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Diffstat (limited to 'include/llvm/IR/BasicBlock.h')
| -rw-r--r-- | include/llvm/IR/BasicBlock.h | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/include/llvm/IR/BasicBlock.h b/include/llvm/IR/BasicBlock.h new file mode 100644 index 0000000..ea5695a --- /dev/null +++ b/include/llvm/IR/BasicBlock.h @@ -0,0 +1,303 @@ +//===-- 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/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 = 0, BasicBlock *InsertBefore = 0); +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 = 0,BasicBlock *InsertBefore = 0) { + 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; } + + /// \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 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 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); + } +}; + +} // End llvm namespace + +#endif |
