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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/InstrTypes.h"
#include <list>
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:
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);
//===--------------------------------------------------------------------===//
// Predecessor iterator code
//===--------------------------------------------------------------------===//
//
// This is used to figure out what basic blocks we could be coming from.
//
// Forward declare iterator class template...
template <class _Ptr, class _USE_iterator> class PredIterator;
typedef PredIterator<BasicBlock*, use_iterator> pred_iterator;
typedef PredIterator<const BasicBlock*,
use_const_iterator> pred_const_iterator;
inline pred_iterator pred_begin() ;
inline pred_const_iterator pred_begin() const;
inline pred_iterator pred_end() ;
inline pred_const_iterator pred_end() const;
//===--------------------------------------------------------------------===//
// Successor iterator code
//===--------------------------------------------------------------------===//
//
// This is used to figure out what basic blocks we could be going to...
//
// Forward declare iterator class template...
template <class _Term, class _BB> class SuccIterator;
typedef SuccIterator<TerminatorInst*, BasicBlock*> succ_iterator;
typedef SuccIterator<const TerminatorInst*,
const BasicBlock*> succ_const_iterator;
inline succ_iterator succ_begin() ;
inline succ_const_iterator succ_begin() const;
inline succ_iterator succ_end() ;
inline succ_const_iterator succ_end() const;
//===--------------------------------------------------------------------===//
// END of interesting code...
//===--------------------------------------------------------------------===//
//
// Thank god C++ compilers are good at stomping out tons of templated code...
//
template <class _Ptr, class _USE_iterator> // Predecessor Iterator
class PredIterator {
const _Ptr ThisBB;
_USE_iterator It;
public:
typedef PredIterator<_Ptr,_USE_iterator> _Self;
typedef bidirectional_iterator_tag iterator_category;
typedef _Ptr pointer;
inline PredIterator(_Ptr BB) : ThisBB(BB), It(BB->use_begin()) {}
inline PredIterator(_Ptr BB, bool) : ThisBB(BB), It(BB->use_end()) {}
inline bool operator==(const _Self& x) const { return It == x.It; }
inline bool operator!=(const _Self& x) const { return !operator==(x); }
inline pointer operator*() const {
assert ((*It)->getValueType() == Value::InstructionVal);
return ((Instruction *)(*It))->getParent();
}
inline pointer *operator->() const { return &(operator*()); }
inline _Self& operator++() { // Preincrement
do { // Loop to ignore constant pool references
++It;
} while (It != ThisBB->use_end() &&
((*It)->getValueType() != Value::ConstantVal));
// DOES THIS WORK???
//((*It)->getValueType() != Value::BasicBlockVal));
return *this;
}
inline _Self operator++(int) { // Postincrement
_Self tmp = *this; ++*this; return tmp;
}
inline _Self& operator--() { --It; return *this; } // Predecrement
inline _Self operator--(int) { // Postdecrement
_Self tmp = *this; --*this; return tmp;
}
};
template <class _Term, class _BB> // Successor Iterator
class SuccIterator {
const _Term Term;
unsigned idx;
public:
typedef SuccIterator<_Term, _BB> _Self;
typedef forward_iterator_tag iterator_category;
typedef _BB pointer;
inline SuccIterator(_Term T) : Term(T), idx(0) {} // begin iterator
inline SuccIterator(_Term T, bool)
: Term(T), idx(Term->getNumSuccessors()) {} // end iterator
inline bool operator==(const _Self& x) const { return idx == x.idx; }
inline bool operator!=(const _Self& x) const { return !operator==(x); }
inline pointer operator*() const { return Term->getSuccessor(idx); }
inline pointer *operator->() const { return &(operator*()); }
inline _Self& operator++() { ++idx; return *this; } // Preincrement
inline _Self operator++(int) { // Postincrement
_Self tmp = *this; ++*this; return tmp;
}
inline _Self& operator--() { --idx; return *this; } // Predecrement
inline _Self operator--(int) { // Postdecrement
_Self tmp = *this; --*this; return tmp;
}
};
};
//===--------------------------------------------------------------------===//
// Implement some stuff prototyped above...
//===--------------------------------------------------------------------===//
inline BasicBlock::pred_iterator BasicBlock::pred_begin() {
return pred_iterator(this);
}
inline BasicBlock::pred_const_iterator BasicBlock::pred_begin() const {
return pred_const_iterator(this);
}
inline BasicBlock::pred_iterator BasicBlock::pred_end() {
return pred_iterator(this,true);
}
inline BasicBlock::pred_const_iterator BasicBlock::pred_end() const {
return pred_const_iterator(this,true);
}
inline BasicBlock::succ_iterator BasicBlock::succ_begin() {
return succ_iterator(getTerminator());
}
inline BasicBlock::succ_const_iterator BasicBlock::succ_begin() const {
return succ_const_iterator(getTerminator());
}
inline BasicBlock::succ_iterator BasicBlock::succ_end() {
return succ_iterator(getTerminator(),true);
}
inline BasicBlock::succ_const_iterator BasicBlock::succ_end() const {
return succ_const_iterator(getTerminator(),true);
}
#endif