1 //===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 // This file contains the declaration of the BasicBlock class, which represents
12 // a single basic block in the VM.
14 // Note that basic blocks themselves are Value's, because they are referenced
15 // by instructions like branches and can go in switch tables and stuff...
17 ///===---------------------------------------------------------------------===//
19 // Note that well formed basic blocks are formed of a list of instructions
20 // followed by a single TerminatorInst instruction. TerminatorInst's may not
21 // occur in the middle of basic blocks, and must terminate the blocks.
23 // This code allows malformed basic blocks to occur, because it may be useful
24 // in the intermediate stage modification to a program.
26 //===----------------------------------------------------------------------===//
28 #ifndef LLVM_BASICBLOCK_H
29 #define LLVM_BASICBLOCK_H
31 #include "llvm/Instruction.h"
32 #include "llvm/SymbolTableListTraits.h"
33 #include "Support/ilist"
38 template <class _Term, class _BB> class SuccIterator; // Successor Iterator
39 template <class _Ptr, class _USE_iterator> class PredIterator;
41 template<> struct ilist_traits<Instruction>
42 : public SymbolTableListTraits<Instruction, BasicBlock, Function> {
43 // createNode is used to create a node that marks the end of the list...
44 static Instruction *createNode();
45 static iplist<Instruction> &getList(BasicBlock *BB);
48 struct BasicBlock : public Value { // Basic blocks are data objects also
49 typedef iplist<Instruction> InstListType;
51 InstListType InstList;
52 BasicBlock *Prev, *Next; // Next and Prev links for our intrusive linked list
54 void setParent(Function *parent);
55 void setNext(BasicBlock *N) { Next = N; }
56 void setPrev(BasicBlock *N) { Prev = N; }
57 friend class SymbolTableListTraits<BasicBlock, Function, Function>;
59 BasicBlock(const BasicBlock &); // Do not implement
60 void operator=(const BasicBlock &); // Do not implement
63 /// Instruction iterators...
64 typedef InstListType::iterator iterator;
65 typedef InstListType::const_iterator const_iterator;
66 typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
67 typedef std::reverse_iterator<iterator> reverse_iterator;
69 /// BasicBlock ctor - If the function parameter is specified, the basic block
70 /// is automatically inserted at either the end of the function (if
71 /// InsertBefore is null), or before the specified basic block.
73 /// BasicBlock ctor - If the InsertBefore parameter is specified, the basic
74 /// block is automatically inserted right before the specified block.
76 BasicBlock(const std::string &Name = "", Function *Parent = 0,
77 BasicBlock *InsertBefore = 0);
80 // Specialize setName to take care of symbol table majik
81 virtual void setName(const std::string &name, SymbolTable *ST = 0);
83 /// getParent - Return the enclosing method, or null if none
85 const Function *getParent() const { return InstList.getParent(); }
86 Function *getParent() { return InstList.getParent(); }
88 // getNext/Prev - Return the next or previous basic block in the list.
89 BasicBlock *getNext() { return Next; }
90 const BasicBlock *getNext() const { return Next; }
91 BasicBlock *getPrev() { return Prev; }
92 const BasicBlock *getPrev() const { return Prev; }
94 /// getTerminator() - If this is a well formed basic block, then this returns
95 /// a pointer to the terminator instruction. If it is not, then you get a
96 /// null pointer back.
98 TerminatorInst *getTerminator();
99 const TerminatorInst *const getTerminator() const;
101 //===--------------------------------------------------------------------===//
102 /// Instruction iterator methods
104 inline iterator begin() { return InstList.begin(); }
105 inline const_iterator begin() const { return InstList.begin(); }
106 inline iterator end () { return InstList.end(); }
107 inline const_iterator end () const { return InstList.end(); }
109 inline reverse_iterator rbegin() { return InstList.rbegin(); }
110 inline const_reverse_iterator rbegin() const { return InstList.rbegin(); }
111 inline reverse_iterator rend () { return InstList.rend(); }
112 inline const_reverse_iterator rend () const { return InstList.rend(); }
114 inline unsigned size() const { return InstList.size(); }
115 inline bool empty() const { return InstList.empty(); }
116 inline const Instruction &front() const { return InstList.front(); }
117 inline Instruction &front() { return InstList.front(); }
118 inline const Instruction &back() const { return InstList.back(); }
119 inline Instruction &back() { return InstList.back(); }
121 /// getInstList() - Return the underlying instruction list container. You
122 /// need to access it directly if you want to modify it currently.
124 const InstListType &getInstList() const { return InstList; }
125 InstListType &getInstList() { return InstList; }
127 virtual void print(std::ostream &OS) const { print(OS, 0); }
128 void print(std::ostream &OS, AssemblyAnnotationWriter *AAW) const;
130 /// Methods for support type inquiry through isa, cast, and dyn_cast:
131 static inline bool classof(const BasicBlock *BB) { return true; }
132 static inline bool classof(const Value *V) {
133 return V->getValueType() == Value::BasicBlockVal;
136 /// dropAllReferences() - This function causes all the subinstructions to "let
137 /// go" of all references that they are maintaining. This allows one to
138 /// 'delete' a whole class at a time, even though there may be circular
139 /// references... first all references are dropped, and all use counts go to
140 /// zero. Then everything is delete'd for real. Note that no operations are
141 /// valid on an object that has "dropped all references", except operator
144 void dropAllReferences();
146 /// removePredecessor - This method is used to notify a BasicBlock that the
147 /// specified Predecessor of the block is no longer able to reach it. This is
148 /// actually not used to update the Predecessor list, but is actually used to
149 /// update the PHI nodes that reside in the block. Note that this should be
150 /// called while the predecessor still refers to this block.
152 void removePredecessor(BasicBlock *Pred);
154 /// splitBasicBlock - This splits a basic block into two at the specified
155 /// instruction. Note that all instructions BEFORE the specified iterator
156 /// stay as part of the original basic block, an unconditional branch is added
157 /// to the new BB, and the rest of the instructions in the BB are moved to the
158 /// new BB, including the old terminator. The newly formed BasicBlock is
159 /// returned. This function invalidates the specified iterator.
161 /// Note that this only works on well formed basic blocks (must have a
162 /// terminator), and 'I' must not be the end of instruction list (which would
163 /// cause a degenerate basic block to be formed, having a terminator inside of
164 /// the basic block).
166 BasicBlock *splitBasicBlock(iterator I, const std::string &BBName = "");
169 } // End llvm namespace