LLVM 20.0.0git
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
19#include "llvm/IR/Constants.h"
20#include "llvm/IR/DataLayout.h"
21#include "llvm/IR/FMF.h"
23#include "llvm/IR/InstrTypes.h"
24#include "llvm/IR/Intrinsics.h"
25#include <cassert>
26#include <cstdint>
27
28namespace llvm {
29
30class Operator;
31class AddOperator;
32class AssumptionCache;
33class DominatorTree;
34class GEPOperator;
35class WithOverflowInst;
36struct KnownBits;
37class Loop;
38class LoopInfo;
39class MDNode;
40class StringRef;
41class TargetLibraryInfo;
42template <typename T> class ArrayRef;
43
44constexpr unsigned MaxAnalysisRecursionDepth = 6;
45
46/// Determine which bits of V are known to be either zero or one and return
47/// them in the KnownZero/KnownOne bit sets.
48///
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.
54void computeKnownBits(const Value *V, KnownBits &Known, const DataLayout &DL,
55 unsigned Depth = 0, AssumptionCache *AC = nullptr,
56 const Instruction *CxtI = nullptr,
57 const DominatorTree *DT = nullptr,
58 bool UseInstrInfo = true);
59
60/// Returns the known bits rather than passing by reference.
62 unsigned Depth = 0, AssumptionCache *AC = nullptr,
63 const Instruction *CxtI = nullptr,
64 const DominatorTree *DT = nullptr,
65 bool UseInstrInfo = true);
66
67/// Returns the known bits rather than passing by reference.
68KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts,
69 const DataLayout &DL, unsigned Depth = 0,
70 AssumptionCache *AC = nullptr,
71 const Instruction *CxtI = nullptr,
72 const DominatorTree *DT = nullptr,
73 bool UseInstrInfo = true);
74
75KnownBits computeKnownBits(const Value *V, const APInt &DemandedElts,
76 unsigned Depth, const SimplifyQuery &Q);
77
78KnownBits computeKnownBits(const Value *V, unsigned Depth,
79 const SimplifyQuery &Q);
80
81void computeKnownBits(const Value *V, KnownBits &Known, unsigned Depth,
82 const SimplifyQuery &Q);
83
84/// Compute known bits from the range metadata.
85/// \p KnownZero the set of bits that are known to be zero
86/// \p KnownOne the set of bits that are known to be one
87void computeKnownBitsFromRangeMetadata(const MDNode &Ranges, KnownBits &Known);
88
89/// Merge bits known from context-dependent facts into Known.
90void computeKnownBitsFromContext(const Value *V, KnownBits &Known,
91 unsigned Depth, const SimplifyQuery &Q);
92
93/// Using KnownBits LHS/RHS produce the known bits for logic op (and/xor/or).
95 const KnownBits &KnownLHS,
96 const KnownBits &KnownRHS,
97 unsigned Depth, const SimplifyQuery &SQ);
98
99/// Adjust \p Known for the given select \p Arm to include information from the
100/// select \p Cond.
102 bool Invert, unsigned Depth,
103 const SimplifyQuery &Q);
104
105/// Return true if LHS and RHS have no common bits set.
107 const WithCache<const Value *> &RHSCache,
108 const SimplifyQuery &SQ);
109
110/// Return true if the given value is known to have exactly one bit set when
111/// defined. For vectors return true if every element is known to be a power
112/// of two when defined. Supports values with integer or pointer type and
113/// vectors of integers. If 'OrZero' is set, then return true if the given
114/// value is either a power of two or zero.
115bool isKnownToBeAPowerOfTwo(const Value *V, const DataLayout &DL,
116 bool OrZero = false, unsigned Depth = 0,
117 AssumptionCache *AC = nullptr,
118 const Instruction *CxtI = nullptr,
119 const DominatorTree *DT = nullptr,
120 bool UseInstrInfo = true);
121
123
125
126/// Return true if the given value is known to be non-zero when defined. For
127/// vectors, return true if every element is known to be non-zero when
128/// defined. For pointers, if the context instruction and dominator tree are
129/// specified, perform context-sensitive analysis and return true if the
130/// pointer couldn't possibly be null at the specified instruction.
131/// Supports values with integer or pointer type and vectors of integers.
132bool isKnownNonZero(const Value *V, const SimplifyQuery &Q, unsigned Depth = 0);
133
134/// Return true if the two given values are negation.
135/// Currently can recoginze Value pair:
136/// 1: <X, Y> if X = sub (0, Y) or Y = sub (0, X)
137/// 2: <X, Y> if X = sub (A, B) and Y = sub (B, A)
138bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW = false,
139 bool AllowPoison = true);
140
141/// Return true iff:
142/// 1. X is poison implies Y is poison.
143/// 2. X is true implies Y is false.
144/// 3. X is false implies Y is true.
145/// Otherwise, return false.
146bool isKnownInversion(const Value *X, const Value *Y);
147
148/// Returns true if the give value is known to be non-negative.
149bool isKnownNonNegative(const Value *V, const SimplifyQuery &SQ,
150 unsigned Depth = 0);
151
152/// Returns true if the given value is known be positive (i.e. non-negative
153/// and non-zero).
154bool isKnownPositive(const Value *V, const SimplifyQuery &SQ,
155 unsigned Depth = 0);
156
157/// Returns true if the given value is known be negative (i.e. non-positive
158/// and non-zero).
159bool isKnownNegative(const Value *V, const SimplifyQuery &DL,
160 unsigned Depth = 0);
161
162/// Return true if the given values are known to be non-equal when defined.
163/// Supports scalar integer types only.
164bool isKnownNonEqual(const Value *V1, const Value *V2, const DataLayout &DL,
165 AssumptionCache *AC = nullptr,
166 const Instruction *CxtI = nullptr,
167 const DominatorTree *DT = nullptr,
168 bool UseInstrInfo = true);
169
170/// Return true if 'V & Mask' is known to be zero. We use this predicate to
171/// simplify operations downstream. Mask is known to be zero for bits that V
172/// cannot have.
173///
174/// This function is defined on values with integer type, values with pointer
175/// type, and vectors of integers. In the case
176/// where V is a vector, the mask, known zero, and known one values are the
177/// same width as the vector element, and the bit is set only if it is true
178/// for all of the elements in the vector.
179bool MaskedValueIsZero(const Value *V, const APInt &Mask,
180 const SimplifyQuery &DL, unsigned Depth = 0);
181
182/// Return the number of times the sign bit of the register is replicated into
183/// the other bits. We know that at least 1 bit is always equal to the sign
184/// bit (itself), but other cases can give us information. For example,
185/// immediately after an "ashr X, 2", we know that the top 3 bits are all
186/// equal to each other, so we return 3. For vectors, return the number of
187/// sign bits for the vector element with the mininum number of known sign
188/// bits.
189unsigned ComputeNumSignBits(const Value *Op, const DataLayout &DL,
190 unsigned Depth = 0, AssumptionCache *AC = nullptr,
191 const Instruction *CxtI = nullptr,
192 const DominatorTree *DT = nullptr,
193 bool UseInstrInfo = true);
194
195/// Get the upper bound on bit size for this Value \p Op as a signed integer.
196/// i.e. x == sext(trunc(x to MaxSignificantBits) to bitwidth(x)).
197/// Similar to the APInt::getSignificantBits function.
198unsigned ComputeMaxSignificantBits(const Value *Op, const DataLayout &DL,
199 unsigned Depth = 0,
200 AssumptionCache *AC = nullptr,
201 const Instruction *CxtI = nullptr,
202 const DominatorTree *DT = nullptr);
203
204/// Map a call instruction to an intrinsic ID. Libcalls which have equivalent
205/// intrinsics are treated as-if they were intrinsics.
207 const TargetLibraryInfo *TLI);
208
209/// Given an exploded icmp instruction, return true if the comparison only
210/// checks the sign bit. If it only checks the sign bit, set TrueIfSigned if
211/// the result of the comparison is true when the input value is signed.
213 bool &TrueIfSigned);
214
215/// Returns a pair of values, which if passed to llvm.is.fpclass, returns the
216/// same result as an fcmp with the given operands.
217///
218/// If \p LookThroughSrc is true, consider the input value when computing the
219/// mask.
220///
221/// If \p LookThroughSrc is false, ignore the source value (i.e. the first pair
222/// element will always be LHS.
223std::pair<Value *, FPClassTest> fcmpToClassTest(CmpInst::Predicate Pred,
224 const Function &F, Value *LHS,
225 Value *RHS,
226 bool LookThroughSrc = true);
227std::pair<Value *, FPClassTest> fcmpToClassTest(CmpInst::Predicate Pred,
228 const Function &F, Value *LHS,
229 const APFloat *ConstRHS,
230 bool LookThroughSrc = true);
231
232/// Compute the possible floating-point classes that \p LHS could be based on
233/// fcmp \Pred \p LHS, \p RHS.
234///
235/// \returns { TestedValue, ClassesIfTrue, ClassesIfFalse }
236///
237/// If the compare returns an exact class test, ClassesIfTrue == ~ClassesIfFalse
238///
239/// This is a less exact version of fcmpToClassTest (e.g. fcmpToClassTest will
240/// only succeed for a test of x > 0 implies positive, but not x > 1).
241///
242/// If \p LookThroughSrc is true, consider the input value when computing the
243/// mask. This may look through sign bit operations.
244///
245/// If \p LookThroughSrc is false, ignore the source value (i.e. the first pair
246/// element will always be LHS.
247///
248std::tuple<Value *, FPClassTest, FPClassTest>
250 Value *RHS, bool LookThroughSrc = true);
251std::tuple<Value *, FPClassTest, FPClassTest>
253 FPClassTest RHS, bool LookThroughSrc = true);
254std::tuple<Value *, FPClassTest, FPClassTest>
256 const APFloat &RHS, bool LookThroughSrc = true);
257
259 /// Floating-point classes the value could be one of.
261
262 /// std::nullopt if the sign bit is unknown, true if the sign bit is
263 /// definitely set or false if the sign bit is definitely unset.
264 std::optional<bool> SignBit;
265
267 return KnownFPClasses == Other.KnownFPClasses && SignBit == Other.SignBit;
268 }
269
270 /// Return true if it's known this can never be one of the mask entries.
271 bool isKnownNever(FPClassTest Mask) const {
272 return (KnownFPClasses & Mask) == fcNone;
273 }
274
275 bool isKnownAlways(FPClassTest Mask) const { return isKnownNever(~Mask); }
276
277 bool isUnknown() const {
278 return KnownFPClasses == fcAllFlags && !SignBit;
279 }
280
281 /// Return true if it's known this can never be a nan.
282 bool isKnownNeverNaN() const {
283 return isKnownNever(fcNan);
284 }
285
286 /// Return true if it's known this must always be a nan.
287 bool isKnownAlwaysNaN() const { return isKnownAlways(fcNan); }
288
289 /// Return true if it's known this can never be an infinity.
290 bool isKnownNeverInfinity() const {
291 return isKnownNever(fcInf);
292 }
293
294 /// Return true if it's known this can never be +infinity.
296 return isKnownNever(fcPosInf);
297 }
298
299 /// Return true if it's known this can never be -infinity.
301 return isKnownNever(fcNegInf);
302 }
303
304 /// Return true if it's known this can never be a subnormal
307 }
308
309 /// Return true if it's known this can never be a positive subnormal
312 }
313
314 /// Return true if it's known this can never be a negative subnormal
317 }
318
319 /// Return true if it's known this can never be a zero. This means a literal
320 /// [+-]0, and does not include denormal inputs implicitly treated as [+-]0.
321 bool isKnownNeverZero() const {
322 return isKnownNever(fcZero);
323 }
324
325 /// Return true if it's known this can never be a literal positive zero.
326 bool isKnownNeverPosZero() const {
327 return isKnownNever(fcPosZero);
328 }
329
330 /// Return true if it's known this can never be a negative zero. This means a
331 /// literal -0 and does not include denormal inputs implicitly treated as -0.
332 bool isKnownNeverNegZero() const {
333 return isKnownNever(fcNegZero);
334 }
335
336 /// Return true if it's know this can never be interpreted as a zero. This
337 /// extends isKnownNeverZero to cover the case where the assumed
338 /// floating-point mode for the function interprets denormals as zero.
339 bool isKnownNeverLogicalZero(const Function &F, Type *Ty) const;
340
341 /// Return true if it's know this can never be interpreted as a negative zero.
342 bool isKnownNeverLogicalNegZero(const Function &F, Type *Ty) const;
343
344 /// Return true if it's know this can never be interpreted as a positive zero.
345 bool isKnownNeverLogicalPosZero(const Function &F, Type *Ty) const;
346
351
352 /// Return true if we can prove that the analyzed floating-point value is
353 /// either NaN or never less than -0.0.
354 ///
355 /// NaN --> true
356 /// +0 --> true
357 /// -0 --> true
358 /// x > +0 --> true
359 /// x < -0 --> false
362 }
363
364 /// Return true if we can prove that the analyzed floating-point value is
365 /// either NaN or never greater than -0.0.
366 /// NaN --> true
367 /// +0 --> true
368 /// -0 --> true
369 /// x > +0 --> false
370 /// x < -0 --> true
373 }
374
376 KnownFPClasses = KnownFPClasses | RHS.KnownFPClasses;
377
378 if (SignBit != RHS.SignBit)
379 SignBit = std::nullopt;
380 return *this;
381 }
382
383 void knownNot(FPClassTest RuleOut) {
384 KnownFPClasses = KnownFPClasses & ~RuleOut;
385 if (isKnownNever(fcNan) && !SignBit) {
387 SignBit = false;
388 else if (isKnownNever(fcPositive))
389 SignBit = true;
390 }
391 }
392
393 void fneg() {
395 if (SignBit)
396 SignBit = !*SignBit;
397 }
398
399 void fabs() {
402
405
408
411
413 }
414
415 /// Return true if the sign bit must be 0, ignoring the sign of nans.
416 bool signBitIsZeroOrNaN() const {
417 return isKnownNever(fcNegative);
418 }
419
420 /// Assume the sign bit is zero.
423 SignBit = false;
424 }
425
426 /// Assume the sign bit is one.
429 SignBit = true;
430 }
431
432 void copysign(const KnownFPClass &Sign) {
433 // Don't know anything about the sign of the source. Expand the possible set
434 // to its opposite sign pair.
441 if (KnownFPClasses & fcInf)
443
444 // Sign bit is exactly preserved even for nans.
445 SignBit = Sign.SignBit;
446
447 // Clear sign bits based on the input sign mask.
448 if (Sign.isKnownNever(fcPositive | fcNan) || (SignBit && *SignBit))
450 if (Sign.isKnownNever(fcNegative | fcNan) || (SignBit && !*SignBit))
452 }
453
454 // Propagate knowledge that a non-NaN source implies the result can also not
455 // be a NaN. For unconstrained operations, signaling nans are not guaranteed
456 // to be quieted but cannot be introduced.
457 void propagateNaN(const KnownFPClass &Src, bool PreserveSign = false) {
458 if (Src.isKnownNever(fcNan)) {
460 if (PreserveSign)
461 SignBit = Src.SignBit;
462 } else if (Src.isKnownNever(fcSNan))
464 }
465
466 /// Propagate knowledge from a source value that could be a denormal or
467 /// zero. We have to be conservative since output flushing is not guaranteed,
468 /// so known-never-zero may not hold.
469 ///
470 /// This assumes a copy-like operation and will replace any currently known
471 /// information.
472 void propagateDenormal(const KnownFPClass &Src, const Function &F, Type *Ty);
473
474 /// Report known classes if \p Src is evaluated through a potentially
475 /// canonicalizing operation. We can assume signaling nans will not be
476 /// introduced, but cannot assume a denormal will be flushed under FTZ/DAZ.
477 ///
478 /// This assumes a copy-like operation and will replace any currently known
479 /// information.
480 void propagateCanonicalizingSrc(const KnownFPClass &Src, const Function &F,
481 Type *Ty);
482
483 void resetAll() { *this = KnownFPClass(); }
484};
485
487 LHS |= RHS;
488 return LHS;
489}
490
492 RHS |= LHS;
493 return std::move(RHS);
494}
495
496/// Determine which floating-point classes are valid for \p V, and return them
497/// in KnownFPClass bit sets.
498///
499/// This function is defined on values with floating-point type, values vectors
500/// of floating-point type, and arrays of floating-point type.
501
502/// \p InterestedClasses is a compile time optimization hint for which floating
503/// point classes should be queried. Queries not specified in \p
504/// InterestedClasses should be reliable if they are determined during the
505/// query.
506KnownFPClass computeKnownFPClass(const Value *V, const APInt &DemandedElts,
507 FPClassTest InterestedClasses, unsigned Depth,
508 const SimplifyQuery &SQ);
509
510KnownFPClass computeKnownFPClass(const Value *V, FPClassTest InterestedClasses,
511 unsigned Depth, const SimplifyQuery &SQ);
512
514 const Value *V, const DataLayout &DL,
515 FPClassTest InterestedClasses = fcAllFlags, unsigned Depth = 0,
516 const TargetLibraryInfo *TLI = nullptr, AssumptionCache *AC = nullptr,
517 const Instruction *CxtI = nullptr, const DominatorTree *DT = nullptr,
518 bool UseInstrInfo = true) {
519 return computeKnownFPClass(
520 V, InterestedClasses, Depth,
521 SimplifyQuery(DL, TLI, DT, AC, CxtI, UseInstrInfo));
522}
523
524/// Wrapper to account for known fast math flags at the use instruction.
525inline KnownFPClass
526computeKnownFPClass(const Value *V, const APInt &DemandedElts,
527 FastMathFlags FMF, FPClassTest InterestedClasses,
528 unsigned Depth, const SimplifyQuery &SQ) {
529 if (FMF.noNaNs())
530 InterestedClasses &= ~fcNan;
531 if (FMF.noInfs())
532 InterestedClasses &= ~fcInf;
533
534 KnownFPClass Result =
535 computeKnownFPClass(V, DemandedElts, InterestedClasses, Depth, SQ);
536
537 if (FMF.noNaNs())
538 Result.KnownFPClasses &= ~fcNan;
539 if (FMF.noInfs())
540 Result.KnownFPClasses &= ~fcInf;
541 return Result;
542}
543
545 FPClassTest InterestedClasses,
546 unsigned Depth,
547 const SimplifyQuery &SQ) {
548 auto *FVTy = dyn_cast<FixedVectorType>(V->getType());
549 APInt DemandedElts =
550 FVTy ? APInt::getAllOnes(FVTy->getNumElements()) : APInt(1, 1);
551 return computeKnownFPClass(V, DemandedElts, FMF, InterestedClasses, Depth,
552 SQ);
553}
554
555/// Return true if we can prove that the specified FP value is never equal to
556/// -0.0. Users should use caution when considering PreserveSign
557/// denormal-fp-math.
558inline bool cannotBeNegativeZero(const Value *V, unsigned Depth,
559 const SimplifyQuery &SQ) {
561 return Known.isKnownNeverNegZero();
562}
563
564/// Return true if we can prove that the specified FP value is either NaN or
565/// never less than -0.0.
566///
567/// NaN --> true
568/// +0 --> true
569/// -0 --> true
570/// x > +0 --> true
571/// x < -0 --> false
572inline bool cannotBeOrderedLessThanZero(const Value *V, unsigned Depth,
573 const SimplifyQuery &SQ) {
574 KnownFPClass Known =
576 return Known.cannotBeOrderedLessThanZero();
577}
578
579/// Return true if the floating-point scalar value is not an infinity or if
580/// the floating-point vector value has no infinities. Return false if a value
581/// could ever be infinity.
582inline bool isKnownNeverInfinity(const Value *V, unsigned Depth,
583 const SimplifyQuery &SQ) {
585 return Known.isKnownNeverInfinity();
586}
587
588/// Return true if the floating-point value can never contain a NaN or infinity.
589inline bool isKnownNeverInfOrNaN(const Value *V, unsigned Depth,
590 const SimplifyQuery &SQ) {
592 return Known.isKnownNeverNaN() && Known.isKnownNeverInfinity();
593}
594
595/// Return true if the floating-point scalar value is not a NaN or if the
596/// floating-point vector value has no NaN elements. Return false if a value
597/// could ever be NaN.
598inline bool isKnownNeverNaN(const Value *V, unsigned Depth,
599 const SimplifyQuery &SQ) {
601 return Known.isKnownNeverNaN();
602}
603
604/// Return false if we can prove that the specified FP value's sign bit is 0.
605/// Return true if we can prove that the specified FP value's sign bit is 1.
606/// Otherwise return std::nullopt.
607inline std::optional<bool> computeKnownFPSignBit(const Value *V, unsigned Depth,
608 const SimplifyQuery &SQ) {
610 return Known.SignBit;
611}
612
613/// If the specified value can be set by repeating the same byte in memory,
614/// return the i8 value that it is represented with. This is true for all i8
615/// values obviously, but is also true for i32 0, i32 -1, i16 0xF0F0, double
616/// 0.0 etc. If the value can't be handled with a repeated byte store (e.g.
617/// i16 0x1234), return null. If the value is entirely undef and padding,
618/// return undef.
619Value *isBytewiseValue(Value *V, const DataLayout &DL);
620
621/// Given an aggregate and an sequence of indices, see if the scalar value
622/// indexed is already around as a register, for example if it were inserted
623/// directly into the aggregate.
624///
625/// If InsertBefore is not empty, this function will duplicate (modified)
626/// insertvalues when a part of a nested struct is extracted.
627Value *FindInsertedValue(
628 Value *V, ArrayRef<unsigned> idx_range,
629 std::optional<BasicBlock::iterator> InsertBefore = std::nullopt);
630
631/// Analyze the specified pointer to see if it can be expressed as a base
632/// pointer plus a constant offset. Return the base and offset to the caller.
633///
634/// This is a wrapper around Value::stripAndAccumulateConstantOffsets that
635/// creates and later unpacks the required APInt.
637 const DataLayout &DL,
638 bool AllowNonInbounds = true) {
639 APInt OffsetAPInt(DL.getIndexTypeSizeInBits(Ptr->getType()), 0);
640 Value *Base =
641 Ptr->stripAndAccumulateConstantOffsets(DL, OffsetAPInt, AllowNonInbounds);
642
643 Offset = OffsetAPInt.getSExtValue();
644 return Base;
645}
646inline const Value *
648 const DataLayout &DL,
649 bool AllowNonInbounds = true) {
650 return GetPointerBaseWithConstantOffset(const_cast<Value *>(Ptr), Offset, DL,
651 AllowNonInbounds);
652}
653
654/// Returns true if the GEP is based on a pointer to a string (array of
655// \p CharSize integers) and is indexing into this string.
656bool isGEPBasedOnPointerToString(const GEPOperator *GEP, unsigned CharSize = 8);
657
658/// Represents offset+length into a ConstantDataArray.
660 /// ConstantDataArray pointer. nullptr indicates a zeroinitializer (a valid
661 /// initializer, it just doesn't fit the ConstantDataArray interface).
663
664 /// Slice starts at this Offset.
666
667 /// Length of the slice.
669
670 /// Moves the Offset and adjusts Length accordingly.
671 void move(uint64_t Delta) {
672 assert(Delta < Length);
673 Offset += Delta;
674 Length -= Delta;
675 }
676
677 /// Convenience accessor for elements in the slice.
678 uint64_t operator[](unsigned I) const {
679 return Array == nullptr ? 0 : Array->getElementAsInteger(I + Offset);
680 }
681};
682
683/// Returns true if the value \p V is a pointer into a ConstantDataArray.
684/// If successful \p Slice will point to a ConstantDataArray info object
685/// with an appropriate offset.
686bool getConstantDataArrayInfo(const Value *V, ConstantDataArraySlice &Slice,
687 unsigned ElementSize, uint64_t Offset = 0);
688
689/// This function computes the length of a null-terminated C string pointed to
690/// by V. If successful, it returns true and returns the string in Str. If
691/// unsuccessful, it returns false. This does not include the trailing null
692/// character by default. If TrimAtNul is set to false, then this returns any
693/// trailing null characters as well as any other characters that come after
694/// it.
695bool getConstantStringInfo(const Value *V, StringRef &Str,
696 bool TrimAtNul = true);
697
698/// If we can compute the length of the string pointed to by the specified
699/// pointer, return 'len+1'. If we can't, return 0.
700uint64_t GetStringLength(const Value *V, unsigned CharSize = 8);
701
702/// This function returns call pointer argument that is considered the same by
703/// aliasing rules. You CAN'T use it to replace one value with another. If
704/// \p MustPreserveNullness is true, the call must preserve the nullness of
705/// the pointer.
706const Value *getArgumentAliasingToReturnedPointer(const CallBase *Call,
707 bool MustPreserveNullness);
709 bool MustPreserveNullness) {
710 return const_cast<Value *>(getArgumentAliasingToReturnedPointer(
711 const_cast<const CallBase *>(Call), MustPreserveNullness));
712}
713
714/// {launder,strip}.invariant.group returns pointer that aliases its argument,
715/// and it only captures pointer by returning it.
716/// These intrinsics are not marked as nocapture, because returning is
717/// considered as capture. The arguments are not marked as returned neither,
718/// because it would make it useless. If \p MustPreserveNullness is true,
719/// the intrinsic must preserve the nullness of the pointer.
721 const CallBase *Call, bool MustPreserveNullness);
722
723/// This method strips off any GEP address adjustments, pointer casts
724/// or `llvm.threadlocal.address` from the specified value \p V, returning the
725/// original object being addressed. Note that the returned value has pointer
726/// type if the specified value does. If the \p MaxLookup value is non-zero, it
727/// limits the number of instructions to be stripped off.
728const Value *getUnderlyingObject(const Value *V, unsigned MaxLookup = 6);
729inline Value *getUnderlyingObject(Value *V, unsigned MaxLookup = 6) {
730 // Force const to avoid infinite recursion.
731 const Value *VConst = V;
732 return const_cast<Value *>(getUnderlyingObject(VConst, MaxLookup));
733}
734
735/// Like getUnderlyingObject(), but will try harder to find a single underlying
736/// object. In particular, this function also looks through selects and phis.
737const Value *getUnderlyingObjectAggressive(const Value *V);
738
739/// This method is similar to getUnderlyingObject except that it can
740/// look through phi and select instructions and return multiple objects.
741///
742/// If LoopInfo is passed, loop phis are further analyzed. If a pointer
743/// accesses different objects in each iteration, we don't look through the
744/// phi node. E.g. consider this loop nest:
745///
746/// int **A;
747/// for (i)
748/// for (j) {
749/// A[i][j] = A[i-1][j] * B[j]
750/// }
751///
752/// This is transformed by Load-PRE to stash away A[i] for the next iteration
753/// of the outer loop:
754///
755/// Curr = A[0]; // Prev_0
756/// for (i: 1..N) {
757/// Prev = Curr; // Prev = PHI (Prev_0, Curr)
758/// Curr = A[i];
759/// for (j: 0..N) {
760/// Curr[j] = Prev[j] * B[j]
761/// }
762/// }
763///
764/// Since A[i] and A[i-1] are independent pointers, getUnderlyingObjects
765/// should not assume that Curr and Prev share the same underlying object thus
766/// it shouldn't look through the phi above.
767void getUnderlyingObjects(const Value *V,
768 SmallVectorImpl<const Value *> &Objects,
769 const LoopInfo *LI = nullptr, unsigned MaxLookup = 6);
770
771/// This is a wrapper around getUnderlyingObjects and adds support for basic
772/// ptrtoint+arithmetic+inttoptr sequences.
773bool getUnderlyingObjectsForCodeGen(const Value *V,
774 SmallVectorImpl<Value *> &Objects);
775
776/// Returns unique alloca where the value comes from, or nullptr.
777/// If OffsetZero is true check that V points to the begining of the alloca.
778AllocaInst *findAllocaForValue(Value *V, bool OffsetZero = false);
779inline const AllocaInst *findAllocaForValue(const Value *V,
780 bool OffsetZero = false) {
781 return findAllocaForValue(const_cast<Value *>(V), OffsetZero);
782}
783
784/// Return true if the only users of this pointer are lifetime markers.
785bool onlyUsedByLifetimeMarkers(const Value *V);
786
787/// Return true if the only users of this pointer are lifetime markers or
788/// droppable instructions.
790
791/// Return true if the instruction does not have any effects besides
792/// calculating the result and does not have undefined behavior.
793///
794/// This method never returns true for an instruction that returns true for
795/// mayHaveSideEffects; however, this method also does some other checks in
796/// addition. It checks for undefined behavior, like dividing by zero or
797/// loading from an invalid pointer (but not for undefined results, like a
798/// shift with a shift amount larger than the width of the result). It checks
799/// for malloc and alloca because speculatively executing them might cause a
800/// memory leak. It also returns false for instructions related to control
801/// flow, specifically terminators and PHI nodes.
802///
803/// If the CtxI is specified this method performs context-sensitive analysis
804/// and returns true if it is safe to execute the instruction immediately
805/// before the CtxI.
806///
807/// If the CtxI is NOT specified this method only looks at the instruction
808/// itself and its operands, so if this method returns true, it is safe to
809/// move the instruction as long as the correct dominance relationships for
810/// the operands and users hold.
811///
812/// This method can return true for instructions that read memory;
813/// for such instructions, moving them may change the resulting value.
814bool isSafeToSpeculativelyExecute(const Instruction *I,
815 const Instruction *CtxI = nullptr,
816 AssumptionCache *AC = nullptr,
817 const DominatorTree *DT = nullptr,
818 const TargetLibraryInfo *TLI = nullptr,
819 bool UseVariableInfo = true);
820
823 AssumptionCache *AC = nullptr,
824 const DominatorTree *DT = nullptr,
825 const TargetLibraryInfo *TLI = nullptr,
826 bool UseVariableInfo = true) {
827 // Take an iterator, and unwrap it into an Instruction *.
828 return isSafeToSpeculativelyExecute(I, &*CtxI, AC, DT, TLI, UseVariableInfo);
829}
830
831/// Don't use information from its non-constant operands. This helper is used
832/// when its operands are going to be replaced.
833inline bool
835 return isSafeToSpeculativelyExecute(I, nullptr, nullptr, nullptr, nullptr,
836 /*UseVariableInfo=*/false);
837}
838
839/// This returns the same result as isSafeToSpeculativelyExecute if Opcode is
840/// the actual opcode of Inst. If the provided and actual opcode differ, the
841/// function (virtually) overrides the opcode of Inst with the provided
842/// Opcode. There are come constraints in this case:
843/// * If Opcode has a fixed number of operands (eg, as binary operators do),
844/// then Inst has to have at least as many leading operands. The function
845/// will ignore all trailing operands beyond that number.
846/// * If Opcode allows for an arbitrary number of operands (eg, as CallInsts
847/// do), then all operands are considered.
848/// * The virtual instruction has to satisfy all typing rules of the provided
849/// Opcode.
850/// * This function is pessimistic in the following sense: If one actually
851/// materialized the virtual instruction, then isSafeToSpeculativelyExecute
852/// may say that the materialized instruction is speculatable whereas this
853/// function may have said that the instruction wouldn't be speculatable.
854/// This behavior is a shortcoming in the current implementation and not
855/// intentional.
857 unsigned Opcode, const Instruction *Inst, const Instruction *CtxI = nullptr,
858 AssumptionCache *AC = nullptr, const DominatorTree *DT = nullptr,
859 const TargetLibraryInfo *TLI = nullptr, bool UseVariableInfo = true);
860
861/// Returns true if the result or effects of the given instructions \p I
862/// depend values not reachable through the def use graph.
863/// * Memory dependence arises for example if the instruction reads from
864/// memory or may produce effects or undefined behaviour. Memory dependent
865/// instructions generally cannot be reorderd with respect to other memory
866/// dependent instructions.
867/// * Control dependence arises for example if the instruction may fault
868/// if lifted above a throwing call or infinite loop.
869bool mayHaveNonDefUseDependency(const Instruction &I);
870
871/// Return true if it is an intrinsic that cannot be speculated but also
872/// cannot trap.
873bool isAssumeLikeIntrinsic(const Instruction *I);
874
875/// Return true if it is valid to use the assumptions provided by an
876/// assume intrinsic, I, at the point in the control-flow identified by the
877/// context instruction, CxtI. By default, ephemeral values of the assumption
878/// are treated as an invalid context, to prevent the assumption from being used
879/// to optimize away its argument. If the caller can ensure that this won't
880/// happen, it can call with AllowEphemerals set to true to get more valid
881/// assumptions.
882bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI,
883 const DominatorTree *DT = nullptr,
884 bool AllowEphemerals = false);
885
886enum class OverflowResult {
887 /// Always overflows in the direction of signed/unsigned min value.
889 /// Always overflows in the direction of signed/unsigned max value.
891 /// May or may not overflow.
893 /// Never overflows.
895};
896
897OverflowResult computeOverflowForUnsignedMul(const Value *LHS, const Value *RHS,
898 const SimplifyQuery &SQ,
899 bool IsNSW = false);
900OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS,
901 const SimplifyQuery &SQ);
903computeOverflowForUnsignedAdd(const WithCache<const Value *> &LHS,
904 const WithCache<const Value *> &RHS,
905 const SimplifyQuery &SQ);
906OverflowResult computeOverflowForSignedAdd(const WithCache<const Value *> &LHS,
907 const WithCache<const Value *> &RHS,
908 const SimplifyQuery &SQ);
909/// This version also leverages the sign bit of Add if known.
911 const SimplifyQuery &SQ);
912OverflowResult computeOverflowForUnsignedSub(const Value *LHS, const Value *RHS,
913 const SimplifyQuery &SQ);
914OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS,
915 const SimplifyQuery &SQ);
916
917/// Returns true if the arithmetic part of the \p WO 's result is
918/// used only along the paths control dependent on the computation
919/// not overflowing, \p WO being an <op>.with.overflow intrinsic.
920bool isOverflowIntrinsicNoWrap(const WithOverflowInst *WO,
921 const DominatorTree &DT);
922
923/// Determine the possible constant range of vscale with the given bit width,
924/// based on the vscale_range function attribute.
925ConstantRange getVScaleRange(const Function *F, unsigned BitWidth);
926
927/// Determine the possible constant range of an integer or vector of integer
928/// value. This is intended as a cheap, non-recursive check.
929ConstantRange computeConstantRange(const Value *V, bool ForSigned,
930 bool UseInstrInfo = true,
931 AssumptionCache *AC = nullptr,
932 const Instruction *CtxI = nullptr,
933 const DominatorTree *DT = nullptr,
934 unsigned Depth = 0);
935
936/// Combine constant ranges from computeConstantRange() and computeKnownBits().
937ConstantRange
938computeConstantRangeIncludingKnownBits(const WithCache<const Value *> &V,
939 bool ForSigned, const SimplifyQuery &SQ);
940
941/// Return true if this function can prove that the instruction I will
942/// always transfer execution to one of its successors (including the next
943/// instruction that follows within a basic block). E.g. this is not
944/// guaranteed for function calls that could loop infinitely.
945///
946/// In other words, this function returns false for instructions that may
947/// transfer execution or fail to transfer execution in a way that is not
948/// captured in the CFG nor in the sequence of instructions within a basic
949/// block.
950///
951/// Undefined behavior is assumed not to happen, so e.g. division is
952/// guaranteed to transfer execution to the following instruction even
953/// though division by zero might cause undefined behavior.
954bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I);
955
956/// Returns true if this block does not contain a potential implicit exit.
957/// This is equivelent to saying that all instructions within the basic block
958/// are guaranteed to transfer execution to their successor within the basic
959/// block. This has the same assumptions w.r.t. undefined behavior as the
960/// instruction variant of this function.
961bool isGuaranteedToTransferExecutionToSuccessor(const BasicBlock *BB);
962
963/// Return true if every instruction in the range (Begin, End) is
964/// guaranteed to transfer execution to its static successor. \p ScanLimit
965/// bounds the search to avoid scanning huge blocks.
968 unsigned ScanLimit = 32);
969
970/// Same as previous, but with range expressed via iterator_range.
972 iterator_range<BasicBlock::const_iterator> Range, unsigned ScanLimit = 32);
973
974/// Return true if this function can prove that the instruction I
975/// is executed for every iteration of the loop L.
976///
977/// Note that this currently only considers the loop header.
978bool isGuaranteedToExecuteForEveryIteration(const Instruction *I,
979 const Loop *L);
980
981/// Return true if \p PoisonOp's user yields poison or raises UB if its
982/// operand \p PoisonOp is poison.
983///
984/// If \p PoisonOp is a vector or an aggregate and the operation's result is a
985/// single value, any poison element in /p PoisonOp should make the result
986/// poison or raise UB.
987///
988/// To filter out operands that raise UB on poison, you can use
989/// getGuaranteedNonPoisonOp.
990bool propagatesPoison(const Use &PoisonOp);
991
992/// Insert operands of I into Ops such that I will trigger undefined behavior
993/// if I is executed and that operand has a poison value.
994void getGuaranteedNonPoisonOps(const Instruction *I,
995 SmallVectorImpl<const Value *> &Ops);
996
997/// Insert operands of I into Ops such that I will trigger undefined behavior
998/// if I is executed and that operand is not a well-defined value
999/// (i.e. has undef bits or poison).
1000void getGuaranteedWellDefinedOps(const Instruction *I,
1001 SmallVectorImpl<const Value *> &Ops);
1002
1003/// Return true if the given instruction must trigger undefined behavior
1004/// when I is executed with any operands which appear in KnownPoison holding
1005/// a poison value at the point of execution.
1006bool mustTriggerUB(const Instruction *I,
1007 const SmallPtrSetImpl<const Value *> &KnownPoison);
1008
1009/// Return true if this function can prove that if Inst is executed
1010/// and yields a poison value or undef bits, then that will trigger
1011/// undefined behavior.
1012///
1013/// Note that this currently only considers the basic block that is
1014/// the parent of Inst.
1015bool programUndefinedIfUndefOrPoison(const Instruction *Inst);
1016bool programUndefinedIfPoison(const Instruction *Inst);
1017
1018/// canCreateUndefOrPoison returns true if Op can create undef or poison from
1019/// non-undef & non-poison operands.
1020/// For vectors, canCreateUndefOrPoison returns true if there is potential
1021/// poison or undef in any element of the result when vectors without
1022/// undef/poison poison are given as operands.
1023/// For example, given `Op = shl <2 x i32> %x, <0, 32>`, this function returns
1024/// true. If Op raises immediate UB but never creates poison or undef
1025/// (e.g. sdiv I, 0), canCreatePoison returns false.
1026///
1027/// \p ConsiderFlagsAndMetadata controls whether poison producing flags and
1028/// metadata on the instruction are considered. This can be used to see if the
1029/// instruction could still introduce undef or poison even without poison
1030/// generating flags and metadata which might be on the instruction.
1031/// (i.e. could the result of Op->dropPoisonGeneratingFlags() still create
1032/// poison or undef)
1033///
1034/// canCreatePoison returns true if Op can create poison from non-poison
1035/// operands.
1036bool canCreateUndefOrPoison(const Operator *Op,
1037 bool ConsiderFlagsAndMetadata = true);
1038bool canCreatePoison(const Operator *Op, bool ConsiderFlagsAndMetadata = true);
1039
1040/// Return true if V is poison given that ValAssumedPoison is already poison.
1041/// For example, if ValAssumedPoison is `icmp X, 10` and V is `icmp X, 5`,
1042/// impliesPoison returns true.
1043bool impliesPoison(const Value *ValAssumedPoison, const Value *V);
1044
1045/// Return true if this function can prove that V does not have undef bits
1046/// and is never poison. If V is an aggregate value or vector, check whether
1047/// all elements (except padding) are not undef or poison.
1048/// Note that this is different from canCreateUndefOrPoison because the
1049/// function assumes Op's operands are not poison/undef.
1050///
1051/// If CtxI and DT are specified this method performs flow-sensitive analysis
1052/// and returns true if it is guaranteed to be never undef or poison
1053/// immediately before the CtxI.
1054bool isGuaranteedNotToBeUndefOrPoison(const Value *V,
1055 AssumptionCache *AC = nullptr,
1056 const Instruction *CtxI = nullptr,
1057 const DominatorTree *DT = nullptr,
1058 unsigned Depth = 0);
1059
1060/// Returns true if V cannot be poison, but may be undef.
1061bool isGuaranteedNotToBePoison(const Value *V, AssumptionCache *AC = nullptr,
1062 const Instruction *CtxI = nullptr,
1063 const DominatorTree *DT = nullptr,
1064 unsigned Depth = 0);
1065
1068 const DominatorTree *DT = nullptr,
1069 unsigned Depth = 0) {
1070 // Takes an iterator as a position, passes down to Instruction *
1071 // implementation.
1072 return isGuaranteedNotToBePoison(V, AC, &*CtxI, DT, Depth);
1073}
1074
1075/// Returns true if V cannot be undef, but may be poison.
1076bool isGuaranteedNotToBeUndef(const Value *V, AssumptionCache *AC = nullptr,
1077 const Instruction *CtxI = nullptr,
1078 const DominatorTree *DT = nullptr,
1079 unsigned Depth = 0);
1080
1081/// Return true if undefined behavior would provable be executed on the path to
1082/// OnPathTo if Root produced a posion result. Note that this doesn't say
1083/// anything about whether OnPathTo is actually executed or whether Root is
1084/// actually poison. This can be used to assess whether a new use of Root can
1085/// be added at a location which is control equivalent with OnPathTo (such as
1086/// immediately before it) without introducing UB which didn't previously
1087/// exist. Note that a false result conveys no information.
1088bool mustExecuteUBIfPoisonOnPathTo(Instruction *Root,
1089 Instruction *OnPathTo,
1090 DominatorTree *DT);
1091
1092/// Specific patterns of select instructions we can match.
1095 SPF_SMIN, /// Signed minimum
1096 SPF_UMIN, /// Unsigned minimum
1097 SPF_SMAX, /// Signed maximum
1098 SPF_UMAX, /// Unsigned maximum
1099 SPF_FMINNUM, /// Floating point minnum
1100 SPF_FMAXNUM, /// Floating point maxnum
1101 SPF_ABS, /// Absolute value
1102 SPF_NABS /// Negated absolute value
1104
1105/// Behavior when a floating point min/max is given one NaN and one
1106/// non-NaN as input.
1108 SPNB_NA = 0, /// NaN behavior not applicable.
1109 SPNB_RETURNS_NAN, /// Given one NaN input, returns the NaN.
1110 SPNB_RETURNS_OTHER, /// Given one NaN input, returns the non-NaN.
1111 SPNB_RETURNS_ANY /// Given one NaN input, can return either (or
1112 /// it has been determined that no operands can
1113 /// be NaN).
1115
1118 SelectPatternNaNBehavior NaNBehavior; /// Only applicable if Flavor is
1119 /// SPF_FMINNUM or SPF_FMAXNUM.
1120 bool Ordered; /// When implementing this min/max pattern as
1121 /// fcmp; select, does the fcmp have to be
1122 /// ordered?
1123
1124 /// Return true if \p SPF is a min or a max pattern.
1126 return SPF != SPF_UNKNOWN && SPF != SPF_ABS && SPF != SPF_NABS;
1127 }
1128};
1129
1130/// Pattern match integer [SU]MIN, [SU]MAX and ABS idioms, returning the kind
1131/// and providing the out parameter results if we successfully match.
1132///
1133/// For ABS/NABS, LHS will be set to the input to the abs idiom. RHS will be
1134/// the negation instruction from the idiom.
1135///
1136/// If CastOp is not nullptr, also match MIN/MAX idioms where the type does
1137/// not match that of the original select. If this is the case, the cast
1138/// operation (one of Trunc,SExt,Zext) that must be done to transform the
1139/// type of LHS and RHS into the type of V is returned in CastOp.
1140///
1141/// For example:
1142/// %1 = icmp slt i32 %a, i32 4
1143/// %2 = sext i32 %a to i64
1144/// %3 = select i1 %1, i64 %2, i64 4
1145///
1146/// -> LHS = %a, RHS = i32 4, *CastOp = Instruction::SExt
1147///
1148SelectPatternResult matchSelectPattern(Value *V, Value *&LHS, Value *&RHS,
1149 Instruction::CastOps *CastOp = nullptr,
1150 unsigned Depth = 0);
1151
1153 const Value *&RHS) {
1154 Value *L = const_cast<Value *>(LHS);
1155 Value *R = const_cast<Value *>(RHS);
1156 auto Result = matchSelectPattern(const_cast<Value *>(V), L, R);
1157 LHS = L;
1158 RHS = R;
1159 return Result;
1160}
1161
1162/// Determine the pattern that a select with the given compare as its
1163/// predicate and given values as its true/false operands would match.
1164SelectPatternResult matchDecomposedSelectPattern(
1165 CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS,
1166 Instruction::CastOps *CastOp = nullptr, unsigned Depth = 0);
1167
1168/// Return the canonical comparison predicate for the specified
1169/// minimum/maximum flavor.
1170CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered = false);
1171
1172/// Return the inverse minimum/maximum flavor of the specified flavor.
1173/// For example, signed minimum is the inverse of signed maximum.
1175
1177
1178/// Return the minimum or maximum constant value for the specified integer
1179/// min/max flavor and type.
1180APInt getMinMaxLimit(SelectPatternFlavor SPF, unsigned BitWidth);
1181
1182/// Check if the values in \p VL are select instructions that can be converted
1183/// to a min or max (vector) intrinsic. Returns the intrinsic ID, if such a
1184/// conversion is possible, together with a bool indicating whether all select
1185/// conditions are only used by the selects. Otherwise return
1186/// Intrinsic::not_intrinsic.
1187std::pair<Intrinsic::ID, bool>
1188canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL);
1189
1190/// Attempt to match a simple first order recurrence cycle of the form:
1191/// %iv = phi Ty [%Start, %Entry], [%Inc, %backedge]
1192/// %inc = binop %iv, %step
1193/// OR
1194/// %iv = phi Ty [%Start, %Entry], [%Inc, %backedge]
1195/// %inc = binop %step, %iv
1196///
1197/// A first order recurrence is a formula with the form: X_n = f(X_(n-1))
1198///
1199/// A couple of notes on subtleties in that definition:
1200/// * The Step does not have to be loop invariant. In math terms, it can
1201/// be a free variable. We allow recurrences with both constant and
1202/// variable coefficients. Callers may wish to filter cases where Step
1203/// does not dominate P.
1204/// * For non-commutative operators, we will match both forms. This
1205/// results in some odd recurrence structures. Callers may wish to filter
1206/// out recurrences where the phi is not the LHS of the returned operator.
1207/// * Because of the structure matched, the caller can assume as a post
1208/// condition of the match the presence of a Loop with P's parent as it's
1209/// header *except* in unreachable code. (Dominance decays in unreachable
1210/// code.)
1211///
1212/// NOTE: This is intentional simple. If you want the ability to analyze
1213/// non-trivial loop conditons, see ScalarEvolution instead.
1214bool matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO, Value *&Start,
1215 Value *&Step);
1216
1217/// Analogous to the above, but starting from the binary operator
1218bool matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P, Value *&Start,
1219 Value *&Step);
1220
1221/// Return true if RHS is known to be implied true by LHS. Return false if
1222/// RHS is known to be implied false by LHS. Otherwise, return std::nullopt if
1223/// no implication can be made. A & B must be i1 (boolean) values or a vector of
1224/// such values. Note that the truth table for implication is the same as <=u on
1225/// i1 values (but not
1226/// <=s!). The truth table for both is:
1227/// | T | F (B)
1228/// T | T | F
1229/// F | T | T
1230/// (A)
1231std::optional<bool> isImpliedCondition(const Value *LHS, const Value *RHS,
1232 const DataLayout &DL,
1233 bool LHSIsTrue = true,
1234 unsigned Depth = 0);
1235std::optional<bool> isImpliedCondition(const Value *LHS,
1236 CmpInst::Predicate RHSPred,
1237 const Value *RHSOp0, const Value *RHSOp1,
1238 const DataLayout &DL,
1239 bool LHSIsTrue = true,
1240 unsigned Depth = 0);
1241
1242/// Return the boolean condition value in the context of the given instruction
1243/// if it is known based on dominating conditions.
1244std::optional<bool> isImpliedByDomCondition(const Value *Cond,
1245 const Instruction *ContextI,
1246 const DataLayout &DL);
1247std::optional<bool> isImpliedByDomCondition(CmpInst::Predicate Pred,
1248 const Value *LHS, const Value *RHS,
1249 const Instruction *ContextI,
1250 const DataLayout &DL);
1251
1252/// Call \p InsertAffected on all Values whose known bits / value may be
1253/// affected by the condition \p Cond. Used by AssumptionCache and
1254/// DomConditionCache.
1255void findValuesAffectedByCondition(Value *Cond, bool IsAssume,
1256 function_ref<void(Value *)> InsertAffected);
1257
1258} // end namespace llvm
1259
1260#endif // LLVM_ANALYSIS_VALUETRACKING_H
MachineBasicBlock MachineBasicBlock::iterator DebugLoc DL
This file contains the declarations for the subclasses of Constant, which represent the different fla...
bool End
Definition: ELF_riscv.cpp:480
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
Hexagon Common GEP
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
ConstantRange Range(APInt(BitWidth, Low), APInt(BitWidth, High))
static GCMetadataPrinterRegistry::Add< OcamlGCMetadataPrinter > Y("ocaml", "ocaml 3.10-compatible collector")
#define P(N)
const SmallVectorImpl< MachineOperand > & Cond
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Value * RHS
Value * LHS
Class for arbitrary precision integers.
Definition: APInt.h:78
static APInt getAllOnes(unsigned numBits)
Return an APInt of a specified width with all bits set.
Definition: APInt.h:212
int64_t getSExtValue() const
Get sign extended value.
Definition: APInt.h:1520
an instruction to allocate memory on the stack
Definition: Instructions.h:61
A cache of @llvm.assume calls within a function.
InstListType::const_iterator const_iterator
Definition: BasicBlock.h:178
InstListType::iterator iterator
Instruction iterators...
Definition: BasicBlock.h:177
Base class for all callable instructions (InvokeInst and CallInst) Holds everything related to callin...
Definition: InstrTypes.h:1236
Predicate
This enumeration lists the possible predicates for CmpInst subclasses.
Definition: InstrTypes.h:757
An array constant whose element type is a simple 1/2/4/8-byte integer or float/double,...
Definition: Constants.h:693
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:3074
This class represents an Operation in the Expression.
A parsed version of the target data layout string in and methods for querying it.
Definition: DataLayout.h:63
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree.
Definition: Dominators.h:162
Convenience struct for specifying and reasoning about fast-math flags.
Definition: FMF.h:20
bool noInfs() const
Definition: FMF.h:67
bool noNaNs() const
Definition: FMF.h:66
Metadata node.
Definition: Metadata.h:1069
This is a utility class that provides an abstraction for the common functionality between Instruction...
Definition: Operator.h:32
Provides information about what library functions are available for the current target.
The instances of the Type class are immutable: once they are created, they are never changed.
Definition: Type.h:45
LLVM Value Representation.
Definition: Value.h:74
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
bool haveNoCommonBitsSet(const WithCache< const Value * > &LHSCache, const WithCache< const Value * > &RHSCache, const SimplifyQuery &SQ)
Return true if LHS and RHS have no common bits set.
bool mustExecuteUBIfPoisonOnPathTo(Instruction *Root, Instruction *OnPathTo, DominatorTree *DT)
Return true if undefined behavior would provable be executed on the path to OnPathTo if Root produced...
Intrinsic::ID getInverseMinMaxIntrinsic(Intrinsic::ID MinMaxID)
@ Offset
Definition: DWP.cpp:480
OverflowResult
@ NeverOverflows
Never overflows.
@ AlwaysOverflowsHigh
Always overflows in the direction of signed/unsigned max value.
@ AlwaysOverflowsLow
Always overflows in the direction of signed/unsigned min value.
@ MayOverflow
May or may not overflow.
bool isValidAssumeForContext(const Instruction *I, const Instruction *CxtI, const DominatorTree *DT=nullptr, bool AllowEphemerals=false)
Return true if it is valid to use the assumptions provided by an assume intrinsic,...
bool canCreatePoison(const Operator *Op, bool ConsiderFlagsAndMetadata=true)
bool MaskedValueIsZero(const Value *V, const APInt &Mask, const SimplifyQuery &DL, unsigned Depth=0)
Return true if 'V & Mask' is known to be zero.
bool mustTriggerUB(const Instruction *I, const SmallPtrSetImpl< const Value * > &KnownPoison)
Return true if the given instruction must trigger undefined behavior when I is executed with any oper...
bool isSafeToSpeculativelyExecuteWithVariableReplaced(const Instruction *I)
Don't use information from its non-constant operands.
bool isOnlyUsedInZeroEqualityComparison(const Instruction *CxtI)
bool isSignBitCheck(ICmpInst::Predicate Pred, const APInt &RHS, bool &TrueIfSigned)
Given an exploded icmp instruction, return true if the comparison only checks the sign bit.
const Value * getArgumentAliasingToReturnedPointer(const CallBase *Call, bool MustPreserveNullness)
This function returns call pointer argument that is considered the same by aliasing rules.
bool isAssumeLikeIntrinsic(const Instruction *I)
Return true if it is an intrinsic that cannot be speculated but also cannot trap.
AllocaInst * findAllocaForValue(Value *V, bool OffsetZero=false)
Returns unique alloca where the value comes from, or nullptr.
APInt getMinMaxLimit(SelectPatternFlavor SPF, unsigned BitWidth)
Return the minimum or maximum constant value for the specified integer min/max flavor and type.
bool isKnownNeverInfinity(const Value *V, unsigned Depth, const SimplifyQuery &SQ)
Return true if the floating-point scalar value is not an infinity or if the floating-point vector val...
void getGuaranteedNonPoisonOps(const Instruction *I, SmallVectorImpl< const Value * > &Ops)
Insert operands of I into Ops such that I will trigger undefined behavior if I is executed and that o...
bool isOnlyUsedInZeroComparison(const Instruction *CxtI)
bool getConstantStringInfo(const Value *V, StringRef &Str, bool TrimAtNul=true)
This function computes the length of a null-terminated C string pointed to by V.
bool onlyUsedByLifetimeMarkersOrDroppableInsts(const Value *V)
Return true if the only users of this pointer are lifetime markers or droppable instructions.
bool getUnderlyingObjectsForCodeGen(const Value *V, SmallVectorImpl< Value * > &Objects)
This is a wrapper around getUnderlyingObjects and adds support for basic ptrtoint+arithmetic+inttoptr...
std::pair< Intrinsic::ID, bool > canConvertToMinOrMaxIntrinsic(ArrayRef< Value * > VL)
Check if the values in VL are select instructions that can be converted to a min or max (vector) intr...
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.
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 ...
Value * GetPointerBaseWithConstantOffset(Value *Ptr, int64_t &Offset, const DataLayout &DL, bool AllowNonInbounds=true)
Analyze the specified pointer to see if it can be expressed as a base pointer plus a constant offset.
const Value * getUnderlyingObject(const Value *V, unsigned MaxLookup=6)
This method strips off any GEP address adjustments, pointer casts or llvm.threadlocal....
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.
bool isKnownNeverInfOrNaN(const Value *V, unsigned Depth, const SimplifyQuery &SQ)
Return true if the floating-point value can never contain a NaN or infinity.
CmpInst::Predicate getMinMaxPred(SelectPatternFlavor SPF, bool Ordered=false)
Return the canonical comparison predicate for the specified minimum/maximum flavor.
void computeKnownBitsFromContext(const Value *V, KnownBits &Known, unsigned Depth, const SimplifyQuery &Q)
Merge bits known from context-dependent facts into Known.
bool isGuaranteedNotToBeUndef(const Value *V, AssumptionCache *AC=nullptr, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr, unsigned Depth=0)
Returns true if V cannot be undef, but may be poison.
ConstantRange computeConstantRange(const Value *V, bool ForSigned, bool UseInstrInfo=true, AssumptionCache *AC=nullptr, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr, unsigned Depth=0)
Determine the possible constant range of an integer or vector of integer value.
bool isOverflowIntrinsicNoWrap(const WithOverflowInst *WO, const DominatorTree &DT)
Returns true if the arithmetic part of the WO 's result is used only along the paths control dependen...
bool matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO, Value *&Start, Value *&Step)
Attempt to match a simple first order recurrence cycle of the form: iv = phi Ty [Start,...
bool isSafeToSpeculativelyExecuteWithOpcode(unsigned Opcode, const Instruction *Inst, const Instruction *CtxI=nullptr, AssumptionCache *AC=nullptr, const DominatorTree *DT=nullptr, const TargetLibraryInfo *TLI=nullptr, bool UseVariableInfo=true)
This returns the same result as isSafeToSpeculativelyExecute if Opcode is the actual opcode of Inst.
KnownBits analyzeKnownBitsFromAndXorOr(const Operator *I, const KnownBits &KnownLHS, const KnownBits &KnownRHS, unsigned Depth, const SimplifyQuery &SQ)
Using KnownBits LHS/RHS produce the known bits for logic op (and/xor/or).
OverflowResult computeOverflowForUnsignedMul(const Value *LHS, const Value *RHS, const SimplifyQuery &SQ, bool IsNSW=false)
SelectPatternFlavor getInverseMinMaxFlavor(SelectPatternFlavor SPF)
Return the inverse minimum/maximum flavor of the specified flavor.
constexpr unsigned MaxAnalysisRecursionDepth
Definition: ValueTracking.h:44
void getGuaranteedWellDefinedOps(const Instruction *I, SmallVectorImpl< const Value * > &Ops)
Insert operands of I into Ops such that I will trigger undefined behavior if I is executed and that o...
FPClassTest fneg(FPClassTest Mask)
Return the test mask which returns true if the value's sign bit is flipped.
OverflowResult computeOverflowForSignedSub(const Value *LHS, const Value *RHS, const SimplifyQuery &SQ)
std::tuple< Value *, FPClassTest, FPClassTest > fcmpImpliesClass(CmpInst::Predicate Pred, const Function &F, Value *LHS, Value *RHS, bool LookThroughSrc=true)
Compute the possible floating-point classes that LHS could be based on fcmp \Pred LHS,...
SelectPatternFlavor
Specific patterns of select instructions we can match.
@ SPF_ABS
Floating point maxnum.
@ SPF_NABS
Absolute value.
@ SPF_FMAXNUM
Floating point minnum.
@ SPF_UMIN
Signed minimum.
@ SPF_UMAX
Signed maximum.
@ SPF_SMAX
Unsigned minimum.
@ SPF_UNKNOWN
@ SPF_FMINNUM
Unsigned maximum.
bool isIntrinsicReturningPointerAliasingArgumentWithoutCapturing(const CallBase *Call, bool MustPreserveNullness)
{launder,strip}.invariant.group returns pointer that aliases its argument, and it only captures point...
void adjustKnownBitsForSelectArm(KnownBits &Known, Value *Cond, Value *Arm, bool Invert, unsigned Depth, const SimplifyQuery &Q)
Adjust Known for the given select Arm to include information from the select Cond.
bool impliesPoison(const Value *ValAssumedPoison, const Value *V)
Return true if V is poison given that ValAssumedPoison is already poison.
FPClassTest
Floating-point class tests, supported by 'is_fpclass' intrinsic.
bool programUndefinedIfPoison(const Instruction *Inst)
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...
bool programUndefinedIfUndefOrPoison(const Instruction *Inst)
Return true if this function can prove that if Inst is executed and yields a poison value or undef bi...
bool isSafeToSpeculativelyExecute(const Instruction *I, const Instruction *CtxI=nullptr, AssumptionCache *AC=nullptr, const DominatorTree *DT=nullptr, const TargetLibraryInfo *TLI=nullptr, bool UseVariableInfo=true)
Return true if the instruction does not have any effects besides calculating the result and does not ...
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 'len+1'.
OverflowResult computeOverflowForSignedMul(const Value *LHS, const Value *RHS, const SimplifyQuery &SQ)
ConstantRange getVScaleRange(const Function *F, unsigned BitWidth)
Determine the possible constant range of vscale with the given bit width, based on the vscale_range f...
bool canCreateUndefOrPoison(const Operator *Op, bool ConsiderFlagsAndMetadata=true)
canCreateUndefOrPoison returns true if Op can create undef or poison from non-undef & non-poison oper...
bool isKnownInversion(const Value *X, const Value *Y)
Return true iff:
bool isKnownNonZero(const Value *V, const SimplifyQuery &Q, unsigned Depth=0)
Return true if the given value is known to be non-zero when defined.
bool onlyUsedByLifetimeMarkers(const Value *V)
Return true if the only users of this pointer are lifetime markers.
Intrinsic::ID getIntrinsicForCallSite(const CallBase &CB, const TargetLibraryInfo *TLI)
Map a call instruction to an intrinsic ID.
@ Other
Any other memory.
const Value * getUnderlyingObjectAggressive(const Value *V)
Like getUnderlyingObject(), but will try harder to find a single underlying object.
OverflowResult computeOverflowForSignedAdd(const WithCache< const Value * > &LHS, const WithCache< const Value * > &RHS, const SimplifyQuery &SQ)
bool propagatesPoison(const Use &PoisonOp)
Return true if PoisonOp's user yields poison or raises UB if its operand PoisonOp is poison.
bool isKnownNegative(const Value *V, const SimplifyQuery &DL, unsigned Depth=0)
Returns true if the given value is known be negative (i.e.
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.
@ Add
Sum of integers.
ConstantRange computeConstantRangeIncludingKnownBits(const WithCache< const Value * > &V, bool ForSigned, const SimplifyQuery &SQ)
Combine constant ranges from computeConstantRange() and computeKnownBits().
SelectPatternNaNBehavior
Behavior when a floating point min/max is given one NaN and one non-NaN as input.
@ SPNB_RETURNS_NAN
NaN behavior not applicable.
@ SPNB_RETURNS_OTHER
Given one NaN input, returns the NaN.
@ SPNB_RETURNS_ANY
Given one NaN input, returns the non-NaN.
void computeKnownBits(const Value *V, KnownBits &Known, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr, bool UseInstrInfo=true)
Determine which bits of V are known to be either zero or one and return them in the KnownZero/KnownOn...
DWARFExpression::Operation Op
bool isGuaranteedNotToBeUndefOrPoison(const Value *V, AssumptionCache *AC=nullptr, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr, unsigned Depth=0)
Return true if this function can prove that V does not have undef bits and is never poison.
ArrayRef(const T &OneElt) -> ArrayRef< T >
constexpr unsigned BitWidth
Definition: BitmaskEnum.h:191
SelectPatternResult matchDecomposedSelectPattern(CmpInst *CmpI, Value *TrueVal, Value *FalseVal, Value *&LHS, Value *&RHS, Instruction::CastOps *CastOp=nullptr, unsigned Depth=0)
Determine the pattern that a select with the given compare as its predicate and given values as its t...
OverflowResult computeOverflowForUnsignedSub(const Value *LHS, const Value *RHS, const SimplifyQuery &SQ)
bool isGuaranteedToTransferExecutionToSuccessor(const Instruction *I)
Return true if this function can prove that the instruction I will always transfer execution to one o...
std::pair< Value *, FPClassTest > fcmpToClassTest(CmpInst::Predicate Pred, const Function &F, Value *LHS, Value *RHS, bool LookThroughSrc=true)
Returns a pair of values, which if passed to llvm.is.fpclass, returns the same result as an fcmp with...
Value * isBytewiseValue(Value *V, const DataLayout &DL)
If the specified value can be set by repeating the same byte in memory, return the i8 value that it i...
void getUnderlyingObjects(const Value *V, SmallVectorImpl< const Value * > &Objects, const LoopInfo *LI=nullptr, unsigned MaxLookup=6)
This method is similar to getUnderlyingObject except that it can look through phi and select instruct...
std::optional< bool > computeKnownFPSignBit(const Value *V, unsigned Depth, const SimplifyQuery &SQ)
Return false if we can prove that the specified FP value's sign bit is 0.
bool cannotBeOrderedLessThanZero(const Value *V, unsigned Depth, const SimplifyQuery &SQ)
Return true if we can prove that the specified FP value is either NaN or never less than -0....
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 cannotBeNegativeZero(const Value *V, unsigned Depth, const SimplifyQuery &SQ)
Return true if we can prove that the specified FP value is never equal to -0.0.
OverflowResult computeOverflowForUnsignedAdd(const WithCache< const Value * > &LHS, const WithCache< const Value * > &RHS, const SimplifyQuery &SQ)
bool isKnownNeverNaN(const Value *V, unsigned Depth, const SimplifyQuery &SQ)
Return true if the floating-point scalar value is not a NaN or if the floating-point vector value has...
std::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 isGEPBasedOnPointerToString(const GEPOperator *GEP, unsigned CharSize=8)
Returns true if the GEP is based on a pointer to a string (array of.
APInt operator|(APInt a, const APInt &b)
Definition: APInt.h:2090
bool isGuaranteedNotToBePoison(const Value *V, AssumptionCache *AC=nullptr, const Instruction *CtxI=nullptr, const DominatorTree *DT=nullptr, unsigned Depth=0)
Returns true if V cannot be poison, but may be undef.
KnownFPClass computeKnownFPClass(const Value *V, const APInt &DemandedElts, FPClassTest InterestedClasses, unsigned Depth, const SimplifyQuery &SQ)
Determine which floating-point classes are valid for V, and return them in KnownFPClass bit sets.
void computeKnownBitsFromRangeMetadata(const MDNode &Ranges, KnownBits &Known)
Compute known bits from the range metadata.
Value * FindInsertedValue(Value *V, ArrayRef< unsigned > idx_range, std::optional< BasicBlock::iterator > InsertBefore=std::nullopt)
Given an aggregate and an sequence of indices, see if the scalar value indexed is already around as a...
bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW=false, bool AllowPoison=true)
Return true if the two given values are negation.
bool isKnownPositive(const Value *V, const SimplifyQuery &SQ, unsigned Depth=0)
Returns true if the given value is known be positive (i.e.
bool isKnownNonNegative(const Value *V, const SimplifyQuery &SQ, unsigned Depth=0)
Returns true if the give value is known to be non-negative.
unsigned ComputeMaxSignificantBits(const Value *Op, const DataLayout &DL, unsigned Depth=0, AssumptionCache *AC=nullptr, const Instruction *CxtI=nullptr, const DominatorTree *DT=nullptr)
Get the upper bound on bit size for this Value Op as a signed integer.
bool mayHaveNonDefUseDependency(const Instruction &I)
Returns true if the result or effects of the given instructions I depend values not reachable through...
std::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.
void findValuesAffectedByCondition(Value *Cond, bool IsAssume, function_ref< void(Value *)> InsertAffected)
Call InsertAffected on all Values whose known bits / value may be affected by the condition Cond.
Represents offset+length into a ConstantDataArray.
uint64_t Length
Length of the slice.
uint64_t Offset
Slice starts at this Offset.
uint64_t operator[](unsigned I) const
Convenience accessor for elements in the slice.
void move(uint64_t Delta)
Moves the Offset and adjusts Length accordingly.
const ConstantDataArray * Array
ConstantDataArray pointer.
bool isKnownAlwaysNaN() const
Return true if it's known this must always be a nan.
FPClassTest KnownFPClasses
Floating-point classes the value could be one of.
bool isKnownNeverInfinity() const
Return true if it's known this can never be an infinity.
bool cannotBeOrderedGreaterThanZero() const
Return true if we can prove that the analyzed floating-point value is either NaN or never greater tha...
static constexpr FPClassTest OrderedGreaterThanZeroMask
static constexpr FPClassTest OrderedLessThanZeroMask
void knownNot(FPClassTest RuleOut)
bool isKnownNeverZero() const
Return true if it's known this can never be a zero.
void copysign(const KnownFPClass &Sign)
bool isKnownNeverSubnormal() const
Return true if it's known this can never be a subnormal.
bool isKnownAlways(FPClassTest Mask) const
bool isKnownNeverLogicalNegZero(const Function &F, Type *Ty) const
Return true if it's know this can never be interpreted as a negative zero.
bool isKnownNeverLogicalPosZero(const Function &F, Type *Ty) const
Return true if it's know this can never be interpreted as a positive zero.
KnownFPClass & operator|=(const KnownFPClass &RHS)
void propagateCanonicalizingSrc(const KnownFPClass &Src, const Function &F, Type *Ty)
Report known classes if Src is evaluated through a potentially canonicalizing operation.
void propagateDenormal(const KnownFPClass &Src, const Function &F, Type *Ty)
Propagate knowledge from a source value that could be a denormal or zero.
bool isUnknown() const
bool isKnownNeverNegInfinity() const
Return true if it's known this can never be -infinity.
bool isKnownNeverNegSubnormal() const
Return true if it's known this can never be a negative subnormal.
bool isKnownNeverPosZero() const
Return true if it's known this can never be a literal positive zero.
std::optional< bool > SignBit
std::nullopt if the sign bit is unknown, true if the sign bit is definitely set or false if the sign ...
bool isKnownNeverNaN() const
Return true if it's known this can never be a nan.
bool isKnownNever(FPClassTest Mask) const
Return true if it's known this can never be one of the mask entries.
bool isKnownNeverNegZero() const
Return true if it's known this can never be a negative zero.
bool isKnownNeverLogicalZero(const Function &F, Type *Ty) const
Return true if it's know this can never be interpreted as a zero.
void propagateNaN(const KnownFPClass &Src, bool PreserveSign=false)
bool cannotBeOrderedLessThanZero() const
Return true if we can prove that the analyzed floating-point value is either NaN or never less than -...
void signBitMustBeOne()
Assume the sign bit is one.
void signBitMustBeZero()
Assume the sign bit is zero.
bool isKnownNeverPosInfinity() const
Return true if it's known this can never be +infinity.
bool operator==(KnownFPClass Other) const
bool signBitIsZeroOrNaN() const
Return true if the sign bit must be 0, ignoring the sign of nans.
bool isKnownNeverPosSubnormal() const
Return true if it's known this can never be a positive subnormal.
SelectPatternFlavor Flavor
bool Ordered
Only applicable if Flavor is SPF_FMINNUM or SPF_FMAXNUM.
static bool isMinOrMax(SelectPatternFlavor SPF)
When implementing this min/max pattern as fcmp; select, does the fcmp have to be ordered?
SelectPatternNaNBehavior NaNBehavior