EIC code displayed by LXR master/​include/​llvm/​IR/​BasicBlock.h	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2026-05-10 08:43:57

 //===- llvm/BasicBlock.h - Represent a basic block in the VM ----*- 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 BasicBlock class.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_IR_BASICBLOCK_H
 #define LLVM_IR_BASICBLOCK_H
 
 #include "llvm-c/Types.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/ilist.h"
 #include "llvm/ADT/ilist_node.h"
 #include "llvm/ADT/iterator.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/IR/DebugProgramInstruction.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/SymbolTableListTraits.h"
 #include "llvm/IR/Value.h"
 #include <cassert>
 #include <cstddef>
 #include <iterator>
 
 namespace llvm {
 
 class AssemblyAnnotationWriter;
 class CallInst;
 class DataLayout;
 class Function;
 class LandingPadInst;
 class LLVMContext;
 class Module;
 class PHINode;
 class ValueSymbolTable;
 class DbgVariableRecord;
 class DbgMarker;
 
 /// LLVM Basic Block Representation
 ///
 /// This represents a single basic block in LLVM. A basic block is simply a
 /// container of instructions that execute sequentially. Basic blocks are Values
 /// because they are referenced by instructions such as branches and switch
 /// tables. The type of a BasicBlock is "Type::LabelTy" because the basic block
 /// represents a label to which a branch can jump.
 ///
 /// A well formed basic block is formed of a list of non-terminating
 /// instructions followed by a single terminator instruction. Terminator
 /// instructions may not occur in the middle of basic blocks, and must terminate
 /// the blocks. The BasicBlock class allows malformed basic blocks to occur
 /// because it may be useful in the intermediate stage of constructing or
 /// modifying a program. However, the verifier will ensure that basic blocks are
 /// "well formed".
 class BasicBlock final : public Value, // Basic blocks are data objects also
                          public ilist_node_with_parent<BasicBlock, Function> {
 public:
   using InstListType = SymbolTableList<Instruction, ilist_iterator_bits<true>,
                                        ilist_parent<BasicBlock>>;
   /// Flag recording whether or not this block stores debug-info in the form
   /// of intrinsic instructions (false) or non-instruction records (true).
   bool IsNewDbgInfoFormat;
 
 private:
   // Allow Function to renumber blocks.
   friend class Function;
   /// Per-function unique number.
   unsigned Number = -1u;
 
   friend class BlockAddress;
   friend class SymbolTableListTraits<BasicBlock>;
 
   InstListType InstList;
   Function *Parent;
 
 public:
   /// Attach a DbgMarker to the given instruction. Enables the storage of any
   /// debug-info at this position in the program.
   DbgMarker *createMarker(Instruction *I);
   DbgMarker *createMarker(InstListType::iterator It);
 
   /// Convert variable location debugging information stored in dbg.value
   /// intrinsics into DbgMarkers / DbgRecords. Deletes all dbg.values in
   /// the process and sets IsNewDbgInfoFormat = true. Only takes effect if
   /// the UseNewDbgInfoFormat LLVM command line option is given.
   void convertToNewDbgValues();
 
   /// Convert variable location debugging information stored in DbgMarkers and
   /// DbgRecords into the dbg.value intrinsic representation. Sets
   /// IsNewDbgInfoFormat = false.
   void convertFromNewDbgValues();
 
   /// Ensure the block is in "old" dbg.value format (\p NewFlag == false) or
   /// in the new format (\p NewFlag == true), converting to the desired format
   /// if necessary.
   void setIsNewDbgInfoFormat(bool NewFlag);
   void setNewDbgInfoFormatFlag(bool NewFlag);
 
   unsigned getNumber() const {
     assert(getParent() && "only basic blocks in functions have valid numbers");
     return Number;
   }
 
   /// Record that the collection of DbgRecords in \p M "trails" after the last
   /// instruction of this block. These are equivalent to dbg.value intrinsics
   /// that exist at the end of a basic block with no terminator (a transient
   /// state that occurs regularly).
   void setTrailingDbgRecords(DbgMarker *M);
 
   /// Fetch the collection of DbgRecords that "trail" after the last instruction
   /// of this block, see \ref setTrailingDbgRecords. If there are none, returns
   /// nullptr.
   DbgMarker *getTrailingDbgRecords();
 
   /// Delete any trailing DbgRecords at the end of this block, see
   /// \ref setTrailingDbgRecords.
   void deleteTrailingDbgRecords();
 
   void dumpDbgValues() const;
 
   /// Return the DbgMarker for the position given by \p It, so that DbgRecords
   /// can be inserted there. This will either be nullptr if not present, a
   /// DbgMarker, or TrailingDbgRecords if It is end().
   DbgMarker *getMarker(InstListType::iterator It);
 
   /// Return the DbgMarker for the position that comes after \p I. \see
   /// BasicBlock::getMarker, this can be nullptr, a DbgMarker, or
   /// TrailingDbgRecords if there is no next instruction.
   DbgMarker *getNextMarker(Instruction *I);
 
   /// Insert a DbgRecord into a block at the position given by \p I.
   void insertDbgRecordAfter(DbgRecord *DR, Instruction *I);
 
   /// Insert a DbgRecord into a block at the position given by \p Here.
   void insertDbgRecordBefore(DbgRecord *DR, InstListType::iterator Here);
 
   /// Eject any debug-info trailing at the end of a block. DbgRecords can
   /// transiently be located "off the end" of a block if the blocks terminator
   /// is temporarily removed. Once a terminator is re-inserted this method will
   /// move such DbgRecords back to the right place (ahead of the terminator).
   void flushTerminatorDbgRecords();
 
   /// In rare circumstances instructions can be speculatively removed from
   /// blocks, and then be re-inserted back into that position later. When this
   /// happens in RemoveDIs debug-info mode, some special patching-up needs to
   /// occur: inserting into the middle of a sequence of dbg.value intrinsics
   /// does not have an equivalent with DbgRecords.
   void reinsertInstInDbgRecords(Instruction *I,
                                 std::optional<DbgRecord::self_iterator> Pos);
 
 private:
   void setParent(Function *parent);
 
   /// Constructor.
   ///
   /// If the function parameter is specified, the basic block is automatically
   /// inserted at either the end of the function (if InsertBefore is null), or
   /// before the specified basic block.
   explicit BasicBlock(LLVMContext &C, const Twine &Name = "",
                       Function *Parent = nullptr,
                       BasicBlock *InsertBefore = nullptr);
 
 public:
   BasicBlock(const BasicBlock &) = delete;
   BasicBlock &operator=(const BasicBlock &) = delete;
   ~BasicBlock();
 
   /// Get the context in which this basic block lives.
   LLVMContext &getContext() const;
 
   /// Instruction iterators...
   using iterator = InstListType::iterator;
   using const_iterator = InstListType::const_iterator;
   using reverse_iterator = InstListType::reverse_iterator;
   using const_reverse_iterator = InstListType::const_reverse_iterator;
 
   // These functions and classes need access to the instruction list.
   friend void Instruction::removeFromParent();
   friend BasicBlock::iterator Instruction::eraseFromParent();
   friend BasicBlock::iterator Instruction::insertInto(BasicBlock *BB,
                                                       BasicBlock::iterator It);
   friend class llvm::SymbolTableListTraits<
       llvm::Instruction, ilist_iterator_bits<true>, ilist_parent<BasicBlock>>;
   friend class llvm::ilist_node_with_parent<llvm::Instruction, llvm::BasicBlock,
                                             ilist_iterator_bits<true>,
                                             ilist_parent<BasicBlock>>;
 
   // Friendly methods that need to access us for the maintenence of
   // debug-info attachments.
   friend void Instruction::insertBefore(BasicBlock::iterator InsertPos);
   friend void Instruction::insertAfter(Instruction *InsertPos);
   friend void Instruction::insertAfter(BasicBlock::iterator InsertPos);
   friend void Instruction::insertBefore(BasicBlock &BB,
                                         InstListType::iterator InsertPos);
   friend void Instruction::moveBeforeImpl(BasicBlock &BB,
                                           InstListType::iterator I,
                                           bool Preserve);
   friend iterator_range<DbgRecord::self_iterator>
   Instruction::cloneDebugInfoFrom(
       const Instruction *From, std::optional<DbgRecord::self_iterator> FromHere,
       bool InsertAtHead);
 
   /// Creates a new BasicBlock.
   ///
   /// If the Parent parameter is specified, the basic block is automatically
   /// inserted at either the end of the function (if InsertBefore is 0), or
   /// before the specified basic block.
   static BasicBlock *Create(LLVMContext &Context, const Twine &Name = "",
                             Function *Parent = nullptr,
                             BasicBlock *InsertBefore = nullptr) {
     return new BasicBlock(Context, Name, Parent, InsertBefore);
   }
 
   /// Return the enclosing method, or null if none.
   const Function *getParent() const { return Parent; }
         Function *getParent()       { return Parent; }
 
   /// Return the module owning the function this basic block belongs to, or
   /// nullptr if the function does not have a module.
   ///
   /// Note: this is undefined behavior if the block does not have a parent.
   const Module *getModule() const;
   Module *getModule() {
     return const_cast<Module *>(
                             static_cast<const BasicBlock *>(this)->getModule());
   }
 
   /// Get the data layout of the module this basic block belongs to.
   ///
   /// Requires the basic block to have a parent module.
   const DataLayout &getDataLayout() const;
 
   /// Returns the terminator instruction if the block is well formed or null
   /// if the block is not well formed.
   const Instruction *getTerminator() const LLVM_READONLY {
     if (InstList.empty() || !InstList.back().isTerminator())
       return nullptr;
     return &InstList.back();
   }
   Instruction *getTerminator() {
     return const_cast<Instruction *>(
         static_cast<const BasicBlock *>(this)->getTerminator());
   }
 
   /// Returns the call instruction calling \@llvm.experimental.deoptimize
   /// prior to the terminating return instruction of this basic block, if such
   /// a call is present.  Otherwise, returns null.
   const CallInst *getTerminatingDeoptimizeCall() const;
   CallInst *getTerminatingDeoptimizeCall() {
     return const_cast<CallInst *>(
          static_cast<const BasicBlock *>(this)->getTerminatingDeoptimizeCall());
   }
 
   /// Returns the call instruction calling \@llvm.experimental.deoptimize
   /// that is present either in current basic block or in block that is a unique
   /// successor to current block, if such call is present. Otherwise, returns null.
   const CallInst *getPostdominatingDeoptimizeCall() const;
   CallInst *getPostdominatingDeoptimizeCall() {
     return const_cast<CallInst *>(
          static_cast<const BasicBlock *>(this)->getPostdominatingDeoptimizeCall());
   }
 
   /// Returns the call instruction marked 'musttail' prior to the terminating
   /// return instruction of this basic block, if such a call is present.
   /// Otherwise, returns null.
   const CallInst *getTerminatingMustTailCall() const;
   CallInst *getTerminatingMustTailCall() {
     return const_cast<CallInst *>(
            static_cast<const BasicBlock *>(this)->getTerminatingMustTailCall());
   }
 
   /// Returns a pointer to the first instruction in this block that is not a
   /// PHINode instruction.
   ///
   /// When adding instructions to the beginning of the basic block, they should
   /// be added before the returned value, not before the first instruction,
   /// which might be PHI. Returns 0 is there's no non-PHI instruction.
   ///
   /// Deprecated in favour of getFirstNonPHIIt, which returns an iterator that
   /// preserves some debugging information.
   LLVM_DEPRECATED("Use iterators as instruction positions", "getFirstNonPHIIt")
   const Instruction *getFirstNonPHI() const;
   LLVM_DEPRECATED("Use iterators as instruction positions instead",
                   "getFirstNonPHIIt")
   Instruction *getFirstNonPHI();
 
   /// Returns an iterator to the first instruction in this block that is not a
   /// PHINode instruction.
   ///
   /// When adding instructions to the beginning of the basic block, they should
   /// be added before the returned value, not before the first instruction,
   /// which might be PHI. Returns end() if there's no non-PHI instruction.
   ///
   /// Avoid unwrapping the iterator to an Instruction* before inserting here,
   /// as important debug-info is preserved in the iterator.
   InstListType::const_iterator getFirstNonPHIIt() const;
   InstListType::iterator getFirstNonPHIIt() {
     BasicBlock::iterator It =
         static_cast<const BasicBlock *>(this)->getFirstNonPHIIt().getNonConst();
     It.setHeadBit(true);
     return It;
   }
 
   /// Returns a pointer to the first instruction in this block that is not a
   /// PHINode or a debug intrinsic, or any pseudo operation if \c SkipPseudoOp
   /// is true.
   InstListType::const_iterator
   getFirstNonPHIOrDbg(bool SkipPseudoOp = true) const;
   InstListType::iterator getFirstNonPHIOrDbg(bool SkipPseudoOp = true) {
     return static_cast<const BasicBlock *>(this)
         ->getFirstNonPHIOrDbg(SkipPseudoOp)
         .getNonConst();
   }
 
   /// Returns a pointer to the first instruction in this block that is not a
   /// PHINode, a debug intrinsic, or a lifetime intrinsic, or any pseudo
   /// operation if \c SkipPseudoOp is true.
   InstListType::const_iterator
   getFirstNonPHIOrDbgOrLifetime(bool SkipPseudoOp = true) const;
   InstListType::iterator
   getFirstNonPHIOrDbgOrLifetime(bool SkipPseudoOp = true) {
     return static_cast<const BasicBlock *>(this)
         ->getFirstNonPHIOrDbgOrLifetime(SkipPseudoOp)
         .getNonConst();
   }
 
   /// Returns an iterator to the first instruction in this block that is
   /// suitable for inserting a non-PHI instruction.
   ///
   /// In particular, it skips all PHIs and LandingPad instructions.
   const_iterator getFirstInsertionPt() const;
   iterator getFirstInsertionPt() {
     return static_cast<const BasicBlock *>(this)
                                           ->getFirstInsertionPt().getNonConst();
   }
 
   /// Returns an iterator to the first instruction in this block that is
   /// not a PHINode, a debug intrinsic, a static alloca or any pseudo operation.
   const_iterator getFirstNonPHIOrDbgOrAlloca() const;
   iterator getFirstNonPHIOrDbgOrAlloca() {
     return static_cast<const BasicBlock *>(this)
         ->getFirstNonPHIOrDbgOrAlloca()
         .getNonConst();
   }
 
   /// Returns the first potential AsynchEH faulty instruction
   /// currently it checks for loads/stores (which may dereference a null
   /// pointer) and calls/invokes (which may propagate exceptions)
   const Instruction* getFirstMayFaultInst() const;
   Instruction* getFirstMayFaultInst() {
       return const_cast<Instruction*>(
           static_cast<const BasicBlock*>(this)->getFirstMayFaultInst());
   }
 
   /// Return a const iterator range over the instructions in the block, skipping
   /// any debug instructions. Skip any pseudo operations as well if \c
   /// SkipPseudoOp is true.
   iterator_range<filter_iterator<BasicBlock::const_iterator,
                                  std::function<bool(const Instruction &)>>>
   instructionsWithoutDebug(bool SkipPseudoOp = true) const;
 
   /// Return an iterator range over the instructions in the block, skipping any
   /// debug instructions. Skip and any pseudo operations as well if \c
   /// SkipPseudoOp is true.
   iterator_range<
       filter_iterator<BasicBlock::iterator, std::function<bool(Instruction &)>>>
   instructionsWithoutDebug(bool SkipPseudoOp = true);
 
   /// Return the size of the basic block ignoring debug instructions
   filter_iterator<BasicBlock::const_iterator,
                   std::function<bool(const Instruction &)>>::difference_type
   sizeWithoutDebug() const;
 
   /// Unlink 'this' from the containing function, but do not delete it.
   void removeFromParent();
 
   /// Unlink 'this' from the containing function and delete it.
   ///
   // \returns an iterator pointing to the element after the erased one.
   SymbolTableList<BasicBlock>::iterator eraseFromParent();
 
   /// Unlink this basic block from its current function and insert it into
   /// the function that \p MovePos lives in, right before \p MovePos.
   inline void moveBefore(BasicBlock *MovePos) {
     moveBefore(MovePos->getIterator());
   }
   void moveBefore(SymbolTableList<BasicBlock>::iterator MovePos);
 
   /// Unlink this basic block from its current function and insert it
   /// right after \p MovePos in the function \p MovePos lives in.
   void moveAfter(BasicBlock *MovePos);
 
   /// Insert unlinked basic block into a function.
   ///
   /// Inserts an unlinked basic block into \c Parent.  If \c InsertBefore is
   /// provided, inserts before that basic block, otherwise inserts at the end.
   ///
   /// \pre \a getParent() is \c nullptr.
   void insertInto(Function *Parent, BasicBlock *InsertBefore = nullptr);
 
   /// Return the predecessor of this block if it has a single predecessor
   /// block. Otherwise return a null pointer.
   const BasicBlock *getSinglePredecessor() const;
   BasicBlock *getSinglePredecessor() {
     return const_cast<BasicBlock *>(
                  static_cast<const BasicBlock *>(this)->getSinglePredecessor());
   }
 
   /// Return the predecessor of this block if it has a unique predecessor
   /// block. Otherwise return a null pointer.
   ///
   /// Note that unique predecessor doesn't mean single edge, there can be
   /// multiple edges from the unique predecessor to this block (for example a
   /// switch statement with multiple cases having the same destination).
   const BasicBlock *getUniquePredecessor() const;
   BasicBlock *getUniquePredecessor() {
     return const_cast<BasicBlock *>(
                  static_cast<const BasicBlock *>(this)->getUniquePredecessor());
   }
 
   /// Return true if this block has exactly N predecessors.
   bool hasNPredecessors(unsigned N) const;
 
   /// Return true if this block has N predecessors or more.
   bool hasNPredecessorsOrMore(unsigned N) const;
 
   /// Return the successor of this block if it has a single successor.
   /// Otherwise return a null pointer.
   ///
   /// This method is analogous to getSinglePredecessor above.
   const BasicBlock *getSingleSuccessor() const;
   BasicBlock *getSingleSuccessor() {
     return const_cast<BasicBlock *>(
                    static_cast<const BasicBlock *>(this)->getSingleSuccessor());
   }
 
   /// Return the successor of this block if it has a unique successor.
   /// Otherwise return a null pointer.
   ///
   /// This method is analogous to getUniquePredecessor above.
   const BasicBlock *getUniqueSuccessor() const;
   BasicBlock *getUniqueSuccessor() {
     return const_cast<BasicBlock *>(
                    static_cast<const BasicBlock *>(this)->getUniqueSuccessor());
   }
 
   /// Print the basic block to an output stream with an optional
   /// AssemblyAnnotationWriter.
   void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr,
              bool ShouldPreserveUseListOrder = false,
              bool IsForDebug = false) const;
 
   //===--------------------------------------------------------------------===//
   /// Instruction iterator methods
   ///
   inline iterator begin() {
     iterator It = InstList.begin();
     // Set the head-inclusive bit to indicate that this iterator includes
     // any debug-info at the start of the block. This is a no-op unless the
     // appropriate CMake flag is set.
     It.setHeadBit(true);
     return It;
   }
   inline const_iterator begin() const {
     const_iterator It = InstList.begin();
     It.setHeadBit(true);
     return It;
   }
   inline iterator                end  ()       { return InstList.end();   }
   inline const_iterator          end  () const { return InstList.end();   }
 
   inline reverse_iterator        rbegin()       { return InstList.rbegin(); }
   inline const_reverse_iterator  rbegin() const { return InstList.rbegin(); }
   inline reverse_iterator        rend  ()       { return InstList.rend();   }
   inline const_reverse_iterator  rend  () const { return InstList.rend();   }
 
   inline size_t                   size() const { return InstList.size();  }
   inline bool                    empty() const { return InstList.empty(); }
   inline const Instruction      &front() const { return InstList.front(); }
   inline       Instruction      &front()       { return InstList.front(); }
   inline const Instruction       &back() const { return InstList.back();  }
   inline       Instruction       &back()       { return InstList.back();  }
 
   /// Iterator to walk just the phi nodes in the basic block.
   template <typename PHINodeT = PHINode, typename BBIteratorT = iterator>
   class phi_iterator_impl
       : public iterator_facade_base<phi_iterator_impl<PHINodeT, BBIteratorT>,
                                     std::forward_iterator_tag, PHINodeT> {
     friend BasicBlock;
 
     PHINodeT *PN;
 
     phi_iterator_impl(PHINodeT *PN) : PN(PN) {}
 
   public:
     // Allow default construction to build variables, but this doesn't build
     // a useful iterator.
     phi_iterator_impl() = default;
 
     // Allow conversion between instantiations where valid.
     template <typename PHINodeU, typename BBIteratorU,
               typename = std::enable_if_t<
                   std::is_convertible<PHINodeU *, PHINodeT *>::value>>
     phi_iterator_impl(const phi_iterator_impl<PHINodeU, BBIteratorU> &Arg)
         : PN(Arg.PN) {}
 
     bool operator==(const phi_iterator_impl &Arg) const { return PN == Arg.PN; }
 
     PHINodeT &operator*() const { return *PN; }
 
     using phi_iterator_impl::iterator_facade_base::operator++;
     phi_iterator_impl &operator++() {
       assert(PN && "Cannot increment the end iterator!");
       PN = dyn_cast<PHINodeT>(std::next(BBIteratorT(PN)));
       return *this;
     }
   };
   using phi_iterator = phi_iterator_impl<>;
   using const_phi_iterator =
       phi_iterator_impl<const PHINode, BasicBlock::const_iterator>;
 
   /// Returns a range that iterates over the phis in the basic block.
   ///
   /// Note that this cannot be used with basic blocks that have no terminator.
   iterator_range<const_phi_iterator> phis() const {
     return const_cast<BasicBlock *>(this)->phis();
   }
   iterator_range<phi_iterator> phis();
 
 private:
   /// Return the underlying instruction list container.
   /// This is deliberately private because we have implemented an adequate set
   /// of functions to modify the list, including BasicBlock::splice(),
   /// BasicBlock::erase(), Instruction::insertInto() etc.
   const InstListType &getInstList() const { return InstList; }
   InstListType &getInstList() { return InstList; }
 
   /// Returns a pointer to a member of the instruction list.
   /// This is private on purpose, just like `getInstList()`.
   static InstListType BasicBlock::*getSublistAccess(Instruction *) {
     return &BasicBlock::InstList;
   }
 
   /// Dedicated function for splicing debug-info: when we have an empty
   /// splice (i.e. zero instructions), the caller may still intend any
   /// debug-info in between the two "positions" to be spliced.
   void spliceDebugInfoEmptyBlock(BasicBlock::iterator ToIt, BasicBlock *FromBB,
                                  BasicBlock::iterator FromBeginIt,
                                  BasicBlock::iterator FromEndIt);
 
   /// Perform any debug-info specific maintenence for the given splice
   /// activity. In the DbgRecord debug-info representation, debug-info is not
   /// in instructions, and so it does not automatically move from one block
   /// to another.
   void spliceDebugInfo(BasicBlock::iterator ToIt, BasicBlock *FromBB,
                        BasicBlock::iterator FromBeginIt,
                        BasicBlock::iterator FromEndIt);
   void spliceDebugInfoImpl(BasicBlock::iterator ToIt, BasicBlock *FromBB,
                            BasicBlock::iterator FromBeginIt,
                            BasicBlock::iterator FromEndIt);
 
 public:
   /// Returns a pointer to the symbol table if one exists.
   ValueSymbolTable *getValueSymbolTable();
 
   /// Methods for support type inquiry through isa, cast, and dyn_cast.
   static bool classof(const Value *V) {
     return V->getValueID() == Value::BasicBlockVal;
   }
 
   /// Cause all subinstructions to "let go" of all the references that said
   /// subinstructions are maintaining.
   ///
   /// This allows one to 'delete' a whole class at a time, even though there may
   /// be circular references... first all references are dropped, and all use
   /// counts go to zero.  Then everything is delete'd for real.  Note that no
   /// operations are valid on an object that has "dropped all references",
   /// except operator delete.
   void dropAllReferences();
 
   /// Update PHI nodes in this BasicBlock before removal of predecessor \p Pred.
   /// Note that this function does not actually remove the predecessor.
   ///
   /// If \p KeepOneInputPHIs is true then don't remove PHIs that are left with
   /// zero or one incoming values, and don't simplify PHIs with all incoming
   /// values the same.
   void removePredecessor(BasicBlock *Pred, bool KeepOneInputPHIs = false);
 
   bool canSplitPredecessors() const;
 
   /// Split the basic block into two basic blocks at the specified instruction.
   ///
   /// If \p Before is true, splitBasicBlockBefore handles the
   /// block splitting. Otherwise, execution proceeds as described below.
   ///
   /// Note that all instructions BEFORE the specified iterator
   /// stay as part of the original basic block, an unconditional branch is added
   /// to the original BB, and the rest of the instructions in the BB are moved
   /// to the new BB, including the old terminator.  The newly formed basic block
   /// is returned. This function invalidates the specified iterator.
   ///
   /// Note that this only works on well formed basic blocks (must have a
   /// terminator), and \p 'I' must not be the end of instruction list (which
   /// would cause a degenerate basic block to be formed, having a terminator
   /// inside of the basic block).
   ///
   /// Also note that this doesn't preserve any passes. To split blocks while
   /// keeping loop information consistent, use the SplitBlock utility function.
   BasicBlock *splitBasicBlock(iterator I, const Twine &BBName = "",
                               bool Before = false);
   BasicBlock *splitBasicBlock(Instruction *I, const Twine &BBName = "",
                               bool Before = false) {
     return splitBasicBlock(I->getIterator(), BBName, Before);
   }
 
   /// Split the basic block into two basic blocks at the specified instruction
   /// and insert the new basic blocks as the predecessor of the current block.
   ///
   /// This function ensures all instructions AFTER and including the specified
   /// iterator \p I are part of the original basic block. All Instructions
   /// BEFORE the iterator \p I are moved to the new BB and an unconditional
   /// branch is added to the new BB. The new basic block is returned.
   ///
   /// Note that this only works on well formed basic blocks (must have a
   /// terminator), and \p 'I' must not be the end of instruction list (which
   /// would cause a degenerate basic block to be formed, having a terminator
   /// inside of the basic block).  \p 'I' cannot be a iterator for a PHINode
   /// with multiple incoming blocks.
   ///
   /// Also note that this doesn't preserve any passes. To split blocks while
   /// keeping loop information consistent, use the SplitBlockBefore utility
   /// function.
   BasicBlock *splitBasicBlockBefore(iterator I, const Twine &BBName = "");
   BasicBlock *splitBasicBlockBefore(Instruction *I, const Twine &BBName = "") {
     return splitBasicBlockBefore(I->getIterator(), BBName);
   }
 
   /// Transfer all instructions from \p FromBB to this basic block at \p ToIt.
   void splice(BasicBlock::iterator ToIt, BasicBlock *FromBB) {
     splice(ToIt, FromBB, FromBB->begin(), FromBB->end());
   }
 
   /// Transfer one instruction from \p FromBB at \p FromIt to this basic block
   /// at \p ToIt.
   void splice(BasicBlock::iterator ToIt, BasicBlock *FromBB,
               BasicBlock::iterator FromIt) {
     auto FromItNext = std::next(FromIt);
     // Single-element splice is a noop if destination == source.
     if (ToIt == FromIt || ToIt == FromItNext)
       return;
     splice(ToIt, FromBB, FromIt, FromItNext);
   }
 
   /// Transfer a range of instructions that belong to \p FromBB from \p
   /// FromBeginIt to \p FromEndIt, to this basic block at \p ToIt.
   void splice(BasicBlock::iterator ToIt, BasicBlock *FromBB,
               BasicBlock::iterator FromBeginIt,
               BasicBlock::iterator FromEndIt);
 
   /// Erases a range of instructions from \p FromIt to (not including) \p ToIt.
   /// \Returns \p ToIt.
   BasicBlock::iterator erase(BasicBlock::iterator FromIt, BasicBlock::iterator ToIt);
 
   /// Returns true if there are any uses of this basic block other than
   /// direct branches, switches, etc. to it.
   bool hasAddressTaken() const {
     return getBasicBlockBits().BlockAddressRefCount != 0;
   }
 
   /// Update all phi nodes in this basic block to refer to basic block \p New
   /// instead of basic block \p Old.
   void replacePhiUsesWith(BasicBlock *Old, BasicBlock *New);
 
   /// Update all phi nodes in this basic block's successors to refer to basic
   /// block \p New instead of basic block \p Old.
   void replaceSuccessorsPhiUsesWith(BasicBlock *Old, BasicBlock *New);
 
   /// Update all phi nodes in this basic block's successors to refer to basic
   /// block \p New instead of to it.
   void replaceSuccessorsPhiUsesWith(BasicBlock *New);
 
   /// Return true if this basic block is an exception handling block.
   bool isEHPad() const { return getFirstNonPHIIt()->isEHPad(); }
 
   /// Return true if this basic block is a landing pad.
   ///
   /// Being a ``landing pad'' means that the basic block is the destination of
   /// the 'unwind' edge of an invoke instruction.
   bool isLandingPad() const;
 
   /// Return the landingpad instruction associated with the landing pad.
   const LandingPadInst *getLandingPadInst() const;
   LandingPadInst *getLandingPadInst() {
     return const_cast<LandingPadInst *>(
                     static_cast<const BasicBlock *>(this)->getLandingPadInst());
   }
 
   /// Return true if it is legal to hoist instructions into this block.
   bool isLegalToHoistInto() const;
 
   /// Return true if this is the entry block of the containing function.
   /// This method can only be used on blocks that have a parent function.
   bool isEntryBlock() const;
 
   std::optional<uint64_t> getIrrLoopHeaderWeight() const;
 
   /// Returns true if the Order field of child Instructions is valid.
   bool isInstrOrderValid() const {
     return getBasicBlockBits().InstrOrderValid;
   }
 
   /// Mark instruction ordering invalid. Done on every instruction insert.
   void invalidateOrders() {
     validateInstrOrdering();
     BasicBlockBits Bits = getBasicBlockBits();
     Bits.InstrOrderValid = false;
     setBasicBlockBits(Bits);
   }
 
   /// Renumber instructions and mark the ordering as valid.
   void renumberInstructions();
 
   /// Asserts that instruction order numbers are marked invalid, or that they
   /// are in ascending order. This is constant time if the ordering is invalid,
   /// and linear in the number of instructions if the ordering is valid. Callers
   /// should be careful not to call this in ways that make common operations
   /// O(n^2). For example, it takes O(n) time to assign order numbers to
   /// instructions, so the order should be validated no more than once after
   /// each ordering to ensure that transforms have the same algorithmic
   /// complexity when asserts are enabled as when they are disabled.
   void validateInstrOrdering() const;
 
 private:
 #if defined(_AIX) && (!defined(__GNUC__) || defined(__clang__))
 // Except for GCC; by default, AIX compilers store bit-fields in 4-byte words
 // and give the `pack` pragma push semantics.
 #define BEGIN_TWO_BYTE_PACK() _Pragma("pack(2)")
 #define END_TWO_BYTE_PACK() _Pragma("pack(pop)")
 #else
 #define BEGIN_TWO_BYTE_PACK()
 #define END_TWO_BYTE_PACK()
 #endif
 
   BEGIN_TWO_BYTE_PACK()
   /// Bitfield to help interpret the bits in Value::SubclassData.
   struct BasicBlockBits {
     unsigned short BlockAddressRefCount : 15;
     unsigned short InstrOrderValid : 1;
   };
   END_TWO_BYTE_PACK()
 
 #undef BEGIN_TWO_BYTE_PACK
 #undef END_TWO_BYTE_PACK
 
   /// Safely reinterpret the subclass data bits to a more useful form.
   BasicBlockBits getBasicBlockBits() const {
     static_assert(sizeof(BasicBlockBits) == sizeof(unsigned short),
                   "too many bits for Value::SubclassData");
     unsigned short ValueData = getSubclassDataFromValue();
     BasicBlockBits AsBits;
     memcpy(&AsBits, &ValueData, sizeof(AsBits));
     return AsBits;
   }
 
   /// Reinterpret our subclass bits and store them back into Value.
   void setBasicBlockBits(BasicBlockBits AsBits) {
     unsigned short D;
     memcpy(&D, &AsBits, sizeof(D));
     Value::setValueSubclassData(D);
   }
 
   /// Increment the internal refcount of the number of BlockAddresses
   /// referencing this BasicBlock by \p Amt.
   ///
   /// This is almost always 0, sometimes one possibly, but almost never 2, and
   /// inconceivably 3 or more.
   void AdjustBlockAddressRefCount(int Amt) {
     BasicBlockBits Bits = getBasicBlockBits();
     Bits.BlockAddressRefCount += Amt;
     setBasicBlockBits(Bits);
     assert(Bits.BlockAddressRefCount < 255 && "Refcount wrap-around");
   }
 
   /// Shadow Value::setValueSubclassData with a private forwarding method so
   /// that any future subclasses cannot accidentally use it.
   void setValueSubclassData(unsigned short D) {
     Value::setValueSubclassData(D);
   }
 };
 
 // Create wrappers for C Binding types (see CBindingWrapping.h).
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(BasicBlock, LLVMBasicBlockRef)
 
 /// Advance \p It while it points to a debug instruction and return the result.
 /// This assumes that \p It is not at the end of a block.
 BasicBlock::iterator skipDebugIntrinsics(BasicBlock::iterator It);
 
 #ifdef NDEBUG
 /// In release builds, this is a no-op. For !NDEBUG builds, the checks are
 /// implemented in the .cpp file to avoid circular header deps.
 inline void BasicBlock::validateInstrOrdering() const {}
 #endif
 
 // Specialize DenseMapInfo for iterators, so that ththey can be installed into
 // maps and sets. The iterator is made up of its node pointer, and the
 // debug-info "head" bit.
 template <> struct DenseMapInfo<BasicBlock::iterator> {
   static inline BasicBlock::iterator getEmptyKey() {
     return BasicBlock::iterator(nullptr);
   }
 
   static inline BasicBlock::iterator getTombstoneKey() {
     BasicBlock::iterator It(nullptr);
     It.setHeadBit(true);
     return It;
   }
 
   static unsigned getHashValue(const BasicBlock::iterator &It) {
     return DenseMapInfo<void *>::getHashValue(
                reinterpret_cast<void *>(It.getNodePtr())) ^
            (unsigned)It.getHeadBit();
   }
 
   static bool isEqual(const BasicBlock::iterator &LHS,
                       const BasicBlock::iterator &RHS) {
     return LHS == RHS && LHS.getHeadBit() == RHS.getHeadBit();
   }
 };
 
 } // end namespace llvm
 
 #endif // LLVM_IR_BASICBLOCK_H

This page was automatically generated by the 2.3.7 LXR engine. The LXR team