LLVM  9.0.0svn
ValueTracking.h
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1 //===- llvm/Analysis/ValueTracking.h - Walk computations --------*- 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 // This file contains routines that help analyze properties that chains of
10 // computations have.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_ANALYSIS_VALUETRACKING_H
15 #define LLVM_ANALYSIS_VALUETRACKING_H
16 
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/Optional.h"
19 #include "llvm/IR/CallSite.h"
20 #include "llvm/IR/Constants.h"
21 #include "llvm/IR/Instruction.h"
22 #include "llvm/IR/Intrinsics.h"
23 #include <cassert>
24 #include <cstdint>
25 
26 namespace llvm {
27 
28 class AddOperator;
29 class APInt;
30 class AssumptionCache;
31 class DataLayout;
32 class DominatorTree;
33 class GEPOperator;
34 class IntrinsicInst;
35 struct KnownBits;
36 class Loop;
37 class LoopInfo;
38 class MDNode;
39 class OptimizationRemarkEmitter;
40 class StringRef;
41 class TargetLibraryInfo;
42 class Value;
43 
44  /// Determine which bits of V are known to be either zero or one and return
45  /// them in the KnownZero/KnownOne bit sets.
46  ///
47  /// This function is defined on values with integer type, values with pointer
48  /// type, and vectors of integers. In the case
49  /// where V is a vector, the known zero and known one values are the
50  /// same width as the vector element, and the bit is set only if it is true
51  /// for all of the elements in the vector.
52  void computeKnownBits(const Value *V, KnownBits &Known,
53  const DataLayout &DL, unsigned Depth = 0,
54  AssumptionCache *AC = nullptr,
55  const Instruction *CxtI = nullptr,
56  const DominatorTree *DT = nullptr,
57  OptimizationRemarkEmitter *ORE = nullptr,
58  bool UseInstrInfo = true);
59 
60  /// Returns the known bits rather than passing by reference.
61  KnownBits computeKnownBits(const Value *V, const DataLayout &DL,
62  unsigned Depth = 0, AssumptionCache *AC = nullptr,
63  const Instruction *CxtI = nullptr,
64  const DominatorTree *DT = nullptr,
65  OptimizationRemarkEmitter *ORE = nullptr,
66  bool UseInstrInfo = true);
67 
68  /// Compute known bits from the range metadata.
69  /// \p KnownZero the set of bits that are known to be zero
70  /// \p KnownOne the set of bits that are known to be one
71  void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
72  KnownBits &Known);
73 
74  /// Return true if LHS and RHS have no common bits set.
75  bool haveNoCommonBitsSet(const Value *LHS, const Value *RHS,
76  const DataLayout &DL,
77  AssumptionCache *AC = nullptr,
78  const Instruction *CxtI = nullptr,
79  const DominatorTree *DT = nullptr,
80  bool UseInstrInfo = true);
81 
82  /// Return true if the given value is known to have exactly one bit set when
83  /// defined. For vectors return true if every element is known to be a power
84  /// of two when defined. Supports values with integer or pointer type and
85  /// vectors of integers. If 'OrZero' is set, then return true if the given
86  /// value is either a power of two or zero.
87  bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL,
88  bool OrZero = false, unsigned Depth = 0,
89  AssumptionCache *AC = nullptr,
90  const Instruction *CxtI = nullptr,
91  const DominatorTree *DT = nullptr,
92  bool UseInstrInfo = true);
93 
94  bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI);
95 
96  /// Return true if the given value is known to be non-zero when defined. For
97  /// vectors, return true if every element is known to be non-zero when
98  /// defined. For pointers, if the context instruction and dominator tree are
99  /// specified, perform context-sensitive analysis and return true if the
100  /// pointer couldn't possibly be null at the specified instruction.
101  /// Supports values with integer or pointer type and vectors of integers.
102  bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth = 0,
103  AssumptionCache *AC = nullptr,
104  const Instruction *CxtI = nullptr,
105  const DominatorTree *DT = nullptr,
106  bool UseInstrInfo = true);
107 
108  /// Return true if the two given values are negation.
109  /// Currently can recoginze Value pair:
110  /// 1: <X, Y> if X = sub (0, Y) or Y = sub (0, X)
111  /// 2: <X, Y> if X = sub (A, B) and Y = sub (B, A)
112  bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW = false);
113 
114  /// Returns true if the give value is known to be non-negative.
115  bool isKnownNonNegative(const Value *V, const DataLayout &DL,
116  unsigned Depth = 0,
117  AssumptionCache *AC = nullptr,
118  const Instruction *CxtI = nullptr,
119  const DominatorTree *DT = nullptr,
120  bool UseInstrInfo = true);
121 
122  /// Returns true if the given value is known be positive (i.e. non-negative
123  /// and non-zero).
124  bool isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth = 0,
125  AssumptionCache *AC = nullptr,
126  const Instruction *CxtI = nullptr,
127  const DominatorTree *DT = nullptr,
128  bool UseInstrInfo = true);
129 
130  /// Returns true if the given value is known be negative (i.e. non-positive
131  /// and non-zero).
132  bool isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth = 0,
133  AssumptionCache *AC = nullptr,
134  const Instruction *CxtI = nullptr,
135  const DominatorTree *DT = nullptr,
136  bool UseInstrInfo = true);
137 
138  /// Return true if the given values are known to be non-equal when defined.
139  /// Supports scalar integer types only.
140  bool isKnownNonEqual(const Value *V1, const Value *V2, const DataLayout &DL,
141  AssumptionCache *AC = nullptr,
142  const Instruction *CxtI = nullptr,
143  const DominatorTree *DT = nullptr,
144  bool UseInstrInfo = true);
145 
146  /// Return true if 'V & Mask' is known to be zero. We use this predicate to
147  /// simplify operations downstream. Mask is known to be zero for bits that V
148  /// cannot have.
149  ///
150  /// This function is defined on values with integer type, values with pointer
151  /// type, and vectors of integers. In the case
152  /// where V is a vector, the mask, known zero, and known one values are the
153  /// same width as the vector element, and the bit is set only if it is true
154  /// for all of the elements in the vector.
155  bool MaskedValueIsZero(const Value *V, const APInt &Mask,
156  const DataLayout &DL,
157  unsigned Depth = 0, AssumptionCache *AC = nullptr,
158  const Instruction *CxtI = nullptr,
159  const DominatorTree *DT = nullptr,
160  bool UseInstrInfo = true);
161 
162  /// Return the number of times the sign bit of the register is replicated into
163  /// the other bits. We know that at least 1 bit is always equal to the sign
164  /// bit (itself), but other cases can give us information. For example,
165  /// immediately after an "ashr X, 2", we know that the top 3 bits are all
166  /// equal to each other, so we return 3. For vectors, return the number of
167  /// sign bits for the vector element with the mininum number of known sign
168  /// bits.
169  unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL,
170  unsigned Depth = 0, AssumptionCache *AC = nullptr,
171  const Instruction *CxtI = nullptr,
172  const DominatorTree *DT = nullptr,
173  bool UseInstrInfo = true);
174 
175  /// This function computes the integer multiple of Base that equals V. If
176  /// successful, it returns true and returns the multiple in Multiple. If
177  /// unsuccessful, it returns false. Also, if V can be simplified to an
178  /// integer, then the simplified V is returned in Val. Look through sext only
179  /// if LookThroughSExt=true.
180  bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
181  bool LookThroughSExt = false,
182  unsigned Depth = 0);
183 
184  /// Map a call instruction to an intrinsic ID. Libcalls which have equivalent
185  /// intrinsics are treated as-if they were intrinsics.
186  Intrinsic::ID getIntrinsicForCallSite(ImmutableCallSite ICS,
187  const TargetLibraryInfo *TLI);
188 
189  /// Return true if we can prove that the specified FP value is never equal to
190  /// -0.0.
191  bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
192  unsigned Depth = 0);
193 
194  /// Return true if we can prove that the specified FP value is either NaN or
195  /// never less than -0.0.
196  ///
197  /// NaN --> true
198  /// +0 --> true
199  /// -0 --> true
200  /// x > +0 --> true
201  /// x < -0 --> false
202  bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI);
203 
204  /// Return true if the floating-point scalar value is not a NaN or if the
205  /// floating-point vector value has no NaN elements. Return false if a value
206  /// could ever be NaN.
207  bool isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
208  unsigned Depth = 0);
209 
210  /// Return true if we can prove that the specified FP value's sign bit is 0.
211  ///
212  /// NaN --> true/false (depending on the NaN's sign bit)
213  /// +0 --> true
214  /// -0 --> false
215  /// x > +0 --> true
216  /// x < -0 --> false
217  bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI);
218 
219  /// If the specified value can be set by repeating the same byte in memory,
220  /// return the i8 value that it is represented with. This is true for all i8
221  /// values obviously, but is also true for i32 0, i32 -1, i16 0xF0F0, double
222  /// 0.0 etc. If the value can't be handled with a repeated byte store (e.g.
223  /// i16 0x1234), return null. If the value is entirely undef and padding,
224  /// return undef.
225  Value *isBytewiseValue(Value *V);
226 
227  /// Given an aggregrate and an sequence of indices, see if the scalar value
228  /// indexed is already around as a register, for example if it were inserted
229  /// directly into the aggregrate.
230  ///
231  /// If InsertBefore is not null, this function will duplicate (modified)
232  /// insertvalues when a part of a nested struct is extracted.
233  Value *FindInsertedValue(Value *V,
234  ArrayRef<unsigned> idx_range,
235  Instruction *InsertBefore = nullptr);
236 
237  /// Analyze the specified pointer to see if it can be expressed as a base
238  /// pointer plus a constant offset. Return the base and offset to the caller.
239  Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
240  const DataLayout &DL);
241  inline const Value *GetPointerBaseWithConstantOffset(const Value *Ptr,
242  int64_t &Offset,
243  const DataLayout &DL) {
244  return GetPointerBaseWithConstantOffset(const_cast<Value *>(Ptr), Offset,
245  DL);
246  }
247 
248  /// Returns true if the GEP is based on a pointer to a string (array of
249  // \p CharSize integers) and is indexing into this string.
251  unsigned CharSize = 8);
252 
253  /// Represents offset+length into a ConstantDataArray.
255  /// ConstantDataArray pointer. nullptr indicates a zeroinitializer (a valid
256  /// initializer, it just doesn't fit the ConstantDataArray interface).
258 
259  /// Slice starts at this Offset.
260  uint64_t Offset;
261 
262  /// Length of the slice.
263  uint64_t Length;
264 
265  /// Moves the Offset and adjusts Length accordingly.
266  void move(uint64_t Delta) {
267  assert(Delta < Length);
268  Offset += Delta;
269  Length -= Delta;
270  }
271 
272  /// Convenience accessor for elements in the slice.
273  uint64_t operator[](unsigned I) const {
274  return Array==nullptr ? 0 : Array->getElementAsInteger(I + Offset);
275  }
276  };
277 
278  /// Returns true if the value \p V is a pointer into a ConstantDataArray.
279  /// If successful \p Slice will point to a ConstantDataArray info object
280  /// with an appropriate offset.
282  unsigned ElementSize, uint64_t Offset = 0);
283 
284  /// This function computes the length of a null-terminated C string pointed to
285  /// by V. If successful, it returns true and returns the string in Str. If
286  /// unsuccessful, it returns false. This does not include the trailing null
287  /// character by default. If TrimAtNul is set to false, then this returns any
288  /// trailing null characters as well as any other characters that come after
289  /// it.
290  bool getConstantStringInfo(const Value *V, StringRef &Str,
291  uint64_t Offset = 0, bool TrimAtNul = true);
292 
293  /// If we can compute the length of the string pointed to by the specified
294  /// pointer, return 'len+1'. If we can't, return 0.
295  uint64_t GetStringLength(const Value *V, unsigned CharSize = 8);
296 
297  /// This function returns call pointer argument that is considered the same by
298  /// aliasing rules. You CAN'T use it to replace one value with another.
301  return const_cast<Value *>(getArgumentAliasingToReturnedPointer(
302  const_cast<const CallBase *>(Call)));
303  }
304 
305  // {launder,strip}.invariant.group returns pointer that aliases its argument,
306  // and it only captures pointer by returning it.
307  // These intrinsics are not marked as nocapture, because returning is
308  // considered as capture. The arguments are not marked as returned neither,
309  // because it would make it useless.
311  const CallBase *Call);
312 
313  /// This method strips off any GEP address adjustments and pointer casts from
314  /// the specified value, returning the original object being addressed. Note
315  /// that the returned value has pointer type if the specified value does. If
316  /// the MaxLookup value is non-zero, it limits the number of instructions to
317  /// be stripped off.
318  Value *GetUnderlyingObject(Value *V, const DataLayout &DL,
319  unsigned MaxLookup = 6);
320  inline const Value *GetUnderlyingObject(const Value *V, const DataLayout &DL,
321  unsigned MaxLookup = 6) {
322  return GetUnderlyingObject(const_cast<Value *>(V), DL, MaxLookup);
323  }
324 
325  /// This method is similar to GetUnderlyingObject except that it can
326  /// look through phi and select instructions and return multiple objects.
327  ///
328  /// If LoopInfo is passed, loop phis are further analyzed. If a pointer
329  /// accesses different objects in each iteration, we don't look through the
330  /// phi node. E.g. consider this loop nest:
331  ///
332  /// int **A;
333  /// for (i)
334  /// for (j) {
335  /// A[i][j] = A[i-1][j] * B[j]
336  /// }
337  ///
338  /// This is transformed by Load-PRE to stash away A[i] for the next iteration
339  /// of the outer loop:
340  ///
341  /// Curr = A[0]; // Prev_0
342  /// for (i: 1..N) {
343  /// Prev = Curr; // Prev = PHI (Prev_0, Curr)
344  /// Curr = A[i];
345  /// for (j: 0..N) {
346  /// Curr[j] = Prev[j] * B[j]
347  /// }
348  /// }
349  ///
350  /// Since A[i] and A[i-1] are independent pointers, getUnderlyingObjects
351  /// should not assume that Curr and Prev share the same underlying object thus
352  /// it shouldn't look through the phi above.
354  const DataLayout &DL, LoopInfo *LI = nullptr,
355  unsigned MaxLookup = 6);
356 
357  /// This is a wrapper around GetUnderlyingObjects and adds support for basic
358  /// ptrtoint+arithmetic+inttoptr sequences.
360  SmallVectorImpl<Value *> &Objects,
361  const DataLayout &DL);
362 
363  /// Return true if the only users of this pointer are lifetime markers.
364  bool onlyUsedByLifetimeMarkers(const Value *V);
365 
366  /// Return true if the instruction does not have any effects besides
367  /// calculating the result and does not have undefined behavior.
368  ///
369  /// This method never returns true for an instruction that returns true for
370  /// mayHaveSideEffects; however, this method also does some other checks in
371  /// addition. It checks for undefined behavior, like dividing by zero or
372  /// loading from an invalid pointer (but not for undefined results, like a
373  /// shift with a shift amount larger than the width of the result). It checks
374  /// for malloc and alloca because speculatively executing them might cause a
375  /// memory leak. It also returns false for instructions related to control
376  /// flow, specifically terminators and PHI nodes.
377  ///
378  /// If the CtxI is specified this method performs context-sensitive analysis
379  /// and returns true if it is safe to execute the instruction immediately
380  /// before the CtxI.
381  ///
382  /// If the CtxI is NOT specified this method only looks at the instruction
383  /// itself and its operands, so if this method returns true, it is safe to
384  /// move the instruction as long as the correct dominance relationships for
385  /// the operands and users hold.
386  ///
387  /// This method can return true for instructions that read memory;
388  /// for such instructions, moving them may change the resulting value.
389  bool isSafeToSpeculativelyExecute(const Value *V,
390  const Instruction *CtxI = nullptr,
391  const DominatorTree *DT = nullptr);
392 
393  /// Returns true if the result or effects of the given instructions \p I
394  /// depend on or influence global memory.
395  /// Memory dependence arises for example if the instruction reads from
396  /// memory or may produce effects or undefined behaviour. Memory dependent
397  /// instructions generally cannot be reorderd with respect to other memory
398  /// dependent instructions or moved into non-dominated basic blocks.
399  /// Instructions which just compute a value based on the values of their
400  /// operands are not memory dependent.
401  bool mayBeMemoryDependent(const Instruction &I);
402 
403  /// Return true if it is an intrinsic that cannot be speculated but also
404  /// cannot trap.
405  bool isAssumeLikeIntrinsic(const Instruction *I);
406 
407  /// Return true if it is valid to use the assumptions provided by an
408  /// assume intrinsic, I, at the point in the control-flow identified by the
409  /// context instruction, CxtI.
410  bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI,
411  const DominatorTree *DT = nullptr);
412 
414 
416  const Value *RHS,
417  const DataLayout &DL,
418  AssumptionCache *AC,
419  const Instruction *CxtI,
420  const DominatorTree *DT,
421  bool UseInstrInfo = true);
422  OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS,
423  const DataLayout &DL,
424  AssumptionCache *AC,
425  const Instruction *CxtI,
426  const DominatorTree *DT,
427  bool UseInstrInfo = true);
429  const Value *RHS,
430  const DataLayout &DL,
431  AssumptionCache *AC,
432  const Instruction *CxtI,
433  const DominatorTree *DT,
434  bool UseInstrInfo = true);
435  OverflowResult computeOverflowForSignedAdd(const Value *LHS, const Value *RHS,
436  const DataLayout &DL,
437  AssumptionCache *AC = nullptr,
438  const Instruction *CxtI = nullptr,
439  const DominatorTree *DT = nullptr);
440  /// This version also leverages the sign bit of Add if known.
442  const DataLayout &DL,
443  AssumptionCache *AC = nullptr,
444  const Instruction *CxtI = nullptr,
445  const DominatorTree *DT = nullptr);
447  const DataLayout &DL,
448  AssumptionCache *AC,
449  const Instruction *CxtI,
450  const DominatorTree *DT);
451  OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS,
452  const DataLayout &DL,
453  AssumptionCache *AC,
454  const Instruction *CxtI,
455  const DominatorTree *DT);
456 
457  /// Returns true if the arithmetic part of the \p II 's result is
458  /// used only along the paths control dependent on the computation
459  /// not overflowing, \p II being an <op>.with.overflow intrinsic.
461  const DominatorTree &DT);
462 
463  /// Return true if this function can prove that the instruction I will
464  /// always transfer execution to one of its successors (including the next
465  /// instruction that follows within a basic block). E.g. this is not
466  /// guaranteed for function calls that could loop infinitely.
467  ///
468  /// In other words, this function returns false for instructions that may
469  /// transfer execution or fail to transfer execution in a way that is not
470  /// captured in the CFG nor in the sequence of instructions within a basic
471  /// block.
472  ///
473  /// Undefined behavior is assumed not to happen, so e.g. division is
474  /// guaranteed to transfer execution to the following instruction even
475  /// though division by zero might cause undefined behavior.
477 
478  /// Returns true if this block does not contain a potential implicit exit.
479  /// This is equivelent to saying that all instructions within the basic block
480  /// are guaranteed to transfer execution to their successor within the basic
481  /// block. This has the same assumptions w.r.t. undefined behavior as the
482  /// instruction variant of this function.
484 
485  /// Return true if this function can prove that the instruction I
486  /// is executed for every iteration of the loop L.
487  ///
488  /// Note that this currently only considers the loop header.
490  const Loop *L);
491 
492  /// Return true if this function can prove that I is guaranteed to yield
493  /// full-poison (all bits poison) if at least one of its operands are
494  /// full-poison (all bits poison).
495  ///
496  /// The exact rules for how poison propagates through instructions have
497  /// not been settled as of 2015-07-10, so this function is conservative
498  /// and only considers poison to be propagated in uncontroversial
499  /// cases. There is no attempt to track values that may be only partially
500  /// poison.
501  bool propagatesFullPoison(const Instruction *I);
502 
503  /// Return either nullptr or an operand of I such that I will trigger
504  /// undefined behavior if I is executed and that operand has a full-poison
505  /// value (all bits poison).
507 
508  /// Return true if this function can prove that if PoisonI is executed
509  /// and yields a full-poison value (all bits poison), then that will
510  /// trigger undefined behavior.
511  ///
512  /// Note that this currently only considers the basic block that is
513  /// the parent of I.
514  bool programUndefinedIfFullPoison(const Instruction *PoisonI);
515 
516  /// Specific patterns of select instructions we can match.
519  SPF_SMIN, /// Signed minimum
520  SPF_UMIN, /// Unsigned minimum
521  SPF_SMAX, /// Signed maximum
522  SPF_UMAX, /// Unsigned maximum
523  SPF_FMINNUM, /// Floating point minnum
524  SPF_FMAXNUM, /// Floating point maxnum
525  SPF_ABS, /// Absolute value
526  SPF_NABS /// Negated absolute value
527  };
528 
529  /// Behavior when a floating point min/max is given one NaN and one
530  /// non-NaN as input.
532  SPNB_NA = 0, /// NaN behavior not applicable.
533  SPNB_RETURNS_NAN, /// Given one NaN input, returns the NaN.
534  SPNB_RETURNS_OTHER, /// Given one NaN input, returns the non-NaN.
535  SPNB_RETURNS_ANY /// Given one NaN input, can return either (or
536  /// it has been determined that no operands can
537  /// be NaN).
538  };
539 
542  SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is
543  /// SPF_FMINNUM or SPF_FMAXNUM.
544  bool Ordered; /// When implementing this min/max pattern as
545  /// fcmp; select, does the fcmp have to be
546  /// ordered?
547 
548  /// Return true if \p SPF is a min or a max pattern.
549  static bool isMinOrMax(SelectPatternFlavor SPF) {
550  return SPF != SPF_UNKNOWN && SPF != SPF_ABS && SPF != SPF_NABS;
551  }
552  };
553 
554  /// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
555  /// and providing the out parameter results if we successfully match.
556  ///
557  /// For ABS/NABS, LHS will be set to the input to the abs idiom. RHS will be
558  /// the negation instruction from the idiom.
559  ///
560  /// If CastOp is not nullptr, also match MIN/MAX idioms where the type does
561  /// not match that of the original select. If this is the case, the cast
562  /// operation (one of Trunc,SExt,Zext) that must be done to transform the
563  /// type of LHS and RHS into the type of V is returned in CastOp.
564  ///
565  /// For example:
566  /// %1 = icmp slt i32 %a, i32 4
567  /// %2 = sext i32 %a to i64
568  /// %3 = select i1 %1, i64 %2, i64 4
569  ///
570  /// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt
571  ///
573  Instruction::CastOps *CastOp = nullptr,
574  unsigned Depth = 0);
575  inline SelectPatternResult
576  matchSelectPattern(const Value *V, const Value *&LHS, const Value *&RHS,
577  Instruction::CastOps *CastOp = nullptr) {
578  Value *L = const_cast<Value*>(LHS);
579  Value *R = const_cast<Value*>(RHS);
580  auto Result = matchSelectPattern(const_cast<Value*>(V), L, R);
581  LHS = L;
582  RHS = R;
583  return Result;
584  }
585 
586  /// Return the canonical comparison predicate for the specified
587  /// minimum/maximum flavor.
589  bool Ordered = false);
590 
591  /// Return the inverse minimum/maximum flavor of the specified flavor.
592  /// For example, signed minimum is the inverse of signed maximum.
594 
595  /// Return the canonical inverse comparison predicate for the specified
596  /// minimum/maximum flavor.
598 
599  /// Return true if RHS is known to be implied true by LHS. Return false if
600  /// RHS is known to be implied false by LHS. Otherwise, return None if no
601  /// implication can be made.
602  /// A & B must be i1 (boolean) values or a vector of such values. Note that
603  /// the truth table for implication is the same as <=u on i1 values (but not
604  /// <=s!). The truth table for both is:
605  /// | T | F (B)
606  /// T | T | F
607  /// F | T | T
608  /// (A)
609  Optional<bool> isImpliedCondition(const Value *LHS, const Value *RHS,
610  const DataLayout &DL, bool LHSIsTrue = true,
611  unsigned Depth = 0);
612 
613  /// Return the boolean condition value in the context of the given instruction
614  /// if it is known based on dominating conditions.
616  const Instruction *ContextI,
617  const DataLayout &DL);
618 } // end namespace llvm
619 
620 #endif // LLVM_ANALYSIS_VALUETRACKING_H
const Value * getGuaranteedNonFullPoisonOp(const Instruction *I)
Return either nullptr or an operand of I such that I will trigger undefined behavior if I is executed...
bool isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Returns true if the given value is known be positive (i.e.
void computeKnownBits(const Value *V, KnownBits &Known, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, OptimizationRemarkEmitter *ORE=nullptr, bool UseInstrInfo=true)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:110
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI)
Unsigned minimum.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Value * isBytewiseValue(Value *V)
If the specified value can be set by repeating the same byte in memory, return the i8 value that it i...
Optional< bool > isImpliedByDomCondition(const Value *Cond, const Instruction *ContextI, const DataLayout &DL)
Return the boolean condition value in the context of the given instruction if it is known based on do...
bool isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(const CallBase *Call)
A cache of @llvm.assume calls within a function.
bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI, const DominatorTree *DT=nullptr)
Return true if it is valid to use the assumptions provided by an assume intrinsic, I, at the point in the control-flow identified by the context instruction, CxtI.
SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF)
Return the inverse minimum/maximum flavor of the specified flavor.
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1013
Hexagon Common GEP
bool isGEPBasedOnPointerToString(const GEPOperator *GEP, unsigned CharSize=8)
Returns true if the GEP is based on a pointer to a string (array of.
uint64_t Offset
Slice starts at this Offset.
bool Ordered
Only applicable if Flavor is SPF_FMINNUM or SPF_FMAXNUM.
bool propagatesFullPoison(const Instruction *I)
Return true if this function can prove that I is guaranteed to yield full-poison (all bits poison) if...
Signed maximum.
Intrinsic::ID getIntrinsicForCallSite(ImmutableCallSite ICS, const TargetLibraryInfo *TLI)
Map a call instruction to an intrinsic ID.
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL, bool OrZero=false, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if the given value is known to have exactly one bit set when defined. ...
Absolute value.
OverflowResult computeOverflowForUnsignedAdd(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, bool UseInstrInfo=true)
NaN behavior not applicable.
bool MaskedValueIsZero(const Value *V, const APInt &Mask, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if &#39;V & Mask&#39; is known to be zero.
bool programUndefinedIfFullPoison(const Instruction *PoisonI)
Return true if this function can prove that if PoisonI is executed and yields a full-poison value (al...
uint64_t operator[](unsigned I) const
Convenience accessor for elements in the slice.
const ConstantDataArray * Array
ConstantDataArray pointer.
Value * GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, const DataLayout &DL)
Analyze the specified pointer to see if it can be expressed as a base pointer plus a constant offset...
OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, bool UseInstrInfo=true)
bool isKnownNonNegative(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Returns true if the give value is known to be non-negative.
uint64_t GetStringLength(const Value *V, unsigned CharSize=8)
If we can compute the length of the string pointed to by the specified pointer, return &#39;len+1&#39;...
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:144
bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI, unsigned Depth=0)
Return true if we can prove that the specified FP value is never equal to -0.0.
bool getConstantDataArrayInfo(const Value *V, ConstantDataArraySlice &Slice, unsigned ElementSize, uint64_t Offset=0)
Returns true if the value V is a pointer into a ConstantDataArray.
unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return the number of times the sign bit of the register is replicated into the other bits...
bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I)
Return true if this function can prove that the instruction I will always transfer execution to one o...
OverflowResult computeOverflowForSignedAdd(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW=false)
Return true if the two given values are negation.
An array constant whose element type is a simple 1/2/4/8-byte integer or float/double, and whose elements are just simple data values (i.e.
Definition: Constants.h:689
LLVM Basic Block Representation.
Definition: BasicBlock.h:57
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool onlyUsedByLifetimeMarkers(const Value *V)
Return true if the only users of this pointer are lifetime markers.
bool getUnderlyingObjectsForCodeGen(const Value *V, SmallVectorImpl< Value *> &Objects, const DataLayout &DL)
This is a wrapper around GetUnderlyingObjects and adds support for basic ptrtoint+arithmetic+inttoptr...
bool isOverflowIntrinsicNoWrap(const IntrinsicInst *II, const DominatorTree &DT)
Returns true if the arithmetic part of the II &#39;s result is used only along the paths control dependen...
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:645
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered=false)
Return the canonical comparison predicate for the specified minimum/maximum flavor.
SelectPatternNaNBehavior
Behavior when a floating point min/max is given one NaN and one non-NaN as input. ...
Represents offset+length into a ConstantDataArray.
CmpInst::Predicate getInverseMinMaxPred(SelectPatternFlavor SPF)
Return the canonical inverse comparison predicate for the specified minimum/maximum flavor...
bool isAssumeLikeIntrinsic(const Instruction *I)
Return true if it is an intrinsic that cannot be speculated but also cannot trap. ...
Value * GetUnderlyingObject(Value *V, const DataLayout &DL, unsigned MaxLookup=6)
This method strips off any GEP address adjustments and pointer casts from the specified value...
const Value * getArgumentAliasingToReturnedPointer(const CallBase *Call)
This function returns call pointer argument that is considered the same by aliasing rules...
Value * FindInsertedValue(Value *V, ArrayRef< unsigned > idx_range, Instruction *InsertBefore=nullptr)
Given an aggregrate and an sequence of indices, see if the scalar value indexed is already around as ...
Floating point maxnum.
Given one NaN input, returns the non-NaN.
SelectPatternFlavor Flavor
Unsigned maximum.
uint64_t getElementAsInteger(unsigned i) const
If this is a sequential container of integers (of any size), return the specified element in the low ...
Definition: Constants.cpp:2679
uint64_t Length
Length of the slice.
SelectPatternFlavor
Specific patterns of select instructions we can match.
Floating point minnum.
SelectPatternNaNBehavior NaNBehavior
void computeKnownBitsFromRangeMetadata(const MDNode &Ranges, KnownBits &Known)
Compute known bits from the range metadata.
bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if the given value is known to be non-zero when defined.
bool mayBeMemoryDependent(const Instruction &I)
Returns true if the result or effects of the given instructions I depend on or influence global memor...
OverflowResult
bool isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Returns true if the given value is known be negative (i.e.
static bool isMinOrMax(SelectPatternFlavor SPF)
When implementing this min/max pattern as fcmp; select, does the fcmp have to be ordered?
Represents a single loop in the control flow graph.
Definition: LoopInfo.h:464
bool isKnownNonEqual(const Value *V1, const Value *V2, const DataLayout &DL, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if the given values are known to be non-equal when defined.
#define I(x, y, z)
Definition: MD5.cpp:58
bool haveNoCommonBitsSet(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Return true if LHS and RHS have no common bits set.
bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI)
Return true if we can prove that the specified FP value&#39;s sign bit is 0.
bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple, bool LookThroughSExt=false, unsigned Depth=0)
This function computes the integer multiple of Base that equals V.
bool isGuaranteedToExecuteForEveryIteration(const Instruction *I, const Loop *L)
Return true if this function can prove that the instruction I is executed for every iteration of the ...
bool isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI, unsigned Depth=0)
Return true if the floating-point scalar value is not a NaN or if the floating-point vector value has...
Signed minimum.
Optional< bool > isImpliedCondition(const Value *LHS, const Value *RHS, const DataLayout &DL, bool LHSIsTrue=true, unsigned Depth=0)
Return true if RHS is known to be implied true by LHS.
bool getConstantStringInfo(const Value *V, StringRef &Str, uint64_t Offset=0, bool TrimAtNul=true)
This function computes the length of a null-terminated C string pointed to by V.
void GetUnderlyingObjects(Value *V, SmallVectorImpl< Value *> &Objects, const DataLayout &DL, LoopInfo *LI=nullptr, unsigned MaxLookup=6)
This method is similar to GetUnderlyingObject except that it can look through phi and select instruct...
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Given one NaN input, returns the NaN.
bool isSafeToSpeculativelyExecute(const Value *V, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr)
Return true if the instruction does not have any effects besides calculating the result and does not ...
LLVM Value Representation.
Definition: Value.h:72
SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS, Instruction::CastOps *CastOp=nullptr, unsigned Depth=0)
Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind and providing the out param...
std::underlying_type< E >::type Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:80
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
void move(uint64_t Delta)
Moves the Offset and adjusts Length accordingly.
OverflowResult computeOverflowForUnsignedMul(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT, bool UseInstrInfo=true)
bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI)
Return true if we can prove that the specified FP value is either NaN or never less than -0...
OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT)
OverflowResult computeOverflowForUnsignedSub(const Value *LHS, const Value *RHS, const DataLayout &DL, AssumptionCache *AC, const Instruction *CxtI, const DominatorTree *DT)
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:43