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222 lines
9.4 KiB
C++
222 lines
9.4 KiB
C++
//===-- llvm/BasicBlock.h - Represent a basic block in the VM ---*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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//
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// This file contains the declaration of the BasicBlock class.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_BASICBLOCK_H
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#define LLVM_BASICBLOCK_H
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#include "llvm/Instruction.h"
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#include "llvm/SymbolTableListTraits.h"
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#include "llvm/ADT/ilist"
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#include "llvm/Support/DataTypes.h"
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namespace llvm {
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class TerminatorInst;
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template <class Term, class BB> class SuccIterator; // Successor Iterator
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template <class Ptr, class USE_iterator> class PredIterator;
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template<> struct ilist_traits<Instruction>
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: public SymbolTableListTraits<Instruction, BasicBlock> {
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// createSentinel is used to create a node that marks the end of the list...
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static Instruction *createSentinel();
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static void destroySentinel(Instruction *I) { delete I; }
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static iplist<Instruction> &getList(BasicBlock *BB);
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static ValueSymbolTable *getSymTab(BasicBlock *ItemParent);
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static int getListOffset();
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};
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/// This represents a single basic block in LLVM. A basic block is simply a
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/// container of instructions that execute sequentially. Basic blocks are Values
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/// because they are referenced by instructions such as branches and switch
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/// tables. The type of a BasicBlock is "Type::LabelTy" because the basic block
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/// represents a label to which a branch can jump.
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///
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/// A well formed basic block is formed of a list of non-terminating
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/// instructions followed by a single TerminatorInst instruction.
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/// TerminatorInst's may not occur in the middle of basic blocks, and must
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/// terminate the blocks. The BasicBlock class allows malformed basic blocks to
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/// occur because it may be useful in the intermediate stage of constructing or
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/// modifying a program. However, the verifier will ensure that basic blocks
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/// are "well formed".
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/// @brief LLVM Basic Block Representation
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class BasicBlock : public Value { // Basic blocks are data objects also
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public:
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typedef iplist<Instruction> InstListType;
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private :
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InstListType InstList;
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BasicBlock *Prev, *Next; // Next and Prev links for our intrusive linked list
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Function *Parent;
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void setParent(Function *parent);
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void setNext(BasicBlock *N) { Next = N; }
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void setPrev(BasicBlock *N) { Prev = N; }
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friend class SymbolTableListTraits<BasicBlock, Function>;
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BasicBlock(const BasicBlock &); // Do not implement
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void operator=(const BasicBlock &); // Do not implement
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/// BasicBlock ctor - If the function parameter is specified, the basic block
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/// is automatically inserted at either the end of the function (if
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/// InsertBefore is null), or before the specified basic block.
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///
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explicit BasicBlock(const std::string &Name = "", Function *Parent = 0,
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BasicBlock *InsertBefore = 0);
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public:
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/// Instruction iterators...
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typedef InstListType::iterator iterator;
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typedef InstListType::const_iterator const_iterator;
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// allocate space for exactly zero operands
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static BasicBlock *Create(const std::string &Name = "", Function *Parent = 0,
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BasicBlock *InsertBefore = 0) {
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return new BasicBlock(Name, Parent, InsertBefore);
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}
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~BasicBlock();
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/// getParent - Return the enclosing method, or null if none
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///
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const Function *getParent() const { return Parent; }
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Function *getParent() { return Parent; }
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/// use_back - Specialize the methods defined in Value, as we know that an
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/// BasicBlock can only be used by Instructions (specifically PHI and terms).
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Instruction *use_back() { return cast<Instruction>(*use_begin());}
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const Instruction *use_back() const { return cast<Instruction>(*use_begin());}
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/// getTerminator() - If this is a well formed basic block, then this returns
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/// a pointer to the terminator instruction. If it is not, then you get a
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/// null pointer back.
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///
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TerminatorInst *getTerminator();
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const TerminatorInst *getTerminator() const;
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/// Returns a pointer to the first instructon in this block that is not a
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/// PHINode instruction. When adding instruction to the beginning of the
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/// basic block, they should be added before the returned value, not before
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/// the first instruction, which might be PHI.
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/// Returns 0 is there's no non-PHI instruction.
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Instruction* getFirstNonPHI();
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/// removeFromParent - This method unlinks 'this' from the containing
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/// function, but does not delete it.
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///
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void removeFromParent();
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/// eraseFromParent - This method unlinks 'this' from the containing function
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/// and deletes it.
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///
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void eraseFromParent();
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/// moveBefore - Unlink this basic block from its current function and
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/// insert it into the function that MovePos lives in, right before MovePos.
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void moveBefore(BasicBlock *MovePos);
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/// moveAfter - Unlink this basic block from its current function and
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/// insert it into the function that MovePos lives in, right after MovePos.
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void moveAfter(BasicBlock *MovePos);
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/// getSinglePredecessor - If this basic block has a single predecessor block,
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/// return the block, otherwise return a null pointer.
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BasicBlock *getSinglePredecessor();
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const BasicBlock *getSinglePredecessor() const {
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return const_cast<BasicBlock*>(this)->getSinglePredecessor();
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}
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//===--------------------------------------------------------------------===//
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/// Instruction iterator methods
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///
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inline iterator begin() { return InstList.begin(); }
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inline const_iterator begin() const { return InstList.begin(); }
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inline iterator end () { return InstList.end(); }
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inline const_iterator end () const { return InstList.end(); }
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inline size_t size() const { return InstList.size(); }
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inline bool empty() const { return InstList.empty(); }
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inline const Instruction &front() const { return InstList.front(); }
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inline Instruction &front() { return InstList.front(); }
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inline const Instruction &back() const { return InstList.back(); }
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inline Instruction &back() { return InstList.back(); }
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/// getInstList() - Return the underlying instruction list container. You
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/// need to access it directly if you want to modify it currently.
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///
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const InstListType &getInstList() const { return InstList; }
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InstListType &getInstList() { return InstList; }
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virtual void print(std::ostream &OS) const { print(OS, 0); }
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void print(std::ostream *OS) const { if (OS) print(*OS); }
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void print(std::ostream &OS, AssemblyAnnotationWriter *AAW) const;
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/// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const BasicBlock *) { return true; }
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static inline bool classof(const Value *V) {
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return V->getValueID() == Value::BasicBlockVal;
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}
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/// dropAllReferences() - This function causes all the subinstructions to "let
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/// go" of all references that they are maintaining. This allows one to
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/// 'delete' a whole class at a time, even though there may be circular
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/// references... first all references are dropped, and all use counts go to
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/// zero. Then everything is delete'd for real. Note that no operations are
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/// valid on an object that has "dropped all references", except operator
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/// delete.
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///
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void dropAllReferences();
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/// removePredecessor - This method is used to notify a BasicBlock that the
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/// specified Predecessor of the block is no longer able to reach it. This is
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/// actually not used to update the Predecessor list, but is actually used to
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/// update the PHI nodes that reside in the block. Note that this should be
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/// called while the predecessor still refers to this block.
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///
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void removePredecessor(BasicBlock *Pred, bool DontDeleteUselessPHIs = false);
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/// splitBasicBlock - This splits a basic block into two at the specified
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/// instruction. Note that all instructions BEFORE the specified iterator
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/// stay as part of the original basic block, an unconditional branch is added
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/// to the original BB, and the rest of the instructions in the BB are moved
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/// to the new BB, including the old terminator. The newly formed BasicBlock
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/// is returned. This function invalidates the specified iterator.
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///
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/// Note that this only works on well formed basic blocks (must have a
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/// terminator), and 'I' must not be the end of instruction list (which would
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/// cause a degenerate basic block to be formed, having a terminator inside of
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/// the basic block).
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///
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BasicBlock *splitBasicBlock(iterator I, const std::string &BBName = "");
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static unsigned getInstListOffset() {
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BasicBlock *Obj = 0;
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return unsigned(reinterpret_cast<uintptr_t>(&Obj->InstList));
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}
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private:
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// getNext/Prev - Return the next or previous basic block in the list. Access
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// these with Function::iterator.
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BasicBlock *getNext() { return Next; }
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const BasicBlock *getNext() const { return Next; }
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BasicBlock *getPrev() { return Prev; }
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const BasicBlock *getPrev() const { return Prev; }
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};
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inline int
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ilist_traits<Instruction>::getListOffset() {
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return BasicBlock::getInstListOffset();
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}
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} // End llvm namespace
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#endif
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