ScalarEvolutionExpressions.h revision ebf78f18df84a63295c748148f54f091234ed099
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 FoldingSetNodeID &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 FoldingSetNodeID &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 FoldingSetNodeID &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 FoldingSetNodeID &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 FoldingSetNodeID &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 SmallVector<const SCEV *, 8> Operands; 184 185 SCEVNAryExpr(const FoldingSetNodeID &ID, 186 enum SCEVTypes T, const SmallVectorImpl<const SCEV *> &ops) 187 : SCEV(ID, T), Operands(ops.begin(), ops.end()) {} 188 189 public: 190 unsigned getNumOperands() const { return (unsigned)Operands.size(); } 191 const SCEV *getOperand(unsigned i) const { 192 assert(i < Operands.size() && "Operand index out of range!"); 193 return Operands[i]; 194 } 195 196 const SmallVectorImpl<const SCEV *> &getOperands() const { 197 return Operands; 198 } 199 typedef SmallVectorImpl<const SCEV *>::const_iterator op_iterator; 200 op_iterator op_begin() const { return Operands.begin(); } 201 op_iterator op_end() const { return Operands.end(); } 202 203 virtual bool isLoopInvariant(const Loop *L) const { 204 for (unsigned i = 0, e = getNumOperands(); i != e; ++i) 205 if (!getOperand(i)->isLoopInvariant(L)) return false; 206 return true; 207 } 208 209 // hasComputableLoopEvolution - N-ary expressions have computable loop 210 // evolutions iff they have at least one operand that varies with the loop, 211 // but that all varying operands are computable. 212 virtual bool hasComputableLoopEvolution(const Loop *L) const { 213 bool HasVarying = false; 214 for (unsigned i = 0, e = getNumOperands(); i != e; ++i) 215 if (!getOperand(i)->isLoopInvariant(L)) { 216 if (getOperand(i)->hasComputableLoopEvolution(L)) 217 HasVarying = true; 218 else 219 return false; 220 } 221 return HasVarying; 222 } 223 224 virtual bool hasOperand(const SCEV *O) const { 225 for (unsigned i = 0, e = getNumOperands(); i != e; ++i) 226 if (O == getOperand(i) || getOperand(i)->hasOperand(O)) 227 return true; 228 return false; 229 } 230 231 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 232 233 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 234 235 virtual const Type *getType() const { return getOperand(0)->getType(); } 236 237 bool hasNoUnsignedWrap() const { return SubclassData & (1 << 0); } 238 void setHasNoUnsignedWrap(bool B) { 239 SubclassData = (SubclassData & ~(1 << 0)) | (B << 0); 240 } 241 bool hasNoSignedWrap() const { return SubclassData & (1 << 1); } 242 void setHasNoSignedWrap(bool B) { 243 SubclassData = (SubclassData & ~(1 << 1)) | (B << 1); 244 } 245 246 /// Methods for support type inquiry through isa, cast, and dyn_cast: 247 static inline bool classof(const SCEVNAryExpr *S) { return true; } 248 static inline bool classof(const SCEV *S) { 249 return S->getSCEVType() == scAddExpr || 250 S->getSCEVType() == scMulExpr || 251 S->getSCEVType() == scSMaxExpr || 252 S->getSCEVType() == scUMaxExpr || 253 S->getSCEVType() == scAddRecExpr; 254 } 255 }; 256 257 //===--------------------------------------------------------------------===// 258 /// SCEVCommutativeExpr - This node is the base class for n'ary commutative 259 /// operators. 260 /// 261 class SCEVCommutativeExpr : public SCEVNAryExpr { 262 protected: 263 SCEVCommutativeExpr(const FoldingSetNodeID &ID, 264 enum SCEVTypes T, 265 const SmallVectorImpl<const SCEV *> &ops) 266 : SCEVNAryExpr(ID, T, ops) {} 267 268 public: 269 virtual const char *getOperationStr() const = 0; 270 271 virtual void print(raw_ostream &OS) const; 272 273 /// Methods for support type inquiry through isa, cast, and dyn_cast: 274 static inline bool classof(const SCEVCommutativeExpr *S) { return true; } 275 static inline bool classof(const SCEV *S) { 276 return S->getSCEVType() == scAddExpr || 277 S->getSCEVType() == scMulExpr || 278 S->getSCEVType() == scSMaxExpr || 279 S->getSCEVType() == scUMaxExpr; 280 } 281 }; 282 283 284 //===--------------------------------------------------------------------===// 285 /// SCEVAddExpr - This node represents an addition of some number of SCEVs. 286 /// 287 class SCEVAddExpr : public SCEVCommutativeExpr { 288 friend class ScalarEvolution; 289 290 SCEVAddExpr(const FoldingSetNodeID &ID, 291 const SmallVectorImpl<const SCEV *> &ops) 292 : SCEVCommutativeExpr(ID, scAddExpr, ops) { 293 } 294 295 public: 296 virtual const char *getOperationStr() const { return " + "; } 297 298 virtual const Type *getType() const { 299 // Use the type of the last operand, which is likely to be a pointer 300 // type, if there is one. This doesn't usually matter, but it can help 301 // reduce casts when the expressions are expanded. 302 return getOperand(getNumOperands() - 1)->getType(); 303 } 304 305 /// Methods for support type inquiry through isa, cast, and dyn_cast: 306 static inline bool classof(const SCEVAddExpr *S) { return true; } 307 static inline bool classof(const SCEV *S) { 308 return S->getSCEVType() == scAddExpr; 309 } 310 }; 311 312 //===--------------------------------------------------------------------===// 313 /// SCEVMulExpr - This node represents multiplication of some number of SCEVs. 314 /// 315 class SCEVMulExpr : public SCEVCommutativeExpr { 316 friend class ScalarEvolution; 317 318 SCEVMulExpr(const FoldingSetNodeID &ID, 319 const SmallVectorImpl<const SCEV *> &ops) 320 : SCEVCommutativeExpr(ID, scMulExpr, ops) { 321 } 322 323 public: 324 virtual const char *getOperationStr() const { return " * "; } 325 326 /// Methods for support type inquiry through isa, cast, and dyn_cast: 327 static inline bool classof(const SCEVMulExpr *S) { return true; } 328 static inline bool classof(const SCEV *S) { 329 return S->getSCEVType() == scMulExpr; 330 } 331 }; 332 333 334 //===--------------------------------------------------------------------===// 335 /// SCEVUDivExpr - This class represents a binary unsigned division operation. 336 /// 337 class SCEVUDivExpr : public SCEV { 338 friend class ScalarEvolution; 339 340 const SCEV *LHS; 341 const SCEV *RHS; 342 SCEVUDivExpr(const FoldingSetNodeID &ID, const SCEV *lhs, const SCEV *rhs) 343 : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {} 344 345 public: 346 const SCEV *getLHS() const { return LHS; } 347 const SCEV *getRHS() const { return RHS; } 348 349 virtual bool isLoopInvariant(const Loop *L) const { 350 return LHS->isLoopInvariant(L) && RHS->isLoopInvariant(L); 351 } 352 353 virtual bool hasComputableLoopEvolution(const Loop *L) const { 354 return LHS->hasComputableLoopEvolution(L) && 355 RHS->hasComputableLoopEvolution(L); 356 } 357 358 virtual bool hasOperand(const SCEV *O) const { 359 return O == LHS || O == RHS || LHS->hasOperand(O) || RHS->hasOperand(O); 360 } 361 362 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 363 364 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 365 366 virtual const Type *getType() const; 367 368 void print(raw_ostream &OS) const; 369 370 /// Methods for support type inquiry through isa, cast, and dyn_cast: 371 static inline bool classof(const SCEVUDivExpr *S) { return true; } 372 static inline bool classof(const SCEV *S) { 373 return S->getSCEVType() == scUDivExpr; 374 } 375 }; 376 377 378 //===--------------------------------------------------------------------===// 379 /// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip 380 /// count of the specified loop. This is the primary focus of the 381 /// ScalarEvolution framework; all the other SCEV subclasses are mostly just 382 /// supporting infrastructure to allow SCEVAddRecExpr expressions to be 383 /// created and analyzed. 384 /// 385 /// All operands of an AddRec are required to be loop invariant. 386 /// 387 class SCEVAddRecExpr : public SCEVNAryExpr { 388 friend class ScalarEvolution; 389 390 const Loop *L; 391 392 SCEVAddRecExpr(const FoldingSetNodeID &ID, 393 const SmallVectorImpl<const SCEV *> &ops, const Loop *l) 394 : SCEVNAryExpr(ID, scAddRecExpr, ops), L(l) { 395 for (size_t i = 0, e = Operands.size(); i != e; ++i) 396 assert(Operands[i]->isLoopInvariant(l) && 397 "Operands of AddRec must be loop-invariant!"); 398 } 399 400 public: 401 const SCEV *getStart() const { return Operands[0]; } 402 const Loop *getLoop() const { return L; } 403 404 /// getStepRecurrence - This method constructs and returns the recurrence 405 /// indicating how much this expression steps by. If this is a polynomial 406 /// of degree N, it returns a chrec of degree N-1. 407 const SCEV *getStepRecurrence(ScalarEvolution &SE) const { 408 if (isAffine()) return getOperand(1); 409 return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1, 410 op_end()), 411 getLoop()); 412 } 413 414 virtual bool hasComputableLoopEvolution(const Loop *QL) const { 415 return L == QL; 416 } 417 418 virtual bool isLoopInvariant(const Loop *QueryLoop) const; 419 420 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 421 422 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 423 424 /// isAffine - Return true if this is an affine AddRec (i.e., it represents 425 /// an expressions A+B*x where A and B are loop invariant values. 426 bool isAffine() const { 427 // We know that the start value is invariant. This expression is thus 428 // affine iff the step is also invariant. 429 return getNumOperands() == 2; 430 } 431 432 /// isQuadratic - Return true if this is an quadratic AddRec (i.e., it 433 /// represents an expressions A+B*x+C*x^2 where A, B and C are loop 434 /// invariant values. This corresponds to an addrec of the form {L,+,M,+,N} 435 bool isQuadratic() const { 436 return getNumOperands() == 3; 437 } 438 439 /// evaluateAtIteration - Return the value of this chain of recurrences at 440 /// the specified iteration number. 441 const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const; 442 443 /// getNumIterationsInRange - Return the number of iterations of this loop 444 /// that produce values in the specified constant range. Another way of 445 /// looking at this is that it returns the first iteration number where the 446 /// value is not in the condition, thus computing the exit count. If the 447 /// iteration count can't be computed, an instance of SCEVCouldNotCompute is 448 /// returned. 449 const SCEV *getNumIterationsInRange(ConstantRange Range, 450 ScalarEvolution &SE) const; 451 452 /// getPostIncExpr - Return an expression representing the value of 453 /// this expression one iteration of the loop ahead. 454 const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const { 455 return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE))); 456 } 457 458 virtual void print(raw_ostream &OS) const; 459 460 /// Methods for support type inquiry through isa, cast, and dyn_cast: 461 static inline bool classof(const SCEVAddRecExpr *S) { return true; } 462 static inline bool classof(const SCEV *S) { 463 return S->getSCEVType() == scAddRecExpr; 464 } 465 }; 466 467 468 //===--------------------------------------------------------------------===// 469 /// SCEVSMaxExpr - This class represents a signed maximum selection. 470 /// 471 class SCEVSMaxExpr : public SCEVCommutativeExpr { 472 friend class ScalarEvolution; 473 474 SCEVSMaxExpr(const FoldingSetNodeID &ID, 475 const SmallVectorImpl<const SCEV *> &ops) 476 : SCEVCommutativeExpr(ID, scSMaxExpr, ops) { 477 // Max never overflows. 478 setHasNoUnsignedWrap(true); 479 setHasNoSignedWrap(true); 480 } 481 482 public: 483 virtual const char *getOperationStr() const { return " smax "; } 484 485 /// Methods for support type inquiry through isa, cast, and dyn_cast: 486 static inline bool classof(const SCEVSMaxExpr *S) { return true; } 487 static inline bool classof(const SCEV *S) { 488 return S->getSCEVType() == scSMaxExpr; 489 } 490 }; 491 492 493 //===--------------------------------------------------------------------===// 494 /// SCEVUMaxExpr - This class represents an unsigned maximum selection. 495 /// 496 class SCEVUMaxExpr : public SCEVCommutativeExpr { 497 friend class ScalarEvolution; 498 499 SCEVUMaxExpr(const FoldingSetNodeID &ID, 500 const SmallVectorImpl<const SCEV *> &ops) 501 : SCEVCommutativeExpr(ID, scUMaxExpr, ops) { 502 // Max never overflows. 503 setHasNoUnsignedWrap(true); 504 setHasNoSignedWrap(true); 505 } 506 507 public: 508 virtual const char *getOperationStr() const { return " umax "; } 509 510 /// Methods for support type inquiry through isa, cast, and dyn_cast: 511 static inline bool classof(const SCEVUMaxExpr *S) { return true; } 512 static inline bool classof(const SCEV *S) { 513 return S->getSCEVType() == scUMaxExpr; 514 } 515 }; 516 517 //===--------------------------------------------------------------------===// 518 /// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV 519 /// value, and only represent it as its LLVM Value. This is the "bottom" 520 /// value for the analysis. 521 /// 522 class SCEVUnknown : public SCEV { 523 friend class ScalarEvolution; 524 525 Value *V; 526 SCEVUnknown(const FoldingSetNodeID &ID, Value *v) : 527 SCEV(ID, scUnknown), V(v) {} 528 529 public: 530 Value *getValue() const { return V; } 531 532 /// isSizeOf, isAlignOf, isOffsetOf - Test whether this is a special 533 /// constant representing a type size, alignment, or field offset in 534 /// a target-independent manner, and hasn't happened to have been 535 /// folded with other operations into something unrecognizable. This 536 /// is mainly only useful for pretty-printing and other situations 537 /// where it isn't absolutely required for these to succeed. 538 bool isSizeOf(const Type *&AllocTy) const; 539 bool isAlignOf(const Type *&AllocTy) const; 540 bool isOffsetOf(const Type *&STy, Constant *&FieldNo) const; 541 542 virtual bool isLoopInvariant(const Loop *L) const; 543 virtual bool hasComputableLoopEvolution(const Loop *QL) const { 544 return false; // not computable 545 } 546 547 virtual bool hasOperand(const SCEV *) const { 548 return false; 549 } 550 551 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 552 553 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 554 555 virtual const Type *getType() const; 556 557 virtual void print(raw_ostream &OS) const; 558 559 /// Methods for support type inquiry through isa, cast, and dyn_cast: 560 static inline bool classof(const SCEVUnknown *S) { return true; } 561 static inline bool classof(const SCEV *S) { 562 return S->getSCEVType() == scUnknown; 563 } 564 }; 565 566 /// SCEVVisitor - This class defines a simple visitor class that may be used 567 /// for various SCEV analysis purposes. 568 template<typename SC, typename RetVal=void> 569 struct SCEVVisitor { 570 RetVal visit(const SCEV *S) { 571 switch (S->getSCEVType()) { 572 case scConstant: 573 return ((SC*)this)->visitConstant((const SCEVConstant*)S); 574 case scTruncate: 575 return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S); 576 case scZeroExtend: 577 return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S); 578 case scSignExtend: 579 return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S); 580 case scAddExpr: 581 return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S); 582 case scMulExpr: 583 return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S); 584 case scUDivExpr: 585 return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S); 586 case scAddRecExpr: 587 return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S); 588 case scSMaxExpr: 589 return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S); 590 case scUMaxExpr: 591 return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S); 592 case scUnknown: 593 return ((SC*)this)->visitUnknown((const SCEVUnknown*)S); 594 case scCouldNotCompute: 595 return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S); 596 default: 597 llvm_unreachable("Unknown SCEV type!"); 598 } 599 } 600 601 RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) { 602 llvm_unreachable("Invalid use of SCEVCouldNotCompute!"); 603 return RetVal(); 604 } 605 }; 606} 607 608#endif 609