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DependenceAnalysis.h
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1 //===-- llvm/Analysis/DependenceAnalysis.h -------------------- -*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // DependenceAnalysis is an LLVM pass that analyses dependences between memory
10 // accesses. Currently, it is an implementation of the approach described in
11 //
12 // Practical Dependence Testing
13 // Goff, Kennedy, Tseng
14 // PLDI 1991
15 //
16 // There's a single entry point that analyzes the dependence between a pair
17 // of memory references in a function, returning either NULL, for no dependence,
18 // or a more-or-less detailed description of the dependence between them.
19 //
20 // This pass exists to support the DependenceGraph pass. There are two separate
21 // passes because there's a useful separation of concerns. A dependence exists
22 // if two conditions are met:
23 //
24 // 1) Two instructions reference the same memory location, and
25 // 2) There is a flow of control leading from one instruction to the other.
26 //
27 // DependenceAnalysis attacks the first condition; DependenceGraph will attack
28 // the second (it's not yet ready).
29 //
30 // Please note that this is work in progress and the interface is subject to
31 // change.
32 //
33 // Plausible changes:
34 // Return a set of more precise dependences instead of just one dependence
35 // summarizing all.
36 //
37 //===----------------------------------------------------------------------===//
38 
39 #ifndef LLVM_ANALYSIS_DEPENDENCEANALYSIS_H
40 #define LLVM_ANALYSIS_DEPENDENCEANALYSIS_H
41 
43 #include "llvm/IR/Instructions.h"
44 #include "llvm/IR/PassManager.h"
45 #include "llvm/Pass.h"
46 
47 namespace llvm {
48  class AAResults;
49  template <typename T> class ArrayRef;
50  class Loop;
51  class LoopInfo;
52  class ScalarEvolution;
53  class SCEV;
54  class SCEVConstant;
55  class raw_ostream;
56 
57  /// Dependence - This class represents a dependence between two memory
58  /// memory references in a function. It contains minimal information and
59  /// is used in the very common situation where the compiler is unable to
60  /// determine anything beyond the existence of a dependence; that is, it
61  /// represents a confused dependence (see also FullDependence). In most
62  /// cases (for output, flow, and anti dependences), the dependence implies
63  /// an ordering, where the source must precede the destination; in contrast,
64  /// input dependences are unordered.
65  ///
66  /// When a dependence graph is built, each Dependence will be a member of
67  /// the set of predecessor edges for its destination instruction and a set
68  /// if successor edges for its source instruction. These sets are represented
69  /// as singly-linked lists, with the "next" fields stored in the dependence
70  /// itelf.
71  class Dependence {
72  protected:
73  Dependence(Dependence &&) = default;
74  Dependence &operator=(Dependence &&) = default;
75 
76  public:
78  : Src(Source), Dst(Destination) {}
79  virtual ~Dependence() = default;
80 
81  /// Dependence::DVEntry - Each level in the distance/direction vector
82  /// has a direction (or perhaps a union of several directions), and
83  /// perhaps a distance.
84  struct DVEntry {
85  enum { NONE = 0,
86  LT = 1,
87  EQ = 2,
88  LE = 3,
89  GT = 4,
90  NE = 5,
91  GE = 6,
92  ALL = 7 };
93  unsigned char Direction : 3; // Init to ALL, then refine.
94  bool Scalar : 1; // Init to true.
95  bool PeelFirst : 1; // Peeling the first iteration will break dependence.
96  bool PeelLast : 1; // Peeling the last iteration will break the dependence.
97  bool Splitable : 1; // Splitting the loop will break dependence.
98  const SCEV *Distance = nullptr; // NULL implies no distance available.
101  Splitable(false) {}
102  };
103 
104  /// getSrc - Returns the source instruction for this dependence.
105  ///
106  Instruction *getSrc() const { return Src; }
107 
108  /// getDst - Returns the destination instruction for this dependence.
109  ///
110  Instruction *getDst() const { return Dst; }
111 
112  /// isInput - Returns true if this is an input dependence.
113  ///
114  bool isInput() const;
115 
116  /// isOutput - Returns true if this is an output dependence.
117  ///
118  bool isOutput() const;
119 
120  /// isFlow - Returns true if this is a flow (aka true) dependence.
121  ///
122  bool isFlow() const;
123 
124  /// isAnti - Returns true if this is an anti dependence.
125  ///
126  bool isAnti() const;
127 
128  /// isOrdered - Returns true if dependence is Output, Flow, or Anti
129  ///
130  bool isOrdered() const { return isOutput() || isFlow() || isAnti(); }
131 
132  /// isUnordered - Returns true if dependence is Input
133  ///
134  bool isUnordered() const { return isInput(); }
135 
136  /// isLoopIndependent - Returns true if this is a loop-independent
137  /// dependence.
138  virtual bool isLoopIndependent() const { return true; }
139 
140  /// isConfused - Returns true if this dependence is confused
141  /// (the compiler understands nothing and makes worst-case
142  /// assumptions).
143  virtual bool isConfused() const { return true; }
144 
145  /// isConsistent - Returns true if this dependence is consistent
146  /// (occurs every time the source and destination are executed).
147  virtual bool isConsistent() const { return false; }
148 
149  /// getLevels - Returns the number of common loops surrounding the
150  /// source and destination of the dependence.
151  virtual unsigned getLevels() const { return 0; }
152 
153  /// getDirection - Returns the direction associated with a particular
154  /// level.
155  virtual unsigned getDirection(unsigned Level) const { return DVEntry::ALL; }
156 
157  /// getDistance - Returns the distance (or NULL) associated with a
158  /// particular level.
159  virtual const SCEV *getDistance(unsigned Level) const { return nullptr; }
160 
161  /// Check if the direction vector is negative. A negative direction
162  /// vector means Src and Dst are reversed in the actual program.
163  virtual bool isDirectionNegative() const { return false; }
164 
165  /// If the direction vector is negative, normalize the direction
166  /// vector to make it non-negative. Normalization is done by reversing
167  /// Src and Dst, plus reversing the dependence directions and distances
168  /// in the vector.
169  virtual bool normalize(ScalarEvolution *SE) { return false; }
170 
171  /// isPeelFirst - Returns true if peeling the first iteration from
172  /// this loop will break this dependence.
173  virtual bool isPeelFirst(unsigned Level) const { return false; }
174 
175  /// isPeelLast - Returns true if peeling the last iteration from
176  /// this loop will break this dependence.
177  virtual bool isPeelLast(unsigned Level) const { return false; }
178 
179  /// isSplitable - Returns true if splitting this loop will break
180  /// the dependence.
181  virtual bool isSplitable(unsigned Level) const { return false; }
182 
183  /// isScalar - Returns true if a particular level is scalar; that is,
184  /// if no subscript in the source or destination mention the induction
185  /// variable associated with the loop at this level.
186  virtual bool isScalar(unsigned Level) const;
187 
188  /// getNextPredecessor - Returns the value of the NextPredecessor
189  /// field.
190  const Dependence *getNextPredecessor() const { return NextPredecessor; }
191 
192  /// getNextSuccessor - Returns the value of the NextSuccessor
193  /// field.
194  const Dependence *getNextSuccessor() const { return NextSuccessor; }
195 
196  /// setNextPredecessor - Sets the value of the NextPredecessor
197  /// field.
198  void setNextPredecessor(const Dependence *pred) { NextPredecessor = pred; }
199 
200  /// setNextSuccessor - Sets the value of the NextSuccessor
201  /// field.
202  void setNextSuccessor(const Dependence *succ) { NextSuccessor = succ; }
203 
204  /// dump - For debugging purposes, dumps a dependence to OS.
205  ///
206  void dump(raw_ostream &OS) const;
207 
208  protected:
210 
211  private:
212  const Dependence *NextPredecessor = nullptr, *NextSuccessor = nullptr;
213  friend class DependenceInfo;
214  };
215 
216  /// FullDependence - This class represents a dependence between two memory
217  /// references in a function. It contains detailed information about the
218  /// dependence (direction vectors, etc.) and is used when the compiler is
219  /// able to accurately analyze the interaction of the references; that is,
220  /// it is not a confused dependence (see Dependence). In most cases
221  /// (for output, flow, and anti dependences), the dependence implies an
222  /// ordering, where the source must precede the destination; in contrast,
223  /// input dependences are unordered.
224  class FullDependence final : public Dependence {
225  public:
226  FullDependence(Instruction *Src, Instruction *Dst, bool LoopIndependent,
227  unsigned Levels);
228 
229  /// isLoopIndependent - Returns true if this is a loop-independent
230  /// dependence.
231  bool isLoopIndependent() const override { return LoopIndependent; }
232 
233  /// isConfused - Returns true if this dependence is confused
234  /// (the compiler understands nothing and makes worst-case
235  /// assumptions).
236  bool isConfused() const override { return false; }
237 
238  /// isConsistent - Returns true if this dependence is consistent
239  /// (occurs every time the source and destination are executed).
240  bool isConsistent() const override { return Consistent; }
241 
242  /// getLevels - Returns the number of common loops surrounding the
243  /// source and destination of the dependence.
244  unsigned getLevels() const override { return Levels; }
245 
246  /// getDirection - Returns the direction associated with a particular
247  /// level.
248  unsigned getDirection(unsigned Level) const override;
249 
250  /// getDistance - Returns the distance (or NULL) associated with a
251  /// particular level.
252  const SCEV *getDistance(unsigned Level) const override;
253 
254  /// Check if the direction vector is negative. A negative direction
255  /// vector means Src and Dst are reversed in the actual program.
256  bool isDirectionNegative() const override;
257 
258  /// If the direction vector is negative, normalize the direction
259  /// vector to make it non-negative. Normalization is done by reversing
260  /// Src and Dst, plus reversing the dependence directions and distances
261  /// in the vector.
262  bool normalize(ScalarEvolution *SE) override;
263 
264  /// isPeelFirst - Returns true if peeling the first iteration from
265  /// this loop will break this dependence.
266  bool isPeelFirst(unsigned Level) const override;
267 
268  /// isPeelLast - Returns true if peeling the last iteration from
269  /// this loop will break this dependence.
270  bool isPeelLast(unsigned Level) const override;
271 
272  /// isSplitable - Returns true if splitting the loop will break
273  /// the dependence.
274  bool isSplitable(unsigned Level) const override;
275 
276  /// isScalar - Returns true if a particular level is scalar; that is,
277  /// if no subscript in the source or destination mention the induction
278  /// variable associated with the loop at this level.
279  bool isScalar(unsigned Level) const override;
280 
281  private:
282  unsigned short Levels;
283  bool LoopIndependent;
284  bool Consistent; // Init to true, then refine.
285  std::unique_ptr<DVEntry[]> DV;
286  friend class DependenceInfo;
287  };
288 
289  /// DependenceInfo - This class is the main dependence-analysis driver.
290  ///
292  public:
294  LoopInfo *LI)
295  : AA(AA), SE(SE), LI(LI), F(F) {}
296 
297  /// Handle transitive invalidation when the cached analysis results go away.
298  bool invalidate(Function &F, const PreservedAnalyses &PA,
300 
301  /// depends - Tests for a dependence between the Src and Dst instructions.
302  /// Returns NULL if no dependence; otherwise, returns a Dependence (or a
303  /// FullDependence) with as much information as can be gleaned.
304  /// The flag PossiblyLoopIndependent should be set by the caller
305  /// if it appears that control flow can reach from Src to Dst
306  /// without traversing a loop back edge.
307  std::unique_ptr<Dependence> depends(Instruction *Src,
308  Instruction *Dst,
309  bool PossiblyLoopIndependent);
310 
311  /// getSplitIteration - Give a dependence that's splittable at some
312  /// particular level, return the iteration that should be used to split
313  /// the loop.
314  ///
315  /// Generally, the dependence analyzer will be used to build
316  /// a dependence graph for a function (basically a map from instructions
317  /// to dependences). Looking for cycles in the graph shows us loops
318  /// that cannot be trivially vectorized/parallelized.
319  ///
320  /// We can try to improve the situation by examining all the dependences
321  /// that make up the cycle, looking for ones we can break.
322  /// Sometimes, peeling the first or last iteration of a loop will break
323  /// dependences, and there are flags for those possibilities.
324  /// Sometimes, splitting a loop at some other iteration will do the trick,
325  /// and we've got a flag for that case. Rather than waste the space to
326  /// record the exact iteration (since we rarely know), we provide
327  /// a method that calculates the iteration. It's a drag that it must work
328  /// from scratch, but wonderful in that it's possible.
329  ///
330  /// Here's an example:
331  ///
332  /// for (i = 0; i < 10; i++)
333  /// A[i] = ...
334  /// ... = A[11 - i]
335  ///
336  /// There's a loop-carried flow dependence from the store to the load,
337  /// found by the weak-crossing SIV test. The dependence will have a flag,
338  /// indicating that the dependence can be broken by splitting the loop.
339  /// Calling getSplitIteration will return 5.
340  /// Splitting the loop breaks the dependence, like so:
341  ///
342  /// for (i = 0; i <= 5; i++)
343  /// A[i] = ...
344  /// ... = A[11 - i]
345  /// for (i = 6; i < 10; i++)
346  /// A[i] = ...
347  /// ... = A[11 - i]
348  ///
349  /// breaks the dependence and allows us to vectorize/parallelize
350  /// both loops.
351  const SCEV *getSplitIteration(const Dependence &Dep, unsigned Level);
352 
353  Function *getFunction() const { return F; }
354 
355  private:
356  AAResults *AA;
357  ScalarEvolution *SE;
358  LoopInfo *LI;
359  Function *F;
360 
361  /// Subscript - This private struct represents a pair of subscripts from
362  /// a pair of potentially multi-dimensional array references. We use a
363  /// vector of them to guide subscript partitioning.
364  struct Subscript {
365  const SCEV *Src;
366  const SCEV *Dst;
367  enum ClassificationKind { ZIV, SIV, RDIV, MIV, NonLinear } Classification;
368  SmallBitVector Loops;
369  SmallBitVector GroupLoops;
370  SmallBitVector Group;
371  };
372 
373  struct CoefficientInfo {
374  const SCEV *Coeff;
375  const SCEV *PosPart;
376  const SCEV *NegPart;
377  const SCEV *Iterations;
378  };
379 
380  struct BoundInfo {
381  const SCEV *Iterations;
382  const SCEV *Upper[8];
383  const SCEV *Lower[8];
384  unsigned char Direction;
385  unsigned char DirSet;
386  };
387 
388  /// Constraint - This private class represents a constraint, as defined
389  /// in the paper
390  ///
391  /// Practical Dependence Testing
392  /// Goff, Kennedy, Tseng
393  /// PLDI 1991
394  ///
395  /// There are 5 kinds of constraint, in a hierarchy.
396  /// 1) Any - indicates no constraint, any dependence is possible.
397  /// 2) Line - A line ax + by = c, where a, b, and c are parameters,
398  /// representing the dependence equation.
399  /// 3) Distance - The value d of the dependence distance;
400  /// 4) Point - A point <x, y> representing the dependence from
401  /// iteration x to iteration y.
402  /// 5) Empty - No dependence is possible.
403  class Constraint {
404  private:
405  enum ConstraintKind { Empty, Point, Distance, Line, Any } Kind;
406  ScalarEvolution *SE;
407  const SCEV *A;
408  const SCEV *B;
409  const SCEV *C;
410  const Loop *AssociatedLoop;
411 
412  public:
413  /// isEmpty - Return true if the constraint is of kind Empty.
414  bool isEmpty() const { return Kind == Empty; }
415 
416  /// isPoint - Return true if the constraint is of kind Point.
417  bool isPoint() const { return Kind == Point; }
418 
419  /// isDistance - Return true if the constraint is of kind Distance.
420  bool isDistance() const { return Kind == Distance; }
421 
422  /// isLine - Return true if the constraint is of kind Line.
423  /// Since Distance's can also be represented as Lines, we also return
424  /// true if the constraint is of kind Distance.
425  bool isLine() const { return Kind == Line || Kind == Distance; }
426 
427  /// isAny - Return true if the constraint is of kind Any;
428  bool isAny() const { return Kind == Any; }
429 
430  /// getX - If constraint is a point <X, Y>, returns X.
431  /// Otherwise assert.
432  const SCEV *getX() const;
433 
434  /// getY - If constraint is a point <X, Y>, returns Y.
435  /// Otherwise assert.
436  const SCEV *getY() const;
437 
438  /// getA - If constraint is a line AX + BY = C, returns A.
439  /// Otherwise assert.
440  const SCEV *getA() const;
441 
442  /// getB - If constraint is a line AX + BY = C, returns B.
443  /// Otherwise assert.
444  const SCEV *getB() const;
445 
446  /// getC - If constraint is a line AX + BY = C, returns C.
447  /// Otherwise assert.
448  const SCEV *getC() const;
449 
450  /// getD - If constraint is a distance, returns D.
451  /// Otherwise assert.
452  const SCEV *getD() const;
453 
454  /// getAssociatedLoop - Returns the loop associated with this constraint.
455  const Loop *getAssociatedLoop() const;
456 
457  /// setPoint - Change a constraint to Point.
458  void setPoint(const SCEV *X, const SCEV *Y, const Loop *CurrentLoop);
459 
460  /// setLine - Change a constraint to Line.
461  void setLine(const SCEV *A, const SCEV *B,
462  const SCEV *C, const Loop *CurrentLoop);
463 
464  /// setDistance - Change a constraint to Distance.
465  void setDistance(const SCEV *D, const Loop *CurrentLoop);
466 
467  /// setEmpty - Change a constraint to Empty.
468  void setEmpty();
469 
470  /// setAny - Change a constraint to Any.
471  void setAny(ScalarEvolution *SE);
472 
473  /// dump - For debugging purposes. Dumps the constraint
474  /// out to OS.
475  void dump(raw_ostream &OS) const;
476  };
477 
478  /// establishNestingLevels - Examines the loop nesting of the Src and Dst
479  /// instructions and establishes their shared loops. Sets the variables
480  /// CommonLevels, SrcLevels, and MaxLevels.
481  /// The source and destination instructions needn't be contained in the same
482  /// loop. The routine establishNestingLevels finds the level of most deeply
483  /// nested loop that contains them both, CommonLevels. An instruction that's
484  /// not contained in a loop is at level = 0. MaxLevels is equal to the level
485  /// of the source plus the level of the destination, minus CommonLevels.
486  /// This lets us allocate vectors MaxLevels in length, with room for every
487  /// distinct loop referenced in both the source and destination subscripts.
488  /// The variable SrcLevels is the nesting depth of the source instruction.
489  /// It's used to help calculate distinct loops referenced by the destination.
490  /// Here's the map from loops to levels:
491  /// 0 - unused
492  /// 1 - outermost common loop
493  /// ... - other common loops
494  /// CommonLevels - innermost common loop
495  /// ... - loops containing Src but not Dst
496  /// SrcLevels - innermost loop containing Src but not Dst
497  /// ... - loops containing Dst but not Src
498  /// MaxLevels - innermost loop containing Dst but not Src
499  /// Consider the follow code fragment:
500  /// for (a = ...) {
501  /// for (b = ...) {
502  /// for (c = ...) {
503  /// for (d = ...) {
504  /// A[] = ...;
505  /// }
506  /// }
507  /// for (e = ...) {
508  /// for (f = ...) {
509  /// for (g = ...) {
510  /// ... = A[];
511  /// }
512  /// }
513  /// }
514  /// }
515  /// }
516  /// If we're looking at the possibility of a dependence between the store
517  /// to A (the Src) and the load from A (the Dst), we'll note that they
518  /// have 2 loops in common, so CommonLevels will equal 2 and the direction
519  /// vector for Result will have 2 entries. SrcLevels = 4 and MaxLevels = 7.
520  /// A map from loop names to level indices would look like
521  /// a - 1
522  /// b - 2 = CommonLevels
523  /// c - 3
524  /// d - 4 = SrcLevels
525  /// e - 5
526  /// f - 6
527  /// g - 7 = MaxLevels
528  void establishNestingLevels(const Instruction *Src,
529  const Instruction *Dst);
530 
531  unsigned CommonLevels, SrcLevels, MaxLevels;
532 
533  /// mapSrcLoop - Given one of the loops containing the source, return
534  /// its level index in our numbering scheme.
535  unsigned mapSrcLoop(const Loop *SrcLoop) const;
536 
537  /// mapDstLoop - Given one of the loops containing the destination,
538  /// return its level index in our numbering scheme.
539  unsigned mapDstLoop(const Loop *DstLoop) const;
540 
541  /// isLoopInvariant - Returns true if Expression is loop invariant
542  /// in LoopNest.
543  bool isLoopInvariant(const SCEV *Expression, const Loop *LoopNest) const;
544 
545  /// Makes sure all subscript pairs share the same integer type by
546  /// sign-extending as necessary.
547  /// Sign-extending a subscript is safe because getelementptr assumes the
548  /// array subscripts are signed.
549  void unifySubscriptType(ArrayRef<Subscript *> Pairs);
550 
551  /// removeMatchingExtensions - Examines a subscript pair.
552  /// If the source and destination are identically sign (or zero)
553  /// extended, it strips off the extension in an effort to
554  /// simplify the actual analysis.
555  void removeMatchingExtensions(Subscript *Pair);
556 
557  /// collectCommonLoops - Finds the set of loops from the LoopNest that
558  /// have a level <= CommonLevels and are referred to by the SCEV Expression.
559  void collectCommonLoops(const SCEV *Expression,
560  const Loop *LoopNest,
561  SmallBitVector &Loops) const;
562 
563  /// checkSrcSubscript - Examines the SCEV Src, returning true iff it's
564  /// linear. Collect the set of loops mentioned by Src.
565  bool checkSrcSubscript(const SCEV *Src,
566  const Loop *LoopNest,
567  SmallBitVector &Loops);
568 
569  /// checkDstSubscript - Examines the SCEV Dst, returning true iff it's
570  /// linear. Collect the set of loops mentioned by Dst.
571  bool checkDstSubscript(const SCEV *Dst,
572  const Loop *LoopNest,
573  SmallBitVector &Loops);
574 
575  /// isKnownPredicate - Compare X and Y using the predicate Pred.
576  /// Basically a wrapper for SCEV::isKnownPredicate,
577  /// but tries harder, especially in the presence of sign and zero
578  /// extensions and symbolics.
579  bool isKnownPredicate(ICmpInst::Predicate Pred,
580  const SCEV *X,
581  const SCEV *Y) const;
582 
583  /// isKnownLessThan - Compare to see if S is less than Size
584  /// Another wrapper for isKnownNegative(S - max(Size, 1)) with some extra
585  /// checking if S is an AddRec and we can prove lessthan using the loop
586  /// bounds.
587  bool isKnownLessThan(const SCEV *S, const SCEV *Size) const;
588 
589  /// isKnownNonNegative - Compare to see if S is known not to be negative
590  /// Uses the fact that S comes from Ptr, which may be an inbound GEP,
591  /// Proving there is no wrapping going on.
592  bool isKnownNonNegative(const SCEV *S, const Value *Ptr) const;
593 
594  /// collectUpperBound - All subscripts are the same type (on my machine,
595  /// an i64). The loop bound may be a smaller type. collectUpperBound
596  /// find the bound, if available, and zero extends it to the Type T.
597  /// (I zero extend since the bound should always be >= 0.)
598  /// If no upper bound is available, return NULL.
599  const SCEV *collectUpperBound(const Loop *l, Type *T) const;
600 
601  /// collectConstantUpperBound - Calls collectUpperBound(), then
602  /// attempts to cast it to SCEVConstant. If the cast fails,
603  /// returns NULL.
604  const SCEVConstant *collectConstantUpperBound(const Loop *l, Type *T) const;
605 
606  /// classifyPair - Examines the subscript pair (the Src and Dst SCEVs)
607  /// and classifies it as either ZIV, SIV, RDIV, MIV, or Nonlinear.
608  /// Collects the associated loops in a set.
609  Subscript::ClassificationKind classifyPair(const SCEV *Src,
610  const Loop *SrcLoopNest,
611  const SCEV *Dst,
612  const Loop *DstLoopNest,
613  SmallBitVector &Loops);
614 
615  /// testZIV - Tests the ZIV subscript pair (Src and Dst) for dependence.
616  /// Returns true if any possible dependence is disproved.
617  /// If there might be a dependence, returns false.
618  /// If the dependence isn't proven to exist,
619  /// marks the Result as inconsistent.
620  bool testZIV(const SCEV *Src,
621  const SCEV *Dst,
622  FullDependence &Result) const;
623 
624  /// testSIV - Tests the SIV subscript pair (Src and Dst) for dependence.
625  /// Things of the form [c1 + a1*i] and [c2 + a2*j], where
626  /// i and j are induction variables, c1 and c2 are loop invariant,
627  /// and a1 and a2 are constant.
628  /// Returns true if any possible dependence is disproved.
629  /// If there might be a dependence, returns false.
630  /// Sets appropriate direction vector entry and, when possible,
631  /// the distance vector entry.
632  /// If the dependence isn't proven to exist,
633  /// marks the Result as inconsistent.
634  bool testSIV(const SCEV *Src,
635  const SCEV *Dst,
636  unsigned &Level,
637  FullDependence &Result,
638  Constraint &NewConstraint,
639  const SCEV *&SplitIter) const;
640 
641  /// testRDIV - Tests the RDIV subscript pair (Src and Dst) for dependence.
642  /// Things of the form [c1 + a1*i] and [c2 + a2*j]
643  /// where i and j are induction variables, c1 and c2 are loop invariant,
644  /// and a1 and a2 are constant.
645  /// With minor algebra, this test can also be used for things like
646  /// [c1 + a1*i + a2*j][c2].
647  /// Returns true if any possible dependence is disproved.
648  /// If there might be a dependence, returns false.
649  /// Marks the Result as inconsistent.
650  bool testRDIV(const SCEV *Src,
651  const SCEV *Dst,
652  FullDependence &Result) const;
653 
654  /// testMIV - Tests the MIV subscript pair (Src and Dst) for dependence.
655  /// Returns true if dependence disproved.
656  /// Can sometimes refine direction vectors.
657  bool testMIV(const SCEV *Src,
658  const SCEV *Dst,
659  const SmallBitVector &Loops,
660  FullDependence &Result) const;
661 
662  /// strongSIVtest - Tests the strong SIV subscript pair (Src and Dst)
663  /// for dependence.
664  /// Things of the form [c1 + a*i] and [c2 + a*i],
665  /// where i is an induction variable, c1 and c2 are loop invariant,
666  /// and a is a constant
667  /// Returns true if any possible dependence is disproved.
668  /// If there might be a dependence, returns false.
669  /// Sets appropriate direction and distance.
670  bool strongSIVtest(const SCEV *Coeff,
671  const SCEV *SrcConst,
672  const SCEV *DstConst,
673  const Loop *CurrentLoop,
674  unsigned Level,
675  FullDependence &Result,
676  Constraint &NewConstraint) const;
677 
678  /// weakCrossingSIVtest - Tests the weak-crossing SIV subscript pair
679  /// (Src and Dst) for dependence.
680  /// Things of the form [c1 + a*i] and [c2 - a*i],
681  /// where i is an induction variable, c1 and c2 are loop invariant,
682  /// and a is a constant.
683  /// Returns true if any possible dependence is disproved.
684  /// If there might be a dependence, returns false.
685  /// Sets appropriate direction entry.
686  /// Set consistent to false.
687  /// Marks the dependence as splitable.
688  bool weakCrossingSIVtest(const SCEV *SrcCoeff,
689  const SCEV *SrcConst,
690  const SCEV *DstConst,
691  const Loop *CurrentLoop,
692  unsigned Level,
693  FullDependence &Result,
694  Constraint &NewConstraint,
695  const SCEV *&SplitIter) const;
696 
697  /// ExactSIVtest - Tests the SIV subscript pair
698  /// (Src and Dst) for dependence.
699  /// Things of the form [c1 + a1*i] and [c2 + a2*i],
700  /// where i is an induction variable, c1 and c2 are loop invariant,
701  /// and a1 and a2 are constant.
702  /// Returns true if any possible dependence is disproved.
703  /// If there might be a dependence, returns false.
704  /// Sets appropriate direction entry.
705  /// Set consistent to false.
706  bool exactSIVtest(const SCEV *SrcCoeff,
707  const SCEV *DstCoeff,
708  const SCEV *SrcConst,
709  const SCEV *DstConst,
710  const Loop *CurrentLoop,
711  unsigned Level,
712  FullDependence &Result,
713  Constraint &NewConstraint) const;
714 
715  /// weakZeroSrcSIVtest - Tests the weak-zero SIV subscript pair
716  /// (Src and Dst) for dependence.
717  /// Things of the form [c1] and [c2 + a*i],
718  /// where i is an induction variable, c1 and c2 are loop invariant,
719  /// and a is a constant. See also weakZeroDstSIVtest.
720  /// Returns true if any possible dependence is disproved.
721  /// If there might be a dependence, returns false.
722  /// Sets appropriate direction entry.
723  /// Set consistent to false.
724  /// If loop peeling will break the dependence, mark appropriately.
725  bool weakZeroSrcSIVtest(const SCEV *DstCoeff,
726  const SCEV *SrcConst,
727  const SCEV *DstConst,
728  const Loop *CurrentLoop,
729  unsigned Level,
730  FullDependence &Result,
731  Constraint &NewConstraint) const;
732 
733  /// weakZeroDstSIVtest - Tests the weak-zero SIV subscript pair
734  /// (Src and Dst) for dependence.
735  /// Things of the form [c1 + a*i] and [c2],
736  /// where i is an induction variable, c1 and c2 are loop invariant,
737  /// and a is a constant. See also weakZeroSrcSIVtest.
738  /// Returns true if any possible dependence is disproved.
739  /// If there might be a dependence, returns false.
740  /// Sets appropriate direction entry.
741  /// Set consistent to false.
742  /// If loop peeling will break the dependence, mark appropriately.
743  bool weakZeroDstSIVtest(const SCEV *SrcCoeff,
744  const SCEV *SrcConst,
745  const SCEV *DstConst,
746  const Loop *CurrentLoop,
747  unsigned Level,
748  FullDependence &Result,
749  Constraint &NewConstraint) const;
750 
751  /// exactRDIVtest - Tests the RDIV subscript pair for dependence.
752  /// Things of the form [c1 + a*i] and [c2 + b*j],
753  /// where i and j are induction variable, c1 and c2 are loop invariant,
754  /// and a and b are constants.
755  /// Returns true if any possible dependence is disproved.
756  /// Marks the result as inconsistent.
757  /// Works in some cases that symbolicRDIVtest doesn't,
758  /// and vice versa.
759  bool exactRDIVtest(const SCEV *SrcCoeff,
760  const SCEV *DstCoeff,
761  const SCEV *SrcConst,
762  const SCEV *DstConst,
763  const Loop *SrcLoop,
764  const Loop *DstLoop,
765  FullDependence &Result) const;
766 
767  /// symbolicRDIVtest - Tests the RDIV subscript pair for dependence.
768  /// Things of the form [c1 + a*i] and [c2 + b*j],
769  /// where i and j are induction variable, c1 and c2 are loop invariant,
770  /// and a and b are constants.
771  /// Returns true if any possible dependence is disproved.
772  /// Marks the result as inconsistent.
773  /// Works in some cases that exactRDIVtest doesn't,
774  /// and vice versa. Can also be used as a backup for
775  /// ordinary SIV tests.
776  bool symbolicRDIVtest(const SCEV *SrcCoeff,
777  const SCEV *DstCoeff,
778  const SCEV *SrcConst,
779  const SCEV *DstConst,
780  const Loop *SrcLoop,
781  const Loop *DstLoop) const;
782 
783  /// gcdMIVtest - Tests an MIV subscript pair for dependence.
784  /// Returns true if any possible dependence is disproved.
785  /// Marks the result as inconsistent.
786  /// Can sometimes disprove the equal direction for 1 or more loops.
787  // Can handle some symbolics that even the SIV tests don't get,
788  /// so we use it as a backup for everything.
789  bool gcdMIVtest(const SCEV *Src,
790  const SCEV *Dst,
791  FullDependence &Result) const;
792 
793  /// banerjeeMIVtest - Tests an MIV subscript pair for dependence.
794  /// Returns true if any possible dependence is disproved.
795  /// Marks the result as inconsistent.
796  /// Computes directions.
797  bool banerjeeMIVtest(const SCEV *Src,
798  const SCEV *Dst,
799  const SmallBitVector &Loops,
800  FullDependence &Result) const;
801 
802  /// collectCoefficientInfo - Walks through the subscript,
803  /// collecting each coefficient, the associated loop bounds,
804  /// and recording its positive and negative parts for later use.
805  CoefficientInfo *collectCoeffInfo(const SCEV *Subscript,
806  bool SrcFlag,
807  const SCEV *&Constant) const;
808 
809  /// getPositivePart - X^+ = max(X, 0).
810  ///
811  const SCEV *getPositivePart(const SCEV *X) const;
812 
813  /// getNegativePart - X^- = min(X, 0).
814  ///
815  const SCEV *getNegativePart(const SCEV *X) const;
816 
817  /// getLowerBound - Looks through all the bounds info and
818  /// computes the lower bound given the current direction settings
819  /// at each level.
820  const SCEV *getLowerBound(BoundInfo *Bound) const;
821 
822  /// getUpperBound - Looks through all the bounds info and
823  /// computes the upper bound given the current direction settings
824  /// at each level.
825  const SCEV *getUpperBound(BoundInfo *Bound) const;
826 
827  /// exploreDirections - Hierarchically expands the direction vector
828  /// search space, combining the directions of discovered dependences
829  /// in the DirSet field of Bound. Returns the number of distinct
830  /// dependences discovered. If the dependence is disproved,
831  /// it will return 0.
832  unsigned exploreDirections(unsigned Level,
833  CoefficientInfo *A,
834  CoefficientInfo *B,
835  BoundInfo *Bound,
836  const SmallBitVector &Loops,
837  unsigned &DepthExpanded,
838  const SCEV *Delta) const;
839 
840  /// testBounds - Returns true iff the current bounds are plausible.
841  bool testBounds(unsigned char DirKind,
842  unsigned Level,
843  BoundInfo *Bound,
844  const SCEV *Delta) const;
845 
846  /// findBoundsALL - Computes the upper and lower bounds for level K
847  /// using the * direction. Records them in Bound.
848  void findBoundsALL(CoefficientInfo *A,
849  CoefficientInfo *B,
850  BoundInfo *Bound,
851  unsigned K) const;
852 
853  /// findBoundsLT - Computes the upper and lower bounds for level K
854  /// using the < direction. Records them in Bound.
855  void findBoundsLT(CoefficientInfo *A,
856  CoefficientInfo *B,
857  BoundInfo *Bound,
858  unsigned K) const;
859 
860  /// findBoundsGT - Computes the upper and lower bounds for level K
861  /// using the > direction. Records them in Bound.
862  void findBoundsGT(CoefficientInfo *A,
863  CoefficientInfo *B,
864  BoundInfo *Bound,
865  unsigned K) const;
866 
867  /// findBoundsEQ - Computes the upper and lower bounds for level K
868  /// using the = direction. Records them in Bound.
869  void findBoundsEQ(CoefficientInfo *A,
870  CoefficientInfo *B,
871  BoundInfo *Bound,
872  unsigned K) const;
873 
874  /// intersectConstraints - Updates X with the intersection
875  /// of the Constraints X and Y. Returns true if X has changed.
876  bool intersectConstraints(Constraint *X,
877  const Constraint *Y);
878 
879  /// propagate - Review the constraints, looking for opportunities
880  /// to simplify a subscript pair (Src and Dst).
881  /// Return true if some simplification occurs.
882  /// If the simplification isn't exact (that is, if it is conservative
883  /// in terms of dependence), set consistent to false.
884  bool propagate(const SCEV *&Src,
885  const SCEV *&Dst,
886  SmallBitVector &Loops,
887  SmallVectorImpl<Constraint> &Constraints,
888  bool &Consistent);
889 
890  /// propagateDistance - Attempt to propagate a distance
891  /// constraint into a subscript pair (Src and Dst).
892  /// Return true if some simplification occurs.
893  /// If the simplification isn't exact (that is, if it is conservative
894  /// in terms of dependence), set consistent to false.
895  bool propagateDistance(const SCEV *&Src,
896  const SCEV *&Dst,
897  Constraint &CurConstraint,
898  bool &Consistent);
899 
900  /// propagatePoint - Attempt to propagate a point
901  /// constraint into a subscript pair (Src and Dst).
902  /// Return true if some simplification occurs.
903  bool propagatePoint(const SCEV *&Src,
904  const SCEV *&Dst,
905  Constraint &CurConstraint);
906 
907  /// propagateLine - Attempt to propagate a line
908  /// constraint into a subscript pair (Src and Dst).
909  /// Return true if some simplification occurs.
910  /// If the simplification isn't exact (that is, if it is conservative
911  /// in terms of dependence), set consistent to false.
912  bool propagateLine(const SCEV *&Src,
913  const SCEV *&Dst,
914  Constraint &CurConstraint,
915  bool &Consistent);
916 
917  /// findCoefficient - Given a linear SCEV,
918  /// return the coefficient corresponding to specified loop.
919  /// If there isn't one, return the SCEV constant 0.
920  /// For example, given a*i + b*j + c*k, returning the coefficient
921  /// corresponding to the j loop would yield b.
922  const SCEV *findCoefficient(const SCEV *Expr,
923  const Loop *TargetLoop) const;
924 
925  /// zeroCoefficient - Given a linear SCEV,
926  /// return the SCEV given by zeroing out the coefficient
927  /// corresponding to the specified loop.
928  /// For example, given a*i + b*j + c*k, zeroing the coefficient
929  /// corresponding to the j loop would yield a*i + c*k.
930  const SCEV *zeroCoefficient(const SCEV *Expr,
931  const Loop *TargetLoop) const;
932 
933  /// addToCoefficient - Given a linear SCEV Expr,
934  /// return the SCEV given by adding some Value to the
935  /// coefficient corresponding to the specified TargetLoop.
936  /// For example, given a*i + b*j + c*k, adding 1 to the coefficient
937  /// corresponding to the j loop would yield a*i + (b+1)*j + c*k.
938  const SCEV *addToCoefficient(const SCEV *Expr,
939  const Loop *TargetLoop,
940  const SCEV *Value) const;
941 
942  /// updateDirection - Update direction vector entry
943  /// based on the current constraint.
944  void updateDirection(Dependence::DVEntry &Level,
945  const Constraint &CurConstraint) const;
946 
947  /// Given a linear access function, tries to recover subscripts
948  /// for each dimension of the array element access.
949  bool tryDelinearize(Instruction *Src, Instruction *Dst,
950  SmallVectorImpl<Subscript> &Pair);
951 
952  /// Tries to delinearize \p Src and \p Dst access functions for a fixed size
953  /// multi-dimensional array. Calls tryDelinearizeFixedSizeImpl() to
954  /// delinearize \p Src and \p Dst separately,
955  bool tryDelinearizeFixedSize(Instruction *Src, Instruction *Dst,
956  const SCEV *SrcAccessFn,
957  const SCEV *DstAccessFn,
958  SmallVectorImpl<const SCEV *> &SrcSubscripts,
959  SmallVectorImpl<const SCEV *> &DstSubscripts);
960 
961  /// Tries to delinearize access function for a multi-dimensional array with
962  /// symbolic runtime sizes.
963  /// Returns true upon success and false otherwise.
964  bool tryDelinearizeParametricSize(
965  Instruction *Src, Instruction *Dst, const SCEV *SrcAccessFn,
966  const SCEV *DstAccessFn, SmallVectorImpl<const SCEV *> &SrcSubscripts,
967  SmallVectorImpl<const SCEV *> &DstSubscripts);
968 
969  /// checkSubscript - Helper function for checkSrcSubscript and
970  /// checkDstSubscript to avoid duplicate code
971  bool checkSubscript(const SCEV *Expr, const Loop *LoopNest,
972  SmallBitVector &Loops, bool IsSrc);
973  }; // class DependenceInfo
974 
975  /// AnalysisPass to compute dependence information in a function
976  class DependenceAnalysis : public AnalysisInfoMixin<DependenceAnalysis> {
977  public:
980 
981  private:
982  static AnalysisKey Key;
984  }; // class DependenceAnalysis
985 
986  /// Printer pass to dump DA results.
988  : public PassInfoMixin<DependenceAnalysisPrinterPass> {
990  bool NormalizeResults = false)
991  : OS(OS), NormalizeResults(NormalizeResults) {}
992 
994 
995  private:
996  raw_ostream &OS;
997  bool NormalizeResults;
998  }; // class DependenceAnalysisPrinterPass
999 
1000  /// Legacy pass manager pass to access dependence information
1002  public:
1003  static char ID; // Class identification, replacement for typeinfo
1005 
1006  bool runOnFunction(Function &F) override;
1007  void releaseMemory() override;
1008  void getAnalysisUsage(AnalysisUsage &) const override;
1009  void print(raw_ostream &, const Module * = nullptr) const override;
1010  DependenceInfo &getDI() const;
1011 
1012  private:
1013  std::unique_ptr<DependenceInfo> info;
1014  }; // class DependenceAnalysisWrapperPass
1015 
1016  /// createDependenceAnalysisPass - This creates an instance of the
1017  /// DependenceAnalysis wrapper pass.
1019 
1020 } // namespace llvm
1021 
1022 #endif
llvm::PreservedAnalyses
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:152
llvm::Dependence::isSplitable
virtual bool isSplitable(unsigned Level) const
isSplitable - Returns true if splitting this loop will break the dependence.
Definition: DependenceAnalysis.h:181
llvm::FullDependence::isConfused
bool isConfused() const override
isConfused - Returns true if this dependence is confused (the compiler understands nothing and makes ...
Definition: DependenceAnalysis.h:236
llvm
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
llvm::Dependence::~Dependence
virtual ~Dependence()=default
llvm::Dependence::isFlow
bool isFlow() const
isFlow - Returns true if this is a flow (aka true) dependence.
Definition: DependenceAnalysis.cpp:242
llvm::HexPrintStyle::Upper
@ Upper
llvm::FullDependence::isConsistent
bool isConsistent() const override
isConsistent - Returns true if this dependence is consistent (occurs every time the source and destin...
Definition: DependenceAnalysis.h:240
llvm::DependenceAnalysisWrapperPass::getAnalysisUsage
void getAnalysisUsage(AnalysisUsage &) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
Definition: DependenceAnalysis.cpp:168
llvm::CmpInst::Predicate
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:719
llvm::Dependence::DVEntry::LE
@ LE
Definition: DependenceAnalysis.h:88
llvm::PassInfoMixin
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:371
llvm::DependenceAnalysisWrapperPass
Legacy pass manager pass to access dependence information.
Definition: DependenceAnalysis.h:1001
llvm::Function
Definition: Function.h:60
Pass.h
Loops
Hexagon Hardware Loops
Definition: HexagonHardwareLoops.cpp:374
llvm::Dependence::DVEntry::GE
@ GE
Definition: DependenceAnalysis.h:91
llvm::Dependence::getLevels
virtual unsigned getLevels() const
getLevels - Returns the number of common loops surrounding the source and destination of the dependen...
Definition: DependenceAnalysis.h:151
llvm::Dependence::dump
void dump(raw_ostream &OS) const
dump - For debugging purposes, dumps a dependence to OS.
Definition: DependenceAnalysis.cpp:656
llvm::FullDependence::isSplitable
bool isSplitable(unsigned Level) const override
isSplitable - Returns true if splitting the loop will break the dependence.
Definition: DependenceAnalysis.cpp:373
llvm::DependenceInfo::getFunction
Function * getFunction() const
Definition: DependenceAnalysis.h:353
llvm::DependenceInfo::DependenceInfo
DependenceInfo(Function *F, AAResults *AA, ScalarEvolution *SE, LoopInfo *LI)
Definition: DependenceAnalysis.h:293
llvm::ScalarEvolution
The main scalar evolution driver.
Definition: ScalarEvolution.h:449
llvm::Dependence
Dependence - This class represents a dependence between two memory memory references in a function.
Definition: DependenceAnalysis.h:71
FAM
FunctionAnalysisManager FAM
Definition: PassBuilderBindings.cpp:59
true
basic Basic Alias true
Definition: BasicAliasAnalysis.cpp:1793
llvm::Dependence::isUnordered
bool isUnordered() const
isUnordered - Returns true if dependence is Input
Definition: DependenceAnalysis.h:134
llvm::DependenceAnalysisWrapperPass::getDI
DependenceInfo & getDI() const
Definition: DependenceAnalysis.cpp:164
llvm::Dependence::isScalar
virtual bool isScalar(unsigned Level) const
isScalar - Returns true if a particular level is scalar; that is, if no subscript in the source or de...
Definition: DependenceAnalysis.cpp:257
llvm::Dependence::DVEntry::NONE
@ NONE
Definition: DependenceAnalysis.h:85
llvm::DependenceAnalysisWrapperPass::ID
static char ID
Definition: DependenceAnalysis.h:1003
llvm::DependenceAnalysisWrapperPass::print
void print(raw_ostream &, const Module *=nullptr) const override
print - Print out the internal state of the pass.
Definition: DependenceAnalysis.cpp:211
llvm::dump
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
Definition: SparseBitVector.h:877
llvm::FullDependence::isPeelFirst
bool isPeelFirst(unsigned Level) const override
isPeelFirst - Returns true if peeling the first iteration from this loop will break this dependence.
Definition: DependenceAnalysis.cpp:358
llvm::FullDependence::isScalar
bool isScalar(unsigned Level) const override
isScalar - Returns true if a particular level is scalar; that is, if no subscript in the source or de...
Definition: DependenceAnalysis.cpp:350
llvm::Dependence::DVEntry::Distance
const SCEV * Distance
Definition: DependenceAnalysis.h:98
llvm::Dependence::isAnti
bool isAnti() const
isAnti - Returns true if this is an anti dependence.
Definition: DependenceAnalysis.cpp:248
llvm::Dependence::DVEntry::ALL
@ ALL
Definition: DependenceAnalysis.h:92
F
#define F(x, y, z)
Definition: MD5.cpp:55
llvm::Dependence::DVEntry
Dependence::DVEntry - Each level in the distance/direction vector has a direction (or perhaps a union...
Definition: DependenceAnalysis.h:84
llvm::Dependence::DVEntry::LT
@ LT
Definition: DependenceAnalysis.h:86
llvm::DependenceAnalysisWrapperPass::releaseMemory
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
Definition: DependenceAnalysis.cpp:166
llvm::DependenceAnalysisWrapperPass::DependenceAnalysisWrapperPass
DependenceAnalysisWrapperPass()
Definition: DependenceAnalysis.cpp:147
llvm::AAResults
Definition: AliasAnalysis.h:294
llvm::FullDependence::FullDependence
FullDependence(Instruction *Src, Instruction *Dst, bool LoopIndependent, unsigned Levels)
Definition: DependenceAnalysis.cpp:265
llvm::Dependence::Dependence
Dependence(Instruction *Source, Instruction *Destination)
Definition: DependenceAnalysis.h:77
C
(vector float) vec_cmpeq(*A, *B) C
Definition: README_ALTIVEC.txt:86
llvm::ARM_PROC::A
@ A
Definition: ARMBaseInfo.h:34
Y
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
llvm::createDependenceAnalysisWrapperPass
FunctionPass * createDependenceAnalysisWrapperPass()
createDependenceAnalysisPass - This creates an instance of the DependenceAnalysis wrapper pass.
Definition: DependenceAnalysis.cpp:152
llvm::AnalysisUsage
Represent the analysis usage information of a pass.
Definition: PassAnalysisSupport.h:47
l
This requires reassociating to forms of expressions that are already something that reassoc doesn t think about yet These two functions should generate the same code on big endian int * l
Definition: README.txt:100
false
Definition: StackSlotColoring.cpp:141
llvm::Dependence::DVEntry::GT
@ GT
Definition: DependenceAnalysis.h:89
B
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
llvm::logicalview::LVSortMode::Line
@ Line
llvm::Instruction
Definition: Instruction.h:42
llvm::Dependence::isConfused
virtual bool isConfused() const
isConfused - Returns true if this dependence is confused (the compiler understands nothing and makes ...
Definition: DependenceAnalysis.h:143
llvm::raw_ostream
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
llvm::Dependence::getDistance
virtual const SCEV * getDistance(unsigned Level) const
getDistance - Returns the distance (or NULL) associated with a particular level.
Definition: DependenceAnalysis.h:159
llvm::Dependence::isDirectionNegative
virtual bool isDirectionNegative() const
Check if the direction vector is negative.
Definition: DependenceAnalysis.h:163
llvm::AnalysisManager::Invalidator
API to communicate dependencies between analyses during invalidation.
Definition: PassManager.h:661
llvm::DependenceInfo::invalidate
bool invalidate(Function &F, const PreservedAnalyses &PA, FunctionAnalysisManager::Invalidator &Inv)
Handle transitive invalidation when the cached analysis results go away.
Definition: DependenceAnalysis.cpp:3565
llvm::DependenceInfo::getSplitIteration
const SCEV * getSplitIteration(const Dependence &Dep, unsigned Level)
getSplitIteration - Give a dependence that's splittable at some particular level, return the iteratio...
Definition: DependenceAnalysis.cpp:4024
llvm::lltok::Kind
Kind
Definition: LLToken.h:18
X
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
llvm::Dependence::Src
Instruction * Src
Definition: DependenceAnalysis.h:209
llvm::Dependence::isOutput
bool isOutput() const
isOutput - Returns true if this is an output dependence.
Definition: DependenceAnalysis.cpp:236
llvm::DependenceAnalysisPrinterPass
Printer pass to dump DA results.
Definition: DependenceAnalysis.h:987
llvm::LegacyLegalizeActions::Lower
@ Lower
The operation itself must be expressed in terms of simpler actions on this target.
Definition: LegacyLegalizerInfo.h:58
llvm::Dependence::normalize
virtual bool normalize(ScalarEvolution *SE)
If the direction vector is negative, normalize the direction vector to make it non-negative.
Definition: DependenceAnalysis.h:169
llvm::SCEV
This class represents an analyzed expression in the program.
Definition: ScalarEvolution.h:75
llvm::DependenceInfo
DependenceInfo - This class is the main dependence-analysis driver.
Definition: DependenceAnalysis.h:291
llvm::Dependence::DVEntry::EQ
@ EQ
Definition: DependenceAnalysis.h:87
llvm::Dependence::DVEntry::Scalar
bool Scalar
Definition: DependenceAnalysis.h:94
D
static GCRegistry::Add< StatepointGC > D("statepoint-example", "an example strategy for statepoint")
llvm::AnalysisKey
A special type used by analysis passes to provide an address that identifies that particular analysis...
Definition: PassManager.h:69
llvm::pdb::Empty
@ Empty
Definition: PDBTypes.h:395
llvm::Dependence::isPeelLast
virtual bool isPeelLast(unsigned Level) const
isPeelLast - Returns true if peeling the last iteration from this loop will break this dependence.
Definition: DependenceAnalysis.h:177
llvm::Dependence::isConsistent
virtual bool isConsistent() const
isConsistent - Returns true if this dependence is consistent (occurs every time the source and destin...
Definition: DependenceAnalysis.h:147
Ptr
@ Ptr
Definition: TargetLibraryInfo.cpp:60
llvm::Dependence::operator=
Dependence & operator=(Dependence &&)=default
llvm::FullDependence::getDistance
const SCEV * getDistance(unsigned Level) const override
getDistance - Returns the distance (or NULL) associated with a particular level.
Definition: DependenceAnalysis.cpp:341
llvm::Module
A Module instance is used to store all the information related to an LLVM module.
Definition: Module.h:65
llvm::Dependence::isPeelFirst
virtual bool isPeelFirst(unsigned Level) const
isPeelFirst - Returns true if peeling the first iteration from this loop will break this dependence.
Definition: DependenceAnalysis.h:173
llvm::AnalysisInfoMixin
A CRTP mix-in that provides informational APIs needed for analysis passes.
Definition: PassManager.h:394
llvm::Dependence::getDst
Instruction * getDst() const
getDst - Returns the destination instruction for this dependence.
Definition: DependenceAnalysis.h:110
llvm::Dependence::isInput
bool isInput() const
isInput - Returns true if this is an input dependence.
Definition: DependenceAnalysis.cpp:230
llvm::Sched::Source
@ Source
Definition: TargetLowering.h:99
llvm::LoopInfo
Definition: LoopInfo.h:1108
llvm::FullDependence::normalize
bool normalize(ScalarEvolution *SE) override
If the direction vector is negative, normalize the direction vector to make it non-negative.
Definition: DependenceAnalysis.cpp:303
llvm::FullDependence::isPeelLast
bool isPeelLast(unsigned Level) const override
isPeelLast - Returns true if peeling the last iteration from this loop will break this dependence.
Definition: DependenceAnalysis.cpp:366
llvm::DependenceAnalysis
AnalysisPass to compute dependence information in a function.
Definition: DependenceAnalysis.h:976
S
add sub stmia L5 ldr r0 bl L_printf $stub Instead of a and a wouldn t it be better to do three moves *Return an aggregate type is even return S
Definition: README.txt:210
llvm::Dependence::DVEntry::Direction
unsigned char Direction
Definition: DependenceAnalysis.h:93
llvm::Dependence::setNextPredecessor
void setNextPredecessor(const Dependence *pred)
setNextPredecessor - Sets the value of the NextPredecessor field.
Definition: DependenceAnalysis.h:198
llvm::DependenceAnalysis::run
Result run(Function &F, FunctionAnalysisManager &FAM)
Definition: DependenceAnalysis.cpp:128
llvm::Dependence::DVEntry::NE
@ NE
Definition: DependenceAnalysis.h:90
llvm::FullDependence::isDirectionNegative
bool isDirectionNegative() const override
Check if the direction vector is negative.
Definition: DependenceAnalysis.cpp:290
llvm::Dependence::setNextSuccessor
void setNextSuccessor(const Dependence *succ)
setNextSuccessor - Sets the value of the NextSuccessor field.
Definition: DependenceAnalysis.h:202
llvm::Dependence::DVEntry::Splitable
bool Splitable
Definition: DependenceAnalysis.h:97
Direction
Loop::LoopBounds::Direction Direction
Definition: LoopInfo.cpp:230
llvm::TargetStackID::Value
Value
Definition: TargetFrameLowering.h:27
PassManager.h
llvm::Dependence::Dst
Instruction * Dst
Definition: DependenceAnalysis.h:209
llvm::Dependence::Dependence
Dependence(Dependence &&)=default
llvm::DependenceInfo::depends
std::unique_ptr< Dependence > depends(Instruction *Src, Instruction *Dst, bool PossiblyLoopIndependent)
depends - Tests for a dependence between the Src and Dst instructions.
Definition: DependenceAnalysis.cpp:3590
llvm::Dependence::getDirection
virtual unsigned getDirection(unsigned Level) const
getDirection - Returns the direction associated with a particular level.
Definition: DependenceAnalysis.h:155
Instructions.h
llvm::Dependence::isOrdered
bool isOrdered() const
isOrdered - Returns true if dependence is Output, Flow, or Anti
Definition: DependenceAnalysis.h:130
SmallBitVector.h
llvm::Dependence::getNextPredecessor
const Dependence * getNextPredecessor() const
getNextPredecessor - Returns the value of the NextPredecessor field.
Definition: DependenceAnalysis.h:190
llvm::FullDependence::isLoopIndependent
bool isLoopIndependent() const override
isLoopIndependent - Returns true if this is a loop-independent dependence.
Definition: DependenceAnalysis.h:231
llvm::FullDependence::getDirection
unsigned getDirection(unsigned Level) const override
getDirection - Returns the direction associated with a particular level.
Definition: DependenceAnalysis.cpp:334
llvm::AnalysisManager
A container for analyses that lazily runs them and caches their results.
Definition: InstructionSimplify.h:42
pred
hexagon gen pred
Definition: HexagonGenPredicate.cpp:134
llvm::FunctionPass
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:308
llvm::DependenceAnalysisPrinterPass::DependenceAnalysisPrinterPass
DependenceAnalysisPrinterPass(raw_ostream &OS, bool NormalizeResults=false)
Definition: DependenceAnalysis.h:989
llvm::Dependence::DVEntry::DVEntry
DVEntry()
Definition: DependenceAnalysis.h:99
llvm::FullDependence::getLevels
unsigned getLevels() const override
getLevels - Returns the number of common loops surrounding the source and destination of the dependen...
Definition: DependenceAnalysis.h:244
llvm::DependenceAnalysis::Result
DependenceInfo Result
Definition: DependenceAnalysis.h:978
llvm::Dependence::isLoopIndependent
virtual bool isLoopIndependent() const
isLoopIndependent - Returns true if this is a loop-independent dependence.
Definition: DependenceAnalysis.h:138
llvm::SystemZICMP::Any
@ Any
Definition: SystemZISelLowering.h:378
llvm::Dependence::getNextSuccessor
const Dependence * getNextSuccessor() const
getNextSuccessor - Returns the value of the NextSuccessor field.
Definition: DependenceAnalysis.h:194
llvm::DependenceAnalysisPrinterPass::run
PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM)
Definition: DependenceAnalysis.cpp:218
llvm::Dependence::getSrc
Instruction * getSrc() const
getSrc - Returns the source instruction for this dependence.
Definition: DependenceAnalysis.h:106
llvm::FullDependence
FullDependence - This class represents a dependence between two memory references in a function.
Definition: DependenceAnalysis.h:224
llvm::DependenceAnalysisWrapperPass::runOnFunction
bool runOnFunction(Function &F) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass.
Definition: DependenceAnalysis.cpp:156
llvm::Dependence::DVEntry::PeelFirst
bool PeelFirst
Definition: DependenceAnalysis.h:95
llvm::Dependence::DVEntry::PeelLast
bool PeelLast
Definition: DependenceAnalysis.h:96