ScalarEvolution.h revision 9661c13c37d017df6f91a399c0160b82e8a6c39f
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 <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; 111 112 /// dump - This method is used for debugging. 113 /// 114 void dump() const; 115 }; 116 117 inline raw_ostream &operator<<(raw_ostream &OS, const SCEV &S) { 118 S.print(OS); 119 return OS; 120 } 121 122 /// SCEVCouldNotCompute - An object of this class is returned by queries that 123 /// could not be answered. For example, if you ask for the number of 124 /// iterations of a linked-list traversal loop, you will get one of these. 125 /// None of the standard SCEV operations are valid on this class, it is just a 126 /// marker. 127 struct SCEVCouldNotCompute : public SCEV { 128 SCEVCouldNotCompute(); 129 130 // None of these methods are valid for this object. 131 virtual bool isLoopInvariant(const Loop *L) const; 132 virtual const Type *getType() const; 133 virtual bool hasComputableLoopEvolution(const Loop *L) const; 134 virtual void print(raw_ostream &OS) const; 135 virtual bool hasOperand(const SCEV *Op) const; 136 137 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const { 138 return true; 139 } 140 141 /// Methods for support type inquiry through isa, cast, and dyn_cast: 142 static inline bool classof(const SCEVCouldNotCompute *S) { return true; } 143 static bool classof(const SCEV *S); 144 }; 145 146 /// ScalarEvolution - This class is the main scalar evolution driver. Because 147 /// client code (intentionally) can't do much with the SCEV objects directly, 148 /// they must ask this class for services. 149 /// 150 class ScalarEvolution : public FunctionPass { 151 /// SCEVCallbackVH - A CallbackVH to arrange for ScalarEvolution to be 152 /// notified whenever a Value is deleted. 153 class SCEVCallbackVH : public CallbackVH { 154 ScalarEvolution *SE; 155 virtual void deleted(); 156 virtual void allUsesReplacedWith(Value *New); 157 public: 158 SCEVCallbackVH(Value *V, ScalarEvolution *SE = 0); 159 }; 160 161 friend class SCEVCallbackVH; 162 friend struct SCEVExpander; 163 164 /// F - The function we are analyzing. 165 /// 166 Function *F; 167 168 /// LI - The loop information for the function we are currently analyzing. 169 /// 170 LoopInfo *LI; 171 172 /// TD - The target data information for the target we are targetting. 173 /// 174 TargetData *TD; 175 176 /// CouldNotCompute - This SCEV is used to represent unknown trip 177 /// counts and things. 178 SCEVCouldNotCompute CouldNotCompute; 179 180 /// Scalars - This is a cache of the scalars we have analyzed so far. 181 /// 182 std::map<SCEVCallbackVH, const SCEV *> Scalars; 183 184 /// BackedgeTakenInfo - Information about the backedge-taken count 185 /// of a loop. This currently inclues an exact count and a maximum count. 186 /// 187 struct BackedgeTakenInfo { 188 /// Exact - An expression indicating the exact backedge-taken count of 189 /// the loop if it is known, or a SCEVCouldNotCompute otherwise. 190 const SCEV *Exact; 191 192 /// Max - An expression indicating the least maximum backedge-taken 193 /// count of the loop that is known, or a SCEVCouldNotCompute. 194 const SCEV *Max; 195 196 /*implicit*/ BackedgeTakenInfo(const SCEV *exact) : 197 Exact(exact), Max(exact) {} 198 199 BackedgeTakenInfo(const SCEV *exact, const SCEV *max) : 200 Exact(exact), Max(max) {} 201 202 /// hasAnyInfo - Test whether this BackedgeTakenInfo contains any 203 /// computed information, or whether it's all SCEVCouldNotCompute 204 /// values. 205 bool hasAnyInfo() const { 206 return !isa<SCEVCouldNotCompute>(Exact) || 207 !isa<SCEVCouldNotCompute>(Max); 208 } 209 }; 210 211 /// BackedgeTakenCounts - Cache the backedge-taken count of the loops for 212 /// this function as they are computed. 213 std::map<const Loop*, BackedgeTakenInfo> BackedgeTakenCounts; 214 215 /// ConstantEvolutionLoopExitValue - This map contains entries for all of 216 /// the PHI instructions that we attempt to compute constant evolutions for. 217 /// This allows us to avoid potentially expensive recomputation of these 218 /// properties. An instruction maps to null if we are unable to compute its 219 /// exit value. 220 std::map<PHINode*, Constant*> ConstantEvolutionLoopExitValue; 221 222 /// ValuesAtScopes - This map contains entries for all the instructions 223 /// that we attempt to compute getSCEVAtScope information for without 224 /// using SCEV techniques, which can be expensive. 225 std::map<Instruction *, std::map<const Loop *, Constant *> > ValuesAtScopes; 226 227 /// createSCEV - We know that there is no SCEV for the specified value. 228 /// Analyze the expression. 229 const SCEV *createSCEV(Value *V); 230 231 /// createNodeForPHI - Provide the special handling we need to analyze PHI 232 /// SCEVs. 233 const SCEV *createNodeForPHI(PHINode *PN); 234 235 /// createNodeForGEP - Provide the special handling we need to analyze GEP 236 /// SCEVs. 237 const SCEV *createNodeForGEP(Operator *GEP); 238 239 /// ForgetSymbolicValue - This looks up computed SCEV values for all 240 /// instructions that depend on the given instruction and removes them from 241 /// the Scalars map if they reference SymName. This is used during PHI 242 /// resolution. 243 void ForgetSymbolicName(Instruction *I, const SCEV *SymName); 244 245 /// getBECount - Subtract the end and start values and divide by the step, 246 /// rounding up, to get the number of times the backedge is executed. Return 247 /// CouldNotCompute if an intermediate computation overflows. 248 const SCEV *getBECount(const SCEV *Start, 249 const SCEV *End, 250 const SCEV *Step); 251 252 /// getBackedgeTakenInfo - Return the BackedgeTakenInfo for the given 253 /// loop, lazily computing new values if the loop hasn't been analyzed 254 /// yet. 255 const BackedgeTakenInfo &getBackedgeTakenInfo(const Loop *L); 256 257 /// ComputeBackedgeTakenCount - Compute the number of times the specified 258 /// loop will iterate. 259 BackedgeTakenInfo ComputeBackedgeTakenCount(const Loop *L); 260 261 /// ComputeBackedgeTakenCountFromExit - Compute the number of times the 262 /// backedge of the specified loop will execute if it exits via the 263 /// specified block. 264 BackedgeTakenInfo ComputeBackedgeTakenCountFromExit(const Loop *L, 265 BasicBlock *ExitingBlock); 266 267 /// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the 268 /// backedge of the specified loop will execute if its exit condition 269 /// were a conditional branch of ExitCond, TBB, and FBB. 270 BackedgeTakenInfo 271 ComputeBackedgeTakenCountFromExitCond(const Loop *L, 272 Value *ExitCond, 273 BasicBlock *TBB, 274 BasicBlock *FBB); 275 276 /// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of 277 /// times the backedge of the specified loop will execute if its exit 278 /// condition were a conditional branch of the ICmpInst ExitCond, TBB, 279 /// and FBB. 280 BackedgeTakenInfo 281 ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L, 282 ICmpInst *ExitCond, 283 BasicBlock *TBB, 284 BasicBlock *FBB); 285 286 /// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition 287 /// of 'icmp op load X, cst', try to see if we can compute the 288 /// backedge-taken count. 289 const SCEV * 290 ComputeLoadConstantCompareBackedgeTakenCount(LoadInst *LI, 291 Constant *RHS, 292 const Loop *L, 293 ICmpInst::Predicate p); 294 295 /// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute 296 /// a constant number of times (the condition evolves only from constants), 297 /// try to evaluate a few iterations of the loop until we get the exit 298 /// condition gets a value of ExitWhen (true or false). If we cannot 299 /// evaluate the backedge-taken count of the loop, return CouldNotCompute. 300 const SCEV *ComputeBackedgeTakenCountExhaustively(const Loop *L, 301 Value *Cond, 302 bool ExitWhen); 303 304 /// HowFarToZero - Return the number of times a backedge comparing the 305 /// specified value to zero will execute. If not computable, return 306 /// CouldNotCompute. 307 const SCEV *HowFarToZero(const SCEV *V, const Loop *L); 308 309 /// HowFarToNonZero - Return the number of times a backedge checking the 310 /// specified value for nonzero will execute. If not computable, return 311 /// CouldNotCompute. 312 const SCEV *HowFarToNonZero(const SCEV *V, const Loop *L); 313 314 /// HowManyLessThans - Return the number of times a backedge containing the 315 /// specified less-than comparison will execute. If not computable, return 316 /// CouldNotCompute. isSigned specifies whether the less-than is signed. 317 BackedgeTakenInfo HowManyLessThans(const SCEV *LHS, const SCEV *RHS, 318 const Loop *L, bool isSigned); 319 320 /// getLoopPredecessor - If the given loop's header has exactly one unique 321 /// predecessor outside the loop, return it. Otherwise return null. 322 BasicBlock *getLoopPredecessor(const Loop *L); 323 324 /// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB 325 /// (which may not be an immediate predecessor) which has exactly one 326 /// successor from which BB is reachable, or null if no such block is 327 /// found. 328 BasicBlock* getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB); 329 330 /// isImpliedCond - Test whether the condition described by Pred, LHS, 331 /// and RHS is true whenever the given Cond value evaluates to true. 332 bool isImpliedCond(Value *Cond, ICmpInst::Predicate Pred, 333 const SCEV *LHS, const SCEV *RHS, 334 bool Inverse); 335 336 /// isImpliedCondOperands - Test whether the condition described by Pred, 337 /// LHS, and RHS is true whenever the condition desribed by Pred, FoundLHS, 338 /// and FoundRHS is true. 339 bool isImpliedCondOperands(ICmpInst::Predicate Pred, 340 const SCEV *LHS, const SCEV *RHS, 341 const SCEV *FoundLHS, const SCEV *FoundRHS); 342 343 /// isImpliedCondOperandsHelper - Test whether the condition described by 344 /// Pred, LHS, and RHS is true whenever the condition desribed by Pred, 345 /// FoundLHS, and FoundRHS is true. 346 bool isImpliedCondOperandsHelper(ICmpInst::Predicate Pred, 347 const SCEV *LHS, const SCEV *RHS, 348 const SCEV *FoundLHS, const SCEV *FoundRHS); 349 350 /// getConstantEvolutionLoopExitValue - If we know that the specified Phi is 351 /// in the header of its containing loop, we know the loop executes a 352 /// constant number of times, and the PHI node is just a recurrence 353 /// involving constants, fold it. 354 Constant *getConstantEvolutionLoopExitValue(PHINode *PN, const APInt& BEs, 355 const Loop *L); 356 357 public: 358 static char ID; // Pass identification, replacement for typeid 359 ScalarEvolution(); 360 361 LLVMContext &getContext() const { return F->getContext(); } 362 363 /// isSCEVable - Test if values of the given type are analyzable within 364 /// the SCEV framework. This primarily includes integer types, and it 365 /// can optionally include pointer types if the ScalarEvolution class 366 /// has access to target-specific information. 367 bool isSCEVable(const Type *Ty) const; 368 369 /// getTypeSizeInBits - Return the size in bits of the specified type, 370 /// for which isSCEVable must return true. 371 uint64_t getTypeSizeInBits(const Type *Ty) const; 372 373 /// getEffectiveSCEVType - Return a type with the same bitwidth as 374 /// the given type and which represents how SCEV will treat the given 375 /// type, for which isSCEVable must return true. For pointer types, 376 /// this is the pointer-sized integer type. 377 const Type *getEffectiveSCEVType(const Type *Ty) const; 378 379 /// getSCEV - Return a SCEV expression handle for the full generality of the 380 /// specified expression. 381 const SCEV *getSCEV(Value *V); 382 383 const SCEV *getConstant(ConstantInt *V); 384 const SCEV *getConstant(const APInt& Val); 385 const SCEV *getConstant(const Type *Ty, uint64_t V, bool isSigned = false); 386 const SCEV *getTruncateExpr(const SCEV *Op, const Type *Ty); 387 const SCEV *getZeroExtendExpr(const SCEV *Op, const Type *Ty); 388 const SCEV *getSignExtendExpr(const SCEV *Op, const Type *Ty); 389 const SCEV *getAnyExtendExpr(const SCEV *Op, const Type *Ty); 390 const SCEV *getAddExpr(SmallVectorImpl<const SCEV *> &Ops); 391 const SCEV *getAddExpr(const SCEV *LHS, const SCEV *RHS) { 392 SmallVector<const SCEV *, 2> Ops; 393 Ops.push_back(LHS); 394 Ops.push_back(RHS); 395 return getAddExpr(Ops); 396 } 397 const SCEV *getAddExpr(const SCEV *Op0, const SCEV *Op1, 398 const SCEV *Op2) { 399 SmallVector<const SCEV *, 3> Ops; 400 Ops.push_back(Op0); 401 Ops.push_back(Op1); 402 Ops.push_back(Op2); 403 return getAddExpr(Ops); 404 } 405 const SCEV *getMulExpr(SmallVectorImpl<const SCEV *> &Ops); 406 const SCEV *getMulExpr(const SCEV *LHS, const SCEV *RHS) { 407 SmallVector<const SCEV *, 2> Ops; 408 Ops.push_back(LHS); 409 Ops.push_back(RHS); 410 return getMulExpr(Ops); 411 } 412 const SCEV *getUDivExpr(const SCEV *LHS, const SCEV *RHS); 413 const SCEV *getAddRecExpr(const SCEV *Start, const SCEV *Step, 414 const Loop *L); 415 const SCEV *getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands, 416 const Loop *L); 417 const SCEV *getAddRecExpr(const SmallVectorImpl<const SCEV *> &Operands, 418 const Loop *L) { 419 SmallVector<const SCEV *, 4> NewOp(Operands.begin(), Operands.end()); 420 return getAddRecExpr(NewOp, L); 421 } 422 const SCEV *getSMaxExpr(const SCEV *LHS, const SCEV *RHS); 423 const SCEV *getSMaxExpr(SmallVectorImpl<const SCEV *> &Operands); 424 const SCEV *getUMaxExpr(const SCEV *LHS, const SCEV *RHS); 425 const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands); 426 const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS); 427 const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS); 428 const SCEV *getFieldOffsetExpr(const StructType *STy, unsigned FieldNo); 429 const SCEV *getAllocSizeExpr(const Type *AllocTy); 430 const SCEV *getUnknown(Value *V); 431 const SCEV *getCouldNotCompute(); 432 433 /// getNegativeSCEV - Return the SCEV object corresponding to -V. 434 /// 435 const SCEV *getNegativeSCEV(const SCEV *V); 436 437 /// getNotSCEV - Return the SCEV object corresponding to ~V. 438 /// 439 const SCEV *getNotSCEV(const SCEV *V); 440 441 /// getMinusSCEV - Return LHS-RHS. 442 /// 443 const SCEV *getMinusSCEV(const SCEV *LHS, 444 const SCEV *RHS); 445 446 /// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion 447 /// of the input value to the specified type. If the type must be 448 /// extended, it is zero extended. 449 const SCEV *getTruncateOrZeroExtend(const SCEV *V, const Type *Ty); 450 451 /// getTruncateOrSignExtend - 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 sign extended. 454 const SCEV *getTruncateOrSignExtend(const SCEV *V, const Type *Ty); 455 456 /// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of 457 /// the input value to the specified type. If the type must be extended, 458 /// it is zero extended. The conversion must not be narrowing. 459 const SCEV *getNoopOrZeroExtend(const SCEV *V, const Type *Ty); 460 461 /// getNoopOrSignExtend - 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 sign extended. The conversion must not be narrowing. 464 const SCEV *getNoopOrSignExtend(const SCEV *V, const Type *Ty); 465 466 /// getNoopOrAnyExtend - 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 extended with unspecified bits. The conversion must not be 469 /// narrowing. 470 const SCEV *getNoopOrAnyExtend(const SCEV *V, const Type *Ty); 471 472 /// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the 473 /// input value to the specified type. The conversion must not be 474 /// widening. 475 const SCEV *getTruncateOrNoop(const SCEV *V, const Type *Ty); 476 477 /// getIntegerSCEV - Given a SCEVable type, create a constant for the 478 /// specified signed integer value and return a SCEV for the constant. 479 const SCEV *getIntegerSCEV(int Val, const Type *Ty); 480 481 /// getUMaxFromMismatchedTypes - Promote the operands to the wider of 482 /// the types using zero-extension, and then perform a umax operation 483 /// with them. 484 const SCEV *getUMaxFromMismatchedTypes(const SCEV *LHS, 485 const SCEV *RHS); 486 487 /// getUMinFromMismatchedTypes - Promote the operands to the wider of 488 /// the types using zero-extension, and then perform a umin operation 489 /// with them. 490 const SCEV *getUMinFromMismatchedTypes(const SCEV *LHS, 491 const SCEV *RHS); 492 493 /// getSCEVAtScope - Return a SCEV expression handle for the specified value 494 /// at the specified scope in the program. The L value specifies a loop 495 /// nest to evaluate the expression at, where null is the top-level or a 496 /// specified loop is immediately inside of the loop. 497 /// 498 /// This method can be used to compute the exit value for a variable defined 499 /// in a loop by querying what the value will hold in the parent loop. 500 /// 501 /// In the case that a relevant loop exit value cannot be computed, the 502 /// original value V is returned. 503 const SCEV *getSCEVAtScope(const SCEV *S, const Loop *L); 504 505 /// getSCEVAtScope - This is a convenience function which does 506 /// getSCEVAtScope(getSCEV(V), L). 507 const SCEV *getSCEVAtScope(Value *V, const Loop *L); 508 509 /// isLoopGuardedByCond - Test whether entry to the loop is protected by 510 /// a conditional between LHS and RHS. This is used to help avoid max 511 /// expressions in loop trip counts, and to eliminate casts. 512 bool isLoopGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, 513 const SCEV *LHS, const SCEV *RHS); 514 515 /// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is 516 /// protected by a conditional between LHS and RHS. This is used to 517 /// to eliminate casts. 518 bool isLoopBackedgeGuardedByCond(const Loop *L, ICmpInst::Predicate Pred, 519 const SCEV *LHS, const SCEV *RHS); 520 521 /// getBackedgeTakenCount - If the specified loop has a predictable 522 /// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute 523 /// object. The backedge-taken count is the number of times the loop header 524 /// will be branched to from within the loop. This is one less than the 525 /// trip count of the loop, since it doesn't count the first iteration, 526 /// when the header is branched to from outside the loop. 527 /// 528 /// Note that it is not valid to call this method on a loop without a 529 /// loop-invariant backedge-taken count (see 530 /// hasLoopInvariantBackedgeTakenCount). 531 /// 532 const SCEV *getBackedgeTakenCount(const Loop *L); 533 534 /// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except 535 /// return the least SCEV value that is known never to be less than the 536 /// actual backedge taken count. 537 const SCEV *getMaxBackedgeTakenCount(const Loop *L); 538 539 /// hasLoopInvariantBackedgeTakenCount - Return true if the specified loop 540 /// has an analyzable loop-invariant backedge-taken count. 541 bool hasLoopInvariantBackedgeTakenCount(const Loop *L); 542 543 /// forgetLoopBackedgeTakenCount - This method should be called by the 544 /// client when it has changed a loop in a way that may effect 545 /// ScalarEvolution's ability to compute a trip count, or if the loop 546 /// is deleted. 547 void forgetLoopBackedgeTakenCount(const Loop *L); 548 549 /// GetMinTrailingZeros - Determine the minimum number of zero bits that S 550 /// is guaranteed to end in (at every loop iteration). It is, at the same 551 /// time, the minimum number of times S is divisible by 2. For example, 552 /// given {4,+,8} it returns 2. If S is guaranteed to be 0, it returns the 553 /// bitwidth of S. 554 uint32_t GetMinTrailingZeros(const SCEV *S); 555 556 /// getUnsignedRange - Determine the unsigned range for a particular SCEV. 557 /// 558 ConstantRange getUnsignedRange(const SCEV *S); 559 560 /// getSignedRange - Determine the signed range for a particular SCEV. 561 /// 562 ConstantRange getSignedRange(const SCEV *S); 563 564 /// isKnownNegative - Test if the given expression is known to be negative. 565 /// 566 bool isKnownNegative(const SCEV *S); 567 568 /// isKnownPositive - Test if the given expression is known to be positive. 569 /// 570 bool isKnownPositive(const SCEV *S); 571 572 /// isKnownNonNegative - Test if the given expression is known to be 573 /// non-negative. 574 /// 575 bool isKnownNonNegative(const SCEV *S); 576 577 /// isKnownNonPositive - Test if the given expression is known to be 578 /// non-positive. 579 /// 580 bool isKnownNonPositive(const SCEV *S); 581 582 /// isKnownNonZero - Test if the given expression is known to be 583 /// non-zero. 584 /// 585 bool isKnownNonZero(const SCEV *S); 586 587 /// isKnownNonZero - Test if the given expression is known to satisfy 588 /// the condition described by Pred, LHS, and RHS. 589 /// 590 bool isKnownPredicate(ICmpInst::Predicate Pred, 591 const SCEV *LHS, const SCEV *RHS); 592 593 virtual bool runOnFunction(Function &F); 594 virtual void releaseMemory(); 595 virtual void getAnalysisUsage(AnalysisUsage &AU) const; 596 virtual void print(raw_ostream &OS, const Module* = 0) const; 597 598 private: 599 FoldingSet<SCEV> UniqueSCEVs; 600 BumpPtrAllocator SCEVAllocator; 601 }; 602} 603 604#endif 605