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_SCALAREVOLUTIONEXPRESSIONS_H
15 #define LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/FoldingSet.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/iterator_range.h"
22 #include "llvm/Analysis/ScalarEvolution.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/IR/Value.h"
25 #include "llvm/IR/ValueHandle.h"
26 #include "llvm/Support/Casting.h"
27 #include "llvm/Support/ErrorHandling.h"
40 // These should be ordered in terms of increasing complexity to make the
42 scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
43 scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
44 scUnknown, scCouldNotCompute
47 /// This class represents a constant integer value.
48 class SCEVConstant : public SCEV {
49 friend class ScalarEvolution;
53 SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) :
54 SCEV(ID, scConstant), V(v) {}
57 ConstantInt *getValue() const { return V; }
58 const APInt &getAPInt() const { return getValue()->getValue(); }
60 Type *getType() const { return V->getType(); }
62 /// Methods for support type inquiry through isa, cast, and dyn_cast:
63 static bool classof(const SCEV *S) {
64 return S->getSCEVType() == scConstant;
68 /// This is the base class for unary cast operator classes.
69 class SCEVCastExpr : public SCEV {
74 SCEVCastExpr(const FoldingSetNodeIDRef ID,
75 unsigned SCEVTy, const SCEV *op, Type *ty);
78 const SCEV *getOperand() const { return Op; }
79 Type *getType() const { return Ty; }
81 /// Methods for support type inquiry through isa, cast, and dyn_cast:
82 static bool classof(const SCEV *S) {
83 return S->getSCEVType() == scTruncate ||
84 S->getSCEVType() == scZeroExtend ||
85 S->getSCEVType() == scSignExtend;
89 /// This class represents a truncation of an integer value to a
90 /// smaller integer value.
91 class SCEVTruncateExpr : public SCEVCastExpr {
92 friend class ScalarEvolution;
94 SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
95 const SCEV *op, Type *ty);
98 /// Methods for support type inquiry through isa, cast, and dyn_cast:
99 static bool classof(const SCEV *S) {
100 return S->getSCEVType() == scTruncate;
104 /// This class represents a zero extension of a small integer value
105 /// to a larger integer value.
106 class SCEVZeroExtendExpr : public SCEVCastExpr {
107 friend class ScalarEvolution;
109 SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
110 const SCEV *op, Type *ty);
113 /// Methods for support type inquiry through isa, cast, and dyn_cast:
114 static bool classof(const SCEV *S) {
115 return S->getSCEVType() == scZeroExtend;
119 /// This class represents a sign extension of a small integer value
120 /// to a larger integer value.
121 class SCEVSignExtendExpr : public SCEVCastExpr {
122 friend class ScalarEvolution;
124 SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
125 const SCEV *op, Type *ty);
128 /// Methods for support type inquiry through isa, cast, and dyn_cast:
129 static bool classof(const SCEV *S) {
130 return S->getSCEVType() == scSignExtend;
134 /// This node is a base class providing common functionality for
136 class SCEVNAryExpr : public SCEV {
138 // Since SCEVs are immutable, ScalarEvolution allocates operand
139 // arrays with its SCEVAllocator, so this class just needs a simple
140 // pointer rather than a more elaborate vector-like data structure.
141 // This also avoids the need for a non-trivial destructor.
142 const SCEV *const *Operands;
145 SCEVNAryExpr(const FoldingSetNodeIDRef ID,
146 enum SCEVTypes T, const SCEV *const *O, size_t N)
147 : SCEV(ID, T), Operands(O), NumOperands(N) {}
150 size_t getNumOperands() const { return NumOperands; }
152 const SCEV *getOperand(unsigned i) const {
153 assert(i < NumOperands && "Operand index out of range!");
157 using op_iterator = const SCEV *const *;
158 using op_range = iterator_range<op_iterator>;
160 op_iterator op_begin() const { return Operands; }
161 op_iterator op_end() const { return Operands + NumOperands; }
162 op_range operands() const {
163 return make_range(op_begin(), op_end());
166 Type *getType() const { return getOperand(0)->getType(); }
168 NoWrapFlags getNoWrapFlags(NoWrapFlags Mask = NoWrapMask) const {
169 return (NoWrapFlags)(SubclassData & Mask);
172 bool hasNoUnsignedWrap() const {
173 return getNoWrapFlags(FlagNUW) != FlagAnyWrap;
176 bool hasNoSignedWrap() const {
177 return getNoWrapFlags(FlagNSW) != FlagAnyWrap;
180 bool hasNoSelfWrap() const {
181 return getNoWrapFlags(FlagNW) != FlagAnyWrap;
184 /// Methods for support type inquiry through isa, cast, and dyn_cast:
185 static bool classof(const SCEV *S) {
186 return S->getSCEVType() == scAddExpr ||
187 S->getSCEVType() == scMulExpr ||
188 S->getSCEVType() == scSMaxExpr ||
189 S->getSCEVType() == scUMaxExpr ||
190 S->getSCEVType() == scAddRecExpr;
194 /// This node is the base class for n'ary commutative operators.
195 class SCEVCommutativeExpr : public SCEVNAryExpr {
197 SCEVCommutativeExpr(const FoldingSetNodeIDRef ID,
198 enum SCEVTypes T, const SCEV *const *O, size_t N)
199 : SCEVNAryExpr(ID, T, O, N) {}
202 /// Methods for support type inquiry through isa, cast, and dyn_cast:
203 static bool classof(const SCEV *S) {
204 return S->getSCEVType() == scAddExpr ||
205 S->getSCEVType() == scMulExpr ||
206 S->getSCEVType() == scSMaxExpr ||
207 S->getSCEVType() == scUMaxExpr;
210 /// Set flags for a non-recurrence without clearing previously set flags.
211 void setNoWrapFlags(NoWrapFlags Flags) {
212 SubclassData |= Flags;
216 /// This node represents an addition of some number of SCEVs.
217 class SCEVAddExpr : public SCEVCommutativeExpr {
218 friend class ScalarEvolution;
220 SCEVAddExpr(const FoldingSetNodeIDRef ID,
221 const SCEV *const *O, size_t N)
222 : SCEVCommutativeExpr(ID, scAddExpr, O, N) {}
225 Type *getType() const {
226 // Use the type of the last operand, which is likely to be a pointer
227 // type, if there is one. This doesn't usually matter, but it can help
228 // reduce casts when the expressions are expanded.
229 return getOperand(getNumOperands() - 1)->getType();
232 /// Methods for support type inquiry through isa, cast, and dyn_cast:
233 static bool classof(const SCEV *S) {
234 return S->getSCEVType() == scAddExpr;
238 /// This node represents multiplication of some number of SCEVs.
239 class SCEVMulExpr : public SCEVCommutativeExpr {
240 friend class ScalarEvolution;
242 SCEVMulExpr(const FoldingSetNodeIDRef ID,
243 const SCEV *const *O, size_t N)
244 : SCEVCommutativeExpr(ID, scMulExpr, O, N) {}
247 /// Methods for support type inquiry through isa, cast, and dyn_cast:
248 static bool classof(const SCEV *S) {
249 return S->getSCEVType() == scMulExpr;
253 /// This class represents a binary unsigned division operation.
254 class SCEVUDivExpr : public SCEV {
255 friend class ScalarEvolution;
260 SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs)
261 : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {}
264 const SCEV *getLHS() const { return LHS; }
265 const SCEV *getRHS() const { return RHS; }
267 Type *getType() const {
268 // In most cases the types of LHS and RHS will be the same, but in some
269 // crazy cases one or the other may be a pointer. ScalarEvolution doesn't
270 // depend on the type for correctness, but handling types carefully can
271 // avoid extra casts in the SCEVExpander. The LHS is more likely to be
272 // a pointer type than the RHS, so use the RHS' type here.
273 return getRHS()->getType();
276 /// Methods for support type inquiry through isa, cast, and dyn_cast:
277 static bool classof(const SCEV *S) {
278 return S->getSCEVType() == scUDivExpr;
282 /// This node represents a polynomial recurrence on the trip count
283 /// of the specified loop. This is the primary focus of the
284 /// ScalarEvolution framework; all the other SCEV subclasses are
285 /// mostly just supporting infrastructure to allow SCEVAddRecExpr
286 /// expressions to be created and analyzed.
288 /// All operands of an AddRec are required to be loop invariant.
290 class SCEVAddRecExpr : public SCEVNAryExpr {
291 friend class ScalarEvolution;
295 SCEVAddRecExpr(const FoldingSetNodeIDRef ID,
296 const SCEV *const *O, size_t N, const Loop *l)
297 : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {}
300 const SCEV *getStart() const { return Operands[0]; }
301 const Loop *getLoop() const { return L; }
303 /// Constructs and returns the recurrence indicating how much this
304 /// expression steps by. If this is a polynomial of degree N, it
305 /// returns a chrec of degree N-1. We cannot determine whether
306 /// the step recurrence has self-wraparound.
307 const SCEV *getStepRecurrence(ScalarEvolution &SE) const {
308 if (isAffine()) return getOperand(1);
309 return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1,
311 getLoop(), FlagAnyWrap);
314 /// Return true if this represents an expression A + B*x where A
315 /// and B are loop invariant values.
316 bool isAffine() const {
317 // We know that the start value is invariant. This expression is thus
318 // affine iff the step is also invariant.
319 return getNumOperands() == 2;
322 /// Return true if this represents an expression A + B*x + C*x^2
323 /// where A, B and C are loop invariant values. This corresponds
324 /// to an addrec of the form {L,+,M,+,N}
325 bool isQuadratic() const {
326 return getNumOperands() == 3;
329 /// Set flags for a recurrence without clearing any previously set flags.
330 /// For AddRec, either NUW or NSW implies NW. Keep track of this fact here
331 /// to make it easier to propagate flags.
332 void setNoWrapFlags(NoWrapFlags Flags) {
333 if (Flags & (FlagNUW | FlagNSW))
334 Flags = ScalarEvolution::setFlags(Flags, FlagNW);
335 SubclassData |= Flags;
338 /// Return the value of this chain of recurrences at the specified
339 /// iteration number.
340 const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const;
342 /// Return the number of iterations of this loop that produce
343 /// values in the specified constant range. Another way of
344 /// looking at this is that it returns the first iteration number
345 /// where the value is not in the condition, thus computing the
346 /// exit count. If the iteration count can't be computed, an
347 /// instance of SCEVCouldNotCompute is returned.
348 const SCEV *getNumIterationsInRange(const ConstantRange &Range,
349 ScalarEvolution &SE) const;
351 /// Return an expression representing the value of this expression
352 /// one iteration of the loop ahead.
353 const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const {
354 return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE)));
357 /// Methods for support type inquiry through isa, cast, and dyn_cast:
358 static bool classof(const SCEV *S) {
359 return S->getSCEVType() == scAddRecExpr;
363 /// This class represents a signed maximum selection.
364 class SCEVSMaxExpr : public SCEVCommutativeExpr {
365 friend class ScalarEvolution;
367 SCEVSMaxExpr(const FoldingSetNodeIDRef ID,
368 const SCEV *const *O, size_t N)
369 : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
370 // Max never overflows.
371 setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
375 /// Methods for support type inquiry through isa, cast, and dyn_cast:
376 static bool classof(const SCEV *S) {
377 return S->getSCEVType() == scSMaxExpr;
381 /// This class represents an unsigned maximum selection.
382 class SCEVUMaxExpr : public SCEVCommutativeExpr {
383 friend class ScalarEvolution;
385 SCEVUMaxExpr(const FoldingSetNodeIDRef ID,
386 const SCEV *const *O, size_t N)
387 : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
388 // Max never overflows.
389 setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
393 /// Methods for support type inquiry through isa, cast, and dyn_cast:
394 static bool classof(const SCEV *S) {
395 return S->getSCEVType() == scUMaxExpr;
399 /// This means that we are dealing with an entirely unknown SCEV
400 /// value, and only represent it as its LLVM Value. This is the
401 /// "bottom" value for the analysis.
402 class SCEVUnknown final : public SCEV, private CallbackVH {
403 friend class ScalarEvolution;
405 /// The parent ScalarEvolution value. This is used to update the
406 /// parent's maps when the value associated with a SCEVUnknown is
407 /// deleted or RAUW'd.
410 /// The next pointer in the linked list of all SCEVUnknown
411 /// instances owned by a ScalarEvolution.
414 SCEVUnknown(const FoldingSetNodeIDRef ID, Value *V,
415 ScalarEvolution *se, SCEVUnknown *next) :
416 SCEV(ID, scUnknown), CallbackVH(V), SE(se), Next(next) {}
418 // Implement CallbackVH.
419 void deleted() override;
420 void allUsesReplacedWith(Value *New) override;
423 Value *getValue() const { return getValPtr(); }
426 /// Test whether this is a special constant representing a type
427 /// size, alignment, or field offset in a target-independent
428 /// manner, and hasn't happened to have been folded with other
429 /// operations into something unrecognizable. This is mainly only
430 /// useful for pretty-printing and other situations where it isn't
431 /// 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;
437 Type *getType() const { return getValPtr()->getType(); }
439 /// Methods for support type inquiry through isa, cast, and dyn_cast:
440 static bool classof(const SCEV *S) {
441 return S->getSCEVType() == scUnknown;
445 /// This class defines a simple visitor class that may be used for
446 /// various SCEV analysis purposes.
447 template<typename SC, typename RetVal=void>
449 RetVal visit(const SCEV *S) {
450 switch (S->getSCEVType()) {
452 return ((SC*)this)->visitConstant((const SCEVConstant*)S);
454 return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S);
456 return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S);
458 return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S);
460 return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S);
462 return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S);
464 return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S);
466 return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S);
468 return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
470 return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
472 return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
473 case scCouldNotCompute:
474 return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S);
476 llvm_unreachable("Unknown SCEV type!");
480 RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) {
481 llvm_unreachable("Invalid use of SCEVCouldNotCompute!");
485 /// Visit all nodes in the expression tree using worklist traversal.
487 /// Visitor implements:
488 /// // return true to follow this node.
489 /// bool follow(const SCEV *S);
490 /// // return true to terminate the search.
492 template<typename SV>
493 class SCEVTraversal {
495 SmallVector<const SCEV *, 8> Worklist;
496 SmallPtrSet<const SCEV *, 8> Visited;
498 void push(const SCEV *S) {
499 if (Visited.insert(S).second && Visitor.follow(S))
500 Worklist.push_back(S);
504 SCEVTraversal(SV& V): Visitor(V) {}
506 void visitAll(const SCEV *Root) {
508 while (!Worklist.empty() && !Visitor.isDone()) {
509 const SCEV *S = Worklist.pop_back_val();
511 switch (S->getSCEVType()) {
518 push(cast<SCEVCastExpr>(S)->getOperand());
525 for (const auto *Op : cast<SCEVNAryExpr>(S)->operands())
529 const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
530 push(UDiv->getLHS());
531 push(UDiv->getRHS());
534 case scCouldNotCompute:
535 llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
537 llvm_unreachable("Unknown SCEV kind!");
543 /// Use SCEVTraversal to visit all nodes in the given expression tree.
544 template<typename SV>
545 void visitAll(const SCEV *Root, SV& Visitor) {
546 SCEVTraversal<SV> T(Visitor);
550 /// Return true if any node in \p Root satisfies the predicate \p Pred.
551 template <typename PredTy>
552 bool SCEVExprContains(const SCEV *Root, PredTy Pred) {
557 FindClosure(PredTy Pred) : Pred(Pred) {}
559 bool follow(const SCEV *S) {
567 bool isDone() const { return Found; }
570 FindClosure FC(Pred);
575 /// This visitor recursively visits a SCEV expression and re-writes it.
576 /// The result from each visit is cached, so it will return the same
577 /// SCEV for the same input.
578 template<typename SC>
579 class SCEVRewriteVisitor : public SCEVVisitor<SC, const SCEV *> {
582 // Memoize the result of each visit so that we only compute once for
583 // the same input SCEV. This is to avoid redundant computations when
584 // a SCEV is referenced by multiple SCEVs. Without memoization, this
585 // visit algorithm would have exponential time complexity in the worst
586 // case, causing the compiler to hang on certain tests.
587 DenseMap<const SCEV *, const SCEV *> RewriteResults;
590 SCEVRewriteVisitor(ScalarEvolution &SE) : SE(SE) {}
592 const SCEV *visit(const SCEV *S) {
593 auto It = RewriteResults.find(S);
594 if (It != RewriteResults.end())
596 auto* Visited = SCEVVisitor<SC, const SCEV *>::visit(S);
597 auto Result = RewriteResults.try_emplace(S, Visited);
598 assert(Result.second && "Should insert a new entry");
599 return Result.first->second;
602 const SCEV *visitConstant(const SCEVConstant *Constant) {
606 const SCEV *visitTruncateExpr(const SCEVTruncateExpr *Expr) {
607 const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
608 return Operand == Expr->getOperand()
610 : SE.getTruncateExpr(Operand, Expr->getType());
613 const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
614 const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
615 return Operand == Expr->getOperand()
617 : SE.getZeroExtendExpr(Operand, Expr->getType());
620 const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
621 const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
622 return Operand == Expr->getOperand()
624 : SE.getSignExtendExpr(Operand, Expr->getType());
627 const SCEV *visitAddExpr(const SCEVAddExpr *Expr) {
628 SmallVector<const SCEV *, 2> Operands;
629 bool Changed = false;
630 for (auto *Op : Expr->operands()) {
631 Operands.push_back(((SC*)this)->visit(Op));
632 Changed |= Op != Operands.back();
634 return !Changed ? Expr : SE.getAddExpr(Operands);
637 const SCEV *visitMulExpr(const SCEVMulExpr *Expr) {
638 SmallVector<const SCEV *, 2> Operands;
639 bool Changed = false;
640 for (auto *Op : Expr->operands()) {
641 Operands.push_back(((SC*)this)->visit(Op));
642 Changed |= Op != Operands.back();
644 return !Changed ? Expr : SE.getMulExpr(Operands);
647 const SCEV *visitUDivExpr(const SCEVUDivExpr *Expr) {
648 auto *LHS = ((SC *)this)->visit(Expr->getLHS());
649 auto *RHS = ((SC *)this)->visit(Expr->getRHS());
650 bool Changed = LHS != Expr->getLHS() || RHS != Expr->getRHS();
651 return !Changed ? Expr : SE.getUDivExpr(LHS, RHS);
654 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
655 SmallVector<const SCEV *, 2> Operands;
656 bool Changed = false;
657 for (auto *Op : Expr->operands()) {
658 Operands.push_back(((SC*)this)->visit(Op));
659 Changed |= Op != Operands.back();
661 return !Changed ? Expr
662 : SE.getAddRecExpr(Operands, Expr->getLoop(),
663 Expr->getNoWrapFlags());
666 const SCEV *visitSMaxExpr(const SCEVSMaxExpr *Expr) {
667 SmallVector<const SCEV *, 2> Operands;
668 bool Changed = false;
669 for (auto *Op : Expr->operands()) {
670 Operands.push_back(((SC *)this)->visit(Op));
671 Changed |= Op != Operands.back();
673 return !Changed ? Expr : SE.getSMaxExpr(Operands);
676 const SCEV *visitUMaxExpr(const SCEVUMaxExpr *Expr) {
677 SmallVector<const SCEV *, 2> Operands;
678 bool Changed = false;
679 for (auto *Op : Expr->operands()) {
680 Operands.push_back(((SC*)this)->visit(Op));
681 Changed |= Op != Operands.back();
683 return !Changed ? Expr : SE.getUMaxExpr(Operands);
686 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
690 const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
695 using ValueToValueMap = DenseMap<const Value *, Value *>;
697 /// The SCEVParameterRewriter takes a scalar evolution expression and updates
698 /// the SCEVUnknown components following the Map (Value -> Value).
699 class SCEVParameterRewriter : public SCEVRewriteVisitor<SCEVParameterRewriter> {
701 static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE,
702 ValueToValueMap &Map,
703 bool InterpretConsts = false) {
704 SCEVParameterRewriter Rewriter(SE, Map, InterpretConsts);
705 return Rewriter.visit(Scev);
708 SCEVParameterRewriter(ScalarEvolution &SE, ValueToValueMap &M, bool C)
709 : SCEVRewriteVisitor(SE), Map(M), InterpretConsts(C) {}
711 const SCEV *visitUnknown(const SCEVUnknown *Expr) {
712 Value *V = Expr->getValue();
715 if (InterpretConsts && isa<ConstantInt>(NV))
716 return SE.getConstant(cast<ConstantInt>(NV));
717 return SE.getUnknown(NV);
723 ValueToValueMap ⤅
724 bool InterpretConsts;
727 using LoopToScevMapT = DenseMap<const Loop *, const SCEV *>;
729 /// The SCEVLoopAddRecRewriter takes a scalar evolution expression and applies
730 /// the Map (Loop -> SCEV) to all AddRecExprs.
731 class SCEVLoopAddRecRewriter
732 : public SCEVRewriteVisitor<SCEVLoopAddRecRewriter> {
734 SCEVLoopAddRecRewriter(ScalarEvolution &SE, LoopToScevMapT &M)
735 : SCEVRewriteVisitor(SE), Map(M) {}
737 static const SCEV *rewrite(const SCEV *Scev, LoopToScevMapT &Map,
738 ScalarEvolution &SE) {
739 SCEVLoopAddRecRewriter Rewriter(SE, Map);
740 return Rewriter.visit(Scev);
743 const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
744 SmallVector<const SCEV *, 2> Operands;
745 for (const SCEV *Op : Expr->operands())
746 Operands.push_back(visit(Op));
748 const Loop *L = Expr->getLoop();
749 const SCEV *Res = SE.getAddRecExpr(Operands, L, Expr->getNoWrapFlags());
751 if (0 == Map.count(L))
754 const SCEVAddRecExpr *Rec = cast<SCEVAddRecExpr>(Res);
755 return Rec->evaluateAtIteration(Map[L], SE);
762 } // end namespace llvm
764 #endif // LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H