1//===-- llvm/Operator.h - Operator utility subclass -------------*- 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 defines various classes for working with Instructions and
10// ConstantExprs.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_IR_OPERATOR_H
15#define LLVM_IR_OPERATOR_H
16
17#include "llvm/ADT/None.h"
18#include "llvm/ADT/Optional.h"
19#include "llvm/IR/Constants.h"
20#include "llvm/IR/Instruction.h"
21#include "llvm/IR/Type.h"
22#include "llvm/IR/Value.h"
23#include "llvm/Support/Casting.h"
24#include <cstddef>
25
26namespace llvm {
27
28/// This is a utility class that provides an abstraction for the common
29/// functionality between Instructions and ConstantExprs.
30class Operator : public User {
31public:
32  // The Operator class is intended to be used as a utility, and is never itself
33  // instantiated.
34  Operator() = delete;
35  ~Operator() = delete;
36
37  void *operator new(size_t s) = delete;
38
39  /// Return the opcode for this Instruction or ConstantExpr.
40  unsigned getOpcode() const {
41    if (const Instruction *I = dyn_cast<Instruction>(this))
42      return I->getOpcode();
43    return cast<ConstantExpr>(this)->getOpcode();
44  }
45
46  /// If V is an Instruction or ConstantExpr, return its opcode.
47  /// Otherwise return UserOp1.
48  static unsigned getOpcode(const Value *V) {
49    if (const Instruction *I = dyn_cast<Instruction>(V))
50      return I->getOpcode();
51    if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
52      return CE->getOpcode();
53    return Instruction::UserOp1;
54  }
55
56  static bool classof(const Instruction *) { return true; }
57  static bool classof(const ConstantExpr *) { return true; }
58  static bool classof(const Value *V) {
59    return isa<Instruction>(V) || isa<ConstantExpr>(V);
60  }
61};
62
63/// Utility class for integer operators which may exhibit overflow - Add, Sub,
64/// Mul, and Shl. It does not include SDiv, despite that operator having the
65/// potential for overflow.
66class OverflowingBinaryOperator : public Operator {
67public:
68  enum {
69    AnyWrap        = 0,
70    NoUnsignedWrap = (1 << 0),
71    NoSignedWrap   = (1 << 1)
72  };
73
74private:
75  friend class Instruction;
76  friend class ConstantExpr;
77
78  void setHasNoUnsignedWrap(bool B) {
79    SubclassOptionalData =
80      (SubclassOptionalData & ~NoUnsignedWrap) | (B * NoUnsignedWrap);
81  }
82  void setHasNoSignedWrap(bool B) {
83    SubclassOptionalData =
84      (SubclassOptionalData & ~NoSignedWrap) | (B * NoSignedWrap);
85  }
86
87public:
88  /// Test whether this operation is known to never
89  /// undergo unsigned overflow, aka the nuw property.
90  bool hasNoUnsignedWrap() const {
91    return SubclassOptionalData & NoUnsignedWrap;
92  }
93
94  /// Test whether this operation is known to never
95  /// undergo signed overflow, aka the nsw property.
96  bool hasNoSignedWrap() const {
97    return (SubclassOptionalData & NoSignedWrap) != 0;
98  }
99
100  static bool classof(const Instruction *I) {
101    return I->getOpcode() == Instruction::Add ||
102           I->getOpcode() == Instruction::Sub ||
103           I->getOpcode() == Instruction::Mul ||
104           I->getOpcode() == Instruction::Shl;
105  }
106  static bool classof(const ConstantExpr *CE) {
107    return CE->getOpcode() == Instruction::Add ||
108           CE->getOpcode() == Instruction::Sub ||
109           CE->getOpcode() == Instruction::Mul ||
110           CE->getOpcode() == Instruction::Shl;
111  }
112  static bool classof(const Value *V) {
113    return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
114           (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
115  }
116};
117
118/// A udiv or sdiv instruction, which can be marked as "exact",
119/// indicating that no bits are destroyed.
120class PossiblyExactOperator : public Operator {
121public:
122  enum {
123    IsExact = (1 << 0)
124  };
125
126private:
127  friend class Instruction;
128  friend class ConstantExpr;
129
130  void setIsExact(bool B) {
131    SubclassOptionalData = (SubclassOptionalData & ~IsExact) | (B * IsExact);
132  }
133
134public:
135  /// Test whether this division is known to be exact, with zero remainder.
136  bool isExact() const {
137    return SubclassOptionalData & IsExact;
138  }
139
140  static bool isPossiblyExactOpcode(unsigned OpC) {
141    return OpC == Instruction::SDiv ||
142           OpC == Instruction::UDiv ||
143           OpC == Instruction::AShr ||
144           OpC == Instruction::LShr;
145  }
146
147  static bool classof(const ConstantExpr *CE) {
148    return isPossiblyExactOpcode(CE->getOpcode());
149  }
150  static bool classof(const Instruction *I) {
151    return isPossiblyExactOpcode(I->getOpcode());
152  }
153  static bool classof(const Value *V) {
154    return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
155           (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
156  }
157};
158
159/// Convenience struct for specifying and reasoning about fast-math flags.
160class FastMathFlags {
161private:
162  friend class FPMathOperator;
163
164  unsigned Flags = 0;
165
166  FastMathFlags(unsigned F) {
167    // If all 7 bits are set, turn this into -1. If the number of bits grows,
168    // this must be updated. This is intended to provide some forward binary
169    // compatibility insurance for the meaning of 'fast' in case bits are added.
170    if (F == 0x7F) Flags = ~0U;
171    else Flags = F;
172  }
173
174public:
175  // This is how the bits are used in Value::SubclassOptionalData so they
176  // should fit there too.
177  // WARNING: We're out of space. SubclassOptionalData only has 7 bits. New
178  // functionality will require a change in how this information is stored.
179  enum {
180    AllowReassoc    = (1 << 0),
181    NoNaNs          = (1 << 1),
182    NoInfs          = (1 << 2),
183    NoSignedZeros   = (1 << 3),
184    AllowReciprocal = (1 << 4),
185    AllowContract   = (1 << 5),
186    ApproxFunc      = (1 << 6)
187  };
188
189  FastMathFlags() = default;
190
191  static FastMathFlags getFast() {
192    FastMathFlags FMF;
193    FMF.setFast();
194    return FMF;
195  }
196
197  bool any() const { return Flags != 0; }
198  bool none() const { return Flags == 0; }
199  bool all() const { return Flags == ~0U; }
200
201  void clear() { Flags = 0; }
202  void set()   { Flags = ~0U; }
203
204  /// Flag queries
205  bool allowReassoc() const    { return 0 != (Flags & AllowReassoc); }
206  bool noNaNs() const          { return 0 != (Flags & NoNaNs); }
207  bool noInfs() const          { return 0 != (Flags & NoInfs); }
208  bool noSignedZeros() const   { return 0 != (Flags & NoSignedZeros); }
209  bool allowReciprocal() const { return 0 != (Flags & AllowReciprocal); }
210  bool allowContract() const   { return 0 != (Flags & AllowContract); }
211  bool approxFunc() const      { return 0 != (Flags & ApproxFunc); }
212  /// 'Fast' means all bits are set.
213  bool isFast() const          { return all(); }
214
215  /// Flag setters
216  void setAllowReassoc(bool B = true) {
217    Flags = (Flags & ~AllowReassoc) | B * AllowReassoc;
218  }
219  void setNoNaNs(bool B = true) {
220    Flags = (Flags & ~NoNaNs) | B * NoNaNs;
221  }
222  void setNoInfs(bool B = true) {
223    Flags = (Flags & ~NoInfs) | B * NoInfs;
224  }
225  void setNoSignedZeros(bool B = true) {
226    Flags = (Flags & ~NoSignedZeros) | B * NoSignedZeros;
227  }
228  void setAllowReciprocal(bool B = true) {
229    Flags = (Flags & ~AllowReciprocal) | B * AllowReciprocal;
230  }
231  void setAllowContract(bool B = true) {
232    Flags = (Flags & ~AllowContract) | B * AllowContract;
233  }
234  void setApproxFunc(bool B = true) {
235    Flags = (Flags & ~ApproxFunc) | B * ApproxFunc;
236  }
237  void setFast(bool B = true) { B ? set() : clear(); }
238
239  void operator&=(const FastMathFlags &OtherFlags) {
240    Flags &= OtherFlags.Flags;
241  }
242};
243
244/// Utility class for floating point operations which can have
245/// information about relaxed accuracy requirements attached to them.
246class FPMathOperator : public Operator {
247private:
248  friend class Instruction;
249
250  /// 'Fast' means all bits are set.
251  void setFast(bool B) {
252    setHasAllowReassoc(B);
253    setHasNoNaNs(B);
254    setHasNoInfs(B);
255    setHasNoSignedZeros(B);
256    setHasAllowReciprocal(B);
257    setHasAllowContract(B);
258    setHasApproxFunc(B);
259  }
260
261  void setHasAllowReassoc(bool B) {
262    SubclassOptionalData =
263    (SubclassOptionalData & ~FastMathFlags::AllowReassoc) |
264    (B * FastMathFlags::AllowReassoc);
265  }
266
267  void setHasNoNaNs(bool B) {
268    SubclassOptionalData =
269      (SubclassOptionalData & ~FastMathFlags::NoNaNs) |
270      (B * FastMathFlags::NoNaNs);
271  }
272
273  void setHasNoInfs(bool B) {
274    SubclassOptionalData =
275      (SubclassOptionalData & ~FastMathFlags::NoInfs) |
276      (B * FastMathFlags::NoInfs);
277  }
278
279  void setHasNoSignedZeros(bool B) {
280    SubclassOptionalData =
281      (SubclassOptionalData & ~FastMathFlags::NoSignedZeros) |
282      (B * FastMathFlags::NoSignedZeros);
283  }
284
285  void setHasAllowReciprocal(bool B) {
286    SubclassOptionalData =
287      (SubclassOptionalData & ~FastMathFlags::AllowReciprocal) |
288      (B * FastMathFlags::AllowReciprocal);
289  }
290
291  void setHasAllowContract(bool B) {
292    SubclassOptionalData =
293        (SubclassOptionalData & ~FastMathFlags::AllowContract) |
294        (B * FastMathFlags::AllowContract);
295  }
296
297  void setHasApproxFunc(bool B) {
298    SubclassOptionalData =
299        (SubclassOptionalData & ~FastMathFlags::ApproxFunc) |
300        (B * FastMathFlags::ApproxFunc);
301  }
302
303  /// Convenience function for setting multiple fast-math flags.
304  /// FMF is a mask of the bits to set.
305  void setFastMathFlags(FastMathFlags FMF) {
306    SubclassOptionalData |= FMF.Flags;
307  }
308
309  /// Convenience function for copying all fast-math flags.
310  /// All values in FMF are transferred to this operator.
311  void copyFastMathFlags(FastMathFlags FMF) {
312    SubclassOptionalData = FMF.Flags;
313  }
314
315public:
316  /// Test if this operation allows all non-strict floating-point transforms.
317  bool isFast() const {
318    return ((SubclassOptionalData & FastMathFlags::AllowReassoc) != 0 &&
319            (SubclassOptionalData & FastMathFlags::NoNaNs) != 0 &&
320            (SubclassOptionalData & FastMathFlags::NoInfs) != 0 &&
321            (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0 &&
322            (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0 &&
323            (SubclassOptionalData & FastMathFlags::AllowContract) != 0 &&
324            (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0);
325  }
326
327  /// Test if this operation may be simplified with reassociative transforms.
328  bool hasAllowReassoc() const {
329    return (SubclassOptionalData & FastMathFlags::AllowReassoc) != 0;
330  }
331
332  /// Test if this operation's arguments and results are assumed not-NaN.
333  bool hasNoNaNs() const {
334    return (SubclassOptionalData & FastMathFlags::NoNaNs) != 0;
335  }
336
337  /// Test if this operation's arguments and results are assumed not-infinite.
338  bool hasNoInfs() const {
339    return (SubclassOptionalData & FastMathFlags::NoInfs) != 0;
340  }
341
342  /// Test if this operation can ignore the sign of zero.
343  bool hasNoSignedZeros() const {
344    return (SubclassOptionalData & FastMathFlags::NoSignedZeros) != 0;
345  }
346
347  /// Test if this operation can use reciprocal multiply instead of division.
348  bool hasAllowReciprocal() const {
349    return (SubclassOptionalData & FastMathFlags::AllowReciprocal) != 0;
350  }
351
352  /// Test if this operation can be floating-point contracted (FMA).
353  bool hasAllowContract() const {
354    return (SubclassOptionalData & FastMathFlags::AllowContract) != 0;
355  }
356
357  /// Test if this operation allows approximations of math library functions or
358  /// intrinsics.
359  bool hasApproxFunc() const {
360    return (SubclassOptionalData & FastMathFlags::ApproxFunc) != 0;
361  }
362
363  /// Convenience function for getting all the fast-math flags
364  FastMathFlags getFastMathFlags() const {
365    return FastMathFlags(SubclassOptionalData);
366  }
367
368  /// Get the maximum error permitted by this operation in ULPs. An accuracy of
369  /// 0.0 means that the operation should be performed with the default
370  /// precision.
371  float getFPAccuracy() const;
372
373  static bool classof(const Value *V) {
374    unsigned Opcode;
375    if (auto *I = dyn_cast<Instruction>(V))
376      Opcode = I->getOpcode();
377    else if (auto *CE = dyn_cast<ConstantExpr>(V))
378      Opcode = CE->getOpcode();
379    else
380      return false;
381
382    switch (Opcode) {
383    case Instruction::FNeg:
384    case Instruction::FAdd:
385    case Instruction::FSub:
386    case Instruction::FMul:
387    case Instruction::FDiv:
388    case Instruction::FRem:
389    // FIXME: To clean up and correct the semantics of fast-math-flags, FCmp
390    //        should not be treated as a math op, but the other opcodes should.
391    //        This would make things consistent with Select/PHI (FP value type
392    //        determines whether they are math ops and, therefore, capable of
393    //        having fast-math-flags).
394    case Instruction::FCmp:
395      return true;
396    case Instruction::PHI:
397    case Instruction::Select:
398    case Instruction::Call: {
399      Type *Ty = V->getType();
400      while (ArrayType *ArrTy = dyn_cast<ArrayType>(Ty))
401        Ty = ArrTy->getElementType();
402      return Ty->isFPOrFPVectorTy();
403    }
404    default:
405      return false;
406    }
407  }
408};
409
410/// A helper template for defining operators for individual opcodes.
411template<typename SuperClass, unsigned Opc>
412class ConcreteOperator : public SuperClass {
413public:
414  static bool classof(const Instruction *I) {
415    return I->getOpcode() == Opc;
416  }
417  static bool classof(const ConstantExpr *CE) {
418    return CE->getOpcode() == Opc;
419  }
420  static bool classof(const Value *V) {
421    return (isa<Instruction>(V) && classof(cast<Instruction>(V))) ||
422           (isa<ConstantExpr>(V) && classof(cast<ConstantExpr>(V)));
423  }
424};
425
426class AddOperator
427  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Add> {
428};
429class SubOperator
430  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Sub> {
431};
432class MulOperator
433  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Mul> {
434};
435class ShlOperator
436  : public ConcreteOperator<OverflowingBinaryOperator, Instruction::Shl> {
437};
438
439class SDivOperator
440  : public ConcreteOperator<PossiblyExactOperator, Instruction::SDiv> {
441};
442class UDivOperator
443  : public ConcreteOperator<PossiblyExactOperator, Instruction::UDiv> {
444};
445class AShrOperator
446  : public ConcreteOperator<PossiblyExactOperator, Instruction::AShr> {
447};
448class LShrOperator
449  : public ConcreteOperator<PossiblyExactOperator, Instruction::LShr> {
450};
451
452class ZExtOperator : public ConcreteOperator<Operator, Instruction::ZExt> {};
453
454class GEPOperator
455  : public ConcreteOperator<Operator, Instruction::GetElementPtr> {
456  friend class GetElementPtrInst;
457  friend class ConstantExpr;
458
459  enum {
460    IsInBounds = (1 << 0),
461    // InRangeIndex: bits 1-6
462  };
463
464  void setIsInBounds(bool B) {
465    SubclassOptionalData =
466      (SubclassOptionalData & ~IsInBounds) | (B * IsInBounds);
467  }
468
469public:
470  /// Test whether this is an inbounds GEP, as defined by LangRef.html.
471  bool isInBounds() const {
472    return SubclassOptionalData & IsInBounds;
473  }
474
475  /// Returns the offset of the index with an inrange attachment, or None if
476  /// none.
477  Optional<unsigned> getInRangeIndex() const {
478    if (SubclassOptionalData >> 1 == 0) return None;
479    return (SubclassOptionalData >> 1) - 1;
480  }
481
482  inline op_iterator       idx_begin()       { return op_begin()+1; }
483  inline const_op_iterator idx_begin() const { return op_begin()+1; }
484  inline op_iterator       idx_end()         { return op_end(); }
485  inline const_op_iterator idx_end()   const { return op_end(); }
486
487  Value *getPointerOperand() {
488    return getOperand(0);
489  }
490  const Value *getPointerOperand() const {
491    return getOperand(0);
492  }
493  static unsigned getPointerOperandIndex() {
494    return 0U;                      // get index for modifying correct operand
495  }
496
497  /// Method to return the pointer operand as a PointerType.
498  Type *getPointerOperandType() const {
499    return getPointerOperand()->getType();
500  }
501
502  Type *getSourceElementType() const;
503  Type *getResultElementType() const;
504
505  /// Method to return the address space of the pointer operand.
506  unsigned getPointerAddressSpace() const {
507    return getPointerOperandType()->getPointerAddressSpace();
508  }
509
510  unsigned getNumIndices() const {  // Note: always non-negative
511    return getNumOperands() - 1;
512  }
513
514  bool hasIndices() const {
515    return getNumOperands() > 1;
516  }
517
518  /// Return true if all of the indices of this GEP are zeros.
519  /// If so, the result pointer and the first operand have the same
520  /// value, just potentially different types.
521  bool hasAllZeroIndices() const {
522    for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {
523      if (ConstantInt *C = dyn_cast<ConstantInt>(I))
524        if (C->isZero())
525          continue;
526      return false;
527    }
528    return true;
529  }
530
531  /// Return true if all of the indices of this GEP are constant integers.
532  /// If so, the result pointer and the first operand have
533  /// a constant offset between them.
534  bool hasAllConstantIndices() const {
535    for (const_op_iterator I = idx_begin(), E = idx_end(); I != E; ++I) {
536      if (!isa<ConstantInt>(I))
537        return false;
538    }
539    return true;
540  }
541
542  unsigned countNonConstantIndices() const {
543    return count_if(make_range(idx_begin(), idx_end()), [](const Use& use) {
544        return !isa<ConstantInt>(*use);
545      });
546  }
547
548  /// Compute the maximum alignment that this GEP is garranteed to preserve.
549  Align getMaxPreservedAlignment(const DataLayout &DL) const;
550
551  /// Accumulate the constant address offset of this GEP if possible.
552  ///
553  /// This routine accepts an APInt into which it will try to accumulate the
554  /// constant offset of this GEP.
555  ///
556  /// If \p ExternalAnalysis is provided it will be used to calculate a offset
557  /// when a operand of GEP is not constant.
558  /// For example, for a value \p ExternalAnalysis might try to calculate a
559  /// lower bound. If \p ExternalAnalysis is successful, it should return true.
560  ///
561  /// If the \p ExternalAnalysis returns false or the value returned by \p
562  /// ExternalAnalysis results in a overflow/underflow, this routine returns
563  /// false and the value of the offset APInt is undefined (it is *not*
564  /// preserved!).
565  ///
566  /// The APInt passed into this routine must be at exactly as wide as the
567  /// IntPtr type for the address space of the base GEP pointer.
568  bool accumulateConstantOffset(
569      const DataLayout &DL, APInt &Offset,
570      function_ref<bool(Value &, APInt &)> ExternalAnalysis = nullptr) const;
571};
572
573class PtrToIntOperator
574    : public ConcreteOperator<Operator, Instruction::PtrToInt> {
575  friend class PtrToInt;
576  friend class ConstantExpr;
577
578public:
579  Value *getPointerOperand() {
580    return getOperand(0);
581  }
582  const Value *getPointerOperand() const {
583    return getOperand(0);
584  }
585
586  static unsigned getPointerOperandIndex() {
587    return 0U;                      // get index for modifying correct operand
588  }
589
590  /// Method to return the pointer operand as a PointerType.
591  Type *getPointerOperandType() const {
592    return getPointerOperand()->getType();
593  }
594
595  /// Method to return the address space of the pointer operand.
596  unsigned getPointerAddressSpace() const {
597    return cast<PointerType>(getPointerOperandType())->getAddressSpace();
598  }
599};
600
601class BitCastOperator
602    : public ConcreteOperator<Operator, Instruction::BitCast> {
603  friend class BitCastInst;
604  friend class ConstantExpr;
605
606public:
607  Type *getSrcTy() const {
608    return getOperand(0)->getType();
609  }
610
611  Type *getDestTy() const {
612    return getType();
613  }
614};
615
616class AddrSpaceCastOperator
617    : public ConcreteOperator<Operator, Instruction::AddrSpaceCast> {
618  friend class AddrSpaceCastInst;
619  friend class ConstantExpr;
620
621public:
622  Value *getPointerOperand() { return getOperand(0); }
623
624  const Value *getPointerOperand() const { return getOperand(0); }
625
626  unsigned getSrcAddressSpace() const {
627    return getPointerOperand()->getType()->getPointerAddressSpace();
628  }
629
630  unsigned getDestAddressSpace() const {
631    return getType()->getPointerAddressSpace();
632  }
633};
634
635} // end namespace llvm
636
637#endif // LLVM_IR_OPERATOR_H
638