1 //===- llvm/Analysis/ScalarEvolutionExpressions.h - SCEV Exprs --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the classes used to represent and build scalar expressions.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
15 #define LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
17 #include "llvm/Analysis/ScalarEvolution.h"
18 #include "llvm/ADT/SmallPtrSet.h"
19 #include "llvm/Support/ErrorHandling.h"
27 // These should be ordered in terms of increasing complexity to make the
29 scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
30 scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
31 scUnknown, scCouldNotCompute
34 //===--------------------------------------------------------------------===//
35 /// SCEVConstant - This class represents a constant integer value.
37 class SCEVConstant : public SCEV {
38 friend class ScalarEvolution;
41 SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) :
42 SCEV(ID, scConstant), V(v) {}
44 ConstantInt *getValue() const { return V; }
46 Type *getType() const { return V->getType(); }
48 /// Methods for support type inquiry through isa, cast, and dyn_cast:
49 static inline bool classof(const SCEV *S) {
50 return S->getSCEVType() == scConstant;
54 //===--------------------------------------------------------------------===//
55 /// SCEVCastExpr - This is the base class for unary cast operator classes.
57 class SCEVCastExpr : public SCEV {
62 SCEVCastExpr(const FoldingSetNodeIDRef ID,
63 unsigned SCEVTy, const SCEV *op, Type *ty);
66 const SCEV *getOperand() const { return Op; }
67 Type *getType() const { return Ty; }
69 /// Methods for support type inquiry through isa, cast, and dyn_cast:
70 static inline bool classof(const SCEV *S) {
71 return S->getSCEVType() == scTruncate ||
72 S->getSCEVType() == scZeroExtend ||
73 S->getSCEVType() == scSignExtend;
77 //===--------------------------------------------------------------------===//
78 /// SCEVTruncateExpr - This class represents a truncation of an integer value
79 /// to a smaller integer value.
81 class SCEVTruncateExpr : public SCEVCastExpr {
82 friend class ScalarEvolution;
84 SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
85 const SCEV *op, Type *ty);
88 /// Methods for support type inquiry through isa, cast, and dyn_cast:
89 static inline bool classof(const SCEV *S) {
90 return S->getSCEVType() == scTruncate;
94 //===--------------------------------------------------------------------===//
95 /// SCEVZeroExtendExpr - This class represents a zero extension of a small
96 /// integer value to a larger integer value.
98 class SCEVZeroExtendExpr : public SCEVCastExpr {
99 friend class ScalarEvolution;
101 SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
102 const SCEV *op, Type *ty);
105 /// Methods for support type inquiry through isa, cast, and dyn_cast:
106 static inline bool classof(const SCEV *S) {
107 return S->getSCEVType() == scZeroExtend;
111 //===--------------------------------------------------------------------===//
112 /// SCEVSignExtendExpr - This class represents a sign extension of a small
113 /// integer value to a larger integer value.
115 class SCEVSignExtendExpr : public SCEVCastExpr {
116 friend class ScalarEvolution;
118 SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
119 const SCEV *op, Type *ty);
122 /// Methods for support type inquiry through isa, cast, and dyn_cast:
123 static inline bool classof(const SCEV *S) {
124 return S->getSCEVType() == scSignExtend;
129 //===--------------------------------------------------------------------===//
130 /// SCEVNAryExpr - This node is a base class providing common
131 /// functionality for n'ary operators.
133 class SCEVNAryExpr : public SCEV {
135 // Since SCEVs are immutable, ScalarEvolution allocates operand
136 // arrays with its SCEVAllocator, so this class just needs a simple
137 // pointer rather than a more elaborate vector-like data structure.
138 // This also avoids the need for a non-trivial destructor.
139 const SCEV *const *Operands;
142 SCEVNAryExpr(const FoldingSetNodeIDRef ID,
143 enum SCEVTypes T, const SCEV *const *O, size_t N)
144 : SCEV(ID, T), Operands(O), NumOperands(N) {}
147 size_t getNumOperands() const { return NumOperands; }
148 const SCEV *getOperand(unsigned i) const {
149 assert(i < NumOperands && "Operand index out of range!");
153 typedef const SCEV *const *op_iterator;
154 op_iterator op_begin() const { return Operands; }
155 op_iterator op_end() const { return Operands + NumOperands; }
157 Type *getType() const { return getOperand(0)->getType(); }
159 NoWrapFlags getNoWrapFlags(NoWrapFlags Mask = NoWrapMask) const {
160 return (NoWrapFlags)(SubclassData & Mask);
163 /// Methods for support type inquiry through isa, cast, and dyn_cast:
164 static inline bool classof(const SCEV *S) {
165 return S->getSCEVType() == scAddExpr ||
166 S->getSCEVType() == scMulExpr ||
167 S->getSCEVType() == scSMaxExpr ||
168 S->getSCEVType() == scUMaxExpr ||
169 S->getSCEVType() == scAddRecExpr;
173 //===--------------------------------------------------------------------===//
174 /// SCEVCommutativeExpr - This node is the base class for n'ary commutative
177 class SCEVCommutativeExpr : public SCEVNAryExpr {
179 SCEVCommutativeExpr(const FoldingSetNodeIDRef ID,
180 enum SCEVTypes T, const SCEV *const *O, size_t N)
181 : SCEVNAryExpr(ID, T, O, N) {}
184 /// Methods for support type inquiry through isa, cast, and dyn_cast:
185 static inline bool classof(const SCEV *S) {
186 return S->getSCEVType() == scAddExpr ||
187 S->getSCEVType() == scMulExpr ||
188 S->getSCEVType() == scSMaxExpr ||
189 S->getSCEVType() == scUMaxExpr;
192 /// Set flags for a non-recurrence without clearing previously set flags.
193 void setNoWrapFlags(NoWrapFlags Flags) {
194 SubclassData |= Flags;
199 //===--------------------------------------------------------------------===//
200 /// SCEVAddExpr - This node represents an addition of some number of SCEVs.
202 class SCEVAddExpr : public SCEVCommutativeExpr {
203 friend class ScalarEvolution;
205 SCEVAddExpr(const FoldingSetNodeIDRef ID,
206 const SCEV *const *O, size_t N)
207 : SCEVCommutativeExpr(ID, scAddExpr, O, N) {
211 Type *getType() const {
212 // Use the type of the last operand, which is likely to be a pointer
213 // type, if there is one. This doesn't usually matter, but it can help
214 // reduce casts when the expressions are expanded.
215 return getOperand(getNumOperands() - 1)->getType();
218 /// Methods for support type inquiry through isa, cast, and dyn_cast:
219 static inline bool classof(const SCEV *S) {
220 return S->getSCEVType() == scAddExpr;
224 //===--------------------------------------------------------------------===//
225 /// SCEVMulExpr - This node represents multiplication of some number of SCEVs.
227 class SCEVMulExpr : public SCEVCommutativeExpr {
228 friend class ScalarEvolution;
230 SCEVMulExpr(const FoldingSetNodeIDRef ID,
231 const SCEV *const *O, size_t N)
232 : SCEVCommutativeExpr(ID, scMulExpr, O, N) {
236 /// Methods for support type inquiry through isa, cast, and dyn_cast:
237 static inline bool classof(const SCEV *S) {
238 return S->getSCEVType() == scMulExpr;
243 //===--------------------------------------------------------------------===//
244 /// SCEVUDivExpr - This class represents a binary unsigned division operation.
246 class SCEVUDivExpr : public SCEV {
247 friend class ScalarEvolution;
251 SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs)
252 : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {}
255 const SCEV *getLHS() const { return LHS; }
256 const SCEV *getRHS() const { return RHS; }
258 Type *getType() const {
259 // In most cases the types of LHS and RHS will be the same, but in some
260 // crazy cases one or the other may be a pointer. ScalarEvolution doesn't
261 // depend on the type for correctness, but handling types carefully can
262 // avoid extra casts in the SCEVExpander. The LHS is more likely to be
263 // a pointer type than the RHS, so use the RHS' type here.
264 return getRHS()->getType();
267 /// Methods for support type inquiry through isa, cast, and dyn_cast:
268 static inline bool classof(const SCEV *S) {
269 return S->getSCEVType() == scUDivExpr;
274 //===--------------------------------------------------------------------===//
275 /// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip
276 /// count of the specified loop. This is the primary focus of the
277 /// ScalarEvolution framework; all the other SCEV subclasses are mostly just
278 /// supporting infrastructure to allow SCEVAddRecExpr expressions to be
279 /// created and analyzed.
281 /// All operands of an AddRec are required to be loop invariant.
283 class SCEVAddRecExpr : public SCEVNAryExpr {
284 friend class ScalarEvolution;
288 SCEVAddRecExpr(const FoldingSetNodeIDRef ID,
289 const SCEV *const *O, size_t N, const Loop *l)
290 : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {}
293 const SCEV *getStart() const { return Operands[0]; }
294 const Loop *getLoop() const { return L; }
296 /// getStepRecurrence - This method constructs and returns the recurrence
297 /// indicating how much this expression steps by. If this is a polynomial
298 /// of degree N, it returns a chrec of degree N-1.
299 /// We cannot determine whether the step recurrence has self-wraparound.
300 const SCEV *getStepRecurrence(ScalarEvolution &SE) const {
301 if (isAffine()) return getOperand(1);
302 return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1,
304 getLoop(), FlagAnyWrap);
307 /// isAffine - Return true if this is an affine AddRec (i.e., it represents
308 /// an expressions A+B*x where A and B are loop invariant values.
309 bool isAffine() const {
310 // We know that the start value is invariant. This expression is thus
311 // affine iff the step is also invariant.
312 return getNumOperands() == 2;
315 /// isQuadratic - Return true if this is an quadratic AddRec (i.e., it
316 /// represents an expressions A+B*x+C*x^2 where A, B and C are loop
317 /// invariant values. This corresponds to an addrec of the form {L,+,M,+,N}
318 bool isQuadratic() const {
319 return getNumOperands() == 3;
322 /// Set flags for a recurrence without clearing any previously set flags.
323 /// For AddRec, either NUW or NSW implies NW. Keep track of this fact here
324 /// to make it easier to propagate flags.
325 void setNoWrapFlags(NoWrapFlags Flags) {
326 if (Flags & (FlagNUW | FlagNSW))
327 Flags = ScalarEvolution::setFlags(Flags, FlagNW);
328 SubclassData |= Flags;
331 /// evaluateAtIteration - Return the value of this chain of recurrences at
332 /// the specified iteration number.
333 const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const;
335 /// getNumIterationsInRange - Return the number of iterations of this loop
336 /// that produce values in the specified constant range. Another way of
337 /// looking at this is that it returns the first iteration number where the
338 /// value is not in the condition, thus computing the exit count. If the
339 /// iteration count can't be computed, an instance of SCEVCouldNotCompute is
341 const SCEV *getNumIterationsInRange(ConstantRange Range,
342 ScalarEvolution &SE) const;
344 /// getPostIncExpr - Return an expression representing the value of
345 /// this expression one iteration of the loop ahead.
346 const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const {
347 return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE)));
350 /// Methods for support type inquiry through isa, cast, and dyn_cast:
351 static inline bool classof(const SCEV *S) {
352 return S->getSCEVType() == scAddRecExpr;
357 //===--------------------------------------------------------------------===//
358 /// SCEVSMaxExpr - This class represents a signed maximum selection.
360 class SCEVSMaxExpr : public SCEVCommutativeExpr {
361 friend class ScalarEvolution;
363 SCEVSMaxExpr(const FoldingSetNodeIDRef ID,
364 const SCEV *const *O, size_t N)
365 : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
366 // Max never overflows.
367 setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
371 /// Methods for support type inquiry through isa, cast, and dyn_cast:
372 static inline bool classof(const SCEV *S) {
373 return S->getSCEVType() == scSMaxExpr;
378 //===--------------------------------------------------------------------===//
379 /// SCEVUMaxExpr - This class represents an unsigned maximum selection.
381 class SCEVUMaxExpr : public SCEVCommutativeExpr {
382 friend class ScalarEvolution;
384 SCEVUMaxExpr(const FoldingSetNodeIDRef ID,
385 const SCEV *const *O, size_t N)
386 : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
387 // Max never overflows.
388 setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
392 /// Methods for support type inquiry through isa, cast, and dyn_cast:
393 static inline bool classof(const SCEV *S) {
394 return S->getSCEVType() == scUMaxExpr;
398 //===--------------------------------------------------------------------===//
399 /// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
400 /// value, and only represent it as its LLVM Value. This is the "bottom"
401 /// value for the analysis.
403 class SCEVUnknown : public SCEV, private CallbackVH {
404 friend class ScalarEvolution;
406 // Implement CallbackVH.
407 virtual void deleted();
408 virtual void allUsesReplacedWith(Value *New);
410 /// SE - The parent ScalarEvolution value. This is used to update
411 /// the parent's maps when the value associated with a SCEVUnknown
412 /// is deleted or RAUW'd.
415 /// Next - The next pointer in the linked list of all
416 /// SCEVUnknown instances owned by a ScalarEvolution.
419 SCEVUnknown(const FoldingSetNodeIDRef ID, Value *V,
420 ScalarEvolution *se, SCEVUnknown *next) :
421 SCEV(ID, scUnknown), CallbackVH(V), SE(se), Next(next) {}
424 Value *getValue() const { return getValPtr(); }
426 /// isSizeOf, isAlignOf, isOffsetOf - Test whether this is a special
427 /// constant representing a type size, alignment, or field offset in
428 /// a target-independent manner, and hasn't happened to have been
429 /// folded with other operations into something unrecognizable. This
430 /// is mainly only useful for pretty-printing and other situations
431 /// where it isn't absolutely required for these to succeed.
432 bool isSizeOf(Type *&AllocTy) const;
433 bool isAlignOf(Type *&AllocTy) const;
434 bool isOffsetOf(Type *&STy, Constant *&FieldNo) const;
436 Type *getType() const { return getValPtr()->getType(); }
438 /// Methods for support type inquiry through isa, cast, and dyn_cast:
439 static inline bool classof(const SCEV *S) {
440 return S->getSCEVType() == scUnknown;
444 /// SCEVVisitor - This class defines a simple visitor class that may be used
445 /// for various SCEV analysis purposes.
446 template<typename SC, typename RetVal=void>
448 RetVal visit(const SCEV *S) {
449 switch (S->getSCEVType()) {
451 return ((SC*)this)->visitConstant((const SCEVConstant*)S);
453 return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S);
455 return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S);
457 return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S);
459 return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S);
461 return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S);
463 return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S);
465 return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S);
467 return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
469 return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
471 return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
472 case scCouldNotCompute:
473 return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S);
475 llvm_unreachable("Unknown SCEV type!");
479 RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) {
480 llvm_unreachable("Invalid use of SCEVCouldNotCompute!");
484 /// Visit all nodes in the expression tree using worklist traversal.
486 /// Visitor implements:
487 /// // return true to follow this node.
488 /// bool follow(const SCEV *S);
489 /// // return true to terminate the search.
491 template<typename SV>
492 class SCEVTraversal {
494 SmallVector<const SCEV *, 8> Worklist;
495 SmallPtrSet<const SCEV *, 8> Visited;
497 void push(const SCEV *S) {
498 if (Visited.insert(S) && Visitor.follow(S))
499 Worklist.push_back(S);
502 SCEVTraversal(SV& V): Visitor(V) {}
504 void visitAll(const SCEV *Root) {
506 while (!Worklist.empty() && !Visitor.isDone()) {
507 const SCEV *S = Worklist.pop_back_val();
509 switch (S->getSCEVType()) {
516 push(cast<SCEVCastExpr>(S)->getOperand());
523 const SCEVNAryExpr *NAry = cast<SCEVNAryExpr>(S);
524 for (SCEVNAryExpr::op_iterator I = NAry->op_begin(),
525 E = NAry->op_end(); I != E; ++I) {
531 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
532 push(UDiv->getLHS());
533 push(UDiv->getRHS());
536 case scCouldNotCompute:
537 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
539 llvm_unreachable("Unknown SCEV kind!");
545 /// Use SCEVTraversal to visit all nodes in the givien expression tree.
546 template<typename SV>
547 void visitAll(const SCEV *Root, SV& Visitor) {
548 SCEVTraversal<SV> T(Visitor);