LLVM API Documentation
00001 //===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // 00011 // This file contains the declaration of the BasicBlock class, which represents 00012 // a single basic block in the VM. 00013 // 00014 // Note that basic blocks themselves are Value's, because they are referenced 00015 // by instructions like branches and can go in switch tables and stuff... 00016 // 00017 ///===---------------------------------------------------------------------===// 00018 // 00019 // Note that well formed basic blocks are formed of a list of instructions 00020 // followed by a single TerminatorInst instruction. TerminatorInst's may not 00021 // occur in the middle of basic blocks, and must terminate the blocks. 00022 // 00023 // This code allows malformed basic blocks to occur, because it may be useful 00024 // in the intermediate stage modification to a program. 00025 // 00026 //===----------------------------------------------------------------------===// 00027 00028 #ifndef LLVM_BASICBLOCK_H 00029 #define LLVM_BASICBLOCK_H 00030 00031 #include "llvm/Instruction.h" 00032 #include "llvm/SymbolTableListTraits.h" 00033 #include "llvm/ADT/ilist" 00034 00035 namespace llvm { 00036 00037 class TerminatorInst; 00038 template <class Term, class BB> class SuccIterator; // Successor Iterator 00039 template <class Ptr, class USE_iterator> class PredIterator; 00040 00041 template<> struct ilist_traits<Instruction> 00042 : public SymbolTableListTraits<Instruction, BasicBlock, Function> { 00043 // createNode is used to create a node that marks the end of the list... 00044 static Instruction *createNode(); 00045 static iplist<Instruction> &getList(BasicBlock *BB); 00046 }; 00047 00048 class BasicBlock : public Value { // Basic blocks are data objects also 00049 public: 00050 typedef iplist<Instruction> InstListType; 00051 private : 00052 InstListType InstList; 00053 BasicBlock *Prev, *Next; // Next and Prev links for our intrusive linked list 00054 00055 void setParent(Function *parent); 00056 void setNext(BasicBlock *N) { Next = N; } 00057 void setPrev(BasicBlock *N) { Prev = N; } 00058 friend class SymbolTableListTraits<BasicBlock, Function, Function>; 00059 00060 BasicBlock(const BasicBlock &); // Do not implement 00061 void operator=(const BasicBlock &); // Do not implement 00062 00063 public: 00064 /// Instruction iterators... 00065 typedef InstListType::iterator iterator; 00066 typedef InstListType::const_iterator const_iterator; 00067 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 00068 typedef std::reverse_iterator<iterator> reverse_iterator; 00069 00070 /// BasicBlock ctor - If the function parameter is specified, the basic block 00071 /// is automatically inserted at either the end of the function (if 00072 /// InsertBefore is null), or before the specified basic block. 00073 /// 00074 BasicBlock(const std::string &Name = "", Function *Parent = 0, 00075 BasicBlock *InsertBefore = 0); 00076 ~BasicBlock(); 00077 00078 // Specialize setName to take care of symbol table majik 00079 virtual void setName(const std::string &name, SymbolTable *ST = 0); 00080 00081 /// getParent - Return the enclosing method, or null if none 00082 /// 00083 const Function *getParent() const { return InstList.getParent(); } 00084 Function *getParent() { return InstList.getParent(); } 00085 00086 // getNext/Prev - Return the next or previous basic block in the list. 00087 BasicBlock *getNext() { return Next; } 00088 const BasicBlock *getNext() const { return Next; } 00089 BasicBlock *getPrev() { return Prev; } 00090 const BasicBlock *getPrev() const { return Prev; } 00091 00092 /// getTerminator() - If this is a well formed basic block, then this returns 00093 /// a pointer to the terminator instruction. If it is not, then you get a 00094 /// null pointer back. 00095 /// 00096 TerminatorInst *getTerminator(); 00097 const TerminatorInst *const getTerminator() const; 00098 00099 /// removeFromParent - This method unlinks 'this' from the containing 00100 /// function, but does not delete it. 00101 /// 00102 void removeFromParent(); 00103 00104 /// eraseFromParent - This method unlinks 'this' from the containing function 00105 /// and deletes it. 00106 /// 00107 void eraseFromParent(); 00108 00109 00110 00111 //===--------------------------------------------------------------------===// 00112 /// Instruction iterator methods 00113 /// 00114 inline iterator begin() { return InstList.begin(); } 00115 inline const_iterator begin() const { return InstList.begin(); } 00116 inline iterator end () { return InstList.end(); } 00117 inline const_iterator end () const { return InstList.end(); } 00118 00119 inline reverse_iterator rbegin() { return InstList.rbegin(); } 00120 inline const_reverse_iterator rbegin() const { return InstList.rbegin(); } 00121 inline reverse_iterator rend () { return InstList.rend(); } 00122 inline const_reverse_iterator rend () const { return InstList.rend(); } 00123 00124 inline size_t size() const { return InstList.size(); } 00125 inline bool empty() const { return InstList.empty(); } 00126 inline const Instruction &front() const { return InstList.front(); } 00127 inline Instruction &front() { return InstList.front(); } 00128 inline const Instruction &back() const { return InstList.back(); } 00129 inline Instruction &back() { return InstList.back(); } 00130 00131 /// getInstList() - Return the underlying instruction list container. You 00132 /// need to access it directly if you want to modify it currently. 00133 /// 00134 const InstListType &getInstList() const { return InstList; } 00135 InstListType &getInstList() { return InstList; } 00136 00137 virtual void print(std::ostream &OS) const { print(OS, 0); } 00138 void print(std::ostream &OS, AssemblyAnnotationWriter *AAW) const; 00139 00140 /// Methods for support type inquiry through isa, cast, and dyn_cast: 00141 static inline bool classof(const BasicBlock *BB) { return true; } 00142 static inline bool classof(const Value *V) { 00143 return V->getValueType() == Value::BasicBlockVal; 00144 } 00145 00146 /// dropAllReferences() - This function causes all the subinstructions to "let 00147 /// go" of all references that they are maintaining. This allows one to 00148 /// 'delete' a whole class at a time, even though there may be circular 00149 /// references... first all references are dropped, and all use counts go to 00150 /// zero. Then everything is delete'd for real. Note that no operations are 00151 /// valid on an object that has "dropped all references", except operator 00152 /// delete. 00153 /// 00154 void dropAllReferences(); 00155 00156 /// removePredecessor - This method is used to notify a BasicBlock that the 00157 /// specified Predecessor of the block is no longer able to reach it. This is 00158 /// actually not used to update the Predecessor list, but is actually used to 00159 /// update the PHI nodes that reside in the block. Note that this should be 00160 /// called while the predecessor still refers to this block. 00161 /// 00162 void removePredecessor(BasicBlock *Pred); 00163 00164 /// splitBasicBlock - This splits a basic block into two at the specified 00165 /// instruction. Note that all instructions BEFORE the specified iterator 00166 /// stay as part of the original basic block, an unconditional branch is added 00167 /// to the new BB, and the rest of the instructions in the BB are moved to the 00168 /// new BB, including the old terminator. The newly formed BasicBlock is 00169 /// returned. This function invalidates the specified iterator. 00170 /// 00171 /// Note that this only works on well formed basic blocks (must have a 00172 /// terminator), and 'I' must not be the end of instruction list (which would 00173 /// cause a degenerate basic block to be formed, having a terminator inside of 00174 /// the basic block). 00175 /// 00176 BasicBlock *splitBasicBlock(iterator I, const std::string &BBName = ""); 00177 }; 00178 00179 } // End llvm namespace 00180 00181 #endif