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 //===-- llvm/Instruction.h - Instruction class definition -------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file contains the declaration of the Instruction class, which is the
 // base class for all of the LLVM instructions.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_IR_INSTRUCTION_H
 #define LLVM_IR_INSTRUCTION_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Bitfields.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/ilist_node.h"
 #include "llvm/IR/DebugLoc.h"
 #include "llvm/IR/SymbolTableListTraits.h"
 #include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/AtomicOrdering.h"
 #include <cstdint>
 #include <utility>
 
 namespace llvm {
 
 class BasicBlock;
 class DataLayout;
 class DbgMarker;
 class FastMathFlags;
 class MDNode;
 class Module;
 struct AAMDNodes;
 class DbgMarker;
 class DbgRecord;
 
 template <> struct ilist_alloc_traits<Instruction> {
   static inline void deleteNode(Instruction *V);
 };
 
 iterator_range<simple_ilist<DbgRecord>::iterator>
 getDbgRecordRange(DbgMarker *);
 
 class InsertPosition {
   using InstListType = SymbolTableList<Instruction, ilist_iterator_bits<true>,
                                        ilist_parent<BasicBlock>>;
   InstListType::iterator InsertAt;
 
 public:
   InsertPosition(std::nullptr_t) : InsertAt() {}
   LLVM_DEPRECATED("Use BasicBlock::iterators for insertion instead",
                   "BasicBlock::iterator")
   InsertPosition(Instruction *InsertBefore);
   InsertPosition(BasicBlock *InsertAtEnd);
   InsertPosition(InstListType::iterator InsertAt) : InsertAt(InsertAt) {}
   operator InstListType::iterator() const { return InsertAt; }
   bool isValid() const { return InsertAt.isValid(); }
   BasicBlock *getBasicBlock() { return InsertAt.getNodeParent(); }
 };
 
 class Instruction : public User,
                     public ilist_node_with_parent<Instruction, BasicBlock,
                                                   ilist_iterator_bits<true>,
                                                   ilist_parent<BasicBlock>> {
 public:
   using InstListType = SymbolTableList<Instruction, ilist_iterator_bits<true>,
                                        ilist_parent<BasicBlock>>;
 
 private:
   DebugLoc DbgLoc;                         // 'dbg' Metadata cache.
 
   /// Relative order of this instruction in its parent basic block. Used for
   /// O(1) local dominance checks between instructions.
   mutable unsigned Order = 0;
 
 public:
   /// Optional marker recording the position for debugging information that
   /// takes effect immediately before this instruction. Null unless there is
   /// debugging information present.
   DbgMarker *DebugMarker = nullptr;
 
   /// Clone any debug-info attached to \p From onto this instruction. Used to
   /// copy debugging information from one block to another, when copying entire
   /// blocks. \see DebugProgramInstruction.h , because the ordering of
   /// DbgRecords is still important, fine grain control of which instructions
   /// are moved and where they go is necessary.
   /// \p From The instruction to clone debug-info from.
   /// \p from_here Optional iterator to limit DbgRecords cloned to be a range
   /// from
   ///    from_here to end().
   /// \p InsertAtHead Whether the cloned DbgRecords should be placed at the end
   ///    or the beginning of existing DbgRecords attached to this.
   /// \returns A range over the newly cloned DbgRecords.
   iterator_range<simple_ilist<DbgRecord>::iterator> cloneDebugInfoFrom(
       const Instruction *From,
       std::optional<simple_ilist<DbgRecord>::iterator> FromHere = std::nullopt,
       bool InsertAtHead = false);
 
   /// Return a range over the DbgRecords attached to this instruction.
   iterator_range<simple_ilist<DbgRecord>::iterator> getDbgRecordRange() const {
     return llvm::getDbgRecordRange(DebugMarker);
   }
 
   /// Return an iterator to the position of the "Next" DbgRecord after this
   /// instruction, or std::nullopt. This is the position to pass to
   /// BasicBlock::reinsertInstInDbgRecords when re-inserting an instruction.
   std::optional<simple_ilist<DbgRecord>::iterator> getDbgReinsertionPosition();
 
   /// Returns true if any DbgRecords are attached to this instruction.
   bool hasDbgRecords() const;
 
   /// Transfer any DbgRecords on the position \p It onto this instruction,
   /// by simply adopting the sequence of DbgRecords (which is efficient) if
   /// possible, by merging two sequences otherwise.
   void adoptDbgRecords(BasicBlock *BB, InstListType::iterator It,
                        bool InsertAtHead);
 
   /// Erase any DbgRecords attached to this instruction.
   void dropDbgRecords();
 
   /// Erase a single DbgRecord \p I that is attached to this instruction.
   void dropOneDbgRecord(DbgRecord *I);
 
   /// Handle the debug-info implications of this instruction being removed. Any
   /// attached DbgRecords need to "fall" down onto the next instruction.
   void handleMarkerRemoval();
 
 protected:
   // The 15 first bits of `Value::SubclassData` are available for subclasses of
   // `Instruction` to use.
   using OpaqueField = Bitfield::Element<uint16_t, 0, 15>;
 
   // Template alias so that all Instruction storing alignment use the same
   // definiton.
   // Valid alignments are powers of two from 2^0 to 2^MaxAlignmentExponent =
   // 2^32. We store them as Log2(Alignment), so we need 6 bits to encode the 33
   // possible values.
   template <unsigned Offset>
   using AlignmentBitfieldElementT =
       typename Bitfield::Element<unsigned, Offset, 6,
                                  Value::MaxAlignmentExponent>;
 
   template <unsigned Offset>
   using BoolBitfieldElementT = typename Bitfield::Element<bool, Offset, 1>;
 
   template <unsigned Offset>
   using AtomicOrderingBitfieldElementT =
       typename Bitfield::Element<AtomicOrdering, Offset, 3,
                                  AtomicOrdering::LAST>;
 
 private:
   // The last bit is used to store whether the instruction has metadata attached
   // or not.
   using HasMetadataField = Bitfield::Element<bool, 15, 1>;
 
 protected:
   ~Instruction(); // Use deleteValue() to delete a generic Instruction.
 
 public:
   Instruction(const Instruction &) = delete;
   Instruction &operator=(const Instruction &) = delete;
 
   /// Specialize the methods defined in Value, as we know that an instruction
   /// can only be used by other instructions.
   Instruction       *user_back()       { return cast<Instruction>(*user_begin());}
   const Instruction *user_back() const { return cast<Instruction>(*user_begin());}
 
   /// Return the module owning the function this instruction belongs to
   /// or nullptr it the function does not have a module.
   ///
   /// Note: this is undefined behavior if the instruction does not have a
   /// parent, or the parent basic block does not have a parent function.
   const Module *getModule() const;
   Module *getModule() {
     return const_cast<Module *>(
                            static_cast<const Instruction *>(this)->getModule());
   }
 
   /// Return the function this instruction belongs to.
   ///
   /// Note: it is undefined behavior to call this on an instruction not
   /// currently inserted into a function.
   const Function *getFunction() const;
   Function *getFunction() {
     return const_cast<Function *>(
                          static_cast<const Instruction *>(this)->getFunction());
   }
 
   /// Get the data layout of the module this instruction belongs to.
   ///
   /// Requires the instruction to have a parent module.
   const DataLayout &getDataLayout() const;
 
   /// This method unlinks 'this' from the containing basic block, but does not
   /// delete it.
   void removeFromParent();
 
   /// This method unlinks 'this' from the containing basic block and deletes it.
   ///
   /// \returns an iterator pointing to the element after the erased one
   InstListType::iterator eraseFromParent();
 
   /// Insert an unlinked instruction into a basic block immediately before
   /// the specified instruction.
   ///
   /// Deprecated in favour of the iterator-accepting flavour. Iterators at the
   /// start of a block such as BasicBlock::getFirstNonPHIIt must be passed into
   /// insertBefore without unwrapping/rewrapping. For all other positions, call
   /// getIterator to fetch the instruction iterator.
   LLVM_DEPRECATED("Use iterators as instruction positions", "")
   void insertBefore(Instruction *InsertPos);
 
   /// Insert an unlinked instruction into a basic block immediately before
   /// the specified position.
   void insertBefore(InstListType::iterator InsertPos);
 
   /// Insert an unlinked instruction into a basic block immediately after the
   /// specified instruction.
   void insertAfter(Instruction *InsertPos);
 
   /// Insert an unlinked instruction into a basic block immediately after the
   /// specified position.
   void insertAfter(InstListType::iterator InsertPos);
 
   /// Inserts an unlinked instruction into \p ParentBB at position \p It and
   /// returns the iterator of the inserted instruction.
   InstListType::iterator insertInto(BasicBlock *ParentBB,
                                     InstListType::iterator It);
 
   void insertBefore(BasicBlock &BB, InstListType::iterator InsertPos);
 
   /// Unlink this instruction from its current basic block and insert it into
   /// the basic block that MovePos lives in, right before MovePos.
   ///
   /// Deprecated in favour of the iterator-accepting flavour. Iterators at the
   /// start of a block such as BasicBlock::getFirstNonPHIIt must be passed into
   /// moveBefore without unwrapping/rewrapping. For all other positions, call
   /// getIterator to fetch the instruction iterator.
   LLVM_DEPRECATED("Use iterators as instruction positions", "")
   void moveBefore(Instruction *MovePos);
 
   /// Unlink this instruction from its current basic block and insert it into
   /// the basic block that MovePos lives in, right before MovePos.
   void moveBefore(InstListType::iterator InsertPos);
 
   /// Perform a \ref moveBefore operation, while signalling that the caller
   /// intends to preserve the original ordering of instructions. This implicitly
   /// means that any adjacent debug-info should move with this instruction.
   void moveBeforePreserving(InstListType::iterator MovePos);
 
   /// Perform a \ref moveBefore operation, while signalling that the caller
   /// intends to preserve the original ordering of instructions. This implicitly
   /// means that any adjacent debug-info should move with this instruction.
   void moveBeforePreserving(BasicBlock &BB, InstListType::iterator I);
 
   /// Perform a \ref moveBefore operation, while signalling that the caller
   /// intends to preserve the original ordering of instructions. This implicitly
   /// means that any adjacent debug-info should move with this instruction.
   ///
   /// Deprecated in favour of the iterator-accepting flavour of
   /// moveBeforePreserving, as all insertions should be at iterator positions.
   LLVM_DEPRECATED("Use iterators as instruction positions", "")
   void moveBeforePreserving(Instruction *MovePos);
 
 private:
   /// RemoveDIs project: all other moves implemented with this method,
   /// centralising debug-info updates into one place.
   void moveBeforeImpl(BasicBlock &BB, InstListType::iterator I, bool Preserve);
 
 public:
   /// Unlink this instruction and insert into BB before I.
   ///
   /// \pre I is a valid iterator into BB.
   void moveBefore(BasicBlock &BB, InstListType::iterator I);
 
   /// Unlink this instruction from its current basic block and insert it into
   /// the basic block that MovePos lives in, right after MovePos.
   void moveAfter(Instruction *MovePos);
 
   /// Unlink this instruction from its current basic block and insert it into
   /// the basic block that MovePos lives in, right after MovePos.
   void moveAfter(InstListType::iterator MovePos);
 
   /// See \ref moveBeforePreserving .
   void moveAfterPreserving(Instruction *MovePos);
 
   /// Given an instruction Other in the same basic block as this instruction,
   /// return true if this instruction comes before Other. In this worst case,
   /// this takes linear time in the number of instructions in the block. The
   /// results are cached, so in common cases when the block remains unmodified,
   /// it takes constant time.
   bool comesBefore(const Instruction *Other) const;
 
   /// Get the first insertion point at which the result of this instruction
   /// is defined. This is *not* the directly following instruction in a number
   /// of cases, e.g. phi nodes or terminators that return values. This function
   /// may return null if the insertion after the definition is not possible,
   /// e.g. due to a catchswitch terminator.
   std::optional<InstListType::iterator> getInsertionPointAfterDef();
 
   //===--------------------------------------------------------------------===//
   // Subclass classification.
   //===--------------------------------------------------------------------===//
 
   /// Returns a member of one of the enums like Instruction::Add.
   unsigned getOpcode() const { return getValueID() - InstructionVal; }
 
   const char *getOpcodeName() const { return getOpcodeName(getOpcode()); }
   bool isTerminator() const { return isTerminator(getOpcode()); }
   bool isUnaryOp() const { return isUnaryOp(getOpcode()); }
   bool isBinaryOp() const { return isBinaryOp(getOpcode()); }
   bool isIntDivRem() const { return isIntDivRem(getOpcode()); }
   bool isFPDivRem() const { return isFPDivRem(getOpcode()); }
   bool isShift() const { return isShift(getOpcode()); }
   bool isCast() const { return isCast(getOpcode()); }
   bool isFuncletPad() const { return isFuncletPad(getOpcode()); }
   bool isSpecialTerminator() const { return isSpecialTerminator(getOpcode()); }
 
   /// It checks if this instruction is the only user of at least one of
   /// its operands.
   bool isOnlyUserOfAnyOperand();
 
   static const char *getOpcodeName(unsigned Opcode);
 
   static inline bool isTerminator(unsigned Opcode) {
     return Opcode >= TermOpsBegin && Opcode < TermOpsEnd;
   }
 
   static inline bool isUnaryOp(unsigned Opcode) {
     return Opcode >= UnaryOpsBegin && Opcode < UnaryOpsEnd;
   }
   static inline bool isBinaryOp(unsigned Opcode) {
     return Opcode >= BinaryOpsBegin && Opcode < BinaryOpsEnd;
   }
 
   static inline bool isIntDivRem(unsigned Opcode) {
     return Opcode == UDiv || Opcode == SDiv || Opcode == URem || Opcode == SRem;
   }
 
   static inline bool isFPDivRem(unsigned Opcode) {
     return Opcode == FDiv || Opcode == FRem;
   }
 
   /// Determine if the Opcode is one of the shift instructions.
   static inline bool isShift(unsigned Opcode) {
     return Opcode >= Shl && Opcode <= AShr;
   }
 
   /// Return true if this is a logical shift left or a logical shift right.
   inline bool isLogicalShift() const {
     return getOpcode() == Shl || getOpcode() == LShr;
   }
 
   /// Return true if this is an arithmetic shift right.
   inline bool isArithmeticShift() const {
     return getOpcode() == AShr;
   }
 
   /// Determine if the Opcode is and/or/xor.
   static inline bool isBitwiseLogicOp(unsigned Opcode) {
     return Opcode == And || Opcode == Or || Opcode == Xor;
   }
 
   /// Return true if this is and/or/xor.
   inline bool isBitwiseLogicOp() const {
     return isBitwiseLogicOp(getOpcode());
   }
 
   /// Determine if the Opcode is one of the CastInst instructions.
   static inline bool isCast(unsigned Opcode) {
     return Opcode >= CastOpsBegin && Opcode < CastOpsEnd;
   }
 
   /// Determine if the Opcode is one of the FuncletPadInst instructions.
   static inline bool isFuncletPad(unsigned Opcode) {
     return Opcode >= FuncletPadOpsBegin && Opcode < FuncletPadOpsEnd;
   }
 
   /// Returns true if the Opcode is a "special" terminator that does more than
   /// branch to a successor (e.g. have a side effect or return a value).
   static inline bool isSpecialTerminator(unsigned Opcode) {
     switch (Opcode) {
     case Instruction::CatchSwitch:
     case Instruction::CatchRet:
     case Instruction::CleanupRet:
     case Instruction::Invoke:
     case Instruction::Resume:
     case Instruction::CallBr:
       return true;
     default:
       return false;
     }
   }
 
   //===--------------------------------------------------------------------===//
   // Metadata manipulation.
   //===--------------------------------------------------------------------===//
 
   /// Return true if this instruction has any metadata attached to it.
   bool hasMetadata() const { return DbgLoc || Value::hasMetadata(); }
 
   // Return true if this instruction contains loop metadata other than
   // a debug location
   bool hasNonDebugLocLoopMetadata() const;
 
   /// Return true if this instruction has metadata attached to it other than a
   /// debug location.
   bool hasMetadataOtherThanDebugLoc() const { return Value::hasMetadata(); }
 
   /// Return true if this instruction has the given type of metadata attached.
   bool hasMetadata(unsigned KindID) const {
     return getMetadata(KindID) != nullptr;
   }
 
   /// Return true if this instruction has the given type of metadata attached.
   bool hasMetadata(StringRef Kind) const {
     return getMetadata(Kind) != nullptr;
   }
 
   /// Get the metadata of given kind attached to this Instruction.
   /// If the metadata is not found then return null.
   MDNode *getMetadata(unsigned KindID) const {
     // Handle 'dbg' as a special case since it is not stored in the hash table.
     if (KindID == LLVMContext::MD_dbg)
       return DbgLoc.getAsMDNode();
     return Value::getMetadata(KindID);
   }
 
   /// Get the metadata of given kind attached to this Instruction.
   /// If the metadata is not found then return null.
   MDNode *getMetadata(StringRef Kind) const {
     if (!hasMetadata()) return nullptr;
     return getMetadataImpl(Kind);
   }
 
   /// Get all metadata attached to this Instruction. The first element of each
   /// pair returned is the KindID, the second element is the metadata value.
   /// This list is returned sorted by the KindID.
   void
   getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const {
     if (hasMetadata())
       getAllMetadataImpl(MDs);
   }
 
   /// This does the same thing as getAllMetadata, except that it filters out the
   /// debug location.
   void getAllMetadataOtherThanDebugLoc(
       SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const {
     Value::getAllMetadata(MDs);
   }
 
   /// Set the metadata of the specified kind to the specified node. This updates
   /// or replaces metadata if already present, or removes it if Node is null.
   void setMetadata(unsigned KindID, MDNode *Node);
   void setMetadata(StringRef Kind, MDNode *Node);
 
   /// Copy metadata from \p SrcInst to this instruction. \p WL, if not empty,
   /// specifies the list of meta data that needs to be copied. If \p WL is
   /// empty, all meta data will be copied.
   void copyMetadata(const Instruction &SrcInst,
                     ArrayRef<unsigned> WL = ArrayRef<unsigned>());
 
   /// Erase all metadata that matches the predicate.
   void eraseMetadataIf(function_ref<bool(unsigned, MDNode *)> Pred);
 
   /// If the instruction has "branch_weights" MD_prof metadata and the MDNode
   /// has three operands (including name string), swap the order of the
   /// metadata.
   void swapProfMetadata();
 
   /// Drop all unknown metadata except for debug locations.
   /// @{
   /// Passes are required to drop metadata they don't understand. This is a
   /// convenience method for passes to do so.
   /// dropUBImplyingAttrsAndUnknownMetadata should be used instead of
   /// this API if the Instruction being modified is a call.
   void dropUnknownNonDebugMetadata(ArrayRef<unsigned> KnownIDs = {});
   /// @}
 
   /// Adds an !annotation metadata node with \p Annotation to this instruction.
   /// If this instruction already has !annotation metadata, append \p Annotation
   /// to the existing node.
   void addAnnotationMetadata(StringRef Annotation);
   /// Adds an !annotation metadata node with an array of \p Annotations
   /// as a tuple to this instruction. If this instruction already has
   /// !annotation metadata, append the tuple to
   /// the existing node.
   void addAnnotationMetadata(SmallVector<StringRef> Annotations);
   /// Returns the AA metadata for this instruction.
   AAMDNodes getAAMetadata() const;
 
   /// Sets the AA metadata on this instruction from the AAMDNodes structure.
   void setAAMetadata(const AAMDNodes &N);
 
   /// Sets the nosanitize metadata on this instruction.
   void setNoSanitizeMetadata();
 
   /// Retrieve total raw weight values of a branch.
   /// Returns true on success with profile total weights filled in.
   /// Returns false if no metadata was found.
   bool extractProfTotalWeight(uint64_t &TotalVal) const;
 
   /// Set the debug location information for this instruction.
   void setDebugLoc(DebugLoc Loc) { DbgLoc = std::move(Loc); }
 
   /// Return the debug location for this node as a DebugLoc.
   const DebugLoc &getDebugLoc() const { return DbgLoc; }
 
   /// Fetch the debug location for this node, unless this is a debug intrinsic,
   /// in which case fetch the debug location of the next non-debug node.
   const DebugLoc &getStableDebugLoc() const;
 
   /// Set or clear the nuw flag on this instruction, which must be an operator
   /// which supports this flag. See LangRef.html for the meaning of this flag.
   void setHasNoUnsignedWrap(bool b = true);
 
   /// Set or clear the nsw flag on this instruction, which must be an operator
   /// which supports this flag. See LangRef.html for the meaning of this flag.
   void setHasNoSignedWrap(bool b = true);
 
   /// Set or clear the exact flag on this instruction, which must be an operator
   /// which supports this flag. See LangRef.html for the meaning of this flag.
   void setIsExact(bool b = true);
 
   /// Set or clear the nneg flag on this instruction, which must be a zext
   /// instruction.
   void setNonNeg(bool b = true);
 
   /// Determine whether the no unsigned wrap flag is set.
   bool hasNoUnsignedWrap() const LLVM_READONLY;
 
   /// Determine whether the no signed wrap flag is set.
   bool hasNoSignedWrap() const LLVM_READONLY;
 
   /// Determine whether the the nneg flag is set.
   bool hasNonNeg() const LLVM_READONLY;
 
   /// Return true if this operator has flags which may cause this instruction
   /// to evaluate to poison despite having non-poison inputs.
   bool hasPoisonGeneratingFlags() const LLVM_READONLY;
 
   /// Drops flags that may cause this instruction to evaluate to poison despite
   /// having non-poison inputs.
   void dropPoisonGeneratingFlags();
 
   /// Return true if this instruction has poison-generating metadata.
   bool hasPoisonGeneratingMetadata() const LLVM_READONLY;
 
   /// Drops metadata that may generate poison.
   void dropPoisonGeneratingMetadata();
 
   /// Return true if this instruction has poison-generating attribute.
   bool hasPoisonGeneratingReturnAttributes() const LLVM_READONLY;
 
   /// Drops return attributes that may generate poison.
   void dropPoisonGeneratingReturnAttributes();
 
   /// Return true if this instruction has poison-generating flags,
   /// return attributes or metadata.
   bool hasPoisonGeneratingAnnotations() const {
     return hasPoisonGeneratingFlags() ||
            hasPoisonGeneratingReturnAttributes() ||
            hasPoisonGeneratingMetadata();
   }
 
   /// Drops flags, return attributes and metadata that may generate poison.
   void dropPoisonGeneratingAnnotations() {
     dropPoisonGeneratingFlags();
     dropPoisonGeneratingReturnAttributes();
     dropPoisonGeneratingMetadata();
   }
 
   /// This function drops non-debug unknown metadata (through
   /// dropUnknownNonDebugMetadata). For calls, it also drops parameter and
   /// return attributes that can cause undefined behaviour. Both of these should
   /// be done by passes which move instructions in IR.
   void dropUBImplyingAttrsAndUnknownMetadata(ArrayRef<unsigned> KnownIDs = {});
 
   /// Drop any attributes or metadata that can cause immediate undefined
   /// behavior. Retain other attributes/metadata on a best-effort basis.
   /// This should be used when speculating instructions.
   void dropUBImplyingAttrsAndMetadata();
 
   /// Determine whether the exact flag is set.
   bool isExact() const LLVM_READONLY;
 
   /// Set or clear all fast-math-flags on this instruction, which must be an
   /// operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setFast(bool B);
 
   /// Set or clear the reassociation flag on this instruction, which must be
   /// an operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setHasAllowReassoc(bool B);
 
   /// Set or clear the no-nans flag on this instruction, which must be an
   /// operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setHasNoNaNs(bool B);
 
   /// Set or clear the no-infs flag on this instruction, which must be an
   /// operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setHasNoInfs(bool B);
 
   /// Set or clear the no-signed-zeros flag on this instruction, which must be
   /// an operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setHasNoSignedZeros(bool B);
 
   /// Set or clear the allow-reciprocal flag on this instruction, which must be
   /// an operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setHasAllowReciprocal(bool B);
 
   /// Set or clear the allow-contract flag on this instruction, which must be
   /// an operator which supports this flag. See LangRef.html for the meaning of
   /// this flag.
   void setHasAllowContract(bool B);
 
   /// Set or clear the approximate-math-functions flag on this instruction,
   /// which must be an operator which supports this flag. See LangRef.html for
   /// the meaning of this flag.
   void setHasApproxFunc(bool B);
 
   /// Convenience function for setting multiple fast-math flags on this
   /// instruction, which must be an operator which supports these flags. See
   /// LangRef.html for the meaning of these flags.
   void setFastMathFlags(FastMathFlags FMF);
 
   /// Convenience function for transferring all fast-math flag values to this
   /// instruction, which must be an operator which supports these flags. See
   /// LangRef.html for the meaning of these flags.
   void copyFastMathFlags(FastMathFlags FMF);
 
   /// Determine whether all fast-math-flags are set.
   bool isFast() const LLVM_READONLY;
 
   /// Determine whether the allow-reassociation flag is set.
   bool hasAllowReassoc() const LLVM_READONLY;
 
   /// Determine whether the no-NaNs flag is set.
   bool hasNoNaNs() const LLVM_READONLY;
 
   /// Determine whether the no-infs flag is set.
   bool hasNoInfs() const LLVM_READONLY;
 
   /// Determine whether the no-signed-zeros flag is set.
   bool hasNoSignedZeros() const LLVM_READONLY;
 
   /// Determine whether the allow-reciprocal flag is set.
   bool hasAllowReciprocal() const LLVM_READONLY;
 
   /// Determine whether the allow-contract flag is set.
   bool hasAllowContract() const LLVM_READONLY;
 
   /// Determine whether the approximate-math-functions flag is set.
   bool hasApproxFunc() const LLVM_READONLY;
 
   /// Convenience function for getting all the fast-math flags, which must be an
   /// operator which supports these flags. See LangRef.html for the meaning of
   /// these flags.
   FastMathFlags getFastMathFlags() const LLVM_READONLY;
 
   /// Copy I's fast-math flags
   void copyFastMathFlags(const Instruction *I);
 
   /// Convenience method to copy supported exact, fast-math, and (optionally)
   /// wrapping flags from V to this instruction.
   void copyIRFlags(const Value *V, bool IncludeWrapFlags = true);
 
   /// Logical 'and' of any supported wrapping, exact, and fast-math flags of
   /// V and this instruction.
   void andIRFlags(const Value *V);
 
   /// Merge 2 debug locations and apply it to the Instruction. If the
   /// instruction is a CallIns, we need to traverse the inline chain to find
   /// the common scope. This is not efficient for N-way merging as each time
   /// you merge 2 iterations, you need to rebuild the hashmap to find the
   /// common scope. However, we still choose this API because:
   ///  1) Simplicity: it takes 2 locations instead of a list of locations.
   ///  2) In worst case, it increases the complexity from O(N*I) to
   ///     O(2*N*I), where N is # of Instructions to merge, and I is the
   ///     maximum level of inline stack. So it is still linear.
   ///  3) Merging of call instructions should be extremely rare in real
   ///     applications, thus the N-way merging should be in code path.
   /// The DebugLoc attached to this instruction will be overwritten by the
   /// merged DebugLoc.
   void applyMergedLocation(DILocation *LocA, DILocation *LocB);
 
   /// Updates the debug location given that the instruction has been hoisted
   /// from a block to a predecessor of that block.
   /// Note: it is undefined behavior to call this on an instruction not
   /// currently inserted into a function.
   void updateLocationAfterHoist();
 
   /// Drop the instruction's debug location. This does not guarantee removal
   /// of the !dbg source location attachment, as it must set a line 0 location
   /// with scope information attached on call instructions. To guarantee
   /// removal of the !dbg attachment, use the \ref setDebugLoc() API.
   /// Note: it is undefined behavior to call this on an instruction not
   /// currently inserted into a function.
   void dropLocation();
 
   /// Merge the DIAssignID metadata from this instruction and those attached to
   /// instructions in \p SourceInstructions. This process performs a RAUW on
   /// the MetadataAsValue uses of the merged DIAssignID nodes. Not every
   /// instruction in \p SourceInstructions needs to have DIAssignID
   /// metadata. If none of them do then nothing happens. If this instruction
   /// does not have a DIAssignID attachment but at least one in \p
   /// SourceInstructions does then the merged one will be attached to
   /// it. However, instructions without attachments in \p SourceInstructions
   /// are not modified.
   void mergeDIAssignID(ArrayRef<const Instruction *> SourceInstructions);
 
 private:
   // These are all implemented in Metadata.cpp.
   MDNode *getMetadataImpl(StringRef Kind) const;
   void
   getAllMetadataImpl(SmallVectorImpl<std::pair<unsigned, MDNode *>> &) const;
 
   /// Update the LLVMContext ID-to-Instruction(s) mapping. If \p ID is nullptr
   /// then clear the mapping for this instruction.
   void updateDIAssignIDMapping(DIAssignID *ID);
 
 public:
   //===--------------------------------------------------------------------===//
   // Predicates and helper methods.
   //===--------------------------------------------------------------------===//
 
   /// Return true if the instruction is associative:
   ///
   ///   Associative operators satisfy:  x op (y op z) === (x op y) op z
   ///
   /// In LLVM, the Add, Mul, And, Or, and Xor operators are associative.
   ///
   bool isAssociative() const LLVM_READONLY;
   static bool isAssociative(unsigned Opcode) {
     return Opcode == And || Opcode == Or || Opcode == Xor ||
            Opcode == Add || Opcode == Mul;
   }
 
   /// Return true if the instruction is commutative:
   ///
   ///   Commutative operators satisfy: (x op y) === (y op x)
   ///
   /// In LLVM, these are the commutative operators, plus SetEQ and SetNE, when
   /// applied to any type.
   ///
   bool isCommutative() const LLVM_READONLY;
   static bool isCommutative(unsigned Opcode) {
     switch (Opcode) {
     case Add: case FAdd:
     case Mul: case FMul:
     case And: case Or: case Xor:
       return true;
     default:
       return false;
   }
   }
 
   /// Return true if the instruction is idempotent:
   ///
   ///   Idempotent operators satisfy:  x op x === x
   ///
   /// In LLVM, the And and Or operators are idempotent.
   ///
   bool isIdempotent() const { return isIdempotent(getOpcode()); }
   static bool isIdempotent(unsigned Opcode) {
     return Opcode == And || Opcode == Or;
   }
 
   /// Return true if the instruction is nilpotent:
   ///
   ///   Nilpotent operators satisfy:  x op x === Id,
   ///
   ///   where Id is the identity for the operator, i.e. a constant such that
   ///     x op Id === x and Id op x === x for all x.
   ///
   /// In LLVM, the Xor operator is nilpotent.
   ///
   bool isNilpotent() const { return isNilpotent(getOpcode()); }
   static bool isNilpotent(unsigned Opcode) {
     return Opcode == Xor;
   }
 
   /// Return true if this instruction may modify memory.
   bool mayWriteToMemory() const LLVM_READONLY;
 
   /// Return true if this instruction may read memory.
   bool mayReadFromMemory() const LLVM_READONLY;
 
   /// Return true if this instruction may read or write memory.
   bool mayReadOrWriteMemory() const {
     return mayReadFromMemory() || mayWriteToMemory();
   }
 
   /// Return true if this instruction has an AtomicOrdering of unordered or
   /// higher.
   bool isAtomic() const LLVM_READONLY;
 
   /// Return true if this atomic instruction loads from memory.
   bool hasAtomicLoad() const LLVM_READONLY;
 
   /// Return true if this atomic instruction stores to memory.
   bool hasAtomicStore() const LLVM_READONLY;
 
   /// Return true if this instruction has a volatile memory access.
   bool isVolatile() const LLVM_READONLY;
 
   /// Return the type this instruction accesses in memory, if any.
   Type *getAccessType() const LLVM_READONLY;
 
   /// Return true if this instruction may throw an exception.
   ///
   /// If IncludePhaseOneUnwind is set, this will also include cases where
   /// phase one unwinding may unwind past this frame due to skipping of
   /// cleanup landingpads.
   bool mayThrow(bool IncludePhaseOneUnwind = false) const LLVM_READONLY;
 
   /// Return true if this instruction behaves like a memory fence: it can load
   /// or store to memory location without being given a memory location.
   bool isFenceLike() const {
     switch (getOpcode()) {
     default:
       return false;
     // This list should be kept in sync with the list in mayWriteToMemory for
     // all opcodes which don't have a memory location.
     case Instruction::Fence:
     case Instruction::CatchPad:
     case Instruction::CatchRet:
     case Instruction::Call:
     case Instruction::Invoke:
       return true;
     }
   }
 
   /// Return true if the instruction may have side effects.
   ///
   /// Side effects are:
   ///  * Writing to memory.
   ///  * Unwinding.
   ///  * Not returning (e.g. an infinite loop).
   ///
   /// Note that this does not consider malloc and alloca to have side
   /// effects because the newly allocated memory is completely invisible to
   /// instructions which don't use the returned value.  For cases where this
   /// matters, isSafeToSpeculativelyExecute may be more appropriate.
   bool mayHaveSideEffects() const LLVM_READONLY;
 
   /// Return true if the instruction can be removed if the result is unused.
   ///
   /// When constant folding some instructions cannot be removed even if their
   /// results are unused. Specifically terminator instructions and calls that
   /// may have side effects cannot be removed without semantically changing the
   /// generated program.
   bool isSafeToRemove() const LLVM_READONLY;
 
   /// Return true if the instruction will return (unwinding is considered as
   /// a form of returning control flow here).
   bool willReturn() const LLVM_READONLY;
 
   /// Return true if the instruction is a variety of EH-block.
   bool isEHPad() const {
     switch (getOpcode()) {
     case Instruction::CatchSwitch:
     case Instruction::CatchPad:
     case Instruction::CleanupPad:
     case Instruction::LandingPad:
       return true;
     default:
       return false;
     }
   }
 
   /// Return true if the instruction is a llvm.lifetime.start or
   /// llvm.lifetime.end marker.
   bool isLifetimeStartOrEnd() const LLVM_READONLY;
 
   /// Return true if the instruction is a llvm.launder.invariant.group or
   /// llvm.strip.invariant.group.
   bool isLaunderOrStripInvariantGroup() const LLVM_READONLY;
 
   /// Return true if the instruction is a DbgInfoIntrinsic or PseudoProbeInst.
   bool isDebugOrPseudoInst() const LLVM_READONLY;
 
   /// Return a pointer to the next non-debug instruction in the same basic
   /// block as 'this', or nullptr if no such instruction exists. Skip any pseudo
   /// operations if \c SkipPseudoOp is true.
   const Instruction *
   getNextNonDebugInstruction(bool SkipPseudoOp = false) const;
   Instruction *getNextNonDebugInstruction(bool SkipPseudoOp = false) {
     return const_cast<Instruction *>(
         static_cast<const Instruction *>(this)->getNextNonDebugInstruction(
             SkipPseudoOp));
   }
 
   /// Return a pointer to the previous non-debug instruction in the same basic
   /// block as 'this', or nullptr if no such instruction exists. Skip any pseudo
   /// operations if \c SkipPseudoOp is true.
   const Instruction *
   getPrevNonDebugInstruction(bool SkipPseudoOp = false) const;
   Instruction *getPrevNonDebugInstruction(bool SkipPseudoOp = false) {
     return const_cast<Instruction *>(
         static_cast<const Instruction *>(this)->getPrevNonDebugInstruction(
             SkipPseudoOp));
   }
 
   /// Create a copy of 'this' instruction that is identical in all ways except
   /// the following:
   ///   * The instruction has no parent
   ///   * The instruction has no name
   ///
   Instruction *clone() const;
 
   /// Return true if the specified instruction is exactly identical to the
   /// current one. This means that all operands match and any extra information
   /// (e.g. load is volatile) agree.
   bool isIdenticalTo(const Instruction *I) const LLVM_READONLY;
 
   /// This is like isIdenticalTo, except that it ignores the
   /// SubclassOptionalData flags, which may specify conditions under which the
   /// instruction's result is undefined.
   bool
   isIdenticalToWhenDefined(const Instruction *I,
                            bool IntersectAttrs = false) const LLVM_READONLY;
 
   /// When checking for operation equivalence (using isSameOperationAs) it is
   /// sometimes useful to ignore certain attributes.
   enum OperationEquivalenceFlags {
     /// Check for equivalence ignoring load/store alignment.
     CompareIgnoringAlignment = 1 << 0,
     /// Check for equivalence treating a type and a vector of that type
     /// as equivalent.
     CompareUsingScalarTypes = 1 << 1,
     /// Check for equivalence with intersected callbase attrs.
     CompareUsingIntersectedAttrs = 1 << 2,
   };
 
   /// This function determines if the specified instruction executes the same
   /// operation as the current one. This means that the opcodes, type, operand
   /// types and any other factors affecting the operation must be the same. This
   /// is similar to isIdenticalTo except the operands themselves don't have to
   /// be identical.
   /// @returns true if the specified instruction is the same operation as
   /// the current one.
   /// Determine if one instruction is the same operation as another.
   bool isSameOperationAs(const Instruction *I, unsigned flags = 0) const LLVM_READONLY;
 
   /// This function determines if the speficied instruction has the same
   /// "special" characteristics as the current one. This means that opcode
   /// specific details are the same. As a common example, if we are comparing
   /// loads, then hasSameSpecialState would compare the alignments (among
   /// other things).
   /// @returns true if the specific instruction has the same opcde specific
   /// characteristics as the current one. Determine if one instruction has the
   /// same state as another.
   bool hasSameSpecialState(const Instruction *I2, bool IgnoreAlignment = false,
                            bool IntersectAttrs = false) const LLVM_READONLY;
 
   /// Return true if there are any uses of this instruction in blocks other than
   /// the specified block. Note that PHI nodes are considered to evaluate their
   /// operands in the corresponding predecessor block.
   bool isUsedOutsideOfBlock(const BasicBlock *BB) const LLVM_READONLY;
 
   /// Return the number of successors that this instruction has. The instruction
   /// must be a terminator.
   unsigned getNumSuccessors() const LLVM_READONLY;
 
   /// Return the specified successor. This instruction must be a terminator.
   BasicBlock *getSuccessor(unsigned Idx) const LLVM_READONLY;
 
   /// Update the specified successor to point at the provided block. This
   /// instruction must be a terminator.
   void setSuccessor(unsigned Idx, BasicBlock *BB);
 
   /// Replace specified successor OldBB to point at the provided block.
   /// This instruction must be a terminator.
   void replaceSuccessorWith(BasicBlock *OldBB, BasicBlock *NewBB);
 
   /// Methods for support type inquiry through isa, cast, and dyn_cast:
   static bool classof(const Value *V) {
     return V->getValueID() >= Value::InstructionVal;
   }
 
   //----------------------------------------------------------------------
   // Exported enumerations.
   //
   enum TermOps {       // These terminate basic blocks
 #define  FIRST_TERM_INST(N)             TermOpsBegin = N,
 #define HANDLE_TERM_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_TERM_INST(N)             TermOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
   enum UnaryOps {
 #define  FIRST_UNARY_INST(N)             UnaryOpsBegin = N,
 #define HANDLE_UNARY_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_UNARY_INST(N)             UnaryOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
   enum BinaryOps {
 #define  FIRST_BINARY_INST(N)             BinaryOpsBegin = N,
 #define HANDLE_BINARY_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_BINARY_INST(N)             BinaryOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
   enum MemoryOps {
 #define  FIRST_MEMORY_INST(N)             MemoryOpsBegin = N,
 #define HANDLE_MEMORY_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_MEMORY_INST(N)             MemoryOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
   enum CastOps {
 #define  FIRST_CAST_INST(N)             CastOpsBegin = N,
 #define HANDLE_CAST_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_CAST_INST(N)             CastOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
   enum FuncletPadOps {
 #define  FIRST_FUNCLETPAD_INST(N)             FuncletPadOpsBegin = N,
 #define HANDLE_FUNCLETPAD_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_FUNCLETPAD_INST(N)             FuncletPadOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
   enum OtherOps {
 #define  FIRST_OTHER_INST(N)             OtherOpsBegin = N,
 #define HANDLE_OTHER_INST(N, OPC, CLASS) OPC = N,
 #define   LAST_OTHER_INST(N)             OtherOpsEnd = N+1
 #include "llvm/IR/Instruction.def"
   };
 
 private:
   friend class SymbolTableListTraits<Instruction, ilist_iterator_bits<true>,
                                      ilist_parent<BasicBlock>>;
   friend class BasicBlock; // For renumbering.
 
   // Shadow Value::setValueSubclassData with a private forwarding method so that
   // subclasses cannot accidentally use it.
   void setValueSubclassData(unsigned short D) {
     Value::setValueSubclassData(D);
   }
 
   unsigned short getSubclassDataFromValue() const {
     return Value::getSubclassDataFromValue();
   }
 
 protected:
   // Instruction subclasses can stick up to 15 bits of stuff into the
   // SubclassData field of instruction with these members.
 
   template <typename BitfieldElement>
   typename BitfieldElement::Type getSubclassData() const {
     static_assert(
         std::is_same<BitfieldElement, HasMetadataField>::value ||
             !Bitfield::isOverlapping<BitfieldElement, HasMetadataField>(),
         "Must not overlap with the metadata bit");
     return Bitfield::get<BitfieldElement>(getSubclassDataFromValue());
   }
 
   template <typename BitfieldElement>
   void setSubclassData(typename BitfieldElement::Type Value) {
     static_assert(
         std::is_same<BitfieldElement, HasMetadataField>::value ||
             !Bitfield::isOverlapping<BitfieldElement, HasMetadataField>(),
         "Must not overlap with the metadata bit");
     auto Storage = getSubclassDataFromValue();
     Bitfield::set<BitfieldElement>(Storage, Value);
     setValueSubclassData(Storage);
   }
 
   Instruction(Type *Ty, unsigned iType, AllocInfo AllocInfo,
               InsertPosition InsertBefore = nullptr);
 
 private:
   /// Create a copy of this instruction.
   Instruction *cloneImpl() const;
 };
 
 inline void ilist_alloc_traits<Instruction>::deleteNode(Instruction *V) {
   V->deleteValue();
 }
 
 } // end namespace llvm
 
 #endif // LLVM_IR_INSTRUCTION_H

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