| //===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the declaration of the BasicBlock class. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_IR_BASICBLOCK_H |
| #define LLVM_IR_BASICBLOCK_H |
| |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/ADT/ilist.h" |
| #include "llvm/IR/Instruction.h" |
| #include "llvm/IR/SymbolTableListTraits.h" |
| #include "llvm/Support/CBindingWrapping.h" |
| #include "llvm/Support/DataTypes.h" |
| |
| namespace llvm { |
| |
| class LandingPadInst; |
| class TerminatorInst; |
| class LLVMContext; |
| class BlockAddress; |
| |
| template<> struct ilist_traits<Instruction> |
| : public SymbolTableListTraits<Instruction, BasicBlock> { |
| |
| /// \brief Return a node that marks the end of a list. |
| /// |
| /// The sentinel is relative to this instance, so we use a non-static |
| /// method. |
| Instruction *createSentinel() const { |
| // Since i(p)lists always publicly derive from their corresponding traits, |
| // placing a data member in this class will augment the i(p)list. But since |
| // the NodeTy is expected to be publicly derive from ilist_node<NodeTy>, |
| // there is a legal viable downcast from it to NodeTy. We use this trick to |
| // superimpose an i(p)list with a "ghostly" NodeTy, which becomes the |
| // sentinel. Dereferencing the sentinel is forbidden (save the |
| // ilist_node<NodeTy>), so no one will ever notice the superposition. |
| return static_cast<Instruction*>(&Sentinel); |
| } |
| static void destroySentinel(Instruction*) {} |
| |
| Instruction *provideInitialHead() const { return createSentinel(); } |
| Instruction *ensureHead(Instruction*) const { return createSentinel(); } |
| static void noteHead(Instruction*, Instruction*) {} |
| private: |
| mutable ilist_half_node<Instruction> Sentinel; |
| }; |
| |
| /// \brief 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 TerminatorInst instruction. |
| /// TerminatorInst's 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 : public Value, // Basic blocks are data objects also |
| public ilist_node<BasicBlock> { |
| friend class BlockAddress; |
| public: |
| typedef iplist<Instruction> InstListType; |
| private: |
| InstListType InstList; |
| Function *Parent; |
| |
| void setParent(Function *parent); |
| friend class SymbolTableListTraits<BasicBlock, Function>; |
| |
| BasicBlock(const BasicBlock &) LLVM_DELETED_FUNCTION; |
| void operator=(const BasicBlock &) LLVM_DELETED_FUNCTION; |
| |
| /// \brief 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: |
| /// \brief Get the context in which this basic block lives. |
| LLVMContext &getContext() const; |
| |
| /// Instruction iterators... |
| typedef InstListType::iterator iterator; |
| typedef InstListType::const_iterator const_iterator; |
| typedef InstListType::reverse_iterator reverse_iterator; |
| typedef InstListType::const_reverse_iterator const_reverse_iterator; |
| |
| /// \brief 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); |
| } |
| ~BasicBlock(); |
| |
| /// \brief Return the enclosing method, or null if none. |
| const Function *getParent() const { return Parent; } |
| Function *getParent() { return Parent; } |
| |
| const DataLayout *getDataLayout() const; |
| |
| /// \brief Returns the terminator instruction if the block is well formed or |
| /// null if the block is not well formed. |
| TerminatorInst *getTerminator(); |
| const TerminatorInst *getTerminator() const; |
| |
| /// \brief 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. |
| Instruction* getFirstNonPHI(); |
| const Instruction* getFirstNonPHI() const { |
| return const_cast<BasicBlock*>(this)->getFirstNonPHI(); |
| } |
| |
| /// \brief Returns a pointer to the first instruction in this block that is not |
| /// a PHINode or a debug intrinsic. |
| Instruction* getFirstNonPHIOrDbg(); |
| const Instruction* getFirstNonPHIOrDbg() const { |
| return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbg(); |
| } |
| |
| /// \brief Returns a pointer to the first instruction in this block that is not |
| /// a PHINode, a debug intrinsic, or a lifetime intrinsic. |
| Instruction* getFirstNonPHIOrDbgOrLifetime(); |
| const Instruction* getFirstNonPHIOrDbgOrLifetime() const { |
| return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbgOrLifetime(); |
| } |
| |
| /// \brief 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. |
| iterator getFirstInsertionPt(); |
| const_iterator getFirstInsertionPt() const { |
| return const_cast<BasicBlock*>(this)->getFirstInsertionPt(); |
| } |
| |
| /// \brief Unlink 'this' from the containing function, but do not delete it. |
| void removeFromParent(); |
| |
| /// \brief Unlink 'this' from the containing function and delete it. |
| void eraseFromParent(); |
| |
| /// \brief Unlink this basic block from its current function and insert it |
| /// into the function that \p MovePos lives in, right before \p MovePos. |
| void moveBefore(BasicBlock *MovePos); |
| |
| /// \brief 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); |
| |
| |
| /// \brief Return the predecessor of this block if it has a single predecessor |
| /// block. Otherwise return a null pointer. |
| BasicBlock *getSinglePredecessor(); |
| const BasicBlock *getSinglePredecessor() const { |
| return const_cast<BasicBlock*>(this)->getSinglePredecessor(); |
| } |
| |
| /// \brief 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). |
| BasicBlock *getUniquePredecessor(); |
| const BasicBlock *getUniquePredecessor() const { |
| return const_cast<BasicBlock*>(this)->getUniquePredecessor(); |
| } |
| |
| //===--------------------------------------------------------------------===// |
| /// Instruction iterator methods |
| /// |
| inline iterator begin() { return InstList.begin(); } |
| inline const_iterator begin() const { return InstList.begin(); } |
| 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(); } |
| |
| /// \brief Return the underlying instruction list container. |
| /// |
| /// Currently you need to access the underlying instruction list container |
| /// directly if you want to modify it. |
| const InstListType &getInstList() const { return InstList; } |
| InstListType &getInstList() { return InstList; } |
| |
| /// \brief Returns a pointer to a member of the instruction list. |
| static iplist<Instruction> BasicBlock::*getSublistAccess(Instruction*) { |
| return &BasicBlock::InstList; |
| } |
| |
| /// \brief Returns a pointer to the symbol table if one exists. |
| ValueSymbolTable *getValueSymbolTable(); |
| |
| /// \brief Methods for support type inquiry through isa, cast, and dyn_cast. |
| static inline bool classof(const Value *V) { |
| return V->getValueID() == Value::BasicBlockVal; |
| } |
| |
| /// \brief 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(); |
| |
| /// \brief Notify the BasicBlock that the predecessor \p Pred is no longer |
| /// able to reach it. |
| /// |
| /// This is actually not used to update the Predecessor list, but is actually |
| /// used to update the PHI nodes that reside in the block. Note that this |
| /// should be called while the predecessor still refers to this block. |
| void removePredecessor(BasicBlock *Pred, bool DontDeleteUselessPHIs = false); |
| |
| /// \brief Split the basic block into two basic blocks at the specified |
| /// instruction. |
| /// |
| /// 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 BasicBlock is returned. |
| /// This function invalidates the specified iterator. |
| /// |
| /// Note that this only works on well formed basic blocks (must have a |
| /// terminator), and '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 = ""); |
| |
| /// \brief Returns true if there are any uses of this basic block other than |
| /// direct branches, switches, etc. to it. |
| bool hasAddressTaken() const { return getSubclassDataFromValue() != 0; } |
| |
| /// \brief 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); |
| |
| /// \brief 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; |
| |
| /// \brief Return the landingpad instruction associated with the landing pad. |
| LandingPadInst *getLandingPadInst(); |
| const LandingPadInst *getLandingPadInst() const; |
| |
| private: |
| /// \brief 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) { |
| setValueSubclassData(getSubclassDataFromValue()+Amt); |
| assert((int)(signed char)getSubclassDataFromValue() >= 0 && |
| "Refcount wrap-around"); |
| } |
| /// \brief 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) |
| |
| } // End llvm namespace |
| |
| #endif |