ScalarEvolutionExpressions.h revision dc7a235363166a61e81986c534fe11ceb44109fc
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 for (unsigned i = 0, e = getNumOperands(); i != e; ++i) 207 if (!getOperand(i)->isLoopInvariant(L)) return false; 208 return true; 209 } 210 211 // hasComputableLoopEvolution - N-ary expressions have computable loop 212 // evolutions iff they have at least one operand that varies with the loop, 213 // but that all varying operands are computable. 214 virtual bool hasComputableLoopEvolution(const Loop *L) const { 215 bool HasVarying = false; 216 for (unsigned i = 0, e = getNumOperands(); i != e; ++i) 217 if (!getOperand(i)->isLoopInvariant(L)) { 218 if (getOperand(i)->hasComputableLoopEvolution(L)) 219 HasVarying = true; 220 else 221 return false; 222 } 223 return HasVarying; 224 } 225 226 virtual bool hasOperand(const SCEV *O) const { 227 for (unsigned i = 0, e = getNumOperands(); i != e; ++i) 228 if (O == getOperand(i) || getOperand(i)->hasOperand(O)) 229 return true; 230 return false; 231 } 232 233 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 234 235 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 236 237 virtual const Type *getType() const { return getOperand(0)->getType(); } 238 239 bool hasNoUnsignedWrap() const { return SubclassData & (1 << 0); } 240 void setHasNoUnsignedWrap(bool B) { 241 SubclassData = (SubclassData & ~(1 << 0)) | (B << 0); 242 } 243 bool hasNoSignedWrap() const { return SubclassData & (1 << 1); } 244 void setHasNoSignedWrap(bool B) { 245 SubclassData = (SubclassData & ~(1 << 1)) | (B << 1); 246 } 247 248 /// Methods for support type inquiry through isa, cast, and dyn_cast: 249 static inline bool classof(const SCEVNAryExpr *S) { return true; } 250 static inline bool classof(const SCEV *S) { 251 return S->getSCEVType() == scAddExpr || 252 S->getSCEVType() == scMulExpr || 253 S->getSCEVType() == scSMaxExpr || 254 S->getSCEVType() == scUMaxExpr || 255 S->getSCEVType() == scAddRecExpr; 256 } 257 }; 258 259 //===--------------------------------------------------------------------===// 260 /// SCEVCommutativeExpr - This node is the base class for n'ary commutative 261 /// operators. 262 /// 263 class SCEVCommutativeExpr : public SCEVNAryExpr { 264 protected: 265 SCEVCommutativeExpr(const FoldingSetNodeIDRef ID, 266 enum SCEVTypes T, const SCEV *const *O, size_t N) 267 : SCEVNAryExpr(ID, T, O, N) {} 268 269 public: 270 virtual const char *getOperationStr() const = 0; 271 272 virtual void print(raw_ostream &OS) const; 273 274 /// Methods for support type inquiry through isa, cast, and dyn_cast: 275 static inline bool classof(const SCEVCommutativeExpr *S) { return true; } 276 static inline bool classof(const SCEV *S) { 277 return S->getSCEVType() == scAddExpr || 278 S->getSCEVType() == scMulExpr || 279 S->getSCEVType() == scSMaxExpr || 280 S->getSCEVType() == scUMaxExpr; 281 } 282 }; 283 284 285 //===--------------------------------------------------------------------===// 286 /// SCEVAddExpr - This node represents an addition of some number of SCEVs. 287 /// 288 class SCEVAddExpr : public SCEVCommutativeExpr { 289 friend class ScalarEvolution; 290 291 SCEVAddExpr(const FoldingSetNodeIDRef ID, 292 const SCEV *const *O, size_t N) 293 : SCEVCommutativeExpr(ID, scAddExpr, O, N) { 294 } 295 296 public: 297 virtual const char *getOperationStr() const { return " + "; } 298 299 virtual const Type *getType() const { 300 // Use the type of the last operand, which is likely to be a pointer 301 // type, if there is one. This doesn't usually matter, but it can help 302 // reduce casts when the expressions are expanded. 303 return getOperand(getNumOperands() - 1)->getType(); 304 } 305 306 /// Methods for support type inquiry through isa, cast, and dyn_cast: 307 static inline bool classof(const SCEVAddExpr *S) { return true; } 308 static inline bool classof(const SCEV *S) { 309 return S->getSCEVType() == scAddExpr; 310 } 311 }; 312 313 //===--------------------------------------------------------------------===// 314 /// SCEVMulExpr - This node represents multiplication of some number of SCEVs. 315 /// 316 class SCEVMulExpr : public SCEVCommutativeExpr { 317 friend class ScalarEvolution; 318 319 SCEVMulExpr(const FoldingSetNodeIDRef ID, 320 const SCEV *const *O, size_t N) 321 : SCEVCommutativeExpr(ID, scMulExpr, O, N) { 322 } 323 324 public: 325 virtual const char *getOperationStr() const { return " * "; } 326 327 /// Methods for support type inquiry through isa, cast, and dyn_cast: 328 static inline bool classof(const SCEVMulExpr *S) { return true; } 329 static inline bool classof(const SCEV *S) { 330 return S->getSCEVType() == scMulExpr; 331 } 332 }; 333 334 335 //===--------------------------------------------------------------------===// 336 /// SCEVUDivExpr - This class represents a binary unsigned division operation. 337 /// 338 class SCEVUDivExpr : public SCEV { 339 friend class ScalarEvolution; 340 341 const SCEV *LHS; 342 const SCEV *RHS; 343 SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs) 344 : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {} 345 346 public: 347 const SCEV *getLHS() const { return LHS; } 348 const SCEV *getRHS() const { return RHS; } 349 350 virtual bool isLoopInvariant(const Loop *L) const { 351 return LHS->isLoopInvariant(L) && RHS->isLoopInvariant(L); 352 } 353 354 virtual bool hasComputableLoopEvolution(const Loop *L) const { 355 return LHS->hasComputableLoopEvolution(L) && 356 RHS->hasComputableLoopEvolution(L); 357 } 358 359 virtual bool hasOperand(const SCEV *O) const { 360 return O == LHS || O == RHS || LHS->hasOperand(O) || RHS->hasOperand(O); 361 } 362 363 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 364 365 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 366 367 virtual const Type *getType() const; 368 369 void print(raw_ostream &OS) const; 370 371 /// Methods for support type inquiry through isa, cast, and dyn_cast: 372 static inline bool classof(const SCEVUDivExpr *S) { return true; } 373 static inline bool classof(const SCEV *S) { 374 return S->getSCEVType() == scUDivExpr; 375 } 376 }; 377 378 379 //===--------------------------------------------------------------------===// 380 /// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip 381 /// count of the specified loop. This is the primary focus of the 382 /// ScalarEvolution framework; all the other SCEV subclasses are mostly just 383 /// supporting infrastructure to allow SCEVAddRecExpr expressions to be 384 /// created and analyzed. 385 /// 386 /// All operands of an AddRec are required to be loop invariant. 387 /// 388 class SCEVAddRecExpr : public SCEVNAryExpr { 389 friend class ScalarEvolution; 390 391 const Loop *L; 392 393 SCEVAddRecExpr(const FoldingSetNodeIDRef ID, 394 const SCEV *const *O, size_t N, const Loop *l) 395 : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) { 396 for (size_t i = 0, e = NumOperands; i != e; ++i) 397 assert(Operands[i]->isLoopInvariant(l) && 398 "Operands of AddRec must be loop-invariant!"); 399 } 400 401 public: 402 const SCEV *getStart() const { return Operands[0]; } 403 const Loop *getLoop() const { return L; } 404 405 /// getStepRecurrence - This method constructs and returns the recurrence 406 /// indicating how much this expression steps by. If this is a polynomial 407 /// of degree N, it returns a chrec of degree N-1. 408 const SCEV *getStepRecurrence(ScalarEvolution &SE) const { 409 if (isAffine()) return getOperand(1); 410 return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1, 411 op_end()), 412 getLoop()); 413 } 414 415 virtual bool hasComputableLoopEvolution(const Loop *QL) const { 416 return L == QL; 417 } 418 419 virtual bool isLoopInvariant(const Loop *QueryLoop) const; 420 421 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 422 423 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 424 425 /// isAffine - Return true if this is an affine AddRec (i.e., it represents 426 /// an expressions A+B*x where A and B are loop invariant values. 427 bool isAffine() const { 428 // We know that the start value is invariant. This expression is thus 429 // affine iff the step is also invariant. 430 return getNumOperands() == 2; 431 } 432 433 /// isQuadratic - Return true if this is an quadratic AddRec (i.e., it 434 /// represents an expressions A+B*x+C*x^2 where A, B and C are loop 435 /// invariant values. This corresponds to an addrec of the form {L,+,M,+,N} 436 bool isQuadratic() const { 437 return getNumOperands() == 3; 438 } 439 440 /// evaluateAtIteration - Return the value of this chain of recurrences at 441 /// the specified iteration number. 442 const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const; 443 444 /// getNumIterationsInRange - Return the number of iterations of this loop 445 /// that produce values in the specified constant range. Another way of 446 /// looking at this is that it returns the first iteration number where the 447 /// value is not in the condition, thus computing the exit count. If the 448 /// iteration count can't be computed, an instance of SCEVCouldNotCompute is 449 /// returned. 450 const SCEV *getNumIterationsInRange(ConstantRange Range, 451 ScalarEvolution &SE) const; 452 453 /// getPostIncExpr - Return an expression representing the value of 454 /// this expression one iteration of the loop ahead. 455 const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const { 456 return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE))); 457 } 458 459 virtual void print(raw_ostream &OS) const; 460 461 /// Methods for support type inquiry through isa, cast, and dyn_cast: 462 static inline bool classof(const SCEVAddRecExpr *S) { return true; } 463 static inline bool classof(const SCEV *S) { 464 return S->getSCEVType() == scAddRecExpr; 465 } 466 }; 467 468 469 //===--------------------------------------------------------------------===// 470 /// SCEVSMaxExpr - This class represents a signed maximum selection. 471 /// 472 class SCEVSMaxExpr : public SCEVCommutativeExpr { 473 friend class ScalarEvolution; 474 475 SCEVSMaxExpr(const FoldingSetNodeIDRef ID, 476 const SCEV *const *O, size_t N) 477 : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) { 478 // Max never overflows. 479 setHasNoUnsignedWrap(true); 480 setHasNoSignedWrap(true); 481 } 482 483 public: 484 virtual const char *getOperationStr() const { return " smax "; } 485 486 /// Methods for support type inquiry through isa, cast, and dyn_cast: 487 static inline bool classof(const SCEVSMaxExpr *S) { return true; } 488 static inline bool classof(const SCEV *S) { 489 return S->getSCEVType() == scSMaxExpr; 490 } 491 }; 492 493 494 //===--------------------------------------------------------------------===// 495 /// SCEVUMaxExpr - This class represents an unsigned maximum selection. 496 /// 497 class SCEVUMaxExpr : public SCEVCommutativeExpr { 498 friend class ScalarEvolution; 499 500 SCEVUMaxExpr(const FoldingSetNodeIDRef ID, 501 const SCEV *const *O, size_t N) 502 : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) { 503 // Max never overflows. 504 setHasNoUnsignedWrap(true); 505 setHasNoSignedWrap(true); 506 } 507 508 public: 509 virtual const char *getOperationStr() const { return " umax "; } 510 511 /// Methods for support type inquiry through isa, cast, and dyn_cast: 512 static inline bool classof(const SCEVUMaxExpr *S) { return true; } 513 static inline bool classof(const SCEV *S) { 514 return S->getSCEVType() == scUMaxExpr; 515 } 516 }; 517 518 //===--------------------------------------------------------------------===// 519 /// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV 520 /// value, and only represent it as its LLVM Value. This is the "bottom" 521 /// value for the analysis. 522 /// 523 class SCEVUnknown : public SCEV { 524 friend class ScalarEvolution; 525 friend class ScalarEvolution::SCEVCallbackVH; 526 527 // This should be an AssertingVH, however SCEVUnknowns are allocated in a 528 // BumpPtrAllocator so their destructors are never called. 529 Value *V; 530 SCEVUnknown(const FoldingSetNodeIDRef ID, Value *v) : 531 SCEV(ID, scUnknown), V(v) {} 532 533 public: 534 Value *getValue() const { return V; } 535 536 /// isSizeOf, isAlignOf, isOffsetOf - Test whether this is a special 537 /// constant representing a type size, alignment, or field offset in 538 /// a target-independent manner, and hasn't happened to have been 539 /// folded with other operations into something unrecognizable. This 540 /// is mainly only useful for pretty-printing and other situations 541 /// where it isn't absolutely required for these to succeed. 542 bool isSizeOf(const Type *&AllocTy) const; 543 bool isAlignOf(const Type *&AllocTy) const; 544 bool isOffsetOf(const Type *&STy, Constant *&FieldNo) const; 545 546 virtual bool isLoopInvariant(const Loop *L) const; 547 virtual bool hasComputableLoopEvolution(const Loop *QL) const { 548 return false; // not computable 549 } 550 551 virtual bool hasOperand(const SCEV *) const { 552 return false; 553 } 554 555 bool dominates(BasicBlock *BB, DominatorTree *DT) const; 556 557 bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const; 558 559 virtual const Type *getType() const; 560 561 virtual void print(raw_ostream &OS) const; 562 563 /// Methods for support type inquiry through isa, cast, and dyn_cast: 564 static inline bool classof(const SCEVUnknown *S) { return true; } 565 static inline bool classof(const SCEV *S) { 566 return S->getSCEVType() == scUnknown; 567 } 568 }; 569 570 /// SCEVVisitor - This class defines a simple visitor class that may be used 571 /// for various SCEV analysis purposes. 572 template<typename SC, typename RetVal=void> 573 struct SCEVVisitor { 574 RetVal visit(const SCEV *S) { 575 switch (S->getSCEVType()) { 576 case scConstant: 577 return ((SC*)this)->visitConstant((const SCEVConstant*)S); 578 case scTruncate: 579 return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S); 580 case scZeroExtend: 581 return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S); 582 case scSignExtend: 583 return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S); 584 case scAddExpr: 585 return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S); 586 case scMulExpr: 587 return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S); 588 case scUDivExpr: 589 return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S); 590 case scAddRecExpr: 591 return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S); 592 case scSMaxExpr: 593 return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S); 594 case scUMaxExpr: 595 return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S); 596 case scUnknown: 597 return ((SC*)this)->visitUnknown((const SCEVUnknown*)S); 598 case scCouldNotCompute: 599 return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S); 600 default: 601 llvm_unreachable("Unknown SCEV type!"); 602 } 603 } 604 605 RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) { 606 llvm_unreachable("Invalid use of SCEVCouldNotCompute!"); 607 return RetVal(); 608 } 609 }; 610} 611 612#endif 613