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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_SCALAREVOLUTIONEXPRESSIONS_H
15 : #define LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H
16 :
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"
28 : #include <cassert>
29 : #include <cstddef>
30 :
31 : namespace llvm {
32 :
33 : class APInt;
34 : class Constant;
35 : class ConstantRange;
36 : class Loop;
37 : class Type;
38 :
39 : enum SCEVTypes {
40 : // These should be ordered in terms of increasing complexity to make the
41 : // folders simpler.
42 : scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
43 : scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
44 : scUnknown, scCouldNotCompute
45 : };
46 :
47 : /// This class represents a constant integer value.
48 : class SCEVConstant : public SCEV {
49 : friend class ScalarEvolution;
50 :
51 : ConstantInt *V;
52 :
53 413480 : SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) :
54 413480 : SCEV(ID, scConstant), V(v) {}
55 :
56 : public:
57 0 : ConstantInt *getValue() const { return V; }
58 13250311 : const APInt &getAPInt() const { return getValue()->getValue(); }
59 :
60 0 : Type *getType() const { return V->getType(); }
61 :
62 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
63 : static bool classof(const SCEV *S) {
64 21484356 : return S->getSCEVType() == scConstant;
65 : }
66 : };
67 :
68 : /// This is the base class for unary cast operator classes.
69 : class SCEVCastExpr : public SCEV {
70 : protected:
71 : const SCEV *Op;
72 : Type *Ty;
73 :
74 : SCEVCastExpr(const FoldingSetNodeIDRef ID,
75 : unsigned SCEVTy, const SCEV *op, Type *ty);
76 :
77 : public:
78 0 : const SCEV *getOperand() const { return Op; }
79 0 : Type *getType() const { return Ty; }
80 :
81 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
82 : static bool classof(const SCEV *S) {
83 147149 : return S->getSCEVType() == scTruncate ||
84 290886 : S->getSCEVType() == scZeroExtend ||
85 : S->getSCEVType() == scSignExtend;
86 : }
87 : };
88 :
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;
93 :
94 : SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
95 : const SCEV *op, Type *ty);
96 :
97 : public:
98 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
99 : static bool classof(const SCEV *S) {
100 142541 : return S->getSCEVType() == scTruncate;
101 : }
102 : };
103 :
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;
108 :
109 : SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
110 : const SCEV *op, Type *ty);
111 :
112 : public:
113 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
114 : static bool classof(const SCEV *S) {
115 19154 : return S->getSCEVType() == scZeroExtend;
116 : }
117 : };
118 :
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;
123 :
124 : SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
125 : const SCEV *op, Type *ty);
126 :
127 : public:
128 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
129 : static bool classof(const SCEV *S) {
130 44235 : return S->getSCEVType() == scSignExtend;
131 : }
132 : };
133 :
134 : /// This node is a base class providing common functionality for
135 : /// n'ary operators.
136 : class SCEVNAryExpr : public SCEV {
137 : protected:
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;
143 : size_t NumOperands;
144 :
145 : SCEVNAryExpr(const FoldingSetNodeIDRef ID,
146 : enum SCEVTypes T, const SCEV *const *O, size_t N)
147 832412 : : SCEV(ID, T), Operands(O), NumOperands(N) {}
148 :
149 : public:
150 0 : size_t getNumOperands() const { return NumOperands; }
151 :
152 0 : const SCEV *getOperand(unsigned i) const {
153 : assert(i < NumOperands && "Operand index out of range!");
154 19873179 : return Operands[i];
155 : }
156 :
157 : using op_iterator = const SCEV *const *;
158 : using op_range = iterator_range<op_iterator>;
159 :
160 0 : op_iterator op_begin() const { return Operands; }
161 2325668 : op_iterator op_end() const { return Operands + NumOperands; }
162 : op_range operands() const {
163 14919233 : return make_range(op_begin(), op_end());
164 : }
165 :
166 2054883 : Type *getType() const { return getOperand(0)->getType(); }
167 :
168 0 : NoWrapFlags getNoWrapFlags(NoWrapFlags Mask = NoWrapMask) const {
169 584936 : return (NoWrapFlags)(SubclassData & Mask);
170 : }
171 :
172 : bool hasNoUnsignedWrap() const {
173 409291 : return getNoWrapFlags(FlagNUW) != FlagAnyWrap;
174 : }
175 :
176 : bool hasNoSignedWrap() const {
177 408558 : return getNoWrapFlags(FlagNSW) != FlagAnyWrap;
178 : }
179 :
180 : bool hasNoSelfWrap() const {
181 6449 : return getNoWrapFlags(FlagNW) != FlagAnyWrap;
182 : }
183 :
184 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
185 : static bool classof(const SCEV *S) {
186 346568 : return S->getSCEVType() == scAddExpr ||
187 295968 : S->getSCEVType() == scMulExpr ||
188 294991 : S->getSCEVType() == scSMaxExpr ||
189 662856 : S->getSCEVType() == scUMaxExpr ||
190 : S->getSCEVType() == scAddRecExpr;
191 : }
192 : };
193 :
194 : /// This node is the base class for n'ary commutative operators.
195 : class SCEVCommutativeExpr : public SCEVNAryExpr {
196 : protected:
197 : SCEVCommutativeExpr(const FoldingSetNodeIDRef ID,
198 : enum SCEVTypes T, const SCEV *const *O, size_t N)
199 : : SCEVNAryExpr(ID, T, O, N) {}
200 :
201 : public:
202 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
203 : static bool classof(const SCEV *S) {
204 93313 : return S->getSCEVType() == scAddExpr ||
205 63204 : S->getSCEVType() == scMulExpr ||
206 193870 : S->getSCEVType() == scSMaxExpr ||
207 : S->getSCEVType() == scUMaxExpr;
208 : }
209 :
210 : /// Set flags for a non-recurrence without clearing previously set flags.
211 0 : void setNoWrapFlags(NoWrapFlags Flags) {
212 1092438 : SubclassData |= Flags;
213 0 : }
214 : };
215 :
216 : /// This node represents an addition of some number of SCEVs.
217 : class SCEVAddExpr : public SCEVCommutativeExpr {
218 : friend class ScalarEvolution;
219 :
220 : SCEVAddExpr(const FoldingSetNodeIDRef ID,
221 : const SCEV *const *O, size_t N)
222 : : SCEVCommutativeExpr(ID, scAddExpr, O, N) {}
223 :
224 : public:
225 1041278 : 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 1060845 : return getOperand(getNumOperands() - 1)->getType();
230 : }
231 :
232 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
233 : static bool classof(const SCEV *S) {
234 6988226 : return S->getSCEVType() == scAddExpr;
235 : }
236 : };
237 :
238 : /// This node represents multiplication of some number of SCEVs.
239 : class SCEVMulExpr : public SCEVCommutativeExpr {
240 : friend class ScalarEvolution;
241 :
242 : SCEVMulExpr(const FoldingSetNodeIDRef ID,
243 : const SCEV *const *O, size_t N)
244 : : SCEVCommutativeExpr(ID, scMulExpr, O, N) {}
245 :
246 : public:
247 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
248 : static bool classof(const SCEV *S) {
249 11239170 : return S->getSCEVType() == scMulExpr;
250 : }
251 : };
252 :
253 : /// This class represents a binary unsigned division operation.
254 : class SCEVUDivExpr : public SCEV {
255 : friend class ScalarEvolution;
256 :
257 : const SCEV *LHS;
258 : const SCEV *RHS;
259 :
260 : SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs)
261 22928 : : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {}
262 :
263 : public:
264 0 : const SCEV *getLHS() const { return LHS; }
265 0 : const SCEV *getRHS() const { return RHS; }
266 :
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 78591 : return getRHS()->getType();
274 : }
275 :
276 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
277 : static bool classof(const SCEV *S) {
278 84134 : return S->getSCEVType() == scUDivExpr;
279 : }
280 : };
281 :
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.
287 : ///
288 : /// All operands of an AddRec are required to be loop invariant.
289 : ///
290 : class SCEVAddRecExpr : public SCEVNAryExpr {
291 : friend class ScalarEvolution;
292 :
293 : const Loop *L;
294 :
295 : SCEVAddRecExpr(const FoldingSetNodeIDRef ID,
296 : const SCEV *const *O, size_t N, const Loop *l)
297 380412 : : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {}
298 :
299 : public:
300 1242672 : const SCEV *getStart() const { return Operands[0]; }
301 0 : const Loop *getLoop() const { return L; }
302 :
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 807696 : const SCEV *getStepRecurrence(ScalarEvolution &SE) const {
308 807554 : if (isAffine()) return getOperand(1);
309 284 : return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1,
310 : op_end()),
311 : getLoop(), FlagAnyWrap);
312 : }
313 :
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 1561570 : return getNumOperands() == 2;
320 : }
321 :
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 7752 : return getNumOperands() == 3;
327 : }
328 :
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 0 : void setNoWrapFlags(NoWrapFlags Flags) {
333 815027 : if (Flags & (FlagNUW | FlagNSW))
334 : Flags = ScalarEvolution::setFlags(Flags, FlagNW);
335 827947 : SubclassData |= Flags;
336 0 : }
337 :
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;
341 :
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;
350 :
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 :
355 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
356 : static bool classof(const SCEV *S) {
357 3736890 : return S->getSCEVType() == scAddRecExpr;
358 : }
359 : };
360 :
361 : /// This class represents a signed maximum selection.
362 : class SCEVSMaxExpr : public SCEVCommutativeExpr {
363 : friend class ScalarEvolution;
364 :
365 : SCEVSMaxExpr(const FoldingSetNodeIDRef ID,
366 : const SCEV *const *O, size_t N)
367 : : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
368 : // Max never overflows.
369 : setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
370 : }
371 :
372 : public:
373 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
374 : static bool classof(const SCEV *S) {
375 45398 : return S->getSCEVType() == scSMaxExpr;
376 : }
377 : };
378 :
379 : /// This class represents an unsigned maximum selection.
380 : class SCEVUMaxExpr : public SCEVCommutativeExpr {
381 : friend class ScalarEvolution;
382 :
383 : SCEVUMaxExpr(const FoldingSetNodeIDRef ID,
384 : const SCEV *const *O, size_t N)
385 : : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
386 : // Max never overflows.
387 : setNoWrapFlags((NoWrapFlags)(FlagNUW | FlagNSW));
388 : }
389 :
390 : public:
391 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
392 : static bool classof(const SCEV *S) {
393 57648 : return S->getSCEVType() == scUMaxExpr;
394 : }
395 : };
396 :
397 : /// This means that we are dealing with an entirely unknown SCEV
398 : /// value, and only represent it as its LLVM Value. This is the
399 : /// "bottom" value for the analysis.
400 227022 : class SCEVUnknown final : public SCEV, private CallbackVH {
401 : friend class ScalarEvolution;
402 :
403 : /// The parent ScalarEvolution value. This is used to update the
404 : /// parent's maps when the value associated with a SCEVUnknown is
405 : /// deleted or RAUW'd.
406 : ScalarEvolution *SE;
407 :
408 : /// The next pointer in the linked list of all SCEVUnknown
409 : /// instances owned by a ScalarEvolution.
410 : SCEVUnknown *Next;
411 :
412 227236 : SCEVUnknown(const FoldingSetNodeIDRef ID, Value *V,
413 227236 : ScalarEvolution *se, SCEVUnknown *next) :
414 227236 : SCEV(ID, scUnknown), CallbackVH(V), SE(se), Next(next) {}
415 :
416 : // Implement CallbackVH.
417 : void deleted() override;
418 : void allUsesReplacedWith(Value *New) override;
419 :
420 : public:
421 4312086 : Value *getValue() const { return getValPtr(); }
422 :
423 : /// @{
424 : /// Test whether this is a special constant representing a type
425 : /// size, alignment, or field offset in a target-independent
426 : /// manner, and hasn't happened to have been folded with other
427 : /// operations into something unrecognizable. This is mainly only
428 : /// useful for pretty-printing and other situations where it isn't
429 : /// absolutely required for these to succeed.
430 : bool isSizeOf(Type *&AllocTy) const;
431 : bool isAlignOf(Type *&AllocTy) const;
432 : bool isOffsetOf(Type *&STy, Constant *&FieldNo) const;
433 : /// @}
434 :
435 2371309 : Type *getType() const { return getValPtr()->getType(); }
436 :
437 : /// Methods for support type inquiry through isa, cast, and dyn_cast:
438 : static bool classof(const SCEV *S) {
439 2110664 : return S->getSCEVType() == scUnknown;
440 : }
441 : };
442 :
443 : /// This class defines a simple visitor class that may be used for
444 : /// various SCEV analysis purposes.
445 : template<typename SC, typename RetVal=void>
446 : struct SCEVVisitor {
447 1000292 : RetVal visit(const SCEV *S) {
448 2000584 : switch (S->getSCEVType()) {
449 14216 : case scConstant:
450 31709 : return ((SC*)this)->visitConstant((const SCEVConstant*)S);
451 3396 : case scTruncate:
452 3396 : return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S);
453 7191 : case scZeroExtend:
454 7191 : return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S);
455 3974 : case scSignExtend:
456 3974 : return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S);
457 88871 : case scAddExpr:
458 88871 : return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S);
459 44269 : case scMulExpr:
460 44269 : return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S);
461 6596 : case scUDivExpr:
462 6596 : return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S);
463 215747 : case scAddRecExpr:
464 215747 : return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S);
465 4840 : case scSMaxExpr:
466 4840 : return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
467 726 : case scUMaxExpr:
468 726 : return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
469 74862 : case scUnknown:
470 204951 : return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
471 0 : case scCouldNotCompute:
472 0 : return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S);
473 0 : default:
474 0 : llvm_unreachable("Unknown SCEV type!");
475 : }
476 : }
477 49360 :
478 98720 : RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) {
479 0 : llvm_unreachable("Invalid use of SCEVCouldNotCompute!");
480 : }
481 98 : };
482 98 :
483 143 : /// Visit all nodes in the expression tree using worklist traversal.
484 143 : ///
485 271 : /// Visitor implements:
486 271 : /// // return true to follow this node.
487 8679 : /// bool follow(const SCEV *S);
488 8679 : /// // return true to terminate the search.
489 798 : /// bool isDone();
490 798 : template<typename SV>
491 78 : class SCEVTraversal {
492 78 : SV &Visitor;
493 6748 : SmallVector<const SCEV *, 8> Worklist;
494 6748 : SmallPtrSet<const SCEV *, 8> Visited;
495 14 :
496 561225 : void push(const SCEV *S) {
497 561240 : if (Visited.insert(S).second && Visitor.follow(S))
498 471680 : Worklist.push_back(S);
499 561211 : }
500 223824 :
501 207523 : public:
502 169218 : SCEVTraversal(SV& V): Visitor(V) {}
503 207509 :
504 151196 : void visitAll(const SCEV *Root) {
505 151196 : push(Root);
506 174477 : while (!Worklist.empty() && !Visitor.isDone()) {
507 116564 : const SCEV *S = Worklist.pop_back_val();
508 105138 :
509 164918 : switch (S->getSCEVType()) {
510 105268 : case scConstant:
511 105138 : case scUnknown:
512 116688 : break;
513 116688 : case scTruncate:
514 213032 : case scZeroExtend:
515 90178 : case scSignExtend:
516 1588 : push(cast<SCEVCastExpr>(S)->getOperand());
517 207720 : break;
518 143678 : case scAddExpr:
519 0 : case scMulExpr:
520 143910 : case scSMaxExpr:
521 143910 : case scUMaxExpr:
522 482176 : case scAddRecExpr:
523 7318 : for (const auto *Op : cast<SCEVNAryExpr>(S)->operands())
524 6727 : push(Op);
525 678309 : break;
526 0 : case scUDivExpr: {
527 0 : const SCEVUDivExpr *UDiv = cast<SCEVUDivExpr>(S);
528 326 : push(UDiv->getLHS());
529 326 : push(UDiv->getRHS());
530 326 : break;
531 120046 : }
532 93444 : case scCouldNotCompute:
533 12506 : llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
534 0 : default:
535 0 : llvm_unreachable("Unknown SCEV kind!");
536 1319 : }
537 10525 : }
538 54363 : }
539 367988 : };
540 247374 :
541 49 : /// Use SCEVTraversal to visit all nodes in the given expression tree.
542 49 : template<typename SV>
543 88 : void visitAll(const SCEV *Root, SV& Visitor) {
544 1956 : SCEVTraversal<SV> T(Visitor);
545 1886 : T.visitAll(Root);
546 28396 : }
547 12230 :
548 12230 : /// Return true if any node in \p Root satisfies the predicate \p Pred.
549 59308 : template <typename PredTy>
550 328 : bool SCEVExprContains(const SCEV *Root, PredTy Pred) {
551 136 : struct FindClosure {
552 93826 : bool Found = false;
553 1105 : PredTy Pred;
554 145015 :
555 49034 : FindClosure(PredTy Pred) : Pred(Pred) {}
556 49034 :
557 171421 : bool follow(const SCEV *S) {
558 33 : if (!Pred(S))
559 551 : return true;
560 252164 :
561 : Found = true;
562 : return false;
563 0 : }
564 0 :
565 : bool isDone() const { return Found; }
566 55008 : };
567 63166 :
568 46480 : FindClosure FC(Pred);
569 : visitAll(Root, FC);
570 : return FC.Found;
571 451 : }
572 451 :
573 632 : /// This visitor recursively visits a SCEV expression and re-writes it.
574 147740 : /// The result from each visit is cached, so it will return the same
575 99682 : /// SCEV for the same input.
576 112 : template<typename SC>
577 2840 : class SCEVRewriteVisitor : public SCEVVisitor<SC, const SCEV *> {
578 2840 : protected:
579 4815 : ScalarEvolution &SE;
580 4815 : // Memoize the result of each visit so that we only compute once for
581 13456 : // the same input SCEV. This is to avoid redundant computations when
582 14422 : // a SCEV is referenced by multiple SCEVs. Without memoization, this
583 14463 : // visit algorithm would have exponential time complexity in the worst
584 70684 : // case, causing the compiler to hang on certain tests.
585 32 : DenseMap<const SCEV *, const SCEV *> RewriteResults;
586 32 :
587 112455 : public:
588 111087 : SCEVRewriteVisitor(ScalarEvolution &SE) : SE(SE) {}
589 49022 :
590 468273 : const SCEV *visit(const SCEV *S) {
591 466158 : auto It = RewriteResults.find(S);
592 519844 : if (It != RewriteResults.end())
593 45495 : return It->second;
594 398409 : auto* Visited = SCEVVisitor<SC, const SCEV *>::visit(S);
595 505781 : auto Result = RewriteResults.try_emplace(S, Visited);
596 : assert(Result.second && "Should insert a new entry");
597 436390 : return Result.first->second;
598 78414 : }
599 :
600 0 : const SCEV *visitConstant(const SCEVConstant *Constant) {
601 65154 : return Constant;
602 45901 : }
603 2739 :
604 2805 : const SCEV *visitTruncateExpr(const SCEVTruncateExpr *Expr) {
605 2297 : const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
606 3186 : return Operand == Expr->getOperand()
607 2797 : ? Expr
608 4739 : : SE.getTruncateExpr(Operand, Expr->getType());
609 45996 : }
610 31230 :
611 2845 : const SCEV *visitZeroExtendExpr(const SCEVZeroExtendExpr *Expr) {
612 2845 : const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
613 18518 : return Operand == Expr->getOperand()
614 16007 : ? Expr
615 3098 : : SE.getZeroExtendExpr(Operand, Expr->getType());
616 14832 : }
617 62 :
618 1944 : const SCEV *visitSignExtendExpr(const SCEVSignExtendExpr *Expr) {
619 1882 : const SCEV *Operand = ((SC*)this)->visit(Expr->getOperand());
620 6990 : return Operand == Expr->getOperand()
621 26510 : ? Expr
622 28392 : : SE.getSignExtendExpr(Operand, Expr->getType());
623 26510 : }
624 49990 :
625 97370 : const SCEV *visitAddExpr(const SCEVAddExpr *Expr) {
626 51767 : SmallVector<const SCEV *, 2> Operands;
627 179648 : bool Changed = false;
628 252928 : for (auto *Op : Expr->operands()) {
629 111319 : Operands.push_back(((SC*)this)->visit(Op));
630 268835 : Changed |= Op != Operands.back();
631 14511 : }
632 60114 : return !Changed ? Expr : SE.getAddExpr(Operands);
633 936 : }
634 936 :
635 17887 : const SCEV *visitMulExpr(const SCEVMulExpr *Expr) {
636 363 : SmallVector<const SCEV *, 2> Operands;
637 4113 : bool Changed = false;
638 62982 : for (auto *Op : Expr->operands()) {
639 43015 : Operands.push_back(((SC*)this)->visit(Op));
640 43015 : Changed |= Op != Operands.back();
641 12393 : }
642 17782 : return !Changed ? Expr : SE.getMulExpr(Operands);
643 16877 : }
644 157897 :
645 67623 : const SCEV *visitUDivExpr(const SCEVUDivExpr *Expr) {
646 4705 : auto *LHS = ((SC *)this)->visit(Expr->getLHS());
647 4458 : auto *RHS = ((SC *)this)->visit(Expr->getRHS());
648 4444 : bool Changed = LHS != Expr->getLHS() || RHS != Expr->getRHS();
649 320 : return !Changed ? Expr : SE.getUDivExpr(LHS, RHS);
650 6818 : }
651 286 :
652 6558 : const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
653 0 : SmallVector<const SCEV *, 2> Operands;
654 0 : bool Changed = false;
655 31961 : for (auto *Op : Expr->operands()) {
656 25403 : Operands.push_back(((SC*)this)->visit(Op));
657 13428 : Changed |= Op != Operands.back();
658 320 : }
659 39632 : return !Changed ? Expr
660 31952 : : SE.getAddRecExpr(Operands, Expr->getLoop(),
661 38334 : Expr->getNoWrapFlags());
662 115232 : }
663 0 :
664 655 : const SCEV *visitSMaxExpr(const SCEVSMaxExpr *Expr) {
665 166912 : SmallVector<const SCEV *, 2> Operands;
666 0 : bool Changed = false;
667 2031 : for (auto *Op : Expr->operands()) {
668 1376 : Operands.push_back(((SC *)this)->visit(Op));
669 1398 : Changed |= Op != Operands.back();
670 39 : }
671 667 : return !Changed ? Expr : SE.getSMaxExpr(Operands);
672 2832 : }
673 2820 :
674 347 : const SCEV *visitUMaxExpr(const SCEVUMaxExpr *Expr) {
675 0 : SmallVector<const SCEV *, 2> Operands;
676 0 : bool Changed = false;
677 1048 : for (auto *Op : Expr->operands()) {
678 701 : Operands.push_back(((SC*)this)->visit(Op));
679 82571 : Changed |= Op != Operands.back();
680 55274 : }
681 347 : return !Changed ? Expr : SE.getUMaxExpr(Operands);
682 : }
683 0 :
684 178 : const SCEV *visitUnknown(const SCEVUnknown *Expr) {
685 75040 : return Expr;
686 178 : }
687 24011 :
688 48022 : const SCEV *visitCouldNotCompute(const SCEVCouldNotCompute *Expr) {
689 3560 : return Expr;
690 3560 : }
691 0 : };
692 :
693 : using ValueToValueMap = DenseMap<const Value *, Value *>;
694 31776 :
695 : /// The SCEVParameterRewriter takes a scalar evolution expression and updates
696 : /// the SCEVUnknown components following the Map (Value -> Value).
697 1079 : class SCEVParameterRewriter : public SCEVRewriteVisitor<SCEVParameterRewriter> {
698 1079 : public:
699 7486 : static const SCEV *rewrite(const SCEV *Scev, ScalarEvolution &SE,
700 6996 : ValueToValueMap &Map,
701 : bool InterpretConsts = false) {
702 : SCEVParameterRewriter Rewriter(SE, Map, InterpretConsts);
703 10308 : return Rewriter.visit(Scev);
704 9328 : }
705 :
706 : SCEVParameterRewriter(ScalarEvolution &SE, ValueToValueMap &M, bool C)
707 490 : : SCEVRewriteVisitor(SE), Map(M), InterpretConsts(C) {}
708 :
709 32 : const SCEV *visitUnknown(const SCEVUnknown *Expr) {
710 : Value *V = Expr->getValue();
711 32 : if (Map.count(V)) {
712 4 : Value *NV = Map[V];
713 4 : if (InterpretConsts && isa<ConstantInt>(NV))
714 0 : return SE.getConstant(cast<ConstantInt>(NV));
715 4 : return SE.getUnknown(NV);
716 : }
717 28 : return Expr;
718 : }
719 :
720 : private:
721 : ValueToValueMap ⤅
722 : bool InterpretConsts;
723 : };
724 :
725 : using LoopToScevMapT = DenseMap<const Loop *, const SCEV *>;
726 :
727 : /// The SCEVLoopAddRecRewriter takes a scalar evolution expression and applies
728 : /// the Map (Loop -> SCEV) to all AddRecExprs.
729 : class SCEVLoopAddRecRewriter
730 : : public SCEVRewriteVisitor<SCEVLoopAddRecRewriter> {
731 : public:
732 : SCEVLoopAddRecRewriter(ScalarEvolution &SE, LoopToScevMapT &M)
733 2752 : : SCEVRewriteVisitor(SE), Map(M) {}
734 :
735 1376 : static const SCEV *rewrite(const SCEV *Scev, LoopToScevMapT &Map,
736 41059932 : ScalarEvolution &SE) {
737 42685010 : SCEVLoopAddRecRewriter Rewriter(SE, Map);
738 21501378 : return Rewriter.visit(Scev);
739 41059932 : }
740 0 :
741 1328 : const SCEV *visitAddRecExpr(const SCEVAddRecExpr *Expr) {
742 0 : SmallVector<const SCEV *, 2> Operands;
743 3990 : for (const SCEV *Op : Expr->operands())
744 790313 : Operands.push_back(visit(Op));
745 804211 :
746 609322 : const Loop *L = Expr->getLoop();
747 788979 : const SCEV *Res = SE.getAddRecExpr(Operands, L, Expr->getNoWrapFlags());
748 5498 :
749 12321 : if (0 == Map.count(L))
750 5485 : return Res;
751 5498 :
752 113737 : const SCEVAddRecExpr *Rec = cast<SCEVAddRecExpr>(Res);
753 124740 : return Rec->evaluateAtIteration(Map[L], SE);
754 96748 : }
755 113737 :
756 6090246 : private:
757 7496087 : LoopToScevMapT ⤅
758 5014081 : };
759 6090246 :
760 11975 : } // end namespace llvm
761 11975 :
762 9696 : #endif // LLVM_ANALYSIS_SCALAREVOLUTIONEXPRESSIONS_H
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