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//===-- llvm/BasicBlock.h - Represent a basic block in the VM ----*- C++ -*--=//
//
// This file contains the declaration of the BasicBlock class, which represents
// a single basic block in the VM.
//
// Note that basic blocks themselves are Def's, because they are referenced
// by instructions like branches and can go in switch tables and stuff...
//
// This may see wierd at first, but it's really pretty cool. :)
//
//===----------------------------------------------------------------------===//
//
// Note that well formed basic blocks are formed of a list of instructions
// followed by a single TerminatorInst instruction. TerminatorInst's may not
// occur in the middle of basic blocks, and must terminate the blocks.
//
// This code allows malformed basic blocks to occur, because it may be useful
// in the intermediate stage of analysis or modification of a program.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_BASICBLOCK_H
#define LLVM_BASICBLOCK_H
#include "llvm/Value.h" // Get the definition of Value
#include "llvm/ValueHolder.h"
#include "llvm/CFGdecls.h"
class Instruction;
class Method;
class BasicBlock;
class TerminatorInst;
typedef UseTy<BasicBlock> BasicBlockUse;
class BasicBlock : public Value { // Basic blocks are data objects also
public:
typedef ValueHolder<Instruction, BasicBlock> InstListType;
private :
InstListType InstList;
friend class ValueHolder<BasicBlock,Method>;
void setParent(Method *parent);
public:
typedef cfg::succ_iterator succ_iterator; // Include CFG.h to use these
typedef cfg::pred_iterator pred_iterator;
typedef cfg::succ_const_iterator succ_const_iterator;
typedef cfg::pred_const_iterator pred_const_iterator;
BasicBlock(const string &Name = "", Method *Parent = 0);
~BasicBlock();
// Specialize setName to take care of symbol table majik
virtual void setName(const string &name);
const Method *getParent() const { return (const Method*)InstList.getParent();}
Method *getParent() { return (Method*)InstList.getParent(); }
const InstListType &getInstList() const { return InstList; }
InstListType &getInstList() { return InstList; }
// getTerminator() - If this is a well formed basic block, then this returns
// a pointer to the terminator instruction. If it is not, then you get a null
// pointer back.
//
TerminatorInst *getTerminator();
const TerminatorInst *const getTerminator() const;
// hasConstantPoolReferences() - This predicate is true if there is a
// reference to this basic block in the constant pool for this method. For
// example, if a block is reached through a switch table, that table resides
// in the constant pool, and the basic block is reference from it.
//
bool hasConstantPoolReferences() const;
// dropAllReferences() - This function causes all the subinstructions to "let
// go" of all references that they 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();
// splitBasicBlock - This splits a basic block into two 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 new 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).
//
BasicBlock *splitBasicBlock(InstListType::iterator I);
};
#endif
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