ScalarEvolutionExpressions.h revision 203a7239ae928568fe7a34c03ead4b1b3133870e
1//===- llvm/Analysis/ScalarEvolutionExpressions.h - SCEV Exprs --*- 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// This file defines the classes used to represent and build scalar expressions. 11// 12//===----------------------------------------------------------------------===// 13 14#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H 15#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H 16 17#include "llvm/Analysis/ScalarEvolution.h" 18#include "llvm/Support/ErrorHandling.h" 19 20namespace llvm { 21 class ConstantInt; 22 class ConstantRange; 23 class DominatorTree; 24 25 enum SCEVTypes { 26 // These should be ordered in terms of increasing complexity to make the 27 // folders simpler. 28 scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr, 29 scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr, 30 scUnknown, scCouldNotCompute 31 }; 32 33 //===--------------------------------------------------------------------===// 34 /// SCEVConstant - This class represents a constant integer value. 35 /// 36 class SCEVConstant : public SCEV { 37 friend class ScalarEvolution; 38 39 ConstantInt *V; 40 SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) : 41 SCEV(ID, scConstant), V(v) {} 42 public: 43 ConstantInt *getValue() const { return V; } 44 45 virtual bool isLoopInvariant(const Loop *L) const { 46 return true; 47 } 48 49 virtual bool hasComputableLoopEvolution(const Loop *L) const { 50 return false; // Not loop variant 51 } 52 53 virtual const Type *getType() const; 54 55 virtual bool hasOperand(const SCEV *) const { 56 return false; 57 } 58 59 bool dominates(BasicBlock *BB, DominatorTree *DT) const { 60 return true; 61 } 62 63 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const { 64 return true; 65 } 66 67 virtual void print(raw_ostream &OS) const; 68 69 /// Methods for support type inquiry through isa, cast, and dyn_cast: 70 static inline bool classof(const SCEVConstant *S) { return true; } 71 static inline bool classof(const SCEV *S) { 72 return S->getSCEVType() == scConstant; 73 } 74 }; 75 76 //===--------------------------------------------------------------------===// 77 /// SCEVCastExpr - This is the base class for unary cast operator classes. 78 /// 79 class SCEVCastExpr : public SCEV { 80 protected: 81 const SCEV *Op; 82 const Type *Ty; 83 84 SCEVCastExpr(const FoldingSetNodeIDRef ID, 85 unsigned SCEVTy, const SCEV *op, const Type *ty); 86 87 public: 88 const SCEV *getOperand() const { return Op; } 89 virtual const Type *getType() const { return Ty; } 90 91 virtual bool isLoopInvariant(const Loop *L) const { 92 return Op->isLoopInvariant(L); 93 } 94 95 virtual bool hasComputableLoopEvolution(const Loop *L) const { 96 return Op->hasComputableLoopEvolution(L); 97 } 98 99 virtual bool hasOperand(const SCEV *O) const { 100 return Op == O || Op->hasOperand(O); 101 } 102 103 virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const; 104 105 virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 106 107 /// Methods for support type inquiry through isa, cast, and dyn_cast: 108 static inline bool classof(const SCEVCastExpr *S) { return true; } 109 static inline bool classof(const SCEV *S) { 110 return S->getSCEVType() == scTruncate || 111 S->getSCEVType() == scZeroExtend || 112 S->getSCEVType() == scSignExtend; 113 } 114 }; 115 116 //===--------------------------------------------------------------------===// 117 /// SCEVTruncateExpr - This class represents a truncation of an integer value 118 /// to a smaller integer value. 119 /// 120 class SCEVTruncateExpr : public SCEVCastExpr { 121 friend class ScalarEvolution; 122 123 SCEVTruncateExpr(const FoldingSetNodeIDRef ID, 124 const SCEV *op, const Type *ty); 125 126 public: 127 virtual void print(raw_ostream &OS) const; 128 129 /// Methods for support type inquiry through isa, cast, and dyn_cast: 130 static inline bool classof(const SCEVTruncateExpr *S) { return true; } 131 static inline bool classof(const SCEV *S) { 132 return S->getSCEVType() == scTruncate; 133 } 134 }; 135 136 //===--------------------------------------------------------------------===// 137 /// SCEVZeroExtendExpr - This class represents a zero extension of a small 138 /// integer value to a larger integer value. 139 /// 140 class SCEVZeroExtendExpr : public SCEVCastExpr { 141 friend class ScalarEvolution; 142 143 SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID, 144 const SCEV *op, const Type *ty); 145 146 public: 147 virtual void print(raw_ostream &OS) const; 148 149 /// Methods for support type inquiry through isa, cast, and dyn_cast: 150 static inline bool classof(const SCEVZeroExtendExpr *S) { return true; } 151 static inline bool classof(const SCEV *S) { 152 return S->getSCEVType() == scZeroExtend; 153 } 154 }; 155 156 //===--------------------------------------------------------------------===// 157 /// SCEVSignExtendExpr - This class represents a sign extension of a small 158 /// integer value to a larger integer value. 159 /// 160 class SCEVSignExtendExpr : public SCEVCastExpr { 161 friend class ScalarEvolution; 162 163 SCEVSignExtendExpr(const FoldingSetNodeIDRef ID, 164 const SCEV *op, const Type *ty); 165 166 public: 167 virtual void print(raw_ostream &OS) const; 168 169 /// Methods for support type inquiry through isa, cast, and dyn_cast: 170 static inline bool classof(const SCEVSignExtendExpr *S) { return true; } 171 static inline bool classof(const SCEV *S) { 172 return S->getSCEVType() == scSignExtend; 173 } 174 }; 175 176 177 //===--------------------------------------------------------------------===// 178 /// SCEVNAryExpr - This node is a base class providing common 179 /// functionality for n'ary operators. 180 /// 181 class SCEVNAryExpr : public SCEV { 182 protected: 183 // Since SCEVs are immutable, ScalarEvolution allocates operand 184 // arrays with its SCEVAllocator, so this class just needs a simple 185 // pointer rather than a more elaborate vector-like data structure. 186 // This also avoids the need for a non-trivial destructor. 187 const SCEV *const *Operands; 188 size_t NumOperands; 189 190 SCEVNAryExpr(const FoldingSetNodeIDRef ID, 191 enum SCEVTypes T, const SCEV *const *O, size_t N) 192 : SCEV(ID, T), Operands(O), NumOperands(N) {} 193 194 public: 195 size_t getNumOperands() const { return NumOperands; } 196 const SCEV *getOperand(unsigned i) const { 197 assert(i < NumOperands && "Operand index out of range!"); 198 return Operands[i]; 199 } 200 201 typedef const SCEV *const *op_iterator; 202 op_iterator op_begin() const { return Operands; } 203 op_iterator op_end() const { return Operands + NumOperands; } 204 205 virtual bool isLoopInvariant(const Loop *L) const; 206 207 // hasComputableLoopEvolution - N-ary expressions have computable loop 208 // evolutions iff they have at least one operand that varies with the loop, 209 // but that all varying operands are computable. 210 virtual bool hasComputableLoopEvolution(const Loop *L) const; 211 212 virtual bool hasOperand(const SCEV *O) const; 213 214 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 215 216 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 217 218 virtual const Type *getType() const { return getOperand(0)->getType(); } 219 220 bool hasNoUnsignedWrap() const { return SubclassData & (1 << 0); } 221 void setHasNoUnsignedWrap(bool B) { 222 SubclassData = (SubclassData & ~(1 << 0)) | (B << 0); 223 } 224 bool hasNoSignedWrap() const { return SubclassData & (1 << 1); } 225 void setHasNoSignedWrap(bool B) { 226 SubclassData = (SubclassData & ~(1 << 1)) | (B << 1); 227 } 228 229 /// Methods for support type inquiry through isa, cast, and dyn_cast: 230 static inline bool classof(const SCEVNAryExpr *S) { return true; } 231 static inline bool classof(const SCEV *S) { 232 return S->getSCEVType() == scAddExpr || 233 S->getSCEVType() == scMulExpr || 234 S->getSCEVType() == scSMaxExpr || 235 S->getSCEVType() == scUMaxExpr || 236 S->getSCEVType() == scAddRecExpr; 237 } 238 }; 239 240 //===--------------------------------------------------------------------===// 241 /// SCEVCommutativeExpr - This node is the base class for n'ary commutative 242 /// operators. 243 /// 244 class SCEVCommutativeExpr : public SCEVNAryExpr { 245 protected: 246 SCEVCommutativeExpr(const FoldingSetNodeIDRef ID, 247 enum SCEVTypes T, const SCEV *const *O, size_t N) 248 : SCEVNAryExpr(ID, T, O, N) {} 249 250 public: 251 virtual const char *getOperationStr() const = 0; 252 253 virtual void print(raw_ostream &OS) const; 254 255 /// Methods for support type inquiry through isa, cast, and dyn_cast: 256 static inline bool classof(const SCEVCommutativeExpr *S) { return true; } 257 static inline bool classof(const SCEV *S) { 258 return S->getSCEVType() == scAddExpr || 259 S->getSCEVType() == scMulExpr || 260 S->getSCEVType() == scSMaxExpr || 261 S->getSCEVType() == scUMaxExpr; 262 } 263 }; 264 265 266 //===--------------------------------------------------------------------===// 267 /// SCEVAddExpr - This node represents an addition of some number of SCEVs. 268 /// 269 class SCEVAddExpr : public SCEVCommutativeExpr { 270 friend class ScalarEvolution; 271 272 SCEVAddExpr(const FoldingSetNodeIDRef ID, 273 const SCEV *const *O, size_t N) 274 : SCEVCommutativeExpr(ID, scAddExpr, O, N) { 275 } 276 277 public: 278 virtual const char *getOperationStr() const { return " + "; } 279 280 virtual const Type *getType() const { 281 // Use the type of the last operand, which is likely to be a pointer 282 // type, if there is one. This doesn't usually matter, but it can help 283 // reduce casts when the expressions are expanded. 284 return getOperand(getNumOperands() - 1)->getType(); 285 } 286 287 /// Methods for support type inquiry through isa, cast, and dyn_cast: 288 static inline bool classof(const SCEVAddExpr *S) { return true; } 289 static inline bool classof(const SCEV *S) { 290 return S->getSCEVType() == scAddExpr; 291 } 292 }; 293 294 //===--------------------------------------------------------------------===// 295 /// SCEVMulExpr - This node represents multiplication of some number of SCEVs. 296 /// 297 class SCEVMulExpr : public SCEVCommutativeExpr { 298 friend class ScalarEvolution; 299 300 SCEVMulExpr(const FoldingSetNodeIDRef ID, 301 const SCEV *const *O, size_t N) 302 : SCEVCommutativeExpr(ID, scMulExpr, O, N) { 303 } 304 305 public: 306 virtual const char *getOperationStr() const { return " * "; } 307 308 /// Methods for support type inquiry through isa, cast, and dyn_cast: 309 static inline bool classof(const SCEVMulExpr *S) { return true; } 310 static inline bool classof(const SCEV *S) { 311 return S->getSCEVType() == scMulExpr; 312 } 313 }; 314 315 316 //===--------------------------------------------------------------------===// 317 /// SCEVUDivExpr - This class represents a binary unsigned division operation. 318 /// 319 class SCEVUDivExpr : public SCEV { 320 friend class ScalarEvolution; 321 322 const SCEV *LHS; 323 const SCEV *RHS; 324 SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs) 325 : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {} 326 327 public: 328 const SCEV *getLHS() const { return LHS; } 329 const SCEV *getRHS() const { return RHS; } 330 331 virtual bool isLoopInvariant(const Loop *L) const { 332 return LHS->isLoopInvariant(L) && RHS->isLoopInvariant(L); 333 } 334 335 virtual bool hasComputableLoopEvolution(const Loop *L) const { 336 return LHS->hasComputableLoopEvolution(L) && 337 RHS->hasComputableLoopEvolution(L); 338 } 339 340 virtual bool hasOperand(const SCEV *O) const { 341 return O == LHS || O == RHS || LHS->hasOperand(O) || RHS->hasOperand(O); 342 } 343 344 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 345 346 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 347 348 virtual const Type *getType() const; 349 350 void print(raw_ostream &OS) const; 351 352 /// Methods for support type inquiry through isa, cast, and dyn_cast: 353 static inline bool classof(const SCEVUDivExpr *S) { return true; } 354 static inline bool classof(const SCEV *S) { 355 return S->getSCEVType() == scUDivExpr; 356 } 357 }; 358 359 360 //===--------------------------------------------------------------------===// 361 /// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip 362 /// count of the specified loop. This is the primary focus of the 363 /// ScalarEvolution framework; all the other SCEV subclasses are mostly just 364 /// supporting infrastructure to allow SCEVAddRecExpr expressions to be 365 /// created and analyzed. 366 /// 367 /// All operands of an AddRec are required to be loop invariant. 368 /// 369 class SCEVAddRecExpr : public SCEVNAryExpr { 370 friend class ScalarEvolution; 371 372 const Loop *L; 373 374 SCEVAddRecExpr(const FoldingSetNodeIDRef ID, 375 const SCEV *const *O, size_t N, const Loop *l) 376 : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {} 377 378 public: 379 const SCEV *getStart() const { return Operands[0]; } 380 const Loop *getLoop() const { return L; } 381 382 /// getStepRecurrence - This method constructs and returns the recurrence 383 /// indicating how much this expression steps by. If this is a polynomial 384 /// of degree N, it returns a chrec of degree N-1. 385 const SCEV *getStepRecurrence(ScalarEvolution &SE) const { 386 if (isAffine()) return getOperand(1); 387 return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1, 388 op_end()), 389 getLoop()); 390 } 391 392 virtual bool hasComputableLoopEvolution(const Loop *QL) const { 393 return L == QL; 394 } 395 396 virtual bool isLoopInvariant(const Loop *QueryLoop) const; 397 398 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 399 400 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 401 402 /// isAffine - Return true if this is an affine AddRec (i.e., it represents 403 /// an expressions A+B*x where A and B are loop invariant values. 404 bool isAffine() const { 405 // We know that the start value is invariant. This expression is thus 406 // affine iff the step is also invariant. 407 return getNumOperands() == 2; 408 } 409 410 /// isQuadratic - Return true if this is an quadratic AddRec (i.e., it 411 /// represents an expressions A+B*x+C*x^2 where A, B and C are loop 412 /// invariant values. This corresponds to an addrec of the form {L,+,M,+,N} 413 bool isQuadratic() const { 414 return getNumOperands() == 3; 415 } 416 417 /// evaluateAtIteration - Return the value of this chain of recurrences at 418 /// the specified iteration number. 419 const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const; 420 421 /// getNumIterationsInRange - Return the number of iterations of this loop 422 /// that produce values in the specified constant range. Another way of 423 /// looking at this is that it returns the first iteration number where the 424 /// value is not in the condition, thus computing the exit count. If the 425 /// iteration count can't be computed, an instance of SCEVCouldNotCompute is 426 /// returned. 427 const SCEV *getNumIterationsInRange(ConstantRange Range, 428 ScalarEvolution &SE) const; 429 430 /// getPostIncExpr - Return an expression representing the value of 431 /// this expression one iteration of the loop ahead. 432 const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const { 433 return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE))); 434 } 435 436 virtual void print(raw_ostream &OS) const; 437 438 /// Methods for support type inquiry through isa, cast, and dyn_cast: 439 static inline bool classof(const SCEVAddRecExpr *S) { return true; } 440 static inline bool classof(const SCEV *S) { 441 return S->getSCEVType() == scAddRecExpr; 442 } 443 }; 444 445 446 //===--------------------------------------------------------------------===// 447 /// SCEVSMaxExpr - This class represents a signed maximum selection. 448 /// 449 class SCEVSMaxExpr : public SCEVCommutativeExpr { 450 friend class ScalarEvolution; 451 452 SCEVSMaxExpr(const FoldingSetNodeIDRef ID, 453 const SCEV *const *O, size_t N) 454 : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) { 455 // Max never overflows. 456 setHasNoUnsignedWrap(true); 457 setHasNoSignedWrap(true); 458 } 459 460 public: 461 virtual const char *getOperationStr() const { return " smax "; } 462 463 /// Methods for support type inquiry through isa, cast, and dyn_cast: 464 static inline bool classof(const SCEVSMaxExpr *S) { return true; } 465 static inline bool classof(const SCEV *S) { 466 return S->getSCEVType() == scSMaxExpr; 467 } 468 }; 469 470 471 //===--------------------------------------------------------------------===// 472 /// SCEVUMaxExpr - This class represents an unsigned maximum selection. 473 /// 474 class SCEVUMaxExpr : public SCEVCommutativeExpr { 475 friend class ScalarEvolution; 476 477 SCEVUMaxExpr(const FoldingSetNodeIDRef ID, 478 const SCEV *const *O, size_t N) 479 : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) { 480 // Max never overflows. 481 setHasNoUnsignedWrap(true); 482 setHasNoSignedWrap(true); 483 } 484 485 public: 486 virtual const char *getOperationStr() const { return " umax "; } 487 488 /// Methods for support type inquiry through isa, cast, and dyn_cast: 489 static inline bool classof(const SCEVUMaxExpr *S) { return true; } 490 static inline bool classof(const SCEV *S) { 491 return S->getSCEVType() == scUMaxExpr; 492 } 493 }; 494 495 //===--------------------------------------------------------------------===// 496 /// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV 497 /// value, and only represent it as its LLVM Value. This is the "bottom" 498 /// value for the analysis. 499 /// 500 class SCEVUnknown : public SCEV, private CallbackVH { 501 friend class ScalarEvolution; 502 503 // Implement CallbackVH. 504 virtual void deleted(); 505 virtual void allUsesReplacedWith(Value *New); 506 507 /// SE - The parent ScalarEvolution value. This is used to update 508 /// the parent's maps when the value associated with a SCEVUnknown 509 /// is deleted or RAUW'd. 510 ScalarEvolution *SE; 511 512 /// Next - The next pointer in the linked list of all 513 /// SCEVUnknown instances owned by a ScalarEvolution. 514 SCEVUnknown *Next; 515 516 SCEVUnknown(const FoldingSetNodeIDRef ID, Value *V, 517 ScalarEvolution *se, SCEVUnknown *next) : 518 SCEV(ID, scUnknown), CallbackVH(V), SE(se), Next(next) {} 519 520 public: 521 Value *getValue() const { return getValPtr(); } 522 523 /// isSizeOf, isAlignOf, isOffsetOf - Test whether this is a special 524 /// constant representing a type size, alignment, or field offset in 525 /// a target-independent manner, and hasn't happened to have been 526 /// folded with other operations into something unrecognizable. This 527 /// is mainly only useful for pretty-printing and other situations 528 /// where it isn't absolutely required for these to succeed. 529 bool isSizeOf(const Type *&AllocTy) const; 530 bool isAlignOf(const Type *&AllocTy) const; 531 bool isOffsetOf(const Type *&STy, Constant *&FieldNo) const; 532 533 virtual bool isLoopInvariant(const Loop *L) const; 534 virtual bool hasComputableLoopEvolution(const Loop *QL) const { 535 return false; // not computable 536 } 537 538 virtual bool hasOperand(const SCEV *) const { 539 return false; 540 } 541 542 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 543 544 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 545 546 virtual const Type *getType() const; 547 548 virtual void print(raw_ostream &OS) const; 549 550 /// Methods for support type inquiry through isa, cast, and dyn_cast: 551 static inline bool classof(const SCEVUnknown *S) { return true; } 552 static inline bool classof(const SCEV *S) { 553 return S->getSCEVType() == scUnknown; 554 } 555 }; 556 557 /// SCEVVisitor - This class defines a simple visitor class that may be used 558 /// for various SCEV analysis purposes. 559 template<typename SC, typename RetVal=void> 560 struct SCEVVisitor { 561 RetVal visit(const SCEV *S) { 562 switch (S->getSCEVType()) { 563 case scConstant: 564 return ((SC*)this)->visitConstant((const SCEVConstant*)S); 565 case scTruncate: 566 return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S); 567 case scZeroExtend: 568 return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S); 569 case scSignExtend: 570 return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S); 571 case scAddExpr: 572 return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S); 573 case scMulExpr: 574 return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S); 575 case scUDivExpr: 576 return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S); 577 case scAddRecExpr: 578 return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S); 579 case scSMaxExpr: 580 return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S); 581 case scUMaxExpr: 582 return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S); 583 case scUnknown: 584 return ((SC*)this)->visitUnknown((const SCEVUnknown*)S); 585 case scCouldNotCompute: 586 return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S); 587 default: 588 llvm_unreachable("Unknown SCEV type!"); 589 } 590 } 591 592 RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) { 593 llvm_unreachable("Invalid use of SCEVCouldNotCompute!"); 594 return RetVal(); 595 } 596 }; 597} 598 599#endif 600