478 /// input value to the specified type. The conversion must not be 479 /// widening. 480 const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty); 481 482 /// getIntegerSCEV - Given a SCEVable type, create a constant for the 483 /// specified signed integer value and return a SCEV for the constant. 484 const SCEV *getIntegerSCEV(int Val, const Type *Ty); 485 486 /// getUMaxFromMismatchedTypes - Promote the operands to the wider of 487 /// the types using zero-extension, and then perform a umax operation 488 /// with them. 489 const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS, 490 const SCEV *RHS); 491 492 /// getUMinFromMismatchedTypes - Promote the operands to the wider of 493 /// the types using zero-extension, and then perform a umin operation 494 /// with them. 495 const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS, 496 const SCEV *RHS); 497 498 /// getSCEVAtScope - Return a SCEV expression handle for the specified value 499 /// at the specified scope in the program. The L value specifies a loop 500 /// nest to evaluate the expression at, where null is the top-level or a 501 /// specified loop is immediately inside of the loop. 502 /// 503 /// This method can be used to compute the exit value for a variable defined 504 /// in a loop by querying what the value will hold in the parent loop. 505 /// 506 /// In the case that a relevant loop exit value cannot be computed, the 507 /// original value V is returned. 508 const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L); 509 510 /// getSCEVAtScope - This is a convenience function which does 511 /// getSCEVAtScope(getSCEV(V), L). 512 const SCEV *getSCEVAtScope(Value *V, const Loop *L); 513 514 /// isLoopGuardedByCond - Test whether entry to the loop is protected by 515 /// a conditional between LHS and RHS. This is used to help avoid max 516 /// expressions in loop trip counts, and to eliminate casts. 517 bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, 518 const SCEV *LHS, const SCEV *RHS); 519 520 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is 521 /// protected by a conditional between LHS and RHS. This is used to 522 /// to eliminate casts. 523 bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, 524 const SCEV *LHS, const SCEV *RHS); 525 526 /// getBackedgeTakenCount - If the specified loop has a predictable 527 /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute 528 /// object. The backedge-taken count is the number of times the loop header 529 /// will be branched to from within the loop. This is one less than the 530 /// trip count of the loop, since it doesn't count the first iteration, 531 /// when the header is branched to from outside the loop. 532 /// 533 /// Note that it is not valid to call this method on a loop without a 534 /// loop-invariant backedge-taken count (see 535 /// hasLoopInvariantBackedgeTakenCount). 536 /// 537 const SCEV *getBackedgeTakenCount(const Loop *L); 538 539 /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except 540 /// return the least SCEV value that is known never to be less than the 541 /// actual backedge taken count. 542 const SCEV *getMaxBackedgeTakenCount(const Loop *L); 543 544 /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop 545 /// has an analyzable loop-invariant backedge-taken count. 546 bool hasLoopInvariantBackedgeTakenCount(const Loop *L); 547 548 /// forgetLoopBackedgeTakenCount - This method should be called by the 549 /// client when it has changed a loop in a way that may effect 550 /// ScalarEvolution's ability to compute a trip count, or if the loop 551 /// is deleted. 552 void forgetLoopBackedgeTakenCount(const Loop *L); 553 554 /// GetMinTrailingZeros - Determine the minimum number of zero bits that S 555 /// is guaranteed to end in (at every loop iteration). It is, at the same 556 /// time, the minimum number of times S is divisible by 2. For example, 557 /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the 558 /// bitwidth of S. 559 uint32_t GetMinTrailingZeros(const SCEV *S); 560 561 /// getUnsignedRange - Determine the unsigned range for a particular SCEV. 562 /// 563 ConstantRange getUnsignedRange(const SCEV *S); 564 565 /// getSignedRange - Determine the signed range for a particular SCEV. 566 /// 567 ConstantRange getSignedRange(const SCEV *S); 568 569 /// isKnownNegative - Test if the given expression is known to be negative. 570 /// 571 bool isKnownNegative(const SCEV *S); 572 573 /// isKnownPositive - Test if the given expression is known to be positive. 574 /// 575 bool isKnownPositive(const SCEV *S); 576 577 /// isKnownNonNegative - Test if the given expression is known to be 578 /// non-negative. 579 /// 580 bool isKnownNonNegative(const SCEV *S); 581 582 /// isKnownNonPositive - Test if the given expression is known to be 583 /// non-positive. 584 /// 585 bool isKnownNonPositive(const SCEV *S); 586 587 /// isKnownNonZero - Test if the given expression is known to be 588 /// non-zero. 589 /// 590 bool isKnownNonZero(const SCEV *S); 591 592 /// isKnownNonZero - Test if the given expression is known to satisfy 593 /// the condition described by Pred, LHS, and RHS. 594 /// 595 bool isKnownPredicate(ICmpInst::Predicate Pred, 596 const SCEV *LHS, const SCEV *RHS); 597 598 virtual bool runOnFunction(Function &F); 599 virtual void releaseMemory(); 600 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 601 void print(raw_ostream &OS, const Module* = 0) const; 602 virtual void print(std::ostream &OS, const Module* = 0) const; 603 void print(std::ostream *OS, const Module* M = 0) const { 604 if (OS) print(*OS, M); 605 } 606 607 private: 608 FoldingSet<SCEV> UniqueSCEVs; 609 BumpPtrAllocator SCEVAllocator; 610 }; 611} 612 613#endif 614