1 //===- llvm/Analysis/ValueTracking.h - Walk computations --------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 // This file contains routines that help analyze properties that chains of
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_ANALYSIS_VALUETRACKING_H
15 #define LLVM_ANALYSIS_VALUETRACKING_H
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/Optional.h"
19 #include "llvm/ADT/SmallSet.h"
20 #include "llvm/IR/CallSite.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/Instruction.h"
24 #include "llvm/IR/Intrinsics.h"
32 class AssumptionCache;
36 class WithOverflowInst;
41 class OptimizationRemarkEmitter;
43 class TargetLibraryInfo;
46 /// Determine which bits of V are known to be either zero or one and return
47 /// them in the KnownZero/KnownOne bit sets.
49 /// This function is defined on values with integer type, values with pointer
50 /// type, and vectors of integers. In the case
51 /// where V is a vector, the known zero and known one values are the
52 /// same width as the vector element, and the bit is set only if it is true
53 /// for all of the elements in the vector.
54 void computeKnownBits(const Value *V, KnownBits &Known,
55 const DataLayout &DL, unsigned Depth = 0,
56 AssumptionCache *AC = nullptr,
57 const Instruction *CxtI = nullptr,
58 const DominatorTree *DT = nullptr,
59 OptimizationRemarkEmitter *ORE = nullptr,
60 bool UseInstrInfo = true);
62 /// Returns the known bits rather than passing by reference.
63 KnownBits computeKnownBits(const Value *V, const DataLayout &DL,
64 unsigned Depth = 0, AssumptionCache *AC = nullptr,
65 const Instruction *CxtI = nullptr,
66 const DominatorTree *DT = nullptr,
67 OptimizationRemarkEmitter *ORE = nullptr,
68 bool UseInstrInfo = true);
70 /// Compute known bits from the range metadata.
71 /// \p KnownZero the set of bits that are known to be zero
72 /// \p KnownOne the set of bits that are known to be one
73 void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
76 /// Return true if LHS and RHS have no common bits set.
77 bool haveNoCommonBitsSet(const Value *LHS, const Value *RHS,
79 AssumptionCache *AC = nullptr,
80 const Instruction *CxtI = nullptr,
81 const DominatorTree *DT = nullptr,
82 bool UseInstrInfo = true);
84 /// Return true if the given value is known to have exactly one bit set when
85 /// defined. For vectors return true if every element is known to be a power
86 /// of two when defined. Supports values with integer or pointer type and
87 /// vectors of integers. If 'OrZero' is set, then return true if the given
88 /// value is either a power of two or zero.
89 bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL,
90 bool OrZero = false, unsigned Depth = 0,
91 AssumptionCache *AC = nullptr,
92 const Instruction *CxtI = nullptr,
93 const DominatorTree *DT = nullptr,
94 bool UseInstrInfo = true);
96 bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI);
98 /// Return true if the given value is known to be non-zero when defined. For
99 /// vectors, return true if every element is known to be non-zero when
100 /// defined. For pointers, if the context instruction and dominator tree are
101 /// specified, perform context-sensitive analysis and return true if the
102 /// pointer couldn't possibly be null at the specified instruction.
103 /// Supports values with integer or pointer type and vectors of integers.
104 bool isKnownNonZero(const Value *V, const DataLayout &DL, unsigned Depth = 0,
105 AssumptionCache *AC = nullptr,
106 const Instruction *CxtI = nullptr,
107 const DominatorTree *DT = nullptr,
108 bool UseInstrInfo = true);
110 /// Return true if the two given values are negation.
111 /// Currently can recoginze Value pair:
112 /// 1: <X, Y> if X = sub (0, Y) or Y = sub (0, X)
113 /// 2: <X, Y> if X = sub (A, B) and Y = sub (B, A)
114 bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW = false);
116 /// Returns true if the give value is known to be non-negative.
117 bool isKnownNonNegative(const Value *V, const DataLayout &DL,
119 AssumptionCache *AC = nullptr,
120 const Instruction *CxtI = nullptr,
121 const DominatorTree *DT = nullptr,
122 bool UseInstrInfo = true);
124 /// Returns true if the given value is known be positive (i.e. non-negative
126 bool isKnownPositive(const Value *V, const DataLayout &DL, unsigned Depth = 0,
127 AssumptionCache *AC = nullptr,
128 const Instruction *CxtI = nullptr,
129 const DominatorTree *DT = nullptr,
130 bool UseInstrInfo = true);
132 /// Returns true if the given value is known be negative (i.e. non-positive
134 bool isKnownNegative(const Value *V, const DataLayout &DL, unsigned Depth = 0,
135 AssumptionCache *AC = nullptr,
136 const Instruction *CxtI = nullptr,
137 const DominatorTree *DT = nullptr,
138 bool UseInstrInfo = true);
140 /// Return true if the given values are known to be non-equal when defined.
141 /// Supports scalar integer types only.
142 bool isKnownNonEqual(const Value *V1, const Value *V2, const DataLayout &DL,
143 AssumptionCache *AC = nullptr,
144 const Instruction *CxtI = nullptr,
145 const DominatorTree *DT = nullptr,
146 bool UseInstrInfo = true);
148 /// Return true if 'V & Mask' is known to be zero. We use this predicate to
149 /// simplify operations downstream. Mask is known to be zero for bits that V
152 /// This function is defined on values with integer type, values with pointer
153 /// type, and vectors of integers. In the case
154 /// where V is a vector, the mask, known zero, and known one values are the
155 /// same width as the vector element, and the bit is set only if it is true
156 /// for all of the elements in the vector.
157 bool MaskedValueIsZero(const Value *V, const APInt &Mask,
158 const DataLayout &DL,
159 unsigned Depth = 0, AssumptionCache *AC = nullptr,
160 const Instruction *CxtI = nullptr,
161 const DominatorTree *DT = nullptr,
162 bool UseInstrInfo = true);
164 /// Return the number of times the sign bit of the register is replicated into
165 /// the other bits. We know that at least 1 bit is always equal to the sign
166 /// bit (itself), but other cases can give us information. For example,
167 /// immediately after an "ashr X, 2", we know that the top 3 bits are all
168 /// equal to each other, so we return 3. For vectors, return the number of
169 /// sign bits for the vector element with the mininum number of known sign
171 unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL,
172 unsigned Depth = 0, AssumptionCache *AC = nullptr,
173 const Instruction *CxtI = nullptr,
174 const DominatorTree *DT = nullptr,
175 bool UseInstrInfo = true);
177 /// This function computes the integer multiple of Base that equals V. If
178 /// successful, it returns true and returns the multiple in Multiple. If
179 /// unsuccessful, it returns false. Also, if V can be simplified to an
180 /// integer, then the simplified V is returned in Val. Look through sext only
181 /// if LookThroughSExt=true.
182 bool ComputeMultiple(Value *V, unsigned Base, Value *&Multiple,
183 bool LookThroughSExt = false,
186 /// Map a call instruction to an intrinsic ID. Libcalls which have equivalent
187 /// intrinsics are treated as-if they were intrinsics.
188 Intrinsic::ID getIntrinsicForCallSite(ImmutableCallSite ICS,
189 const TargetLibraryInfo *TLI);
191 /// Return true if we can prove that the specified FP value is never equal to
193 bool CannotBeNegativeZero(const Value *V, const TargetLibraryInfo *TLI,
196 /// Return true if we can prove that the specified FP value is either NaN or
197 /// never less than -0.0.
204 bool CannotBeOrderedLessThanZero(const Value *V, const TargetLibraryInfo *TLI);
206 /// Return true if the floating-point scalar value is not an infinity or if
207 /// the floating-point vector value has no infinities. Return false if a value
208 /// could ever be infinity.
209 bool isKnownNeverInfinity(const Value *V, const TargetLibraryInfo *TLI,
212 /// Return true if the floating-point scalar value is not a NaN or if the
213 /// floating-point vector value has no NaN elements. Return false if a value
214 /// could ever be NaN.
215 bool isKnownNeverNaN(const Value *V, const TargetLibraryInfo *TLI,
218 /// Return true if we can prove that the specified FP value's sign bit is 0.
220 /// NaN --> true/false (depending on the NaN's sign bit)
225 bool SignBitMustBeZero(const Value *V, const TargetLibraryInfo *TLI);
227 /// If the specified value can be set by repeating the same byte in memory,
228 /// return the i8 value that it is represented with. This is true for all i8
229 /// values obviously, but is also true for i32 0, i32 -1, i16 0xF0F0, double
230 /// 0.0 etc. If the value can't be handled with a repeated byte store (e.g.
231 /// i16 0x1234), return null. If the value is entirely undef and padding,
233 Value *isBytewiseValue(Value *V, const DataLayout &DL);
235 /// Given an aggregate and an sequence of indices, see if the scalar value
236 /// indexed is already around as a register, for example if it were inserted
237 /// directly into the aggregate.
239 /// If InsertBefore is not null, this function will duplicate (modified)
240 /// insertvalues when a part of a nested struct is extracted.
241 Value *FindInsertedValue(Value *V,
242 ArrayRef<unsigned> idx_range,
243 Instruction *InsertBefore = nullptr);
245 /// Analyze the specified pointer to see if it can be expressed as a base
246 /// pointer plus a constant offset. Return the base and offset to the caller.
248 /// This is a wrapper around Value::stripAndAccumulateConstantOffsets that
249 /// creates and later unpacks the required APInt.
250 inline Value *GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
251 const DataLayout &DL,
252 bool AllowNonInbounds = true) {
253 APInt OffsetAPInt(DL.getIndexTypeSizeInBits(Ptr->getType()), 0);
255 Ptr->stripAndAccumulateConstantOffsets(DL, OffsetAPInt, AllowNonInbounds);
257 Offset = OffsetAPInt.getSExtValue();
261 GetPointerBaseWithConstantOffset(const Value *Ptr, int64_t &Offset,
262 const DataLayout &DL,
263 bool AllowNonInbounds = true) {
264 return GetPointerBaseWithConstantOffset(const_cast<Value *>(Ptr), Offset, DL,
268 /// Returns true if the GEP is based on a pointer to a string (array of
269 // \p CharSize integers) and is indexing into this string.
270 bool isGEPBasedOnPointerToString(const GEPOperator *GEP,
271 unsigned CharSize = 8);
273 /// Represents offset+length into a ConstantDataArray.
274 struct ConstantDataArraySlice {
275 /// ConstantDataArray pointer. nullptr indicates a zeroinitializer (a valid
276 /// initializer, it just doesn't fit the ConstantDataArray interface).
277 const ConstantDataArray *Array;
279 /// Slice starts at this Offset.
282 /// Length of the slice.
285 /// Moves the Offset and adjusts Length accordingly.
286 void move(uint64_t Delta) {
287 assert(Delta < Length);
292 /// Convenience accessor for elements in the slice.
293 uint64_t operator[](unsigned I) const {
294 return Array==nullptr ? 0 : Array->getElementAsInteger(I + Offset);
298 /// Returns true if the value \p V is a pointer into a ConstantDataArray.
299 /// If successful \p Slice will point to a ConstantDataArray info object
300 /// with an appropriate offset.
301 bool getConstantDataArrayInfo(const Value *V, ConstantDataArraySlice &Slice,
302 unsigned ElementSize, uint64_t Offset = 0);
304 /// This function computes the length of a null-terminated C string pointed to
305 /// by V. If successful, it returns true and returns the string in Str. If
306 /// unsuccessful, it returns false. This does not include the trailing null
307 /// character by default. If TrimAtNul is set to false, then this returns any
308 /// trailing null characters as well as any other characters that come after
310 bool getConstantStringInfo(const Value *V, StringRef &Str,
311 uint64_t Offset = 0, bool TrimAtNul = true);
313 /// If we can compute the length of the string pointed to by the specified
314 /// pointer, return 'len+1'. If we can't, return 0.
315 uint64_t GetStringLength(const Value *V, unsigned CharSize = 8);
317 /// This function returns call pointer argument that is considered the same by
318 /// aliasing rules. You CAN'T use it to replace one value with another. If
319 /// \p MustPreserveNullness is true, the call must preserve the nullness of
321 const Value *getArgumentAliasingToReturnedPointer(const CallBase *Call,
322 bool MustPreserveNullness);
324 getArgumentAliasingToReturnedPointer(CallBase *Call,
325 bool MustPreserveNullness) {
326 return const_cast<Value *>(getArgumentAliasingToReturnedPointer(
327 const_cast<const CallBase *>(Call), MustPreserveNullness));
330 /// {launder,strip}.invariant.group returns pointer that aliases its argument,
331 /// and it only captures pointer by returning it.
332 /// These intrinsics are not marked as nocapture, because returning is
333 /// considered as capture. The arguments are not marked as returned neither,
334 /// because it would make it useless. If \p MustPreserveNullness is true,
335 /// the intrinsic must preserve the nullness of the pointer.
336 bool isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(
337 const CallBase *Call, bool MustPreserveNullness);
339 /// This method strips off any GEP address adjustments and pointer casts from
340 /// the specified value, returning the original object being addressed. Note
341 /// that the returned value has pointer type if the specified value does. If
342 /// the MaxLookup value is non-zero, it limits the number of instructions to
344 Value *GetUnderlyingObject(Value *V, const DataLayout &DL,
345 unsigned MaxLookup = 6);
346 inline const Value *GetUnderlyingObject(const Value *V, const DataLayout &DL,
347 unsigned MaxLookup = 6) {
348 return GetUnderlyingObject(const_cast<Value *>(V), DL, MaxLookup);
351 /// This method is similar to GetUnderlyingObject except that it can
352 /// look through phi and select instructions and return multiple objects.
354 /// If LoopInfo is passed, loop phis are further analyzed. If a pointer
355 /// accesses different objects in each iteration, we don't look through the
356 /// phi node. E.g. consider this loop nest:
361 /// A[i][j] = A[i-1][j] * B[j]
364 /// This is transformed by Load-PRE to stash away A[i] for the next iteration
365 /// of the outer loop:
367 /// Curr = A[0]; // Prev_0
369 /// Prev = Curr; // Prev = PHI (Prev_0, Curr)
372 /// Curr[j] = Prev[j] * B[j]
376 /// Since A[i] and A[i-1] are independent pointers, getUnderlyingObjects
377 /// should not assume that Curr and Prev share the same underlying object thus
378 /// it shouldn't look through the phi above.
379 void GetUnderlyingObjects(const Value *V,
380 SmallVectorImpl<const Value *> &Objects,
381 const DataLayout &DL, LoopInfo *LI = nullptr,
382 unsigned MaxLookup = 6);
384 /// This is a wrapper around GetUnderlyingObjects and adds support for basic
385 /// ptrtoint+arithmetic+inttoptr sequences.
386 bool getUnderlyingObjectsForCodeGen(const Value *V,
387 SmallVectorImpl<Value *> &Objects,
388 const DataLayout &DL);
390 /// Return true if the only users of this pointer are lifetime markers.
391 bool onlyUsedByLifetimeMarkers(const Value *V);
393 /// Return true if speculation of the given load must be suppressed to avoid
394 /// ordering or interfering with an active sanitizer. If not suppressed,
395 /// dereferenceability and alignment must be proven separately. Note: This
396 /// is only needed for raw reasoning; if you use the interface below
397 /// (isSafeToSpeculativelyExecute), this is handled internally.
398 bool mustSuppressSpeculation(const LoadInst &LI);
400 /// Return true if the instruction does not have any effects besides
401 /// calculating the result and does not have undefined behavior.
403 /// This method never returns true for an instruction that returns true for
404 /// mayHaveSideEffects; however, this method also does some other checks in
405 /// addition. It checks for undefined behavior, like dividing by zero or
406 /// loading from an invalid pointer (but not for undefined results, like a
407 /// shift with a shift amount larger than the width of the result). It checks
408 /// for malloc and alloca because speculatively executing them might cause a
409 /// memory leak. It also returns false for instructions related to control
410 /// flow, specifically terminators and PHI nodes.
412 /// If the CtxI is specified this method performs context-sensitive analysis
413 /// and returns true if it is safe to execute the instruction immediately
416 /// If the CtxI is NOT specified this method only looks at the instruction
417 /// itself and its operands, so if this method returns true, it is safe to
418 /// move the instruction as long as the correct dominance relationships for
419 /// the operands and users hold.
421 /// This method can return true for instructions that read memory;
422 /// for such instructions, moving them may change the resulting value.
423 bool isSafeToSpeculativelyExecute(const Value *V,
424 const Instruction *CtxI = nullptr,
425 const DominatorTree *DT = nullptr);
427 /// Returns true if the result or effects of the given instructions \p I
428 /// depend on or influence global memory.
429 /// Memory dependence arises for example if the instruction reads from
430 /// memory or may produce effects or undefined behaviour. Memory dependent
431 /// instructions generally cannot be reorderd with respect to other memory
432 /// dependent instructions or moved into non-dominated basic blocks.
433 /// Instructions which just compute a value based on the values of their
434 /// operands are not memory dependent.
435 bool mayBeMemoryDependent(const Instruction &I);
437 /// Return true if it is an intrinsic that cannot be speculated but also
439 bool isAssumeLikeIntrinsic(const Instruction *I);
441 /// Return true if it is valid to use the assumptions provided by an
442 /// assume intrinsic, I, at the point in the control-flow identified by the
443 /// context instruction, CxtI.
444 bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI,
445 const DominatorTree *DT = nullptr);
447 enum class OverflowResult {
448 /// Always overflows in the direction of signed/unsigned min value.
450 /// Always overflows in the direction of signed/unsigned max value.
452 /// May or may not overflow.
458 OverflowResult computeOverflowForUnsignedMul(const Value *LHS,
460 const DataLayout &DL,
462 const Instruction *CxtI,
463 const DominatorTree *DT,
464 bool UseInstrInfo = true);
465 OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS,
466 const DataLayout &DL,
468 const Instruction *CxtI,
469 const DominatorTree *DT,
470 bool UseInstrInfo = true);
471 OverflowResult computeOverflowForUnsignedAdd(const Value *LHS,
473 const DataLayout &DL,
475 const Instruction *CxtI,
476 const DominatorTree *DT,
477 bool UseInstrInfo = true);
478 OverflowResult computeOverflowForSignedAdd(const Value *LHS, const Value *RHS,
479 const DataLayout &DL,
480 AssumptionCache *AC = nullptr,
481 const Instruction *CxtI = nullptr,
482 const DominatorTree *DT = nullptr);
483 /// This version also leverages the sign bit of Add if known.
484 OverflowResult computeOverflowForSignedAdd(const AddOperator *Add,
485 const DataLayout &DL,
486 AssumptionCache *AC = nullptr,
487 const Instruction *CxtI = nullptr,
488 const DominatorTree *DT = nullptr);
489 OverflowResult computeOverflowForUnsignedSub(const Value *LHS, const Value *RHS,
490 const DataLayout &DL,
492 const Instruction *CxtI,
493 const DominatorTree *DT);
494 OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS,
495 const DataLayout &DL,
497 const Instruction *CxtI,
498 const DominatorTree *DT);
500 /// Returns true if the arithmetic part of the \p WO 's result is
501 /// used only along the paths control dependent on the computation
502 /// not overflowing, \p WO being an <op>.with.overflow intrinsic.
503 bool isOverflowIntrinsicNoWrap(const WithOverflowInst *WO,
504 const DominatorTree &DT);
507 /// Determine the possible constant range of an integer or vector of integer
508 /// value. This is intended as a cheap, non-recursive check.
509 ConstantRange computeConstantRange(const Value *V, bool UseInstrInfo = true);
511 /// Return true if this function can prove that the instruction I will
512 /// always transfer execution to one of its successors (including the next
513 /// instruction that follows within a basic block). E.g. this is not
514 /// guaranteed for function calls that could loop infinitely.
516 /// In other words, this function returns false for instructions that may
517 /// transfer execution or fail to transfer execution in a way that is not
518 /// captured in the CFG nor in the sequence of instructions within a basic
521 /// Undefined behavior is assumed not to happen, so e.g. division is
522 /// guaranteed to transfer execution to the following instruction even
523 /// though division by zero might cause undefined behavior.
524 bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I);
526 /// Returns true if this block does not contain a potential implicit exit.
527 /// This is equivelent to saying that all instructions within the basic block
528 /// are guaranteed to transfer execution to their successor within the basic
529 /// block. This has the same assumptions w.r.t. undefined behavior as the
530 /// instruction variant of this function.
531 bool isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB);
533 /// Return true if this function can prove that the instruction I
534 /// is executed for every iteration of the loop L.
536 /// Note that this currently only considers the loop header.
537 bool isGuaranteedToExecuteForEveryIteration(const Instruction *I,
540 /// Return true if this function can prove that I is guaranteed to yield
541 /// full-poison (all bits poison) if at least one of its operands are
542 /// full-poison (all bits poison).
544 /// The exact rules for how poison propagates through instructions have
545 /// not been settled as of 2015-07-10, so this function is conservative
546 /// and only considers poison to be propagated in uncontroversial
547 /// cases. There is no attempt to track values that may be only partially
549 bool propagatesFullPoison(const Instruction *I);
551 /// Return either nullptr or an operand of I such that I will trigger
552 /// undefined behavior if I is executed and that operand has a full-poison
553 /// value (all bits poison).
554 const Value *getGuaranteedNonFullPoisonOp(const Instruction *I);
556 /// Return true if the given instruction must trigger undefined behavior.
557 /// when I is executed with any operands which appear in KnownPoison holding
558 /// a full-poison value at the point of execution.
559 bool mustTriggerUB(const Instruction *I,
560 const SmallSet<const Value *, 16>& KnownPoison);
562 /// Return true if this function can prove that if PoisonI is executed
563 /// and yields a full-poison value (all bits poison), then that will
564 /// trigger undefined behavior.
566 /// Note that this currently only considers the basic block that is
568 bool programUndefinedIfFullPoison(const Instruction *PoisonI);
570 /// Return true if this function can prove that V is never undef value
572 bool isGuaranteedNotToBeUndefOrPoison(const Value *V);
574 /// Specific patterns of select instructions we can match.
575 enum SelectPatternFlavor {
577 SPF_SMIN, /// Signed minimum
578 SPF_UMIN, /// Unsigned minimum
579 SPF_SMAX, /// Signed maximum
580 SPF_UMAX, /// Unsigned maximum
581 SPF_FMINNUM, /// Floating point minnum
582 SPF_FMAXNUM, /// Floating point maxnum
583 SPF_ABS, /// Absolute value
584 SPF_NABS /// Negated absolute value
587 /// Behavior when a floating point min/max is given one NaN and one
588 /// non-NaN as input.
589 enum SelectPatternNaNBehavior {
590 SPNB_NA = 0, /// NaN behavior not applicable.
591 SPNB_RETURNS_NAN, /// Given one NaN input, returns the NaN.
592 SPNB_RETURNS_OTHER, /// Given one NaN input, returns the non-NaN.
593 SPNB_RETURNS_ANY /// Given one NaN input, can return either (or
594 /// it has been determined that no operands can
598 struct SelectPatternResult {
599 SelectPatternFlavor Flavor;
600 SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is
601 /// SPF_FMINNUM or SPF_FMAXNUM.
602 bool Ordered; /// When implementing this min/max pattern as
603 /// fcmp; select, does the fcmp have to be
606 /// Return true if \p SPF is a min or a max pattern.
607 static bool isMinOrMax(SelectPatternFlavor SPF) {
608 return SPF != SPF_UNKNOWN && SPF != SPF_ABS && SPF != SPF_NABS;
612 /// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
613 /// and providing the out parameter results if we successfully match.
615 /// For ABS/NABS, LHS will be set to the input to the abs idiom. RHS will be
616 /// the negation instruction from the idiom.
618 /// If CastOp is not nullptr, also match MIN/MAX idioms where the type does
619 /// not match that of the original select. If this is the case, the cast
620 /// operation (one of Trunc,SExt,Zext) that must be done to transform the
621 /// type of LHS and RHS into the type of V is returned in CastOp.
624 /// %1 = icmp slt i32 %a, i32 4
625 /// %2 = sext i32 %a to i64
626 /// %3 = select i1 %1, i64 %2, i64 4
628 /// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt
630 SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
631 Instruction::CastOps *CastOp = nullptr,
634 inline SelectPatternResult
635 matchSelectPattern(const Value *V, const Value *&LHS, const Value *&RHS) {
636 Value *L = const_cast<Value *>(LHS);
637 Value *R = const_cast<Value *>(RHS);
638 auto Result = matchSelectPattern(const_cast<Value *>(V), L, R);
644 /// Determine the pattern that a select with the given compare as its
645 /// predicate and given values as its true/false operands would match.
646 SelectPatternResult matchDecomposedSelectPattern(
647 CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS,
648 Instruction::CastOps *CastOp = nullptr, unsigned Depth = 0);
650 /// Return the canonical comparison predicate for the specified
651 /// minimum/maximum flavor.
652 CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF,
653 bool Ordered = false);
655 /// Return the inverse minimum/maximum flavor of the specified flavor.
656 /// For example, signed minimum is the inverse of signed maximum.
657 SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF);
659 /// Return the canonical inverse comparison predicate for the specified
660 /// minimum/maximum flavor.
661 CmpInst::Predicate getInverseMinMaxPred(SelectPatternFlavor SPF);
663 /// Return true if RHS is known to be implied true by LHS. Return false if
664 /// RHS is known to be implied false by LHS. Otherwise, return None if no
665 /// implication can be made.
666 /// A & B must be i1 (boolean) values or a vector of such values. Note that
667 /// the truth table for implication is the same as <=u on i1 values (but not
668 /// <=s!). The truth table for both is:
673 Optional<bool> isImpliedCondition(const Value *LHS, const Value *RHS,
674 const DataLayout &DL, bool LHSIsTrue = true,
677 /// Return the boolean condition value in the context of the given instruction
678 /// if it is known based on dominating conditions.
679 Optional<bool> isImpliedByDomCondition(const Value *Cond,
680 const Instruction *ContextI,
681 const DataLayout &DL);
683 /// If Ptr1 is provably equal to Ptr2 plus a constant offset, return that
684 /// offset. For example, Ptr1 might be &A[42], and Ptr2 might be &A[40]. In
685 /// this case offset would be -8.
686 Optional<int64_t> isPointerOffset(const Value *Ptr1, const Value *Ptr2,
687 const DataLayout &DL);
688 } // end namespace llvm
690 #endif // LLVM_ANALYSIS_VALUETRACKING_H