ScalarEvolution.h revision c40f17b08774c2dcc5787fd83241e3c64ba82974
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/Function.h" 27#include "llvm/Support/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" 33#include <iosfwd> 34#include <map> 35 36namespace llvm { 37 class APInt; 38 class Constant; 39 class ConstantInt; 40 class DominatorTree; 41 class Type; 42 class ScalarEvolution; 43 class TargetData; 44 class LLVMContext; 45 class Loop; 46 class LoopInfo; 47 class Operator; 48 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 51 /// directly. 52 /// 53 class SCEV : public FastFoldingSetNode { 54 // The SCEV baseclass this node corresponds to 55 const unsigned short SCEVType; 56 57 protected: 58 /// SubclassData - This field is initialized to zero and may be used in 59 /// subclasses to store miscelaneous information. 60 unsigned short SubclassData; 61 62 private: 63 SCEV(const SCEV &); // DO NOT IMPLEMENT 64 void operator=(const SCEV &); // DO NOT IMPLEMENT 65 protected: 66 virtual ~SCEV(); 67 public: 68 explicit SCEV(const FoldingSetNodeID &ID, unsigned SCEVTy) : 69 FastFoldingSetNode(ID), SCEVType(SCEVTy), SubclassData(0) {} 70 71 unsigned getSCEVType() const { return SCEVType; } 72 73 /// isLoopInvariant - Return true if the value of this SCEV is unchanging in 74 /// the specified loop. 75 virtual bool isLoopInvariant(const Loop *L) const = 0; 76 77 /// hasComputableLoopEvolution - Return true if this SCEV changes value in a 78 /// known way in the specified loop. This property being true implies that 79 /// the value is variant in the loop AND that we can emit an expression to 80 /// compute the value of the expression at any particular loop iteration. 81 virtual bool hasComputableLoopEvolution(const Loop *L) const = 0; 82 83 /// getType - Return the LLVM type of this SCEV expression. 84 /// 85 virtual const Type *getType() const = 0; 86 87 /// isZero - Return true if the expression is a constant zero. 88 /// 89 bool isZero() const; 90 91 /// isOne - Return true if the expression is a constant one. 92 /// 93 bool isOne() const; 94 95 /// isAllOnesValue - Return true if the expression is a constant 96 /// all-ones value. 97 /// 98 bool isAllOnesValue() const; 99 100 /// hasOperand - Test whether this SCEV has Op as a direct or 101 /// indirect operand. 102 virtual bool hasOperand(const SCEV *Op) const = 0; 103 104 /// dominates - Return true if elements that makes up this SCEV dominates 105 /// the specified basic block. 106 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const = 0; 107 108 /// print - Print out the internal representation of this scalar to the 109 /// specified stream. This should really only be used for debugging 110 /// purposes. 111 virtual void print(raw_ostream &OS) const = 0; 112 void print(std::ostream &OS) const; 113 void print(std::ostream *OS) const { if (OS) print(*OS); } 114 115 /// dump - This method is used for debugging. 116 /// 117 void dump() const; 118 }; 119 120 inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) { 121 S.print(OS); 122 return OS; 123 } 124 125 inline std::ostream &operator<<(std::ostream &OS, const SCEV &S) { 126 S.print(OS); 127 return OS; 128 } 129 130 /// SCEVCouldNotCompute - An object of this class is returned by queries that 131 /// could not be answered. For example, if you ask for the number of 132 /// iterations of a linked-list traversal loop, you will get one of these. 133 /// None of the standard SCEV operations are valid on this class, it is just a 134 /// marker. 135 struct SCEVCouldNotCompute : public SCEV { 136 SCEVCouldNotCompute(); 137 138 // None of these methods are valid for this object. 139 virtual bool isLoopInvariant(const Loop *L) const; 140 virtual const Type *getType() const; 141 virtual bool hasComputableLoopEvolution(const Loop *L) const; 142 virtual void print(raw_ostream &OS) const; 143 virtual bool hasOperand(const SCEV *Op) const; 144 145 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const { 146 return true; 147 } 148 149 /// 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); 152 }; 153 154 /// 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. 157 /// 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 { 162 ScalarEvolution *SE; 163 virtual void deleted(); 164 virtual void allUsesReplacedWith(Value *New); 165 public: 166 SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0); 167 }; 168 169 friend class SCEVCallbackVH; 170 friend struct SCEVExpander; 171 172 /// F - The function we are analyzing. 173 /// 174 Function *F; 175 176 /// LI - The loop information for the function we are currently analyzing. 177 /// 178 LoopInfo *LI; 179 180 /// TD - The target data information for the target we are targetting. 181 /// 182 TargetData *TD; 183 184 /// CouldNotCompute - This SCEV is used to represent unknown trip 185 /// counts and things. 186 SCEVCouldNotCompute CouldNotCompute; 187 188 /// Scalars - This is a cache of the scalars we have analyzed so far. 189 /// 190 std::map<SCEVCallbackVH, const SCEV *> Scalars; 191 192 /// BackedgeTakenInfo - Information about the backedge-taken count 193 /// of a loop. This currently inclues an exact count and a maximum count. 194 /// 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. 198 const SCEV *Exact; 199 200 /// Max - An expression indicating the least maximum backedge-taken 201 /// count of the loop that is known, or a SCEVCouldNotCompute. 202 const SCEV *Max; 203 204 /*implicit*/ BackedgeTakenInfo(const SCEV *exact) : 205 Exact(exact), Max(exact) {} 206 207 BackedgeTakenInfo(const SCEV *exact, const SCEV *max) : 208 Exact(exact), Max(max) {} 209 210 /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any 211 /// computed information, or whether it's all SCEVCouldNotCompute 212 /// values. 213 bool hasAnyInfo() const { 214 return !isa<SCEVCouldNotCompute>(Exact) || 215 !isa<SCEVCouldNotCompute>(Max); 216 } 217 }; 218 219 /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for 220 /// this function as they are computed. 221 std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts; 222 223 /// 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 227 /// exit value. 228 std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue; 229 230 /// ValuesAtScopes - This map contains entries for all the instructions 231 /// that we attempt to compute getSCEVAtScope information for without 232 /// using SCEV techniques, which can be expensive. 233 std::map<Instruction *, std::map<const Loop *, Constant *> > ValuesAtScopes; 234 235 /// createSCEV - We know that there is no SCEV for the specified value. 236 /// Analyze the expression. 237 const SCEV *createSCEV(Value *V); 238 239 /// createNodeForPHI - Provide the special handling we need to analyze PHI 240 /// SCEVs. 241 const SCEV *createNodeForPHI(PHINode *PN); 242 243 /// createNodeForGEP - Provide the special handling we need to analyze GEP 244 /// SCEVs. 245 const SCEV *createNodeForGEP(Operator *GEP); 246 247 /// ForgetSymbolicValue - This looks up computed SCEV values for all 248 /// instructions that depend on the given instruction and removes them from 249 /// the Scalars map if they reference SymName. This is used during PHI 250 /// resolution. 251 void ForgetSymbolicName(Instruction *I, const SCEV *SymName); 252 253 /// getBECount - Subtract the end and start values and divide by the step, 254 /// rounding up, to get the number of times the backedge is executed. Return 255 /// CouldNotCompute if an intermediate computation overflows. 256 const SCEV *getBECount(const SCEV *Start, 257 const SCEV *End, 258 const SCEV *Step); 259 260 /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given 261 /// loop, lazily computing new values if the loop hasn't been analyzed 262 /// yet. 263 const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L); 264 265 /// ComputeBackedgeTakenCount - Compute the number of times the specified 266 /// loop will iterate. 267 BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L); 268 269 /// ComputeBackedgeTakenCountFromExit - Compute the number of times the 270 /// backedge of the specified loop will execute if it exits via the 271 /// specified block. 272 BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L, 273 BasicBlock *ExitingBlock); 274 275 /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the 276 /// backedge of the specified loop will execute if its exit condition 277 /// were a conditional branch of ExitCond, TBB, and FBB. 278 BackedgeTakenInfo 279 ComputeBackedgeTakenCountFromExitCond(const Loop *L, 280 Value *ExitCond, 281 BasicBlock *TBB, 282 BasicBlock *FBB); 283 284 /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of 285 /// times the backedge of the specified loop will execute if its exit 286 /// condition were a conditional branch of the ICmpInst ExitCond, TBB, 287 /// and FBB. 288 BackedgeTakenInfo 289 ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L, 290 ICmpInst *ExitCond, 291 BasicBlock *TBB, 292 BasicBlock *FBB); 293 294 /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition 295 /// of 'icmp op load X, cst', try to see if we can compute the 296 /// backedge-taken count. 297 const SCEV * 298 ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI, 299 Constant *RHS, 300 const Loop *L, 301 ICmpInst::Predicate p); 302 303 /// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute 304 /// a constant number of times (the condition evolves only from constants), 305 /// try to evaluate a few iterations of the loop until we get the exit 306 /// condition gets a value of ExitWhen (true or false). If we cannot 307 /// evaluate the backedge-taken count of the loop, return CouldNotCompute. 308 const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L, 309 Value *Cond, 310 bool ExitWhen); 311 312 /// HowFarToZero - Return the number of times a backedge comparing the 313 /// specified value to zero will execute. If not computable, return 314 /// CouldNotCompute. 315 const SCEV *HowFarToZero(const SCEV *V, const Loop *L); 316 317 /// HowFarToNonZero - Return the number of times a backedge checking the 318 /// specified value for nonzero will execute. If not computable, return 319 /// CouldNotCompute. 320 const SCEV *HowFarToNonZero(const SCEV *V, const Loop *L); 321 322 /// HowManyLessThans - Return the number of times a backedge containing the 323 /// specified less-than comparison will execute. If not computable, return 324 /// CouldNotCompute. isSigned specifies whether the less-than is signed. 325 BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS, 326 const Loop *L, bool isSigned); 327 328 /// getLoopPredecessor - If the given loop's header has exactly one unique 329 /// predecessor outside the loop, return it. Otherwise return null. 330 BasicBlock *getLoopPredecessor(const Loop *L); 331 332 /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB 333 /// (which may not be an immediate predecessor) which has exactly one 334 /// successor from which BB is reachable, or null if no such block is 335 /// found. 336 BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB); 337 338 /// isImpliedCond - Test whether the condition described by Pred, LHS, 339 /// and RHS is true whenever the given Cond value evaluates to true. 340 bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred, 341 const SCEV *LHS, const SCEV *RHS, 342 bool Inverse); 343 344 /// isImpliedCondOperands - Test whether the condition described by Pred, 345 /// LHS, and RHS is true whenever the condition desribed by Pred, FoundLHS, 346 /// and FoundRHS is true. 347 bool isImpliedCondOperands(ICmpInst::Predicate Pred, 348 const SCEV *LHS, const SCEV *RHS, 349 const SCEV *FoundLHS, const SCEV *FoundRHS); 350 351 /// isImpliedCondOperandsHelper - Test whether the condition described by 352 /// Pred, LHS, and RHS is true whenever the condition desribed by Pred, 353 /// FoundLHS, and FoundRHS is true. 354 bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, 355 const SCEV *LHS, const SCEV *RHS, 356 const SCEV *FoundLHS, const SCEV *FoundRHS); 357 358 /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is 359 /// in the header of its containing loop, we know the loop executes a 360 /// constant number of times, and the PHI node is just a recurrence 361 /// involving constants, fold it. 362 Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs, 363 const Loop *L); 364 365 public: 366 static char ID; // Pass identification, replacement for typeid 367 ScalarEvolution(); 368 369 LLVMContext &getContext() const { return F->getContext(); } 370 371 /// isSCEVable - Test if values of the given type are analyzable within 372 /// the SCEV framework. This primarily includes integer types, and it 373 /// can optionally include pointer types if the ScalarEvolution class 374 /// has access to target-specific information. 375 bool isSCEVable(const Type *Ty) const; 376 377 /// getTypeSizeInBits - Return the size in bits of the specified type, 378 /// for which isSCEVable must return true. 379 uint64_t getTypeSizeInBits(const Type *Ty) const; 380 381 /// getEffectiveSCEVType - Return a type with the same bitwidth as 382 /// the given type and which represents how SCEV will treat the given 383 /// type, for which isSCEVable must return true. For pointer types, 384 /// this is the pointer-sized integer type. 385 const Type *getEffectiveSCEVType(const Type *Ty) const; 386 387 /// getSCEV - Return a SCEV expression handle for the full generality of the 388 /// specified expression. 389 const SCEV *getSCEV(Value *V); 390 391 const SCEV *getConstant(ConstantInt *V); 392 const SCEV *getConstant(const APInt& Val); 393 const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false); 394 const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty); 395 const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty); 396 const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty); 397 const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty); 398 const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops); 399 const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS) { 400 SmallVector<const SCEV *, 2> Ops; 401 Ops.push_back(LHS); 402 Ops.push_back(RHS); 403 return getAddExpr(Ops); 404 } 405 const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1, 406 const SCEV *Op2) { 407 SmallVector<const SCEV *, 3> Ops; 408 Ops.push_back(Op0); 409 Ops.push_back(Op1); 410 Ops.push_back(Op2); 411 return getAddExpr(Ops); 412 } 413 const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops); 414 const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS) { 415 SmallVector<const SCEV *, 2> Ops; 416 Ops.push_back(LHS); 417 Ops.push_back(RHS); 418 return getMulExpr(Ops); 419 } 420 const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS); 421 const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step, 422 const Loop *L); 423 const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, 424 const Loop *L); 425 const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands, 426 const Loop *L) { 427 SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end()); 428 return getAddRecExpr(NewOp, L); 429 } 430 const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS); 431 const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands); 432 const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS); 433 const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands); 434 const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS); 435 const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS); 436 const SCEV *getFieldOffsetExpr(const StructType *STy, unsigned FieldNo); 437 const SCEV *getAllocSizeExpr(const Type *AllocTy); 438 const SCEV *getUnknown(Value *V); 439 const SCEV *getCouldNotCompute(); 440 441 /// getNegativeSCEV - Return the SCEV object corresponding to -V. 442 /// 443 const SCEV *getNegativeSCEV(const SCEV *V); 444 445 /// getNotSCEV - Return the SCEV object corresponding to ~V. 446 /// 447 const SCEV *getNotSCEV(const SCEV *V); 448 449 /// getMinusSCEV - Return LHS-RHS. 450 /// 451 const SCEV *getMinusSCEV(const SCEV *LHS, 452 const SCEV *RHS); 453 454 /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion 455 /// of the input value to the specified type. If the type must be 456 /// extended, it is zero extended. 457 const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty); 458 459 /// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion 460 /// of the input value to the specified type. If the type must be 461 /// extended, it is sign extended. 462 const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty); 463 464 /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of 465 /// the input value to the specified type. If the type must be extended, 466 /// it is zero extended. The conversion must not be narrowing. 467 const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty); 468 469 /// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of 470 /// the input value to the specified type. If the type must be extended, 471 /// it is sign extended. The conversion must not be narrowing. 472 const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty); 473 474 /// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of 475 /// the input value to the specified type. If the type must be extended, 476 /// it is extended with unspecified bits. The conversion must not be 477 /// narrowing. 478 const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty); 479 480 /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the 481 /// input value to the specified type. The conversion must not be 482 /// widening. 483 const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty); 484 485 /// getIntegerSCEV - Given a SCEVable type, create a constant for the 486 /// specified signed integer value and return a SCEV for the constant. 487 const SCEV *getIntegerSCEV(int Val, const Type *Ty); 488 489 /// getUMaxFromMismatchedTypes - Promote the operands to the wider of 490 /// the types using zero-extension, and then perform a umax operation 491 /// with them. 492 const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS, 493 const SCEV *RHS); 494 495 /// getUMinFromMismatchedTypes - Promote the operands to the wider of 496 /// the types using zero-extension, and then perform a umin operation 497 /// with them. 498 const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS, 499 const SCEV *RHS); 500 501 /// getSCEVAtScope - Return a SCEV expression handle for the specified value 502 /// at the specified scope in the program. The L value specifies a loop 503 /// nest to evaluate the expression at, where null is the top-level or a 504 /// specified loop is immediately inside of the loop. 505 /// 506 /// This method can be used to compute the exit value for a variable defined 507 /// in a loop by querying what the value will hold in the parent loop. 508 /// 509 /// In the case that a relevant loop exit value cannot be computed, the 510 /// original value V is returned. 511 const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L); 512 513 /// getSCEVAtScope - This is a convenience function which does 514 /// getSCEVAtScope(getSCEV(V), L). 515 const SCEV *getSCEVAtScope(Value *V, const Loop *L); 516 517 /// isLoopGuardedByCond - Test whether entry to the loop is protected by 518 /// a conditional between LHS and RHS. This is used to help avoid max 519 /// expressions in loop trip counts, and to eliminate casts. 520 bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, 521 const SCEV *LHS, const SCEV *RHS); 522 523 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is 524 /// protected by a conditional between LHS and RHS. This is used to 525 /// to eliminate casts. 526 bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, 527 const SCEV *LHS, const SCEV *RHS); 528 529 /// getBackedgeTakenCount - If the specified loop has a predictable 530 /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute 531 /// object. The backedge-taken count is the number of times the loop header 532 /// will be branched to from within the loop. This is one less than the 533 /// trip count of the loop, since it doesn't count the first iteration, 534 /// when the header is branched to from outside the loop. 535 /// 536 /// Note that it is not valid to call this method on a loop without a 537 /// loop-invariant backedge-taken count (see 538 /// hasLoopInvariantBackedgeTakenCount). 539 /// 540 const SCEV *getBackedgeTakenCount(const Loop *L); 541 542 /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except 543 /// return the least SCEV value that is known never to be less than the 544 /// actual backedge taken count. 545 const SCEV *getMaxBackedgeTakenCount(const Loop *L); 546 547 /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop 548 /// has an analyzable loop-invariant backedge-taken count. 549 bool hasLoopInvariantBackedgeTakenCount(const Loop *L); 550 551 /// forgetLoopBackedgeTakenCount - This method should be called by the 552 /// client when it has changed a loop in a way that may effect 553 /// ScalarEvolution's ability to compute a trip count, or if the loop 554 /// is deleted. 555 void forgetLoopBackedgeTakenCount(const Loop *L); 556 557 /// GetMinTrailingZeros - Determine the minimum number of zero bits that S 558 /// is guaranteed to end in (at every loop iteration). It is, at the same 559 /// time, the minimum number of times S is divisible by 2. For example, 560 /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the 561 /// bitwidth of S. 562 uint32_t GetMinTrailingZeros(const SCEV *S); 563 564 /// getUnsignedRange - Determine the unsigned range for a particular SCEV. 565 /// 566 ConstantRange getUnsignedRange(const SCEV *S); 567 568 /// getSignedRange - Determine the signed range for a particular SCEV. 569 /// 570 ConstantRange getSignedRange(const SCEV *S); 571 572 /// isKnownNegative - Test if the given expression is known to be negative. 573 /// 574 bool isKnownNegative(const SCEV *S); 575 576 /// isKnownPositive - Test if the given expression is known to be positive. 577 /// 578 bool isKnownPositive(const SCEV *S); 579 580 /// isKnownNonNegative - Test if the given expression is known to be 581 /// non-negative. 582 /// 583 bool isKnownNonNegative(const SCEV *S); 584 585 /// isKnownNonPositive - Test if the given expression is known to be 586 /// non-positive. 587 /// 588 bool isKnownNonPositive(const SCEV *S); 589 590 /// isKnownNonZero - Test if the given expression is known to be 591 /// non-zero. 592 /// 593 bool isKnownNonZero(const SCEV *S); 594 595 /// isKnownNonZero - Test if the given expression is known to satisfy 596 /// the condition described by Pred, LHS, and RHS. 597 /// 598 bool isKnownPredicate(ICmpInst::Predicate Pred, 599 const SCEV *LHS, const SCEV *RHS); 600 601 virtual bool runOnFunction(Function &F); 602 virtual void releaseMemory(); 603 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 604 void print(raw_ostream &OS, const Module* = 0) const; 605 virtual void print(std::ostream &OS, const Module* = 0) const; 606 void print(std::ostream *OS, const Module* M = 0) const { 607 if (OS) print(*OS, M); 608 } 609 610 private: 611 FoldingSet<SCEV> UniqueSCEVs; 612 BumpPtrAllocator SCEVAllocator; 613 }; 614} 615 616#endif 617